Sirte University Scientific Journal (SUSJ)
)Periodical Academic Refereed( Applied Sciences
Volume 10, Issue No. 1, June 2020
General Director Prof. Ahmed F. Mahgoub
Editor in Chief Dr. Abdalsalam M. Muftah
Editorial Board
Dr. Hamid M. Younis Dr. Soliman M. Alshater Dr. Algaddafi S. Alpotte Dr. Khalifa M. Fadil Abdalmawla A.Ali Dr. Abobaker Eljilani Abobaker
Sirte University Scientific Journal
Post Box 674 Sirte, Libya
Tel: 00218545265704-1178
Fax:00218545262152-1178 Email: [email protected]
Sirte University Scientific Journal (SUSJ)
A scientific refereed journal issued on behalf of Sirte University in a number of issues throughout the year interested in publishing research and documented studies in the field of humanities and applied sciences for university faculty members and other universities from inside and outside Libya .
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Sirte University Scientific Journal (SUSJ)
Paper Submission
. Sirte University Scientific Journal (SUSJ) is referred journal issued by the Sirte University in the fields of humanities and applied sciences in English.
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III
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Authors should send their papers to:
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IV
Sirte University Scientific Journal
General Director's Word
In the name of Allah The Most Gracious The Most Merciful
All praise be to Allah and peace and Blessings be upon the Prophet Muhammed
Sirte University Scientific Journal is an official refereed journal. It published peer- reviewed research in the fields of humanities and applied sciences.
As one of its mission has been to improve the scientific research in order to broaden the people’s knowledge and serve the local community, and since the scientific research has been widely recognized as of one of the main standards As the University’s President and the on which universities’ performances and General Director of the journal, I am so contributions are assessed in all over the delighted to present you with the current world, we had to do our upmost to ensure edition of the journal. It is also my great the publication of the 1ed issuance of 10 th pleasure to extend my gratitude to the volume- June. 2020) which includes University’s faculty members, graduate thehumanit y and sciences volumes. students, researchers and reviewers who have all contributed in the publication of this issue It is worth mentioning that the and hoping that the editorial board has SUSJ, in a very short time and with very selected the most valuable research papers to limited resources, has made significant be published in this edition. I should mention and tangible achievements, namely, the here that we, very much, welcome any spearheading of research culture, comments and/or suggestions which could exchanging of expertise, boosting the help in improving the next editions. spirit of cooperation and encouraging researcher to publish their valuable Finally, I commend all the hard work and research papers in different scientific efforts exerted by the Editorial Board and to fields. all people who have contributed, directly or indirectly, in bringing this issue into life.
Peace be upon you
The General Director
V
Sirte University Scientific Journal Editor in Chief's Word
In the name of Allah The Most Gracious The Most Merciful
It remains my great honour to serve as Editor-in-Chief of the Sirte University Scientific Journal (SUSJ), and it is my pleasure to take this opportunity to thank everyone involved in the continuing success of the journal, and we would never have made it this far without the enthusiasm and assistance of the journal’s Editorial Board, and its readers. There are two special groups who are also included in the above, our referees and our authors. Without the referees’ valuable comments, the quality of the papers would not be as Although every effort has been made to high as it is. Without the authors’ choice of make this journal errors-free and as SUSJ in which to publish their best work, scientific as possible, no work is perfect the journal’s contribution to our and this journal is not an exception. community simply would not be as great as Therefore, we appreciate it if you could it is. It is also thanks to the hard work of give us your feedback, suggestions and both our authors and our referees that our ideas in order to improve the next issues. publications enable all our readers to keep up with the latest developments within our sphere of research as early as possible.
We look forward to your most serious and effective efforts, which aspire May Pease be Upon You members of the editorial board and its general director, also aspire to the Editor in Chief university in the dissemination of scientific research in all fields of human and applied sciences.
VI
Sirte University Scientific Journal (Applied Sciences) Vol.10 (1), June 2020
Contents Using Reuse of Debris of Damaged Buildings by Armed Conflicts in Libya and Mill Scale Scrap to Produce Sustainable Concrete F.Alatshan A. Altlomate and M. Ahmed 1-17
Influence of Grain Refinement by Al-5Ti-1B on the Microstructure and Mechanical Properties of Aluminium Alloy A356 18-29 A. A. Khalil, M. H. Alkathafi and R. M. Esmaael
Theoretical Study of Producing Sustainable Electrical Energy via Hydraulic Energy 30-42 K. Khalifa, M. Bughazem, I. Saleh, and M. Alghool
Performance Evaluation of Feed Forward Neural and Recurrent Neural On Real System Dataset of Robot Execution 43-51 A.k. Diryag, N. A. Ali, k. M. Legweel
Quality Assay Measurements of Groundwater in Wadijarif– Sirte-Libya 52-63 Aesha F. R. Amhamed
The Role of Ultrasound in The Diagnoses of Graves’ Disease F.M.Shembesh , M. E. Buzgheia, F. M. Kutrani , N.F.BenJeweref, N. M. Elbagermi, 64-73 S. A. Salem
Unilateral Dermoid Ovarian Cyst In Nulliparous Women Mona Mohammed Al gobbi 74-80
Removal of Multi Heavy Metals in One Batch System onto Surface of Activated Palm Kernel Ragwan Mohamed and Alaa Mustafa 81-86
VII
Using Reuse of Debris of Damaged Buildings …...
Sirte University Scientific Journal (Applied Sciences) Vol.10 (1), June 2020
Using Reuse of Debris of Damaged Buildings by Armed Conflicts in Libya and Mill Scale Scrap to Produce Sustainable Concrete
Faesal Alatshan1 Abdelmajeed Altlomate2 and Muhammad Farooq Ahmed3 [email protected]
1Department of Civil Engineering, College of Engineering Technology, Houn, Libya, 2Department of Civil Engineering, Faculty of Engineering, Sirte University, Libya 3Department of Geological Engineering, University of Engineering and Technology, Pakistan
Abstract
In Libya, recycling of waste materials is not a common practice. The enormous amount of waste resulting from the destruction of the buildings due to the armed conflict, could be witnessed in most parts of the country. This paper aims to present more sustainable and environmental friendly concrete mix design by utilizing some of the locally available debris waste and mill scale scrape.
The previous studies carried out in this area favors the possibility of the effective utilization of locally available building debris in concrete mix design. In this research work, two types of sustainable materials (recycled concrete aggregates and steel mill scale) were incorporated to the concrete mix design. Firstly, the recycled concrete aggregates were used as a substitute of natural aggregates in certain proportions (i.e. 10, 30 and 60%). Secondly, steel mill scale was added to the concrete mixture as an alternative to replace a fraction of cement with the following different percentages i.e. 2, 6 and 10%.
The behavior of hardened concrete produced using these sustainable alternatives was investigated by performing the compressive strength, flexural strength of concrete and Ultrasonic Pulse Velocity (UPV) tests. The resultant mechanical properties of the concrete (produced from incorporating debris waste) found satisfactory which further emphasize on the possibility of reusing debris waste in concrete mix design for construction purposes.
Keywords: Recycling, Sustainable, Environmental, Concrete, Aggregates, Mill Scale.
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1. Introduction
It is well known that concrete is the second most consumed material after water [1]. Concrete is the essential part of the building materials for different type of structures, ranges from schools, houses, factories, high-rise buildings, dams, airfields and many others. Keeping in mind the significant role of the concrete, it is utmost important to focus on its reuse and the new trends and possible way outs to come up with economical concrete mix designs with having better engineering performance. The particular concrete mix design should not only meet the anticipated performance but also comply with environmental, social and economic requirements. The application of the concept of sustainability and green building engineering design could help to achieve these objectives [2]. Sustainability and green buildings concept is based on the key factors including; maintaining environment by reducing the consumption of natural resources by reusing the wasted construction material. This could further provide employment opportunities for local labor, and the provision of utilizing building materials near to the project site and reduce the construction material transportation cost. The application of sustainable engineering, socially contributes to improve the economic standards of the local community and through educating and training them on the effective use of these materials. Sustain means to keep a process going, and the objective of sustainability is that life on the planet can be sustained forever. There are three important components of sustainability: environment, society, and economy. To meet its aim, sustainable progress must provide that these three components stay balanced. At this time, the environment is the most important component and required significant attention to compensate the deterioration of our atmosphere worldwide by focusing on sustainable development approaches.[3] Recently there is an enormous amount of increase in the concrete debris waste resulted from the demolition and reconstruction of buildings all over the world since the last decade of the twentieth century. The disposal of this kind of waste through dumping and accumulating in private landfills, could cause negative environmental impacts[4]. These construction wastes contain recyclable material like rebar, aggregate and concrete lumps with economic value. The utilization of such material in construction industry could play an axiomatic role in the progress of developing countries like Libya. Despite the fact that these wastes might not lead to produce the concrete with desired strength, however, environmental factor remains the biggest motivation for the consideration of this practice in the construction of buildings with adequate strength. According to the World Business Council for Sustainable Development (WBCSD: 2012) [5], the cement industry is responsible for 5% of carbon dioxide emissions. This fact indicates that the reduced production of cement would directly reflect on the emissions of carbon dioxide and other environmentally hazardous gases by incorporating varying degree of the amount alternative materials such as dust of silica, fly ash, slag, rice ash, glass crunched and many other materials [6]. In Libya, the concrete consumption is around 97% in the construing most of the structures ranging from houses to multistory buildings [7]. Moreover, many of the existing buildings in the country require rehabilitation, renovation or reconstruction. The demand of natural aggregates for these projects could pose additional negative environmental impact by demanding the new search of quarrying the alternative sources of aggregates to reduce in the country which is already facing the acute shortage of natural aggregate sources. 2 Vol.10 (1),01-17, June.2020
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The negative environmental effect, resulted from the excessive use of natural aggregates could be observed in certain parts of Libya from the satellite images captured in different times in the recent past (see Figures 1-4). These images show the visual comparison of lands use changes in the vicinity of natural aggregate quarry locations before and after excavation of the natural aggregates. These images revealed a significant change in the area as the mining industry have consumed large zones of land that was a part of agricultural, residential, tourist activities.
Figure 1. Site for bricks quarry near the city Figure 2. Site for bricks quarry near the city of Surman, image before the excavation. of Surman, image after the excavation.
Figure 3. Another site of bricks quarry near Figure 4. Another site of bricks quarry near the city of Surman, image before the the city of Surman, image after the excavation. excavation.
Large amounts of mill scale result from the steel rolling factories, these amounts of wastes were estimated as 11000 tons annually, according to the statistics of the Libyan Iron and Steel Company (LISCO). [9]. These amounts of waste could be effectively utilized in the concrete to achieve the desired strength.
In 2011, the total debris waste produced as a result of the significant destruction in the recent armed conflicts in Libya, was estimated as more than 80 million tons, that exceeds the amount of construction waste produced by 15 European countries combined in that year (see Figure 5) [8]. Previous study conducted by Elazhari et al in 2013 has shown that there were few possibilities to rehabilitate and renovate few of the buildings. Moreover, the other studies outcomes also favors to 3 Vol.10 (1),01-17, June.2020
F.Alatshan A. Altlomate and M. Ahmed reuse of this type of enormous construction waste [8].
82 ليبياLibya
72 15دولة European 15اوروبية countries
54 متحدةUSA
34 اليابانJapan
0 20 40 60 80 100
Figure 5. Construction waste produced for the year 2011 in million tons in different parts of the world in comparison with Libya [8]
The present study is carried out to emphasize on the proper use of recycled aggregates produced from demolished buildings waste and the residual material generated by the steel factories, in the concrete mix design. In this study the compressive and flexural strength tests were performed on reformulated concrete of 60 days old. Ultrasonic Pulse Velocity (UPV) test were also conducted on the concrete samples to determine it mechanical properties.
2. Material and Methodology
To conduct the strength test on the reformulated concrete, the following materials were utilized in different proportions
. Cement: Ordinary Portland cement (N. 42.5) product locally in accordance with the Libyan specifications No. 340/2009 [9]. . Water: Tap water was used in making and curing the specimens as per Libyan specifications No. 8911 :492 [10]. . Steel Mill Scale Scrap: It is a powder of flaky steel particles of metallic-gray color with a spangle (see Figure 6). Mill Scale is considered as a by-product formed during the steel- making process and in particular during the hot rolling stage. Mill Scale material was brought from LISCO for this study; the Chemical properties and Particle-size analysis test results are illustrated in Table 1 and 2 respectively.
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Table 1. Chemical Properties of Mill Table 2. Particle-Size of Mill Scale Scale Scrap. Scrap.
Components %Average Grade Particle-Size (mm) Passing (%)
Fe 67.00 0 to 12 mm 90
SiO2 3.37 More than 12 mm 10
AlO3 1.10
CaO 2.45
P 0.08
S 0.05
MnO 0.57
H O Maximum 5 2 Oil 0.9 Figure 6. Mill Scale Scrap.
Figure 7. Collection of the Steel Mills Scale at Libyan Iron and Steel Company
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Figure 8. Transportation of the Steel Mills Scale at Libyan Iron and Steel Company
. Fine Aggregates: Natural aggregate available in Wedan in Al-Jufra area was selected for this research work. Table 3 presents the physical properties of fine aggregate and Table 4 shows the particle size distribution of the sand. Table 3. Physical Properties of Fine Table 4. Particle-Size of Fine Aggregates. Aggregates
Property Results Particle-Size (mm) Passing (%) Moisture content (%) 0.17 4.2 811
Compaction factor (%) 2.83 8.42 99.2
Specific weight 2.65 1..0 12..
Liquidity limit (%) 16.34 1.08 22
1.8. 82..
. Coarse Aggregates: Two types of coarse aggregates, including both natural and recycled concrete aggregates were used in this study. The natural aggregates produced from basaltic rocks available in Sokana at Al-Jufra area Libya and; the recycled concrete aggregates were obtained from breaking down the concrete waste of three different destructed military compounds
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(demolished as a result of aerial bombardment in military conflicts in 2011 in the Al-Jufra region (See Figures 9-11).
Figure 9. (Location 1) Main building of Defense Ministry Main building in Houn, Al-Jufra, Libya.
Figure 10. (Location 2) Ammunition Store in Sokna, Al-Jufra, Libya.
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Figure 11. (Location 3) Al-Jufra Air Base, Houn, Al-Jufra, Libya.
The breaking down of these blocks was first done manually at the site, and later the electrical crusher was used to crush the recycled concrete aggregate up to the desired size. The resulted aggregate was washed with clean water to remove any suspended material or dust particles. Finally, the aggregates were dried in an electronic oven at the temperature range of 100-110 Co. The particles size distribution results of both natural and recycled aggregates are given in Table 5.
Table 5. Particle-Size of Coarse Aggregates
Particle-Size Standard limits Passing (%) (mm) )%(
)BS 882: 1992(
21 811 811 41 12 811 - 91 81 02 .1 - 01 2 1 81 - 1
A series of tests were carried out on the various types of natural and recycled aggregate samples; including specific weight, water absorption, crushing value and impact value. Figures 12-15 show a comparison between the physical properties of different types of aggregate combinations in this study. The figures also show the appropriate limits to be used in concrete mix design. 8 Vol.10 (1),01-17, June.2020
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Natural Agg. Location 1 Location 2 Location 3
Figure 12.Comparison Between the Specific Gravity of Aggregate Combinations Utilized for this Study.
Specification limits
Natural Agg. Location 1 Location 2 Location 3
Figure 13. Comparison Between Water Absorption of Various Aggregate Combinations Utilized for this Study.
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Natural Agg. Location 1 Location 2 Location 3
Figure 14. Comparison Between Impact Value of various Aggregate Combinations Utilized for this Study.
Specification limits
Natural Agg. Location 1 Location 2 Location 3
Figure 15.Comparison Between Crushing Value of Various Aggregate Combinations Utilized for this Study.
According to the test results, it was noted that the specific weight of recycled aggregates was in compliance to the requirement of British Standards[11] except the natural aggregates, used in the Al-Jufra region that have a specific weight exceeding the limits of the standards. The rate of water absorption test reveals that the natural aggregates showed satisfactory results, while the recycled aggregates were found little high in absorption, this could probably be due to the amount of cement mortar layer within the aggregates. The impact and crushing values of aggregate results show the best coefficients for natural aggregates and recycled aggregate results were also found in compliance with the limits of standards [12, 13].
A microscopic examination of both natural aggregates and the recycled aggregates from Location 1 is shown in Table 6.
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Table 6. The Microscopic Inspection of aggregates.
Lens Type Natural Aggregates Recycled Concrete Aggregates Comments
In both cases, aggregate sizes are Normal Lens irregular in shape that require more .water and cement
The outer surface of the recycled LU Plan Flour aggregates contain fine particles cover X/0.30 A11 on it in addition to the natural .aggregates
More number of pores in the surface LU Plan Flour of recycled X/0.45 A21 aggregates as compared to the . natural aggregates
Concrete Mix Design
Total 10 concrete mixt designs were utilized to study its behavior by varying the constituted material proportions (Table 7). As shown in the Table 7, the recycled concrete aggregates (RCA) (brought from location 1), were utilized as a partial substitution of natural aggregate (NA) with ratios
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F.Alatshan A. Altlomate and M. Ahmed of 10%, 30% and 60%. Additionally, Mill scale was used with the ratio of 2% 6% 10% as an alternative of cement weight.
Table 7. Mix Design Proportion for 1 m3 of Concrete.
Components (Kg/m3) Concrete mix Mill Scale)%( W/C)%( RCA)%( NA RA Sand cement
N-MS0 1 1.. 1 8411 1 .21 021 N-MS2 4 1.. 1 8411 1 .21 020 N-MS6 . 1.. 1 8411 1 .21 049 N-MS10 81 1.. 1 8411 1 .21 082 R10-MS0 1 1.. 81 8824 841 .21 021 R10-MS6 . 1.. 81 8824 841 .21 049 R30-MS0 1 1.. 01 19. 012 .21 021 R30-MS6 . 1.. 01 19. 012 .21 049 R60-MS0 1 1.. .1 284 8.1 .21 021 R60-MS6 . 1.. .1 284 8.1 .21 049
Strength Test Results and Discussions:
Furthermore, the compressive strength and flexural strength of concrete and Ultrasonic Pulse Velocity (UPV) tests were conducted to investigate the mechanical properties of the concrete.
Compressive Strength
The compressive strength tests on hardened concrete were conducted according to British Standards (BS 1881 part116: 1983) [14]. Figure 16 shows the results of compressive strength of concrete cube at the age of 60 days. The results revealed that the addition of the recycled concrete aggregates in different proportions do not reduce the compressive strength of the concrete significantly. For the specimens containing 10%, 30% and 60% of the recycled concrete aggregates, the compressive strengths were determined as 49.42 N/mm2, 50 N/mm2, and 46.19 N/mm2 respectively, which is in accordance with the reference concrete value (i.e. 50.6 N/mm2).
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The effect of adding the steel mill scale in different proportions without recycled concrete aggregates was also investigated. The results show that the addition of 2% mill scale leads to decrease the compressive strength of concrete as compared to the reference samples. However, an increase in the compressive strength of concrete samples was noticed by using 6% and10% of mill scale in the concrete mix design. For instance the compressive strength of the concrete samples with 10% mill scale was obtained 49.32 N/mm2 which is approximately equal to the reference concrete sample value (i. e. 50.6 N/mm2).
60 50.6 49.16 49.32 49.42 50 47.84 48.48 50 46.66 46.19
40 32.18 30
20
10
0
N-MS0 N-MS2 N-MS6 N-MS10 R10-MS0 R10-MS6 R30-MS0 R30-MS6 R60-MS0 R60-MS6 Compressive Compressive strength (MPa) Concrete mixtures Figure 16.The Results of Compressive Strength of Concrete at the Age of 60 Days.
Flexural Strength
The flexural strength Tests on hardened concrete were conducted according to ASTM Standards (ASTM:C78) [15]. The results presented in Figure 17 show an increase in flexural strength of the concrete with using 6% mill scale and 30% of recycled aggregates as compared to the reference concrete. This could happened because of the effect of mill scale addition that worked as a mineral fiber to resist tensile stress, that further helped in improving the strength of reinforced concrete. A decrease in the flexural strength of concrete was noticed for the concrete mix design having 30% of recycled concrete aggregates without mill scale.
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4.4
4.3 4.275
4.2 4.14
4.1
4 3.915
3.9 Flexural strength(MPa)
3.8
3.7 N-MS0 R30-MS0 R30-MS6 Concrete mixture
Figure 17.The Results of Flexure Strength Tests.
UPV Test
UPV Test on concrete was conducted according to (ASTM: C597) [15]which is considered as one of the reliable non-destructive concrete tests. This test show the change in the mechanical properties of samples over the time[16].
Overall, the UPV results presented in Figures 18-20, show that the speed of UPV increases with the increase in the age of the concrete which in turn indicates the improvement in mechanical properties until the age of 60 days for all samples. The Figures also reveals that such concrete mixtures containing mill scale in their composition have a higher UPV speed than the mixtures containing recycled concrete aggregates. The reason could likely be the presence of conductive compounds (iron), which may have a role in the increase in velocity of UPV. In contrast the recycled aggregate likely makes the concrete more porous that could reduce the speed of the ultrasound waves[16].
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5
4.8
4.6
4.4
4.2 N-MS0 N-MS2 4 N-MS6
UPV UPV (mm/s) Speed N-MS10 3.8 3 14 21 28 60 Age of concrete (days) Figure 18.UPV Speed of Concrete Samples Containing Mill Scale only
4.8
4.6
4.4
4.2 N-MS0
UPV UPV (mm/s) Speed R10-MS0 R30-MS0 4 R60-MS0
3.8 3 14 21 28 60 Age of concrete (days) Figure 19. UPV Speed of Concrete Samples Containing Recycled Concrete Aggregates only
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4.9 4.8 4.7 4.6 4.5
4.4 Speed (mm/s) 4.3 N-MS0 4.2 4.1 3 14 21 28 60 Age of concrete (day) Figure 20. UPV Speed of Concrete Samples Containing both Recycled Concrete Aggregates and Mill Scale.
3. Conclusions
This study emphasis to prepare a reasonable concrete mix design with better mechanical properties with the addition of available debris waste. In this study the behavior of hardened concrete produced by using the sustainable alternatives was investigated in the country Libya by performing the compressive strength, flexural strength of concrete and Ultrasonic Pulse Velocity (UPV) tests. The resultant mechanical properties of the reformulated concrete are concluded below. 1. The substitution of 30% of the total weight of natural aggregates with recycled aggregates in the concrete mix gave the best results for the compressive strength of concrete. 2. The replacement of the cement in concrete containing recycled aggregates and mill scale in different percentages do not reduce its compressive strength tests significantly and still gave values close to the reference value concrete. 3. The inclusion of mill scale as a substituent of cement, combined with natural aggregates gives better compressive strength as compare to the concrete having recycled aggregates component only. 4. The addition of the mill scale also improved the flexural strength of the concrete. Indeed, the addition of 6% of mill scale as a substitute for cement, and 30% recycled aggregates as substituent of natural aggregates gave the reasonable values of the flexural strength for the concrete samples. Overall the resultant mechanical properties of the concrete, obtained from incorporating debris waste and mill scale found satisfactory that emphasized on the possibility of reusing debris waste in concrete mix design for construction purposes in Libya. Such recommendations could certainly reduce the environmental issues associated with the new construction and related industry in the deadly war hit areas. 16 Vol.10 (1),01-17, June.2020
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References
1. Klee, H., The Cement Sustainability Initiative: Recycling Concrete. 2009, World Business Council for Sustainable Development – WBCSD: Washington, D.C. United States. 2. Alatshan, F., R. Shaladi, and F. Mashiri, Sustainableconcrete: Overview ofrecent developments andapplications in 12th ARAB STRUCTURAL ENGINEERING CONFERENCE. 2013: Tripoli. 3. Struble, L. and J. Godfrey. How sustainable is concrete. in International Workshop on Sustainable Development and Concrete Technology. 2004. 4. F. Alatshan, A.A., B. Lamouchi Utilisation de déchets locaux pour la production d’un béton écologique. in JSFM-CMC 2015. 2015. Annaba University. 5. WBCSD, The Cement Sustainability Initiative: Progress report. 2012, World Business Council for Sustainable Development: Washington, DC. 6. Alatshan, F., R. Shaladi, and F. Mashiri, Sustainableconcrete: Overview ofrecent developments andapplications. 7. Ngab, A.S., Libya—The construction industry—An overview. Karachi: Ned University of Engineering and Technology Karatchi Pakistan, 2007. 8. A, E.S., E.B. Zara, and H. Ghrooda, Recycle material of the damaged buildings, in Recycle material of the damaged buildings. 2013: Tripoli 9. LSS:340, LIBYAN STANDARD SPECIFICATIONS, in Portland cement. 2009, Libyan National Center for Standardization and Metrology. 10. LSS:294, LIBYAN STANDARD SPECIFICATIONS, in Water used in concrete. 1988, Libyan National Center for Standardization and Metrology. 11. Part2, B., Testing aggregates. Methods for Determination of Density, B.S. Institution, Editor. 1995: London, UK. 12. 812-112, B., Testing aggregates. Method for determination of aggregate impact value (AIV), B.S. Institution, Editor. 1990: London, UK. 13. 812-110, B., Testing aggregates. Methods for determination of aggregate crushing value (ACV), B.S. Institution, Editor. 1990: London, UK. 14. 1881-116, B., Testing concrete. Method for determination of compressive strength of concrete cubes, B.S. Institution, Editor. 1983: London, UK. 15. ASTM:C78/C78M, Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading). 2015, ASTM International West Conshohocken, PA. 16. Popovics, S., J.L. Rose, and J.S. Popovics, The behaviour of ultrasonic pulses in concrete. Cement and Concrete Research, 1990. 20(2): p. 259-270.
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Sirte University Scientific Journal (Applied Sciences) Vol.10 (1), June 2020
Influence of Grain Refinement by Al-5Ti-1B on the Microstructure and Mechanical Properties of Aluminium Alloy A356
Abdalfattah A. Khalil1, Maftah H. Alkathafi2 and Rafaa M. Esmaael3 [email protected]
2Mechanical Engineering Department, Faculty of Engineering, Sirte University, Libya 1&3Materials Science Department, Faculty of Engineering, Omer Al-Mukhtar University, Libya
Abstract
An investigation was carried out to understand the effect of grain refinement on the microstructure and mechanical properties of Al-alloy A356 by addition of varying weight percentage of Al-5Ti-1B. Grain refinement and modification of α- phase in Al-Si alloys are considered as important task resulting from solidification process. Two different approaches to grain refinement by solidification process have been pursued physically induced and chemically stimulated. The physical relies mainly on the use of external field, such as ultrasonic vibration, while the chemical approach depends primarily on addition of grain refiner, which is the subject of this research work. The effect of grain refiner on the solidification of the A356 alloy was studying and the obtained samples were characterized by optical microscopy. The mechanical properties (σuts, σ0.2 and δ) of the refined A356 alloys were investigated as a function of the addition level of Al-Ti-B master alloy (0, 1, 3,5 wt.%). The results indicated that the primary α- phase aluminium are significantly refined and the microstructures changed from coarse dendrites to fine equiaxed α-Al dendrites, without any change in the morphology of the eutectic Si particles. Additionally, the tensile strength, yield strength and elongation are increased noticeably with addition of grain refinement. The tensile strength, yield strength and elongation of the A356 with 3 wt % grain refine of (Al -5Ti- 1B) are 156.3 MPa, 104.3 MPa and 4.9%, i. e., the percentage of improvement was 12 %, 6 % and 8.9 %, respectively.
Keywords: Aluminium alloy-A356, Grain refinement, Modification of α- phase, Microstructure, Mechanical properties 1. Introduction
Aluminium alloys are known to have excellent strength to weight ratio compared with other conventional metals like steels. A356 is one of the most widely used aluminium alloys in many industrial applications because of its excellent castability, corrosion resistance and good mechanical properties. It has lower production cost, fast machining rate and good recyclability [1]. Grain 81 Vol.10 (1),18-29,June.2020
Influence of Grain Refinement by Al-5Ti-1B on …... refinement plays an important role to determine the quality and integrity of aluminium alloys. Grain refinement is considered to be an important melt treatment during the casting of aluminium alloys, and introduce of inoculating particles into melts is the most effective way to achieve small uniformly distributed equiaxed grains, which leads to high toughness, high yield strength, excellent formability and improved machinability. Al–Ti–B ternary master alloys, particularly Al–5Ti–1B, have been widely used as aluminium grain refiners over the past several decades. The Al–5Ti–1B master alloy offers a remarkable performance in the continuous and semi-continuous casting of wrought alloys, but fails to meet the expectations in the case of cast aluminium alloys, especially for the Al–Si [2,3]. The effects of addition of Al-5Ti-1B grain refiner on the microstructure, mechanical properties and the acoustic emission characteristics of Al-5052 aluminium alloy have been studies [4]. Microstructural analysis showed the presence of primary α- solid solution and the absence of Al- Mg phase. The results indicated that the addition of Al–5Ti–1B grain refiner into the Al-5052 alloy caused a significant improvement in mechanical properties. The main mechanisms behind this improvement were found to be due to the grain refining during the solidification and segregation of Ti at primary α- grain boundaries. In another previous study [5], commercial A356 alloy was refined with Al–5Ti–0.25C–2RE master alloy, and the microstructure and macrostructure of the refined alloy were investigated. The results show that the grain refining effect of A356 is poor by the addition level of 0.5 wt% master alloy, but when the level reaches 3.0 wt% the grain can get a satisfactory refining effect. Few researchers have made an attempt on various grain refiners with their mechanism, such as Al-10Sr on A356 alloy. The results indicated that a size decrease of α-Al dendrites, change in eutectic Si and enhancement in the mechanical properties. The change of grains from eutectic Si to rounded particles explained the mechanical properties improvement [6, 7]. The main objective of present research work is to study the effect of Al-5Ti-B on the microstructure and the influence of the structural refining on the mechanical properties of aluminium alloy-A356.
2. Experimental Work
2.1 Materials A commercial Aluminium – Silicon based alloy, A356, was used in this investigation with chemical composition as provided by the supplier “ASTM” shown in Table 1.
Table 1. Chemical composition (wt. %) of A356 “ASTM”. Si Fe Cu Mn Mg Zn Ti Other Al
Min 6.5 - - - 0.20 - - -
Max 7.5 0.6 0.25 0.35 0.45 0.35 0.25 0.15 Balance
This alloy was supplied from Aluminium Company of Egypt in the ingot form of A356-1, the delivered alloy of A356 was chemically analyzed (actual analysis) with the help of optical immersion process and the result is shown in Table 2.
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A. A. Khalil, M. H. Alkathafi and R. M. Esmaael
Table 2. Chemical composition (wt %) of the A356 Al-alloy used in this study. Si Fe Cu Mn Mg Zn Ti Other Al
7.36 0.15 0.0462 0.00129 0.329 0.00229 0.136 0.012 Balance
The Aluminium – Silicon phase diagram shows that the equilibrium eutectic constitution is about 12.6 wt% silicon. Figure 1 shows that the aluminum-silicon eutectic can form as follows: . Directly from the liquid in the case of a silicon concentration of 12.6%, for a eutectic aluminum-silicon alloy. . In the presence of primary aluminum in the case of silicon contents less than 12.6%, for hypoeutectic aluminum-silicon alloys), and . In the presence of primary silicon crystals in the case of silicon content greater than 12.6%, for hypereutectic aluminum-silicon alloys. The chosen aluminium alloy in this study consider as in a hypoeutectic Al-Si alloy. Its liquids temperatures started at 614°C and solidification ended at 577°C (eutectic temperature). The microstructure comprises both primary Fcc- aluminium solid solution containing 1.65wt% silicon and eutectic containing silicon enriched aluminium and pure silicon [8].
Figure 1. Al-Si phase diagram showing hypo-and hyper-eutectic alloys.
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2.2 Addition of Grain Refiner An amount of 1.5 Kg of A356 alloy was melted in a heat resistance furnace with using of a steel crucible coated from inside with graphite. After complete melting of the alloy, the temperature of the molten metal was kept at a temperature of 740 °C± 10 °C, which is higher than its liquidus temperature by about 125 °C to allow the complete dissolution of the silicon particles. Aluminium alloy Al–5Ti–1B was used in this investigation as grain refiner, then treated with addition different amounts of grain refiners, 0%, 1%, 3%, 5 wt. %, respectively. After addition of the grain refiner, the melt was manually stirred with a steel rod coated with a graphite and was maintained at 740 °C for 5 minutes for homogenization. The thermocouple type K (chromel–alumel) is accurate, inexpensive and has a wide temperature range, this type of thermocouple was used in measuring the temperature during melting process, and in addition, calibration was done before and after each series of melts.
2.3 The Microstructure Analysis
Metallographic samples were cut from the same position for all experiments, the distance was 15mm from the bottom of casting, as shown in Figure 2, and the samples were prepared according to used procedures development of aluminum alloys. The specimens were obtained under different condition with adding the (0, 1, 3, 5 wt. %) of Al-5Ti-1B master alloy. The specimens were taken from each cast sample for microstructure analysis by sectioning the cylinders parallel to its longitudinal axis, three specimens for microstructure analysis were made from one section. The samples were cut and grinding using standard metallographic procedures. The grinding was done by using 240, 320, 400, and 600 grit papers. Then, the samples were polished using 1 µm, and 0.05 µm Alumina suspension in water. A final polishing was done using silica suspension. The samples were thoroughly cleaned after each step.
15mm
Figure 2. Location of specimens from bottom of cast cylinder of Aluminum Alloy-A356.
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A. A. Khalil, M. H. Alkathafi and R. M. Esmaael
2.3.1 The Optical Microscopy and Quantitative Characterization
The samples that used for characterization optical microscopy were etched using 0.5% HF solution to reveal the resulting microstructure [9]. Grain size, length, and width of both eutectic silicon and α - aluminium are measured by linear intercept method applied to the microstructure obtained from polarized light in optical microscope at 400X. Six digital micrographs are processed using image C- software. The average of ten readings is taken from the results.
2.4 Tensile Test
The tensile tests of samples were carried out at ambient temperature of 25 °C using UH- F1000KNI/Shimadzu universal testing machine with a strain rate of 5 mm/min. The stress and strain curves were provided as a computer output by the control unit of the test machine. The samples were taken from each cast piece by sectioning the cylinders parallel to its longitudinal axis for tensile testing, three tensile test specimens were fabricated from one section, the location for tensile test is shown in Figure 3, the gauge length of the tensile test specimens was 36 mm and 6mm diameter as described in ASTM E8M [10].
Figure 3. Schematic drawing of tensile test specimen and their location in the mould with ASTM E8.
3. Results and Discussion
3.1. Microstructure of A356
Microstructures of the solidified samples taken from the mould without adding the Al-5Ti-1B master alloy are presented in Figure 4(a,b,c), the microstructure exhibits the overall matrix and eutectic Si
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Influence of Grain Refinement by Al-5Ti-1B on …... morphology respectively. The microstructure of the as-cast aluminium alloys A356 is a fully dendritic structure of α solid solution and eutectic silicon. Figure 4a showed also coarse acicular eutectic silicon dispersed among the fully developed dendritic primary α-aluminium (white) and eutectic silicon (dark- gray). One branch of a primary α-aluminium was about 600 μm in length, as shown in Fig. 4a, which indicated that the grain size was about a few millimeters as one grain usually contained several arms. The microstructure of the hypoeutectic aluminium alloys (A356), usually consists of coarse dendritic α-Al solid solution and Al–Si eutectic, where Si usually observed as long plate or big spheres shape. There were a number of researchers reported the presence of intermetallic phases like the eutectic Al2Cu “Chinese script” shaped α-Al15 (Mn,Fe)3Si2 and long sharp needles of β-Al5FeSi, which precipitate in the interdendritic and intergranular regions, and strongly detrimental to the alloy mechanical and fatigue properties [11, 12]. 3.2 The Microstructure of A356 with inoculated by Al-5Ti-1B A typical optical microscopy images of the A356 alloy with adding the (1, 3, 5 wt. %) Al-5Ti-1B master alloy are shown in figure 4(d,e,f). It is clearly that in the absence of grain refiner, the cast A356 alloy consists of dendritic primary α-Al and interdendritic needle plate-like eutectic silicon distributing randomly as shown in Figure 4(a). However, after adding the Al-5Ti-1B master alloy, the microstructures changed from coarse dendrites to fine equiaxed α-Al dendrites, without any change in the morphology of the eutectic Si particles. The grain refiner does not modify the eutectic Si as expected, this is shown in Figure 4(d,e,f). On the other hand, it can be seen that the primary α-Al phase that is not treated by grain refinement, was developed obviously into fully dendritic with the average length of its primary arm up to 1400μm as shown in Figure 4(c). After adding the Al-5Ti-1B master alloy, the morphology of the primary α-Al dendritic crystal was changed to a somewhat equiaxed structure or small polygonal as shown in Figure. 4(d,e,f) with reducing the size of the primary α-Al phase obviously. In addition, the average grain sizes at different levels of Al-5Ti-1B master alloy is calculated using quantitatively analyzed software (linear intercept method). The results of these calculation are summarized in Table 3.
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A. A. Khalil, M. H. Alkathafi and R. M. Esmaael
Table 3. Average grain size of α – Aluminium
Al-5Ti-1B 0 1 3 5 ) wt.%)
Average grain size 730 270 255 260 (μm)
The average grain size of A356 without addition of grain refinement was several micrometers. Upon inoculated by Al-5Ti-1B master alloy, the dendritic structure is divided into a somewhat globular grain structure. When adding an amount of Al-5Ti-1B master alloy from 1 to 3 wt. % lead to a decrease in grain size from 270 to 255 μm. However, when the addition increased to 5 wt.% , the grain size is slightly increase to 260 μm, there is no significant grain size difference between different level of Al-5Ti-1B master alloy was observed. The effect of various amounts of Al–5Ti–1B grain refiner on the average grain size of the cast specimens is indicated in Table 3. It can be seen that the increase of Al–5Ti–1B master alloy from 1 to 3 wt.% to the alloy resulted a fine microstructure and almost significant reduction of the average grain size. However, by further addition of grain refiner (5 wt.%) to the alloy, the average grain size almost remains constant and the excess addition of the grain refiner does not have a considerable effect on the microstructure of the alloy. Therefore, the optimum amount of 3 wt.% Al–5Ti–1B was selected for refining of the alloy. The grain size bears an inverse relationship to the number of nuclei presented in the liquid state, and will act as nucleation sites during solidification. Since each grain forms from one single nucleus, as great the number of nuclei presented in the melt, as more grains will be formed, thus their size will be reduced. If the number of nuclei is sufficiently high, dendritic structure could not be formed, as they will have no space to grow, and globular grains will preferentially formed. Furthermore, in the previous researches, which have been carried out on the
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Si-phase
α-Al phase
(a) 0 % Al-5Ti-1B (d) 1 % Al-5Ti-1B
(b) 0 % Al-5Ti-1B (e) 3 % Al-5Ti-1B
(c) 0 % Al-5Ti-1B (f) 5 % Al-5Ti-1B
Figure 4. Optical micrograph of A356 with and without addition of Al–5Ti–1B.
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A. A. Khalil, M. H. Alkathafi and R. M. Esmaael effect of the different amounts of Al–5Ti–1B master alloy in thin section casting (Φ6 mm) of aluminium alloy Al–12Zn–3 Mg–2.5Cu, the optimum amount of Al–5Ti–1B was found to be 1 wt.% by Seyed Ebrahimi [13], and 2 wt.% by Alipour [14]. Others researchers recorded the most significant improvement of microstructure of A356, when adding 2.5 wt.% of the Al-5Ti-1B master alloy[15].
3.3 Mechanical Properties 3.3.1 Mechanical Properties of A356 At Different Levels Of Grain Refinement
The mechanical properties of A356 alloy refined with the different amounts of master alloys (0, 1, 3, 5 wt.%) Al-5Ti-1B were determined and the results are shown in Figures 5 and 6. It is clear that the ultimate tensile strength (σuts), yield strength (σy ) and elongation (δ) of the A356 alloy without grain refinement are correspondingly lower than those of the refined ones. It can be seen that the tensile strength, yield strength and elongation are increased markedly with addition of grain refinement, the tensile strength, yield strength and elongation of the A356 with 3 % grain refine of (Al-5Ti-1B) are 156.3 MPa, 104.3 MPa and 4.9%, respectively, i.e. improvement occurred by 12 %, 6 % and 8.9 % respectively compared with that one’s of non-grain refined. The improvement of tensile properties of the refined A356 alloy can be attributed to the formation of supersaturated solid solution in the solution treatment process and Mg2Si precipitates during aging [15]. It can be seen that the increase of Al–5Ti–1B master alloy from 0 to 3 wt. % can result in a significant improvement of mechanical properties of the A356 alloy. However, the mechanical properties almost remains constant by further addition of grain refiner (5 wt.%) and the excess addition of the grain refiner does not have any considerable effect on the mechanical properties of the alloy. In the previous work [15], which has been carried out on the effect of the different amounts of Al–5Ti–1B master alloy on the mechanical properties of aluminium alloy. The most significant improvement of tensile properties of A356 was obtained by adding 2.5 wt.% of the Al-5Ti-1B master alloy. The main reason for the improvement of the mechanical properties of A356 with addition of grain refinement (Al– 5Ti–1B) may also be due to solid solution strengthening and precipitation hardening. Grain refinement is the key strengthening mechanism for as cast A356 alloys [15]. The increase of ultimate tensile strength, yield strength and elongation values which occurs as a result of grain refinement is 02 Vol.10 (1),18-29,June.2020
Influence of Grain Refinement by Al-5Ti-1B on …... due to grain boundary strengthening mechanism that is best described as Hall–Petch equation
−1 (휎푦 = 휎0 + 푘푦푑 2 ), that demonstrates the yield strength dependence on grain size, d (mm),[16]. These results confirm expectations based on the metallographic results, Figures 5 and 6.
180
160 Tensile 140 Yield
120 MPa
100
80
60 0 1 2 3 4 5 Wt.% Al-5Ti-1B
Figure 5. Ultimate tensile strength and yield strength of A356 alloy refined with different levels of the Al-5Ti-1B master alloy.
5 4.9 4.8 4.7 4.6
4.5 % Elongation % 4.4 4.3 0 1 2 3 4 5 Wt.% Al-5Ti-1B
Figure 6. Elongation of A356 alloy refined with different levels of the Al-5Ti-1B master alloy.
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A. A. Khalil, M. H. Alkathafi and R. M. Esmaael
4. Conclusions
The microstructures, mechanical properties of the refined A356 alloys were investigated by introducing both titanium and boron in the form of Al-5Ti-1B master alloy and the following conclusions can be drawn:
. At the addition of Al-5Ti-1B in aluminium alloy-A356, α-Al phase can be well refined from coarse dendrites to fine equiaxed grains, having an average grain size of 260 µm. . At the addition of Al-5Ti-1B in aluminium alloy-A356, the eutectic silicon remains unchanged in the as-cast A356 alloys. . Enhancement in the mechanical properties such as tensile strength and yield strength were obtained with a significant increase in their values in the case of A356 alloy where grain refiner Al-5Ti-1B were added as compared to that of without grain refinement. . Elongation of A356 alloy refined with different levels of the Al-5Ti-1B master alloy initially increased then slightly decreased.
. The results indicate that a small amount of Al-Ti5-B1 produces the greatest refinement, while no significant reduction of grain size is obtained with a great amount of grain refiner.
References
[1]. Yücel Birol, Grain Refining Efficiency of Al-Ti-C alloys, Journal of Alloys and Compounds, 422 (2006), pp. 128-131. [2]. Pengting Li, Sida Liu , Lili Zhang and Xiangfa Liu, Grain Refinement of A356 Alloy by Al–Ti–B–C Master Alloy and its Effect on Mechanical Properties, Material and Design,47(2013) p522-528 [3]. Vencl A, Rac A, Bobić I, Tribological Behaviour of Al-Based MMCs and their Application in Automotive Industry, Tribology Industry, 26, Jan 2004, pp 31–38. [4]. Amulya B. P., Satyabrat D., Bharat B. J. and Nedumbilly P., Effects of Al-5Ti-1 Grain Refiner to the Microstructure, Mechanical Properties and Acoustic Emission Characteristics of Al-5052 Aluminium Alloy, Journal of Materials Research and Technology,Vol.4,issue 2, 2015, Pages 171-179. [5]. Hong-Liang Zhao, Jin-Sheng Yue,Ya Gao and Kang-Rong Weng, Grain and Dendrite Refinement of A356 Alloy with Al–Ti–C–RE Master Alloy, Rare Met.(2013), 32(1), pp.12–17.
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[6]. Apparao KC and Birru AK, Influence of Grain Refiner and Modifier on the Microstructure and Mechanical Properties of A356 Alloy, IOP Conf Series: Materials Science and Engineering, Vol. 303, 2018, p. 012012. [7]. Bannaravuri P.K., Birru A.K., Strengthening of Mechanical and Tribological Properties of Al-4.5%Cu Matrix Alloy with the Addition of Bamboo Leaf Ash, Results in Physics, Sep.2018,Vol.10:pp.360–373. [8]. Polmear I.J., Light Alloys From Traditional Alloys to Nanocrystals, Fourth Edition, Melbourne, Australia, 2006, pp. 205-216. [9]. Zhongtao Z., Jie L., Hongyun Y., Jian Z. and Tingju L., Microstructure Evolution of A356 Alloy Under Compound Field, Journal of Alloys and Compounds, Vol.484,2009, pp. 458–462. [10]. Annual Book of ASTM Standard, 2006, “Metals Mechanical Testing; Elevated and Low Temperature Tests; Metallography “, USA. [11]. Puga, H., Costa, S., Barbosa, J., Ribeiro, S., and Prokic., M., Influence of Ultrasonic Melt Treatment on Microstructure and Mechanical Properties of AlSi9Cu3 Alloyʼʼ, Journal of Materials Processing Technology, 2011,pp. 1-7. [12]. Das, A., and Kotadia., H.R., Effect of High-Intensity Ultrasonic irradiation on the Modification of Solidification Microstructure in a Si-rich Hypoeutectic Al–Si Alloy, Materials Chemistry and Physics, Vol. 125, 2011,pp. 853-859. [13]. Seyed Ebrahimi, S.H., Emamy M., Effects of Al–5Ti–1B and Al–5Zr Master Alloys on the Structure, Hardness and Tensile Properties of a Highly Alloyed Aluminum Alloy, Materials and Design 31(1),Jan 2010, pp. 200–209. [14]. Alipour M., Emamy M., Effects of Al–5Ti–1B on the Structure and Hardness of a Super High Strength Aluminium Alloy Produced by Strain-Induced Melt Activation Process, Materials and Design, Vol. 32, 2011,pp.4485–4492. [15]. Zhu M., Yang G., Yao L., Cheng S., and Zhou Y., Influence of Al-Ti-B Addition on the Microstructure and Mechanical Properties of A356 alloys, Rare Metals, Vol. 28, No. 2, Apr 2009, pp. 181 -188. [16]. Shabani M.J., Emamy M., Nemati N., Effect of Grain Refinement on the Microstructure and Tensile Properties of Thin 319 Al Castings, Materials and Design, Vol. 32, 2011, pp. 1542-1547.
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K. Khalifa, M. Bughazem, I. Saleh, and M. Alghool
Sirte University Scientific Journal (Applied Sciences) Vol.10 (1), June 2020
Theoretical Study of Producing Sustainable Electrical Energy via Hydraulic Energy
K. Khalifa, M. Bughazem, Imahmed M. Saleh, and M. Alghool
Mechanical Engineering Department, Faculty of Engineering, Sirte University, Libya
Abstract
Over the last decade, the Libyan National Power Grid has significantly suffered from negligence and vandalisms, which led to severe materialistic damage to power generation units, transmission networks, distribution subsystems and power plants fuel shortage. These happen because of the security incidents and armed clashes within the country. This has placed the electrical power grid in a difficult and critical situation leading to a large deficit in meeting the demand for electricity use, therefore consequence to power cuts for long time.
However, the Libyan Man-Made River LMMR is considered as the world largest irrigation project, consisting of a large network of pipes that supplies water from Libyan Desert in the south to the coastal areas in the north. This water movement crossing mountains and various land orientations from the south to the north of the country has a huge kinetic energy as a result.
This paper is examined the possibility of taking advantage of the water flow energy through the Libyan western mountains to generate energy (producing electricity through water movement) by using an appropriate size of turbine. The work has been theoretically undertaken the opportunity of producing a clean and relatively cheap energy in the area of Abuzian near Tarhuna city. Moreover, the research is based-on realistic currently available data in term of the water flow-rate, the pipe diameter, the area orientations, and the pipeline slopes as well as the dimensions of the existing reservoirs. In summary, this research on the proposed area has suggested the required designs and calculations for selecting a turbine and an appropriate generator. As a result, the research has showed promising potential of producing 39.5 MW of the turbine power output and a net electrical producing energy of 29 MW and the generator overall efficiency is 73% through this area in the west of Libya.
Keywords: Libyan Man-Made River (LMMR); sustainable development; renewable energy; Hydro- kinetic;
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1. Introduction and Background
The Libyan Man-Made River (LMMR) is a network of pipes that supplies water from the Sahara Desert in the south of Libya to the northern regions for using it in irrigation and domestic purposes. It is considered as the world's largest irrigation project. It consists of more than 1,300 wells, more than 500 m deep in the source regions, and supplies 6,500,000 m3 of fresh water per day to the cities on the cost. The project's construction was divided into four essential phases [1]. As part of the LMMR project huge concrete reservoirs were constructed in various parts of the country; Some of which supply water to the various lines used to regulate and provide on demand potable water, while other reservoirs were constructed in circular open lakes, which are more than one km in diameter, for agricultural purposes. In fact, it is about 70% of the water conveyed by the project intended for agricultural purposes, while the remaining amount is for domestic consumption throughout the year. The main reservoirs are include the following: Ajdabiya Reservoir (storage: 4 million cubic meters) Omar El-Mokhtar Grand Reservoir (storage: 24 million cubic meters) Omar Elmokhtar reservoir (storage: 4.7 million cubic meters) Ghordabiya Reservoir (storage: 6.8 million cubic meters) Ghordabiya Grand Reservoir (storage: 15.4 million cubic meters) Abuzian Reservoir (storage:300,000 m3 daily online storage)[2]
Figure 1. Libyan Man-Made River (LMMR) stages and reservoirs [4]
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K. Khalifa, M. Bughazem, I. Saleh, and M. Alghool
2. Research Geographic Area and Orientation
2.1 Tarhunah-Abu Ziyyan Orientation The Tarhunah-Abu Ziyyan Project is designed to supply 800,000 thousand cubic meters of water per day from the regulating tank at Tarhunah to the 300,000 m3 concrete Abu Ziyyan storage reservoir. The Project includes conveyance of 1.2m to 2.8m diameter pre-stressed concrete cylinder pipe (PCCP) with an overall length of 106 km terminating in a steel pipeline connection rise of 500m to the top of the escarpment. There are also two pump stations, break pressure tank and 6 major turnouts [3].
2.2 Abu Ziyyan ReservoirDesign Specifications As a part of area interest, based on the elevation of the Abozian reservoir, the surface of the earth to the highest point in the reservoir (500 m) and based on the topography of the mountain, the site of the turban was selected (724m) horizontally from the reservoir. The length of the pipe was determined from the reservoir to the site of the turban (880 m) and (55 degrees) [5].
3. Turbine and Generator Design
Basically, the fundamentals of water power remain the same. Water flows across the turbine, turning a shaft connected to a generator that produces electricity. Nowadays, hydro power is mostly used to generate electrical energy on large scale by collecting water in large reservoirs or dams and it is called hydroelectric power. Turbines placed on the path of the flowing water extract its kinetic energy and convert it to mechanical energy causing the turbines to rotate at high speed. It drives a generator that converts the mechanical energy into electrical energy [6, 7].
3.1 Pelton Turbine Design Specification
This involves the calculations and measuring the net head and the water flow rate. [8]
The Net Head or the Effective Head (He) He = Hg − Hi Where:
Hg: is the gross head that is the vertical distance between water surface level at the intake and at the turbine (m) and this is estimated to be 500 m from the ground level in the selected area.
Hi: is the total head loss during the transit of water from the headrace to tailrace, which is mainly head loss due to friction, and is given by:
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퐿 푉2 H = 푓 ∗ ∗ i 퐷 2푔 Where: 푓: is the coefficient of friction of penstock depending on the type of material of penstock. 퐿: is the total length of penstock = 880m 퐷: is the diameter of penstock and = 1.2m 푚 푉( ): is the mean flow velocity of water through the penstock and is calculated as: 푠 Q 푉 = A The flow rate (Q) = 9.25 m3/s The diameter area of pipe 휋 3.14 A = 퐷2 = 122 = 1.1304 푚2 4 4 Then the flow velocity of water through the penstock: Q 9.25 m V 8.18 A 1.1304 s
To calculate the coefficient of friction of penstock ƒ푐, the Reynolds number need to be calculated as the follow: Reynolds Number (Re) The dimensionless Reynolds number plays a prominent role in foreseeing the patterns in a fluid’s behaviour. The Reynolds number, referred to as Re, is used to determine whether the fluid flow is laminar or turbulent. It is one of the main controlling parameters in all viscous flows where a numerical model is selected according to pre-calculated Reynolds number:
ρ ∗ V ∗ D 푅푒 = µ
9988.181.2 Re 9.6106 1.01103 Relative Roughness (RR) The quantity used to measure the roughness of the pipe’s inner surface is called the relative roughness, and it is equal to the average height of surface irregularities (ε) divided by the pipe diameter (D).
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K. Khalifa, M. Bughazem, I. Saleh, and M. Alghool
Figure 2. Relative Roughness in a Pipe
ℰ 푅푅 = D
Where both the average height surface irregularities and the pipe diameter are in millimeters: 3104 RR 0.00025 1.2 If we know the relative roughness of the pipe’s inner surface, then we can obtain the value of the friction factor from the Moody Chart.
Figure 3. Moody Chart
The Moody chart (also known as the Moody diagram) is a graph in non-dimensional form that relates the Darcy friction factor, Reynolds number, and the relative roughness for fully developed flow in a circular pipe, as follow:[9]
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Table 1. Absolute Roughness for Different Materials
Material Absolut Roughness(mm) Copper, Lead, Brass, and Aluminum 0.001-0.002 PVC and plastic pipes 0.0015-0.007 Weld steel 0.045 Carbon steel 0.02-0.05 New cast iron 0.1-1 Wood stave 0.25-1 Smoothed cement 0.3 Ordinary concrete 0.3-1 Concrete Rough from marks 0.8-3
The friction factor the value ƒ푐 = 0.015, so that the head loss is
퐿 푉2 0.015 ∗ 880 ∗ 8.182 H = ƒ ∗ ∗ = = 37.5 푚 i 푐 퐷 2푔 1.2 ∗ 2 ∗ 9.81
So, the effective head (He) can be obtained as:
He = Hg − Hi= 500 – 37.5= 462 m Turbine Input Power (Pti) The hydraulic input Power to the turbine in (Watt) can be calculated as: 2 Pti = ρ ∗ g ∗ 퐶 n ∗ He ∗ 푄 Cn nozzle (jet) discharge coefficient ≈ 0.98 2 Pti = 998 ∗ 9.81 ∗ 0.98 n ∗ 462 ∗ 9.25 = 40 푀푊 Specific Speed (Ω풔) However, the calculation of the specific speed, the shaft speed is required. Since hydraulic turbines are used for electricity generation, the shaft speed must be synchronous with the frequency of the electric current. With some exceptions the frequency is 50 Hz in Europe and Asia and 60 Hz in North and South America. To obtain the proper value for the line frequency, the shaft speed is: 120 f N 2P
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Assume the number of poles on generator (P = 5) 12050 N 600rpm 25 Specific speed (Ωs) Q s 3 (g H ) 4 e 2 N 62.8rad / s 60 62.8 9.25 s 3 0.34 (9.81 462 ) 4 e Table 2. Power Specific Speed Ranges of Hydraulic Turbines
Type Ω풔 휂% Single jet 0.02 - 0.18 88-90 Twin jet 0.09 - 0.26 89-92 Three jet 0.10 - 0.30 89-92 Four jet 0.12 - 0.36 86
The recommended number of jets (n) is the value of 4. Hence the discharge from each jet is: Q Q 2.31 m3 / s n Ideal velocity of the jet from the nozzle:
V2 2 g He And actual velocity of jet:
V2 Cn 2 g He 0.98 29.81 462
V2 93.30 m/ s
Cn coefficient of the velocity for nozzle is in the range of 0.97 to 0.99 The diameter of the jet: 4Q d jet n V 1
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Theoretical Study of Producing Sustainable …...
49.25 d jet 43.1493.30
d 0.17 m jet And the blade speed (U) is: U = 0.45 × V1 = 42 m/s
Therefore the diameter of the wheel (Dw) is: 2U 2 42 Dw 1.33m 62.8 And the number of buckets is: D 133 Z w 15 15 18.9 19 2 d 217 jet Clearance between the nozzle and buckets is:
푋푛푏 = 0.625퐷푤 = 0.83 푚
Bucket Dimensions The bucket axial width can be calculated as:
퐵푤 = 3푑푗푒푡 = 0.51푚 The bucket radial length can be calculated as:
퐵푡 = 2푑푗푒푡 = 0.34 푚 The bucket depth can be calculated as:
퐵푑 = 0.8푑푗푒푡 = 0.13 푚
Figure 4. Bucket Dimensions
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K. Khalifa, M. Bughazem, I. Saleh, and M. Alghool
The bucket volume was given as: 3 3 푉푏 = 0.0063퐷푤 = 0.014푚
3.2 Force, Power and Efficiency of a Pelton Wheel
The inlet and outlet velocity triangles for Pelton wheel turbine is as shown in figure below. As the runner diameter is same at inlet and outlet, tangential velocity of wheel remains the same. In practical case the relative at the outlet is slightly less than that at inlet due to frictional loss over the inner surface of the bucket. Some velocity is also lost due to the jet striking over the splitter. Hence:
푊3 = 퐶푏푊2
Where Cb is bucket velocity coefficient.
Figure 5. Velocity Triangles for Pelton Wheel Turbine
From inlet velocity triangle,
푉2 = 푉푢2 푊2 = 푉2 − 푈 From outlet velocity triangle,
푊3 = 퐶푏푊2 03 Vol.10 (1),30-42,June.2020
Theoretical Study of Producing Sustainable …...
푉푢3 = U + 푊3푠푖푛훽3 = U + 퐶푏푊2푠푖푛훽3
The work done by Pelton wheel jets is:
w = U(푉푢2 − 푉푢3) Substituting:
푊2 = 푉2 − 푈 , gives w = U (푉2 − 푈) (1 − 퐶푏푠푖푛훽3)
Power output by the wheel is,
푃퐻 = 휌푄푈(푉2 − 푈)(1 − 퐶푏푠푖푛훽3) 푃퐻 = 1000 ∗ 9.25 ∗ 42(93.3 − 42)(1 − 0.98 ∗ sin(−90)) 푃퐻 = 39.5 MW
3.3 Generator Design
If the speed is slow, the numbers of poles is high. The overall power (s) in (kV.A) is calculated as: [10] 푠 = √3 ∗ 퐼 ∗ 푉 While the active power (p): 푃 = √3 ∗ 퐼 ∗ 푉 ∗ cos 훼 Where: ⍺ is cablence factor While the reactive power (p): ∅ = √3 ∗ 퐼 ∗ 푉 ∗ sin 훼 The regulated voltage applied in Hydropower are: (0.38, 6.5, 10.5, and 11) kV for 50Hz. In most countries the generators in water stations are made to work on voltage between (10.5 to 15 kV) and on the current between (250 to 1500 A). For the resistances for stator and rotor are as follow:
푅푆 = 0.012 ∶ 0.5 Ω 푅푟 = 0.03 ∶ 0.5 Ω The efficiency factor for big machines is between (0.97-0.98) and for small machines is 0.95. The cooling-system is applied using either air-water or water-solvent or water- Hydrogen systems. For the generator which runs in the water stations: T = 605 KN.m, Pout = 39.5 MW, N = 600 rpm, Power factor = 0.8, Nominal Voltage (Vn) = 10.5 Kv Nominal Current (In) = 2 KA and Rs (Stator Resistance) = 0.01 푠 = √3 ∗ 퐼 ∗ 푉 03 Vol.10 (1),30-42,June.2020
K. Khalifa, M. Bughazem, I. Saleh, and M. Alghool
푠 = √3 ∗ 2 ∗ 10.5 = 36.33푀푉퐴 The generator is selected on (SW36.33/10.5), and has the following specification: Xq = 0, Xd = 0.5, and R = 0.0012 Ω. The copper losses of stator (Pcu) are: Pcu = I2*R = (2000)2 (0.0012) = 0.048 MW P stray losses + Pmech+ Pcore = 1.1 MW
Assume that:
Pcu + Pstray losses + Pmech+ Pcore = 0.048+ 1.1 = 1.148 MW P out = S * cos 훼 = 29.06 MW
Pin = Pout + Pin = 29.06 + 1.148 = 30.208 MW
The copper losses of rotor will be neglected because the rotor is supplied by another DC source. Therefore, the efficiency is:
푃 29.06 휂 = 표푢푡 = = 0.96 푃푖푛 30.208
Then the appropriate power transformer can be selected as the following: The power lines that connected to the generator must be equal to power of generator, so it can be selected from table below and they have their own technical specification. The calculation data of transmissions line (35-110) KV for 100 Km.
Table 3. The Generator Specifications Cross section R0,0M, 35Kv 110Kv Area(mm2) +20 0C X0,om X0,OM B0,10 cm q0,mvar AC70/11 42.8 43.2 44.4 2.55 3.40 AC95/16 30.6 42.1 43.4 2.61 3.50 AC120/19 24.9 41.4 42.7 2.66 3.55 AC150/24 19.8 40.6 42.0 2.70 3.60 AC185/29 16.2 - 41.3 2.75 3.70 AC240/32 12.0 - 40.5 2.81 3.75
The working transform that has been selected is to transfer the voltage from 10.5 to 35 KV and the transport lines cross section area = 240/32 and has the following specifications: 33 Vol.10 (1),30-42,June.2020
Theoretical Study of Producing Sustainable …...
Ro = 12 Ω /100 km Xo = 40 Ω /100 km
Hydraulic Generator High Voltage Low Voltage Distribution Turbine Transformer Transformer
Generate 29 MW 10.5kV to 35 kV
Transport line Resistance for distance (1 km)
12 ⁄ 푅표 = ⁄100 = 12 km
The power in both sides of transporter must be equal
P1 = P2 I1 ∗ V1 = I2 ∗ V2 2KA ∗ 10.5KV = 퐈ퟐ ∗ 35KV 10.5KV I2 = (2퐾퐴 ∗ ⁄35KV) = 0.6퐾퐴
Calculation of consumed power in line:
P = I2 ∗ R 2 ⁄ 푃 = (0.6퐾퐴) ∗ 0.12 km = 43.2퐾푊
Multiply in 3 to find three phases: 3 ∗ 43.2퐾푊 = 129.6퐾푊
The net power at the pump station is: 29000퐾푊 − 129.6퐾푊 = 28870.4퐾푊
The efficiency of power plant is:
P 29 η = E + = 73% PH 39.5
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K. Khalifa, M. Bughazem, I. Saleh, and M. Alghool
4. Conclusions
LMMR is considered as the world's largest project that transports drinking water from the Sahara in the south to the coastal cities and villages in north of Libya; this natural water movement toward the north has the potential energy to produce a clean, safe, sustainable and renewable energy. This paper has examined the possibility of utilizing water kinetic energy and showed the great potential of producing an electrical energy through the area of Abu Ziyyan Mountain in the west of the country. As a result, based on the theoretical method supported with real data (water flow- rate, land orientation, pipes and reservoirs geometries), this research has showed the massive chance of producing 39.5 MW of the turbine power output and a net electrical producing energy of 29 MW and the generator overall efficiency is 73% through this area in the west of Libya.
References
[1] Libyan Great Man-made River,https://www.temehu.com/great-man-made-river-gmmr obtained 1/1/2020. [2] Great Man-made River, https://www.great-man-made-river.algaddafi.org/great-man-made-river-gmmr-- facts-figures obtained 7/1/2020. [3] Hydro Power Projects: Social and Environmental Perspective http://www.socialissuesindia.wordpress.com/,obtained 5/1/2020 [4] Libyan People Bureau, www.libyanpeoplesbureau.com/manmaderiver.html, obtained 1/3/2020 [5] Nasar M. N., 2015 Survey of Sustainable Development to Make Great Man-Made River Producing Energy and Food. Curr World Environ 2015; 10 (3) ISSN: 0973-4929 [6] Reinertsen K, 2008, Pelton Model Water Power “The International Journal of Hydropower and Dams (2008). [7] Ghazali, A.M., Abounahia, M.A. 2005, An Optimum Approach For The Utilization Of The Great Man- Made River Water In Libya. In Ninth International Water Technology Conference, 497-508 (2005). [8] Manjunatha N, Kuldeepak Kumar, Thammaih Gowda, 2016, Design of a Pelton Wheel Turbine for a Micro Hydro Power Plant”. 5th international Conference on Sciences Technology and Management, in Indian International centre 2016. [9] V.M Prajapati, R.H Patel and K.H Thakkar, 2015, Design, Modeling& Analysis of Pelton Wheel Turbine Blade, IJSRD - International Journal for Scientific Research & Development Vol. 3, Issue 10, 2015 | ISSN (online): 2321-0613. [10] Niklywat, 1994, Design Electrical Stations and Substations Handbook, Moscow (1994).
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Performance Evaluation of Feed Forward Neural …...
Sirte University Scientific Journal (Applied Sciences) Vol.10 (1), June 2020
Performance Evaluation of Feed Forward Neural and Recurrent Neural On Real System Dataset of Robot Execution
Ali.k. Diryag1, Nasar A. Ali2, kaled M. Legweel3 [email protected]
1,2Department of Mechanical Engineering, Faculty of Engineering, Sirte University, Libya 3 Faculty of Engineering science & Technology, Sabha, Libya.
Abstract
This article presents approach based on the artificial neural networks (ANN). It is employed to evaluate of performance real date set of real system. The training and testing dataset used in the experiment consists of forces and torques memorized immediately after the real robot failed in assignment execution. Two types of neural networks (NN) are utilized in order to find best performance method - feed forward neural networks (FFNN) and recurrent neural networks (RNN) and an additional evaluation would be to run test sets for each neural network to see how small an error is produced. Moreover, we investigated 24 neural structures implemented in Matlab software. The obtained results confirm that this approach can be successfully applied in this domain.
Keywords: Artificial Neural networks, Recurent nural, Feedforward nural, real system.NN strectuers, Proformance,
1. Introduction
Artificial Neural networks (ANN) [1] is one of the five main computational intelligence paradigms [2], and are a well-known tool used as a solution for various problems in almost all areas of engineering . They can understand the mapping between data during the training process using different learning algorithms. They can automatically define classification schemes. Artificial neural networks have great capabilities to generalize, cluster or organize data, deal with uncertainties, noisy data, and non-linear relationships [3]. The researchers of artificial neural networks presented the model of multilayer Perceptron network to resolve these problems [4]. The first and most popular network is the feed forward network; the second is the recurnt network. ANN have been nonlinear systems. Hidden patterns, which could be
34 Vol.10 (1),43-51,June.2020
A.k. Diryag, N. A. Ali, k. M. Legweel independent of any mathematical models, can be found from the training data sets. If the same or similar patterns are met, ANN come up with a result with minimum mean square error (MSE). For this purpose, Matlab is chosen as an experiment environment to perform the required computations and visualizations. To describe a neural network’s structures adequately, it is necessary to specify how many layers it has, each layer’s transfer function, the number of neurons in each of them and to characterize how layers are interrelated [5]. The application of neural networks in the science and engineering research has recently garnered attention in the literature [6,7, 8 ]. The objective and main aim of the paper is, therefore, to develop a neural network model ,To be able to evaluate the ability of FFNN and RNN Artificial Neural Networks. To examine the best structure of neural networks (for a given data set) . In this study, FFNN and RNN structures have been employed, and also presents performance comparison of different structures.
2. Theoretical Framework
1.1 Feed Forward Neural Network (FFNN)
(FFNN) allow signals to travel one way only, from input to output .there is no feedback (loop) .the output of any layer does not affect that same layer. They are extensively used in pattern recognition.
2.1.1 Multilayer Feed Forward Networks (MLFF)
The MLFF network is a member of the feed forward network architecture, and is the simplest of the networks under investigation.( MLFF) has a layered structure with more layers of nodes called hidden layers between the inputs layers and the output layers In this network, there are layers, each composed of neurons.. The input layer with a linear activation functionis fed the input values which are then multiplied by an input weight matrix, passed through the hidden layer (using the sigmoid activation function), multiplied by an output weight matrix, and finally fed to the output layer which uses a linear activation function.
2.2 Recurrent Neural Network (RNN) The RNN is similar to the MLP in general structure except that it contains a feedback loop with unit delay from some later stage of the network back to the input layer. In this paper, Elman network is used which takes the output from the hidden layer. There are numbers of special cases of RNN such as, Elman [9], Jordan [10] and Hopfield [11]...etc. In this paper, the Elman RNN will apply for neural structures to test in software environment so as to find optimal solution
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2.2.1 Elman Recurrent Neural Network (Elman RNN) The Elman network is one type of the partial recurrent neural networks, it was introduced by Elman [9]. The Elman RNN in this study due to the hidden layer being wider than the output layer. This wider layer allows more values to be fed back to the input, thus allowing more information to be available to the network.
3. Data and Methodology
3.1 Description of Data Sets
The data used in this paper is obtained from a real system. This data is available via well-known machine learning repository [12], and refers to the evolution of forces (퐹) and torques (푇) during execution of a specific task. In order to correctly evaluate and compare various structures, the robor excution failures in approach to grasp position are considered. Each feature in the dataset represents a force or torque value measured immediately after failure detection. Total number of instances is 88, and each instance consists of 15 sensor measurements (i.e. samples) collected at regular time intervals. Three values of forces and torques are founded in each sample; therefore, one instance has 90 different features (i.e. the values of (퐹) and( 푇).
In the dataset, 4 different robot situations (i.e. data classes) can be identified: normal, collision, obstruction and front collision with the distribution of 24 %, 19 %,, 18 %, and 39 %,, respectively. The identification of particular class is based on the values and relationships between measured forces and torques.
3.2 Artificial Neural Network (ANN) Modelling.
In this study 24 , different structures were investigated, including the networks with one, two or three hidden layers. The feedfowrd network structure in Figure (1) as 3-2 means that there are 3 neurons in the first hidden layer, 2 in the second hidden layer. The NN input and output are single column vectors since they represent scaled values of recorded measurements and corresponding to situations.
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A.k. Diryag, N. A. Ali, k. M. Legweel
Figure 1. Feedfowrd (NN) Structure
In this paper, according to the above strategy for varying of different network structures and based on the program package MatLab, the following network structures are listed in table 1.
Table 1. Network Structures Three- one-layered Two-layered. four-layered No. No. No. layered. No. 1 1 7 1-1 13 2-2-2 19 3-3-3-3 2 2 8 2-2 14 3-2-2 20 4-3-3-3 3 3 9 3-2 15 4-3-2 21 5-4-3-3 4 5 10 5-2 16 5-3-2 22 8-5-4-3 5 8 11 8-4 17 8-3-2 23 10-8-4-3 6 10 12 10-4 18 8-4-2 24 10-8-5-4
As mentioned, the NN input parameters are defined by the force and torque. On the other side, the grasp position conditions (normal, collision, obstruction or front collision) have been taken as an output parameter. Artificial neural network has to be trained with corresponding data in order to learn the functional relationships between input and output data pairs. In this paper, each one of these 24 different network structures has been trained with two training algorithms: Levenberg-Marquardt (LM) [13, 14] and Elman respectively. The sigmoid activation function has been used in hidden layers (1) and linear in output layers (2).
1 푓(푥) = . (1) 1+ 푒−푥
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푓(푥) = x . (2)
In addition, The NN performance is evaluated using the MSE (3).
1 푁 MSE = ∑ (T − Y ) . (3) 푁 푖=1 i i
Where N is number of data, T is the target and Y is the output. Figure 2. Presents an example of LMFF training implantation in Matlab® software
Figure 2. LMFF Training In MATLAB®
4. Results and Discussion
Based on the networks’ capabilities, it is possible to find which network structure shows the performance results versus influence of the learning algorithm. The Matlab is used for implementation and testing. In order to find optimal NN, The total number of 24 different structures and architecture has been tested several times, In order to find optimal NN to evaluate their capabilities for generalizing the performance under different conditions. The testing results in terms of MSE on test data which is 30% of the dataset for LMFF and Elman RNN in are given in Figure 3 and figure 4, respectively. The NN structurers in the figures
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A.k. Diryag, N. A. Ali, k. M. Legweel
Figure 3. LM Feed forward Testing
Figure 4. ELMAN RNN Testing
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Performance Evaluation of Feed Forward Neural …...
represent network number given in table 1.The testing results by means of Mean Squared Error (MSE) for (LMFF) and Elman (RNN). It is obvious that the MSE for LM has the decreasing trend when number of neurons and layers increases. In other words, the larger number of neurons and layers has positive influence on the training process . As it is obvious from Figure.3 and Figure.4, the (LMFF) showed overall better results. Smallest MSE was reported for structure No. 23 in Table 1, and the MSE is 0.0023. In the case of Elman Neural Network, the similar conclusion can be obtained. Overall, the NN with 1 hidden layers and show the best performances. Particularly, in the case of Elman algorithm, the network number 6 (table 1) has the smallest test MSE and was reported for ([10] ) structure (is equal 0.0539).
Figure 5 shows, respectively, screen captions of the LM NN training windows obtained using the toolbox in MATLAB®. The output tracks the targets very well for training, testing, and validation, and the R-value is over 0.96 for the total response. and for the Elman NN ,the validation and training plots are shown in Figure 6. The LMFF show overall better results than Elman RNN. Smallest value of MSE was reported for [10-8-4-3] structure (see Table 1).
Figure 5. LM FF Training Windows
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A.k. Diryag, N. A. Ali, k. M. Legweel
Figure 6. Validation And Training Of Elman RNN
5. Conclusions
This paper has shown the properties of two types of ANN, namely feed- forward NN and recurrent NN that have been trained with the real data to evaluate the performance and ability of ANN. In this papar , The efficiency of the Elman RNN was compared with the MLFF (multi-layer feed forward) .Asuccessful mapping from the execution forces and torques to the 4 possible cases that correspond to the particular input (normal, collision, obstruction or front collision) is developed using NN. The training dataset consists of a real system of robot that is recorded immediately during the execution of the specific task. In order to fully show the robustness of the approach. Results through networks show usefulness and the applicability for the evalution of the proposed approach in terms of training error.
References
[1] L .P. VeeLenturf. Analysis and applications of artificial nural networks .Prentice Hall international Uk Ltd. 1995 [2] G. K. Venayagamoorthy , "A Successful Interdisciplinary Course on Computational Intelligence", IEEE Computational Intelligence Magazine - A special issue on Educational Issues on Computationa lIntelligence, Feb. 2009, pp. 14-23. [3] Krose, B. and van der Smagt, P .. An Introduction to Neural Networks, 8th Edition, The University of Amsterdam , Amsterdam , 1996 [4] M, T, Hagan, H,B. Demuth, M. H, Beat, Neutral Networks Design, PWS ,Beston, 2005
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[5] Li, Y., Powers, D. and Wen, P.: An improved training approach for feedforward neural networks. http://david.wardpowers.info/Research/AI/papers/200002-sub-LSBNN.pdf [6] Murat Kayri. “Predictive Abilities of Bayesian Regularization and Levenberg–Marquardt Algorithms in Artificial Neural Networks”: A Comparative Empirical Study on Social Data. Math. Comput. Appl. 2016 [7] Salihu . ,A. , Garko. “Evaluating Feedforward And Elman Recurrent Neural Network Performances In Time Series Forecasting” Indian Journal of Pure and Applied Mathematics · June 2015 [8] Richard L. W, M. R, and Venayagamoorthy. “Comparison of Feedforward and Feedback Neural Network Architectures for Short Term Wind Speed Prediction”. International Joint Conference on Neural Networks, Atlanta, Georgia, USA, June 14-19, 2009 [9] Elman, J, L. Finding structure in time. Cognitive Science,14,179 211.[Cited on p.48.],1990 [10] M. Jordan, “Serial order: A parallel distributed processing approach, ”Adv. Psychol., 1997 [11] D. Tank and J. Hopfield, “Neural computation by concentrating information in time,”Proc. Natl. …, 1987. [12] http://www.ics.uci.edu/~mlearn/MLRepository.html. [13] Fun, M.-H. and M. T. Hagan,” Levenberg-marquardt training for modular networks,"Proceedings of the 1996 International JointConference on Neural Networks, 468{473, 1996 [14] Hagan, M. T. and Menhaj M. B., “Training feed forward networks with the Marquardt algorithm”, IEEE Transaction on Neural Networks, 5(6), 1994, pp 989-993.
45 Vol.10 (1),43-51,June.2020
Aesha F. R. Amhamed
Sirte University Scientific Journal (Applied Sciences) Vol.10 (1), June 2020
Quality Assay Measurements of Groundwater in Wadijarif–Sirte-Libya Aesha Farag Rahel Amhamed [email protected]
Department of Botany, Faculty of Sciences, Sirte University, Libya
Abstract
Sirte is a city that lies on the coast of the Mediterranean Sea being overwhelmed by the arid or the semi-arid climate. Across the extension of this city, there are several valleys descending from south to the north to be pouring into marshes across the long coast. The collected samples are subjected to different analyses, in order to conduct hydrochemical and bacteriological study of the study area, Chemical analyses have been conducted on those wells samples in terms of determining the concentration of main ions (Chloride Cl-, potassium K+, sodium
Na+, sulfate SO42-, carbonate CO32-, bicarbonate HCO3--, Silicon Si4+, manganese Mn2+, Barium Ba2+, magnesium Mg2+, calcium Ca2+, nıtrate NO3-, NH4+, Alkalinity, electrical conductivity, acidity, pH and total dissolved solids TDS) and bacteriological analysis .For drinking, this groundwater are classified as very poor and unsuitable, furthermore, all analyzed samples for bacteriological content classified as contaminated and classified as unsafe too. Results showed that the concentration of (TDS) has been higher in wells. The increase in (TDS) in wells extending from south to the north, since (TDS) concentration and other ions were increasing the more we are coming close to the sea being a result of the sea waters' invasion. The study has come to the results that these waters are not suitable for drinking before treatment, because the rate of the total dissolved solids and ions are critically high. The wells ones which is an outcome of seawater leakage.
Keywords: Sirte, Wadijarif, Hydrogeology, Groundwater quality, assessment, chemical analysis, bacteriological analysis 1. Introduction
Water is an essential commodity to mankind, and the largest available source of fresh water lies underground. As the world’s population increases, the demand for fresh water has stimulated for the development of underground water supplies. Inevitably, progresses in the form of modernization and urbanization have magnified the problem of the search for fresh water supplies. Efforts have increased to solve these problems; methods for investigating the occurrence, patterns, and movement of groundwater have been improved, better means for extracting groundwater have been developed, principles of conservation have been established, and research of several types has 25 Vol.10 (1),52-63,June.2020
Quality Assay Measurements of Groundwater …... contributed to a better understanding of the subject (Todd, 1963). Groundwater is an essential part of life; it is a vital source of water for domestic, irrigation and industrial uses in both urban and rural areas. The physicochemical and chemical properties of the groundwater determine its quality and suitability for irrigation and human consumption. The potential of groundwater is largely influenced by the specific geologic settings of the area (Elango and Kannan, 2007; Manimaran, 2012; Parihar et al., 2012; Tmava et al., 2013). Groundwater is generally polluted;the pollution of groundwater regime is not only due to sub- surface waste disposal, but is also attributable to the seepage of contaminants from impoundment of toxic waste on unlined surfaces such as indiscriminate spraying of insecticides, pesticides and excessive use of chemical fertilizers etc. (Edmunds, 2003; Thangarajan, 2007; Abdul Jameel et al., 2012; Mumtazuddin et al., 2013). Arid regions have being featured with strong solar radiation, intensive evaporation, significant temperature variations and frequent sand storm, which result in vulnerable environment, particularly water environment due to the insufficiency and non-uniformity of precipitation. Therefore scientific and comprehensive insight into the water resources and environment in such a region is important for water sustainability (Sen, 2008(. The rate of population growth in Libya is considered a high rate and creates a demand for water at a great rate and one of the most important reasons that led to the emergence of the problem of water scarcity. This added to the great diversity in the water demand for the versatility that characterized recent decades, which covered all aspects of life (Mohamed, 2014). Groundwater is an important water resource in both the urban and rural areas of Libya for domestic as well as for agriculture purposes (Kumar et al., 2014). Libya as many other regions under arid climates suffer from inadequate water resources to cover all the needs of this rapidly developing country (Elgzeli, 2010). The Libyan coastal area, south of the Mediterranean Sea, is among one of the different types of water systems, which has a common and specific water characteristic (El-Ghawi, 2005). The intrusion of salt seawater is a groundwater pollution problem in many coastal cities and towns (Kumar et al., 2014).
2. Materials and Methods
All the samples brought from the field were subjected to chemical analysis, aimed to determine the concentration of the following ionized elements: Sodium (Na+), Potassium (K+),Calcium (Ca+2), +2 - -2 -2 Magnesium(Mg ),Chloride (Cl), Bicarbonate(HCO3 ), Carbonate (CO3 ), Sulphate (SO4 ), NO3, NH4 and others minor ions Sr, Mn, Si, Ba. In addition to the cation and anion determination, the electrical conductivity (EC), the total dissolved solids (TDS), pH and the Alkalinity (CaCO3 mg/l) have been measured. Doubled check measurements of borehole depth (m), groundwater depth below ground (m), and converted groundwater elevation from the Sea Level (m) and water temperature T (°C) have also been taken at the site during field work 25 Vol.10 (1),52-63,June.2020
Aesha F. R. Amhamed
Chemical Analysis The analyses of water samples were carried out according to the standard methods for examination of water and wastewater [2]. pH The pH was measured using BOECO PT-370 pH/mv meter, Germany. Electrical Conductivity (EC) It is measured using ATC bench electric al conductivity meter, HANNA, model HI 8820. The standard unit of electrical conductivity is the reciprocal of the resistance in Ohms and is written in terms of microseimens per centimeter (S/cm) at 250C. Total Dissolved Solids (TDS) Gravimetric method is being used to determine TDS. A well-mixed sample was filtered through a standard glass fiber filter. The filtrate was evaporated and dried to constant weight using the evaporating porcelain dishes and oven model HI-9321 at 103-105°C. Alkalinity: A) Total Alkalinity is expressed in terms of the number of milligram equivalent of carbonate and bicarbonate and hydroxyl groups. B) Methyl orange was used as indication for total alkalinity determination. C) Titrate with sulfuric acid 0.1N or HCl 0.1N until flectional point appear. Hardness of water: The hardness is expressed in terms of the number of milligram equivalents of soluble Ca++ and Mg++ per liter of water. Anions analysis -- Sulfate (SO4 ): The sulfate was determined by spectrophotometer which detected the absorption at 540 nm [3]. Chloride (Cl-): The chloride was determined by (MOHR) method which used silver nitrate solution and potassium chromate as indicator [3]. - Nitrate (NO3 ): The nitrate was determine by spectrophotometer at 220 nm.The presence in the ground water or surface water is good indicator for water contamination which product by chemical activity [3]. - Bicarbonate (HCO3 ): The bicarbonate was determined by titration with diluted hydrochloric acid and methyl orange indicator [3] Cations analysis The concentration of calcium, potassium, magnesium, manganese and sodium determined using Flame Atomic Absorption Spectrophotometer (GBC Scientific Equipment SAVANTAA) according to condition shown in the Table (1)
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Heavy metals Analysis Samples were filtered using filtration system through 0.45 μm-pore-diameter filter paper then analyzed for ions using atomic absorption spectrophotometer (iCE 3000 Series AA Spectrometer– Thermo Scientific) Bacteriological Analysis of Groundwater Samples. Sterile 250 ml plastic bottle was taken for sample collection. Carefully unscrew the cap and immediately hold the bottle under the water surface of the wells and fill. Membrane filters (MF) method described by [8] was strictly followed; 100 mls of each water sample was filtered through sterile membrane which retained the bacteria on its surface. The membrane was removed aseptically and placed on a MacConkey medium that was then incubated at 37°C for 24 hr. Coliform colonies (indicating faecal contamination) growing on the surface of the membrane were counted and recorded as Coliform density (total Coliform colonies per 100 mL) or colony forming unit (CFU).
3. Results and Discussion
The data have been handled and interpreted in the following to understand groundwater salinization, general hydro geochemical evolution of groundwater. Table (2) In addition, the proportion of major ions in shallow groundwater is presented in Figure 2. From these two pie charts, it can be seen that Na+ and Cl- are the prevalent cation and anion. The relative abundance of the cations - is Na+ > Ca2+> Mg2+ > K+, and that of the anion is Cl-> SO42-> HCO3 for shallow-groundwater.
Total Dissolved Solid and Hydro Chemical Type of Groundwater: Total dissolved solid (TDS): Total Dissolved Solids (TDS) is a measure of the combined content of all inorganic and organic substances contained in a liquid in: molecular, ionized or micro-granular (colloidal solids) suspended form. The principal application of TDS is in the study of water quality, although TDS is not generally considered a primary pollutant it is used as an indication of aesthetic characteristics of drinking water and as an aggregate indicator of the presence of a broad array of chemical contaminants. According to TDS in water, groundwater is classified as fresh water (TDS<2.5g/L), slight saline water (2.5g/L
Spatial Variation of Groundwater Chemical Composition: Sample Groundwater:
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Taking into account the nearly “linear”” distribution of the sample wells in the direction of groundwater flow, the spatial variation of hydro-chemical characteristics then can be analyzed along the groundwater flow, namely the direction from inland to the sea. - + 2-- According to Figure 3 variations off concentrations of Cl , Na , So4 are in a good phase with that of TDS along the flow path. Generally, ion concentrations of groundwater in the south are much lower than that in the downstream of discharge region, and a dramatic fall occurs at the point of 70 km from the coast. TDS slumps from 7044 mg/L to 34991 mg/L and the concentration of Cl- fells down to 2943 mg/L from 834 mg/L at that point. Similarly but not sharply ions of Ca2+ and Concentra Mg2+ decrease from 662 mg/L to 331 mg/L and 332 mg/L to 152 mg/L respectively Figure 4. Additionally, several minor components such as Mn2+, Ba2+ and Si2+ fluctuated along the flow path with no obvious increase or decline Figure 5.
4. Bacteriological Contaminants
Groundwater also contains a broad spectrum of microbial types similar to those found in surface soils and waters. These microbes encompass bacteria, fungi and protozoa, and are representative of most physiological types. On occasion pathogenic viruses, bacteria and protozoans of gastrointestinal origin from domestic, agricultural and other anthropogenic activities, may infiltrate through soils, sediments and rocks to the underlying groundwater [10]. Faecal coliforms bacteria Maximum Acceptable Concentration for Drinking Water is none detectable per 100 mL [7, 15]. Coliform bacteria are present in the environment and feces of all warm-blooded animals and Humans [14].The faecal coliforms bacteria form per 100 ml from 10 well isolated from the studied groundwater samples of WadiJarif(Table 3) are ranged from 20 to 140 CFU/100 mL. The total count of coliforms bacteria Sources of Total and Fecal Coliform in groundwater can include: •Agricultural runoff drainage water, effluent from septic systems or sewage discharges and Infiltration of domestic or wild animal fecal matter [16]. The total counts of coliform per 100 mL isolated from 10 well samples of Wadijarif (Table3) are ranged from 40 to 2400 CFU/100 mL. Faecal Streptococci bacteria, the total estimate of the number of bacteria in the water gives a general idea of the degree of bacterial contamination of the water without reference to the types of bacteria in it[1].The faecal Streptococciform per 100 ml isolated from 10 well samples of WadiJarif are ranged from 20 to 500 CFU/100 mL., Table (3).
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5. Conclusions and Recommendations
Conclusions
Geology and hydrogeology of the Wadijarif have been characterized based on limited previous information and much current collected data. A hydrogeological concept of the groundwater system was established. Hydro geochemistry was employed to characterize the hydrochemical processes for water origin and evolution in groundwater systems.
1- Generally the quality of the underground water of the investigation zone not suitable as a drinking water before treatment (must be treated).
2- All pH values in the normal range.
3- The observed water quality changes (e.g. TDS and ions) from southern to northern part of the area with a remarkable rise at around 70 km and 55 km off the coast for sample well groundwater respectively.
4- These indicate mixing process with ancient salt water in shallow groundwater, whilst modern seawater intrusion more likely is induced in deep water apart from mixing with saline or brackish water in paleo-processes as indicated from geochemical evolution.
5- Artificial abstraction has also induced mixing of modern water and local old saline groundwater.
6- Among different bacteriological parameters measured in the studied groundwater of WadiJarif, the fecal coliform bacteria form from 10 wells isolated from the studied groundwater samples of WadiJarif are ranged from 20 to 140 CFU/100 mL. The total count of E. coli form ranged from 40 to 2400 CFU/100 mL. The Fecal Streptococci form per 100 mL ranged from 20 to 500 CFU/mL. which revealed that this groundwater is classified as unsafe.
Recommendations
1. Putting a permanent monitoring program to observe groundwater quality and determine the annual and seasonal changes in order to put a proper strategy to protect and remediate the aquifer especially that the groundwater is the lonely water resource in WadiJarif area.
2. Control actions of private water well drilling companies by the related authority to limitation the random and unscientific wells drilling.
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3. Conclusions about seawater intrusion will be much more reliable if a comprehensive isotopic analysis should be carried out with support of other trace elements such as Br and I to be introduced as markers for the seawater intrusion.
4. Design and construction of monitoring wells must be planned for better control of seawater intrusion.
5. Groundwater contamination from organics and heavy metals is not my scope in this study but this is an important area for future work in this part of Libya. References
1. Abawi, S. A. and Hassan, M.S. (1990): The environmental scientific. Water test, Dar Al-hekma for typing & publishing. Al-Mosel– Iraq. 2. Abdul Jameel, A., Sirajudeen J. and Abdul vahith R. (2012): Studies on heavy metal pollution of ground water sources between Tamilnadu and Pondicherry, India. Adv. Appl. Sci. Res., 3 (1): pp.424- 429. 3. American Public Health Association, (1992): Standard Methods for the Examination of Water and Wastewater, 21st ed. American Public Health Association, Washington, D.C. 4. American Public Health Association, (1999): Standard methods for the examination of water and wastewater. 21thEdn.American Public Health Association, Washington, D.C. 5. Brown.L.R and Root, (1990): Agricultural strategies report, sirt small farms. 6. Edmunds, W.M. (2003): Hydrogeochemical processes in arid and semi-arid regions - focus on North Africa. In: Simmers, I. Understanding water in a dry environment "Hydrological processes in arid and Semi-arid Zones" Swets&Zeitlinger B.V., Lisse, The Netherlands, pp.251-289. 7. Edmunds, W.M. (2003): Hydrogeochemical processes in arid and semi-arid regions - focus on North Africa. In: Simmers, I. Understanding water in a dry environment "Hydrological processes in arid and Semi-arid Zones" Swets&Zeitlinger B.V., Lisse, The Netherlands, pp.251-289. 8. Elango, L. and Kannan, R. (2007): Rock–water interaction and its control on chemical composition of groundwater. In: Sarkar, D. Datta, R. and Hannigan R. (Eds.) Developments in Environmental Science. Elsevier, pp.229-243. 9. El-Ghawi, U.M. (2005): The level of trace elements in Tripoli City groundwater. Instrum. Sci. and Tech., 33: pp.609-617. 10. Elgzeli, Y.M. (2010): Future groundwater development in the Jifarah Plain, Libya, and possible environmental impacts: regional approach. Ph.D Thesis, Fac. Sci., Charles Univ. Prague, 71 P. 11. Kumar, A., Zaiad, G.M., Awheda, I.M. and Fartas, F.M. (2014): Physico-Chemical analysis of ground water in different sites of Al-khums City, Libya. Inter. J.Sci. Res. (IJSR), 3 (7): pp.2395- 2398. 12. Manimaran, D. (2012): Groundwater geochemistry study using GIS in and around Vallanadu Hills, Tamilnadu, India. Res. J. Recent Sci., 1 (7): pp.52-58. 13. Ministry of Health (1999): “Safe Water Supply Vital to Your Health.”(1999)http://www.healthservices.gov.bc.ca/protect/pdf/PHI052.pdf 14. Mohamed, F.E. (2014): Population growth and water consumption in Libya (Reality and future prospects). Inter. J. planning, urban and sustainable develop. 1 (2): pp.22-30. (In Arabic).
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15. Mumtazuddin, S., Azad, A.K., Firdaus, R. and Kumari, A.(2013): Water Quality Evaluation in Some Groundwater Samples along the BudhiGandak Belt of Kanti Block in Muzaffarpur District during Post-Monsoon Season, 2012. J. Chem. Biol. Phys. Sci., 3 (1): pp.605-611. 16. Noble, R.T.; Leecaster, M. K.; McGee, C. D.; Weisberg, S.B. and Ritter, K. (2003): “Comparison of Total Feacal Coliform and Enterococcus Response for Ocean Recreational Water Quality Testing,” Water Research, 37, No. 7, pp. 1637-1643. 17. Parihar, S.S., Kumar, A., Gupta, R.N, Pathak, M., Shrivastav, A. and Pandey, A.C. (2012):Physico- Chemical and Microbiological Analysis of Underground Water in and Around Gwalior City, MP, India. Res. J. Recent Sci., 1 (6): pp.62-65. 18. Plazinska, A. (2000): Microbiological quality of drinking water in four communities in the AnanguPitjantjatjara Lands, SA. Bureau of Rural Sciences, Canberra. 19. Sen, Z. (2008):Wadi Hydrology. New York: CRC:pp13-14 20. Tmava, A., Avdullahi, S. and Fejza, I. (2013): Assessment of heavy metal study on groundwater in the mining area in Stan Terg, Kosovo. J. Biodiv. Environ. Sci., 3 (2): pp.53-60. 21. Todd, D.K. (1963) : Groundwater hydrology. Second edition. John Wiley & sons, New York, pp 535 22. Viena and Austria, (2006). Nubian Sandstone Aquifer System (NSAS) Technical Baseline Meeting. 23. WHO, (1993): Guidelines for drinking water quality. (2nd ed.)1 - Recommendations, Geneva, ISBN 92 4 154460. 24. WHO, (2005): Nutrients in Drinking Water Protection of the Human Environment Water, Sanitation and Health. Geneva, Switzerland. 25. WHO, (2006): Protecting Groundwater for Health: Managing the Quality of Drinking-water Sources. Edited by O. Schmoll, G. Howard, J. Chilton and I. Chorus. ISBN: 1843390795. Published by IWA Publishing, London, UK.
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Figure 1. Location map of Sirte showing WadiJarif.
Figure 2. Proportions of Major Ions as mg/L in Groundwater
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2_ Figure 3. Variation of TDS, Cl-, Na+ and SO4 with Distance from the Sea
Figure 4. Variation of Ca2+ and M g2+ with Distance from the Sea
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Figure 5. Variation of Ba2+, Mn2+ and, Si2+ with Distance from the Sea
Table 1. Conditions of Flame atomic absorption spectrophotometer.
Wave length Slit Element Fuel Oxidant Measurement (nm) width(nm)
Ca 422.7 0.5 C2H2 Air Absorbance
K 766.5 0.2 C2H2 Air Emission
Mg 285.2 0.5 C2H2 Air Absorbance
Na 589.0 0.2 C2H2 Air Emission
Table 2. Summary of groundwater hydrochemistry in WadiJarif_sirt
Shallow groundwater
Maximum Minimum Average
Ph 7.69 7.05 7.23
TDS(mg/l) 8368.52 3209.49 5578.33
Hardness (mg CaCO3/l) 3017.58 1300.41 2162.53
Na+(mg/l) 1760.00 507.50 1154.23
K+(mg/l) 72.00 53.00 63.53
Ca2+(mg/l) 670.20 320.08 501.03
Mg+2(mg/l) 331.95 115.25 218.39
- HCO3 (mg/l) 331.95 214.70 244.42
Cl- 2975.00 823.40 1802.06
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Table 3. The total count of coliforms bacteria, Faecal coliforms and Faecal Streptococci isolated from the studied groundwater samples of WadiJarif.
MPN/100ml Well Name Total Faecal Faecal Coliform Coliform Streptococci
Sample No. Sample
1 Ahmed 300 140 1> 2 Alkazan 110 80 80 3 Alfergania1 1> 1> 20 4 Alfergania2 40 1> 1> 5 Alnakos 170 1> 20 6 Almohageren 1> 1> 40 7 Alachren 1> 1> 130 8 Amgahed 1> 1> 80 9 Moaskarsetean 130 1> 130 10 Alsoada 2400 20 500 WHO limit <1 <1 <1
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.F.M.Shembesh , M. E. Buzgheia, F. M. Kutrani , N.F.BenJeweref, N. M. Elbagermi, S. A. Salem
Sirte University Scientific Journal (Applied Sciences) Vol.10 (1), Jun.2020
The Role of Ultrasound in The Diagnoses of Graves’ Disease Faisal M.Shembesh , Mohamed E. Buzgheia, Faiza M. Kutrani , NadyaF.BenJeweref, Nadeia M. Elbagermi, Seham A. Salem.
Department of Radiology, faculty of medicine, University of Benghazi
Abstract
Aim: To explore the use of ultrasonography and Doppler as an indispensable diagnostic modality in the evaluation and the diagnosis of Graves’ disease. Methods: in this prospective study we examined 30 cases of gravis disease and 20 normal controls using the B- Mode sonographic criteria (thyroid size and echogenicity) and Doppler criteria (color flow mapping and spectral analysis the peak systolic velocity in the thyroidal arteries and the resistive index within the thyroid parenchymal vasculature). Results: when using more than one sonographic and Doppler criteria, thyroid size, echogenicity, Color flow mapping (qualitative) and spectral Doppler values as peak systolic velocity (PSV) in thyroidal arteries and thyroid parenchyma RI. As a test for diagnosis of Grave's disease. Most patients with Graves’ disease showed increased thyroid volume, heterogeneous parenchyma, marked increased parenchymal vascularity and significantly increased PSV in thyroidal arteries. Conclusion: Ultrasonography Doppler is a cost-effective, noninvasive, portable, and safe imaging modality in the evaluation of Graves’ disease,
Keywords: Thyroid, Graves’ Disease, Ultrasonography, Color-Flow Doppler
1. Introduction
Graves’ disease (GD), as known today, is an autoimmune, diffuse, chronic disease of thyroid gland, as described by Robert Graves in 1835 [1].
Graves’ disease is the most common cause of hyperthyroidism, which has an estimated prevalence in iodine sufficient areas of 20/1000 females and 2.3/1000 males [2]. It is most common in females between the ages of 20 and 50 years, but it may occur at any age. The laboratory diagnosis of Graves’ disease is based on the finding of high serum thyroid hormone and undetectable serum TSH concentrations associated with circulating thyroglobulin and thyroperoxidase antibodies. TRAb is detectable in almost 90% of patients, but usually it is not needed for the diagnosis.
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After the introduction of the ultrasound into clinical practice in the late sixties, thyroid ultrasonography (US) proved to be very effective in the diagnostic approach to thyroid diseases, the anatomical location of the gland being advantageous for this technique. The most widely used application of thyroid US is identification and characterization of thyroid nodules [2]. Rapid improvements in the development of US equipment have made available real-time high frequency transducers (7.5–10 MHz) with high resolution, which allow a more precise definition of the echostructure of the thyroid tissue.
In B-mode ultrasound, the normal thyroid has a peculiar echogenicity, making the gland well distinguishable from surrounding neck structures. Thyroid echogenicity is due to the gland’s follicular structure the interface between thyroid cell and colloid exhibits high acoustic impedance, causing high frequency acoustic waves to be reflected back to the probe leading to the characteristic ground glass appearance of normal thyroid (fig. 1).
Figure1. Normal B-mode ultrasound appearance of thyroid with ground glass appearance (b) compared the enlarged heterogamous thyroid of Graves’ disease (b)
Conditions that change the normal anatomical structure of the gland as Graves’ disease cause this echo pattern to be altered (fig1). In addition, recently developed color Doppler technology allows determination of the blood flow through the gland, offering the possibility of qualitative parenchymal vascularity assessment with color flow mapping and spectral quantitative measurements, such as the peak systolic velocity of the blood flow at the level of thyroid arterial vessels (i.e. inferior thyroid artery) and thyroid parenchymal flow resistive index (R.I). Using these techniques, thyroid blood flow has been shown to be correlated with the thyroid status in patients with Graves’ disease.
In this scenario, thyroid color-flow Doppler ultrasonography (US Doppler) presents a widely available, low cost, non-invasive and radiation free method, providing initial diagnosis and follow up of patients with GD. In addition, this method is used in differential diagnosis with other causes of thyrotoxicosis in the early stage.
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.F.M.Shembesh , M. E. Buzgheia, F. M. Kutrani , N.F.BenJeweref, N. M. Elbagermi, S. A. Salem
2. Patient and method
30 cases with Graves' disease (3 male and 27 female) The Inclusion criteria of the cases depend on the clinical and laboratory investigation presenting in the endocrine clinics with thyrotoxicosis , Exclusion criteria included toxic nodules, multinodular goiter, history of thyroid surgery, radioiodine therapy or radiation exposure to neck. The study done in the Benghazi from 4 April 2018 to 1-January-2019. 20 adults were randomly selected as control group from patient were referred for other neck ultrasound and Doppler examinations. The inclusion criteria were absence of history of any thyroid related disease. Sonographic and Doppler examination was performed at Al Hawari general hospital department of Radiology and Benghazi medical center department of radiology using a Hitachi and Phillips sonographic machines with a 7.5-MHz transducer supported with Color and spectral Doppler.
B Mode Evaluation We evaluated the GD cases and the controls, with the B mode sonography, the gland dimension (volume) and thyroid parenchyma alterations. Although, focal lesions occurrence (nodules) is unusual in GD, whenever they are found, they should be evaluated according to their features by B mode and color Doppler
Estimation of thyroid volume The thyroid gland correct volume should be obtained by maximum measures in the longitudinal (L), anteroposterior gland volume (AP) and transverse (T) axis of both lobes and isthmus (Figure 2). The volume (TV) the ellipse correction coefficient used is (TV = L × AP × T ×π/6) (Figure 2). The lobes and isthmus volumes are added to obtain the total thyroid volume.
The normal adult thyroid volume values 13 ± 5ml [2], with no gender distinction in the given population. According to that we divided the thyroid size into normal 10±5ml, mildly enlarged 20±5ml, and markedly enlarged 30±5ml.
Figure 2.Scheme demonstrating how thyroid lobes should be measured in the longitudinal and transverse axis
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Thyroid gland echogenicity Normal gland has an echogenicity characteristic in ultrasound as described, easily distinguishable from different diffuse thyroid pathology by the reduction or increase in its echogenicity, micro- nodularity, nodular lymphocytic infiltration diffuse or patchy (Swiss cheese), fibrous bands. These B-Mode ultrasound features were evaluated in all of our cases of GD. And normal controls,
3. Color and Spectral Doppler Ultrasonography
Color flow mapping Qualitative Assessment of thyroid vascularity with Color Flow Doppler Mapping (CFM) using the following criteria:
Pattern 0 : minimal intraparenchymal blood flow Pattern I: presence of mild parenchymal blood flow with patchy uneven distribution (fig 3). Pattern II: moderate increase of color flow Doppler signal (fig 4). Pattern III: markedly increased color flow Doppler signal with diffuse homogeneous distribution, the so-called “thyroid inferno" (fig 5)
Figure 5 Figure 4 Figure 3
Spectral analysis Peak systolic velocity: Thyroid arteries peak systolic velocity (PSV) measurement is done with sample volume 1-2 mm adjustment, in vessel center, the insonation angle should be 0˚- 60˚ and correction angle adjusted parallel to the vessel wall (Figure 6). The PSV can be measured in the inferior or the superior thyroid arteries. There is no significant difference between the PSV in the inferior thyroid artery gland of both sides.
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.F.M.Shembesh , M. E. Buzgheia, F. M. Kutrani , N.F.BenJeweref, N. M. Elbagermi, S. A. Salem
Figure 6. Duplex-colour Doppler of the superior thyroid artery with the probe positioned in the oblique sagittal Flow Parameter Measured the Peak Systolic Velocity (PSV) and (RI).
Thyroid parenchymal Flow Resistive Index RI: The arterial flow resistive index RI. is reflecting the intraparenchymal flow resistance in the thyroid, we estimated RI. Either in the thyroidal arteries or in the intraparenchymal thyroid arterioles with the smallest sample volume 1-2mm. it was calculated using the software built in the used ultrasound equipment.
4. Results
Fifty subjects were included in this study. Thirty (60%) subjects were diagnosed with Grave's disease by clinical examination and laboratory tests, while 20 (40%) were not having the disease. Thirty four of the subjects were females (68%), and 16 (32%) subjects were males. The mean age of all the subjects was 39.40 years. With SD 13 years, there was no significant (P> 0.05) differences between the patients and the normal subjects regarding their mean ages (37.73 years, 41.90 years respectively). After performing ultrasonography and Doppler study of thyroid gland for all the subjects, 93.3% of the GD. patients showed enlarged thyroid gland size, and all normal subjects had a normal gland size. Increased vascularity was obvious among the vast majority of the GD. patients 96.7%, while it was recognized among only 10% of the normal subjects. Heterogeneous echo-pattern was seen only among 56.7% of the GD. patients. High PSV were seen among 83.3% of GD. Cases and high RI 23.3% of the patients respectively figure 7.
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100 93.3% 96.7% P<0.05 90 83.3% % 80 70 60 56.7% Normal 50 subjects 40 30 23.3% 20 10% 10% Patients with 10 0% 0 0% Grave's disease 0
Figure 7. Distribution of the subjects according to the result of ultasonography and Doppler study of thyroid gland.
- The size is significantly higher in patients with Graves’ disease than in normal subjects (X2= 42.42 , P = 0.000). The sensitivity of increased size only as a test for diagnosis of Grave's disease is 93.33 % (95% CI 77.93%- 99.18%), its specificity is 100% (95% CI 83.16%- 100%)
- Heterogeneity is significantly (P=0.000) more among subjects with Graves's disease (table 2). The sensitivity of the heterogeneity as a test for diagnosis of Grave's disease is 56.67% (95% CI 37.43%- 74.54%), its specificity is 100% (95% - CI 83.16%- 100 %), figures 8&9.
- PSV is significantly higher in patients with Graves’ disease than in normal subjects (X2= 25.98, P = 0.000). The sensitivity of increased PSV only as a test for diagnosis of Grave's disease is 83.33 % (95% CI 65.28%- 94.36%), its specificity is 90% (95% CI 68.30%- 98.77%)
- Vascularity grade III is significantly (P=0.000) more among subjects with Graves's disease (table1). The sensitivity of increased vascularity as a test for diagnosis of Grave's disease is 96.67 % (95% CI 82.78%- 99.92%), its specificity is 90% (95% - CI 68.30%- 98.77%), figures 8&9.
- RI is significantly higher in patients with Graves’ disease than in normal subjects (X2= 5.42, P = 0.02). The sensitivity of increased RI only as a test for diagnosis of Grave's disease is only 23.33%.
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RI 23.33%
Heterogeneity 56.67%
PSV 83.33%
Incresed size 93.33%
Increased vascularity 96.67%
0 50 100
Figure 8. Distribution of the criteria according to the level of their sensitivity in diagnosis of Grave's disease
PSV 90%
Increased vascularity 90%
Heterogeneity 100%
Incresed size 100%
RI 100%
0 20 40 60 80 100
Figure 9. Distribution of the criteria according to the level of their specificity in diagnosis of Grave's disease. .
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Table 1 shows that the vascularity grade III is significantly (P=0.000) more among subjects with Graves's disease.
Table 1 .Distribution of the study subjects according to clinical &lab. Diagnosis and vascularity grading.
2 Type of Grave's disease Total X P-Value echopattern No Yes Homogenous 02 (100%) 13 (43.3%) 33(66%) 17.172 0.000 Micro nodular 2 (2%) 8(26.7%) 8 (16%) ecopattern Heterogeneous 2 (0%) 9 (30%) 9 (18%) Total 20 (100%) 30 (100%) 50 (100%)
Table 2 shows that the heterogeneous and micro nodular echo pattern is significantly (P=0.000) more among subjects with Graves's disease.
Table 2.Distribution of the study subjects according to clinical &lab. Diagnosis and the ecopattern type.
Vascularity Grave's disease Total X2 P-Value grade No Yes
I 5 (25%) 1 (3.3%) 6 (12%) 26.06 0.000 II 13 (65%) 4 (13.3%) 17 (34%) III 0 (10%) 25 (83.3%) 26 (54%) Total 20(100%) 30 (100%) 50 (100%)
5. Discussion
In our study B mode ultrasound evaluation. Thyroid gland dimension (volume) and diffuse thyroid parenchymal alterations representing the two major sonographic diagnostic features in GD. If compared to the normal thyroid with high sensitivity and specificity, on the other hand these two features loss this advantage if compared to the other thyroid autoimmune disease as Hashimotos thyroiditis. As in both pathological entities thyroid gland is enlarged with diffuse parenchymal heterogenecity. In Graves’disease, there is a diffuse increase of thyroid parenchymal vascularization, known as “thyroid inferno” (Figure 5), a term first used to describe this phenomenon by Ralls et al. publication, in 1988[5]. Thyroid hypervascularization can also occur in thyroiditis, but at a lesser level
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.F.M.Shembesh , M. E. Buzgheia, F. M. Kutrani , N.F.BenJeweref, N. M. Elbagermi, S. A. Salem
[5]. In our study more than 96% of GD. Thyroid Showed hypervascularity adding a major sonographic color Doppler feature in the diagnosis of GD. That also differentiate thyroid of GD. Not only from normal thyroid but also from other autoimmune thyroiditis. The quantitative Doppler evaluation, the peak systolic velocity (PSV) in the inferior thyroidal artery (ITA) or superior thyroidal artery (STA). The normal PSV values obtained was 24.80 cm/s and 25.85 cm/s in the superior thyroid arteries and 20.92 cm/s and 21.50 cm/s in the inferior thyroid arteries [7]. In our study, the mean PSV in the thyroid arteries in GD thyroid was 73.8 cm/s. Compared to 23.5 cm/s. in normal thyroid In our experience, a cut off 50.0 cm/s velocity is considered to GD diagnosis measurement in the inferior thyroid arteries , The sensitivity of increased PSV only as a test for diagnosis of Grave's disease is 83.33 % and its specificity is 90%. Donkol et al. [6] considered the systolic peak velocity 40.0 cm/s in the inferior thyroid artery and higher is suggestive of GD, Therefore, the high PSV in GD. correlates with increased cardiac output due to hyperdynamic status secondary to thyrotoxicosis. There is significant increases in systolic BP (blood pressure), PR (pulse rate) and CCV (common carotid artery velocity) on both sides in GD. patients. Finally the quantitative Doppler value R.I. which represents the change in thyroid tissue peripheral vascular resistance, in our study it was showing a limited value in differentiation thyroid of GD. From the normal thyroid, as it was showing an increased RI. In 23% of cases of GD.
6. Conclusion
Thyroid gland imaging assessment in GD should be multifactorial, considering B-mode, color Doppler and spectral Doppler features these will increase the diagnostic accuracy of GD. The ultrasound and Doppler diagnostic criteria is the glandular volume increase, heterogeneity and parenchyma hypoechogenicity, diffuse increase in parenchymal vascularity and thyroid arteries increase peak systolic velocity
The B-Mode ultrasound and Doppler are very important for diagnosis of GD and follow up in order to assist the physician during therapy.
Thus, US Doppler is an excellent alternative to radioisotopes exams, with similar accuracy and without contraindication
References
[1] Graves, R.J. (1835) Newly Observed Affection of the Thyroid. London Medical and Surgical Journal, 7, 515. [2] Hegedus L &Karstrup S. Ultrasonography in the evaluation ofcold thyroid nodules. European Journal of Endocrinology 1998 138, 30–31.
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[3] Macedo, T.A.A. (2006) Distinção entre osTipos 1 e 2 de TireotoxicoseAssociada à AmiodaronaporMeio de Dúplex-Doppler Colorido. Doutorado, Universidade de São Paulo, São Paulo. [4] Vanderpump MP, Tunbridge WM, French JM, Appleton D,Bates D, Clark F et al. The incidence of thyroid disorders in the community: a twenty-year follow-up of the Whickham Survey. Clinical Endocrinology 1995 43 55–68 [5] Ralls, P.W., Mayekawa, D.S., Lee, K.P., Colletti, P.M., Radin, D.R., Bosnell, W.D., et al. (1988) Color- Flow Doppler Sonography in Graves’ Disease: “Thyroid Inferno”. American Journal of Roentgenology, 150, 781- 784.http://dx.doi.org/10.2214/ajr.150.4.781 [6] Donkol, R.H., Nada, A.M. and Boughattas, S. (2013) Role of Color Doppler in Differentiation of Graves’ Disease and Thyroiditis in Thyrotoxicosis. World Journal of Radiology, 5, 178-183. [7] Kim TK, Lee EJ. The value of the mean peak systolic velocity of the superior thyroidal artery in the differential diagnosis of thyrotoxicosis.Ultrasonography. 2015 Oct;34 (4):292-296
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Mona. M. Al gobbi
Sirte University Scientific Journal (Applied Sciences) Vol.10 (1), June 2020
Unilateral Dermoid Ovarian Cyst In Nulliparous Women
Mona Mohammed Al gobbi Mona. [email protected]
Obstetrics and Gynecology Department, Faculty of Medicine, Sirte University, Libya
Abstract
Ovarian dermoid cyst are the most common germs cell tumors of ovarian and make up about two thirds of all ovarian tumors. They occur mostly in women between the second and fourth decades of the life and usually present with non-specific symptoms including lateral onset menarche and menstrual cycle abnormalities.
It is reported the case of 23 years old women, who presented with sudden onset of severe lower abdominal pain and nausea, similar episode of pain were experienced in the previous few months and diagnosed as a case of unilateral ovarian cyst. She was found to have unilateral – ovarian torsion caused by adnexal mass. She was managed by detorsion and Rt. Cystectomy and Laparotomy at Ibn- Sina Teaching Hospital.
Mature teratoma is an important gynecological morbidity whose prompt diagnosis and management can ever serious complication. We therefore preset this case to raise physician awareness on common presentation of common gynecological tumor.
Keywords: Unilateral dermoid cysts, cystic teratoma, detorsion cystectomy and laparotomy
1. Background
Ovarian dermoid cyst or mature teratoma are germ cell tumor composed of well differentiated derivatives of 3 germ layer's ectoderm, mesoderm, and endoderm [1]. There are the most common germ cell tumour of the ovaries and make up to 20 to 30% of all ovarian tumors [2]. Of all patients undergoing emergency surgery for acute pelvic pain, approximately 2.7% of cases are caused by ovarian torsion [3]. It is defined as the partial or complete rotation of adnexa around its vascular 47 Vol.10 (1),74-80,June.2020
Unilateral Dermoid Ovarian Cyst …... axis that may cause and interruption in the ovarian blood and lymphatic flow [4]. It is reported to occur at any age from pre-puberty to post menopause with the greatest incidence in women 20 – 30 years of age [5]. The most common benign tumor reported to have ovarian torsion is dermoid and its diagnosis is based on the clinical presentation. If ovarian torsion is suspected, then an emergency surgical intervention should be performed to prevent ovarian damaged. We report a case of unilateral ovarian torsion treated bt. Laparotomy, ovarian detorsion and cystectomy.
2. Case Report
It is reported the case of 23 years old Nulliparous female Libyan, presented to our institution with history of sudden onset of sever lower abdominal pain and nausea. The pain described as constant sharp radiated to her back and associated with episode of vomiting after few hours , similar episode of pain were experienced I the previous few months and diagnosed as a case of unilateral dermoid in another hospital but case not documented .
This episodes of pain were, however shorter in duration and there were no other associated gastrointestinal or gastro urinary symptoms. Bedside demonstrating unilateral cystic mass on the Right side around 10x 9 cm with negative Doppler flow She had no previous history of any illness or allergies. An ultrasound examination was performed in the ovarian tissue with evidence of solid components.
On the basis of these findings, ovarian torsion caused by adnexal mass was the likely diagnosis. A presumptive diagnosis of unilateral ovarian torsion was made and she was consulted on the need for an emergency Exploratory Laparotomy, decision to incision time was about 30 minutes, Intra operative findings confirmed unilateral ovarian torsion that was the same size as that found by ultrasound.
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Mona. M. Al gobbi
There was no ascites, Right ovary were enlarged approximately as estimated by ultra sound scan. The Right ovary had twisted on their infundibula pelvic ligaments, slightly edematous with intact capsule and locked viable, there was no evidence of hemorrhage or adhesion. The uterus, bilateral fallopian tubes and remainder intra peritoneal contents appeared to be normal. The ovaries were untwisted and unilateral cystectomy (i.e. Right) was done. There were no intra operative complication, she was managed with intravenous fluid and antibiotics. She made an unremarkable, the pain resolved completely after surgical and final pathologic diagnosis was unilateral mature ovarian teratoma (dermoid). She was discharged on the 3rd post-operative day and advised to follow up after 4th week. She recovered completely from her surgery and has gone back to her normal life.
3. Discussion
Mature cystic ovarian teratoma are benign ovarian tumor , accounting for about 95% of all ovarian teratoma , and about 10 to 20% of all ovarian tumor [6]. It can happen in all age groups however it is the most common ovarian tumor encountered in women in their 20's and 30's [7] .It is through to airs from the germ cell of the ovary and it is composed of cystic material and organized structures. All the three cell layers can be found in it, microscopically it often contains many cystic area with teeth, hair or hairs mixed with sebaceous, sticky and foul smelling material. Commonly mature cystic teratomas of the ovary are unilateral except in about 8-15% of cases were found to be bilateral [8, 9]. The most common complication is torsion; whereas rupture and suppuration is common complication. [10] In the present case, acute sharp and constant pelvic pain was the presenting symptoms of the unilateral dermoid cyst torsion were diagnosed. The most common symptoms of ovarian torsion is
47 Vol.10 (1),74-80,June.2020
Unilateral Dermoid Ovarian Cyst …... acute onset of lower abdominal pain, followed by nausea and vomiting.[11].The ovarian enlargement is one of the risk factor for the torsion , in 80 % of ovarian torsion , the ovaries measure more than 5 cm. [12]. The most common benign tumor reported to have ovarian torsion is mature ovarian teratoma (dermoid cyst). Imaging studies, including high resolution real time, two dimensional Ultra sonography and computer tomography are helpful in the differential diagnosis of dermoid cyst, but are not so useful in showing the site of torsion of the ovarian cyst, Color flow Doppler mapping may be helpful in localizing the tumor torsion. [13]. In the present case, the diagnosis was confirmed by a bedside ultrasound examination which demonstrated unilateral ovarian cyst mass, accompanied by negative Doppler flow in the ovarian tissue with the evidence of solid components.
The diagnosis of ovarian torsion depends on a detailed history, examination and imaging. Pelvic ultrasound which is the initial imaging of choice will show enlarge ovarian mass with either an absent in Doppler flow or reduce flow in the vessel due to torsion of the ovary. [14-15].
The diagnosis of torsion in this case was not challenge because of the classical history of sudden of lower abdominal pain and examination finding of tender lower abdomen with palpable mass, the diagnosis was later confirmed with ultrasound finding of unilateral adenexa mass with no flow on Doppler interrogation, Management of torsion of the ovary is surgical either through Laparoscopy or through laparotomy [16]. In this case, was prompt managed with laparotomy and cystectomy other detorsion of ovaries the reason of the above management was chosen because patient was young. Nulliparous woman and desired fertility and no sign of malignancy. The main benefit of our management was the ability to be able grossly determine the viability of the ovary after detorsion were emphasize that early surgical intervention should be considered. In case of large cyst to prevent complication such as torsion which occurred in our case.
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4. Conclusions
Our case of unilateral ovarian torsion in nulliparous woman who was seen earlier in our outpatient department with unilateral ovarian mass only for her to come as an emergency and it's show the need for early surgical intervention in a nulliparous women with confirmed of big unilateral ovarian mass, so as to prevent emergencies like torsion and when these emergencies do occur prompt diagnosis and surgical intervention should be done and surgical intervention should be done to salvage the ovaries.
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Unilateral Dermoid Ovarian Cyst …...
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Mona. M. Al gobbi
References
[1] Sah, S. (2004) “Germ cell tumors of the ovary: A clinic pathological study of 121 cases, Nepal Journal of Obstetrics and Gynecology, No. 30, V4, pp 303-308 [2] Inkdlu, S. (2015) “An usual age presentation of mature cystic teratomas : A case report, International Journal of Reproductive and contraceptives, Obstetrics and Gynecology, No. 4, V4, pp 1234-1236. [3] McWilliams, G. D, and Hill D. (2008) Gynecologic emergencies Surgery Clinics , North Am, No. 88, pp 265-83. [4] White, S J. (2005) Ovarian Torsion: 10 year perspective. Emergency Med. Australas, No.17, 231-237. [5] Bazot, M., and Cortez, S (1999) Imaging of dermoid cyst with foci of immature tissue, Comput Assist Tomogr, No.23, pp 703-706. [6] Ayan, A., and Bulkumez, O. G (2000) Mature Cystic Teratoma of the ovary case series from one institution ovaryb34 years, Eur j obstet gynecol reprot Biol, No. 88, p153. [7] Lakkis, W. M, and Gelfand, M. M (1985) Benign cystic teratoma of the ovary: a 6year review. Can J surg, No. 28, PP 444-446. [8] Pepe, F., and Panella, M. Pepe,G., Panella, P. and Pennisi, F. (1986) the presence of a unilateral mature cyst teratoma, man_- Dermoid cysts of the ovary. Eur J. Gynaecol Oncol, No. 7, pp186-191 [9] Outwater, E. K., Siegelman, E. S.,and Hunt, J.L (2001) Ovarian Teratomas Tumor types and Imaging Characteristics Radio Graphics, No. 21, p 47590. [10] Comerci, J. T., Jr Licciardi, F., Benign, P. A (1994) Mature Cystic Teratoma a Clinicopathologic Evaluation of 517 cases and review of the Literature , Obstet Gynecol, No. 84, pp 8-22. [11] Houry, D., and Abbott, J. T (2001) Ovarian Torsion: A fifteen year review, Ann Emerg Med, No. 38 pp 156-159. [12] Ci, H, and Mun-Kun, H., and Dah-Ching, D (2017) A review of ovarian torsion, Tzu Med Journal, No. 29, V 3, pp143-147. [13] Pascual, M. A, and Tresserra, F., and Lopez –Marin, L., and Ubeda A., Grases, P. J., Dexeus, S. (2000) Role of Color Doppler Ultrasonography in the Diagnosis of Endometrioitc Cyst J. Ultrasound Med. No. 19, pp 695-699. [14] Wilkinson, C., and Sanderson, A (2001) Adxenal torsion a multimodality imaging review, Clain Radiol, No. 67, pp 476-483 [15] Lee, E. J., Kwon, H. C., Joo, H. J., Suh, J. H., Fliesche, R. A. C (1998) Diagnosis of Ovarian torsion with the color Doppler Sonography: Depiction of twisted vascular pedicle J. Ultrasound Med, No. 17, pp 83-89. [16] Tsafrir, Z., Hasson, J., Levin, I., Solomon, E., Lessing, J. B (2012) Adnexal torsion: Cystectomy and ovarian fixation are equally important in preventing recurrence. Eur Journal of Obstet Gynecol Reprod Biol, No. 162, pp 203-205.
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Removal of Multi Heavy Metals in One Batch System …...
Sirte University Scientific Journal (Applied Sciences) Vol.10 (1), June 2020
Removal of Multi Heavy Metals in One Batch System onto Surface of Activated Palm Kernel
Ragwan Mohamed1 and Alaa Mustafa2 [email protected]
1Department of Chemistry, Sirte University, Libya 2Department of Environmental Science, Alexandria University, Egypt
Abstract
This paper investigating the ability of palm kernel as a natural adsorbent for the removal of multi heavy metals from polluted real sample. Batch method of extraction was applied to determine the physic-chemical properties of adsorbent material. Results showed maximum removal of 70.5% (pH 3), 80.5% (pH 5) 73.5% (pH 9) for Cr (IV), Cu(II) and Pb(II) metal ions, respectively. The method was applied for the removal of the studied metal ions from a real water sample, and the recovery was recorded in the order Pb(II) > Cu(II) > Cr(VI). These findings conformed the potential ability of palm kernel as a good adsorbent for the removal of Cr (VI), Cu (II) and Pb(II) from real sample.
Keywords: Batch method of extraction, palm kernel, Removal of heavy metals.
1. Introduction
Over the past several decades, the population and social civilization expansion has over changed and affected life styles. The continuing progress of industries with the rising awareness of their activities has intensified numerous deteriorations on several ecosystems and seriously threatens the human health and environment [1]. The introduce of industrial materials by man into environment causes hazards to human health, harm to living resources and ecological systems, damage to structures or amenity, or interference with legitimate uses of the environment. Water is essential for life used for various purposes in community life such as cooking, drinking, washing, watering gardens, etc. However, the demand of water is developed with population has increased. In addition, a huge amount of water is required to run industries. The contamination of water with the rapid industrialization has been taking place which reduces its usefulness to humans and other organisms in nature. The most commonly water pollution is associated with the discharge 18 Vol.10 (1),81-86,June.2020
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of effluents from sewers or sewage treatment plants, drains and factories. The control and prevention of water pollution have been wide spread attention in the recent years by researchers, agencies and governments due to the toxicological importance in the ecosystem, agriculture and human health [2]. Many strategies have been developed especially for treating heavy metal wastewater such as chemical precipitation, the ferrite method, oxidation, ion exchange, adsorption, membrane separation, the electrochemical method and the electro-dialysis method [1,3]. Adsorption is one of the alternative treatment processes used [4]. Recently, much attention has been paid to investigate the cost efficient sorbents using in real designing experiments by materials locally available in large quantities such as natural materials, clays, agricultural waste or industrial byproducts [5]. The present study is focused on removal of chromium (VI), copper (II) and lead (II) on the low-cost abundant adsorbent such as palm kernel.
2. Materials and Methods
2.1 Instrumentation and Reagents 2.1.1 Instrumentations Lab-Line reciprocating water bath shaker (15-250 cycles per minute, Temperature controller up to 65°C), pH meter OAKTON 510 Series, flask shaker (Stuart), and Thermo AA spectrometer/M series supplied with GF95- graphite furnace with auto sampler, Iso-temp Oven (fisher scientific, Model 255G) were used in this study. 2.1.2 Chemical Reagents K2Cr2O7, CuSO4 and Pb(NO3)2 were obtained from Fisher Scientific, hydrochloric acid (HCl), Honeywell, trace metal grade, sodium hydroxide (NaOH), Fisher Scientific, analytical grade, nitric acid (HNO3) 70%, Analar, 2% H2SO4, Sigma Aldrich, 2% NaHCO3, pH buffers (4, 7 and 10) were obtained from Fisher Scientific. All chemicals were used as received. Raw material of palm kernel was collected from Sirte city, Libya. 2.1.3 Preparation of the Adsorbent Palm kernel sample was collected from Libya and used as adsorbent for removal of Cr(VI), Pb(II) and Cu(II) metal ion from aqueous using batch method of extraction. Sample preparation was conducted according to Ragwan et. al. [5]. The adsorbent material was firstly washed with distilled water to remove fines and dirt and dried at 110°C for 24 h. Then, it was crushed and sieved to a particle size of 0.5 mm, and stored in desiccator till its use in the adsorption experiments. 2.1.4 Chemical modification of adsorbent surface The previously described method [6] with slight modification was employed. The adsorbent was washed with deionized water until any leachable impurities due to free acid and adherent powder were removed. The samples were then treated with 2% H2SO4 (v/v) in an incubator at 110 C for 24 hand soaked with deionized water until the solution pH was stable. Afterwards, the adsorbent was
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Removal of Multi Heavy Metals in One Batch System …...
soaked in 2% NaHCO3 (w/v) till any residual acid left was removed. The acid-treated adsorbent was then dried overnight in an oven at110 C, cooled at room temperature, and stored in a desiccator.
2.1.5 Adsorbate solution A 1000 mg/L stock solution of Cr(VI) was prepared by dissolving 2.83 gm of K2Cr2O7 in deionized water. A 1000 mg/L stock solution of Cu(II) was prepared by dissolving 2.51 gm of CuSO4.5H2O in deionized water. The stock solution (1000 mg/L) of Pb(II) as [Pb(NO3)2] were obtained from Fisher Scientific. Stock solutions of different concentrations (mg/L) required for the adsorption studies were prepared by serial dilution of the stock solutions. 2.1.6 Waste water sample Waste water sample was collected from El-Souif waste crater plant, Alexandria, Egypt. 3 drops of
HNO3 were added to the collected sample in order to prevent metal precipitation. The sample was then transferred to the laboratory. 2.2. Experiments 2.2.1 Removal processes A 1.0 gm of palm kernel adsorbent and 150 mL of sample solution were used for each experiment divided the same volume for each metal. The initial concentrations of metal ions were 0.411, 0.424 and 0.86 gm/L for Cr(VI), Cu(II) and Pb(II), respectively. The pH was adjusted for each experiment to pH 3, 5, 7 and 9with using HCl (0.1N) and NaOH (0.1N). The mixture was shacked at 200 rpm for 60 min and after that a sample filtered. The residue of heavy metal cations in solutions was then measured by AAS. The same procedure was applied for the real water sample. A 150 ml of the sample was treated with 0.05 g of adsorbent and agitated on a mechanical shaker at 25°C (± 2), for a speed of 200 rpm for 60 min. The reaction stopped and the solution allowed settling down, filtered and the filtrate was analyzed for the residual amounts of metal ions using AA-spectrophotometer. 2.2.2 Data processing The percentage (%) removal of metal ion which is the ratio of the difference in metal concentration before and after adsorption, was calculated using Equation 1.
C −C Metal removal (%) = o e × 100 (1) Co Where: Co and Ce are the initial and equilibrium concentrations (mg/L) of metal ion after adsorption had taken place over a period of time t. The equilibrium adsorption capacity (qe) mg/g of adsorbent was calculated using Equation (2): (Co−Ce)V Equilibrium adsorption capacity (qe) = (2) m Where: V and m are the sample volume (mL) and the amount of adsorbent (gm) used, respectively.
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3. Results and Discussion
3.1 Waste water sample In order to demonstrate a practical application value of heavy metals removal, the adsorbent was used to treat a real waste water sample. Firstly, the sample was filtered and its pH value was measured and found equals to 7, salinity 2.68mg/L, conductivity 557ms, Tss 200mg/L, and TDS 430mg/L. For the other investigations, the pH was adjusted using HCL and NaOH (0.1N each). The maximum pH value was 7.00, which is not harmful for ecosystems and human use according to United States Environmental Production Agency (US-EPA) as listed in Table 1. The recommended level of pH by WHO and LSDW was between 6.5-8.5 [7]. The initial concentration of Cr(VI), Cu(II) and Pb(II) in the filtered sample were 0.181, 0.144 and 0.28 mg/L, respectively, as listed in Table 1.
Table 1. Physicochemical properties of El-souif waste water Test Unit WHO Libyan Standards El-Souif waste crater [6] pH --- 6.5-8.5 6.5-8.5 7.00 Ec ms/cm --- 0.800 557 TDS mg/L 500 500-1000 430 TSS mg/L -- -- 200 Salinity mg/L -- -- 2.68 Cr(IV) mg/L 0.05 0.05 0.18 Cu(II) mg/L --- 0.01-0.1 0.14 Pb(II) mg/L 0.01 0.05 0.28
3.2 Removal study 3.2.1 Removal of heavy metals After 60 min, the maximum removal for studied heavy metal ions {Cr(VI), Cu(II), and Pb(II)} onto palm kernel surface was studied and plotted in Figure 1. In order to study the effect of the pH value on the metal ion removal by palm kernel adsorbent, the pH value of the sample solution was adjusted to 3, 5, 7 and 9 using HCl and NaOH solutions.
It was found (Fig.1) that the maximum recovery of 70.5% (pH 3), 80.5% (pH 5) 73.5% (pH 9) for the metal ions (Cr, Cu, Pb), respectively. It was also noted that the percentage removal of Cr(VI) ions was decreased with increasing pH values from 70.5 to 13.4%. This could be due to the precipitation of the metal ions from aqueous solution [8]. The maximum removal for Cu(II) onto palm kernel surface was found at pH 5. However, increasing pH value has a slight effect on the removal of Cu(II) ions from the solution. A direct effect of pH was observed for the removal of
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Removal of Multi Heavy Metals in One Batch System …...
Pb(II) ions. These findings proved the ability of the present adsorbent material for the removal of heavy metals from aqueous samples.
100 Cu(II) Cr(IV)
80
(%)
l
a 60
ov 40
m e
R 20 0 3 5 7 9 pH Figure 1. The effect of pH on the removal of heavy metal ions onto surface of palm kernel.
Moreover, the present method was applied for the removal heavy metal ions from real a waste water samples which contain many different metal ions which could be enhanced or affect the adsorption capacity of metal ions onto the adsorbent surface.
Figure 2, shows the removal of Cr(IV), Cu(II) and Pb(II) ions onto the adsorbent surface at the optimum pH for each of the studied metal ions. Results, showed the maximum removal of studied metal ions was in order Pb(II) > Cu(II) > Cr(VI). This may be due to the competition between these metals or due to effect of other species present in the real wastewater crater. Finally, the results above clearly suggest that the used adsorbent material could be used as a natural adsorbent material for heavy metal ions removal from aqueous.
100 80
60
(%)
l
a 40 ov
m 20 e R 0
Cr(IV) Cu(II) Pb(II) Metal Ion Figure 2. Removal of Cr(VI), Cu(II) and Pb(II) from real waste water sample of pH 7
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Ragwan Mohamed and Alaa Mustafa
5. Conclusions
A real application case was performed to demonstrate the practical application value of adsorbents such as palm kernel in order to remove multi heavy metals from polluted real sample. For this purpose, a real sample was collected from El-Souif crater, Alexandria, Egypt. The results showed that the maximum removal of heavy metals in the same batch system onto palm kernel was in order Pb(II)>Cu(II)>Cr(VI) at the same conditions. The findings in this research that the adsorbents used here have high potential to remove Cr(VI), Cu(II) and pb(II) in real sample water.
Acknowledgment Authors would like to thank Department of Environmental Science, Alexandria University, Egypt and Department of Chemistry, Sirte University, Libya for their support to finish this project.
References
[1] Oguntimein, G. B., Biosorption of dye from textile wastewater effluent onto alkali treated dried sunflower seed hull and design of a batch adsorber. Journal of Environmental Chemical Engineering, 2015. 3(4): p. 2647-2661. [2] Bhuyan, M. and M. Bakar, Assessment of water quality in Halda River (the Major carp breeding ground) of Bangladesh. Pollution, 2017. 3(3): p. 429-441. [3] Erhayem, M., Al-Tohami F., Ragwan M. and Ahmida K., Isotherm, kinetic and thermodynamic studies for the sorption of mercury (II) onto activated carbon from Rosmarinus officinalis leaves. American Journal of Analytical Chemistry, 2015. 6(01): p. 1. [4] Inglezakis, V. J. and Zorpas, A. A., Heat of adsorption, adsorption energy and activation energy in adsorption and ion exchange systems. Desalination and Water Treatment, 2012. 39(1-3): p. 149-157. [5] Ragwan Mohamed, A. M. and Erhayem, M., Biosorption of Cr(VI) and Cu(II) by palm kernel powder and its potential application. International Journal of Environmental Science and Development, 2016. 7(11): p. 788-792. [6] Kadirvelu, K., Thamaraiselvi, K., Namasivayam, C., 2001. Adsorption of nickel(II) from aqueous solution onto activated carbon prepared from coirpith. Sep. Pur. Technol.24, 497–505. [7] J. Jumma, E. M. T.a.M.N.H., Groundwater pollution and wastewater management in Derna City, Libya. . Environ. J. Res., 2012. 6(1): p. 50. [8] Massai, H., Kinetic and batch equilibrium adsorption of Nickel (II) and Copper (II) ions from aqueous solution onto activated carbon prepared from Balanites aegyptiaca shells. American Chemical Science Journal, 2015. 6(1): p. 38-50.
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