DOCSLIB.ORG

Magnetically Induced Structural Difference in Ferrofluids And

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Magnetically Induced Structural Difference in Ferrofluids And Copyright © 2014 by American Scientific Publishers Journal of Nanofluids All rights reserved. Vol. 3, pp. 121–126, 2014 Printed in the United States of America (www.aspbs.com/jon) Magnetically Induced Structural Difference in Ferrofluids and Magnetorheological Fluids Hiral Virpura, Mayur Parmar, and Rajesh Patel∗ Department of Physics, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar 364002, India We have prepared ferrofluid using magnetic nanoparticles (∼ 10 nm) and magnetorheological fluid (MR fluid) using micron size (∼ 10 m) magnetic particles. We have observed striking difference in magnetically induced structure formation in both the fluids although both are classifications of magnetic fluids in a broad way. A field induced structural difference in chain formation, labyrinthine pattern, spikes formation (Rosensweig surface instability) and optical diffraction pattern is observed. The induced structural difference is mainly due to the magnetically induced dipolar interaction, field induced viscosity and surface tension in both the fluids. KEYWORDS: Magnetic Fluids, Induced Structures, Dipolar Interactions. 1. INTRODUCTION is between 10% to 40% to produce strong magnetorheo- ARTICLE Magnetic fluids can be classified in to two broad categories logical effect. In MR fluid the field induced aggregation [i] ferrofluid and [ii] magnetorheological fluids. Ferrofluid is a key factor for the magnetorheological behavior of is made up of a single domain magnetic nanoparti- the sample which is reversible. Particle sedimentation is cles (∼ 5–20 nm) dispersed in aIP: suitable 192.168.39.211 carrier liquid, On:1 Tue,one 28 ofSep the 2021 problems 22:21:30 with MR fluid whereas in ferrofluid whereas the MR fluid is made up ofCopyright: a micron size American mag- Scientificthe stability Publishers is long term. To overcome the particle sed- netic particles (∼ 2–20 m) dispersed in oilDelivered like car- byimentation Ingenta one can try to make bidispersed MR fluid.6–9 rier liquid.2 Magnetorheological fluid was introduced in Recently inversion of magnetic force between microparti- 1940’s2 whereas ferrofluid was introduced during 1960’s.3 cles and its effect on the magnetorheology in bidispersed Various applications of MR fluid includes Automotive magnetic fluid is studied.10 MR fluid is a yield stress fluid, clutches, brakes, polishing fluids, seat dampers, prosthetic ferrofluid is does not show field induced yield stress. MR knee damper, actuator systems, shock absorbers, etc.4 The fluid has strong dipolar interaction whereas ferrofluid has basic difference in MR fluid and ferrofluid starts with comparatively weak dipolar interactions as the magnetic their particle size. In ferrofluid the particle size range is susceptibility depends on the volume of the particles dis- about nanometer scale whereas for MR fluid the particle persed. In this paper we report striking difference in mag- size range is in micrometer scale. The magnetic nanopar- netic field induced structural difference such as particle ticles in ferrofluid are single domain whereas in MRF the aggregation behavior, labyrinthine pattern, spikes forma- magnetic particles can be multidomain. Consequently, the tion (Rosensweig surface instability) and optical diffrac- magnetic moment of micron size particles in MR fluid tion pattern and its field induced modulation. The observed is field induced and their Brownian motion is negligible, structural difference is due to the field induced strong dipo- while for ferrofluids the magnetic nanoparticles perform lar interactions, the field induced viscous behavior and sur- intense thermal motion. The field induced particle aggre- face tension in both the fluids. gation behavior in MR fluid is intense and under moderate magnetic field the fluid behaves like a solid due to large 2. EXPERIMENTAL DETAILS and thick aggregation of magnetic particles, in ferrofluid the field induced particle aggregation is less intense than Magnetic nanoparticles of Fe3O4 were prepared by classi- 1 MRF, it can produce magneto viscous effect5 butitdo cal co-precipitation method. The mixture of solution con- 3+ 2+ not behave like a solid the fluid behavior remains. The taining ferric (Fe ) chloride and ferrous (Fe ) sulphate volume concentration in MR fluid is generally high and was introduced in alkaline solution. The resulting mixture was continuously stirred for 20 min. at 10.5 pH to allow nanocrystallites to grow in size. Nanocrystallites were ∗Author to whom correspondence should be addressed. Emails: [email protected], [email protected] magnetically decanted and washed with distil water several Received: 18 December 2013 times to remove water-soluble impurities. To obtain sta- Accepted: 19 January 2014 ble ferrofluid these nanocrystallites were coated with oleic J. Nanofluids 2014, Vol. 3, No. 2 2169-432X/2014/3/121/006 doi:10.1166/jon.2014.1095 121 Magnetically Induced Structural Difference in Ferrofluids and Magnetorheological Fluids Virpura et al. 3. RESULTS AND DISCUSSION Magnetic fluids (MR fluids and ferrofluids) are composed of coated magnetic particles dispersed in a nonmagnetic liquid carrier. Under the effect of magnetic field they form head-to-toe chain like aggregation due to field induced dipolar interactions. The dipole moment of a magnetic par- ticle is proportional to its magnetic core volume with the relation given by m = VH, where V = d3/6 volume of the particle, d is diameter of the particle, is the magnetic susceptibility of the particle, H is the applied magnetic field. The dipole–dipole interaction potential between par- ticles i and j is given by, m · m 3m · r m · r dip = 1 i j − i ij j ij Uij 3 5 (1) 40 rij rij where rij is the displacement vector of the two particles m m and 0 is the vacuum permeability, i and j is the respective dipole moments. The magnetic dipole moment Fig. 1. Microscopic and TEM images of micron size magnetic particles = 3 of the particles can be given as m 4/3am Ms where (Fe3O4 and magnetic nanoparticles (Fe3O4) respectively. am is radius of the magnetic core and Ms is the satura- acid and dispersed in kerosene. The fluid was centrifuged tion magnetization of the particle material. The maximum at 12,000 RPM for 20 min to remove aggregates if any. attraction between the particles is obtained when particle dipoles are oriented head to tail configuration, it is equal to From the magnetization measurements of the ferrofluid, particle size (10.4 nm) and saturation magnetization of the m2 U =−2 0 (2) fluid (250 Oe) were determined. For preparation of mag- max 4 r 3 neto rheological fluid (MRF), commerciallyIP: 192.168.39.211 available On: iron Tue, 28 Sep 2021 22:21:30 particles were used. The initial concentrationCopyright: of magneticAmerican ScientificThe formation Publishers of aggregates is opposed by Brownian nanoparticles in ferrofluid is 4.8% whereas theDelivered concen- by dispersionIngenta and as such, the potential for field induced tration of micron size magnetic particles in MRF it is aggregation versus Brownian dispersion can be expressed 15%. Figure 1 shows the microscopic and TEM images of in terms of a governing dimensionless parameter, known micron size magnetic particles and magnetic nanoparticles as coupling constant, respectively. The visualization of chain dynamics under ARTICLE 2H 2V rotating magnetic field is observed using Magnus MLX = 0 (3) 12k T microscope. The magnification used is 100×. CCD cam- B era used is Samsung (BW-360CD) attached with the per- where 0 and H are free space permeability and applied sonal computer. The sample is placed at the centre of the magnetic field respectively. T and kB are absolute tem- pairs of Helmholtz coils to generate homogeneous mag- perature and Boltzmann constant. For 1 aggregation netic field up to 200 Oe in the plane of image. For spikes is highly favoured and 1 dispersion is favoured. Cal- formation (Rosensweig instability) and labyrinthine pat- culating its value for typical field strength of 10 kA/m tern observation, a layer of ferrofluid and MR fluid is and the susceptibility of iron particles with 10 m diam- mixed with miscible liquid and exposed to the perpendic- eter that is in the order of 108.5 Whereas for ferrofluid, ular magnetic field. An illuminating light is kept above it is approximately less than 5. The high value of makes the patter for the better visibility of the event. A capillary obvious that a strong tendency towards formation of chains viscometer having length 40 mm and diameter 0.5 mm and agglomerates is typical for a magnetorheological effect is calibrated at 25 C using three fluids: water, benzene, in MR fluids. and kerosene. Electromagnets were used to generate mag- Figure 2 shows the magnetic field induced chain for- netic field. The uncertainty involved in the viscosity mea- mation in ferrofluid and MR fluid at 500 Oe. It shows surement is ± 0.02 cP checked using standard samples. clear striking difference in a field induced aggregation in A He–Ne laser beam is passed through both the samples ferrofluid and MR fluid. It is visible that in ferrofluid the (after necessary dilution) for the detection and modulation size of the chain, distance between chains, formation of of diffraction pattern. For magnetic modulation of diffrac- multiple chain, shape of the chain like aggregate is quite tion pattern an electromagnet is used. The optical path different than that for MR fluid, for MR fluid the aggre- length of the sample is kept 2 mm. The observed on screen gation is caused by the association of multiple chains, diffraction pattern is recorded using CCD camera and a with structure of oblate shape in the direction of field, dis- computer. tance between chain is quite less, hence the dipolar forces 122 J. Nanofluids, 3, 121–126, 2014 Virpura et al. Magnetically Induced Structural Difference in Ferrofluids and Magnetorheological Fluids (a) Fig. 2. Magnetic field induced chain formation in ferrofluid and MR fluid at 500 Oe. The chains in ferrofluid are much thinner and chain separation is more than that of in MR fluid suggesting that field induced aggregation dynamics is quite different.
Load more

Recommended publications
  • Animafluid: a Dynamic Liquid Interface
    Animafluid: A Dynamic Liquid Interface Muhammad Ali Hashmi Heamin Kim Abstract 75 Amherst St. 75 Amherst St. In this paper the authors describe a new tangible liquid interface based on ferromagnetic fluid. Our interface Cambridge, Cambridge, combines properties of both liquid and magnetism in a MA 02139 USA MA 02139 USA single interface which allows the user to directly [email protected] [email protected] interact with the liquid interface. Our dynamic liquid interface, which we call Animafluid, uses the physical Artem Dementyev Amir Lazarovich qualities of ferromagnetic fluids in combination with 75 Amherst St. 75 Amherst St. pressure sensors, microcontrollers for real-time Cambridge, Cambridge, interaction that combines both physical input and output. Our implementation is different from existing MA 02139 USA MA 02139 USA ferrofluid interventions and projects that harness [email protected] [email protected] magnetic liquid properties of ferromagnetic fluids in the sense that it adds tangibility of radical atoms design methodology to ferromagnetic fluids, thereby changing Hye Soo Yang the scope of interaction with the ferromagnetic fluid in 75 Amherst St. a drastic manner. Cambridge, MA 02139 USA Author Keywords [email protected] Tangible Interface; Ferrofluid; Dynamic Liquid Interface; Radical Atoms; Programmable Materiality ACM Classification Keywords H.5.2. Information interfaces and Presentation; User Interfaces Introduction Copyright is held by the author/owner(s). Ferromagnetic liquid is a material that has magnetic CHI’13, April 27 – May 2, 2013, Paris, France. and liquid properties. Ferromagnetic fluids have been used in a variety of different ways in the field of fluid dynamics. Our implementation imparts tangibility to the Prior Work liquid interface thus providing the design features of Our work is informed by prior work done on “Radical Atoms”, which envisions human interactions electromagnets-based interfaces and ferromagnetic with dynamic materials in a computationally fluids.
    [Show full text]
  • Determining the Flow Curves for an Inverse Ferrofluid
    Korea-Australia Rheology Journal Vol. 20, No. 1, March 2008 pp. 35-42 Determining the flow curves for an inverse ferrofluid C. C. Ekwebelam and H. See* The School of Chemical and Biomolecular Engineering, The University of Sydney, Australia. NSW 2006 (Received Oct. 9, 2007; final revision received Jan. 30, 2008) Abstract An inverse ferrofluid composed of micron sized polymethylmethacrylate particles dispersed in ferrofluid was used to investigate the effects of test duration times on determining the flow curves of these materials under constant magnetic field. The results showed that flow curves determined using low duration times were most likely not measuring the steady state rheological response. However, at longer duration times, which are expected to correspond more to steady state behaviour, we noticed the occurrence of plateau and decreasing flow curves in the shear rate range of 0.004 s−1 to ~ 20 s−1, which suggest the presence of non- homogeneities and shear localization in the material. This behaviour was also reflected in the steady state results from shear start up tests performed over the same range of shear rates. The results indicate that care is required when interpreting flow curves obtained for inverse ferrofluids. Keywords : inverse ferrofluid, flow curve, shear localization 1. Introduction An IFF comprises a magnetisable carrier liquid, otherwise known as a ferrofluid, which is a colloidal dispersion of Field-responsive fluids are suspensions of micron-sized nano-sized magnetite particles. Into this we disperse particles which show a dramatic increase in flow resistance micron-sized non-magnetic solid particles, thereby pro- upon application of external magnetic or electrical fields.
    [Show full text]
  • 14Th U.S. National Congress on Computational Mechanics
    14th U.S. National Congress on Computational Mechanics Montréal • July 17-20, 2017 Congress Program at a Glance Sunday, July 16 Monday, July 17 Tuesday, July 18 Wednesday, July 19 Thursday, July 20 Registration Registration Registration Registration Short Course 7:30 am - 5:30 pm 7:30 am - 5:30 pm 7:30 am - 5:30 pm 7:30 am - 11:30 am Registration 8:00 am - 9:30 am 8:30 am - 9:00 am OPENING PL: Tarek Zohdi PL: Andrew Stuart PL: Mark Ainsworth PL: Anthony Patera 9:00 am - 9.45 am Chair: J.T. Oden Chair: T. Hughes Chair: L. Demkowicz Chair: M. Paraschivoiu Short Courses 9:45 am - 10:15 am Coffee Break Coffee Break Coffee Break Coffee Break 9:00 am - 12:00 pm 10:15 am - 11:55 am Technical Session TS1 Technical Session TS4 Technical Session TS7 Technical Session TS10 Lunch Break 11:55 am - 1:30 pm Lunch Break Lunch Break Lunch Break CLOSING aSPL: Raúl Tempone aSPL: Ron Miller aSPL: Eldad Haber 1:30 pm - 2:15 pm bSPL: Marino Arroyo bSPL: Beth Wingate bSPL: Margot Gerritsen Short Courses 2:15 pm - 2:30 pm Break-out Break-out Break-out 1:00 pm - 4:00 pm 2:30 pm - 4:10 pm Technical Session TS2 Technical Session TS5 Technical Session TS8 4:10 pm - 4:40 pm Coffee Break Coffee Break Coffee Break Congress Registration 2:00 pm - 8:00 pm 4:40 pm - 6:20 pm Technical Session TS3 Poster Session TS6 Technical Session TS9 Reception Opening in 517BC Cocktail Coffee Breaks in 517A 7th floor Terrace Plenary Lectures (PL) in 517BC 7:00 pm - 7:30 pm Cocktail and Banquet 6:00 pm - 8:00 pm Semi-Plenary Lectures (SPL): Banquet in 517BC aSPL in 517D 7:30 pm - 9:30 pm Viewing of Fireworks bSPL in 516BC Fireworks and Closing Reception Poster Session in 517A 10:00 pm - 10:30 pm on 7th floor Terrace On behalf of Polytechnique Montréal, it is my pleasure to welcome, to Montreal, the 14th U.S.
    [Show full text]
  • Magnetorheological Fluid and Its Applications
    International Journal of Current Engineering and Technology E-ISSN 2277 – 4106, P-ISSN 2347 – 5161 ©2017 INPRESSCO®, All Rights Reserved Available at http://inpressco.com/category/ijcet Research Article Magnetorheological Fluid and its Applications Pranav Gadekar*, V.S.Kanthale and N.D.Khaire Mechanical Department, MITCOE, Pune University, Pune, Maharashtra, India Accepted 12 March 2017, Available online 16 March 2017, Special Issue-7 (March 2017) Abstract A Magneto rheological Fluid (MRF) is a Smart fluid whose viscosity can be varied by application of magnetic field. The MR Fluid has vast applications in various engineering as well as day to day life. There is huge potential that this revolutionary material will provide many leading edge applications. The fluid has applications in various fields such as automotive industry, household applications, prosthetics, civil engineering, hydraulics, brakes and clutches, etc. Also there is a possible application of the fluid in reducing the effect of Gun Recoil. This paper will describe these applications and working of proposed application. Keywords: MR Fluid, Viscosity, Dampers, Prosthetics, Gun Recoil. 1. Introduction To take full advantage of MRF technologythe base fluid must have a low viscosity and it should be constant 1 Rheos is a Greek word to Flow. Rheology is the science with temperature. This is required for variation due to if material flow under external load conditions. The applied magnetic field to be more effective than natural word Magnetorheological Fluid means fluid whose viscosity. The presences of suspended particles make apparent viscosity increases, with application of base fluid thicker. Commonly used base fluids are MAGNETIC field. Also known as MR fluids, these fluids mineral oils, hydrocarbon oils, and Silicon oils.
    [Show full text]
  • Numerical Simulations of Heat and Mass Transfer Flows Utilizing
    CAPITAL UNIVERSITY OF SCIENCE AND TECHNOLOGY, ISLAMABAD Numerical Simulations of Heat and Mass Transfer Flows utilizing Nanofluid by Faisal Shahzad A thesis submitted in partial fulfillment for the degree of Doctor of Philosophy in the Faculty of Computing Department of Mathematics 2020 i Numerical Simulations of Heat and Mass Transfer Flows utilizing Nanofluid By Faisal Shahzad (DMT-143019) Dr. Noor Fadiya Mohd Noor, Assistant Professor University of Malaya, Kuala Lumpur, Malaysia (Foreign Evaluator 1) Dr. Fatma Ibrahim, Scientific Engineer Technische Universit¨atDortmund, Germany (Foreign Evaluator 2) Dr. Muhammad Sagheer (Thesis Supervisor) Dr. Muhammad Sagheer (Head, Department of Mathematics) Dr. Muhammad Abdul Qadir (Dean, Faculty of Computing) DEPARTMENT OF MATHEMATICS CAPITAL UNIVERSITY OF SCIENCE AND TECHNOLOGY ISLAMABAD 2020 ii Copyright c 2020 by Faisal Shahzad All rights reserved. No part of this thesis may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, by any information storage and retrieval system without the prior written permission of the author. iii Dedicated to my beloved father and adoring mother who remain alive within my heart vii List of Publications It is certified that following publication(s) have been made out of the research work that has been carried out for this thesis:- 1. F. Shahzad, M. Sagheer, and S. Hussain, \Numerical simulation of magnetohydrodynamic Jeffrey nanofluid flow and heat transfer over a stretching sheet considering Joule heating and viscous dissipation," AIP Advances, vol. 8, pp. 065316 (2018), DOI: 10.1063/1.5031447. 2. F. Shahzad, M. Sagheer, and S. Hussain, \MHD tangent hyperbolic nanofluid with chemical reaction, viscous dissipation and Joule heating effects,” AIP Advances, vol.
    [Show full text]
  • Development of an Energy-Harvesting Magnetorheological Fluid Damper
    University of Wollongong Research Online University of Wollongong Thesis Collection 1954-2016 University of Wollongong Thesis Collections 2016 Development of an energy-harvesting magnetorheological fluid damper Yun Lu University of Wollongong Follow this and additional works at: https://ro.uow.edu.au/theses University of Wollongong Copyright Warning You may print or download ONE copy of this document for the purpose of your own research or study. The University does not authorise you to copy, communicate or otherwise make available electronically to any other person any copyright material contained on this site. You are reminded of the following: This work is copyright. Apart from any use permitted under the Copyright Act 1968, no part of this work may be reproduced by any process, nor may any other exclusive right be exercised, without the permission of the author. Copyright owners are entitled to take legal action against persons who infringe their copyright. A reproduction of material that is protected by copyright may be a copyright infringement. A court may impose penalties and award damages in relation to offences and infringements relating to copyright material. Higher penalties may apply, and higher damages may be awarded, for offences and infringements involving the conversion of material into digital or electronic form. Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong. Recommended Citation Lu, Yun, Development of an energy-harvesting magnetorheological fluid damper, Master of Philosophy thesis, School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, 2016.
    [Show full text]
  • Magnetic Fluid Rheology and Flows
    Current Opinion in Colloid & Interface Science 10 (2005) 141 – 157 www.elsevier.com/locate/cocis Magnetic fluid rheology and flows Carlos Rinaldi a,1, Arlex Chaves a,1, Shihab Elborai b,2, Xiaowei (Tony) He b,2, Markus Zahn b,* a University of Puerto Rico, Department of Chemical Engineering, P.O. Box 9046, Mayaguez, PR 00681-9046, Puerto Rico b Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science and Laboratory for Electromagnetic and Electronic Systems, Cambridge, MA 02139, United States Available online 12 October 2005 Abstract Major recent advances: Magnetic fluid rheology and flow advances in the past year include: (1) generalization of the magnetization relaxation equation by Shliomis and Felderhof and generalization of the governing ferrohydrodynamic equations by Rosensweig and Felderhof; (2) advances in such biomedical applications as drug delivery, hyperthermia, and magnetic resonance imaging; (3) use of the antisymmetric part of the viscous stress tensor due to spin velocity to lower the effective magnetoviscosity to zero and negative values; (4) and ultrasound velocity profile measurements of spin-up flow showing counter-rotating surface and co-rotating volume flows in a uniform rotating magnetic field. Recent advances in magnetic fluid rheology and flows are reviewed including extensions of the governing magnetization relaxation and ferrohydrodynamic equations with a viscous stress tensor that has an antisymmetric part due to spin velocity; derivation of the magnetic susceptibility
    [Show full text]
  • Make a Ferrofluid
    Name: FFUNUN WWITHITH MAGNETS A Magnet that Drips: MAKING FERROFLUID A ferrofl uid is a special liquid with tiny magnetic particles fl oating around inside. Since these particles are attracted to each other, they must be coated with a special substance that prevents them from sticking together (so that the ferrofl uid remains fl uid). What makes ferrofl uid so special is that in the presence of an outside magnetic fi eld, each of the tiny particles becomes magnetized and the ferrofl uid condenses into a solid. In this activity you will be able to make and play with your own ferrofl uid and see how it behaves in the presence of a magnetic fi eld. WHAT YOU NEED: A bar magnet A napkin Vegetable Iron fi lings A shallow or sponge oil (from the hardware store) dish WHAT YOU’LL DO: Pour a bit of vegetable oil Pour iron fi lings into the 1. into a shallow dish, just 2. oil and mix the two until enough to make a thin they have become a thick, fi lm across the bottom. sludge-like material. This is your ferrofl uid! Use a napkin or sponge to absorb 3. any excess oil and allow the ferro- fl uid to become thicker. A good way to do this is to attach a magnet to the outside of the dish. This will solidify the fl uid and let you dab away extra oil. Turn over FFUNUN WWITHITH MAGNETS MAKINGDRAWING FERROFLUIDFIELD LINES Attach a magnet to the dish 4. containing the ferrofl uid; the fl uid will solidify and take the shape of the magnetic fi eld it is in! Removing the magnetic fi eld will allow the ferrofl uid to fl ow like a liquid again.
    [Show full text]
  • Complex Fluids in Energy Dissipating Systems
    applied sciences Review Complex Fluids in Energy Dissipating Systems Francisco J. Galindo-Rosales Centro de Estudos de Fenómenos de Transporte, Faculdade de Engenharia da Universidade do Porto, CP 4200-465 Porto, Portugal; [email protected] or [email protected]; Tel.: +351-925-107-116 Academic Editor: Fan-Gang Tseng Received: 19 May 2016; Accepted: 15 July 2016; Published: 25 July 2016 Abstract: The development of engineered systems for energy dissipation (or absorption) during impacts or vibrations is an increasing need in our society, mainly for human protection applications, but also for ensuring the right performance of different sort of devices, facilities or installations. In the last decade, new energy dissipating composites based on the use of certain complex fluids have flourished, due to their non-linear relationship between stress and strain rate depending on the flow/field configuration. This manuscript intends to review the different approaches reported in the literature, analyses the fundamental physics behind them and assess their pros and cons from the perspective of their practical applications. Keywords: complex fluids; electrorheological fluids; ferrofluids; magnetorheological fluids; electro-magneto-rheological fluids; shear thickening fluids; viscoelastic fluids; energy dissipating systems PACS: 82.70.-y; 83.10.-y; 83.60.-a; 83.80.-k 1. Introduction Preventing damage or discomfort resulting from any sort of external kinetic energy (impact or vibration) is an omnipresent problem in our society. On one hand, impacts and vibrations are responsible for several health problems. According to the European Injury Data Base (IDB), injuries due to accidents are killing one EU citizen every two minutes and disabling many more [1].
    [Show full text]
  • Arxiv:1808.04793V2 [Cond-Mat.Quant-Gas]
    Self-bound Bose-Fermi liquids in lower dimensions Debraj Rakshit, 1,2 Tomasz Karpiuk, 3 Paweł Zin, 4 Mirosław Brewczyk, 3 Maciej Lewenstein 2,5 and Mariusz Gajda 1 1 Institute of Physics, Polish Academy of Sciences, Aleja Lotnik´ow 32/46, PL-02668 Warsaw, Poland 2 ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Av. Carl Friedrich Gauss 3, 08860 Castelldefels (Barcelona), Spain 3 Wydział Fizyki, Uniwersytet w Białymstoku, ul. K. Ciołkowskiego 1L, 15-245 Białystok, Poland 4 National Centre for Nuclear Research, ul. Ho˙za 69, PL-00-681 Warsaw, Poland 5 ICREA, Pg. Lluis Companys 23, 08010 Barcelona, Spain Abstract. We study weakly interacting mixtures of ultracold atoms composed of bosonic and fermionic species in 2D and 1D. When interactions between particles are appropriately tuned, self-bound quantum liquids can be formed. We show that while formation of these droplets in 2D is due to the higher order correction terms contributing to the total energy and originating in quantum fluctuations, in 1D geometry the quantum fluctuations have a negligible role on formation of the self-bound systems. The leading mean-field interactions are then sufficient for droplet formation in 1D. We analyse stability conditions for 2D and 1D systems and predict values of equilibrium densities of droplets. PACS numbers: Submitted to: New J. Phys. 1. Introduction Although the physical space is three-dimensional, lower dimensional spaces are quite often considered on a theoretical ground. This is because they are simpler for analysis, nonetheless able to capture the basic physics of the three-dimensional space.
    [Show full text]
  • A Study of Active Engine Mounts
    A Study of Active Engine Mounts Examensarbete utfört i Reglerteknik vid Tekniska Högskolan i Linköping av Fredrik Jansson & Oskar Johansson Reg nr: LiTH-ISY-EX-3453-2003 Linköping 2003 F. JANSSON O. JOHANSSON A Study of Active Engine Mounts Examensarbete utfört i Reglerteknik vid Linköpings tekniska högskola av Fredrik Jansson och Oskar Johansson Reg nr: LiTH-ISY-EX-3453-2003 Supervisor: Andreas Eidehall Linköpings Universitet Claes Olsson Volvo Car Corporation Examiner: Professor Fredrik Gustafsson Linköpings Universitet Linköping 17th December 2003 F. JANSSON O. JOHANSSON A STUDY OF ACTIVE ENGINE MOUNTS Avdelning, Institution Datum Division, Department Date 2003-12-17 Institutionen för systemteknik 581 83 LINKÖPING Språk Rapporttyp ISBN Language Report category Svenska/Swedish Licentiatavhandling X Engelska/English X Examensarbete ISRN LITH-ISY-EX-3453-2003 C-uppsats D-uppsats Serietitel och serienummer ISSN Title of series, numbering Övrig rapport ____ URL för elektronisk version http://www.ep.liu.se/exjobb/isy/2003/3453/ Titel Studie av aktiva motorkuddar Title A Study of Active Engine Mounts Författare Fredrik Jansson and Oskar Johansson Author Sammanfattning Abstract Achieving better NVH (noise, vibration, and harshness) comfort necessitates the use of active technologies when product targets are beyond the scope of traditional passive insulators, absorbers, and dampers. Therefore, a lot of effort is now being put in order to develop various active solutions for vibration control, where the development of actuators is one part. Active hydraulic engine mounts have shown to be a promising actuator for vibration isolation with the benefits of the commonly used passive hydraulic engine mounts in addition to the active ones.
    [Show full text]
  • On the Rheology of Shear-Thickening and Magnetorheological Fluids Under Strong Confinement
    On the rheology of shear-thickening and magnetorheological fluids under strong confinement TESIS DOCTORAL Programa de Doctorado en Física y Ciencias del Espacio Elisa María Ortigosa Moya Directores Juan de Vicente Álvarez-Manzaneda Roque Isidro Hidalgo Álvarez Grupo de Física de Fluidos y Biocoloides Departamento de Física Aplicada 2020 Editor: Universidad de Granada. Tesis Doctorales Autor: Elisa María Ortigosa Moya ISBN: 978-84-1306-706-3 URI: http://hdl.handle.net/10481/65310 A mis padres y mi hermana. A los hijos de la tierra y los peces de ciudad. Agradecimientos Llega el momento de dedicar unas líneas de agradecimiento sincero a todos aquellos que de una u otra manera han estado a mi lado en días de sol, nubes y lluvia, ofreciéndome su ayuda, apoyo y tiempo para llevar a buen término esta tesis. En primer lugar quiero comenzar por dar las gracias a mis directores de tesis. A Juan, por ofrecerme la posibilidad de trabajar junto a él, un excepcio- nal investigador con capacidad para guiar el trabajo de cada vez más gente y hacerlo bien, además. Y a Roque, un insaciable aprendiz que contagia su ilu- sión por la ciencia. Gracias por lo aprendido y por vuestra confianza, consejos y paciencia durante estos años. Gracias también a los miembros del Departamento de Física Aplicada, en especial al Grupo de Física de Fluidos y Biocoloides, por dejarme aprender de vosotros en cada seminario y ayudarme en lo que he necesitado: Ana Belén, Julia, Alberto, Arturo, Teresa, Wagner, Curro y Miguel Ángel. A María, por su disposición y su sonrisa imborrable; a Pepe, compañero en el sótano con quien habría disfrutado en clase como alumna; a Delfi por sus firmas y cariño; a Miguel Cabrerizo, por acercar la ciencia a la gente; y especialmente a María José, Fernando y Stefania, por su constante ayuda en las prácticas de Biofísica cada curso.
    [Show full text]