DOCSLIB.ORG

Gradient-Based Optimization in Nonlinear Structural Dynamics

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Gradient-Based Optimization in Nonlinear Structural Dynamics Downloaded from orbit.dtu.dk on: Dec 21, 2017 Gradient-based optimization in nonlinear structural dynamics Dou, Suguang; Jensen, Jakob Søndergaard Publication date: 2015 Document Version Publisher's PDF, also known as Version of record Link back to DTU Orbit Citation (APA): Dou, S., & Jensen, J. S. (2015). Gradient-based optimization in nonlinear structural dynamics. DTU Mechanical Engineering. (DCAMM Special Report; No. S184). General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Gradient-based optimization in nonlinear structural dynamics PhD Thesis Suguang Dou DCAMM Special Report No. S184 April 2015 Gradient-based optimization in nonlinear structural dynamics by Suguang Dou SOLIDDEPT. OF MECHANICS MECHANICAL ENGINEERING Dept.Solid Mechanics of Mechanical Engineering TECHNICALTECHNICAL UNIVERSITYUNIVERSITY OFOF DENMARK DENMARK Title of the thesis: Gradient-based optimization in nonlinear structural dynamics Ph.D. student: Suguang Dou E-mail: [email protected] E-mail: [email protected] Address: Section of Solid Mechanics Department of Mechanical Engineering Technical University of Denmark Nils Koppels Alle,´ Building 404 2800 Kgs. Lyngby Denmark Supervisor: Jakob Søndergaard Jensen E-mail: [email protected] Address: CAMM – Centre for Acoustic-Mechanical Micro Systems Department of Electrical Engineering Technical University of Denmark Nils Koppels Alle,´ Building 352 2800 Kgs. Lyngby Denmark Copyright © 2015 Suguang Dou Preface This thesis is submitted in partial fulfillment of the requirements for obtaining the Ph.D. degree in mechanical engineering at the Technical University of Den- mark (DTU). The Ph.D. project was funded by European Research Council (ERC) through the project “Integrated Analysis & Design in Nonlinear Dynamics (INN- ODYN) ”. The project was carried out in Department of Mechanical Engineer- ing at DTU from May 1st, 2012 to April 30th, 2015. Professor Dr. techn. Jakob Søndergaard Jensen was the supervisor on the project. Part of the work was carried out during a five-month visit to Professor Dr. Steven W. Shaw and his research group at Michigan State University (MSU), United States. First and foremost, I would like to thank my supervisor for his inspiring and valuable support during the project. I am also grateful to Professor Steven Shaw and his Ph.D. student B. Scott Strachan for the productive collaboration. Further thanks are given to Professor Gaetan¨ Kerschen at University of Liege,` Belgium, Professor Cyril Touze´ at ENSTA-ParisTech, France, and Professor Steven Shaw, for the CISM course “Modal Analysis of Nonlinear Mechanical Systems”, held at Udine, Italy, 2012. Additional thanks are given to Associate Professor Silvan Schmid and Ph.D. student Maksymilian Kurek in Department of Micro- and Nan- otechnology at DTU for their active help in fabrication and tests of the optimized micro-mechanical structures. I would like to thank my colleagues in TopOpt Group and in Department of Mechanical Engineering at DTU. They have created a cheerful and inspiring working environment. Special thanks to Gerda Helene Fogt for the great help in many aspects. I also wish to thank my colleagues in Department of Mechanical Engineering at MSU for creating a friendly and welcoming atmosphere. Last but not the least, I wish to thank my family for their support and under- standing, in particular, to my wife, Fangxing Tian, for her love and thoughtful- ness. Lyngby, April 2015 Suguang Dou i Resum´e (in Danish) Ikke-lineariteter i mekaniske strukturer kan give anledning til rige dynamiske effekter. Pa˚ det seneste har ikke-lineær dynamik i mikromekaniske strukturer bidraget til udviklingen af nye Mikro-Elektro-Mekaniske Systemer (MEMS), for eksempel til ”atomic force” mikroskopi, passive frekvensdelere, frekvens stabil- isatorer, og resonator gyroskoper. For at muliggøre design og optimering af disse strukturer, er det nødvendigt at udvide de eksisterende optimeringsmetoder, der typisk er baseret pa˚ lineær dynamik, til at tage de ikke-lineære dynamiske effek- ter med i betragtning. I denne afhandling er der udviklet en metode til at modellere, analysere, karakterisere og optimere strukturer pa˚ basis af deres ikke-lineær dynamiske opførsel. Modelleringen baserer sig pa˚ ikke-lineær finite element analyse og den ikke-lineære frekvensrespons og ikke-lineære svingningsformer er beregnet ved hjælp af en harmonisk balance metode med højere ordens harmoniske kompo- nenter medtaget. I karakteriseringen er ikke-lineære modale koblingskoefficien- ter beregnet direkte ud fra den ikke-lineære finite element model. Dette har re- sulteret i udviklingen af en ny klasse af optimeringsproblemer. Den gradient- baserede optimering er udført ved hjælp følsomhedsanalyse baseret pa˚ den ad- jungerede metode, som er specielt velegnet til storskala optimeringsproblemer. Anvendeligheden af den udviklede metode er eksemplificeret ved optimeringen af plane rammekonstruktioner. Arbejdet har vist følgende resultater: amplitude og frekvens af den ikke-lineære resonante respons kan effektivt optimeres; super- harmoniske resonanser kan undertrykkes eller forstærkes; Ikke–lineære karakter- istika (hard/blød˚ ikke linearitet) kan kvalitativt manipuleres; og en størrelsesordens forbedring af væsentlige modale koblingskoefficienter kan opnas.˚ Undersøgelsen har vist lovende mulige applikationer inden for ikke-lineære mikromekaniske resonatorer. Dette baner ogsa˚ vejen for topologioptimering af deres komplekse ikke-lineære dynamik. ii Abstract The intrinsic nonlinearity of mechanical structures can give rise to rich nonlin- ear dynamics. Recently, nonlinear dynamics of micro-mechanical structures have contributed to developing new Micro-Electro-Mechanical Systems (MEMS), for example, atomic force microscope, passive frequency divider, frequency stabi- lization, and disk resonator gyroscope. For advanced design of these structures, it is of considerable value to extend current optimization in linear structural dy- namics into nonlinear structural dynamics. In this thesis, we present a framework for modelling, analysis, characteriza- tion, and optimization of nonlinear structural dynamics. In the modelling, non- linear finite elements are used. In the analysis, nonlinear frequency response and nonlinear normal modes are calculated based on a harmonic balance method with higher-order harmonics. In the characterization, nonlinear modal coupling coefficients are calculated directly from a nonlinear finite element model. Based on the analysis and the characterization, a new class of optimization problems is studied. In the optimization, design sensitivity analysis is performed by using the adjoint method which is suitable for large-scale structural optimization. The op- timization procedure is exemplified by the design of plane frame structures. The work has demonstrated the following results: the amplitude and the frequency of nonlinear resonance peak can be effectively optimized; the super-harmonic reso- nances can be either suppressed or enhanced; the hardening/softening behavior can be qualitatively changed; and an order-of-magnitude improvement of some essential modal coupling coefficients can be achieved. The study has shown promising applications in nonlinear micro-mechanical resonators. It also paves the way for topology optimization of complex nonlinear dynamics. iii Publications The following publications are part of the thesis [P1] S. Dou, J. S. Jensen, Optimization of nonlinear structural resonance using the incremental harmonic balance method, Journal of Sound and Vibration, 334, 239-254, 2015. [P2] S. Dou, B. S. Strachan, S. W. Shaw and J. S. Jensen, Structural optimization for nonlinear dynamic response. (To appear in the “A field guide to nonlin- earity in structural dynamics” issue of Philosophical Transactions A) [P3] S. Dou, J. S. Jensen, Optimization of hardening/softening behavior of plane frame structures using nonlinear normal modes. (Submitted for journal publication) [P4] S. Dou, J. S. Jensen, Optimal design of hardening and softening resonances of plane frame structures. Abstract presented at the 8th European Nonlinear Dynamics Conference, Vienna, Austria, 2014. [P5] S. Dou, J. S. Jensen, Analytical sensitivity analysis and topology optimiza- tion of nonlinear resonant structures with hardening and softening behav- ior. Abstract presented at the 17th U.S. National Congress on Theoretical and Applied Mechanics, East Lansing, Michigan, United States, 2014. iv Contents Preface i Resum´eii Abstract iii Publications iv Contents v 1 Introduction 1 1.1 Motivation and goals ........................... 1 1.2 Current development in nonlinear dynamics ............. 4 1.3 Gradient-based structural optimization ................ 5 1.4 Structure of the thesis ........................... 7 2 Methods for modelling, analysis and characterization
Load more

Recommended publications
  • Luminosity Tuning at the Large Hadron Collider
    Luminosity Tuning at the Large Hadron Collider Dissertation zur Erlangung des akademischen Titels Doktor der technischen Wissenschaft Vorgelegt der Technisch-Naturwissenschaftlichen Fakult¨at CERN-THESIS-2006-064 15/07/2006 der Technischen Universit¨at Graz Durchgefu¨hrt am europ¨aischen Kernforschungszentrum CERN, CH-1211 Genf, und am Institut fu¨r Theoretische Physik der TU-Graz,A-8010 Graz, von Walter Wittmer F¨ur meine Frau Eva und meine Kinder Maxi und Martin. Abstract By measuring and adjusting the β-functions at the interaction point (IP) the luminos- ity is being optimized. In LEP (Large Electron Positron Collider) this was done with the two closest doublet magnets. This approach is not applicable for the LHC (Large Hadron Collider) and RHIC (Relativistic Heavy Ion Collider) due to the asymmetric lattice. In addition in the LHC both beams share a common beam pipe through the inner triplet magnets (in these region changes of the magnetic field act on both beams). To control and adjust the β-functions without perturbation of other optics functions, quadrupole groups situated on both sides further away from the IP have to be used where the two beams are already separated. The quadrupoles are excited in specific linear combinations, forming the so-called “tuning knobs” for the IP β functions. For aspecific correction this knob is scaled by a common multiplier. The different meth- ods which were used to compute such knobs are discussed: (1) matching in MAD, (2) inversion and conditioning of the response matrix by singular value decomposition, and (3) conditioning the response matrix by multidimensional minimization using an adapted Moore Penrose method.
    [Show full text]
  • Alpha Proportionality and Penrose Square Root Law
    icPSIRS 2016: 3rd International Conference on Political Science, International Relations and Sociology Alpha Proportionality and Penrose Square Root Law Piotr Dniestrzańskia* *Corresponding author: Piotr Dniestrzański, [email protected] aWroclaw University of Economics, Komandorska Street 118/120,53-345 Wroclaw, Poland, [email protected] Abstract http://dx.doi.org/10.15405/epsbs.2016.05.03.4 Problem concerns the distribution of mandates in collegial bodies of communities of states. The number of delegates representing each member of community depends on the number of its population. The paper analyzes the fairness of different kinds of relationship involving the number of representatives in collegial bodies of communities of states, in search of the fairest relationship. The research aims at comparing different ideas of how the numbers of representatives are determined reflecting the population of member states. Literature review, elementary probabilistic tools and mathematical analysis of degressive proportionality are employed. The main result of the paper demonstrates that the two fundamentally different approaches to the problem of distribution of mandates in collegial bodies may lead to similar solutions. A probabilistic approach (based on the voting power) and the concept of degressive proportionality (without additional assumptions) do not exclude each other, but, quite the contrary, may complement each other. The Penrose law and the rule of degressive proportionality, when suitably interpreted, are two sides of the coin. Degressive proportionality, as written in the Lisbon Treaty, is a vague idea. © 2016 Published by Future Academy www.FutureAcademy.org.uk Keywords: Penrose square root law; degressive proportionality; European Parliament; voting power. 1. Introduction The influence of individual members of an organization, economic or political communities on decision making is one of the key issues in modern societies.
    [Show full text]
  • Global Governance and the Emergence of Global Institutions for the 21 St Century
    Downloaded from https://www.cambridge.org/core. IP address: 71.178.53.58, on 20 Jan 2020 at 19:24:33, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://www.cambridge.org/core/product/AF7D40B152C4CBEDB310EC5F40866A59 Downloaded from https://www.cambridge.org/core. IP address: 71.178.53.58, on 20 Jan 2020 at 19:24:33, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://www.cambridge.org/core/product/AF7D40B152C4CBEDB310EC5F40866A59 “In this outstanding volume, López-Claros, Dahl, and Groff document the existen- tial challenges facing our global institutions, from environmental decline and the failure of existing international security mechanisms to mass population flows and the crisis of sovereignty and civil society engagement. The resulting landscape might seem hopeless and overwhelming, if not for the authors’ innovative, wide-ranging, and thought-provoking recommendations for reshaping existing insti- tutions to expand their relevance and effectiveness. Their ideas for updating our seven-decades-old structures include creating an international peace force, ratifying a United Nations Bill of Rights, reforming the UN Security Council and Inter- national Monetary Fund, establishing a civil society chamber, and beyond. Readers may not endorse every one of their suggestions, but they are invited into a fascinat- ing game of ‘what if?’ and ‘why not?’ It is an invitation that should not be missed.” Ambassador Donald Steinberg, Board member, Center for Strategic and International Studies “The current UN-based world system of governance, largely formulated in the mid-20th century after the Second World War, is not up to dealing satisfactorily with 21st-century problems.
    [Show full text]
  • Developing International Democracy
    Developing International Democracy Published by Committee for a Democratic U.N. Berlin, Germany, 2010 Copyright © Committee for a Democratic U.N., 2010 2nd edition The first edition was published by Horizonte Publishers, Stuttgart, Germany, in 2005 Cover designed by Jeannette Lee www.kdun.org ISBN 978-3-942282-02-4 Developing International Democracy For a Parliamentary Assembly at the United Nations A Strategy Paper of the Committee for a Democratic U.N. Andreas Bummel COMMITTEE FOR A DEMOCRATIC U.N. The Committee for a Democratic U.N. was founded to support the development of global democracy. An important milestone would be the establishment of a United Nations Parliamentary Assembly. The general rationale of the proposal is presented in this paper. This second edition includes extensive documentation in the annex. Praise for the first edition: “This strategy paper explains in an exceptionally tangible and realistic way how the path to international democracy could look like.” — Jo Leinen, Member of the European Parliament and Co-Chair of the Parliamentary Advisory Group of the Campaign for the Establishment of a UN Parliamentary Assembly “This paper is one of the most important and comprehensive contributions to this vital issue in the last twenty years.” — William R. Pace, Executive Director of the World Federalist Movement- Institute for Global Policy Contents Preface to the 2nd edition ................................................................................ 6 Conclusions ...................................................................................................
    [Show full text]
  • Fuel Cycle Studies on Minor Actinide Burning in Gas Cooled Fast Reactors
    FUEL CYCLE STUDIES ON MINOR ACTINIDE BURNING IN GAS COOLED FAST REACTORS M. Szieberth†, M. Halász, T. Reiss‡, S. Fehér Institute of Nuclear Techniques, Budapest University of Technology and Economics, H-1111 Budapest, Műegyetem rkp. 9., Hungary Abstract. The gas cooled fast reactor (GFR) is a Generation IV reactor type considered as an alternative fast neutron reactor design aimed to improve the sustainability of nuclear energy by improving the uranium utilization efficiency. Besides fuel breeding the especially fast neutron spectrum of the GFR also provides excellent opportunities for minor actinide (MA) burning. Development of the design of a 2400 MWth full-scale and a 70 MWth demonstrator GFR (ALLEGRO) is going on in the Euratom sponsored GoFastR project. The paper presents fuel cycle studies performed at the Budapest University of Technology and Economics (BME) for the assessment of the transmutational capabilities of the 2400 MWth GFR design in the framework of the GoFastR project. Homogeneous recycling of minor actinides into the GFRs was considered and their MA consumption was investigated. The results confirm the expectation that GRFs can also be applied for burning of MAs produced in other reactors. 1. Introduction Fast reactors have the unique ability to be sustainable by, not only being able to generate their own fuel, but through being able to burn minor actinides to reduce the quantity and radiotoxicity of nuclear wastes. The latter ability enables fast reactors to not only burn the minor actinides produced by themselves but, in addition, the minor actinides arising from legacy wastes and thermal reactors in the nuclear park.
    [Show full text]
  • Informal Bargaining in Bicameral Systems: Explaining Delegation by the Council of the European Union and the European Parliament
    Informal bargaining in bicameral systems: Explaining delegation by the Council of the European Union and the European Parliament Philipp Broniecki September 13, 2018 A dissertation submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy of University College London. Declaration I, Philipp Broniecki, confirm that the work presented in this thesis is my own. Where in- formation has been derived from other sources, I confirm that this has been indicated in the thesis. 2 Abstract This project is about the effects of institutional design on decision-making in the European Union. Specifically: delegation to informal inter-institutional legislative bargaining (the `infor- mal arena'). I develop a spatial complete information model to explain the decision to delegate to the `informal arena' and test its empirical implications. The meta-theoretical umbrella for this project is New Institutionalism (more specifically, Rational Choice Institutionalism) and I view the decision to delegate through a principal-agent lens, i.e., delegation may result in policy outcomes that differ from counterfactual non-delegated acts (agency-drift). I contribute to the theoretical and empirical literatures on informal law-making in the European Union and legislative organisation more generally. In the EU, the `formal arena' co-exists with the `informal arena.' In the formal arena, bills shuttle back and forth between two chambers in a maximum of three reading stages. In the informal arena, inter-institutional negotiations are delegated. The delegations meet behind closed doors and the resulting compromise is rubber-stamped by the parent chambers. The extant literature suggests that law-making in the informal arena leads to agency-drift.
    [Show full text]
  • The Blend of Poetry and Document in the Photographical Artist's Book the Road Is Wider Than Long by Roland Penrose
    Interfaces Image Texte Language 43 | 2020 Création/Destruction The blend of poetry and document in the photographical artist’s book The Road is Wider than Long by Roland Penrose (1939) Anne Reverseau Electronic version URL: http://journals.openedition.org/interfaces/810 DOI: 10.4000/interfaces.810 ISSN: 2647-6754 Publisher: Université de Bourgogne, Université de Paris, College of the Holy Cross Printed version Date of publication: 15 July 2020 Number of pages: 125-141 ISSN: 1164-6225 Electronic reference Anne Reverseau, « The blend of poetry and document in the photographical artist’s book The Road is Wider than Long by Roland Penrose (1939) », Interfaces [Online], 43 | 2020, Online since 15 July 2020, connection on 31 December 2020. URL : http://journals.openedition.org/interfaces/810 ; DOI : https:// doi.org/10.4000/interfaces.810 Les contenus de la revue Interfaces sont mis à disposition selon les termes de la Licence Creative Commons Attribution 4.0 International. THE BLEND OF POETRY AND DOCUMENT IN THE PHOTOGRAPHICAL ARTIST’S BOOK THE ROAD IS WIDER THAN LONG BY ROLAND PENROSE (1939) Anne Reverseau (FNRS) Université Catholique de Louvain Abstract: The Road is Wider than Long is a paradoxical artist’s book created by Roland Penrose in 1939. At the same time documentary and poetic, a travel report and a lyrical production, it comprises free verse, typographic poetry, “papiers collés”, and photographs. This heterogeneous nature allows to explore the contrasts and contradictions between but also the coming together of avant-garde poetry and photography. First, this article shows how The Road is Wider than Long draws from amateur practices by focusing on Penrose’s method of handling the pictures.
    [Show full text]
  • A World Parliamentary Assembly: a Catalyst for Change
    5 A World Parliamentary Assembly: A Catalyst for Change The assembly’s very existence would also help promote the peaceful resolution of inter- national conflicts. Because elected delegates would represent individuals and society instead of states, they would not have to vote along national lines. Coalitions would likely form on other bases, such as world-view, political orientation, and interests. Compromises among such competing but nonmilitarized coalitions might eventually undermine reliance on the current war system, in which international decisions are still made by heavily armed nations that are poised to destroy one another. In due course, international relations might more closely 1 resemble policymaking within the most democratic societies in the world. Richard Falk and Andrew Strauss The United Nations is not a world government, but it is our primary forum to discuss issues and risks of global significance in an increasingly interdependent world. Whether it is perceived as being imbued with a strong dose of democratic legitimacy matters a great deal for its effectiveness, credibility, and ability to become a problem-solving organization. For all of these reasons, and for those expressed below, we suggest the establishment of a significantly reformed General Assembly as explained in Chapter 4. Until such significant reforms are realized, in this chapter we also sketch out the possibility of an interim “World Parliamentary Assembly” that could serve as an advisory body to the General Assembly, acting as a type of “second chamber,” and greatly enhancing the legitimacy of the UN as a global decision- maker as soon as possible. This is particularly important because the United Nations General Assembly itself on a number of occasions has expressed its unambiguous support for democratic forms of governance for its members.
    [Show full text]
  • Inverse Kinematics Data Adaptation to Non-Standard Modular Robotic Arm Consisting of Unique Rotational Modules
    applied sciences Article Inverse Kinematics Data Adaptation to Non-Standard Modular Robotic Arm Consisting of Unique Rotational Modules Štefan Ondoˇcko 1, Jozef Svetlík 1,* , Michal Šašala 1, Zdenko Bobovský 2 , Tomáš Stejskal 1, Jozef Dobránsky 3 , Peter Demeˇc 1 and Lukáš Hrivniak 1 1 Department of Manufacturing Machinery and Robotics, Faculty of Mechanical Engineering, The Technical University of Košice, Letná 9, 04001 Košice, Slovakia; [email protected] (Š.O.); [email protected] (M.Š.); [email protected] (T.S.); [email protected] (P.D.); [email protected] (L.H.) 2 Department of Robotics, Faculty of Mechanical Engineering, VSB—TU Ostrava, 17. listopadu 2172/15, 708 00 Ostrava-Poruba, Czech Republic; [email protected] 3 Department of Automotive and Manufacturing Technologies, Faculty of Manufacturing Technologies with a seat in Prešov, Technical University of Košice, Štúrova 31, 08001 Prešov, Slovakia; [email protected] * Correspondence: [email protected]; Tel.: +421-55-602-2195 Abstract: The paper describes the original robotic arm designed by our team kinematic design consisting of universal rotational modules (URM). The philosophy of modularity plays quite an important role when it comes to this mechanism since the individual modules will be the building blocks of the entire robotic arm. This is a serial kinematic chain with six degrees of freedom of unlimited rotation. It was modeled in three different environments to obtain the necessary visualizations, data, measurements, structural changes measurements and structural changes. In the environment of the CoppeliaSim Edu, it was constructed mainly to obtain the joints coordinates Citation: Ondoˇcko,t.; Svetlík, J.; matching the description of a certain spatial trajectory with an option to test the software potential in Šašala, M.; Bobovský, Z.; Stejskal, T.; future inverse task calculations.
    [Show full text]
  • Short Term Wind Speed Forecasting Using Hybrid ELM Approach
    ISSN (Print) : 0974-6846 Indian Journal of Science and Technology, Vol 10(8), DOI: 10.17485/ijst/2017/v10i8/104479, February 2017 ISSN (Online) : 0974-5645 Short Term Wind Speed Forecasting using Hybrid ELM Approach Mahaboob Shareef Syed* and S. Sivanagaraju EEE Department, UCEK, JNTUK, Kakinada - 533003, Andhra Pradesh, India; [email protected], [email protected] Abstract Objectives: To enrich the accuracy of the wind speed forecasting to calculate wind power generation connecting to grid with the help of machine learning algorithms. Methods/Statistical Analysis: A novel hybrid method, Persistence - Extreme Learning Machine (P-ELM) algorithm is proposed. It uses the features of both Persistent and Extreme Learning Machine algorithms. The historical data of meteorological parameters viz. pressure, temperature and past wind speeds are considered as input parameters and wind speed for the next instant as the output, measured at one hour interval for a period of a month are used for the study. Findings: The forecasting is carried out for three areas Guntur, Vijayawada and Ongole of Andhra Pradesh state, India for winter, summer and rainy seasons. The performance of the P-ELM is evaluated in terms of Mean Absolute Error (MAE) and Root Mean Square Error (RMSE). From the results obtained it can be concluded that the P-ELM algorithm leaves behind the fundamental Persistent and Extreme Learning Machine algorithm not only in terms of error metrics but also in simulation time. The entire simulation is carried out with the help of MATLAB 2013a software. Application/Improvements: This technique is very much helpful in real time forecasting of wind speed to avoid the high level of uncertainty involved in wind generation, there by increases the power system security and stability.
    [Show full text]
  • Exploring the Cultural Meaning of the Natural Sciences in Contemporary
    Rhetoric and Representation: Exploring the Cultural Meaning of the Natural Sciences in Contemporary Popular Science Writing and Literature Juuso Aarnio Doctoral Dissertation, Department of English, University of Helsinki 2008 © Juuso Aarnio 2008 ISBN 978-952-92-3478-3 (paperback) ISBN 978-952-10-4581-3 (PDF) Helsinki University Printing House Helsinki 2008 Abstract During the last twenty-five years, literary critics have become increasingly aware of the complexities surrounding the relationship between the so-called two cultures of science and literature. Instead of regarding them as antagonistic endeavours, many now argue that the two emerge from the common ground of language, and often deal with and respond to similar questions, although their methods of doing it are different. While this thesis does not suggest that science should simply be treated as an instance of discursive practices, it shows that our understanding of scientific ideas is to a considerable extent guided by the employment of linguistic structures that allow genres of science writing such as popular science to express arguments in a persuasive manner. In this task figurative language plays a significant role, as it helps create a close link between content and form, the latter not only stylistically supporting the former but also frequently epitomizing the philosophy behind what is said and establishing various kinds of argumentative logic. As many previous studies have tended to focus only on the use of metaphor in scientific arguments, this thesis seeks to widen the scope by also analysing the use of other figures of speech. Because of its important role in popular science writing, figurative language constitutes a bridge to literature employing scientific ideas.
    [Show full text]
  • A Proposal to Reform United Nations' Organizational Structure
    UN REFORM 1 Running head: UN REFORM United in Progress: A Proposal to Reform United Nations’ Organizational Structure Zack A. Tucker University of Arkansas at Monticello UN REFORM 2 Abstract This paper will attempt to look at the current structure of the United Nation and formulate proposed reform to better solve the three issues currently facing the UN as an international political organization. International Relation theory will be used to formulate structural changes to UN. The purpose of the structural re-organization of the UN will be to attempt to limit the availability of a small elite group of member states to control the UN; to halt the advancement of globalism as a threat to member states; and to enable the effectiveness of the UN to prevent conflict and to delivery and protect humanitarian services, by ensure trust in the UN organization. UN REFORM 3 United in Progress: A Proposal to Reform United Nations’ Organizational Structure "Every day we are reminded of the need for a strengthened United Nations, as we face a growing array of new challenges, including humanitarian crises, human rights violations, armed conflicts and important health and environmental concerns. Seldom has the United Nations been called upon to do so much for so many. I am determined to breathe new life and inject renewed confidence into a strengthened United Nations firmly anchored in the twenty- first century, and which is effective, efficient, coherent and accountable." UN Secretary-General Ban Ki-moon INTRODUCTION Ban Ki-moon, Secretary-General of the United Nations, delivered an arousing address before the UN General Assembly in April 2008.
    [Show full text]