Modélisation des phénomènes de diffusion thermique dans un milieu fini homogène en vue de l’analyse, de la synthèse et de la validation de commandes robustes

The work of this thesis concerns the study of the thermal diffusion phenomena to have a model (white box approach) for the analysis, the frequency synthesis and the time validation of robust commands. The Part 1 composed of chapter 1 focuses on the definitions and the interpretations of the integro-differential non-integer operator. The simulation problem in the time domain of the fractional differential systems is specified. Part 2 entitled "Analytical Study" includes two chapters whose objective is to make a detailed analysis of the fractional order behavior, first in a semi-infinite medium (chapter 2), then in a finite medium (chapter 3). Part 3, entitled "Numerical simulation of time responses" combining two chapters (4 and 5), aims the implementation of the "thermal process" plant (model validation of a finite medium) of a simulator of the thermal control loop time responses.Les travaux de cette thèse concernent l’étude des phénomènes de diffusion thermique en vue de disposer de modèles de connaissances (approche boîte blanche) pour l’analyse, la synthèse fréquentielle et la validation temporelle de commandes robustes. La Partie 1 composée du chapitre 1 se focalise sur les définitions et les interprétations de l’opérateur intégro-différentiel non entier. La problématique de la simulation, dans le domaine temporel, des SDNE est précisée. La Partie 2 intitulée "Etude analytique" regroupe deux chapitres dont l’objectif est de faire une analyse fine des comportements d’ordre non entier, d’abord dans un milieu semi-infini (chapitre 2), puis dans un milieu fini (chapitre 3). La Partie 3, intitulée "Simulation numérique des réponses temporelles" regroupant deux chapitres (4 et 5), a pour finalité la mise en oeuvre de la partie « Procédé thermique » (modèle de validation d’un milieu fini) d’un simulateur des réponses temporelles d’une boucle de régulation thermique

Metodologia baseada em algoritmos evolutivos para otimização de controladores de ordem fracionária

Orientador: Gustavo Henrique da Costa OliveiraCoorientador: Gideon Villar LeandroTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Engenharia Elétrica. Defesa : Curitiba, 06/12/2022Inclui referências: p. 159-171Área de concentração: Engenharia ElétricaResumo: Nos últimos anos, o cálculo de ordem fracionária ganhou muita atenção, especialmente no campo da teoria de sistemas dinâmicos e do projeto de sistemas de controle. Algoritmos de controle com ordem fracionária permitem expandir a quantidade de parâmetros de projeto visando melhorar o desempenho do sistema em malha fechada. No entanto, os graus de liberdade são acompanhados com uma complexidade na síntese. Dentro dessa perspectiva, encontra-se o controlador PID de ordem fracionária (FOPID), que possui as ordens integral e diferencial ajustáveis, criando a possibilidade de fornecer melhor desempenho de controle, desde que corretamente sintonizado. Da mesma forma, a sintonia do controlador CRONE e suas gerações também é um desafio, onde a escolha incorreta dos parâmetros pode comprometer o desempenho do controlador. Em vista disso, este trabalho apresenta três objetivos principais, sendo o primeiro uma nova estratégia híbrida de controle, chamada AFOPID. Nesta estratégia, os cinco parâmetros do FOPID são sintonizados online de forma que, na ocorrência de alguma perturbação, a Lógica Fuzzy atualiza os coeficientes kp, ki e kd do FOPID para adaptar a malha fechada à nova condição de operação. Em seguida, os coeficientes fracionários (lambda) e µ, que são as ordens integral e diferencial do controlador, são atualizados usando um algoritmo de Evolução Diferencial (DE). Para fins de validação da metodologia proposta, uma planta de uma usina hidrelétrica baseada em um sistema real é utilizada. Através dos resultados, percebeu-se que o sistema híbrido melhorou a solução geral, fornecendo melhor desempenho em malha fechada do que soluções semelhantes, o que pôde ser comprovado através da análise dos índices de desempenho ISE, ITAE e ITSE. O segundo objetivo desta tese consiste na proposta de um algoritmo de otimização multiobjetivo para os controladores CRONE gerações 1 e 2. Para tanto, utiliza-se o algoritmo NSGA-II Multiobjetivo baseado em dois objetivos principais: (i) Minimizar o sinal de controle; (ii) Reduzir o erro em regime permanente. Os resultados mostraram que além de facilitar o processo de escolha dos parâmetros, não dependendo tanto do conhecimento do projetista, o controlador otimizado conseguiu fornecer bons níveis de desempenho, ou seja, minimizou o sinal de controle e reduziu o erro em regime permanente. Por fim, como terceiro objetivo deste trabalho, tem-se o desenvolvimento de uma plataforma computacional chamada UFPR-FracControl. A plataforma contém os controladores CRONE 1 e 2, convencional e otimizado, FOPID, PID convencional e, visa a utilização desses controladores por usuários não especialistas. Os resultados demonstraram que esta nova plataforma facilitará o uso de sistemas de controle de ordem fracionária pelo fato de ser leve, não depender de instalação, não depender de licenças e pelo fato de ser de fácil implementação. Por fim, conclui-se que os três objetivos aqui propostos obtiveram sucesso em melhorar o desempenho e facilitar o uso dos controladores de ordem fracionária.Abstract: In recent years, fractional order calculus has gained a lot of attention, especially in the field of dynamical system theory and control system design. Control algorithms with fractional order allow expanding the number of design parameters to improve the performance of the closed-loop system. However, the degrees of freedom are accompanied by complexity in the synthesis. Within this perspective, there is the fractional order PID controller (FOPID), which has adjustable integral and differential orders, creating the possibility of providing better control performance, as long as it is correctly tuned. Likewise, the tuning of the CRONE controller and its generations is also a challenge, where the incorrect choice of parameters can compromise the performance of the controller. Given this, this work presents three main objectives, the first being a new hybrid control strategy, called AFOPID. In this strategy, the five parameters of the FOPID are tuned online so that, in the event of any disturbance, the Logic Fuzzy updates the coefficients kp, ki and kd of the FOPID to adapt the closed loop to the new operating condition. Next, the fractional coefficients (lambda) and µ, which are the integral and differential orders of the controller, are updated using a Differential Evolution (DE) algorithm. To validate the proposed methodology, a plant of a hydroelectric plant based on a real system is used. Through the results, it was noticed that the hybrid system improved the overall solution, providing better closed-loop performance than similar solutions, which could be proven through the analysis of the ISE, ITAE, and ITSE performance indexes. The second objective of this thesis consists in proposing a multiobjective optimization algorithm for CRONE controllers generations 1 and 2. For this purpose, the NSGA-II Multiobjective algorithm is used based on two main objectives: (i) Minimize the control signal; (ii) Reduce the steady-state error. The results showed that in addition to facilitating the process of choosing the parameters, not depending so much on the designer's knowledge, the optimized controller was able to provide good levels of performance, that is, it minimized the control signal and reduced the steady-state error. Finally, as the third objective of this work, there is the development of a computational platform called UFPR-FracControl. The platform contains CRONE 1 and 2 controllers, conventional and optimized, FOPID, and conventional PID, and aims to use these controllers by non-specialist users. The results showed that this new platform will facilitate the use of fractional order control systems because it is lightweight, does not depend on installation, does not depend on licenses, and because it is easy to implement. Finally, it is concluded that the three objectives proposed here were successful in improving performance and facilitating the use of fractional order controllers

Nanoscale heat conduction with applications in nanoelectronics and thermoelectrics

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references.When the device or structure characteristic length scales are comparable to the mean free path and wavelength of energy carriers (electrons, photons, phonons, and molecules) or the time of interest is on the same order as the carrier relaxation time, conventional heat transfer theory is no longer valid. Tremendous progress has been made in the past two decades to understand and characterize heat transfer in nanostructures. However most work in the last decade has focused on heat transfer in simple nanostructures, such as thin films, superlattices and nanowires. In reality, there is a demand to study transport process in complex nanostructures for engineering applications, such as heat transfer in nanoelectronic devices and the thermal conductivity in nanocomposites which consists of nanowires or nanoparticles embedded in a matrix material. Another class of problems which are rich in physics and might be explored for better design of both nanoelectronic devices and energy conversion materials and devices are coupled electron and phonon transport. Experimentally, most past work has been focused on thermal conductivity characterization of various nanostructures and very little has been done on the fundamental transport properties of energy carriers.(cont.) This thesis work contributes to the following aspects of heat transfer, nanoelectronics, and thermoelectrics. 1) Simulation tools are developed for transient phonon transport in multidimensional nanostructures and used to predict the size effect on the temperature rise surrounding a nanoscale heat source, which mimics the heating issue in nano-MOSFETs. 2) Semiconductor nanocomposites are proposed for highly efficient thermoelectric materials development where low thermal conductivity is a blessing for efficiency enhancement. Both the deterministic solution and Monte Carlo simulation of the phonon Boltzmann equation are established to study the size effect on the thermal conductivity of nanocomposites where nanoparticles and nanowires are embedded in a host material. 3) Explored the possibility of creating nonequilibrium conditions between electrons and phonons in thermoelectric materials using high energy flux coupling to electrons through surface plasmons, and thus to develop highly efficient thermoelectric devices.(cont.) 4) Established a sub-pico second optical pump-probe measurement system where a femtosecond laser is employed and explored the possibility of extracting phonon reflectivity at interfaces and the phonon relaxation time in a material, which are the two most fundamental phonon properties for nanoscale energy transport from the pump-probe measurements.by Ronggui Yang.Ph.D

Model development for numerical simulation of the behaviors of pH-stimulus responsive hydrogels

Ph.DDOCTOR OF PHILOSOPH

Uncovering the role of free volume in biomaterials and biological matter

134 p.Uncovering the role of free volume in biomaterials and biological matterDoctoral Thesis by Eneko AxpeSupervised by Fernando Plazaola and Jose Angel GarcíaIn order to understand the role that free volume holes play in several properties of biomaterials (as shape memory polymers for medical applications or scaffolds for tissue engineering) and biological matter (as lipid membranes or living cancer cells), a novel positron annihilation lifetime spectrometer has been designed and fabricated. It has been successfully measured then the free volume hole size and distribution in these materials. This work has been mainly carried out at the University of the Basque Country UPV/EHU and in part in two research stays in the University of Oxford in 2014 and 15

Advances in Optofluidics

Optofluidics a niche research field that integrates optics with microfluidics. It started with elegant demonstrations of the passive interaction of light and liquid media such as liquid waveguides and liquid tunable lenses. Recently, the optofluidics continues the advance in liquid-based optical devices/systems. In addition, it has expanded rapidly into many other fields that involve lightwave (or photon) and liquid media. This Special Issue invites review articles (only review articles) that update the latest progress of the optofluidics in various aspects, such as new functional devices, new integrated systems, new fabrication techniques, new applications, etc. It covers, but is not limited to, topics such as micro-optics in liquid media, optofluidic sensors, integrated micro-optical systems, displays, optofluidics-on-fibers, optofluidic manipulation, energy and environmental applciations, and so on

Functional heterointerfaces via electromodulation spectroscopy

Appendix missing. Complete copy held in the Manuscripts Reading Room, Cambridge University Library, classmark PhD.33388.Functional heterojunctions in organic electronic devices are interfaces formed either between a conducting electrode and an organic semiconductor or between two different organic semiconductors in blended and multilayered structures. This thesis is primarily concerned with the energy level alignment and the interfacial electronic structures at functional heterojunctions encountered in electronic devices made with solution-processable semiconducting polymers. Investigations on the electronic structures across these heterointerfaces are performed with the combined use of electromodulation and photoemission spectroscopic techniques. Electromodulation and ultraviolet photoemission spectroscopic techniques enable direct determination of the surface work functions of electrodes at the electrode/semiconducting polymer interfaces. We overcame the inherent problems faced by electromodulation spectroscopy, which undermine accurate determination of interfacial electronic structures, by performing electroabsorption (EA) measurements at reduced temperatures. We showed in this thesis that low-temperature EA spectroscopy is a surface sensitive technique that can determine the interface electronic structures in electrode/polymer semiconductor/electrode diodes. Using this technique, we demonstrated that the energy level alignments in these solution-processed organic electronic devices are determined by the surface work functions of passivated metals rather than by those of clean metals encountered in ultrahigh vacuum. This thesis also discloses our studies on the electronic structures in polymeric diodes with type II donor-acceptor heterojunctions using the EA spectroscopy. We showed that minimising meausurement temperature and attenuating EA illumination intensity enable accurate determinations of the electronic structures in these devices. We demonstrated that the electronic structures and the performance characteristics of multilayered polymer light-emitting diodes are also determined by the surface work functions of passivated metals. Our investigations confirm that electronic doping of the organic active layers, rather than minimisation of the Schottky barriers at electrode/polymer contacts, holds the key in realising high-performance organic light-emitting devices

Fractional Calculus and the Future of Science

Newton foresaw the limitations of geometry’s description of planetary behavior and developed fluxions (differentials) as the new language for celestial mechanics and as the way to implement his laws of mechanics. Two hundred years later Mandelbrot introduced the notion of fractals into the scientific lexicon of geometry, dynamics, and statistics and in so doing suggested ways to see beyond the limitations of Newton’s laws. Mandelbrot’s mathematical essays suggest how fractals may lead to the understanding of turbulence, viscoelasticity, and ultimately to end of dominance of the Newton’s macroscopic world view.Fractional Calculus and the Future of Science examines the nexus of these two game-changing contributions to our scientific understanding of the world. It addresses how non-integer differential equations replace Newton’s laws to describe the many guises of complexity, most of which lay beyond Newton’s experience, and many had even eluded Mandelbrot’s powerful intuition. The book’s authors look behind the mathematics and examine what must be true about a phenomenon’s behavior to justify the replacement of an integer-order with a noninteger-order (fractional) derivative. This window into the future of specific science disciplines using the fractional calculus lens suggests how what is seen entails a difference in scientific thinking and understanding