Jürgen Sprekels – författare

In this regard, we refer to the works of Pironneau [1984], Haslinger and Neittaanmaki [1988], [1996], Sokolowski and Zolksio [1992], Litvinov [2000], Allaire [2001], Mohammadi and Pironneau [2001], Delfour and Zolksio [2001], and Makinen and Haslinger [2003].

This book presents a mathematical analysis of hysteretic phenomena, where two complementary viewpoints are taken: at first, scalar rate independent hysteresis is studied in a general setting that is based on the interplay between a discrete diagram-oriented and a function space approach: later, the connections between the occurrence of hysteresis and physical mechanisms like energy dissipation and phase transitions are discussed. The exposition ranges from the thermodynamic foundation of phenomenological theories of phase transitions over the variational formulation of the resulting initial-boundary value problems to the rigorous proof of results concerning existence, uniqueness and numerical approximation.

This monograph provides a comprehensive and accessible introduction to the optimization of elliptic systems. This area of mathematical research, which has many important application in science and technology, has experienced an impressive development during the last two decades. This monograph aims to address some of the pressing unsolved questions in the field. The exposition concentrates along two main directions: the optimal control of linear and nonlinear elliptic equations, and problems involving unknown and/or variable domains. Throughout this monograph, the authors elucidate connections between seemingly different types of problems. One basic feature is to relax the needed regularity assumptions as much as possible in order to include larger classes of possible applications. The book is organized into six chapters that give a gradual and accessible presentation of the material, and a special effort is made to present numerous examples. This monograph is addressed to a large readership, primarily to graduate students and researchers working in this field of mathematics.Much of this material will prove useful also for scientists from other fields where the optimization of elliptic systems occurs, such as physics, mechanics, and engineering.

Hysteresis is an exciting and mathematically challenging phenomenon that oc­ curs in rather different situations: jt, can be a byproduct offundamental physical mechanisms (such as phase transitions) or the consequence of a degradation or imperfection (like the play in a mechanical system), or it is built deliberately into a system in order to monitor its behaviour, as in the case of the heat control via thermostats. The delicate interplay between memory effects and the occurrence of hys­ teresis loops has the effect that hysteresis is a genuinely nonlinear phenomenon which is usually non-smooth and thus not easy to treat mathematically. Hence it was only in the early seventies that the group of Russian scientists around M. A. Krasnoselskii initiated a systematic mathematical investigation of the phenomenon of hysteresis which culminated in the fundamental monograph Krasnoselskii-Pokrovskii (1983). In the meantime, many mathematicians have contributed to the mathematical theory, and the important monographs of 1. Mayergoyz (1991) and A. Visintin (1994a) have appeared. We came into contact with the notion of hysteresis around the year 1980.

This volume gathers contributions in the field of partial differential equations, with a focus on mathematical models in phase transitions, complex fluids and thermomechanics. These contributions are dedicated to Professor Gianni Gilardi on the occasion of his 70th birthday. It particularly develops the following thematic areas: nonlinear dynamic and stationary equations; well-posedness of initial and boundary value problems for systems of PDEs; regularity properties for the solutions; optimal control problems and optimality conditions; feedback stabilization and stability results. Most of the articles are presented in a self-contained manner, and describe new achievements and/or the state of the art in their line of research, providing interested readers with an overview of recent advances and future research directions in PDEs.

This volume gathers contributions in the field of partial differential equations, with a focus on mathematical models in phase transitions, complex fluids and thermomechanics.

Der Berliner Mathematiker Karl Weierstraß (1815-1897) lieferte grundlegende Beiträge zu den mathematischen Fachgebieten der Funktionentheorie, Algebra und Variationsrechnung. Er gilt weltweit als Begründer der mathematisch strengen Beweisführung in der Analysis. Mit seinem Namen verbunden ist zum Beispiel die berühmte Epsilon-Delta-Definition des Begriffs der Stetigkeit reeller Funktionen. Weierstraß’ Vorlesungszyklus zur Analysis in Berlin wurde weithin gerühmt und er lehrte teilweise vor 250 Hörern aus ganz Europa; diese starke mathematische Schule prägt bis heute die Mathematik. Aus Anlass seines 200. Geburtstags am 31. Oktober 2015 haben internationale Experten der Mathematik und Mathematikgeschichte diesen Festband zusammengestellt, der einen Einblick in die Bedeutung von Weierstraß’ Werk bis zur heutigen Zeit gibt.Die Herausgeber des Buches sind leitende Wissenschaftler am Weierstraß-Institut für Angewandte Analysis und Stochastik in Berlin, die Autoren eminente Mathematikhistoriker.

Interest in the area of control of systems defined by partial differential Equations has increased strongly in recent years. A major reason has been the requirement of these systems for sensible continuum mechanical modelling and optimization or control techniques which account for typical physical phenomena. Particular examples of problems on which substantial progress has been made are the control and stabilization of mechatronic structures, the control of growth of thin films and crystals, the control of Laser and semi-conductor devices, and shape optimization problems for turbomachine blades, shells, smart materials and microdiffractive optics. This volume contains original articles by world reknowned experts in the fields of optimal control of partial differential equations, shape optimization, numerical methods for partial differential equations and fluid dynamics, all of whom have contributed to the analysis and solution of many of the problems discussed. The collection provides a state-of-the-art overview of the most challenging and exciting recent developments in the field.It is geared towards postgraduate students and researchers dealing with the theoretical and practical aspects of a wide variety of high technology problems in applied mathematics, fluid control, optimal design, and computer modelling.

The international Conference on Optimal Control of Coupled Systems of Partial Di?erential Equations was held at the Mathematisches Forschungsinstitut Ob- wolfach (www.mfo.de) from April, 17 to 23, 2005. The scienti?c program included 30 talks coveringvarious topics as controllability,feedback-control,optimality s- tems, model-reduction techniques, analysis and optimal control of ?ow problems and ?uid-structure interactions, as well as problems of shape and topology op- mization. The applications discussed during the conference range from the op- mization and control of quantum mechanical systems, the design of piezo-electric acoustic micro-mechanical devices, optimal control of crystal growth, the control of bodies immersed into a ?uid to airfoil design and much more. Thus the app- cations are across all time and length scales. Optimization and control of systems governed by partial di?erential eq- tions and more recently by variational inequalities is a very active ?eld of research in Applied Mathematics, in particular in numerical analysis, scienti?c comp- ing and optimization.In order to able to handle real-world applications, scalable and parallelizable algorithms have to be designed, implemented and validated. This requires an in-depth understanding of both the theoretical properties and the numerical realization of such structural insights. Therefore, a 'core' devel- ment within the ?eld of optimization with PDE-constraints such as the analysis of control-and-state-constrained problems, the role of obstacles, multi-phases etc. and an interdisciplinary 'diagonal' bridging regarding applications and numerical simulation are most important.

The articles contained in this volume are related to presentations at the inter- tional "Conference on Optimal Control of Coupled Systems of Partial Di?erential Equations", held at the "Mathematisches Forschungsinstitut Oberwolfach" from March, 2 to 8, 2008. The contributions by internationally well-known scientists in the ?eld of Applied Mathematics cover various topics as controllability, feedba- control,optimalitysystems,model-reductiontechniques,analysisandoptimalc- trol of ?ow problems and ?uid-structure interactions, as well as problems of shape and topology optimization. The applications considered range from the optimi- tion and control of quantum mechanical systems, the optimal design of airfoils, optimal control of crystal growth, the optimization of shape and topology in en- neering to switching or hybrid systems. The applications are thus across all time and length scales, and range from smooth to non-smooth models. The ?eld of optimization and control of systems governed by partial d- ferential equations and variational inequalities is a very active area of research in Applied Mathematics and in particular in numerical analysis, scienti?c c- puting and optimization with a growing impact on engineering applications.In return, the ?eld bene?ts from fascinating and challenging applications in that new mathematical often multiscale-modeling and new numerical tools as well as novel optimization results and corresponding iterative strategies arerequired in order to handle these problems. In particular,it becomes amply clear that constraints have to be taken into account, both on the control- and design-variables as well as on the state variablesandthe domains oftheir governingmodels.

This book is a compilation of high quality papers focussing on five major areas of active development in the wide field of differential equations: dynamical systems, infinite dimensions, global attractors and stability, computational aspects, and applications. It is a valuable reference for researchers in diverse disciplines, ranging from mathematics through physics, engineering, chemistry, nonlinear science to the life sciences.