17 research outputs found
Fuzzy Mathematics
This book provides a timely overview of topics in fuzzy mathematics. It lays the foundation for further research and applications in a broad range of areas. It contains break-through analysis on how results from the many variations and extensions of fuzzy set theory can be obtained from known results of traditional fuzzy set theory. The book contains not only theoretical results, but a wide range of applications in areas such as decision analysis, optimal allocation in possibilistics and mixed models, pattern classification, credibility measures, algorithms for modeling uncertain data, and numerical methods for solving fuzzy linear systems. The book offers an excellent reference for advanced undergraduate and graduate students in applied and theoretical fuzzy mathematics. Researchers and referees in fuzzy set theory will find the book to be of extreme value
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Advanced controllers for building energy management systems. Advanced controllers based on traditional mathematical methods (MIMO P+I, state-space, adaptive solutions with constraints) and intelligent solutions (fuzzy logic and genetic algorithms) are investigated for humidifying, ventilating and air-conditioning applications.
This thesis presents the design and implementation of control strategies for building
energy management systems (BEMS). The controllers considered include the multi PI-loop controllers, state-space designs, constrained input and output MIMO adaptive
controllers, fuzzy logic solutions and genetic algorithm techniques. The control
performances of the designs developed using the various methods based on aspects such
as regulation errors squared, energy consumptions and the settling periods are
investigated for different designs. The aim of the control strategy is to regulate the room
temperature and the humidity to required comfort levels.
In this study the building system under study is a 3 input/ 2 output system subject to external disturbances/effects. The three inputs are heating, cooling and humidification,
and the 2 outputs are room air temperature and relative humidity. The external
disturbances consist of climatic effects and other stochastic influences. The study is
carried out within a simulation environment using the mathematical model of the test
room at Loughborough University and the designed control solutions are verified
through experimental trials using the full-scale BMS facility at the University of
Bradford
Power System Simulation, Control and Optimization
This Special Issue âPower System Simulation, Control and Optimizationâ offers valuable insights into the most recent research developments in these topics. The analysis, operation, and control of power systems are increasingly complex tasks that require advanced simulation models to analyze and control the effects of transformations concerning electricity grids today: Massive integration of renewable energies, progressive implementation of electric vehicles, development of intelligent networks, and progressive evolution of the applications of artificial intelligence
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Numerical issues and computational problems in algebraic control theory
The work of this thesis concerns computational issues arising from various fields of Algebraic Control Theory. Efficient algorithms covering the following classes of problems are developed.
(i) Exterior Algebra Computations: For given matrices [Please see formulas inside thesis] algorithms achieving the computation of [Please see formulas inside thesis] are formulated. An algorithm for the evaluation of Plucker matrices is also proposed. Most of these algorithms are used in the development of a unifying numerical algorithm for the solution of the Determinantal Assignment Problem.
(ii) Numerical Techniques for handling nonqeneric computations: Several numerical tools for the diagnosis of certain properties in an "almost sense", and the definition of procedures attaining the termination of algorithms are developed.
(iii) Evaluation of the Greatest Common Divisor of polynomials: A new numerical algorithm for the evaluation of the greatest common divisor of any set of polynomials is formulated.
(iv) Almost Zero Computations: Algorithms achieving the evaluation of the Prime almost zero of a polynomial set and the computation of the zero radius are given. Useful comments about the achievement of improved bounds for the zero-trapping region are also presented
Dynamic simulation of industrial grinding circuits : mineral liberation, advanced process control, and real-time optimisation
Ătant donnĂ© que les minĂ©raux apparaissent frĂ©quemment dans des associations complexes dans la nature, la libĂ©ration minĂ©rale est un aspect clĂ© du traitement de minerais et celle-ci est accomplie par comminution. Cette opĂ©ration est certainement lâune des plus importantes, mais aussi des plus coĂ»teuses dans lâindustrie. La rĂ©ussite globale dâune usine dĂ©pend souvent de la performance du circuit de broyage car il existe un compromis pour atteindre la taille des particules libĂ©rant les minĂ©raux ciblĂ©s afin dâobtenir des concentrĂ©s de haute puretĂ© tout en ayant de faibles coĂ»ts dâopĂ©ration, lesquels sont largement influencĂ©s par la consommation Ă©nergĂ©tique. Dans les annĂ©es rĂ©centes, les entreprises ont Ă©tĂ© confrontĂ©es Ă des objectifs de performance plus exigeants, une concurrence accrue sur les marchĂ©s, et des rĂ©glementations environnementales et de sĂ©curitĂ© plus strictes. Dâautres dĂ©fis supplĂ©mentaires sont inhĂ©rents aux circuits de broyage, par exemple les rĂ©ponses non linĂ©aires, le niveau Ă©levĂ© dâintercorrĂ©lation entre les variables et les recirculations de matiĂšre. Les problĂšmes ci-dessus soulignent la pertinence dâavoir des systĂšmes de contrĂŽle et dâoptimisation adĂ©quats pour lesquels les praticiens profitent de plus en plus des approches basĂ©es sur des modĂšles pour y faire face de façon systĂ©matique. La modĂ©lisation et la simulation sont des outils puissants ayant des avantages significatifs tels que les faibles coĂ»ts, les temps requis pour rĂ©aliser des expĂ©riences relativement courts et la possibilitĂ© de tester des conditions opĂ©rationnelles extrĂȘmes ainsi que diffĂ©rentes configurations des circuits sans interrompre la production. De toute Ă©vidence, la qualitĂ© des rĂ©sultats sera aussi bonne que la capacitĂ© du modĂšle Ă reprĂ©senter la rĂ©alitĂ©, ce qui souligne lâimportance dâavoir des modĂšles prĂ©cis et des procĂ©dures de calibrage appropriĂ©es, un sujet frĂ©quemment omis dans la littĂ©rature. Un autre aspect essentiel qui nâa pas Ă©tĂ© rapportĂ© est lâintĂ©gration efficace de la libĂ©ration minĂ©rale aux systĂšmes de contrĂŽle et dâoptimisation de procĂ©dĂ©s. Bien quâil sâagisse dâune information clĂ© directement liĂ©e aux performances de lâĂ©tape de concentration, la plupart des stratĂ©gies se concentrent exclusivement sur la taille de particule du produit. Ceci est comprĂ©hensible Ă©tant donnĂ© quâil est impossible de mesurer la distribution de libĂ©ration prĂ©sentement. BasĂ©e sur une librairie de simulation dâusines de traitement des minerais dĂ©jĂ existante, cette recherche aborde lesdits problĂšmes en (1) dĂ©veloppant un modĂšle de libĂ©ration minĂ©rale visant Ă coupler les Ă©tapes de broyage et de concentration ; (2) programmant et validant par calibrage un modĂšle phĂ©nomĂ©nologique de broyeur autogĂšne/semi-autogĂšne (BA/BSA), nĂ©cessaire pour complĂ©ter la librairie de simulation ; (3) couplant un simulateur de circuit de broyage Ă un procĂ©dĂ© de concentration avec le modĂšle de libĂ©ration, et (4) dĂ©veloppant un systĂšme de contrĂŽle et dâoptimisation qui considĂšre explicitement des donnĂ©es de libĂ©ration minĂ©rale pour Ă©valuer les avantages Ă©conomiques. Les principaux rĂ©sultats confirment que le modĂšle de libĂ©ration est capable de reproduire avec prĂ©cision des distributions de libĂ©ration minĂ©rale couramment observĂ©es dans lâindustrie. Cependant, si les donnĂ©es de calibrage correspondent Ă un point dâopĂ©ration unique, la validitĂ© pourrait ĂȘtre limitĂ©e aux rĂ©gions voisines proches. Le problĂšme de caractĂ©riser lâĂ©volution de la libĂ©ration minĂ©rale aux diverses conditions dâopĂ©ration ainsi quâaux rĂ©gimes transitoires reste Ă ĂȘtre abordĂ©. Le modĂšle de libĂ©ration sâest aussi rĂ©vĂ©lĂ© utile pour coupler des circuits de broyage avec des procĂ©dĂ©s de concentration, en particulier pour une unitĂ© de flottation. Quant au modĂšle de BA/BSA, celui-ci peut capturer le rĂ©gime statique ainsi que la dynamique dâun broyeur rĂ©el et conjointement avec le reste des Ă©quipements dans la librairie de simulation, des circuits de broyage industriels. Ceci a Ă©tĂ© confirmĂ© par le calibrage Ă partir des donnĂ©es dâopĂ©ration dâune usine et des tests en laboratoire, tout en suivant une procĂ©dure systĂ©matique, contribuant aussi au sujet de lâĂ©tablissement de mĂ©thodologies de calibrage standardisĂ©es. Pour terminer, les expĂ©riences concernant la stratĂ©gie de contrĂŽle et dâoptimisation basĂ©e sur la libĂ©ration minĂ©rale suggĂšrent que lâutilisation de cette information peut amĂ©liorer la performance globale des circuits de broyage-sĂ©paration en rĂ©agissant aux variations des caractĂ©ristiques de libĂ©ration, qui Ă leur tour influencent lâefficacitĂ© de sĂ©paration. LâĂ©tude de cas rĂ©alisĂ© rĂ©vĂšle que cela peut entraĂźner une augmentation du dĂ©bit massique et de la teneur du concentrĂ©, de la rĂ©cupĂ©ration des mĂ©taux et des revenus de lâordre de +0.5%, +1%, +1% et +5%, respectivement, par rapport au cas oĂč ces informations sont omises.As minerals frequently appear in complex associations in nature, mineral liberation is one of the most relevant aspects in ore processing and is achieved through comminution. This operation is one of the most important, but also one of the most expensive ones in industry. The global efficiency of a plant often depends on the performance of the grinding circuit, since there is a compromise to achieve the particle size liberating the targetted minerals in order to obtain high purity concentrates while maintaining low operating costs, which are largely influenced by the energy consumption. In recent years, companies have been facing more demanding performance targets, stronger competition, and more stringent environmental and safety regulations. Additional challenges are inherent to the grinding circuits themselves, e.g. the nonlinear responses, high degree of intercorrelation of the different variables, and material recirculations. The abovementioned issues highlight the relevance of adequate process control and optimisation, and practitioners rely more often on model-based approaches in order to face them systematically. Modeling and simulation are powerful tools with significant advantages such as low costs, required times for conducting experiments are relatively short, and the possibility of testing extreme operational conditions as well as different circuit configurations without disrupting production. Evidently, the quality of the results will only be as good as the model capacity to represent the reality, which emphasises the relevance of having precise models and proper calibration procedures, the latter being a topic frequently omitted in the literature. Another crucial aspect that has not been reported yet is the effective integration of mineral liberation in control and optimisation schemes. Although it is a key piece of information directly related to the performance of the concentration stage, most strategies focus exclusively on the particle size. This is understandable given that it is currently impossible to measure the liberation distribution online. Based on an existing mineral processing plant simulation library, this research addresses these problems by (1) developing a mineral liberation model aiming at linking the grinding and concentration stages; (2) programming a phenomenological autogenous/semiautogenous (AG/SAG) mill model, required to complement the simulation toolbox, and validating it through calibration; (3) coupling a grinding circuit simulator to a concentration process by means of the liberation model, and (4) developing a plantwide control and optimisation scheme considering mineral liberation data explicitly to evaluate the economic benefits. The main results confirm that the liberation model is capable of reproducing accurately mineral distributions observed in industry. If calibration data correspond to a single operating point, its validity may however be limited to the close neighbourhood. Characterising the evolution of mineral liberation in different operating conditions and transient states remains to be addressed. The liberation model proved to be equally useful in coupling grinding circuits with concentration processes, specifically for flotation. As for the AG/SAG mill model, it can capture the steady state and dynamic behaviour of an actual device and, along with the rest of pieces of equipment in the simulation toolbox, of industrial grinding circuits. This was confirmed through calibration from plant data and laboratory testwork following a systematic procedure, contributing to the endeavour of establishing standard calibration methodologies. Lastly, the results of the designed control and optimisation scheme suggest that using liberation data for control and real-time optimisation can improve the overall performance of grinding-separation circuits by reacting to variations in the liberation characteristics, which in turn influence the concentration performance. The case study reveals that doing so can lead to increases in the concentrate mass flow rate and grade, metal recovery, and global profits in the order of +0.5%, +1%, +1%, and +5%, respectively, compared to the case omitting this information
Error Bounds of Gaussian Quadratures for One Class of Bernstein-Szego Weight Functions
We consider the action of the automorphism group I(n) of Zn on the set
of kâsets of Zn in the natural way. Although elementary in its nature, it
has not been fully analyzed and understood yet. The vast class of enumerative and computational problems problems is related to this action. For
example, the number of orbits on the set of kâsets of Zn is one of them that
we are interested in. Those enumerative problems are mainly resolved by
application of P olya's theory