A New Characterization of Trivially Perfect Graphs

A graph $G$ is \emph{trivially perfect} if for every induced subgraph the cardinality of the largest set of pairwise nonadjacent vertices (the stability number) $\alpha(G)$ equals the number of (maximal) cliques $m(G)$. We characterize the trivially perfect graphs in terms of vertex-coloring and we extend some definitions to infinite graphs

World Modeling for Intelligent Autonomous Systems

The functioning of intelligent autonomous systems requires constant situation awareness and cognition analysis. Thus, it needs a memory structure that contains a description of the surrounding environment (world model) and serves as a central information hub. This book presents a row of theoretical and experimental results in the field of world modeling. This includes areas of dynamic and prior knowledge modeling, information fusion, management and qualitative/quantitative information analysis

World Modeling for Intelligent Autonomous Systems

The functioning of intelligent autonomous systems requires constant situation awareness and cognition analysis. Thus, it needs a memory structure that contains a description of the surrounding environment (world model) and serves as a central information hub. This book presents a row of theoretical and experimental results in the field of world modeling. This includes areas of dynamic and prior knowledge modeling, information fusion, management and qualitative/quantitative information analysis

MATHEMATICAL AND COMPUTER MODELING OF PROCESSES IN ELECTRIC CIRCUITS

Achievements in the computer engineering sphere leaded to appearance of many scientific and technical directions, among of which the direction of mathematical and computer modeling is emphasized. Modern technical devices of automation and informational measuring equipment are created on the base of this direction. The special software is designed to provide the solution of the different problems in this sphere. The future specialists must be able use the worked out application programs and expand these programs by own ones to reach the respective purposes. As a rule, the application packages have the module structure. For example, some numerical method of calculus mathematic may represent the module by the respective program (Newton’s method for the numerical solution of the system of nonlinear algebraic equations, Runge – Kutt’s method of the numerical solution of the system of the differential equations, the least – squares method, ets.)

World Modeling for Intelligent Autonomous Systems

Within the scope of this work, we have attained a row of theoretical and experimental results in the field of world modeling as well as gathered significant experience and expertise. The covered topics include concepts and approaches for dynamic and prior knowledge modeling, information association, fusion and management as well as their practical realization and experimental evaluation

Stable Spatial Solitons In Semiconductor Optical Amplifiers

A spatial soliton is a shape invariant self guided beam of light or a self induced waveguide. Spatial solitons appear as a result of the balance of diffraction and nonlinear focusing in a system. They have been observed in many different conservative media in the last couple of years. Solitons are ubiquitous, because of the probability of using their interactions in optical data processing, communications etc. Up to now due to the power required to generate the solitons, and the response times of the soliton supporting media, these special waves of nature could not penetrate the applications arena. Semiconductors, with their resonant nonlinearities, are thought to be ideal candidates for fast switching, low power spatial solitons. In this dissertation it is shown theoretically and experimentally that it is possible to observe stable spatial solitons in a periodically patterned semiconductor optical amplifier (PPSOA). The solitons have unique beam profiles that change only with system parameters, like pumping current, etc. Their coherent and incoherent interactions which could lead to all optical devices have been investigated experimentally and theoretically. The formation of filaments or modulational instability has been studied theoretically and yielded analytical formulae for evaluating the filament gain and the maximum spatial frequencies in PPSOA devices. Furthermore, discrete array amplifiers have been analyzed numerically for discrete solitons, and the prospect of using multi peak discrete solitons as laser amplifiers is discussed

An economic enquiry into the welfare effects of fair-trade

PhDThe copyright of this thesis rests with the author. Quotation from it is permitted, provided that full acknowledgement is made. This thesis may not be reproduced without the prior written consent of the author.Fair-trade is investigated at three levels. Each level relates to a specific group of actors. The first group are the consumers of fair-trade. In this respect fair-trade overlaps with altruism. A model is developed which seeks out parameters by which to judge whether or not a person will engage into this gesture of altruism, and accordingly measures the fair-trade utility of the consumer. On the basis that it is voluntary, fair-trade is deemed to be virtuous in that it either uplifts consumer utility, or else the consumer withdraws their patronage. Information is hypothesised to play a key role in determining the depth of this relationship. The second group are neighbouring producers, that is the non fair-trade producers who compete in the same market. A situation is modelled in which fair-trade is viewed as a switch in demand preference rather than new demand. The model allows an evaluation based on the standard tenets of welfare economics: to inform upon which movements are value-creating, which are merely transfers, the symmetry of those transfers and where Pareto improvements can and cannot be realised. The policymaker is afforded a logical overview, but with the implication that many of the relevant variables may be lie beyond their direct influence. The third group are landless vineyard labours in South Africa who are empirically analysised. We observed the strongest performance of fair-trade with respect to subjective improvement in wellbeing and the sort of participation that could be categorised as empowerment.Arts and Humanities Research Council (AHRC

Transient discharge of a pressurised incompressible fluid through a pipe and analytical solution for unsteady turbulent pipe flow

Programa Oficial de Doutoramento en Enxeñaría Naval e Industrial. 5015V01[Resumo] Estúdase a dinámica do proceso de descarga súbita dun líquido presurizado á atmosfera, de amplo interese en Enxeñaría de protección contra incendios. Preséntase o estado da arte respecto ao estudo do proceso de descarga. Elabórase un modelo hidráulico unidimensional para ese fluxo, que adopta a forma dunhas ecuacións intregro-diferenciais ordinarias que resólvense numéricamente. Efectúase unha análise de sensibilidade respecto a todos os parámetros dos que depende o modelo, con especial fincapé na fricción xerada pola turbulencia. Analizanse os métodos xenéricos de descrición da turbulencia, incluíndo a representación estatística, o filtrado de magnitudes turbulentas e a plena descrición analítica. Desenvólvese unha solución analítica xeral para o fluxo turbulento, incompresible e non estacionario nunha tubaxe. Elabórase un modelo computacional tridimensional para o fluxo descrito. A modelización da turbulencia resulta ser o punto mais importante e conflitivo de dito modelo. Compáranse os resultados obtidos con eles preditos polo modelo hidráulico unidimensional desenvolto previamente. Preséntanse resultados diso á estrutura interna da turbulencia en fluxos fortemente acelerados, prevéndose un aumento notable da devandita turbulencia nas proximidades do muro, que non se explica unicamente polo número de Reynolds.[Resumen] Se estudia la dinámica del proceso de descarga súbita de un líquido presurizado a la atmósfera, de amplio interés en Ingeniería de protección contra incendios. Se presenta el estado del arte en la literatura que trata dicho proceso de descarga. Se elabora un modelo hidráulico unidimensional para ese flujo, que adopta la forma de unas ecuaciones intregro-diferenciales ordinarias que se resuelven numéricamente. Se efectúa un análisis de sensibilidad respecto a todos los parámetros de los que depende el modelo, con especial hincapié en la fricción generada por la turbulencia. Se analizan los métodos genéricos de descripción de la turbulencia, incluyendo la representación estadística, el filtrado de magnitudes turbulentas y la plena descripción analítica. Se desarrolla una solución analítica general para el flujo turbulento, incompresible y no estacionario en un tubo. Se elabora un modelo computacional tridimensional para el flujo descrito. La modelización de la turbulencia resulta ser el punto más importante y conflictivo de dicho modelo. Se comparan los resultados obtenidos con los predichos por el modelo hidráulico unidimensional desarrollado previamente. Se presentan resultados respecto a la estructura interna de la turbulencia en flujos fuertemente acelerados, previéndose un aumento notable de dicha turbulencia en las proximidades de la pared, que no se explica únicamente por el número de Reynolds.[Abstract] The dynamics involved in the process of sudden discharge of a pressurized liquid to the atmosphere is studied, a case of broad interest in fire protection Engineering. The state of the art in the literature regarding such discharge process is presented. A one-dimensional hydraulic model is developed for this flow, which takes the form of ordinary intregro-di ferential equations that are solved numerically. A sensitivity analysis is carried out with respect to all the parameters on which the model depends, with special emphasis on the friction generated by the turbulence. The generic methods of describing turbulence are analysed, including the statistical representation, the filtering of turbulent quantities and the full analytical description. A general analytical solution for the turbulent, incompressible and unsteady flow in a pipe is developed. A three-dimensional computational model for the described flow is elaborated. The modelling of turbulence turns out to be the most important and conflicting point of such model. The results obtained are compared with those predicted by the one-dimensional hydraulic model previously developed. Results are presented regarding the internal structure of the turbulence in strongly accelerated flows. A remarkable increase of said turbulence is anticipated in the proximities of the wall, that could not be explained only with the Reynolds number