Hybrid systems now form a classical computational paradigm unifying discrete and continuous system aspects. The modelling, analysis and verification of these systems are very difficult. One way to reduce the complexity of hybrid system models is to consider randomization. The need for stochastic models has actually multiple motivations. Usually, when building models complete information is not available and we have to consider stochastic versions. Moreover, non-determinism and uncertainty are inherent to complex systems. The stochastic approach can be thought of as a way of quantifying non-determinism (by assigning a probability to each possible execution branch) and managing uncertainty. This is built upon to the - now classical - approach in algorithmics that provides polynomial complexity algorithms via randomization. In this thesis we investigate the stochastic hybrid systems, focused on modelling and analysis. We propose a powerful unifying paradigm that combines analytical and formal methods. Its applications vary from air traffic control to communication networks and healthcare systems. The stochastic hybrid system paradigm has an explosive development. This is because of its very powerful expressivity and the great variety of possible applications. Each hybrid system model can be randomized in different ways, giving rise to many classes of stochastic hybrid systems. Moreover, randomization can change profoundly the mathematical properties of discrete and continuous aspects and also can influence their interaction. Beyond the profound foundational and semantics issues, there is the possibility to combine and cross-fertilize techniques from analytic mathematics (like optimization, control, adaptivity, stability, existence and uniqueness of trajectories, sensitivity analysis) and formal methods (like bisimulation, specification, reachability analysis, model checking). These constitute the major motivations of our research. We investigate new models of stochastic hybrid systems and their associated problems. The main difference from the existing approaches is that we do not follow one way (based only on continuous or discrete mathematics), but their cross-fertilization. For stochastic hybrid systems we introduce concepts that have been defined only for discrete transition systems. Then, techniques that have been used in discrete automata now come in a new analytical fashion. This is partly explained by the fact that popular verification methods (like theorem proving) can hardly work even on probabilistic extensions of discrete systems. When the continuous dimension is added, the idea to use continuous mathematics methods for verification purposes comes in a natural way. The concrete contribution of this thesis has four major milestones: 1. A new and a very general model for stochastic hybrid systems; 2. Stochastic reachability for stochastic hybrid systems is introduced together with an approximating method to compute reach set probabilities; 3. Bisimulation for stochastic hybrid systems is introduced and relationship with reachability analysis is investigated. 4. Considering the communication issue, we extend the modelling paradigm.

No description available.

There is a lack of available technology to make small-scale power from biomass cost effectively. The proposed Hybrid Brayton cycle is an indirectly heated Brayton cycle with evaporative cooling for combined heat and power generation. It converts a direct fired microturbine to an indirectly heated power system. The Hybrid Brayton cycle offers a flexible biomass power generation platform in the 30 to 250 kWe range, achieving competitive efficiencies and advantages compared to other systems of similar power level. This cycle is designed to be implemented in remote and off-grids communities, small industries and net-zero communities, where local biomass feedstock is sustainably available. This proposed platform keeps operator qualifications to a minimum. In an effort to validate this new power cycle, a 30 kWe experimental facility was developed and initial commission phases performed. This facility purpose is to validate numerical model predictions and is used for optimization. The facility is described and results of the commissioning tests are reported with various problems encountered, solutions implemented and recommendations proposed. The thermodynamic model of the Hybrid Brayton cycle is also implemented in the MatLAB environment, incorporating experimental findings and new properties for humidified air at high temperatures. The MatLAB model confirms that an indirect fired Brayton cycle with evaporative cooling could be a viable approach for small scale distributed power generation using biomass. Additional experimental data of humidified air at elevated temperatures would provide more certainty in property predictions. The MatLAB model provides a modeling tool to allow resolving the issues identified during the commissioning of the test facility and offers alternatives to optimize various design configurations, implementing the most up to date property correlations for humidified air at elevated temperatures.

No description available.

This thesis examines hybrid novels – novels in which graphic devices like photographs, drawings and experimental typography are integrated into the written text. Within hybrid novels, word and image combine to create a text that is neither purely written, nor purely visual. Although not new, hybrid novels are increasingly appearing in commercial publishing, and increasingly recognised as an insufficiently explained phenomenon by both literary critics and academics. Book reviews and essays show that readers and critics accustomed to conventional novels can find hybrid novels perplexing. They ask: What are these images? What are they doing in novels? How does one ‘read’ them? These questions point to the need for new approaches to the analysis and critique of hybrid texts, approaches that account for the interplay between words and images. This thesis proposes that Visual Communication Designers – those versed in both the verbal and the visual – offer useful analytical tools and critique for the study of hybrid texts. So the research asks: How could a designer’s particular knowledge of wordimage interplay explain the function of graphic devices in hybrid novels? A preliminary study of fifteen hybrid novels develops: criteria for identifying hybrid novels; a typology of graphic devices in hybrid novels – photographs, illustrative elements, unconventional typesetting, ephemera and diagrams; and a set of analytical tools to critique the effectiveness of the graphic devices in hybrid novels. Then, a primary study uses the analytical tools to critique the graphic devices in three exemplar hybrid novels: Jonathan Safran Foer’s Extremely Loud and Incredibly Close, Steven Hall’s The Raw Shark Texts and Dave Egger’s You Shall Know Our Velocity. This thesis is practice-led in that an issue identified through my design practice led to the research, and analytical and critical tools derived from practice are applied as research methods. The research also draws upon a theoretical framework from the emergent field of Visual Studies, where scholars call for the interdisciplinary study of hybrid texts in a critically acute and widely accessible way. Finally, this thesis is itself a hybrid text; a combination of graphic devices and writing form parts of the argument.

This thesis examines hybrid novels – novels in which graphic devices like photographs, drawings and experimental typography are integrated into the written text. Within hybrid novels, word and image combine to create a text that is neither purely written, nor purely visual. Although not new, hybrid novels are increasingly appearing in commercial publishing, and increasingly recognised as an insufficiently explained phenomenon by both literary critics and academics. Book reviews and essays show that readers and critics accustomed to conventional novels can find hybrid novels perplexing. They ask: What are these images? What are they doing in novels? How does one ‘read’ them? These questions point to the need for new approaches to the analysis and critique of hybrid texts, approaches that account for the interplay between words and images. This thesis proposes that Visual Communication Designers – those versed in both the verbal and the visual – offer useful analytical tools and critique for the study of hybrid texts. So the research asks: How could a designer’s particular knowledge of wordimage interplay explain the function of graphic devices in hybrid novels? A preliminary study of fifteen hybrid novels develops: criteria for identifying hybrid novels; a typology of graphic devices in hybrid novels – photographs, illustrative elements, unconventional typesetting, ephemera and diagrams; and a set of analytical tools to critique the effectiveness of the graphic devices in hybrid novels. Then, a primary study uses the analytical tools to critique the graphic devices in three exemplar hybrid novels: Jonathan Safran Foer’s Extremely Loud and Incredibly Close, Steven Hall’s The Raw Shark Texts and Dave Egger’s You Shall Know Our Velocity. This thesis is practice-led in that an issue identified through my design practice led to the research, and analytical and critical tools derived from practice are applied as research methods. The research also draws upon a theoretical framework from the emergent field of Visual Studies, where scholars call for the interdisciplinary study of hybrid texts in a critically acute and widely accessible way. Finally, this thesis is itself a hybrid text; a combination of graphic devices and writing form parts of the argument.

Dissertation (Ph.D.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references.

Techn. Univ., Diss--München, 2004.

Ulm, Univ., Diss., 2008.

Thesis (Ph.D.)--George Mason University, 2008. / Vita: p. 163. Thesis director: Philip E. Auerswald. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Public Policy. Title from PDF t.p. (viewed June 30, 2008). Includes bibliographical references (p. 156-162). Also issued in print.