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This work develops optimal assembly sequences for modular building blocks. The underlying concept is that an automated device could take a virtual shape such as a CAD file, and automatically decide how to physically build the shape using simple, identical building blocks. This entails deciding where to place blocks inside the shape and generating an efficient assembly sequence that a robot could use to build the shape. The blocks are defined in a general, parameterized manner such that the model can be easily modified in the future. The primary focus of this work is the development of methods for generating assembly sequences in a time-feasible manner that ensure static stability at each step of the assembly. Most existing research focuses on complete enumeration of every possible assembly sequence and evaluation of many possible sequences. This, however, is not practical for systems with a large number of parts for two reasons: (1) the number of possible assembly sequences is exponential in the number of parts, and (2) each static stability test is very time-consuming. The approach proposed here is to develop a multi-hierarchical rule-based approach to assembly sequences. This is accomplished by formalizing and justifying both high-level and mid-level assembly rules based on static considerations. Application of these rules helps develop assembly sequences rapidly. The assembly sequence is developed in a time-feasible manner according to the geometry of the structure, rather than evaluating statics along the way. This work only evaluates the static stability of each step of the assembly once. The behavior of the various rules is observed both numerically and through theory, and guidelines are developed to suggest which rules to apply. A secondary focus of this work is to introduce methods by which the inside of the structure can be optimized. This structure optimization research is implemented by genetic algorithms that solve the multi-objective optimization problem in two dimensions, and can be extended to three dimensions.

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The readability of source code is essential for software maintenance. Since maintenance is an ongoing process, which is estimated to be 70 percent of the software development life cycle's total costs, it cannot be deprioritized. The readability of source code is likely to affect the program comprehension, which may help or create problems in the maintenance of the software. How different code features and functions affect the readability of source code have previously been investigated, and readability metrics have been developed. The project was initiated because of the lack of research on how programming knowledge and statically compared to dynamically typed programming languages affect the readability of the source code. A survey was conducted and included 21 computer science students with various programming knowledge, each rating eight code snippets, making it in total 168 ratings. The results showed that the type of programming language could improve the readability of source code. The results also showed that programming knowledge does not have a correlation with the ability to read source code.

[pt] A utilização de barras de polímero reforçado com fibra contínua (Fiber reinforced polymer, ou FRP) como reforço no concreto armado vem ganhando relevância no mercado devido às suas propriedades não corrosivas, alta resistência, durabilidade e transparência eletromagnética. Por outro lado, o comportamento frágil e o baixo módulo de elasticidade das barras de FRP limita sua aplicação e difusão no mercado da construção civil. Sob esta perspectiva, este trabalho avalia, em uma primeira etapa, o incremento de ductilidade em vigas de concreto armado com barras de GFRP (Glass fiber reinforced polymer) por meio da adição de fibras dispersas de vidro AR (álcali resistente) à matriz cimentícia e/ou pelo confinamento do concreto nas regiões críticas com o uso de estribos de GFRP. Para tal, são reportados e discutidos os resultados de ensaios realizados em oito vigas isostáticas sob flexão de quatro pontos, sendo quatro superarmadas e quatro são subarmadas. Em geral, as estratégias adotadas se mostraram bem-sucedidas apenas para as vigas superarmadas, que passaram a apresentar falhas caracterizadas por formação de cunha de compressão e grandes deslocamentos até a ruptura. Para avaliação da ductilidade, foram adotados dois métodos distintos: um baseado em energia (índice de ductilidade, (micro)E) e outro baseado em deformação (fator de performance, (micro)M). Para as vigas subarmadas, o fator de performance por meio da curvatura e o fator de performance por meio da deflexão representaram maiores incrementos de ductilidade para a viga com adição de fibras dispersas devido ao efeito do enrijecimento à tração, enquanto o índice de ductilidade não se mostrou uma boa alternativa para estas vigas. Para as vigas superarmadas, o fator de performance por meio da curvatura e o índice de ductilidade representaram maiores incrementos de ductilidade para as vigas com confinamento, enquanto no fator de performance por meio da deflexão, o incremento de ductilidade foi mais significativo para as vigas com adição de fibras. Em uma segunda etapa, é avaliada a capacidade de redistribuição de momentos fletores em três vigas hiperestáticas de dois vãos reforçadas com barras de GFRP contendo maior taxa de armadura inferior, bem como configurações distintas de armadura transversal e uso de fibras. Foi possível observar um aumento do momento nos centros dos vãos de 30 por cento e uma redução no momento no apoio central superior a 60 por cento, quando comparados aos momentos elásticos, que confirmam a influência da configuração da armadura na distribuição de esforços. / [en] The use of continuous fiber reinforced polymer (FRP) bars as an internal reinforcement for concrete has gained attention due to its non-corrosive properties, high resistance, requiring electromagnetic transparency. On the other hand, the brittle behavior and low modulus of elasticity of FRP bars limit their application and diffusion in the civil construction market. From this perspective, this work evaluates, firstly, the increase of ductility in GFRP (glass-fiber reinforced polymer) reinforced concrete beams by adding dispersed alkali-resistant (AR) glass fibers to the cementitious matrix and/or by confinement of the concrete in critical regions with the use of GFRP stirrups. To accomplish this task, the results of tests performed on eight statically determinate beams under four-point bending are reported and discussed, four of which are under-reinforced and four are over-reinforced. In general, the strategies adopted were successful only for the overreinforced beams, whose failures were characterized by the formation of a compression wedge and large displacements before rupture. For ductility evaluation, two distinct methods were adopted: one based on energy (ductility index, (micro)E) and another based on deformation (performance factor, (micro)M). For under-reinforced beams, the performance factor through curvature and the performance factor through deflection led to greater ductility increments for the beam with the addition of dispersed fibers due to the tensile stiffening effect, while the ductility index did not lead to good results. For the over-reinforced beams, the performance factor through curvature and the ductility index were able to describe the greater ductility increments for the confined beams, while the performance factor through deflection resulted in a greater ductility increment for the beams with discrete fiber addition. In a second step, the capacity of redistribution of moments in three statically indeterminate GFRP reinforced concrete beams with two spans and with a higher lower reinforcement ratio was evaluated for two different configurations of transverse reinforcement and for the use of fibers. It was possible to observe an increase in the positive moment of 30 percent (center of span) and a reduction in the negative moment (central support) greater than 60 percent, when compared to the elastic moments, confirming the influence of the reinforcement configuration on the distribution of internal forces.

Computer software is ubiquitous. More than 35 × 10 18 computer instructions are executed around the globe each second. As computers dominate more aspects of our lives, there is a growing need to reason more accurately about computer software. Most contemporary computer software is written using object-oriented (OO) programming languages, such as J AVA, C#, and C++. How should we mathematically characterize object-oriented software? This is the question this thesis addresses by presenting an accurate domain-theoretic model of mainstream object-oriented programming. Mainstream object-oriented languages are class-based. In such languages, the name of a class is part of the meaning of an object, a property often called "nominality". Most mainstream OO languages also conform to a static type discipline. Hence, the focus of this thesis is the construction of an accurate model of nominal, statically-typed OO languages. In statically-typed nominal OO languages, class names are also part of the meaning of corresponding class types, and class inheritance (subclassing) is explicitly declared; one class is a subclass of another only if it is declared as such. When static type systems are formulated to describe sets of objects, subtyping is defined so that subclassing is consistent with subtyping. Nevertheless, some programming languages (PL) theoreticians dismiss this identification as a design error because the only published models of OO languages exclude nominal information from objects and define subtyping in a way that ignores nominality. In nominal OO languages, program behavior depends on the nominal information embedded in objects. This thesis builds a model of OO languages called NOOP that includes nominal information and defines static types in accord with mainstream OO language designs. In NOOP , the meaning of every object includes its class name. Similarly, types are defined such that objects belong to a particular class type if and only if they are members of classes that inherit from the class corresponding to the class type. To demonstrate the utility of the model, we show that in NOOP inheritance and OO subtyping coincide. This work shows that mainstream OO languages are not technically defective in identifying inheritance and subtyping. In models that include nominal information and define types that respect nominal information, this identification is mathematically correct. The folklore among OO programming language researchers that "inheritance is not subtyping" is incorrect.

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As predicted by Gordon Moore, the number of transistors on a chip has roughly doubled every two years. Microprocessors featuring over a billion transistors are no longer science fiction. For example, Intel’s Itanium 9000 series and Intel’s Xeon 7400 series of processors feature 1.7 and 1.9 billion transistors respectively. To keep up with the emerging needs of contemporary very large scale integration (VLSI) design, industrial hardware description languages (HDLs) like Verilog and VHDL must be significantly enhanced. This thesis pinpoints some of the main shortcomings of the latest Verilog standard (IEEE 1364-2005) and shows how to overcome them by extending the language in a backward compatible way. To be able to cope with more complex circuits, well-understood higher-level abstraction mechanisms are needed. Verilog is already equipped with promising generative constructs making it possible to concisely describe a family of circuits as a parameterized module; however these constructs suffer from two problems: First, their expressivity is limited and second, they are not adequately supported by current tools. For instance, there are no static guarantees about the properties of the description generated as a result of instantiating a generic description with particular parameter values. Addressing both problems while remaining backward compatible led us to select a statically typed two-level languages (STTL) formal framework. By formalizing a core subset of Verilog as an STTL, we were able to define a static type system capable of: 1) checking the realizability of a description, 2) detecting bus width mismatches and array bounds violations, and 3) providing parametric guarantees on the resources required to realize a generic description. The power of the chosen framework is once more demonstrated as it also allows us to enrich the language with a new set of constructs that are designed to be expanded away when instantiated. To experiment with these ideas we implemented VPP, a Verilog Preprocessor with a built-in type checker. VPP is an unobtrusive tool accepting extended Verilog descriptions but generating descriptions compatible with any tool compliant with the Verilog standard. Our experience throughout this research showed that STTLs present a particularly suitable framework to formalize and implement generative features of a language. / Rice University, National Science Foundation (NSF) SoD award 0439017, Intel Corporation, Semiconductor Research Corporation (SRC) Task ID 1403.001

De nombreuses industries ont mené des recherches en vue de choisir la méthode appropriée afin d'améliorer les résultats, notamment Lean manufacturing et Six Sigma. Ce travail de thèse s’intéresse principalement à l’influence de l’implémentation de ces méthodes au sein des entreprises françaises, selon trois critères : financier, opérationnel et innovation. Les résultats de nos recherches montrent que les entreprises, appliquant Lean manufacturing et Six Sigma, sont plus efficacies pour l'amélioration des performances en matières financière et opérationnelle. Par ailleurs, les entreprises qui utilisent juste une partie des pratiques de Lean manufacturing et/ou de Six Sigma ont montré des améliorations limitées. En ce qui concerne le volet innovation, nous avons montré que l’implémentation de Lean manufacturing est suffisante pour avoir une amélioration des performances. En outre, nous avons constaté que les pratiques de Lean manufacturing et Six Sigma, telles que One Piece Flow, Kanban, 5S, etc. contribuent fortement à l’amélioration des performances. Les résultats statistiques montrent également que les facteurs clés, de la réussite de la mise en place de Lean et Six Sigma, peuvent être significativement différents selon la méthode. / Many industries conduct research in order to decide on the appropriate methodology for delivering optimal performance outcomes such as Lean Manufacturing or Six Sigma. Therefore, this research shows the influence of different categories based on the implementation method against three criteria: financial performance, operational performance and innovation performance. Research results indicate that companies implementing Lean Manufacturing and Six Sigma were more effective in improving company performance across financial and operational dynamics. Additionally, it shows companies who implemented Lean Manufacturing only saw improvements in innovation performance. Moreover, we found that Lean Manufacturing and Six Sigma practices such as One Piece Flow, Kanban, 5S, etc, supported increases in companies’ performance. The statistical results also show that the key factors for the success of Lean Manufacturing and Six Sigma implementation could differ depending on the method employed.