86 research outputs found

    An efficient optimal solution to the two-hoist no-wait cyclic scheduling problem

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    Hoist scheduling is a typical problem in the operation of electroplating systems. The cyclic scheduling policy is widely used in these systems in industry. Research on hoist scheduling has focused on the cyclic problem to minimize the cycle length. Most previous studies consider the single-hoist case. In practice, however, more than one hoist is often used in an electroplating line. This paper addresses the two-hoist, no-wait cyclic scheduling problem, in which the tank-processing times are constants and, upon completion of processing in a tank, the parts have to be moved to the next tank immediately. Based on the analysis of the problem properties, a polynomial algorithm is developed to obtain an optimal schedule. This algorithm first identifies a set of thresholds, which are special values of the cycle length, so that the feasibility property may change only at these thresholds. Feasibility checking is then carried out on each individual threshold in ascending order. The first feasible threshold found will be the optimal cycle length, and the corresponding feasible schedule is an optimal hoist schedule. © 2005 INFORMS

    Novel approaches to cyclic job-shop problems with transportation

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    Scheduling problems can be found in almost any field of application in the real world. These problems may not only have different characteristics but they also imply more or less complex requirements. One specific class within this domain is the cyclic job-shop problem. It occurs in various areas reaching from industrial production planning down to the systems architecture of computers. With manufacturers in particular, one can find increasing demand for effective solution methods in order to tackle these scheduling problems efficiently. This thesis will deal with the Cyclic Job-Shop Problem with Blocking and Transportation. It arises in modern manufacturing companies, where the products move automatically between the different workstations, for instance. The problem itself is not new to the research community, but hardly any work has been done in solving it. Within this thesis we will try to close this gap and present some first approaches, discussing the structure of the problem and how it can be solved. As a result, we will provide three different solution methods, including an integer programming formulation, which is solved with a commercial solver, a branch and bound algorithm and a tabu search heuristic. All algorithms are tested on a range of data sets and compared with each other. Additionally, we have worked on a polynomial solvable subproblem, which has gained more interest in the literature. As a result, a new polynomial algorithm, that outperforms the existing ones in theory as well as in empirical tests (except for some special cases) is presented. This thesis concludes with a discussion about ideas of how to improve the presented methods and some other extensions to the investigated problem

    Hybrid eager and lazy evaluation for efficient compilation of Haskell

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 208-220).This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.The advantage of a non-strict, purely functional language such as Haskell lies in its clean equational semantics. However, lazy implementations of Haskell fall short: they cannot express tail recursion gracefully without annotation. We describe resource-bounded hybrid evaluation, a mixture of strict and lazy evaluation, and its realization in Eager Haskell. From the programmer's perspective, Eager Haskell is simply another implementation of Haskell with the same clean equational semantics. Iteration can be expressed using tail recursion, without the need to resort to program annotations. Under hybrid evaluation, computations are ordinarily executed in program order just as in a strict functional language. When particular stack, heap, or time bounds are exceeded, suspensions are generated for all outstanding computations. These suspensions are re-started in a demand-driven fashion from the root. The Eager Haskell compiler translates Ac, the compiler's intermediate representation, to efficient C code. We use an equational semantics for Ac to develop simple correctness proofs for program transformations, and connect actions in the run-time system to steps in the hybrid evaluation strategy.(cont.) The focus of compilation is efficiency in the common case of straight-line execution; the handling of non-strictness and suspension are left to the run-time system. Several additional contributions have resulted from the implementation of hybrid evaluation. Eager Haskell is the first eager compiler to use a call stack. Our generational garbage collector uses this stack as an additional predictor of object lifetime. Objects above a stack watermark are assumed to be likely to die; we avoid promoting them. Those below are likely to remain untouched and therefore are good candidates for promotion. To avoid eagerly evaluating error checks, they are compiled into special bottom thunks, which are treated specially by the run-time system. The compiler identifies error handling code using a mixture of strictness and type information. This information is also used to avoid inlining error handlers, and to enable aggressive program transformation in the presence of error handling.by Jan-Willem Maessen.Ph.D

    English for Study and Work: Coursebook in 4 books. Book 2 Obtaining and Processing Information for Specific Purposes

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    Подано всі види діяльності студентів з вивчення англійської мови, спрямовані на розвиток мовної поведінки, необхідної для ефективного спілкування в академічному та професійному середовищах. Містить завдання і вправи, типові для різноманітних академічних та професійних сфер і ситуацій. Структура організації змісту – модульна, охоплює мовні знання і мовленнєві вміння залежно від мовної поведінки. Даний модуль має на меті розвиток у студентів стратегій, умінь, навичок читання, пошуку та вилучення професійно-орієнтованої інформації, необхідної для ефективної професійної діяльності і навчання. Містить завдання і вправи, типові для академічних та професійних сфер, пов’язаних з гірництвом і розробкою родовищ корисних копалин. Зразки текстів – автентичні, різножанрові, взяті з реального життя, містять цікаву й актуальну інформацію про особливості видобутку мінеральних ресурсів в провідних країнах світу, сучасний підхід до розробки родовищ тощо. Ресурси для самостійної роботи (Частина ІІ) містять завдання та вправи для розширення словникового запасу та розвитку знань найуживанішої термінології з гірництва, що спрямовано на організацію самостійної роботи з розвитку мовленнєвих умінь, знань про корисні копалини, методи їх видобутку. За допомогою засобів діагностики студенти можуть самостійно перевірити засвоєння навчального матеріалу й оцінити свої досягнення. Призначений для студентів вищих навчальних закладів, зокрема технічних університетів. Може використовуватися для самостійного вивчення англійської мови викладачами, фахівцями і науковцями різних галузей

    Complexity theory in axiomatic design

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.Includes bibliographical references (p. 177-182).During the last couple of decades, the term complexity has been commonly found in use in many fields of science, sometimes as a measurable quantity with a rigorous but narrow definition and other times as merely an ad hoc label. With an emphasis on pragmatic engineering applications, this thesis investigates the complexity concept defined in axiomatic design theory to avoid vague use of the term 'complexity' in engineering system design, to provide deeper insight into possible causes of complexity, and to develop a systematic approach to complexity reduction. The complexity concept in axiomatic design theory is defined as a measure of uncertainty in achieving a desired set of functional requirements. In this thesis, it is revisited to refine its definition. Four different types of complexity are identified in axiomatic design complexity theory: time-independent real complexity, time-independent imaginary complexity, time-dependent combinatorial complexity and time-dependent periodic complexity. Time-independent real complexity is equivalent to the information content, which is a measure of a probability of achieving functional requirements. Time-independent imaginary complexity is defined as the uncertainty due to ignorance of the interactions between functional requirements and design parameters. Time-dependent complexity consists of combinatorial complexity and periodic complexity, depending on whether the uncertainty increases indefinitely or occasionally stops increasing at certain point and returns to the initial level of uncertainty. In this thesis, existing definitions for each of the types of complexity are further elaborated with a focus on time-dependent complexity. In particular, time-dependent complexity is clearly defined using the concepts of time-varying system ranges and time-dependent sets of functional requirements.(cont.) Clear definition of the complexity concept that properly addresses the causes of complexity leads to a systematic approach for complexity reduction. As techniques for reducing time-independent complexity are known within and beyond axiomatic design theory, this thesis focuses on dealing with time-dependent complexity. From the definition of time-dependent complexity, combinatorial complexity must be transformed into periodic complexity to prevent the uncertainty from growing unboundedly. Time-dependence of complexity is attributed to two factors. One is a time-varying system range and the other is a time-dependent set of functional requirements. This thesis shows that achieving periodicity in time-varying system ranges and maintaining functional periodicity of time-dependent sets of functional requirements prevent a system from developing time-dependent combinatorial complexity. Following this argument, a re-initialization concept as a means to achieve and maintain periodicity is presented. Three examples are drawn from different fields, tribology, manufacturing system, and the cell biology, to support the periodicity argument and illustrate the re-initialization concept.by Taesik Lee.Ph.D

    OpenISA, um conjunto de instruções híbrido

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    Orientador: Edson BorinTese (doutorado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: OpenISA é concebido como a interface de processadores que pretendem ser altamente flexíveis. Isto é conseguido por meio de três estratégias: em primeiro lugar, o ISA é empiricamente escolhido para ser facilmente traduzido para outros, possibilitando flexibilidade do software no caso de um processador OpenISA físico não estar disponível. Neste caso, não há nenhuma necessidade de aplicar um processador virtual OpenISA em software. O ISA está preparado para ser estaticamente traduzido para outros ISAs. Segundo, o ISA não é um ISA concreto nem um ISA virtual, mas um híbrido com a capacidade de admitir modificações nos opcodes sem afetar a compatibilidade retroativa. Este mecanismo permite que as futuras versões do ISA possam sofrer modificações em vez de extensões simples das versões anteriores, um problema comum com ISA concretos, como o x86. Em terceiro lugar, a utilização de uma licença permissiva permite o ISA ser usado livremente por qualquer parte interessada no projeto. Nesta tese de doutorado, concentramo-nos nas instruções de nível de usuário do OpenISA. A tese discute (1) alternativas para ISAs, alternativas para distribuição de programas e o impacto de cada opção, (2) características importantes de OpenISA para atingir seus objetivos e (3) fornece uma completa avaliação do ISA escolhido com respeito a emulação de desempenho em duas CPUs populares, uma projetada pela Intel e outra pela ARM. Concluímos que a versão do OpenISA apresentada aqui pode preservar desempenho próximo do nativo quando traduzida para outros hospedeiros, funcionando como um modelo promissor para ISAs flexíveis da próxima geração que podem ser facilmente estendidos preservando a compatibilidade. Ainda, também mostramos como isso pode ser usado como um formato de distribuição de programas no nível de usuárioAbstract: OpenISA is designed as the interface of processors that aim to be highly flexible. This is achieved by means of three strategies: first, the ISA is empirically chosen to be easily translated to others, providing software flexibility in case a physical OpenISA processor is not available. Second, the ISA is not a concrete ISA nor a virtual ISA, but a hybrid one with the capability of admitting modifications to opcodes without impacting backwards compatibility. This mechanism allows future versions of the ISA to have real changes instead of simple extensions of previous versions, a common problem with concrete ISAs such as the x86. Third, the use of a permissive license allows the ISA to be freely used by any party interested in the project. In this PhD. thesis, we focus on the user-level instructions of OpenISA. The thesis discusses (1) ISA alternatives, program distribution alternatives and the impact of each choice, (2) important features of OpenISA to achieve its goals and (3) provides a thorough evaluation of the chosen ISA with respect to emulation performance on two popular host CPUs, one from Intel and another from ARM. We conclude that the version of OpenISA presented here can preserve close-to-native performance when translated to other hosts, working as a promising model for next-generation, flexible ISAs that can be easily extended while preserving backwards compatibility. Furthermore, we show how this can also be a program distribution format at user-levelDoutoradoCiência da ComputaçãoDoutor em Ciência da Computação2011/09630-1FAPES

    XVIII International Coal Preparation Congress

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    Changes in economic and market conditions of mineral raw materials in recent years have greatly increased demands on the ef fi ciency of mining production. This is certainly true of the coal industry. World coal consumption is growing faster than other types of fuel and in the past year it exceeded 7.6 billion tons. Coal extraction and processing technology are continuously evolving, becoming more economical and environmentally friendly. “ Clean coal ” technology is becoming increasingly popular. Coal chemistry, production of new materials and pharmacology are now added to the traditional use areas — power industry and metallurgy. The leading role in the development of new areas of coal use belongs to preparation technology and advanced coal processing. Hi-tech modern technology and the increasing interna- tional demand for its effectiveness and ef fi ciency put completely new goals for the University. Our main task is to develop a new generation of workforce capacity and research in line with global trends in the development of science and technology to address critical industry issues. Today Russia, like the rest of the world faces rapid and profound changes affecting all spheres of life. The de fi ning feature of modern era has been a rapid development of high technology, intellectual capital being its main asset and resource. The dynamics of scienti fi c and technological development requires acti- vation of University research activities. The University must be a generator of ideas to meet the needs of the economy and national development. Due to the high intellectual potential, University expert mission becomes more and more called for and is capable of providing professional assessment and building science-based predictions in various fi elds. Coal industry, as well as the whole fuel and energy sector of the global economy is growing fast. Global multinational energy companies are less likely to be under state in fl uence and will soon become the main mechanism for the rapid spread of technologies based on new knowledge. Mineral resources will have an even greater impact on the stability of the economies of many countries. Current progress in the technology of coal-based gas synthesis is not just a change in the traditional energy markets, but the emergence of new products of direct consumption, obtained from coal, such as synthetic fuels, chemicals and agrochemical products. All this requires a revision of the value of coal in the modern world economy

    Orbiting experiment for study of extended weightlessness Final report

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    Design, mission, and development of orbiting experiment to study extended weightlessness using monkeys and Apollo applications vehicl
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