In recent years, many families have personal computers (PCs) and use the Internet service with high-speed modems. So providing high quality network services and connecting home devices together in a network are main i...
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Separating different aspects of a program, and encapsulating them inside well defined modules, is considered a good engineering discipline. this discipline is particularly desirable in the development of distributed a...
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ISBN:
(数字)9783540480464
ISBN:
(纸本)3540437843
Separating different aspects of a program, and encapsulating them inside well defined modules, is considered a good engineering discipline. this discipline is particularly desirable in the development of distributed agreement algorithms which are known to be difficult and error prone. For such algorithms, one aspect that is important to encapsulate is failure detection. In fact, a complete encapsulation was proven to be feasible in the context of distributed systems with process crash failures, by using black-box failure detectors. this paper discusses the feasibility of a similar encapsulation in the context of Byzantine (also called arbitrary or malicious) failures. We argue that, in the Byzantine context, it is just impossible to achieve the level of encapsulation of the original crash failure detector model. However, we also argue that there is some room for an intermediate approach where algorithms that solve agreement problems, such as consensus and atomic broadcast, can still benefit from grey-box failure detectors that partially encapsulate Byzantine failure detection.
the network-centric "system-of-systems" concept popular in current defense programs has been viewed from a very functional perspective. However, the heart of such a system is going to be an embedded software...
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ISBN:
(纸本)081944491X
the network-centric "system-of-systems" concept popular in current defense programs has been viewed from a very functional perspective. However, the heart of such a system is going to be an embedded software infrastructure of unprecedented complexity, and the technology for developing and testing this software needs as much if not more immediate attention than the concept of operations for the envisioned applications. Such an embedded software system will need to be infinitely scalable, modular, verifiable, and distributed, yet satisfy the myriad hard real-time performance constraints imposed by each of perhaps many different device types and service demands. It is suggested here that the only path to a robust design methodology for such systems is with model-based design. Model-based embedded system design is the focus of the Model-Based Integration of Embedded Software (MoBIES) program, currently underway at the Defense Advanced Research Projects Agency (DARPA), managed by the author. this paper will motivate the model-based approach to large-scale embedded software design and explain how projects funded under MoBIES are contributing to the development of interoperable model-based design tool components. An application for such technology is provided in the context of digital flight control systems for aggressive aircraft maneuvers, which is the subject of another DARPA sponsored program, Software-Enabled Control (SEC).
this paper proposes an environment intended for the development of fault-tolerant real-time Ada 95 applications conforming to the Ravenscar profile. this environment is based on the transparent replication of applicat...
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Cooperative robotic systems provide design and implementation challenges that are not easy to solve. this paper describes a parallel implementation for evolving cooperative robotic behaviour using an island model base...
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Cooperative robotic systems provide design and implementation challenges that are not easy to solve. this paper describes a parallel implementation for evolving cooperative robotic behaviour using an island model based genetic program on a cluster computer system. the application domain is robot soccer in which two robots must cooperate to avoid collisions with each other and score goals. the system has access to robot and ball positions and outputs velocity set points for the robot wheel motors. the evolved controllers are evaluated on a kinematic model that has been optimized to improve the time complexity of the genetic programming algorithm. the inter-process communication on the cluster is implemented using the message passing interface (MPI).
the kinematic constraints on a car limits the movements that it can follow, and this difficulty also makes planning a path a challenging problem. More precisely, the parallel parking problem has been widely addressed ...
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the kinematic constraints on a car limits the movements that it can follow, and this difficulty also makes planning a path a challenging problem. More precisely, the parallel parking problem has been widely addressed in the literature, but these approaches rely on more traditional methods using control laws, motion planners or artificial intelligence. there have been recently much interest in the robotics domain on using probabilistic approaches. In this paper, we propose an original formulation and resolution of the parking problem using Bayesian Robot programming.
the proceedings contain 84 papers. the special focus in this conference is on Principles and Practice of Constraint programming. the topics include: Hybrid benders decomposition algorithms in constraint logic programm...
ISBN:
(纸本)3540428631
the proceedings contain 84 papers. the special focus in this conference is on Principles and Practice of Constraint programming. the topics include: Hybrid benders decomposition algorithms in constraint logic programming;a hybrid framework integrating mixed integer programming and constraint logic programming;towards stochastic constraint programming;global cut framework for removing symmetries;capturing structure with satisfiability;phase transitions and backbones of 3-sat and maximum 3-sat;solving non-binary CSPS using the hidden variable encoding;a filtering algorithm for the stretch constraint;network flow problems in constraint programming;pruning for the minimum constraint family and for the number of distinct values constraint family;components for state restoration in tree search;constraint-based verification of client-server protocols;lower bounds for non-binary constraint optimization problems;a general scheme for multiple lower bound computation in constraint optimization;solving disjunctive constraints for interactive graphical applications;non-overlapping constraints between convex polytopes;formal models of heavy-tailed behavior in combinatorial search;in search of a phase transition in the ac-matching problem;a CLP approach to the protein side-chain placement problem;solving constraints over floating-point numbers;optimal pruning in parametric differential equations;an efficient filtering technique combining domain partition and arc consistency;the expressive power of binary linear programming;the traveling tournament problem description and benchmarks;structural constraint-based modeling and reasoning with basic configuration cells;solving Boolean satisfiability using local search guided by unit clause elimination and fast optimal instruction scheduling for single-issue processors with arbitrary latencies.
Traditionally reuse economics has by and large concentrated on return on investment in formal, systematic reuse based on traditional cost-benefit models. Of prime importance in that context was cost savings, and more ...
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ISBN:
(纸本)3540434836
Traditionally reuse economics has by and large concentrated on return on investment in formal, systematic reuse based on traditional cost-benefit models. Of prime importance in that context was cost savings, and more recently cost avoidance. Reuse was rationalized as a solution to minimizing wasteful consumption of resources through amortization of an artifact̵7;s development cost over multiple uses. the world has evolved since then. First, increased uncertainty in the software sector and technology in general have gradually shifted the focus from cost savings and cost avoidance to strategic issues of value generation, value management and risk. How does reuse create value in the context of strategic business decision-making? Second, the scope of reuse has evolved from type and class libraries to the entire architectural design process. Reuse economics is thus of prime concern when choosing among competing technologies and paradigms, and when applying them in a given context. How can our understanding of reuse economics leverage technical decision-making? third, the value of software today is determined to a considerable degree by external market forces. What impact does reuse have on market perception of software value? the goal of this workshop was to bring together interested practitioners and researchers to exchange ideas and experiences, discuss current and emerging practices, and introduce next-generation concepts.
Symmetric Multiprocessor (SMP) system and cluster of SMPs have become widely available as cost-effective parallel platforms. In this paper, the comparison of Motion Estimation (ME) algorithms implemented on SMP system...
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Symmetric Multiprocessor (SMP) system and cluster of SMPs have become widely available as cost-effective parallel platforms. In this paper, the comparison of Motion Estimation (ME) algorithms implemented on SMP system and cluster of SMPs was evaluated. the same parallel program written using MPI (Message-Passing Interface) programming model with different compilation procedures were implemented. Results show that the parallel ME algorithms scales well for SMP system (up to 6 processors) and cluster of SMPs (up to 23 processors). In terms of price/performance ratio, it is preferable to have a node with dual-processors than single-processor.
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