In this paper we present a computational method to generate a network of vessels by optimization of its individual bifurcations and topology in such a way, that the local (geometric) and global (topological) structure...
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In this paper we present a computational method to generate a network of vessels by optimization of its individual bifurcations and topology in such a way, that the local (geometric) and global (topological) structure of the vessel tree is optimized according to the same target function. Arterial trees are modeled as two-dimensional branching systems of straight cylindrical tubes. Resistance and flow conditions in the model trees are governed by Poiseuille's law. Tree generation is performed by successively adding segments, so that certain structural and geometric constraints are fulfilled at each stage of development. In the present work, the structural characteristics of trees with 4000 terminal segments generated by constrained constructive optimization (CCO) are investigated and related to variation of the constraints, the optimization criteria, and the sequence in which new terminal segments are added to the tree. (C) 1997 Elsevier Science Ltd.
the Logic Assurance System (LA) combines testing, debugging, monitoring and control of real-time systems. It is capable of improving system's reliability and development productivity. this is achieved by enabling ...
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the Logic Assurance System (LA) combines testing, debugging, monitoring and control of real-time systems. It is capable of improving system's reliability and development productivity. this is achieved by enabling the developer to describe parts of the specification with logic and temporal logic assertions. the assertions, which are written in the LA Language and describe parts of the specification, are automatically compared to the actual behavior of the system under development (SUD) and its environment. Information about the SUD's behavior is represented by informative events and states. this information is transferred to LA from different resources, including from inside the tested software, by using special directives inserted inside the code (an approach we call informative box). When an assertion is violated, an informative message is given so that bugs can be detected and focused on. In addition to the message, a user function can be called. this can be used for real-time control and monitoring either while testing the system or after it has already been launched (for example, when testing assertions regarding safety). the informative box method enables one to perform smart, pin-pointed tests and temporal tests, neither of which can be performed by using standard black-box techniques. this is why LA can assist in the testing and integration of real-time embedded systems, reactive systems, and particular, in the testing of multiprocessor systems running cooperative processes. It is anticipated that considerable time and effort can be saved by using LA throughout the development process. Moreover, it has the capability to detect erroneous situations that otherwise would be more difficult to notice, as was proven when used to handle several communication protocol simulations.
the proceedings contains 74 papers from the 30th Annual Hawaii International conference on systems Sciences. Topics discussed include: complex computersystems;Monash secure reduced instruction set computing (RISC) mu...
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the proceedings contains 74 papers from the 30th Annual Hawaii International conference on systems Sciences. Topics discussed include: complex computersystems;Monash secure reduced instruction set computing (RISC) multiprocessor;distributed multimedia;asynchronous transfer mode (ATM) network;multimedia communications;software maintenance environment;multi-procedure program dynamic decomposition;data-intensive business programs;genetic algorithms;global system for mobile communications cellular network;mobile ATM networks;adaptive video on demand;data-driven reconfigurable accelerators;nuclear power plant's process automation system;complex embedded systems;and virtual memory management systems.
We describe the application of model checking tools to analyze a real-time software challenge in the design of Lucent Technologies' 5ESS telephone switching system. We use two tools: COSPAN for checking real-time ...
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ISBN:
(纸本)0897919149
We describe the application of model checking tools to analyze a real-time software challenge in the design of Lucent Technologies' 5ESS telephone switching system. We use two tools: COSPAN for checking real-time properties, and TPWB for checking probabilistic specifications. We report on the feedback given by the tools, and based on our experience, discuss the advantages and the limitations of the approach used.
this report describes the adoption of Cleanroom softwareengineering Methodology into a mature software organization as defined by the SEI's Capability Maturity Model. the organization, a defense contractor operat...
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ISBN:
(纸本)0897919149
this report describes the adoption of Cleanroom softwareengineering Methodology into a mature software organization as defined by the SEI's Capability Maturity Model. the organization, a defense contractor operating at SEI Level 4/5, has been working to develop a large real time system under tight budget and schedule constraints. this overview describes how Cleanroom principles were incorporated into an existing, mature software development framework and outlines some of the techniques used to facilitate the transition from a conventional to a Cleanroom development effort. In addition, we also describe issues related to impact and technology insertion.
three naming strategies are discussed that allow the processes of a distributed application to continue being addressed by their original logical name, along all the migrations they may be forced to undertake because ...
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three naming strategies are discussed that allow the processes of a distributed application to continue being addressed by their original logical name, along all the migrations they may be forced to undertake because of performance-improvement goals. A simple centralised solution is firstly discussed which showed a software bottleneck withthe increase of the number of processes;other two solutions are considered that entail different communication schemes and different communication overheads for the naming protocol. All these strategies are based on the facility that each process is allowed to survive after migration, even in its original site, only to provide a forwarding service to those communications that used its obsolete address. the adopted strategies are designed to reduce the process survival time, and at the same time, to be safe and simple, so as to entail an overhead as low as possible. Such performance objectives are evaluated making the three strategies work withthe same testing application.
In this paper we outline a semantic model for open distributed systems which provides a foundation for a corresponding architecture description language. this Semantic model is based on architecture models reported in...
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ISBN:
(纸本)0818677430
In this paper we outline a semantic model for open distributed systems which provides a foundation for a corresponding architecture description language. this Semantic model is based on architecture models reported in [2][5] with a number of refinements to support abstraction and composition. the model is specifically designed to describe open distributed systems independent Of implementation details such as communication protocols and middleware systems. the modelling concepts in the semantic model are: Object (a model of an entity), event (a unit of interaction between an object and its environment), event relationship (a specification of behaviour defining the relationships amongst a set of events), interface tan abstraction of an object's interaction with its environment) and binding (a context for interaction between objects). the binding concept is particularly important because it can describe any kind of interaction in an open distributed system, ranging from remote procedure calls and multicast to more complex, enterprise interactions. Special attention is given to the problem of composition and abstraction of events and behaviour in the model. this is needed to reflect the reuse, evolution and interworking requirements of open distributed systems. Our approach allows for the effective modelling of asynchrony, concurrency and complex flaws of information in open distributed systems.
We show how to use recursive function theory to prove Turing universality of finite analog recurrent neural nets, with a piecewise linear sigmoid function as activation function. We emphasize the modular construction ...
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Dynamically composed softwaresystems are constructed as they execute. Although these systems are of increasing importance and arise in a number of application areas, configuration management tools typically do not pr...
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