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8.6.2 Maintainability Considerations for Software Intensive systems

INCOSE International Symposium 2004年第1期14卷 1797-1809页

作者： Ramchand, Ramya Tatikonda, Nirmala Verma, Dinesh Nance, Richard E. System Integration Laboratory Stevens Institute of Technology HobokenNJ07030 United States Systems Research Center Virginia Tech BlacksburgVA24060 United States Dept. of Systems Engineering & Engg. Mgmt Stevens Institute of Technology HobokenNJ07030 United States Dept. of Computer Science Virginia Tech BlacksburgVA24060 United States

This paper reflects one aspect of an overall research initiative to better understand and articulate the "cause and effect" relationship between design causes and operational effects. Here the specific focus is on "before the fact" system maintainability. Maintenance considerations for software intensive systems must be addressed early in design and must focus on the entire system life cycle. Use of commercial-off-the-shelf (COTS) components in system architectures reinforces this need. COTS usage can be readily observed in modern commercial and defense systems. Such architectures are often characterized by an evolving physical baseline (technology refreshment) driven by obsolescence considerations. This paper proposes aspects of a framework to evaluate system architectures, with a particular focus on system maintainability and with the objective of positively influencing the long-term cost of operational maintenance. © 2004 The Authors.

关键词： Maintainability

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8.6.3 Maintenance Practices and Metrics across Defense and Commercial systems

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INCOSE International Symposium 2004年第1期14卷 1810-1820页

systems and software engineering are converging disciplines with increasing evolution of modern complex systems towards increased information and knowledge content. Further, with the capital investment associated with such systems and their long operational life spans, a longer-term notion of quality during design and implementation is necessary. The realities of cost, safety, and staffing considerations are forcing increasing emphasis on reuse and reengineering strategies. This imperative becomes even more urgent with the thrust towards the inclusion of commercial-off-the-shelf components in system architectures. One key operational imperative for complex systems is the cost of maintenance. This paper presents an industry survey conducted to understand maintenance practices prevalent in commercial and defense industries. Results from an industry survey focused on system maintenance measures and metrics are also presented. This survey focused on information and knowledge intensive systems and was supported by INCOSE-The International Council on systems Engineering and SOLE-The International Society of Logistics. © 2004 The Authors.

关键词： Investments

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Preface

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Lecture Notes in computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2004年 3222卷 v-vi页

作者： Siegel, H.J. Li, Guojie Ebcioglu, Kemal Gao, Guang R. Xu, Zhiwei University of Delaware Computer Architecture and Parallel System Laboratory 140 Evans Hall NewarkDE United States Chinese Academy of Sciences Institute of Computing Technology P.O. Box 2704 Beijing China

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SROAM: an end-to-end service model for improved performance in roaming over wireless LAN networks

SROAM: an end-to-end service model for improved performance ...

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International Conference on computer Networks and Mobile Computing (ICCNMC)

作者： Jun Yuan Chao Liu Xiaoming Li Computer Networks and Distributed System Laboratory Department of Computer Science and Technology Computer Networks and Distrubed System Laboratory Peking University China

ISBN: (纸本)0769520332

Nowadays mobile devices enable users to have various ways to surf on the Internet and broadband communication channels facilitate applications of online multimedia. Most network real-time multimedia applications run on TCP/IP protocol stack. Although several protocols are proposed to handle mobility management on the network layer, real-time stream transmission still suffers from severe roaming interruption and hence playback performance is worsened. The paper analyzes the roaming delay and transmission throughput in detail and evaluates the effect of multiple elements constituting the whole roaming delay. A service codenamed Swift Roaming system (SROAM) is proposed to reduce the roaming delay and increase the average transmission throughput. Some initial experiment results are provided to support the effectiveness of the methods proposed in the system.

关键词： Roaming Wireless LAN Streaming media Protocols Delay effects Throughput Internet Broadband communication Communication channels TCPIP

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A network service framework for mobile pervasive computing

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International Conference on Communication technology (ICCT)

作者： Enyi Chen Yuanchun Shi Guangyou Xu Department of Computer Science and Technology The State Key Laboratory on Intelligence System and Technology Tsinghua University Beijing China

ISBN: (纸本)7563506861

In this paper, we propose a framework for wireless/mobile pervasive computing to augment capabilities and to save scanty resources of mobile host by making full use of available resources in the surrounding. Firstly, a mobile device finds and utilizes the cheap computer as a surrogate to forward the service requests. Secondly, after the surrogate discovers the services, it will filter, synthesize or handoff them according to the context information. We also take consideration of robustness, scalability, and load balancing by utilizing multi surrogates. Service descriptions are encoded by the extensible markup language (XML) technology to provide flexibility. The analytical results on the performance of our framework show that it has significant advantages in terms of reducing wireless bandwidth consumption, ant etc.

关键词： Mobile computing Pervasive computing XML Information filtering Information filters Context-aware services Robustness Scalability Load management Performance analysis

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Seamless provisioning of service in the ubiquitous computing environment

Seamless provisioning of service in the ubiquitous computing...

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International Conference on Machine Learning and Cybernetics (ICMLC)

作者： En-Yi Chen De-Gan Zhang Yuan-Chun Shi Guang-You Xu The State Key Laboratory of Intelligence System and Technology Department of Computer Science and Technology Tsinghua University Beijing China

ISBN: (纸本)0780378652

In the ubiquitous computing environment (UCE), how to seamlessly provision the service or application to its occupant or its mobile user is an interesting research topic. This paper introduces our two UCEs called smart classroom (SCR) and intelligent meeting room (IMR) respectively. When a teacher gives his lesson in the SCR, different services will automatically be provisioned to him according to captured context information. When the users with various kinds of portable devices, such as PDA, mobile phone or laptop, attend a meeting in IMR, they can easily organize a meeting and unobtrusively access the services provided by IMR, for example, they could give presentation by "projector service". The paper also describes the software infrastructure of SCR and IMR - smart platform, a multi agents (MAs) system.

关键词： Ubiquitous computing Pervasive computing Thyristors Portable computers Application software Mobile computing Embedded software computer networks Space technology Education

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Parameter optimization for information retrieval with genetic algorithm

Parameter optimization for information retrieval with geneti...

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IEEE International Conference on systems, Man and Cybernetics

作者： Chuan Lin Shao-ping Ma Min Zhang State Key laboratory of Intelligent Technology and System Department of Computer TechnologyScience and Tsinghua University China

ISBN: (纸本)0780379527

In most of the modern information retrieval (IR) systems, such as Okapi system, there are a variety of parameters to be turned which are data-dependent and sensitive. Manual parameter setting with fixed experimental values is not always feasible and reliable in practical cases. Furthermore, the supervised learning approaches are not applicable for lacking of relevant information while retrieving. Therefore, an automatic unsupervised parameter learning mechanism is necessary and important. In this paper, a genetic algorithm (GA) based parameter optimization approach is proposed and experimented on Okapi system using large scale data sets of TREC11, TREC10 and TREC9 web track collections. It indicates that our algorithm is effective to adjust system parameters and improve the retrieval performance significantly.

关键词： Information retrieval Genetic algorithms computer science Laboratories Training data Intelligent systems Modems Large-scale systems computer hacking Optical computing

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Algorithms for nonuniform bandpass sampling in radio receiver

Algorithms for nonuniform bandpass sampling in radio receive...

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IEEE International Symposium on Circuits and systems (ISCAS)

作者： Yi-Ran Sun S. Signell Laboratory of Electronics and Computer System (LECS) Institute of Microelectronics and Information Technology (IMIT) Royal Institute of Technology Stockholm Sweden

The bandpass sampling (BPS) technique enables one to have an interface between IF stage and ADC in a radio receiver. Nonuniform BPS has the potential to suppress aliasing without care about the information band position of a modulated signal. However, a signal cannot be reconstructed from its nonuniform samples by using only an ideal lowpass filter. In this paper, a filter is generalized to a reconstruction algorithm (RA). Six different algorithms for reconstructing a signal from its nonuniform samples are summarized. A general reconstruction formula in terms of a basis-kernel (BK) function is used to describe the algorithms. Finally, with regard to the application to radio communications, accuracy of reconstruction, computational complexity and hardware implementation are shown and compared for these algorithms.

关键词： Sampling methods Receivers Image reconstruction RF signals Hardware Radio communication Computational complexity Bandwidth Low pass filters Interpolation

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Dynamic scheduling issues in SMT architectures

Dynamic scheduling issues in SMT architectures

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International Parallel and Distributed Processing Symposium, IPDPS 2003

作者： Shin, Chulho Lee, Seong-Won Gaudiot, Jean-Luc System Design Technology Laboratory Samsung Electronics Corporation Korea Republic of Dept. of Electrical Engineering - Systems University of Southern California United States Dept. of Electrical Engineering and Computer Science University of California Irvine United States

ISBN: (纸本)0769519261

Simultaneous multithreading (SMT) attempts to attain higher processor utilization by allowing instructions from multiple independent threads to coexist in a processor and compete for shared resources. Previous studies have shown, however, that its throughput may be limited by the number of threads. A reason is that a fixed thread scheduling policy cannot be optimal for the varying mixes of threads it may face in an SMT processor. Our adaptive dynamic thread scheduling (ADTS) was previously proposed to achieve higher utilization by allowing a detector thread to make use of wasted pipeline slots with nominal hardware and software costs. The detector thread adaptively switches between various fetch policies. Our previous study showed that a single fixed thread scheduling policy presents much room (some 30%) for improvement compared to an oracle-scheduled case. In this paper, we take a closer look at ADTS. We implemented the functional model of the ADTS and its software architecture to evaluate various heuristics for determining a better fetch policy for a next scheduling quantum. We report that performance could be improved by as much as 25%. © 2003 IEEE.

关键词： Scheduling

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A new and practical approach to secure mobile agent server development

A new and practical approach to secure mobile agent server d...

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IEEE Conference on Wireless Communications and Networking

作者： M.R. Razzazi J. Chamanara Software System Research and Development Laboratory Computer Engineering Department Amirkabir University of Technology슠 Tehran Iran

This paper presents a secure agent server named J-SAS. J-SAS is a secure and distributed execution environment for mobile agents. The core of the J-SAS is an agent virtual machine fulfilling the same functions as a traditional host machine. J-SAS considers the agent as an autonomous entity with execution code, state, specification and certification parts. J-SAS provides mobility, state dependency, run time code altering, and communications facilities. J-SAS consists of two main parts: agent gateway (AgG) and agent server (AgS). AgG is responsible for receiving agent through HTTP, authentication and delivering it with a passport to AgS. On the other side, AgS gets the agent, checks its passport, translates its code to safe code, initializes its state and runs it in a secure environment. Using resource allocation algorithms, ACL and authentication, J-SAS shows a good defensive mood against unauthorized read/write, denial of service and masquerading attacks.

关键词： Mobile agents Network servers Java Software systems Research and development Virtual machining Authentication Certification Mobile communication Web server

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