10 research outputs found

    Architectural abstraction as transformation of poset labelled graphs

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    The design of large, complex computer based systems, based on their architecture, will benefit from a formal system that is intuitive, scalable and accessible to practitioners. The work herein is based in graphs which are an efficient and intuitive way of encoding structure, the essence of architecture. A model of system architectures and architectural abstraction is proposed, using poset labelled graphs and their transformations. The poset labelled graph formalism closely models several important aspects of architectures, namely topology, type and levels of abstraction. The technical merits of the formalism are discussed in terms of the ability to express and use domain knowledge to ensure sensible refinements. An abstraction / refinement calculus is introduced and illustrated with a detailed usage scenario. The paper concludes with an evaluation of the formalism in terms of its rigour, expressiveness, simplicity and practicality. © J.UCS

    Taguchi approach for performance evaluation of service-oriented software systems.

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    Service-oriented software systems are becoming increasingly common in the world today as big companies such as Microsoft and IBM advocate approaches focusing on assembly of system from distributed services. Although performance of such systems is a big problem, there is surprisingly an obvious lack of attention for evaluating the performance of enterprise-scale, service-oriented software systems. This thesis investigates the application of statistical tools in performance engineering domain for total quality management. In particular, the Taguchi approach is used as an efficient and systematic way to optimize designs for performance, quality, and cost. The aim is to improve the performance of software systems and to reduce application development cost by assembling services from known vendors or intranet services. The focus of this thesis is on the response time of service-oriented systems. Nevertheless, the developed methodology also applies to other performance issues, such as memory management and caching. The interaction problems of those issues are preserved for future work.Dept. of Computer Science. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2004 .L585. Source: Masters Abstracts International, Volume: 43-01, page: 0240. Adviser: Xiaobu Yuan. Thesis (M.Sc.)--University of Windsor (Canada), 2004

    Aeronautical Engineering: A cumulative index to the 1984 issues of the continuing bibliography

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    This bibliography is a cumulative index to the abstracts contained in NASA SP-7037(171) through NASA SP-7037(182) of Aeronautical Engineering: A Continuing Bibliography. NASA SP-7037 and its supplements have been compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). This cumulative index includes subject, personal author, corporate source, foreign technology, contract, report number, and accession number indexes

    NASA Tech Briefs, May 1990

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    Topics: New Product Ideas; NASA TU Services; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences

    Abstracts on Radio Direction Finding (1899 - 1995)

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    The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

    Data bases and data base systems related to NASA's aerospace program. A bibliography with indexes

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    This bibliography lists 1778 reports, articles, and other documents introduced into the NASA scientific and technical information system, 1975 through 1980

    Bowdoin Orient v.116, no.1-27 (1986-1987)

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    https://digitalcommons.bowdoin.edu/bowdoinorient-1980s/1007/thumbnail.jp

    Architecture-based performance analysis of open computer based systems

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    University of Technology, Sydney. Faculty of Engineering.NO FULL TEXT AVAILABLE. This thesis contains 3rd party copyright material. The hardcopy may be available for consultation at the UTS Library.NO FULL TEXT AVAILABLE. This thesis contains 3rd party copyright material. ----- Being able to predict the overall performance of a Computer Based System (CBS), prior to building it is one of the greatest challenges facing system engineers today. Unfortunately this is currently, arguably, something of a black art, relying on previous experience, local knowledge, and ad-hoc techniques. While good models for individual parts of many systems exist, an overall model has not yet been defined. The emerging discipline of system architecture, by defining a high level abstraction of the overall structure of the system, may provide a basis for this reasoning. In working at this high level of abstraction, a system architect is able to make fundamental design decisions, early in a project, that will affect system properties such as performance, evolvability and openness. Most importantly, it has been acknowledged that as performance is a function of the components and connections of a system, it is at the architectural level that the performance of a system can be analysed and predicted. Currently, architecture-based performance analysis work is focussed on simulating and analysing Layered Queueing Network Models (LQNM) of system architectures. It is shown that LQNMs are not suitable for architecture-based performance analysis of Open Computer Based Systems (OCBS) primarily because of their inability to deal with shared resources. OCBSs are CBSs that through the use of public, consensus-based specifications or standards, are focussed on achieving the interoperability between, and the portability of, components. It is shown that as the specification and standardisation ofboth the connections and the components of the system are of critical importance to realising the advantages of OCBSs, a layered architectural design is undertaken. This layered architectural design makes OCBSs extremely suitable to an architecture-based approach to performance analysis. An architectural model suitable for the performance analysis of OCBSs is developed, based on Activity Cycle Diagrams (ACD), that improves on the LQNM approach. The ACD based OCBS architectural model is proven to be well founded by transforming it into the existing well founded techniques of LQNMs and Timed Coloured Petri Nets (TCPN) and analysing the resultant transformations. Furthermore, the reasoning possible with the model is derived with formal analytical predictions for service, waiting and response times, bandwidths, queueing and device utilisations developed. Finally, an experimentation and simulation-based process for predicting and assessing the performance of OCBSs is defined. The process populates, implements and analyses the OCBS Architectural Model and it is proven to accurately predict the performance of a real-world case study, namely the COLLINS class submarine Open System Extension (COSE) Concept Demonstrator (CD) system. Following a literature review of the fields of Computer Based Systems, architecture, performance analysis and Open Systems, the current state of performance analysis of OCBSs is established and it is shown that an architectural model that allows the performance analysis of them is required. This OCBS Architectural Model is then developed based on a simplified OCBS reference model and the techniques of LQNMs and ACDs and formally represented and described using the Architectural Description Language (ADL) ACME. The model is then proven to facilitate performance analysis by proving it is well founded and theoretical predictions for service, waiting and response times, bandwidths, queueing and device utilisations are derived. Finally, an architecture-based performance analysis process for OCBSs is developed and shown to accurately predict the performance of a real-world case study
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