This thesis addresses software evolution from the perspective of standards interoperability. We address the issue of how to apply contemporary software safety assurance standards to legacy safety-critical systems, with the aim of recertifying the legacy systems to the contemporary standards. The application of RTCA DO-178B Software Considerations in Airborne Systems and Equipment Certification to modified legacy software is the primary focus of this thesis. We present a model to capture the relationships between pre- and post-modification software and standards. The proposed formal model is then applied to the requirements for RTCA DO-178B and MIL-STD-498 as representative examples of contemporary and legacy software standards. The results provide guidance on how to achieve airworthiness certification for modified legacy software, whilst maximizing the use of software products from the previous development.

The breakdown of Dennard's transistor scaling has driven computing systems toward application-specific accelerators, which can provide orders-of-magnitude improvements in performance and energy efficiency over general-purpose processors. To enable the radical departures from conventional approaches that heterogeneous systems entail, research infrastructure must be able to model processors, memory and accelerators, as well as system-level changes---such as operating system or instruction set architecture (ISA) innovations---that might be needed to realize the accelerators' potential. Unfortunately, existing simulation tools that can support such system-level research are limited by the lack of fast, scalable machine emulators to drive execution. To fill this need, in this dissertation we first present a novel machine emulator design based on dynamic binary translation that makes the following improvements over the state of the art: it scales on multicore hosts while remaining memory efficient, correctly handles cross-ISA differences in atomic instruction semantics, leverages the host floating point (FP) unit to speed up FP emulation without sacrificing correctness, and can be efficiently instrumented to---among other possible uses---drive the execution of a full-system, cross-ISA simulator with support for accelerators. We then demonstrate the utility of machine emulation for studying heterogeneous systems by leveraging it to make two additional contributions. First, we quantify the trade-offs in different coupling models for on-chip accelerators. Second, we present a technique to reuse the private memories of on-chip accelerators when they are otherwise inactive to expand the system's last-level cache, thereby reducing the opportunity cost of the accelerators' integration.

A thesis submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, for the degree Doctor of Philosophy. / Real-time computer control is characterized by the need for a high degree of lnteraction between some machine or physical process, its controlling computer, and the human operator. recently there has been a trend towards the use of distributed real-time computer systems which potentially offer greater functional flexibility, better maintainability and better reliability than centralized systems, The increasing demands that are being placed on real-time computer control systems have highlighted the deficiencies of current heuristic design techniques and emphasised the need Ior solid theoretical design precepts. / AC2017

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Includes bibliographical references (leaves 75-76). / This report documents the initial development of a computer-controlled system for the production of three-dimensional forms. The project involved the design and construction of a carving device which was attached to an existing x-y plotter. The carving device was connected to a computer graphics system and various ways of using that system for three-dimensional design were explored. The material being carved is styrene foam in blocks, 4' x 4' x 1'. These carved blocks have potential use as sketches in exploring sculptural form, or as molds for the production of works in concrete fiberglass, or metal. / by Robert Faught. / M.S.

Cheang Sio Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1990. / Bibliography: leaves [103-106] / Chapter 1. --- THE EMERGENCE OF WINDOW SYSTEMS --- p.1-1 / Chapter 2. --- THE NEED OF A CHINESE WINDOW SYSTEM --- p.2-1 / Chapter 3. --- REQUIREMENTS AND DIFFICULTIES OF DEVELOPING A CHINESE WINDOW SYSTEM --- p.3-1 / Chapter 3.1. --- Input Method and Character Encoding --- p.3-1 / Chapter 3.2. --- Layout Direction and Formatting Mechanism --- p.3-3 / Chapter 3.3. --- Fonts --- p.3-3 / Chapter 3.3.1. --- Bitmap font --- p.3-4 / Chapter 3.3.2. --- Outline font --- p.3-6 / Chapter 4. --- A TRIAL TO OVERCOME THE DIFFICULTIES IN SUPPORTING CHINESE FONTS - OVERVIEW OF A CHINESE FONT SERVER SYSTEM --- p.4-1 / Chapter 4.1. --- Network Font Server --- p.4-3 / Chapter 4.2. --- Local Font Server --- p.4-4 / Chapter 4.3. --- Fonts --- p.4-5 / Chapter 4.3.1. --- Bitmap font --- p.4-5 / Chapter 4.3.1. --- Outline font --- p.4-5 / Chapter 4.4. --- Caching --- p.4-6 / Chapter 5. --- ORGANIZATION OF THE CHINESE FONT SERVER SYSTEM --- p.5-1 / Chapter 5.1. --- Communication Module --- p.5-2 / Chapter 5.1.1. --- Client connection request channel --- p.5-3 / Chapter 5.1.2. --- Client communication channels --- p.5-3 / Chapter 5.1.3. --- Network server connection channel --- p.5-4 / Chapter 5.2. --- Client Service Module --- p.5-7 / Chapter 5.2.1. --- Font manipulation module --- p.5-7 / Chapter 5.2.1.1. --- Request to open a new font --- p.5-8 / Chapter 5.2.1.2. --- Request to close an opened font --- p.5-8 / Chapter 5.2.1.3. --- Request to load a font character --- p.5-9 / Chapter 5.2.2. --- Cache module --- p.5-10 / Chapter 6. --- FROM THE CHINESE FONT SERVER SYSTEM TO A CHINESE WINDOW SYSTEM --- p.6-4 / Chapter 7. --- SCREEN FONTS --- p.7-1 / Chapter 7.1. --- Hand-edit --- p.7-3 / Chapter 7.2. --- Bitmap Scaling --- p.7-3 / Chapter 7.3. --- Outline Scaling --- p.7-5 / Chapter 7.4. --- Manual Refinement --- p.7-16 / Chapter 8. --- FONT CACHING --- p.8-1 / Chapter 8.1. --- Font Caching Strategies --- p.8-1 / Chapter 8.1.1. --- Pre-loading --- p.8-1 / Chapter 8.1.2. --- Fix-loading --- p.8-4 / Chapter 8.1.3. --- Demand loading --- p.8-6 / Chapter 8.1.3.1. --- Least Recently Used (LRU) replacement --- p.8-9 / Chapter 8.1.3.2. --- Least Frequently Used (LFU) replacement --- p.8-9 / Chapter 8.1.4. --- Hybrid loading --- p.8-16 / Chapter 8.2. --- Retrieval Method --- p.8-22 / Chapter 8.2.1. --- Binary searching --- p.8-22 / Chapter 8.2.2. --- Tree searching --- p.8-24 / Chapter 8.2.3. --- Hash searching --- p.8 26 / Chapter 8.3. --- Cache Expansion and Retraction --- p.8-33 / Chapter 9. --- AN EXPERIMENTAL CHINESE FONT SERVER SYSTEM - CAPABILITIES AND RESTRICTIONS --- p.9-1 / Chapter 9.1. --- Experimental Servers --- p.9-1 / Chapter 9.2. --- Programming Interfaces --- p.9-3 / Chapter 9.2.1. --- Connection request --- p.9-3 / Chapter 9.2.2. --- Open and close fonts --- p.9-4 / Chapter 9.2.3. --- Request to load cache --- p.9-5 / Chapter 9.2.4. --- Change the current font --- p.9-5 / Chapter 9.2.5. --- Request a font character --- p.9-5 / Chapter 9.3. --- Testing Applications --- p.9-6 / Chapter 9.4. --- Statistics --- p.9-8 / Chapter 9.4.1. --- Cache performance --- p.9-8 / Chapter 9.4.1.1. --- Tests --- p.9-8 / Chapter 9.4.1.2. --- Results --- p.9-10 / Chapter 9.4.1.3. --- Discussion --- p.9-10 / Chapter 9.4.2. --- Local Server Vs. Network Server --- p.9-12 / Chapter 9.4.2.1. --- Tests --- p.9-12 / Chapter 9.4.2.2. --- Results --- p.9-13 / Chapter 9.4.2.3. --- Discussion --- p.9-13 / Chapter 9.4.3. --- Outline Font --- p.9-14 / Chapter 9.4.3.1. --- Tests --- p.9-14 / Chapter 9.4.3.2. --- Results --- p.9-14 / Chapter 9.4.3.3. --- Discussion --- p.9-15 / Chapter 10. --- EPILOGUE --- p.10-1 / Chapter 10.1. --- Conclusion --- p.10-1 / Chapter 10.2. --- Future Extension --- p.10-2

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With the rising popularity of Web-based applications, the Web browser platform is becoming the dominant environment in which users interact with Internet content. We investigate methods of discovering information about network performance characteristics through the use of the Web browser, requiring only minimal user participation (navigating to a Web page). We focus on the analysis of explicit and implicit network operations performed by the browser (JavaScript XMLHTTPRequest and HTML DOM object loading) as well as by the Flash plug-in to evaluate network performance characteristics of a connecting client. We analyze the results of a performance study, focusing on the relative differences and similarities between download, upload and round-trip time results obtained in different browsers. We evaluate the accuracy of browser events indicating incoming data, comparing their timing to information obtained from the network layer. We also discuss alternative applications of the developed techniques, including measuring packet reception variability in a simulated streaming protocol. Our results confirm that browser-based measurements closely correspond to those obtained using standard tools in most scenarios. Our analysis of implicit communication mechanisms suggests that it is possible to make enhancements to existing “speedtest” services by allowing them to reliably determine download throughput and round-trip time to arbitrary Internet hosts. We conclude that browser-based measurement using techniques developed in this work can be an important component of network performance studies.

Typescript, etc. / Digitized by Kansas Correctional Industries

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Typescript (photocopy). / Digitized by Kansas Correctional Industries