On the comparison of protection systems

PhD ThesisA methodology is presented for performing quantitative cost-benefit comparisons of protection systems. Protection systems in both programming languages and machine architectures can be understood and described in terms of the concept of a domain, an abstract entity which defines the access privileges of an executing program to objects in a system. Though the issues of protection and addressing can be treated separately, the realisation of the close relationship between protection and addressing can assist in the implementation of domains using addressing techniques and provides a basis for the comparison of protection systems. Current formal models of protection are seen to aid qualitative comparisons but do not provide an effective yardstick with which to compare protection systems. Based on the ideas of protection through addressing, a protection model is developed from which cost and benefit measures of protection are derived in order to achieve the quantitative comparison methodology. Two detailed examples of the application of the methodology are presented. The first concerns the protection implemented in various Algol W run-time systems, and the second compares the protection system of IBM's 370 DOS/VS operating system with a proposed alternative protection system. Finally, the comparison of protection systems which exploit structure to achieve protection is discussed. The notion of a structured domain is introduced and used in an assessment of the protection afforded by programmer defined types and a supporting architecture.The Science Research Council: The Computing Laboratory, Newcastle University

Digital Signal Processing

Contains table of contents for Part III, table of contents for Section 1, an introduction and reports on seventeen research projects.National Science Foundation FellowshipNational Science Foundation (Grant ECS 84-07285)National Science Foundation (Grant MIP 87-14969)U.S. Navy - Office of Naval Research (Contract N00014-81-K-0742)Scholarship from the Federative Republic of BrazilU.S. Air Force - Electronic Systems Division (Contract F19628-85-K-0028)AT&T Bell Laboratories Doctoral Support ProgramCanada, Bell Northern Research ScholarshipCanada, Fonds pour la Formation de Chercheurs et I'Aide a la Recherche Postgraduate FellowshipSanders Associates, Inc.OKI Semiconductor, Inc.Tel Aviv University, Department of Electronic SystemsU.S. Navy - Office of Naval Research (Contract N00014-85-K-0272)Natural Sciences and Engineering Research Council of Canada, Science and Engineering Scholarshi

An extensive English language bibliography on graph theory and its applications, supplement 1

Graph theory and its applications - bibliography, supplement

Secondary storage management in an object-oriented database management system

Ankara : The Department of Computer Engineering and Information Sciences and the Institute of Engineering and Sciences of Bilkent Univ. , 1988.Thesis (Master's) -- Bilkent University, 1988.Includes bibliographical references leaves 91-95.In this thesis, a survey on object-orientation and object-oriented database management systems has been carried out and a secondary storage management and indexing module is implemented for an object-oriented database management system prototype developed at Bilkent University. First, basic concepts, characteristics, and application areas of objectoriented approach are introduced, then, the designed prototype system is presented, the secondary storage management module is explained in detail and the functions of the other modules are summarized. Finally, the current research issues in the object-oriented database systems are introduced.Karaorman, MuratM.S

Garbage collection in distributed systems

PhD ThesisThe provision of system-wide heap storage has a number of advantages. However, when the technique is applied to distributed systems automatically recovering inaccessible variables becomes a serious problem. This thesis presents a survey of such garbage collection techniques but finds that no existing algorithm is entirely suitable. A new, general purpose algorithm is developed and presented which allows individual systems to garbage collect largely independently. The effects of these garbage collections are combined, using recursively structured control mechanisms, to achieve garbage collection of the entire heap with the minimum of overheads. Experimental results show that new algorithm recovers most inaccessible variables more quickly than a straightforward garbage collection, giving an improved memory utilisation

Development and use of computer techniques in x-ray crystallographic studies

The crystal and molecular structures of four chemically unrelated compounds have been determined by X-ray crystallography. One compound is organometallic and it crystallises in a centrosymmetric space group while the others are organic and their space groups are non-centrosymmetric. The compound bis(triphenylarsine)hexafluorobuta-1,3-diene platinum crystallises in two forms. Traditional vector methods were used to solve the structure of the isomer reported here. This is a further example of an organometallic compound where an olefin, in this case hexafluorobutadiene, is co-ordinated to the metal atom by one olefin bond to form what may be described as a 'metallo-cyclopropane'ring. Direct methods were used to determine the structures of 1,1-dichloro-2,5-diphenylcyclopropabenzene and 4,5,6-tri-O-benzoyl-2,3-di-S-ethyl-2,3-dithio-D-allose diethyl dithioacetal. In the first of these compounds the cyclopropabenzene system is not quite planar and the phenyl substituents are twisted and bent from the plane of the benzene ring in the cyclopropabenzene system. The second of these analyses confirmed the molecular configuration of the tetra-thio aldose derivative as D-allo and established that the molecule has a bent-chain conformation similar to that found in solution. The conformation of a brominated compound, extracted as an acetate derivative of formula C₃₂H₅₅O₈Br from the seaweed species Laurencia thyrsifera, has been established. The compound's structure is related to squalene and was solved using Vector methods. In addition to these analyses unsuccessful attempts to solve the crystal structures of a dinitro-imidazole derivative (C₄H₄N₄O₄) and a compound thought possibly to be a tetracyclo-decane (C₁₅H₁₂N₄) are outlined. A significant part of this project involved the further development of the X-ray crystallographic program suite of the University of Canterbury which is used in all X-ray structure analyses. Particular projects contributing to this development are discussed

Computer science: Key to a space program renaissance. The 1981 NASA/ASEE summer study on the use of computer science and technology in NASA. Volume 2: Appendices

Adoption of an aggressive computer science research and technology program within NASA will: (1) enable new mission capabilities such as autonomous spacecraft, reliability and self-repair, and low-bandwidth intelligent Earth sensing; (2) lower manpower requirements, especially in the areas of Space Shuttle operations, by making fuller use of control center automation, technical support, and internal utilization of state-of-the-art computer techniques; (3) reduce project costs via improved software verification, software engineering, enhanced scientist/engineer productivity, and increased managerial effectiveness; and (4) significantly improve internal operations within NASA with electronic mail, managerial computer aids, an automated bureaucracy and uniform program operating plans

Research reports: 1985 NASA/ASEE Summer Faculty Fellowship Program

A compilation of 40 technical reports on research conducted by participants in the 1985 NASA/ASEE Summer Faculty Fellowship Program at Marshall Space Flight Center (MSFC) is given. Weibull density functions, reliability analysis, directional solidification, space stations, jet stream, fracture mechanics, composite materials, orbital maneuvering vehicles, stellar winds and gamma ray bursts are among the topics discussed