Showing papers by "Mitre Corporation published in 1976"

An analysis of the structure and complexity of nonlinear binary sequence generators

Abstract: A method of analysis is presented for the class of binary sequence generators employing linear feedback shift registers with nonlinear feed-forward operations. This class is of special interest because the generators are capable of producing very long "unpredictable" sequences. The period of the sequence is determined by the linear feedback connections, and the portion of the total period needed to predict the remainder is determined by the nonlinear feed-forward operations. The linear feedback shift registers are represented in terms of the roots of their characteristic equations in a finite field, and it is shown that nonlinear operations inject additional roots into the representation. The number of roots required to represent a generator is a measure of its complexity, and is equal to the length (number of stages) of the shortest linear feedback shift register that produces the same sequence. The analysis procedure can be applied to any arbitrary combination of binary shift register generators, and is also applicable to the synthesis of complex generators having desired properties. Although the discussion in this paper is limited to binary sequences, the analysis is easily extended to similar devices that generate sequences with members in any finite field.

Security Kernel validation in practice

Abstract: A security kernel is a software and hardware mechanism that enforces access controls within a computer system. The correctness of a security kernel on a PDP-11/45 is being proved. This paper describes the technique used to carry out the first step of the proof: validating a formal specification of the program with respect to axioms for a secure system.

The economics of software quality assurance

Abstract: This paper presents an examination into the economics of software quality assurance. An analysis of the software life-cycle is performed to determine where in the cycle the application of quality assurance techniques would be most beneficial. The number and types of errors occurring at various phases of the software life-cycle are estimated. A variety of approaches in increasing software quality (including Structured Programming, Top Down Design, Programmer Management Techniques and Automated Tools) are reviewed and their potential impact on quality and costs are examined.

Tapping Resources in Municipal Solid Waste

Abstract: Problems to be solved and advantages offered in the recycling of municipal solid wastes are analyzed. The development of materials recovery systems is still in an elementary stage except for ferrous metals recovery. However, only a very small fraction of municipal solid waste is subjected to any type of materials recovery. The problems to be solved in the recovery of nonferrous metals, potentially the most valuable recovered products, are summarized. Glass recovery and plastics recovery are considered. The production of fuel from municipal wastes is receiving increasing interest as one way to alleviate the oil shortages. Problems other than technical to be solved in the recycling of municipal solid wastes are indicated. (JSR)

Performance prototyping of data management applications

Abstract: This paper describes the construction of a performance model or prototype of a proposed data base management system (DBMS) application by the application of certain techniques from the performance measurement and data base management disciplines. Performance measurement is conducted by using a “drive” workload that initiates the “real” workload with reasonable fidelity. The “drive” workload is constructed in terms of data base variable primitives, which are “inverted” to performance variable primitives in order to construct a resource-based drive workload. The application of this drive workload to a simulation model is illustrated, showing the use of the methodology to “tune” important DBMS, Operating System and application program parameters.

Piecewise linear predictive coding (PLPC)

Abstract: A great deal of current research in the area of narrowband digital speech compression makes use of the Linear Prediction Coding (LPC) algorithm to extract the vocal track spectrum. This paper describes a technique that splits the spectrum into two equal halves and performs a piecewise LPC approximation to each half. By taking advantage of the classical benefits of piecewise approximation, the fidelity is expected to be higher than standard LPC. In addition, by making use of under-sampling and spectrum folding, computational requirements are reduced by about 40%. PLPC has been implemented in real time on the CSP-30 computer at the Speech Research and Development Facility of the Communications Security Engineering Office (DCW) at ESD.

A control systems model of privacy

Abstract: Concerns about individual privacy, specifically in relation to automated data systems containing personal information, are considered in terms of a feedback control system model. This model provides a framework which appears to relate many separate concerns which individuals or groups have expressed about privacy. It also provides a framework which may be suitable for analyzing legislation or regulations promulgated for the protection of privacy. The model may assist in defining needed research on the need for privacy, or on the impact of inadequate protection of privacy.The model posits that data systems pose various "threats" to privacy depending on the extent and manner in which the existence of such information systems hinders the ability of individuals or groups to provide feedback to systems which affect them.

Evaluation of satellites and remote sensors for atmospheric pollution measurements

Abstract: An approach to the development of a prioritized list of scientific goals in atmospheric research is provided. The results of the analysis are used to estimate the contribution of various spacecraft/remote sensor combinations for each of several important constituents of the stratosphere. The evaluation of the combinations includes both single-instrument and multiple-instrument payloads. Attention was turned to the physical and chemical features of the atmosphere as well as the performance capability of a number of atmospheric remote sensors. In addition, various orbit considerations were reviewed along with detailed information on stratospheric aerosols and the impact of spacecraft environment on the operation of the sensors.

Application of accounting data in evaluating computer system performance

Abstract: A method of determining the utiliaztion of the processor, the channel and the disk device using the accounting data is described. Controlled experiments are performed with an IBM 370/155 in a dedicated environment using a software monitor, Configuration Utilization Evaluator (CUE). The accounting data collected by Systems Management Facility (SMF) during these experiments are used to calculate the utilization of the processor, the channel and the disk device. The calculated values compare favourably with those measured by the software monitor.

Stratospheric measurement requirements and satellite-borne remote sensing capabilities

Abstract: The capabilities of specific NASA remote sensing systems to provide appropriate measurements of stratospheric parameters for potential user needs were assessed. This was used to evaluate the capabilities of the remote sensing systems to perform global monitoring of the stratosphere. The following conclusions were reached: (1) The performance of current remote stratospheric sensors, in some cases, compares quite well with identified measurement requirements. Their ability to measure other species has not been demonstrated. (2) None of the current, in-situ methods have the capability to satisfy the requirements for global monitoring and the temporal constraints derived from the users needs portion of the study. (3) Existing, non-remote techniques will continue to play an important role in stratospheric investigations for both corroboration of remotely collected data and in the evolutionary development of future remote sensors.

Computer Systems Planning - tools & techniques

Abstract: Computer Systems Planning for a large general purpose computer facility is discussed in this paper. An overview of the planning process is presented which emphasizes development of a workload forecast and setting planning objectives. Integrated use of accounting data, synthetic programs, a system simulation program and a software monitor is described. Experiences in planning at Johnson Space Center are used to illustrate pivotal issues in the planning process.