Planning and Resource Management in an Intelligent Automated Power Management System

Power system management is a process of guiding a power system towards the objective of continuous supply of electrical power to a set of loads. Spacecraft power system management requires planning and scheduling, since electrical power is a scarce resource in space. The automation of power system management for future spacecraft has been recognized as an important R&D goal. Several automation technologies have emerged including the use of expert systems for automating human problem solving capabilities such as rule based expert system for fault diagnosis and load scheduling. It is questionable whether current generation expert system technology is applicable for power system management in space. The objective of the ADEPTS (ADvanced Electrical Power management Techniques for Space systems) is to study new techniques for power management automation. These techniques involve integrating current expert system technology with that of parallel and distributed computing, as well as a distributed, object-oriented approach to software design. The focus of the current study is the integration of new procedures for automatically planning and scheduling loads with procedures for performing fault diagnosis and control. The objective is the concurrent execution of both sets of tasks on separate transputer processors, thus adding parallelism to the overall management process

Emulating Digital Logic using Transputer Networks (Very High Parallelism = Simplicity = Performance)

Modern VLSI technology has changed the economic rules by which the balance between processing power, memory and communications is decided in computing systems. This will have a profound impact on the design rules for the controlling software. In particular, the criteria for judging efficiency of the algorithms will be somewhat different. This paper explores some of these implications through the development of highly parallel and highly distributable algorithms based on occam and transputer networks. The major results reported are a new simplicity for software designs, a corresponding ability to reason (formally and informally) about their properties, the reusability of their components and some real performance figures which demonstrate their practicality. Some guidelines to assist in these designs are also given. As a vehicle for discussion, an interactive simulator is developed for checking the functional and timing characteristics of digital logic circuits of arbitrary complexity

An occam Style Communications System for UNIX Networks

This document describes the design of a communications system which provides occam style communications primitives under a Unix environment, using TCP/IP protocols, and any number of other protocols deemed suitable as underlying transport layers. The system will integrate with a low overhead scheduler/kernel without incurring significant costs to the execution of processes within the run time environment. A survey of relevant occam and occam3 features and related research is followed by a look at the Unix and TCP/IP facilities which determine our working constraints, and a description of the T9000 transputer's Virtual Channel Processor, which was instrumental in our formulation. Drawing from the information presented here, a design for the communications system is subsequently proposed. Finally, a preliminary investigation of methods for lightweight access control to shared resources in an environment which does not provide support for critical sections, semaphores, or busy waiting, is made. This is presented with relevance to mutual exclusion problems which arise within the proposed design. Future directions for the evolution of this project are discussed in conclusion

Multiprocessor graphics computation and display using transputers

A package of two-dimensional graphics routines was developed to run on a transputer-based parallel processing system. These routines were designed to enable applications programmers to easily generate and display results from the transputer network in a graphic format. The graphics procedures were designed for the lowest possible network communication overhead for increased performance. The routines were designed for ease of use and to present an intuitive approach to generating graphics on the transputer parallel processing system

Guppy: Process-Oriented Programming on Embedded Devices

Guppy is a new and experimental process-oriented programming language, taking much inspiration (and some code-base) from the existing occam-pi language. This paper reports on a variety of aspects related to this, specifically language, compiler and run-time system development, enabling Guppy programs to run on desktop and embedded systems. A native code-generation approach is taken, using C as the intermediate language, and with stack-space requirements determined at compile-time

DistriX : an implementation of UNIX on transputers

Bibliography: pages 104-110.Two technologies, distributed operating systems and UNIX are very relevant in computing today. Many distributed systems have been produced and many are under development. To a large extent, distributed systems are considered to be the only way to solve the computing needs of the future. UNIX, on the other hand, is becoming widely recognized as the industry standard for operating systems. The transputer, unlike. UNIX and distributed systems is a relatively new innovation. The transputer is a concurrent processing machine based on mathematical principles. Increasingly, the transputer is being used to solve a wide range of problems of a parallel nature. This thesis combines these three aspects in creating a distributed implementation of UNIX on a network of transputers. The design is based on the satellite model. In this model a central controlling processor is surrounded by worker processors, called satellites, in a master/ slave relationship

Design of sensor electronics for electrical capacitance tomography

The design of the sensor electronics for a tomographic imaging system based on electrical capacitance sensors is described. The performance of the sensor electronics is crucial to the performance of the imaging system. The problems associated with such a measurement process are discussed and solutions to these are described. Test results show that the present design has a resolution of 0.3 femtofarad. (For a 12-electrode system imaging an oil/gas flow, this represents a 2% gas void fraction change at the centre of the pipe) with a low noise level of 0.08 fF (RMS value), a large dynamic range of 76 dB and a data acquisition speed of 6600 measurements per second. This enables sensors with up to 12 electrodes to be used in a system with a maximum imaging rate of 100 frames per second, and thus provides an improved image resolution over the earlier 8-electrode system and an adequate electrode area to give sufficient measurement sensitivit

Higher levels of process synchronisation

Four new synchronisation primitives (SEMAPHOREs, RESOURCEs, EVENTs and BUCKETs) were introduced in the KRoC 0.8beta release of occam for SPARC (SunOS/Solaris) and Alpha (OSF/1) UNIX workstations [1][2][3]. This paper reports on the rationale, application and implementation of two of these (SEMAPHOREs and EVENTs). Details on the other two may be found on the web [4]. The new primitives are designed to support higher-level mechanisms of SHARING between parallel processes and give us greater powers of expression. They will also let greater levels of concurrency be safely exploited from future parallel architectures, such as those providing (virtual) shared-memory. They demonstrate that occam is neutral in any debate between the merits of message-passing versus shared-memory parallelism, enabling applications to take advantage of whichever paradigm (or mixture of paradigms) is the most appropriate. The new primitives could be (but are not) implemented in terms of traditional channels, but only at the expense of increased complexity and computational overhead. The primitives are immediately useful even for uni-processors - for example, the cost of a fair ALT can be reduced from O(n) to O(1). In fact, all the operations associated with new primitives have constant space and time complexities; and the constants are very low. The KRoC release provides an Abstract Data Type interface to the primitives. However, direct use of such mechanisms still allows the user to misuse them. They must be used in the ways prescribed (in this paper and in [4]) else their semantics become unpredictable. No tool is provided to check correct usage at this level. The intention is to bind those primitives found to be useful into higher level versions of occam. Some of the primitives (e.g. SEMAPHOREs) may never themselves be made visible in the language, but may be used to implement bindings of higher-level paradigms (such as SHARED channels and BLACKBOARDs). The compiler will perform the relevant usage checking on all new language bindings, closing the security loopholes opened by raw use of the primitives. The paper closes by relating this work with the notions of virtual transputers, microcoded schedulers, object orientation and Java threads

Structural dynamics branch research and accomplishments for fiscal year 1987

This publication contains a collection of fiscal year 1987 research highlights from the Structural Dynamics Branch at NASA Lewis Research Center. Highlights from the branch's four major work areas, Aeroelasticity, Vibration Control, Dynamic Systems, and Computational Structural Methods, are included in the report as well as a complete listing of the FY87 branch publications