An Expert Systems Approach to Realtime, Active Management of a Target Resource

The application of expert systems techniques to process control domains represents a potential approach to managing the increasing complexity and dynamics which characterizes many process control environments. This thesis reports on one such application in a complex, multi-agent environment, with an eye toward generalization to other process control domains. The application concerns the automation of large computing system operation. The requirement for high availability, high performance, computing systems has created a demand for fast, consistent, expert quality response to operational problems, and effective, flexible automation of computer operations would satisfy this demand while improving the productivity of operations. However, like many process control environments, the computer operations environment is characterized by high complexity and frequent change, rendering it difficult to automate operations in traditional procedural software. These are among the characteristics which motivate an expert systems approach to automation. JESQ, the focus of this thesis, is a realtime expert system which continuously monitors the level of operating system queue space in a large computing system and takes corrective action as queue space diminishes. JESQ is one of several expert systems which comprise a system called Yorktown Expert System/MVS Manager (YES/MVS). YES/MVS automates many tasks in the domain of computer operations, and is among the first expert systems designed for continuous execution in realtime. The expert system is currently running at the IBM Thomas J. Watson Research Center, and has received a favorable response from operations staff. The thesis concentrates on several related issues. The requirements which distinguish continuous realtime expert systems that exert active control over their environments from more conventional session-oriented expert systems are identified, and strategies for meeting these requirements are described. An alternative methodology for managing large computing installations is presented. The problems of developing and testing a realtime expert system in an industrial environment are described

A process model of maintenance with reuse: an investigation and an implementation abstract

Sixty to eighty per cent of the software life-cycle cost is spent on the software maintenance phase because software maintenance is usually more difficult than original development and legacy systems are generally large and complex. Software reuse has recently been considered as a best solution to enhance the productivity of a software development team and to reduce maintenance costs. In addition, Software Configuration Management (SCM) is a central part of software maintenance as it is associated with changing existing software and is a discipline for controlling these changes. Thus, both software reuse and SCM have been proposed for making a significant improvement in productivity, quality and cost. However, so far these two technologies have been investigated separately. In order for software reuse and SCM to produce effects by synergy, both approaches require to be introduced into a maintenance environment together. Since software reuse and SCM, and software reuse and software maintenance have many similarities in their activities, these disciplines can be integrated within a software maintenance environment. This research has therefore developed an integrated process model for 'Maintenance with Reuse (MwR)', that supports SCM for a reuse library which is actively maintained for use in a software maintenance environment. This thesis addresses an integrated process model called the MwR model and its prototype tool TERRA (Tool for Evolution of a Reusable and Reconfigurable Assets Library) that consist of a configuration management (CM) process, reuse process, maintenance process and administration of a reuse library. The MwR model and TERRA provide reusers and maintainers with many activities of these four processes such as classifying, storing, retrieving, evaluating, and propagating reusable components, including controlling changes to both reusable components and existing systems. The process model of an integrated approach has been developed and validated using Process Weaver. The TERRA tool has been implemented on the WWW so that the prototype can provide portability, traceability, integration with existing tools, and a distributed maintenance environment. The TERRA prototype has been tested and evaluated through a scenario based case study. Several scenarios based on real data have been created and used for the case study so that an organisation can apply the model and tool to its maintenance environment without many problems. The software maintenance community is facing serious problems with legacy systems, such as a ever increasing frequency of changes and backlogs, lack of integrated tools and methods, and lack of software maintenance support environments. The control and management of changes to the software components in a reuse repository are crucial to successful software development and maintenance. If the component is being used in multiple systems effects of uncontrolled change are more critical. However, reuse libraries and servers currently available have not been successful as they do not support further development or maintenance of the reusable components. In addition, most of them are not sophisticated since they have not been linked to a development/maintenance environment. The integrated model of MwR can overcome many problems that exist in software maintenance and reuse through introduction of SCM functionalities into a maintenance environment. Thus, the integration of these common activities will greatly contribute to enhancing the productivity and quality of software, and will additionally lead to reducing the costs and backlogs of changes within a maintenance environment

LDR structural experiment definition

A study was performed to develop the definition of a structural flight experiment for a large precision segmented reflector that would utilize the Space Station. The objective of the study was to use the Large Deployable Reflector (LDR) baseline configuration for focusing on experiment definition activity which would identify the Space Station accommodation requirements and interface constraints. Results of the study defined three Space Station based experiments to demonstrate the technologies needed for an LDR type structure. The basic experiment configurations are the same as the JPL baseline except that the primary mirror truss is 10 meters in diameter instead of 20. The primary objectives of the first experiment are to construct the primary mirror support truss and to determine its structural and thermal characteristics. Addition of the optical bench, thermal shield and primary mirror segments and alignment of the optical components occur on the second experiment. The structure will then be moved to the payload pointing system for pointing, optical control and scientific optical measurement for the third experiment

Flight control system development and flight test experience with the F-111 mission adaptive wing aircraft

The wing on the NASA F-111 transonic aircraft technology airplane was modified to provide flexible leading and trailing edge flaps. This wing is known as the mission adaptive wing (MAW) because aerodynamic efficiency can be maintained at all speeds. Unlike a conventional wing, the MAW has no spoilers, external flap hinges, or fairings to break the smooth contour. The leading edge flaps and three-segment trailing edge flaps are controlled by a redundant fly-by-wire control system that features a dual digital primary system architecture providing roll and symmetric commands to the MAW control surfaces. A segregated analog backup system is provided in the event of a primary system failure. This paper discusses the design, development, testing, qualification, and flight test experience of the MAW primary and backup flight control systems

Suppression of Pilot-Induced Oscillation (PIO)

Closed loop instability caused by excess phase lag induced by actuator rate limiting has been suspected in many pilot-induced oscillations (PIOs) and oscillatory departures from controlled flight. As part of the joint AFIT/TPS program, a longitudinal pilot command notch filter activated by a real-time oscillation verifier (ROVER) algorithm was developed to eliminate the PIO source for any developing, severe PIO. Closed loop computer simulations were conducted to prepare for the flight test. The HAVE ROVER flight test project was flown using the NF-16D Variable Stability In-flight Simulator Test Aircraft (VISTA). A programmable heads-up display (HUD) was used to generate a tracking task simulating Category A fighter maneuvers. 6 of the 12 evaluation sorties were flown against an airborne target aircraft. Flight test results showed the stick filter was pivotal in preventing aircraft oscillatory departures and suppressing PIOs. With the original threshold settings, the ROVER algorithm correctly characterized pilot observations of the aircraft motion 72% of the time. Further analysis indicated that a high false detection rate was responsible for this relatively low correct detection rate. These results suggested that the threshold values used by ROVER to detect PIO were set too low. By varying the threshold values as part of a parametric study, a maximum overall correct detection rate of 82% was attained

Hormonal Changes in Pregnancy

Because of the time factor involved, it would be an impossible task to present the vast body of biochemical information accumulated during the last decade on the endocrine aspects of pregnancy. However, certain key points can be made concerning the feto-placental unit and the hormone levels and effects in normal gestation. These concepts will be discussed not merely for their academic value, but also as a base to evaluate our present diagnostic and therapeutic endeavors in obstetrical practice. With the audience’s indulgence, an occasional personal conjecture will be interjected concerning hormonal mechanisms and clinical practices

Making intelligent systems team players. A guide to developing intelligent monitoring systems

This reference guide for developers of intelligent monitoring systems is based on lessons learned by developers of the DEcision Support SYstem (DESSY), an expert system that monitors Space Shuttle telemetry data in real time. DESSY makes inferences about commands, state transitions, and simple failures. It performs failure detection rather than in-depth failure diagnostics. A listing of rules from DESSY and cue cards from DESSY subsystems are included to give the development community a better understanding of the selected model system. The G-2 programming tool used in developing DESSY provides an object-oriented, rule-based environment, but many of the principles in use here can be applied to any type of monitoring intelligent system. The step-by-step instructions and examples given for each stage of development are in G-2, but can be used with other development tools. This guide first defines the authors' concept of real-time monitoring systems, then tells prospective developers how to determine system requirements, how to build the system through a combined design/development process, and how to solve problems involved in working with real-time data. It explains the relationships among operational prototyping, software evolution, and the user interface. It also explains methods of testing, verification, and validation. It includes suggestions for preparing reference documentation and training users

High redundancy actuator

High Redundancy Actuation (HRA) is a novel type of fault tolerant actuator. By comprising a relatively large number of actuation elements, faults in the elements can be inherently accommodated without resulting in a failure of the complete actuation system. By removing the possibility of faults detection and reconfiguration, HRA can provide high reliability and availability. The idea is motivated by the composition of human musculature. Our musculature can sustain damage and still function, sometimes with reduced performance, and even complete loss of a muscle group can be accommodated through kinematics redundancy, e.g. the use of just one leg. Electro-mechanical actuation is used as single element inside HRA. This thesis is started with modelling and simulation of individual actuation element and two basic structures to connect elements, in series and in parallel. A relatively simple HRA is then modelled which engages a two-by-two series-in-parallel configuration. Based on this HRA, position feedback controllers are designed using both classical and optimal algorithms under two control structures. All controllers are tested under both healthy and faults injected situations. Finally, a hardware demonstrator is set up based simulation studies. The demonstrator is controlled in real time using an xPC Target system. Experimental results show that the HRA can continuously work when one element fails, although performance degradation can be expected.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Design definition of the Laser Atmospheric Wind Sounder (LAWS), phase 2. Volume 1: Executive summary

The LAWS phase 1 and phase 2 studies have been completed on schedule and have led to significant advances in CO2 laser development. The Phase 2 Design Definition Study has shown that a large scanning mirror/high pulse energy laser LAWS Instrument is feasible and within the existing technology. The capability to monitor wind velocities with backscatter ratios of 10(exp 11) m(exp -1) SR(exp -1) is feasible. The weight budget allocated for the baseline LAWS is adequate, and sufficient reserves exist with the potential downsized configuration. With the possible decrease in available power from the baseline of 2.2 kW guideline, power and shot management is critical for the baseline configuration (15 to 20 J). This is particularly true during the 100 day occultation period each year. With the downsized configurations (5 to 7 J), power management is still necessary during the occultation but is primarily limited to shot management over the polar regions. The breadboard effort has produced significant laser advances for a tight 18 month schedule and the minimum budgets available from NASA, Lockheed, and TDS. Using the NASA funds and Lockheed and TDS fixed assets budgets, the breadboard was designed, fabricated, and brought on-line with first laser light within 16 months after ATP. First laser beam was obtained on 21 April 1992 at a 5 J power level. Tests since then have been conducted at sustained, repetitive pulse levels of over 7 J and 20 Hz. This is an increase of over two or three times greater than any system previously developed from this type laser. Increased power levels and additional life tests will be accomplished in the next LAWS phase. The Lockheed LAWS design will operate in the gravity gradient mode on-orbit, and all possible instrument vibration and jitter modes have been considered. Adequate pointing stability and control is state-of-the-art technology for the critical time periods, frequency rates, and control responses required by LAWS. Lockheed recommends a 6-1/2 year phase C/D program for LAWS to provide adequate feedback from the engineering unit and the qualification unit to the final flight unit. Assuming a one year period for LAWS integration to the spacecraft, followed by a six-month period for launch vehicle integration, LAWS could be successfully developed and launched in eight years. Our baseline design or downsized design can be accommodated by either the Atlas 2AS or the Delta launch vehicles. Lockheed's recommendation is that, based on the successful phase 2 design study and breadboard program, a follow-on 18 month extended breadboard testing program and additional system engineering studies, primarily in interfacing with a to be defined platform, be initiated. This should be immediately followed by the phase C/D program, leading to a LAWS launch in late 2001 or early 2002