A knowledge-based decision support system in reliability-centered maintenance of HVAC systems

Studies have shown that in large physical systems, it is possible to eliminate or reduce costly machine failures, equipment downtime, lost production and decreased revenues by keeping abreast of the most effective and current maintenance techniques available. -- The purpose of this thesis is to propose a multi-faceted approach to maintenance which can address the short comings of conventional approaches to maintenance. -- The proposed methodology combines the reliability-centered maintenance technique (RCM), a fault tree analysis, a database system, and the Weibull analysis. The integration of these techniques produces an innovative system which increases the reliability and availability of the system. To the author's knowledge, this integrated approach has not been done before. -- As an example, the heating, ventilating and air conditioning (HVAC) of large buildings was used to illustrate this methodology. Failure data was collected from the Biotechnology. Arts and Administration Extension and Earth Resources Buildings of Memorial University of Newfoundland (CERR) over a six year period. The data included the time to failure and failure modes for each component within the central HVAC system. The collected data was used to quantify the reliability of the system. A probabilistic analysis based on the Weibull distribution was used to analyze the time to failure data. -- Using reliability-centered maintenance to identify the causes and impact of failures, the information acquired was used to develop fault trees. Failure modes identified in the fault trees were coded as identifiers to be used in a knowledge-based system for improving the reliability and availability of the system and its components. -- It was shown that system reliability can be improved by increasing the reliability of each component utilizing the proposed multi-faceted approach. Failure data analysis enabled us to quantify the reliability for many sub-components within the major components that constitute the HVAC system. -- It is concluded that the developed knowledge-based system enables us to troubleshoot causes of failure at a much faster rate and this will decrease the down time and increase the availability of the system

Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transpot project-demonstration act system definition

The 1985 ACT airplane is the Final Active Controls Technology (ACT) Airplane with the addition of three-axis fly by wire. Thus it retains all the efficiency features of the full ACT system plus the weight and cost savings accruing from deletion of the mechanical control system. The control system implements the full IAAC spectrum of active controls except flutter-mode control, judged essentially nonbeneficial, and incorporates new control surfaces called flaperons to make the most of wing-load alleviation. This redundant electronic system is conservatively designed to preserve the extreme reliability required of crucial short-period pitch augmentation, which provides more than half of the fuel savings

Minutes of a Regular Meeting, The University of Oklahoma Board of Regents, July 23, 1987

19810-1989

Recommended approach to sofware development

A set of guideline for an organized, disciplined approach to software development, based on data collected and studied for 46 flight dynamics software development projects. Methods and practices for each phase of a software development life cycle that starts with requirements analysis and ends with acceptance testing are described; maintenance and operation is not addressed. For each defined life cycle phase, guidelines for the development process and its management, and the products produced and their reviews are presented

A Future-Based Risk Assessment for the Survivability of Long Range Strike Systems

The United States Air Force today faces the challenge of allocating development resources to prepare for future force projection requirements. In particular, the Air Force\u27s core competency of Global Attack implies a future capability that can quickly and successfully deliver combat effects anywhere in the world with impunity. Understanding that the future threat environment is dynamic and that continued advancements by adversaries will likely degrade the technical superiority of today\u27s weapon systems, the need arises for a planning model to direct development funding to areas with the greatest probability of successfully defending the strike vehicle of 2035. Examining this problem posed two distinct challenges. The first was to determine the most likely course of Integrated Air Defense System technology through the time period of interest--allowing for plausible disruptive technologies that generate orders-of-magnitude improvement in capability or even change the nature of air defense systems. The second challenge was to characterize future adversaries--requiring a broad look at political and economic trends as presented in AF 2025, SPACECAST 2020 and other relevant future studies. Based on these studies, threat scenarios were generated from technical assessments of emerging technologies and evaluated using the Risk Filtering, Ranking and Management (RFRM) technique (Haimes, 2004) to explore the most severe threats to a future global strike air vehicle. The application of RFRM to the problem created a coherent threat hierarchy that enables the decision maker to examine anticipated hostile systems that may counter key U.S. strengths of stealth, speed, and high altitude operations. Those threat scenarios were then evaluated using decision trees and sensitivity analysis to demonstrate how quantitative tools can be applied to a largely qualitative problem

Modular space station phase B extension period executive summary

A narrative summary is presented of technical, programmatic, and planning information developed during the space station definition study extension period. The modular space station is emphasized, but tasks pertaining to shuttle sorties missions and information management advanced development are included. A series of program options considering technical, schedule, and programmatic alternatives to the baseline program are defined and evaluated

Automated Retrieval of Artifacts Created during the Software Development Life-cycle

The number of failures of software projects not meeting the originally intended requirements are many. While often due to users and developers not sharing the same vocabulary, it is more often due to changes which are not reported or recorded somewhere along the development cycle. Software traceability (ST), is the process of tracking changes in the document corpus which are created throughout the software development life-cycle. There are known techniques, such as using traceability matrices, which attempt to solve the problem. Such mechanical methods are not only manually intensive, but they totally ignore the effects of synonymy and polysemy. Latent semantic analysis (LSA) is intended to avoid these latter effects and is largely used in the world of Information Retrieval (IR). In this report we apply LSA for the purpose of maintaining artifacts generated during the software development life-cycle and place greater emphasis than hitherto found in the literature, on term extraction in software code, something we call attribute weighting. We moreover present a software tool for the automation of the traceability process, including query refinement and show that the technique allows one to trace through the artifact corpus with the confidence that the set of artifacts affected by a change will be discovered

An Analysis of Applications Development Systems for Remotely Sensed, Multispectral Data for the Earth Observations Division of the NASA Lyndon B. Johnson Space Center

An application development system (ADS) is examined for remotely sensed, multispectral data at the Earth Observations Division (EOD) at Johnson Space Center. Design goals are detailed, along with design objectives that an ideal system should contain. The design objectives were arranged according to the priorities of EOD's program objectives. Four systems available to EOD were then measured against the ideal ADS as defined by the design objectives and their associated priorities. This was accomplished by rating each of the systems on each of the design objectives. Utilizing the established priorities, it was determined how each system stood up as an ADS. Recommendations were made as to possible courses of action for EOD to pursue to obtain a more efficient ADS

Fifteen-foot diameter modular space station Kennedy Space Center launch site support definition (space station program Phase B extension definition)

This document defines the facilities, equipment, and operational plans required to support the MSS Program at KSC. Included is an analysis of KSC operations, a definition of flow plans, facility utilization and modifications, test plans and concepts, activation, and tradeoff studies. Existing GSE and facilities that have a potential utilization are identified, and new items are defined where possible. The study concludes that the existing facilities are suitable for use in the space station program without major modification from the Saturn-Apollo configuration