A system of self maintenance for fault detection and correction in a highly automated system is presented in this thesis. The self maintenance scheme consists of three parts: a watchdog monitor for fault detection, a diagnoser to pinpoint the exact component failure, and a method of repair. The second part of the scheme, the diagnoser, is developed in detail and applied to the teleoperated THAW telescope. The THAW telescope is an Earth-bound prerunner of the Astrometric Telescope Facility (ATF), an approved payload of the forthcoming International Space Station Freedom (SSF). The simulation of the ATF is modified to produce permanent hardware failures. A diagnoser is created using shallow reasoning and a rule base which pinpoints the most likely failure(s) with reasonable success. Implementation of the watchdog monitor and the repair system is left for future work.

This thesis presents a method to reconfigure objects in an articulated robotic hand, where reconfiguration is defined as moving an object from one orientation in the hand to another orientation. Several methods using object configuration rely on a stationary work area. These methods assume that the object is stably grasped by the hand, and is moved around the work area in an assembly process. This thesis assumes that the hand is the primary obstacle. The object now reacts to the hand instead of the work area. Reconfiguration of the object within the hand is the goal. Models were developed that portrayed the mechanics and the contacts for frictionless manipulation in a plane. Contact formation trees used in conjunction with the simulated mechanics is a unique method for solving this problem; the solution we attain is an optimal reconfiguration plan. (Abstract shortened with permission of author.)

Flexible manipulators provide significant advantages over the commonly-used rigid robots due to their lightweight properties, but an accurate control of these manipulators is more difficult to attain, and it is especially demanding in task executions involving changing payloads. This thesis addresses the problem of payload adaptive control of flexible manipulators. The nonlinear model describing the manipulator dynamics is completely derived and is then used for an accurate computer simulation of the flexible manipulator motions. Payload identification is implemented by using a novel neural network approach to identify distinct payload classes from tip deflection patterns which result from different payloads. The identification procedure is then used to select a controller which best meets the control objectives specifying hub speed and maximum tip deflection. Two distinct controller synthesis procedures, one using a pole-placement design and one employing a variable structure technique, are developed. The merits of payload adaptive control are shown by several simulation experiments.

This thesis introduces the problem of knowledge acquisition in developing a Trouble Shooting Guide (TSG) for equipment used in integrated circuit manufacturing. TSG is considered as a first step in developing an Expert Diagnostic System (EDS). The research is focused on the acquisition and refinement of actual knowledge from the manufacturing domain, and a Hierarchical Data Collection (HDC) system is introduced to solve the problem of bottleneck in developing EDS. An integrated circuit manufacturing environment is introduced, and issues relating to the collection and assessment of knowledge concerning the performance of the machine park are discussed. Raw data about equipment used in manufacturing environment is studied and results are discussed. A systematic classification of symptoms, failures, and repair activities is presented.

Stochastic activity networks (SANs) have been used in the modeling of computer systems because of their suitability in representing distributed systems. SANs may be solved by analysis or by simulation. When simulation is used, future events list management is very time consuming, as with other simulation techniques. New methods that take advantage of the SAN model structure are presented which significantly reduce the cost of future events list management. Multiple future events lists are used to reduce operations required upon each state change.

<p> In a large-scale outdoor, airborne, hazardous materials (HAZMAT) incident, such as ruptured chlorine rail cars during a train derailment, the local Incident Commanders and HAZMAT emergency responders must obtain accurate information quickly to assess the situation and act promptly and appropriately. HAZMAT responders must have a clear understanding of key information and how to integrate it into timely and effective decisions for action planning. This study examined the use of HAZMAT plume modeling as a decision support tool during incident action planning in this type of extreme HAZMAT incident. The concept of Situation Awareness as presented by Endsley's dynamic situation awareness model contains three levels: perception, comprehension and projection. It was used to examine the actions of incident managers related to adequate data acquisition, current situational understanding, and accurate situation projection. Scientists and engineers have created software to simulate and predict HAZMAT plume behavior, the projected hazard impact areas, and the associated health effects. Incorporating the use of HAZMAT plume projection modeling into an Incident Action Plan may be a complex process. The present analysis employed a mixed qualitative and quantitative methodological approach and examined the use and limitations of a "HAZMAT Plume Modeling Cycle" process that can be integrated into the incident action planning cycle. HAZMAT response experts were interviewed using a computer-based simulation. One of the research conclusions indicated the "HAZMAT Plume Modeling Cycle" is a critical function so that an individual/team can be tasked with continually updating the hazard plume model with evolving data, promoting more accurate situation awareness.</p>

Markovian and self-similar data traffic models are currently being proposed as accurate characterizations of the way data traffic behaves on an asynchronous transfer mode (ATM) network. Because of the dearth of traffic data from real ATM networks, researchers in this area have relied on simulated data and data from Ethernet networks. Ethernet and ATM are both packet technologies and share some similarities. There are, however, important differences between the two technologies which largely preclude the use of Ethernet traffic data in studies of ATM network traffic behavior. We propose a model for ATM data traffic based on analysis of traffic traces from two real ATM networks. This analysis reveals that the interarrival time distribution for data traffic is bimodal, in a similar fashion to Ethernet, but is a mostly lognormal mixture distribution with a very small self-similar or pseudo self-similar portion in the right tail / acase@tulane.edu

This study was designed to explore the relations between some aspects of the global digital and human development over the last decade, using an analytical framework which includes factors considered to have an impact on national development suggested by theory and practice. The operational definition of the global digital divide linked access, adaptation and creation of information and knowledge via the use of digital information and communication technologies to national development processes, within a demographic, economic, political and social context. The methodology carried out to analyze the relations between the global digital divide and national development included the construction of a quantitative model for 174 developed and developing countries which explained more than 91% of the variability in development in 1997 in terms of the national info tech infrastructure, and another quantitative model which explained more than 43% of the changes in development over the last decade in terms of the national core computing and network capacity. Findings from the study suggest the existence of an S-shaped curve depicting differences between inadequate, weak, medium and strong national info tech infrastructures. In conclusion, the existence of a significant, strong and positive relation between national core computing and network capacity and progress in national development in developing countries over the last decade suggests that this single factor will play an increasingly important role in the near future / acase@tulane.edu

In this research, a theoretical foundation for modeling, analysis, and testing of a system for voltage collapse is developed. The boundary theorem of the load flow feasibility region (FR) is presented. Based on the proposed boundary theorem, a method of voltage stability analysis referred to as the Eigen-Structure Analysis (ESA) method, is developed that does not require complicated nonlinear programming calculations for evaluation of the closest unfeasible or boundary injection corresponding to a given power network operating point with voltage controlled and load buses. Furthermore the steady-state stability margin and the sensitivity of the stability margin to bus voltages and bus injections are defined. An algorithm for determining the stability margin and its sensitivity to bus voltages and bus injections is proposed which is capable of handling large scale power systems by utilizing the sparse matrix techniques for saving computation time and memory space. The unification of the concept of feasibility region and the concept of multiple load flow solution is also presented in this dissertation The Eigen-Structure Analysis method is applied to a number of test system models. The simulation results confirm the theory and show that the proposed stability margin decreases monotonically to zero when the system approaches voltage collapse. The voltage-weak points and key contributing factors affecting the system voltage instability can be identified according to the values of the sensitivity of the stability margin to bus voltages and bus injections / acase@tulane.edu

In this dissertation, we present an Extended Object Model (XOM) for the design and development of Knowledge Based Management Systems (KBMS). We define a set of operations on the object model and explain the semantics of the model in terms of first order logic. To study the inferencing capabilities of the graph underlying our model, we introduce the notion of XOM graph and capture the behaviors of the object classes present in a XOM through an Action Integrated Extended Object Model (AIXOM). Furthermore, we incorporate imprecision in XOM in the basic object types as well in their abstractions. We apply the XOM in conceptualizing the design of Knowledge Based Management Systems and propose a KBMS Developing Environment (KBMSDE) on the basis of that design. Subsequently, we show that the set of XOM operations is complete in KBMSDE and then outline the ways of implementing imprecision in it. At a deeper level of abstraction, we conceptualize the Knowledgebase, the KBMS Shell and the Knowledge-Editor, all constituents of a KBMS. We analyze the XOM graph, derived from its associated Rulebase, for its connectivity in relation to its inference intensive completeness and describe the activities of the Shell and the Editor through their AIXOM. To explain and illustrate the underlying theories, we provide several examples. Finally, we compare the capabilities and limitations of our approach with other models with an insight to future research in this area. / Source: Dissertation Abstracts International, Volume: 52-08, Section: B, page: 4304. / Major Professor: Abraham Kandel. / Thesis (Ph.D.)--The Florida State University, 1991.