This paper presents a study of the Computer Aided Design (CAD) needs for the Facilities Engineering Division (PENGD) of NASA Langley Research Center. PENGD currently has many more projects than resources. Government cuts and reductions in personnel promise to make the situation worse. PENGD needs to increase the throughput of its existing staff while also decreasing the product cycle of a project. The existing design scenario with PC based CAD is used as a baseline to evaluate possible improvements and cost savings by implementing workstation based CAD with feature-based solid modeling. A detailed case study is used to illustrate and compare the differences in designing with AutoCAD1 and ProlEngineer. Equivalent hourly engineering rates are calculated for each system based on a four year life cycle. The results of the case study and engineering rates are used to determine the actual cost of designing with both CAD systems. A costlbenefit analysis is used to determine the cost effectiveness of continued use of PC based CAD with complex design projects versus the purchase and integration of workstation based CAD. My findings conclude that projects with any degree of uncertainty benefit from workstation based CAD. Solid modeling provides a mechanism for thorough study which reduces modifications, rework, and schedule delays. The associative database greatly reduces the amount of time required to create and update drawings. As uncertainty increases, the savings from using workstation based CAD over PC based CAD also increases. / Master of Engineering

Master of Science

<p>The actor model provides a framework for writing concurrent programs. ACT ++ is an implementation of the actor model in C++, allowing concurrent programs to be written in an object-oriented style. In ACT++, each actor is an object possessing one or more independent threads of control. Version 2.0 of ACT ++ uses the PRESTO threads package. As PRESTO threads are available only for certain architectures and operating systems, its use does not meet one of the goals of ACT ++, namely portability among a variety of architectures. To facilitate portability, ACT++ 3.0 is written using the IEEE POSIX 1003.4a standard for threads (Pthreads). This project deals with the implementation of ACT++ 3.0, the testing of the implementation, and its performance.</p> / Master of Science

<p>A key cause of poor system performance is inherently due to the lack of understanding of system behavior. Performance problems are especially apparent in parallel and distributed programs, for which expected speedup is difficult to achieve. Theoretical models and trace visualization tools are suitable for extracting insights into the behavior of a system. Theoretical models available today work for certain types of systems and require possibly unrealistic assumptions, and hence are not considered here. Existing trace visualization tools have yielded new insights into the behavior of the sequential, parallel, and distributed programs. However, they have two inherent limitations: (1) Each tool visualizes only one execution of a program. (This is dangerous when analyzing concurrent programs, which are prone to non-deterministic behavior.) (2) The applicable domain of a visualization tool will be limited unless the tool incorporates a large variety of methods to visually display data. This is because a single display method may yield new insights into only certain systems. In addition, finding the "right" display that can provide the needed insights is a potentially time-consuming process. This project carries through the previous work-CHITRA92. This project addresses these limitations by providing the following four capabilities to analyze traces: (1) CHITRA93 analyzes a set (or ensemble) of traces to obtain the typical behavior of a system. (2) CHITRA93 incorporates three transforms to simplify ensembles by reducing either the state space size or the interval over which time is defined in the ensemble. (3) CHITRA93 builds compact summary of the dynamic behavior (or model) of a system from an ensemble. (4) CHITRA93, to avoid building models that poorly fit an ensemble, provides a suite of methods to partition ensembles into mutually exclusive, exhaustive, and homogeneous subsets so that each subset displays "similar" behavior. These methods include several visual techniques and statistical methods. Finally, a portion of the project seeks to stabilize and to produce a correct version of CHITRA.</p> / Master of Science

<p>Since the discovery that cis-diamminedichloroplatinum (II) possessed great antitumor properties, researchers have been synthesizing and screening metal coordination complexes for their potential anti-tumor activity. Hundreds of compounds have been tested, and few compounds possessed anti-tumor activity. This paper examines how the physical and chemical properties of complexes of the platinum group metals affect their toxicity and anti-tumor activity.</p> / Master of Science

Master of Science

Undependable systems are unable to accomplish the mission for which they were designed and cause tremendous loss [Airwar-Vietnam, 1978]. In most instances, timely maintenance is a vital necessity for a system to be kept in or returned to its operating condition, and to be able to successfully complete a specific mission. In a scarcer-resource but higher-competition environment, it is essential that system dependability be considered as a major system parameter and be evaluated during the early phases of the system design process. Given a specific system mission profile, whether or not the mission can be successfully completed is based not only on such measures as performance, reliability, maintainability, and/or availability. There is a need for system designers and engineers to meeasure system dependability, as well. System dependability is a measure of effectiveness which allows for the consideration of maintenance in the life cycle as long as it does not inhibit the system from fulfilling its mission. It is the aim of this project to develop a methodology for the analysis and evaluation of system effectiveness through the utilization of the system dependability measure. The concept and the mathematical model of system dependability is discussed. Effectiveness factors and relationships are described, a measure of system dependability has been defined, and a computer -based tool was developed to enable the accomplishment of trade-off analyses and the evaluation of various system configurations in terms of dependability. Maintenance requirements are addressed through the introduction of various combinations of failures, and failure distributions include the consideration of the exponential, Weibull, and log-normal cases. Application of the dependability model is illustrated through a case study involving an aircraft radar trated through a case study involving an aircraft radar is illustrated through a case study involving an aircraft radar subsystem as an example. / Master of Science

<p>The goal of this project was to develop part of the environment that would allow the creation of distributed applications in ACT++. ACT++ is a programming framework in which concurrent object-oriented programs can be written in C++. The concurrent objects in ACT ++ are called actors. Specifically, the project is concerned with the development of a communication infrastructure that configures a collection of heterogeneous machines for use in the distributed version of ACT++.</p> <p> A utility, "ActorControl," was implemented through which the user can specify how ACT ++ is to run on each of the nodes by means of a configuration file. The "ActorControl" utility starts a process on each of the nodes specified in the configuration file and establishes TCP socket based connections among all of them. To simplify the communication between the different nodes, a special type of actor called an interface actor is used. Instead of issuing communication requests directly to sockets, a request is directed to an interface actor that is responsible for that socket. A related project is concerned with the problems of creation, destruction and invocation of the methods on the remote machine.</p> <p> Thus the project consists of two parts. The first part is the implementation of the "Actor Control" utility that establishes socket connections among all the nodes participating in the distributed ACT ++. The second part is the implementation of the interface actors that are present at each end of the connection between any pair of machines.</p> / Master of Science

<p>The effectiveness of a material handling system is essential to a competitive manufacturing environment. Automatic Guided Vehicles (AGVs) are an irnportant technology within today's modern manufacturing facility. Academic programs in manufacturing and industrial engineering must find ways to include this technology in their instructional and research programs to provide the students with sufficient knowledge to address material handling systems design. This project was a first step in the development of such a facility at Virginia Polytechnic Institute and State University.</p> <p> This project accomplished two main objectives. The first one was to create a functional AGV system with the "Orbitor" Automatic Guided Vehicle that incorporates advanced hardware features. This system included a taped guide path with bar codes on the floor, and the communication linkage via wire and radio frequency between the Orbitor on-board computer and a remote computer. The second objective was to establish a software system for the overall control of the Orbitor AGV system. This objective involved creating software for the on-board computer and the remote computer. Software communication protocols were implemented and tested between the remote computer and the Automatic Dispatching Unit, and between the Intersection and Communications Unit and the on-board computer. The user of this system was able to interactively define tasks for the AGV from the remote computer. The AGV provided feedback to the remote computer on the status of the vehicle and it sent appropriate messages when the tasks were complete.</p> / Master of Engineering

Goal setting is one of the most effective techniques developed for enhancing performance. This paper has presented an outline of how the principles of goal setting might be applied to offensive football. <p>As teams and situations vary greatly, it was not the focus of this paper to provide exact goals and examples for every situation, but rather to suggest how the principles of goal setting might be adapted to an offensive football setting, and to suggest resources that a coach might use in adapting this program to fit his/her particular needs. Goal setting enables coaches to be sure that appropriate amounts of time are spent on all areas relating to football, and that the time spent on these areas is maximized. By using the principles outlined in this paper, a coach can begin to apply the powerful techniques of goal setting to their teams practices and games, and begin using it to effectively to enhance team performance levels. / Master of Science