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Theses/Dissertations

1994

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Full-Text Articles in Engineering

Impact Of Nuclear Rocket Engine Design On Control Strategies, John A. Lambright Dec 1994

Impact Of Nuclear Rocket Engine Design On Control Strategies, John A. Lambright

Nuclear Engineering ETDs

In a nuclear thermal rocket engine, the propellant gas can be varied independent of the peak chamber temperature. Startup and shutdown times can be varied over a wide range due to this uncoupling of the energy source from the working fluid. Therefore, in the early stages of nuclear rocket engine development. a study of the impact of the engine design on control strategies and systems was conducted. In order to define what is required in terms of engine thrusting times. this study focused on the thrust requirements for a Reusable Orbital Transfer Vehicle (R0TV).

Three nuclear rocket designs were used ...


On Modeling Of A Mobile Multipath Fading Channel, Heng Xiao Dec 1994

On Modeling Of A Mobile Multipath Fading Channel, Heng Xiao

Dissertations and Theses

Multipath fading is one of the major practical concerns in wireless communications. A multipath transmission takes place when a transmitted signal arrives at a receiver by two or more paths of different delay. Such multiple paths may be due to atmospheric reflection or refraction, or reflections from buildings or other objects. A multipath fading channel is usually modeled as a time-variant tapped delay system. RAKE receiver can be used to detect the signal from the multipath fading channel. However, the number of delay taps, the time delay of each path, and the tap weight for each delay path need to ...


Methodology For Accurate Speedup Prediction, Aruna Chittor Dec 1994

Methodology For Accurate Speedup Prediction, Aruna Chittor

Dissertations and Theses

The effective use of computational resources requires a good understanding of parallel architectures and algorithms. The effect of the parallel architecture and also the parallel application on the performance of the parallel systems becomes more complex with increasing numbers of processors. We will address this issue in this thesis, and develop a methodology to predict the overall execution time of a parallel application as a function of the system and problem size by combining simple analysis with a few experimental results. We show that runtimes and speedup can be predicted more accurately by analyzing the functional forms of the sequential ...


Predicting Solute Transport In Natural Streams - A Stochastic Approach, Xueqing Zhou Dec 1994

Predicting Solute Transport In Natural Streams - A Stochastic Approach, Xueqing Zhou

Dissertations and Theses

The existing theories for predicting longitudinal dispersion in straight open channels have long been recognized as inadequate when applied to natural rivers. These theories tend to grossly underestimate dispersion in real streams since an important mixing mechanism due to nonuniform river cross-section variations is not explicitly taken into account. Recognizing the important role of stream irregularities on solute transport and the analytical difficulties of classical deterministic analysis, we develop a stochastic approach for analyzing solute transport in natural streams. Variations in river width and bed elevation are conveniently represented as one-dimensional random fields, characterized by their autocorrelation functions. Advection and ...


The Kinetics Of Volatile Lead Compound Formation During Simulated Hazardous Waste Incineration, Joel Thomas Shor Dec 1994

The Kinetics Of Volatile Lead Compound Formation During Simulated Hazardous Waste Incineration, Joel Thomas Shor

Doctoral Dissertations

Air pollution from fine metal-containing particles (and vapors) formed during hazardous waste incineration has attracted less attention than other incinerator emissions. Recently, however, metal pollution has become subject to more stringent regulations. The U.S. Environmental Protection Agency has announced limitations on the emissions of ten toxic metals. Pollution control systems that will effectively remove fine (submicron) metal-containing particles from flue gases are difficult to construct. Incinerators have not been designed or operated to minimize the formation of such particles. Industrial-scale incineration testing has produced anomalous results for air emissions of lead and other metals.

To gain a better fundamental ...


Airport Security Checkpoint Screener: An Analytical Study Of Job Retention And Attrition Factors, Norman Mark St. Laurent Dec 1994

Airport Security Checkpoint Screener: An Analytical Study Of Job Retention And Attrition Factors, Norman Mark St. Laurent

Master's Theses - Daytona Beach

The proposed research seeks to identify the factors contributing to job retention and job attrition in terms of why an airport security checkpoint screener would try or want to stay on the job or leave the job. By identifying the causes of employee satisfaction and dissatisfaction, and by understanding the integral components of employee turnover can develop appropriate interventions that curb existing retention problems (exceeding 70% annually in most facilities). Aside from the obvious costs affiliated with recruiting, selecting, and training replacement employees, there is likely to be a detrimental impact on the effectiveness of airline passenger screening when a ...


The Effects Of The Proposed Larger Aircraft On Airport Capacity In The United States, Kerwin S. Mckenzie Dec 1994

The Effects Of The Proposed Larger Aircraft On Airport Capacity In The United States, Kerwin S. Mckenzie

Master's Theses - Daytona Beach

The problem of airport capacity is one that has been around for some time. With air travel projected to increase into the year 2000, Airbus Industrie, Boeing Corporation and McDonnell Douglas are making plans or are in the process of building large transports. Airbus has built the A340/A330 and is planning the now named A3XX, a 600 plus seater. Boeing is currently flying the 747-400 which holds up to 570 passengers. In addition, Boeing rolled out the 777 in June 1994, which holds up to 550 passengers. Douglas is planning the MD-12 with a 700 plus passenger load. The ...


Airbus A320/321 Quick Change Market Analysis - A Case Study, Till Christian Mommsen Dec 1994

Airbus A320/321 Quick Change Market Analysis - A Case Study, Till Christian Mommsen

Master's Theses - Daytona Beach

The purpose of this thesis is to evaluate and compare the Boeing B737 QC to the Airbus A320/321 QC aircraft, and to determine their relative market within a sample airline. The technical design of the two Airbus aircraft in a mixed QC operation were considered with respect to the requirements of a particular airline. Direct operating costs and payload range data for all three aircraft were calculated.

To evaluate the competitiveness of the A320/321 QC under actual conditions, a linear programming fleet planning model was developed that considers more than the direct operating costs of a particular aircraft ...


An Investigation And Improvement Of Electrorheological (Er) Fluid Technology, Dalal Dec 1994

An Investigation And Improvement Of Electrorheological (Er) Fluid Technology, Dalal

Master's Theses

The purpose of this research was to investigate and overcome the limitations of Electrorheological (ER) fluids and to introduce this advanced technology at WMU. Electrorheological (ER) Fluids are a special class of fluids, which exhibit a reversible, infinitely variable phase transition from a liquid to a solid/semi-plastic state, in the presence of an electric field.

ER fluids can provide a unique solution to the problems of vibration isolation of systems. The applications are currently limited due to the high voltage requirements, electric power related heating and limited research into wear/abrasive characteristics of ER fluids.

A specially designed and ...


The Effects Of Non-Uniform Blade Geometries On Cascade And Turbine Stage Performance, Maeda Dec 1994

The Effects Of Non-Uniform Blade Geometries On Cascade And Turbine Stage Performance, Maeda

Master's Theses

It is known that in-service turbomachinery blades do not have uniform shapes. There are small differences due to blade erosion, manufacturing tolerances, or faulty installation. These differences can be in the size, shape, or relative angles of the blade. In an effort to predict losses resulting from changes in blade thickness and/or blade angles, a two-part investigation has been conducted. A two-dimensional unsteady Navier-Stokes flow analysis has been used to perform numerical experiments.

First, simulations were performed for an isolated cascade. One of the two stators was scaled and/or rotated. Results of the numerical simulations show that increasing ...


A Heuristic Procedure For Designing A Cellular Manufacturing System While Minimizing Makespan, Badam Dec 1994

A Heuristic Procedure For Designing A Cellular Manufacturing System While Minimizing Makespan, Badam

Master's Theses

This study is the first of its kind in Group Technology (GT) literature and successfully demonstrates the application of the simulation technique to analyze different alternatives for machine and part grouping problem.

This study considers several aspects such as processing time, sequence of operations, alternative routing, setup time and dynamic shop condition for machine-part grouping. The heuristic developed aims to reduce intercellular moves, setup time and makespan time of parts. It also enables the decision markers to evaluate performance measures and to choose the best alternative at every step of the machine grouping process. Two examples have been used to ...


Design Of A Miniature Hydraulic Power Unit, Ryan D. Bruneau Dec 1994

Design Of A Miniature Hydraulic Power Unit, Ryan D. Bruneau

Honors Theses

The need for a newly designed miniature hydraulic power unit has received the attention of Parker-Hannifin Hydraulic Pump/Motor Division. The current power unit is no longer marketable due to the associated costs and its relative size. As a result, a miniature hydraulic power unit has been designed, the culmination to the engineering curriculum at Western Michigan University. In order to increase the overall marketability and to reduce production costs, a transparent plastic reservoir has been incorporated into the design. An appropriate polymer has been chosen to meet the design requirements and finite element analysis has been used to verify ...


An Evolutionary Approach To Allocating Tasks In Hard Real-Time Distributed Systems, Lang Dec 1994

An Evolutionary Approach To Allocating Tasks In Hard Real-Time Distributed Systems, Lang

Master's Theses

In real-time systems, correctness not only depends on the result of the computation but also on the time at which this result is available. The violation of timing constraints in hard real-time systems can be critical to human life or environment. Therefore, the scheduling algorithm for distributed systems has to allocate tasks to processing nodes so that no timing constraints can be violated. In addition to timing constraints, tasks have precedence and fault-tolerance constraints.

Static scheduling allocates tasks to processing nodes before the tasks are executed. Static scheduling problems are known to be NP-hard [4]. Therefore, heuristic techniques are necessary ...


A Pc-Based Signal Validation System For Nuclear Power Plants, Ali Seyfettin Erbay Dec 1994

A Pc-Based Signal Validation System For Nuclear Power Plants, Ali Seyfettin Erbay

Masters Theses

The safe operation and efficient control of a nuclear power plant requires reliable information about the state of the process. Therefore the validity of sensors which measure the process variables is of great importance. Signal validation is the detection, isolation and characterization of faulty signals. Properly validated process signals are also beneficial from the standpoint of increased plant availability and reliability of operator actions.

In recent years, several methods have been developed for signal validation (SV). Some of these methods include generalized consistency checking (GCC) , process empirical modeling (PEM) for prediction, multi-dimensional process hypercube (PHC), univariate and multivariate autoregression modeling ...


Erp Analysis Using Matched Filtering And Wavelet Transform, Xueming Lin Nov 1994

Erp Analysis Using Matched Filtering And Wavelet Transform, Xueming Lin

Dissertations and Theses

Event related potentials (ERP's) carry very important information that relates to the performance of the brain functions of the human being. Further studies have identified that one component, in particular, P 300, is affected by the memory process. Matched filter is used to improved the SNR of signal ERP' s. We use the output of the matched filter to distinguish the difference of the waveforms between normal subjects and memory-impaired subjects. In our study, we found that the peak values of the matched filtering output were different between normal subjects and memoryimpaired subjects. Also, as an application, wavelet transform ...


Two Dimensional Finite Element Modeling Of Swift Delta Soil Nail Wall By "Abaqus", Richard James Barrows Nov 1994

Two Dimensional Finite Element Modeling Of Swift Delta Soil Nail Wall By "Abaqus", Richard James Barrows

Dissertations and Theses

Soil nail walls are a form of mechanical earth stabilization for cut situations. They consist of the introduction of passive inclusions (nails) into soil cut lifts. These nailed lifts are then tied together with a structural facing (usually shotcrete) . The wall lifts are constructed incrementally from the top of cut down. Soil nail walls are being recognized as having potential for large cost savings over other alternatives. The increasing need to provide high capacity roadways in restricted rights of way under structures such as bridges will require increasing use of techniques such as combined soil nail and piling walls. The ...


Algorithms In Fault-Tolerant Clos Networks, Hyunyeop Lee Oct 1994

Algorithms In Fault-Tolerant Clos Networks, Hyunyeop Lee

Dissertations

No abstract provided.


Improvement Of Waterjet And Abrasive Waterjet Nozzle, Zheng Li Oct 1994

Improvement Of Waterjet And Abrasive Waterjet Nozzle, Zheng Li

Dissertations

This investigation is concerned with the improvement of the nozzle design for water and abrasive water jet machining. The mechanism of formation and characteristics of pure water and abrasive water jets are investigated in order to determine quasi-optimal process conditions.

To improve the pure water jet machining, a pulsed water jet nozzle, which employs the principle of the Helmholtz type resonator, is investigated experimentally and numerically. The experiments show the advantages of this nozzle over the commercial nozzle in cutting and cleaning. A numerical solution of the differential equations of continuity, momentum conservation, turbulent kinetic energy and dissipation for two ...


Computerized Scoring Of Sleep Stage Data, Subbarao Narayana Oct 1994

Computerized Scoring Of Sleep Stage Data, Subbarao Narayana

Theses

Sleep is a non-uniform biological state which has been subdivided into different stages. The basic criteria behind staging are the amplitude and frequency variations of sleep data. The sleep analysis is carried out by considering the characteristic variation of all three EEG, EOG and EMG signals. The polygraphic recording of nocturnal sleep is a method of research widely used in neurophysiology laboratories, both for the clinical study of sleep and for the evaluation of the therapeutic effectiveness of drugs acting on sleep. The analysis of this method is carried out by an expert individual whose depth of knowledge regarding the ...


Decentralized Optimal Control In Descriptor Systems, Hag-Yeon Park Oct 1994

Decentralized Optimal Control In Descriptor Systems, Hag-Yeon Park

Theses

Application of Matrix Minimum Principle to a linear decentralized optimal control in descriptor systems is studied in this thesis. Linear-quadratic index of performance with Gaussian initial state is considered. The necessary and sufficient conditions for optimality are derived

An additional constraint is imposed such that the controllers are linear function of output y(t) rather than of the state vector x(t). The optimal gain matrix Gi* is then specified by the necessary conditions.

Two examples are developed to illustrate the concept.


The Influence Of Hydrodynamics And Particle Size On The Rejection Properties Of Ultrafiltration Membranes, Usama M. Shahin Oct 1994

The Influence Of Hydrodynamics And Particle Size On The Rejection Properties Of Ultrafiltration Membranes, Usama M. Shahin

Theses

A mathematical model based on the flow hydrodynamics is developed to calculate the treatment efficiency of ultrafiltration process. This model relates the treatment efficiency with the consideration of both fixed parameters and variable parameters. The fixed parameters are function of the intrinsic rejection coefficient, diffusion coefficient, and viscosity whereas the variable parameters can be related to the fluid velocity, volume flux, and cartridge dimensions. The model has been examined by solutions with solutes that have different molecular weights. The experimental data fits the proposed mathematical model very closely suggesting its suitability to evaluate the rejection efficiency in ultrafiltration. As such ...


Correlation Between Tidal Volume Measured By Spirometry And Impedance Pneumography, Krithika Seshadri Oct 1994

Correlation Between Tidal Volume Measured By Spirometry And Impedance Pneumography, Krithika Seshadri

Theses

In this study, an alternative method, impedance pneumography was used to measure the respiration volume. The respiration volume was measured both by using a conventional spirometer and an impedance pneumograph, and evaluated quantitatively in 17 subjects using linear and nonlinear regression algorithms.

Data were collected from 17 normal, healthy subjects during rest and paced breathing conditions. A technique was developed to measure tidal volume by impedance pneumography. The respiration volume measured by the spirometer was correlated with the volume measured by the pneumograph. Different electrode positions and postures were included in the study to determine the position and posture which ...


Processor Allocation For Partitionable Multiprocessor Systems, Nicholaos C. Antoniou Oct 1994

Processor Allocation For Partitionable Multiprocessor Systems, Nicholaos C. Antoniou

Theses

The processor allocation problem in an n-dimensional hypercube multipro-cessor is similar to the conventional memory allocation problem. The main objective is to maximize the utilization of available resources as well as minimize the inherent system fragmentation. In this thesis, a new processor allocation strategy is proposed, and compared with the existing strategies, such as, the Buddy strategy, the Single Gray Code strategy (SGC), the Multiple Gray Code (MGC), and the Maximal Set of Subcubes (MSS). We will show that our proposed processor allocation strategy outperforms the existing strategies, by having the advantage of being able to allocate unused processors to ...


Control Of Smart Structure Using Adaptive Dither, Tian Hong Oct 1994

Control Of Smart Structure Using Adaptive Dither, Tian Hong

Theses

In this thesis, a mathematical model of a piezoelectric stack actuator is presented to describe its voltage versus displacement hysteresis characteristices. This model can accommodate a wide range of piezoelectric materials, including the PZT (lead zirconate-lead titanate) type which is most popular in industrial applications.

Besides describing the conventional "single-loop" hysteresis, this model also accounts for the off-axis minor loops by augmenting the algorithm with loop indexing.

It is shown that the PZT hysteresis possesses certain "weak scalability" that enables the use of spectral analysis to measure the level of nonlinearity.

After a suitable mathematical model has been obtained, a ...


Influences Of Cardiac And Respiratory Parameters On Heart Rate Variability, Melissa Leifer Oct 1994

Influences Of Cardiac And Respiratory Parameters On Heart Rate Variability, Melissa Leifer

Theses

Heart rate variability is a result of variation in the activity of the sympathetic and parasympathetic nervous systems. Methods have been developed to determine the level of parasympathetic activity by observing the heart rate variability spectrum. Most of the previously published research uses only level of parasympathetic activity and respiratory rate to draw conclusions about the interactions of the autonomic nervous system with physiological parameters. In order to gain a complete understanding of the autonomic nervous system and the mechanisms responsible for heart rate variability, respiratory volume, cardiac variables and pulmonary variables need to be considered. In addition, amount of ...


Data Broadcasting And Reduction, Prefix Computation, And Sorting On Reduced Hypercube (Rh) Parallel Computers, Arup Mukherjee Oct 1994

Data Broadcasting And Reduction, Prefix Computation, And Sorting On Reduced Hypercube (Rh) Parallel Computers, Arup Mukherjee

Theses

The binary hypercube parallel computer has been very popular due to its rich interconnection structure and small average internode distance which allow the efficient embedding of frequently used topologies. Communication patterns of many parallel algorithms also match the hypercube topology. The hypercube has high VLSI complexity. however. due to the logarithmic increase in the number of connections to each node with the increase in the number of dimensions of the hypercube. The reduced hypercube (RH) interconnection network. which is obtained by a uniform reduction in the number of links for each hypercube node. yields lower-complexity interconnection networks when compared to ...


Autonomic Nervous System Evaluation Using Time-Frequency Analysis, Sanjay Fernando Oct 1994

Autonomic Nervous System Evaluation Using Time-Frequency Analysis, Sanjay Fernando

Theses

Spectral analysis of heartrate variability (HRV) provided an estimate of the sympathetic and parasympatheticinfluences on heart rate without drugs or other invasive procedures.However, there are many situations where heart rate changed rapidlyover time and the control of those changes was of considerable interest.Time-frequency analysis was utilized to expand the concept of spectralanalysis of HRV to describe changes in vagal tone and sympatho-vagalbalance as a function of time. As a result the assessment of the autonomicnervous system during rapid changes in heart rate was made.

There were three advantagesto calculating vagal tone and sympatho-vagal balance by using timefrequencyanalysis. First ...


Cebus Demonstration System, Liang-Chuang Chen Oct 1994

Cebus Demonstration System, Liang-Chuang Chen

Theses

A CEBus demonstration system is constructed and applied to aspects of home automation security. Two M68HC16Z1 evaluation boards are used as CEBus nodes. Two CEBus spread spectrum power line modems (SSC PLCEMS) interconnect the nodes. An SSC PLCEMS handles all spread spectrum signal generation and reception.

The application programs in the two boards are written in assembly language based upon CAL (Common Application Language), a CEBus standard.

The standard CEBus frame format and FCS (Frame Check Sequence) are implemented by software in the Data Link Layer. Encoding and decoding binary information into UST format are implemented in the Physical Layer ...


A Distributed Network Architecture For Video-On-Demand, Ge Dai Oct 1994

A Distributed Network Architecture For Video-On-Demand, Ge Dai

Theses

The objective of this thesis is to design a distributed network architecture that provides video - on - demand services to public subscribers. This architecture is proposed as an alternative to a centralized video service system. The latter system is currently being developed by Oracle Corporation and NCube Corporation.

A simulator is developed to compare the performance of both the distributed and centralized video server architectures. Moreover, an estimate of the cost of both systems is derived using current price data.

It is shown that the distributed video server architecture offers a better cost / performance trade-off than the centralized system. In addition ...


Local Thermal Stress Factor Of Pipe-Nozzle, David Chihwei Chen Oct 1994

Local Thermal Stress Factor Of Pipe-Nozzle, David Chihwei Chen

Dissertations

A comprehensive study of local thermal stresses at the juncture of pipe-nozzle is presented in this thesis. The thermal loading is assumed to be a linear thermal gradient across the thickness of the pipe and nozzle. Currently, there exists neither experimental nor analytical data that is sufficient for pressure vessel designers to analyze the local thermal stresses at the juncture of pipe-nozzle. In order to provide a comprehensive database to calculate these thermal stresses, the finite element technique is used to provide a series of local thermal stress factor plots as a function of pipe-nozzle geometrical parameters.

For the local ...