Engineering Commons^™

Grid Generation And Flow Computation About A Martian Entry Vehicle, John Edward Stewart

Mechanical & Aerospace Engineering Theses & Dissertations

A number of vehicles are currently being proposed for a manned mission to Mars. One of these vehicles has a modified blunt-nosed cone configuration. Experimental results have been obtained for this vehicle in 1968. These results show lift-over-drag ratios comparable to those needed for Mars entry. Computations are performed here to verify the earlier results and to further describe the flight characteristics of this vehicle.

An analytical method is used to define the surface of this vehicle. A single-block volume grid is generated around the vehicle using an algebraic Two-Boundary Grid Generation algorithm (TBGG) and transfinite interpolation. Euler solutions are …

Investigation Of Mixing Characteristics Of A Lox Injector Operating At Non-Ideal Thermodynamic Conditions, W. Wei

Mechanical & Aerospace Engineering Theses & Dissertations

The mixing characteristic of a liquid oxygen (LOX) injector operating under nonideal thermodynamics conditions are analyzed. Oxygen, in supercritical state, is injected into a high pressure airstream flowing through a narrow annulus region of a hypersonic wind tunnel. The objective of the present study is to investigate conditions that would help produce a uniform profile of oxygen concentration at the end of a diverging mixing channel, located downstream of the injector section. Uniformity of oxygen concentration profile is critical to combustion processes that occur downstream of the LOX injector section.

The coupled velocity, temperature, oxygen concentration and enthalpy fields are …

Finite Element Formulation And Numerical Simulation Of The Large Deflection Random Vibration Of Laminated Composite Plates, Jay Howard Robinson

Mechanical & Aerospace Engineering Theses & Dissertations

A theoretical large deflection finite element formulation is developed for the purpose of simulating the random vibration of thin generally laminated composite plates. The random acoustic load is taken to be stationary and Gaussian with zero mean and uniform magnitude and phase over the surface of the plate. In­ plane inertia terms are included in the formulation however rotary inertia terms are assumed negligible.

The integration routine is derived from a set of unified single step algorithms, using a weighted satisfaction of the equilibrium equation. The algorithm is second order accurate and unconditionally stable for particular values of its free …

An Artificial Neural Approach To The Decomposition Problem, Chandrashekar L. Masti

Electrical & Computer Engineering Theses & Dissertations

The goal of this thesis is to develop an artificial neural approach toward addressing the intractability involved with the decomposition problem. The search for the lattice of substitution property (s. p.) partitions essential to decompositions is cast into the framework of constraint satisfaction. An artificial neural network is developed to provide solutions by performing optimization of a mathematically derived objective function over the problem space. The issue of transitivity is verified to belong to a class of problems beyond the scope of solvability for conventional quadratic-order constraint satisfaction neural networks. A theorem is stated and proved establishing that third-order correlations …

Improving Solids Conveying In Plasticating Extruders : An Investigation Into Manufacturing Processes And Manufacturing Systems For Profiled Thermoplastic Pellets, Oommen Cherian

Theses

The objective of the thesis is the manufacture of thermoplastic bilobal and trilobal profiled pellets for the determination of the interparticulate co-efficient of friction exhibited by solid beds of such pellets. The enhancement of the interparticulate coefficient of friction is expected to lead to ameliorated solids conveying rates in plasticating extruders.

Predicting the product shape from a profile die is very difficult due to the elastic memory of plastics and the complex boundary conditions. Consequently the cost involved in experimenting with different profile dies is high. Therefore a standard die with several die inserts of varying cross-sections were used to …

Small Disturbance Stability As Affected By Excitation Controls, Alfredo Flores

Theses

The effect of excitation control systems on the power system's small disturbance stability limits has been investigated in this thesis. Three excitation control schemes namely the proportional, fast?acting and the modified fast?acting have been studied.

The stability results were predicted directly in terms of the AVR gain controlling parameters following one?dimensional and two?dimensional frequency domain separation technique. The necessary algorithms and computer simulation programs have been developed.

In case of a modified fast?acting excitation control with three unknown variables, a procedure has been proposed to obtain the stability results by extending the two?dimensional frequency domain separation technique.

Effect Of Moisture On Microcircuit Failure, Chandrabala D. Patel

Theses

Stability and reliability of microcircuit is dependent on its design, fabrication, testing, storage and use.

In this thesis emphasis is given on various failure mechanisms of Integrated Circuits in humid environment and techniques of improving reliability. Other factors which affect the failure of integrated circuits are also discussed. Moisture induced failure modes, semi-reversible failures and irreversible failures (surface leakage current and corrosion-causing interruption of interconnection lines) are also reviewed.

Controlling the contaminants and moisture related corrosion are also covered. The quickest way to evaluate the reliability of microcircuit is by accelerated aging test and by selection of meaningful criteria of …

Damage Effects To Si-Sio2 Structures Due To Reactive Ion Etching, Moshe D. Bunyan

Theses

This thesis presents the damage effects to the Si ? SiO₂ structures due to Reactive Ion Etching (RIE). The research was carried out on Si ? SiO₂ MOS capacitors which were fabricated using RIE and wet etch (Hydrofluoric acid etch (HFE)) Process. The experiment was carried out using CV technique and Ellipsometry. Various electrical parameters were measured from CV *curves of these MOS capacitors. It was observed that the CV curve obtained for the RIE etched sample showed considerable deviation from that of the control sample. This indicates the presence of excess of interface trap charge density which …

A Systematic Evaluation Technique For Assisting In The Identification And Prevention Of Wrist Stress In The Work Place, Karen Kleinfeld

Masters Theses

Carpal Tunnel Syndrome is a cumulative trauma disorder involving compression of the median nerve within the wrist. This disorder has become an industrial epidemic, striking workers whose daily activities involve repetitive motion, wrist deviation, awkward finger postures, and excessive forces to the hand. In an effort to identify and control existing trauma, as well as prevent the onset of further cases of CTS, a systematic evaluation technique has been developed to assist in the ergonomic analysis of the work place. This assessment technique identifies and quantifies occupational risk factors of a task that may predispose workers to CTS. With this …

Modcad: A Graphic Predetermined Time Standards Software For The Ibm P.C., Raad A. Dawood

Masters Theses

MODCAD is a software program designed to give MODAPTS (MODular Arrangement of Predetermined Time Standards) the capability to generate workplace layouts that can be used in conjunction with the time study analysis. Software packages have been developed for MODAPTS such as MODAPTS Plus and Task Master that allow the user to input the predetermined codes of MODAPTS.

AutoCAD (a computer aided design software) is used to combine MODAPTS codes and workplace layout drawings in a single environment by customizing the standard AutoCAD menus and icons to include the MODAPTS codes and routines. AutoLisp (AutoCAD resident language) is used to write …

Computer Aided Localization Of Neurological Diseases, Yusuf Parlar

Dissertations

Computers in medicine has brought new dimensions and better understanding of uncertainties in the field of medical sciences in the last decade. This thesis is focused upon the localization of neurological lesions in the human nervous system. It relates clinical neurological test outcomes to pathways of function or malfunction. Certain methods are proposed-empirical. stochastic. Deterministic-to estimate the spatial distributions of lesion probabilities.

First. a Bayesian model is presented to estimate the posterior probability of lesion from a priori information, based on the test outcomes. Due to unavailable data alternative methods and models are presented: Regression Analysis. Monte Carlo simulation, and …

On The Performance Of Minimum Redundancy Array For Multisource Direction Finding, Byung-Seub Lee

Dissertations

As an application of power spectrum estimation, the multi-source direction finding has been evolved from conventional FFT method to Superresolution methods such as Multiple Signal Classification(MUSIC) algorithm. Uniform Regular Array(URA) was mainly used in all these approaches.

The Minimum Redundancy array(MRA); a non-uniform thinned array which results in an input signals covariance matrix with minimum redundancy has been shown to have certain interesting properties for spectrum estimation. Only recently it was suggested to use the MRA for spatial estimation. The purpose of this research was to study the performance of this array in multi-source direction finding estimation and compare it …

Computer Modeling And Analysis Of Biological Rhythms, Shi Xiong Yang

Dissertations

Biological rhythms are an important phenomenon and feature of physiologic systems. Indirect means have to be employed for their description and exploration due to the unclear internal nature of the system. This study analyzed and developed several possible mathematical models using single or multidimensional nonlinear differential equations to approach the experimental circadian data. The numerical solutions of the models were obtained by computer simulation and the simulated and experimental acquired circadian data were analyzed in both the time and frequency domains. Phase plane plots, phase response curves and power spectrum analysis were employed to determine the nonlinearity of the system …

Mass Transfer Of Hazardous Organic Compounds In Soil Matrices Relevant To Thermal Desorption/Incineration, Jong-In Dong

Dissertations

Soils contaminated with hazardous organic compounds have been known to threaten human health both directly through various contact mechanisms and indirectly through leaching or transfer to the food chain. Thermal desorption of contaminated soil matrices with secondary treatment of the effluent gases (collection, incineration, etc) is one of most feasible and developing technologies for cleaning of contaminated soils. There is, however, little known about the mass transfer principles of organic contaminants through the heated soil matrices. The objectives of this study is, therefore, to learn and understand details of the mass transfer processes of organic compounds in these soil matrices. …

A Comparative Study Of Edge Detection Techniques, Jaskaran Singh Dhaliwal

Theses

The problem of detecting edges in gray level digital images is considered. A literature survey of the existing methods is presented. Based on the survey, two methods that are well accepted by a majority of investigators are identified. The methods selected are: 1) Laplacian of Gaussian (LoG) operator, and 2) An optimal detector based on maxima in gradient magnitude of a Gaussian-smoothed image. The latter has been proposed by Canny[], and will be referred as Canny's method. The purpose of the thesis is to compare the performance of these popular methods. In order to increase the scope of such comparison, …

An Artificial Neural Network For Redundant Robot Inverse Kinematics Computation, Wibawa Utama

Theses

A redundant manipulator can be defined as a manipulator that has more degrees of freedom than necessary to determine the position and orientation of the end effector. Such a manipulator has dexterity, flexibility, and the ability to maneuver in presence of obstacles. One important and necessary step in utilizing a redundant robot is to relate the joint coordinates of the manipulator with the position and orientation of the end-effector. This specification is termed as the direct kinematics problem and can be written as x = f(q)
where x is a vector representing the position and orientation of the end-effector, q …

Design And Analysis Of Movable Boundary Allocation Protocol, Karun Sekhri

Theses

The increasing digital communications traffic will require very high speed networks. The use of high communication speed increases the ratio between end to end propagation delay and the packet transmission time. This increase causes rapid performance deterioration and restricts the utilization of the high system bandwidth in broadcast channel based systems. Using several parallel channels in place of a single channel improves this ratio. For a given system bandwidth the total system capacity is increased by bandwidth division and parallel communication. FTDMA protocols have been suggested for the parallel channel network and these protocols are suitable for different loads. In …

An Investigation Of The Dynamics Of Abrasive Waterjet Formation, Md. Ekramul Hasan Khan

Theses

The aim of this research was to investigate the jet formation and the jet behavior, as characterized by the velocity field, the force exerted by the jet on a work-piece and the jet geometry. The velocity and force distributions were measured using a laser transit anemometer (LTA) and a piezoelectric force transducer (PFT) respectively for constant water pressure (334.6 MPa) supply. The jet structure and its instantaneous behavior were visualized by the used of high speed filming. LTA and PFT measuring techniques were established and verified. The measurements were performed under different operating conditions. It was found that at a …

Statistical Process Control For High Precision Deep Drawn Sheet Metal Parts, Sunil S. Shah

Theses

In today's world, industrial expertise has come to be judged in terms of the quality of the product. Good quality has become the ultimate aim in a manufacturing environment, which leads to many innovations for ease in the inspection of parts. In considering a metal working company like Hudson Tool & Die Company, a study of the various operations and the application of Statistical Process Control to the forming operations is performed using STORM software. Important characteristics have been carefully studied with regards to metal forming like uniform metal thickness, radius of the bend, depth of the drawing operation. In-depth …

Control Of Stress In Silicon Nitride Thin Films, Ajay Krishnan

Theses

Silicon nitride thin films of varying composition and thickness were deposited on silicon substrates by reactive rf diode sputtering of a silicon target using an argon/nitrogen gas mixture. Film stoichiometry could be controlled by varying the partial pressure of nitrogen, the total sputtering gas pressure and the target rf power. Films with refractive index of 2.01, the value for stoichiometric silicon nitride, could be obtained. Film stress was measured by wafer curvature; refractive index and thickness of deposited films were obtained by ellipsometry and interferometry measurements. The etch rate in buffered HF for films with refractive index 2.05 was 29A/min; …

Multiprocessor System Design Tutor : Expert System Approach, Rakesh Kamdar

Theses

To increase computational bandwidth and system resilience, integration of several microprocessors in a single system becomes necessary. The overall throughput and efficiency of such a system is directly dependent on the hardware and software interconnection supported by the basic microprocessor chip. Sometimes it becomes difficult to put together all the information for design criteria and all the design related formulas.

The approach made here is to continuously update the hardware and software information in the database related to a given microprocessor. This information can be accessed at any time for efficient design solution. Intel 80386 and Motorola 68020 microprocessors are …

Construction Cost Estimating In Project Management, Kalpit N. Patel

Theses

The primary objective of Cost Estimating is to support the timely generation of bid or alternative estimates. Cost Estimating also supports management analysis of estimate accuracy, reasonableness and project risk through the generation of summary reports and analysis. Estimates also provide a base of information during construction for such items as scope changes to the contract, variations in costs of the project cost, total project cost, feedback for scheduling etc.

Contruction cost estimating is the process of identifying and compiling the many items of cost that will enter into a construction project. This is a procedure that requires very detailed …

A Study Of The Effects Of Weighting Matrices In Power System State Estimation, Yanshi Wang

Theses

The effects of weighting matrices that may be used in the Weighted Least Squares (WLS) method when applied to the problem of Power System State Estimation (PSSE) are studied. These weighting matrices include the one usually used in the literature and the one used in the utility PSSE programs

The performances of these weighting matrices are compared using the Monte Carlo simulation technique.

To test the performances of the weighting matrices, a PSSE program is developed, different performance indices for state comparison are defined, and many cases are studied.

Results show that the weighting matrix usually used in literature, 1/σ², …

Experimental Evaluation Of Process Zone Deformation In Concrete, Cherng-Maou Meng

Theses

Concrete structures are often subjected to a variety of loading conditions. Under ultimate load design, concrete structures can resist these loads without evident deformation. However, under service, tension cracks will develop and depending on their location, they may impair load carrying capacity.

It is generally believed that microcrack development is preceeded by formation of a relatively long microcracked region. A large number of studies have indicated that due to formation of this process zone (microcracked zone), Linear Elastic Fracture Mechanics (LEFM) principles are not applicable to concrete. However, a number of nonlinear models can be developed if the length of …

Design Of A Real Time Optical Sensor For Continuous Blood Cell Separation, Girish S. Yerande

Theses

For continuous measurement and display of oxygen saturation and RBC content in blood during cell separation a reflection type optical sensor is designed based on the theoretical model using the photon diffusion theory. The prototype sensor consists of two arrays of light emitting diodes, red and infrared, and photodiodes. The emission wavelength of LEDs are 660 nm and 800 nm. The 800 rim which is in the infrared region is very close to isobestic value for blood. The prototype sensor is mounted on the blood cell separator equipped with an antitwister mechanism. Each LED emits a specific wavelength of light …

Configuring Maps For A Satellite Communication Network By Self- Organization, Yizhong Chen

Theses

There are several management tasks in a telecommunication network. Among which traffic management is one of the most important and difficult tasks. It is concerned with maximizing network efficiency when the network is under stress either due to overload or failure. New attempts to automate this task such as expert system based approach are yet to be perfected. In this thesis, we advocate a new concept of traffic management. Our scheme consists of two levels. At the first level, we introduce a Self-organization model to dynamically configure a map for a satellite communication network. The second level is a routing …

Prestressed Concrete Columns Under Bending And Axial Load, Ajit Chiplunkar

Theses

A general analysis and design equation for slender and nonslender prestressed concrete columns subjected to uniaxial or biaxial moments combined with axial load is proposed. The proposed equation is an extension to the one developed by Hsu for reinforced concrete columns. The analytical results of the ultimate loads of eccentrically loaded slender prestressed columns are compared with the experimental results reported by Brown and Hall and Aroni respectively. The comparative study shows that the proposed equation of interaction diagram is in good agreement with the actual tests.

The ultimate loads of biaxially loaded short columns are also compared with the …

Three Dimensional Finite Element Analysis Of A Tibial Ankle Prosthesis, Harrison Philip Crowell Iii

Theses

In this study, three dimensional finite element analysis is used to evaluate and compare partially and fully porous coated tibial components, of an ankle prosthesis, implanted in the distal tibia. The geometry of the distal tibia is determined from measurements of cross sections of a human tibia. From the measurements, solid models of the cancellous and cortical bone are created. A solid model of the tibial component is created and positioned in the solid model of the bone. From the solid model, a finite element model is created for the partially coated case and for the fully coated case. Each …

A Micro-Based Machine Vision System, Hsueh-Chung Michael Feng

Theses

In this thesis, a low-cost general purpose machine vision system based on a personal computer of the PC-XT/AT family and an electronic camera controller based upon a Motorola 6811C11 single-chip microcontroller has been designed and implemented. This work is focused on image formation. The system supports a long distance camera-computer configuration. A picture editor, generic image manipulation software was designed and implemented. A single computer can supervise multiple cameras.

Analysis Of The Effects Of Biofeedback On Cardiovascular And Neuromuscular System, Andreas T. Gikas

Theses

Time series signal processing techniques (Fourier based) were applied to study the effects of biofeedback on the cardiovascular and neuromuscular system.

A medical instrumentattion system was developed to monitor ECG, EEG and EMG biopotential signals and temperature.

Data from two experiments were first analyzed. These data were from two normal male subjects who engaged in relaxation techniques (Transcendental Meditation & Imagery). If we assumed that for both subjects relaxation produced a decrease of the sympathetic activity then that resulted in a decrease of the heart rate (ECG) and an increase in skin temperature. Spectral analysis of the EEG signal showed …