Digital Commons Network^™

Optimization Algorithms For Shortest Path Analysis, Susan M. Hojnacki

Theses

Discrete optimization algorithms exist for analysis of network optimization of flow problems. Computer programs written from these algorithms can be used for local area network analysis of point-to-point computer networks, transportation networks, resource allocation, distribution, and production scheduling. One aspect of a network that can be optimized using discrete optimization algorithms is the length of the path that data will take when traveling through the network. One node in the network signifies the source node and a second node is the sink or destination. The object is to find the shortest path between the two nodes. The definition of shortest …

Formation Of Low Temperature Silicon Dioxide Films Using Chemical Vapor Deposition, Hsiao-Hui Chen

Theses

Low Temperature Oxide (LTO) thin films were prepared using a Low Pressure Chemical Vapor Deposition process. The process was characterized by applying traditional statistical studies and response surface technique. The uniformities within wafer and from wafer to wafer were examined by determining the mean and the standard deviation of films thicknesses. Response surface methodology was employed to determine the optimum process conditions. Time, temperature and gas flow ratio were used as the experimental factors. Index of refraction and deposition rate were used as the experimental responses. Additionally, etch rate, density, dielectric constant and infrared (IR) spectra were found for the …

Partnering: A Constructive Approach To Obtaining Engineer-Architect Services For The 1990s And Beyond, Donald E. Nations

Theses

This thesis will focus on a method of doing business in which two companies, whose businesses are complementary, work together in a relationship that strives to benefit both.

Large corporations continually examine ways to constructively manage the vast concept of change, and maintain their competitive posture. One way in which some corporations are beginning to strengthen their assets and their capabilities to deliver products or services is through a relationship known as "partnering."

As an oversimplified way of defining partnering, in a business-to-business relationship, one firm specializes in providing a service required by another company that the latter may not …

A Comparison Of Reliability Prediction Methodologies To Observed Field Failure Data, Randal Butturini

Theses

Reliability predictions of electronic equipment are considered highly valuable; yet the most widely used technique, Military Handbook 217 is criticized as inaccurate. The industry response to the Handbook has been to develop a myriad of methodologies for failure rate prediction. This paper uses four (4) reliability prediction methods to forecast the failure rate of two (2) circuit boards for which a field failure history exists. The predicted failure rate for each procedure on each board is compared to the actual failure rate; and a first-order correction factor is calculated.

Design And Simulation Of A Primitive Risc Architecture Using Vhdl, Evangelos Moustakas

Theses

Hardware Description Languages are used as the connecting links between the design of a digital system and the way this design is being represented in computers, with the ultimate goal being the simulation and verification of that design before the construction of any prototype. In this thesis, we follow all the steps of a RISC architecture design and finally use VHDL as the tool to describe, simulate and verify the design. By the unique abilities of VHDL we give both a structural and a behavioral description where the latter contains multiple description levels, from gate to Processor-Memory-Switch (PMS) . The …

Low Pressure Chemical Vapor Deposition (Lpcvd) Of Silicon Carbide From Diethylsilane, Yi-Tong Shi

Theses

The depositions of amorphous and cubic-crystal SiC from a new chemical vapor deposition source, diethylsilane(DES), have been studied. Amorphous SiC thin films and crystalline cubic-SiC materials have been deposited on silicon wafers at temperature lower and higher than 850C, respectively. The activation energy and a reaction mechanism involving the production and subsequent desorption of diethylsilene has been suggested, which explains the observed deposition dependency with the temperature and reactor pressure. A model based on the polymerization of DES is offered and the deposition rate is found to be the result of a large number of simultaneously occuring deposition processes for …

Implementation Of An Integrated High Energy Beam Workcell, Varadaraj Souda

Theses

This study is an effort to advance the technology of machining by High energy beams. Investigation of the Waterjet, Plasma and the Oxyfuel beams was carried out to explore novel machining techniques. The study was focussed on three major objectives.

One of the major objectives was to set up an Integrated beam workcell consisting of the three beams. A hydroabrasive waterjet workcell was modified to install the three cutting tools to be along the same line of traverse. An integrated beam consisting of the thermal and the waterjet beams was produced because of this arrangement. The feasibility of using the …

A Biomechanical Analysis Of Three Humeral Fracture Fixation Systems, Alina Michelle Waite

Theses

Often, humeral fractures requiring internal fixation can be a challenging orthopaedic procedure. Each method of treatment possesses clinical and biomechanical advantages and disadvantages. Rigid plate fixation is highly successful in treating a large variety of long bone fractures. Nevertheless, excessive soft tissue dissection is necessary, and vascular and neural anatomy of the humerus can make plate application and removal difficult. An intramedullary nail offers a relatively simple procedure, thereby reducing these anatomical concerns. However, rotational instability at the fracture site is a common complication with a conventional intramedullary nail. Thus, a study was conducted to evaluate a new interlocking intramedullary …

Mobile Manipulator Path Planning By A Genetic Algorithm, Min Zhao

Theses

The thesis addresses the path planning problem for a mobile manipulator system which is used to perform a sequence of tasks specified by locations and minimum oriented force capabilities. The problem is to find an optimal sequence of base positions and manipulator configurations for performing a sequence of tasks given a series of task specifications. The formulation of the problem is nonlinear. The feasible regions for the problem are nonconvex and unconnected. Genetic algorithms applied to such problems appear to be very promising while traditional optimization methods cause difficulties. Computer simulation is carried out on a three degrees-of-freedom manipulator mounted …

Mobile Robot Path Planning Based On Hierarchical Hexagonal Decomposition, Dan Zheng

Theses

In this thesis, a new algorithm based on hierarchical cell decomposition and artificial potential field is developed to solve the find-path problem for a mobile robot. The basic cell structure used for decomposition is a hexagon. The artificial potential field is based on an attractive force from the goal position and repelling forces from the obstacles. Computer simulations of the algorithm for various obstacle scenarios are also presented.

Biodegradation Of Diflufenican Using Anaerobic Microbial Consortia, Velukumar T. Nanjagowder

Theses

In this thesis I examine the feasibility of using anaerobic microbial consortia from digested anaerobic sludge to degrade Diflufenican, a fluorinated herbicide released into the environment as a result of agricultural usage. The compound is manufactured by Rhone Poulenc and it is an active ingredient of agricultural herbicides. The anaerobic digested sludge served both as a source of microorganisms and as a growth medium. Initial studies were conducted by making a stock solution of 1 ppm concentration of Diflufenican in acetone, the optimal solubility of the compound as suggested in the material safety data sheet is 0.05 ppm in water. …

Nontraditional Machining Techniques With Emphasis On Waterjet Milling, Shiv K. Kunapuli

Theses

The rapid growth of harder and difficult-to-machine materials over the past two decades necessitates the development of compatible nonconventional machining techniques, as detailed in this work, with special emphasis on one of the most recent machining method, the abrasive-waterjet technique(AWJ).

The feasibility of using AWJ for milling on glass is investigated. Due to the large number of parameters involved in the AWJ technique, and the multitude of machining requirements, optimization of performance is the focus. These parameters include waterjet pressure, particle size, abrasive flow rate, traverse rate and number of passes.

Surface topography is found to be a function of …

Performance Of The Extended Token Bus Network With Asymmetric Load Distribution, Hong Lin

Theses

The Token Bus, IEEE 802.4, provides high priority message options. The delay of high priority messages becomes an important criterion in the design and management of computer communication networks. A goal of the protocol is to allocate sufficient bandwidth and frequency of access to minimize of the high priority message delay. In this study, a simulation model of a priority based network, consisting of two token bus networks interconnected by a bridge is implemented. The load distribution among stations is asymmetric and the messages are divided into two priorities, high and low. Both fixed and variable token token holding times …

The Performance Evaluation Of A New Neural Network Based Traffic Management Scheme For A Satellite Communication Network, Dequan Liu

Theses

The thesis describes a new neural network based traffic management scheme for a satellite communication network. The scheme consists of two levels of management. The front end of the scheme is a derivation of the Kohonen's self-organization model to configure maps for the satellite communication network dynamically, The model consists of three stages. The first stage is the pattern recognition task which selects an exemplar map that best meets the current network requirements. The second stage analyzes the discrepancy between the chosen exemplar map and the state of the network, and adaptively modifying the chosen exemplar map to conform closely …

An Approach To Improving The Antithrombogenesis Of Pneumatic Diaphragm Artificial Ventricle : Fabrication And Design Considerations, Hui-Sun Wang

Theses

Thrombus formation is one of the major problems in artificial heart development and its clinical applications. In order to improve the antithrombogenesis in the artificial ventricles, three aspects of investigation have been done in the laboratory.

1] the surface features and the surface defects on specially prepared samples made of polyurethane and silicon rubber were studied and analyzed by scanning electron microscopy ( SEM ), light microscopy and KEVEX Feature Analysis for understanding and controlling the blood contacting surface.

2] the polyurethane blood contacting surface with smooth surface fabricated by solution cast process, the material treatment, and the fabrication procedure …

Graded Buried Channel Charge Coupled Device Design, Zengjing Wu

Theses

A process and device simulation study has been made to optimize a new type of buried channel CCD (BCCD) structure to be referred to as Graded BCCD (GBCCD) whose buried channel is formed by multiple implantations for achieving higher charge transfer efficiency. The 2-D process simulation tool SUPREM4 and 2-D device simulation tool PISCES2 were used in this research. The simulation results of the GBCCD with double channel implants are compared with the previously obtained experimental results.

Triple channel implants under the conditions of various process parameters were also simulated and the optimized case was chosen on the base of …

A Three-Dimensional Finite Element Stress Analysis Of Interface Conditions In Porous Coated Hip Prosthesis, Siu-For Yau

Theses

A three-dimensional finite element model of a collar-type hip stem and both the cortical and cancellous bones is used to investigate the stress distributions on an implanted femoral stem, adjacent bone, and specifically at the bone/implant interface for various amounts of porous coating and different stem materials. The finite element model consists of 909 nodes comprising 536 linear eight-node solid brick elements and 176 two-node interface elements. The finite element analysis code employed is SUPERTAB from SDRC. The interface elements consist of coincident-node spring elements and gap elements which model the rigidly bonded and loose interfaces respectively. Local coordinate systems …

Measurement Of The Electrical And Optical Properties Of Thermid Polymide, Zhixiong Zhu

Theses

Electrical and optical properties of spin-coated THERMID polyimide EL-5010 have been studied and evaluated in this thesis. The D.C. bulk resistivities of 0.96^-2.56 μm thick samples were measured to be 10¹⁶ Ω-cm over the 27-160°C range using a test system consisting of Keithley 236 Source-Measure Unit. The bulk resistivity decreased to 2 x 10¹⁴Ω-cm at 200?C. The surface resistivity, 10¹⁵Ω/0 , and breakdown voltage, 350 V/pm, were also measured. The fixed charge concentration and mobile ion concentration in the THERMID polyimide EL-5010 insulator of a MIS capacitor structure were measured using a high …

Work-Preserving Real-Time Emulation Of Meshes On Butterfly Networks, Alf-Christian Achilles

Theses

The emulation of a guest network G on a host network H is work-preserving and real-time if the inefficiency, that is the ratio W_G/W_H of the amounts of work done in both networks, and the slowdown of the emulation are O(1).

In this thesis we show that an infinite number of meshes can be emulated on a butterfly in a work-preserving real-time manner, despite the fact that any emulation of an s x s-node mesh in a butterfly with load 1 has a dilation of Ω(logs).

The recursive embedding of a mesh in a butterfly presented by …

Adaptive Filter Application In Fetal Electrocardiography, Xueqiang Zhou

Theses

A hybrid adaptive algorithm for cancelling the maternal electrocardiography (MECG) component in abdominal fetal electrocardiography(FECG) is described. This algo rithm combines the advantages of the orthogonal algorithm which was developed by Reichert(1977) and the multiple reference noise cancelling adaptive algorithm which was developed by Widrow(1975).

The simulating experiment was taken to test all of these three algorithms. It demonstrated that all these three algorithms can cancel the abdominal component of the maternal ECG with three limb lead ECG signals. and the hybrid algorithm is at least as effective as each other algorithm alone. In this experiment, the abdominal ECG signal …

A Microengineered Beam Diaphragm Structure For The High Performance Pressure Sensor, Alkesh Shah

Theses

The thesis details the design for a novel microengineered beam diaphragm structure for piezoresistive pressure sensor applications. The beam diaphragm structure is used as a pressure sensing device, within a Wheatstone bridge circuit. The single crystal silicon with [100] orientation is used for the beam diaphragm structure.

It has the advantages of high sensitivity(2.56 v/v/mm of Hg), good linearity(3Kpa to 1.4 Mpa) and overpressure protection with the help of the bosses. It's protection range is about 400 times the standard pressure range. The beam diaphragm structure has two rectangular bosses which are formed by anisotropic etching. Two pairs of diffused …

Oscillatory Potentials Model And Parameter Identification, Huizhong Pan

Theses

Two mathematicals model are presented for the oscillatory potentials of the electroretinogram. These models represent the oscillatory potential in terms of sets of parameters whose values may provide information of diagnostic value.

The test setup and protocol for obtaining the oscillatory potentials are described, as well as the data processing including acquisition up to identification of the model parameters.

Data from eight subjects, five normals and three diabetics, were used to evaluate the two models. These preliminary test results show a marked difference in the values of some of the model parameters between normals and diabetics.

Studies Of Electrical Properties Of Sio2 /Inp System, Milind S. Patel

Theses

Analyses of Electrical characteristics, of TilAu/SiO₂1InP structures, are presented here. The (MIS) Metal-Insulator- Semiconductor capacitors were fabricated with oxide thickness of 195nm, 420nm and 610nm respectively. The SiO₂ films were deposited on n-type Indium Phosphide(/nP) using Rapid Thermal Chemical Vapor Deposition (RTCVD). The characterization techniques employed in these experiments were (I-V) Current Voltage and High Frequency Capacitance Voltage (C-V) techniques. The electrical parameters obtained from the I-V and C-V measurements have been discussed here.

Mapping Hierarchical Structures Onto Hypercubes, Sandip C. Patel

Theses

Hierarchically structured arrays of processors are appropriate for low-level and intermediate-level image processing and computer vision. The most widely used structure is the pyramid. Neverthless, pyramid machines do not support the efficient implementation of the majority of scientific algorithms and their cost may become prohibitively high. In contrast, hypercube machines efficiently implement a wide variety of important algorithms due to the versatility of the underlying network. In fact, hypercube-based systems have become commercially available. The hypercube network supports both regular and irregular communications and it can efficiently simulate a variety of other structures like rings, trees, meshes, pyramids, etc. Thus, …

Low-Temperature Crosslinking Of Polycyclopentadiene, Lawrence Peters

Theses

Cyclopentadiene was polymerized via a Diels-Alder mechanism at 174°C under an inert atmosphere. The polymer obtained after ll hrs of reaction had a low bulk viscosity of 8 cps and a viscosity-average molecular weight, Mv, of up to 3000. An unsaturated polyester was synthesized from maleic anhydride and ethylene glycol in the presence of chlorosulfonic acid at room temperature. The polyester had an intrinsic viscosity of 0.024 cps. At 60°C, polycyclopentadiene (PCPD), and the unsaturated polyester were reacted to yield a viscous liquid which was crosslinked at room temperature over 48 hours in the presence of styrene, triethyleneglycol dimethacrylate (TEGDMA), …

Efficient Multiprocessor Scheduling Based On Genetic Algorithms, Hong Ren

Theses

The problem of multiprocessor scheduling can be stated as finding a schedule for a general task graph to be executed on a multiprocessor system so that the schedule length can be minimized. This scheduling problem in known to be NP-hard and methods based on heuristic search have been proposed to obtain optimal and sub-optimal solutions to the problem. Genetic algorithms have recently received much attention as robust stochastic searching algorithms for various optimization problems. In this thesis, we propose an efficient method based on genetic algorithms to solve the multiprocessor scheduling problem. The representation of the search node will be …

Electrical Characterization Of Preoxide Growth Fluorine Incorporated Thin Sio2 Films, Nilay J. Patel

Theses

Analyses of electrical characterization, of thin SiO₂ films grown on virgin and etched silicon surfaces, are presented here. The characterization techniques employed in these experiments are High Frequency Capacitance-Voltage (C-V), Capacitance-Time (C-T) & MOS Doping Profile and Static & Dynamic Current-Voltage (I-V) measurements. The structures, with areas ranging from 0.001-0.05 cm², used in this study are Al/Poly/SiO₂/Si/Al capacitors fabricated on virgin and C₂F₆ CHF₃ + He plasma exposed n-Si substrates. In this experiment, we have studied the effect of sacrificial oxidation. In this step, the oxide is thermally grown on the …

The Electronic Interpreter For The Deaf, Young-Jun Ko

Theses

None provided.

Computational Analysis Of Space Transfer Vehicle Engine Turbopump Diffuser Design For Deep-Throttling, Gordon J. Wissinger

Theses

Space Transfer Vehicles (STV) are expected to perform missions (orbital transfer, Lunar/Mars transfer and descents) which will require deep-engine throttling thrust capability. To accomplish this, turbopumps which can efficiently provide a wide range of flow outputs are needed. The current state-of-the-art cryogenic fuel and oxidizer turbopump designs do not perform efficiently at off-design flow rates mainly due to stall and flow separation in the diffuser. This thesis examines how boundary layer control techniques can be used to control, reduce or eliminate diffuser flow separation. A finite element based code, FIDAP, was used to study flow in a diffuser by developing …

The Dynamics Of A Moving Boundary Between Immiscible Fluids In A Porous Medium, John Mccarvill

Theses

The analysis and simulation of the dynamics of a moving boundary between immiscible fluids in a porous medium is presented. One fluid is introduced under prescribed inlet boundary conditions and the motion of the resulting interface boundary is studied. The aforementioned scenario is simulated using a finite element based software, FIDAP. Analytical solutions developed in one dimension illustrate the concepts and serve as a benchmark for numerical solutions. The aim of computer simulation is to develop a model applicable to real situations, yet flexible enough for future adaptations to other problems with little modification.