Engineering Commons^™

Experimental Investigation Of Submerged, Turbulent, Axisymmetric Air Jet Impinging On A Flat Plate, Lan Xiao

Theses

Experimental investigation was carried out on the flow characteristics of a circular, submerged, turbulent, axisymmetric air jet impinging normally on a smooth, flat, square, Lucite plate and a sand paper covered plate. Jet issuing from a circular nozzle of 0.5 inch diameter while the Reynolds Number varying from 10,000 to 85,000 was investigated. The flow can be considered incompressible since the pressure and the velocity of the jet were not too high, with Mach Number of the order of 0.3.

Various flow parameters were measured to obtain the velocity and pressure distributions at the surface of the flat Lucite plate, …

Comparison Between Stimulated Emg And Natural Emg, Zak Belfki

Theses

The electromyograph (EMG) signal generated from a cat's jaw muscle in movement, is analyzed. After a series of experiments at UMDNJ, three major categories of EMG were recorded: rest EMG, biting EMG and hissing EMG.

The biting files contained a series of EMG collected in successive episodes. Power spectrum and statistical analysis were applied to the episodes. Each episode had approximately 43,000 samples. Results showed that these episodes had a similar spectrum with statistically the same mean and variance.

The hissing files were produced by electrical stimulation of the hypothalamus and contained EMG embedded in a stimulus artifact. The problem …

Statistical, Random And Fractal Characterizations Of Surface Topography With Engineering Applications, Gongyao Zhou

Dissertations

Two methods, namely the conventional and fractal geometry methods, are developed for surface topography characterization. The conventional method utilizing statistical and random process techniques is used to study waterjet machined surfaces. In the study the waterjet surfaces are separated into smooth and striation zones, where striation influence is negligible in the smooth zone. It is found that the smooth zone has a random, moderately isotropic texture, with the height distribution nearly Gaussian. In the striation zone the major frequencies of the surface profile power spectra are independent of cutting parameters, while the amplitudes of these frequencies monotonically increase with cutting …

Constitutive Equation For Concrete Using Strain-Space Plasticity Model, Yuxiang Xing

Dissertations

Plasticity theory has been used to model the concrete constitutive relationship for about two decades. With the modifications and refinement based on experimental data, achievement has been made in these plasticity models for concrete. Almost all the existing models are developed in stress space. With a lot of experimental data and more understanding about stress states of concrete, the stress-space model shows many advantages. Because of this and also due to conventional engineering practice, the stress-space plasticity approach has been in the dominant position. However, the conventional stress-space plasticity method has one inherent drawback in which it cannot deal with …

On Orthogonal Collocation Solutions Of Partial Differential Equations, Herli Surjanhata

Dissertations

In contrast to the h-version most frequently used, a p-version of the Orthogonal Collocation Method as applied to differential equations in two-dimensional domains is examined. For superior accuracy and convergence, the collocation points are chosen to be the zeros of a Legendre polynomial plus the two endpoints. Hence the method is called the Legendre Collocation Method. The approximate solution in an element is written as a Lagrange interpolation polynomial. This form of the approximate solution makes it possible to fully automate the method on a personal computer using conventional memory.

The Legendre Collocation Method provides a formula for …

Minimum Redundancy Array Structure For Interference Cancellation, Wan-Ling Chen

Dissertations

Adaptive antenna arrays are widely used in many advanced radar, sonar, and communication systems because of their effectiveness in cancelling intentional or unintentional interferers. A uniformly spaced linear array, referred to as a Uniform Regular Array (URA), is the usual structure used for interference cancellation. The Minimum Redundancy Array (MRA) structure proposed in this work is a special kind of thinned array whose application was limited in the past to direction finding. MRAs with the same number of array elements can resolve directions of much more closely spaced signals than URAs.

The URA structure is customarily utilized for interference cancellation, …

Tensile Behavior Of Concrete And Mortar Under Direct Impact Tensile Load, Kayumars Emad

Dissertations

Structures are often subjected to impact loadings during their lifetime. Most structural specifications including the special provisions for seismic design in the current ACI building codes, have been developed on the basis of quasi-static assumptions. Cement composites are strain rate sensitive materials therefore, their properties determined under quasi-static condition should not be used to predict their performance under high strain rates.

The objectives of this investigation are:

• to develop a standard test set-up for direct tensile testing of cementitious composites.
• to study the tensile behavior of mortar and concrete under direct impact tensile load.
• to develop a simplified formula to …

Characterization Of Advanced Etching Reactors Using Novel Diagnostic Tools, Vipulkumar Patel

Dissertations

Plasma etching equipment used for sub-micron integrated circuit fabrication at present are exclusively based on 13.56 MHz, capacitively coupled, parallel-plate geometry. The underlying mechanisms of plasma processes in these reactors are not well understood and there is even less understanding of how the etch-tool parameters relate to the plasma discharge characteristics which actually determine the etch process. In this thesis, new diagnostic techniques were applied for the characterization and optimization of plasma etching processes in various reactor configurations.

Specifically, diode and triode configurations were studied extensively using tuned scanning Langmuir probes. Both radial and axial distributions of plasma density were …

Kinetic Study Of Decomposition Of Azo Dyes And Phenol In Advanced Oxidation Processes Reaction Mechanisms, Pathways And Intermediates, Hung-Yee Shu

Dissertations

Advanced Oxidation Processes (AOP) are an emerging technology for treatment of various hazardous organics in wastewater and groundwater. However, the kinetics and mechanisms for AOP have not been well understood. A mechanism including light intensity was studied for the decomposition of azo dyes and phenol in an AOP reactor with a 5,000 watt low pressure mercury lamp. UV light absorption is an important parameter. The effect of pH, hydrogen peroxide dosage, and dye concentration on the decomposition of azo dyes in an H₂O₂/UV reactor were also studied. Reaction pathways and intermediates of phenol oxidation by different …

Unreinforced Masonry Structures : Nonlinear Analysis And Evaluation Of Some Rehab Schemes, Sanjay Mehta

Dissertations

Unreinforced masonry (URM) structures have been a common type of construction in the past and are still used in regions of low seismicity. Retrofitting of these structures is necessary because of two reasons: Firstly, observed damage after earthquakes reveals that URM construction is one of the most hazardous constructions even in the region of low seismicity; secondly, reclassification of seismic zones would require retrofitting of existing structures to comply with new guidelines for earthquake design.

Retrofitting measures require that the response of original and new structural systems as well as their interaction be considered. It is therefore important to correctly …

Utilization Of Fly Ash In Concrete, Chai Jaturapitakkul

Dissertations

Fly ash, a by-product of coal burning power plants, is produced in large quantities each year. It is commonly known that fly ash possesses pozzolanic behavior which can enhance the properties of concrete. Due to a lack of proper understanding on the formation of fly ash and its performance in concrete, the question of quality assurance has frequently been a major concern of engineers using fly ash in their construction projects. As a result, much fly ash is disposed of as waste material in landfills. Recent environmental concerns and a shortage of landfill space have rapidly escalated the disposal cost …

Competition Between Two Microbial Populations In A Sequencing Fed-Batch Reactor And Its Implications For Waste Treatment Applications, Sitaram Dikshitulu

Dissertations

Pure and simple competition between two microbial populations in a sequencing fed-batch reactor (SFBR) was studied both at the theoretical and experimental level. Competition occurred for a single chemical pollutant which could serve as the sole carbon and energy source for both competitors. A mathematical model describing the process under inhibitory kinetics (as is usually the case with hazardous and toxic substances) was derived and theoretically analyzed. The model predicts that the dynamics of a SFBR, and the kinetics of biodegradation, result in a complex set of operating regimes in which neither species, only one species, or both species survive …

Coordinate Measuring Machines : A Modern Inspection Tool In Manufacturing, Matthias Richard Mantel

Theses

Coordinate Measuring Machines (CMM) are flexible and universal dimensional measuring devices with the capability for full integration into a CIM information network. Developed as highly precise measuring machines for specially designed measuring rooms, today's CMMs are more and more used in shop floor applications which is a hostile environment for a precise measuring tool. CMMs are offered in a variety of configurations and levels of automation. For the CMM buyer it is therefore essential to have an overview of the different types of CMMs and their subsystems before making a purchasing decision.

To obtain reliable measuring results that are used …

Adaptive Two-Stage Detection Scheme In Synchronous Two-User Cdma Systems, Yong Jiang

Theses

A conventional single user detector is not optimum in the multiuser environment because the multiuser interference can not be modeled as an additive Gaussian process. Such a receiver is very vulnerable to the near far situation. The receiver that is optimum for multiuser environment has high complexity and requires a knowledge of the received signal energies. Various versions of the receiver that handle the near far situation have been proposed in the literature. In this work, an adaptive two stage scheme for a synchronous two user environment with unknown received energies is proposed. It consists of a, tandem of the …

A Review Of Acetabular Prostheses For Total Hip Arthroplasty, Jennifer Anne Citarella

Theses

This study explores the evolution, design, and clinical progress of contemporary prostheses used in orthopaedic reconstruction of the socket of the hip joint. A literature search was performed to study acetabular implants, as used in total hip arthroplasty. The history of the design of these implants is chronicled. Next, the anatomy of the acetabular region and the surgical technique performed to replace the hip socket are presented. A comprehensive discussion of the design features, rationale, and clinical results for commercially available cemented and cementless prostheses follows.

Hydroxyapatite, a bioceramic which has just recently been approved for applications in total hip …

Properties And Determination Of Optimal Decentralized Feedback Structure, Kangsong Han

Theses

In this thesis, the decentralized feedback structure for large scale, linear time invariant systems is studied. The internal differences and the relationship between decentralized feedback structure and centralized feedback structure are discussed. The conventional diagonal feedback structure. corresponding to the classical single loop design strategy, is first analyzed. This is followed by an arbitrary decentralized information flow constraint which is dependent upon the actual plant characteristics. Although signal flow graphs have limited use in describing decentralized control systems. the concept of a control cycle unit based on signal flow is introduced as a supplementary tool to characterize some fixed modes …

Polarimetric Fiber Optic Sensor For The Measurement Of Strain, Wei Ma

Theses

In this thesis, development of a Polarimetric Fiber-Optic strain sensor is presented. The sensor uses the phenomenon that strain can deform the probing part of the fiber and hence change the polarization of the transmitted light signal. By counting the resulting fringes, we can measure the exact strain in the material. Calibration of the sensor was achieved by setting up tension tests. Optical fibers were glued on the surface of the specimen. Reference strain gages were used to record the strain in the specimens. Resulting fringes from the fiber optic sensors were then related to the strain measured by the …

The Postbus Fault Tolerant Clos Network, Udayabhanu Sarangapani

Theses

The trend in modern computing is to develop multiprocessor systems with hundreds, even thousands, of processors and memory modules. The task of providing communication paths among all these units is not a trivial one. For a small number of functional units, direct connections could be used but for large systems interconnection networks have to be used. Multistage Interconnection Networks (MINs), provide a dynamic means for interconnecting processors and memory in a multiprocessor system. These networks are built with switches in each stage.

The Clos network is a well defined family of MINs and consists of three stages. The ordinary Clos …

Microengineered Mass Spectrometer With Field Emission Ionization Source, Chao Sun

Theses

This thesis describes a design for a microengineered mass spectrometer. This mass spectrometer device uses VLSI processing techniques to scale down the dimensions of an existing mass spectrometer and make it portable. It can be manufactured economically and has the potential to be integrated with more complex structures and including transistor integrated circuits. An optimized device is proposed. This device is to be fabricated using two silicon substrates approximately 1cm by 1cm, where one is a cathode electron source and the other is the ion collector. External ion sources are not needed. Electrons are emitted from the array of cathode …

Improving The Jitter Performance Of Timing Recovery By Employing Delay Shifts, Xin De Lu

Theses

Many methods have been developed for evaluating the jitter performance of timing recovery circuits for binary synchronous transmission systems. These circuits consist of a nonlinear device followed by a narrowband filter tuned to the pulse repetition frequency. This thesis introduce delay shifts in the timing recovery circuits to improve the jitter performance. The function of the delay shifts is analyzed and mathematical proof of jitter performance improvement is given for the system using square-law device. Finally, the numerical results obtained from the specific examples serve to illustrate the significant improvement between the system with and without delay shifts. That is, …

Investigation Of The Effects Of Methyl Chloride Addition On Premixed, Laminar, Methane/Air Flat Flames, Limin Wang

Theses

Temperatures and the concentrations of stable species, such as CO, CO₂, CH₄, and CH3Cl, have been measured over the height above burner at equivalence ratio of 0.79 (fuel lean) and 1.20 (fuel rich) for premixed, laminar CH₄/air and CH₃Cl/CH₄/air flat flames. A water-cooled quartz sampling micro-probe and gas chromatographic analysis were used for the concentration measurements. Chemical kinetic modeling of these flames with a 279-reaction, 63-species elementary reaction mechanism is performed using the CHEMKIN premixed flat flame code. The results of rate-of-production calculations are analyzed to determine the most important …

Modeling And Simulation Of Magnetic Micromotor Performance, Ping Wang

Theses

The objective of this research was to model the performance and optimize geometries for two types of magnetic micromotors: yoke-type (YTMM) and yokeless (YSMM). The two selected micromotor types matched the designs that have been described in the recent research literature. Modeling was accomplished using MAXWELL, an advanced 2-D and 3-D simulator. The micromotors with nickel and nickel-iron magnetic thin films for the rotor and stator were simulated for torque performance. Three-phase power supplies with overlapping and non-overlapping phases were used. Rotor diameter dimensions were varied from 285 to 600µm, and the rotor-stator air gap was varied from 3 to …

Modeling And Analysis Of Semiconductor Manufacturing Processes Using Petri Nets, Xinyao Wang

Theses

This thesis addresses the issues in modeling and analysis of multichip module (MCM) manufacturing processes using Petri nets. Building such graphical and mathematical models is a crucial step to understand MCM technologies and to enhance their application scope.

In this thesis, the application of Petri nets is presented with top-down and bottom-up approaches. The theory of Petri nets is summarized with its basic notations and properties at first. After that, the capability of calculating and analyzing Petri nets with deterministic timing information is extended to meet the requirements of the MCM models. Then, using top-down refining and system decomposition, MCM …

Modeling And Investigation Of Current Transport Phenomena In Schottky Structures, Yan Zeng

Theses

We have used a numerical method to describe the importance of the contribution of generation-recombination current to the I-V characteristics of Schottky barrier contacts. The current-voltage relationship is derived directly from the fundamental set of equations such as Poisson; current-density and continuity equations, without having to make many simplifications or approximations. The final result includes not only the thermionic emission or drift diffusion mechanisms of current flow, but also the generation recombination processes.

The experimental devices used for this work are very common low barrier height Schottky structures, Al/T_0.3W_0.7/n-Si/A1 and Ti_0.3W_0.7/n-Si/Al. The …

Integration Of Pneumatic Fracturing To Enhance In Situ Bioremediation, Conan Dante Fitzgerald

Theses

The purpose of this thesis was to study the anticipated benefits of integrating pneumatic fracturing with in situ bioremediation. Since pneumatic fracturing increases subsurface air flow in low permeability formations, it has the potential to overcome many of the major limiting factors of microbial growth and activity. A new innovation called pneumatic bio-injection can further enhance in situ bioremediation by efficiently dispersing biological solutions, including microorganisms, into a formation.

Bench scale experiments were conducted to examine the ability of microorganisms to survive the pressures and stresses associated with pneumatic injection. Tests conducted at pressures ranging from 60 to 500 psi …

A Multicompartmental Model For The Simulation Of Soluble Gas Exchange In The Lungs, Chitaranjan Varadhan

Theses

No abstract provided.

An Implementation Of A Versatile Camera Calibration Technique For High-Accuracy 3d Machine Vision Metrology Using Off-The-Shelf Tv Camera And Lenses, Bolang Li

Theses

This thesis studies and implements a new versatile camera calibration technique for high-accuracy 3D machine vision metrology using off-the-shelf TV camera and lenses developed by Roger Tsai [1]. This technique builds up a unique relationship from the world coordinate system to the computer image coordinate system of calibration points by using a radial alignment constraint. The technique has advantage in terms of accuracy, speed, and versatility over existing techniques.

The fundamental knowledge for using this technique is presented in this thesis first, followed by an overview of the existing calibration techniques, and a detailed description of the new technique. The …

Comparison Of Heart Rate With Chest Wall Vibrations, Kofi M. Arbuah

Theses

A study is done using a Microwave Interferometer as a computer-assisted non-invasive cardiopulmonary monitor. The Microwave Interferometer is used to record the mechanical vibration of the anterior chest wall by recording the velocity of the displacement of the chest wall. The objective is to first, record mechanical vibrations of the anterior chest wall at different heart rates, and second, attempt to identify the relation between heart rate and chest wall vibration.

The system uses two channels, the first signal produced by the Microwave Interferometer is a record of the velocity of the displacement of the chest wall caused by the …

Power Consumption In Single-Phase Agitated Vessels Provided With Multiple Impellers, Gwo-Ming Chang

Theses

A significant amount of data can be found in the literature on power consumption of single-impeller agitation systems. However, little and incomplete information is available for power consumption in multiple-impeller systems. Therefore, the main objective of this study is to experimentally determine the power consumed by multiple impellers in mixing vessels as a function of impeller type, impeller off-bottom clearance, impeller spacing, and agitation speed.

In this work, the power dissipated by combinations of one, two or three impellers of either identical types or different types was studied. The power drawn by each individual impeller was measured by means of …

A Mathematical Model For The Prediction Of Depth Of Cut In The Course Of Awj Machining, Naijian Ma

Theses

The objective of this study is to develop a practical mathematical model for prediction of the depth of cut in the course of Abrasive Water Jet (AWJ) machining. Semi-empirical method which is an integration of theoretical derivation and statistical analysis is used for process description. A theoretical model was constructed based on kinetic energy conservation equation, physical relationship among operating parameters, abrasive size, material properties and cutting results. Then, correlation between the depth of cut and operational parameters was analyzed in order to improve the theoretical model. Finally, a regression equation representing 1000 samples was constructed.

Three statistical criteria were …