Engineering Commons^™

Turbulent Mixing And Chemical Reaction In Baffled Stirred Tank Reactors : A Comparison Between Experiments And A Novel Micromixing-Based Computational Fluid Dynamics Model, Otute Akiti

Dissertations

The optimization of reaction processes to maximize the yield of a desired product while minimizing the formation of undesired by-products is one of the most important steps in process development for drug manufacturing or fine chemical production. In many situations the kinetics of product formation can be quite complex and involve a number of intermediate steps as well as parallel and serial reactions. This renders the systems sensitive to the operating conditions. Often, upon scale-up, a decrease in the yield of the desired product is experienced, while more undesired by-products are produced. A large number of interrelated variables influence the …

Feasibility Study To Extract Iron And Chromium From Chromium Contaminated Soils, Wiwat Kamolpornwijit

Dissertations

Chromium contaminated soils, besides being recognized for toxic and hazardous hexavalent chromium, contain high iron concentrations. At some sites, concentrations of iron oxide are higher than 30%. Both iron and chromium in soils have recyclable value provided they can be either concentrated in the oxide form or separated as metal. The concentrated oxide can be used as a substitute for the iron ore. The extracted metal can also be recycled in the steel industry. The objective of this study is to study the feasibility of extracting iron and chromium from soils.

Chromium contaminated soils, can be classified into two groups, …

Axisymetric Vibrations Of Homogeneous And Sandwich Spherical Shells With A Hole At The Center, Wai-Kwong Wong

Dissertations

Based on Hamilton's principle and the theory of elasticity, both linear and nonlinear governing equations of motion are derived for elastic spherical shells. Most of the analysis is focused on the free axisymmetric vibrations of homogeneous and sandwich shallow spherical shells. The nonlinear behavior, which allows for small deflections, is also discussed.

The linear vibrations of homogeneous and sandwich shallow spherical shells with a hole at the center are investigated with emphasis placed on the effect of thickness-shear deformation and rotatory inertia. The effects of curvature and the size of the central hole are studied for free axisymmetric motions of …

Nanoporous Sio2/Vycor Membranes For Air Separation, Mihir Tungare

Theses

Porous Vycor tubes with 40Å initial pore diameter were modified using low pressure chemical vapor deposition (LPCVD) of silicon dioxide N0₂). Diethylsilane (DES) in conjunction with nitrous oxide (N₂O) was used as a precursor to synthesize these SiO₂ films. The aim of this study was to obtain a considerable selectivity between species of comparable size and hence N₂O was used. The use of N₂O was believed to make the process self-limiting. DES was allowed to flow through the tube and N₂O on the outside in the chamber at 550°C …

Reduction Of Peak To Average Power Ratio In Ofdm And Ofdm-Cdma System, Jie Cheng

Theses

High Peak to Average Power Ratio is a main problem in Orthogonal Frequency Division Multiplexing(OFDM) system and Orthogonal Frequency Division Multiplexing -Code Division Multiple Access (OFDM-CDMA) system. Considering a compensated High Power Amplifier(HPA), in order to keep linearity for amplification, Input Back-Off(IBO) of the HP-A, has to be increased for handling a high PAPR. Higher 1130 will make HPA less efficient. Additionally, a signal with high PAPR will suffer clipping when PAPR is larger than 1130 of the HPA. Clipping can cause the distortion of the signal and deteriorate the performance of the system. Reduction of PAPR is a main …

Autonomic Activity In Gulf War Veterans Using Heart Rate And Systolic Blood Pressure Variability, Maryann S. Fam

Theses

Heart rate variability (HRV) describes variations of heart rate and is attributed to cyclic fluctuations in autonomic tone. The different methods of heart rate variability analysis allow for a non-invasive assessment of autonomic activity. This study analyzes the heart rate variability through both frequency domain methods and joint time-frequency domain methods which were executed through the LabVJEW graphical programming language. These algorithms were utilized to assess autonomic nervous system activity in Gulf War veterans with no health complaints versus Gulf War veterans with chronic fatigue syndrome. The heart rate variability analysis was obtained from acquired measurements of heart rate and …

Drowsy Driver Data Acquisition System, Rafael Norat

Theses

This thesis focuses on detecting the drowsiness of a driver based on differentiation of the EEG signal activity between the eyes open and eyes closed states. Here, it is observed that there is a significant increase 'in a 10 Hz component of the alpha rhythm activity when the subject under test closes his / her eyes. This phenomenon was observed when electrodes were attached to the occipital region. A more desirable approach is to develop a non-intrusive measurement based on a multiturn differential coil combination utilizing a low noise high gain amplifier. The system developed here used an 80,000 turn …

Phase Tunability In A Conductor Backed Coplanar Waveguide Patch Antenna, Idan Mandelbaum

Theses

Traditionally beam steering in phase array antenna systems is achieved using tunable phase shifters or switched feed networks. Here, a tunable patch antenna element is suggested as a novel alternative to a combination of a radiating element and a phase shifter. A conductor backed coplanar waveguide patch antenna is chosen due to its suitability to mounted external tuning elements, using varactor diodes. Limited types of lumped tuning circuits, using varactor diodes, have been tested, though a lumped as well as distributed tuning is feasible in the chosen antenna configuration. Approximate analytical models for coplanar waveguide patch antennas with finite ground …

Nanofiltration-Based Diafiltration Process For Solvent Exchange In Pharmaceutical Manufacturing, Jignesh P. Sheth

Theses

Commercially available solvent stable polymeric nanofiltration membranes were used to study the nanofiltration and diafiltration operations in the context of the pharmaceutical industry. Experimental results are presented for a two-step operation involving the preconcentration of a feed solution via nanofiltration followed by the replacement of the first stage solvent with a second solvent via diafiltration in two stages. Membranes MPF-50 and MPF-60, having molecular weight cut-offs of 700 and 400 respectively, were used in the present study. A solution of erythromycin (MW 734) in ethyl acetate was preconcentrated via nanofiltration followed by replacement of ethyl acetate with methanol via batch …

Preparation And Properties Of Tantalum Silicide Films On Silicon Substrates, Lei Jin

Theses

Tantalum silicide (TaSi₂) thin films were sputter deposited on p- type and n- type silicon substrates using VARIAN 3125 magnetron DC sputtering system with TaSi₂ target. The thicknesses of TaSi₂ thin films considered in this study are 200Å, 600Å and 1000Å, respectively. The TaSi₂/Si wafers were annealed at temperatures in the range of 400 to 900°T. The sheet resistances of TaSi₂ thin films with various thicknesses were measured by four-point probe before and after annealing. The sheet resistance decreases with increase in annealing temperature and decreases with the increase in thickness of TaSi …

Intermodal Transit System Coordination With Dynamic Vehicle Dispatching, Md. Shoaib Chowdhury

Dissertations

In most urban areas where transit demand is spread widely, passengers may be served by an intermodal transit system, consisting of a rail transit line (or a bus rapid transit route) and a numbers of feeder routes connecting at different transfer stations. In such a system, passengers may need one or more transfers to complete their journey. Therefore, scheduling vehicles operating in the system with special attention to reduce transfer time can contribute significantly service quality improvements. In this study two models, one for coordination of a general intermodal. transit system and another for dynamic dispatching of vehicles on coordinated …

Multimedia Modeling Of Organic Contaminants In The Passaic River Watershed, Lansana Coulibaly

Dissertations

A dynamic fate and transport multimedia environmental model was developed and applied to assess the release of five priority contaminants in the Passaic River Watershed, including: napthalene, toluene, trichloroethylene, 1-1-1 trichloroethane and xylene. The model uses the current releases of contaminants as well as cross-boundary advection to determine the fate and environmental distribution of these chemicals in the watershed. The model was developed using a dynamic fugacity approach in order to allow for scenario analysis such as source reductions and no-action alternatives. This modeling effort is expected to achieve a comprehensive assessment of contaminants not only in the proximity of …

The Impact And Fate Of Aqueous Sodium Nitrate On Hydrocarbon Flames, Ann Marie Flynn

Dissertations

This study examined the impact and fate of sodium (fed as an aqueous nitrate solution) in fuel-rich methane/air and methane/methyl chloride/air flames as a function of equivalence ratios that experienced diffusion of air from the surroundings. The flames were stabilized on a slotted, uncooled burner. The data set was divided into profiles of relative sodium atom concentrations, temperatures, and selected stable species concentrations. The flames were simulated using a modified version of the Sandia FORTRAN program for modeling steady laminar one-dimensional premixed flames complete with detailed mechanisms. The results showed that maximum sodium atom concentration in the flame is decreased …

Endotoxin Removal From Protein Solutions By Immobilized Metal Ion Affinity Chromatography, Yun Kang

Dissertations

In the biotechnology/pharmaceutical industry, the removal of endotoxins from final protein product has always been a challenge. A novel method for endotoxin removal from protein solutions, immobilized metal (ion) affinity chromatography (IMAC) has been developed in this study. Fe³⁺ was charged to a chelating gel that contains iminodiacetic acid (IDA). The IDA- Fe³⁺ IMAC column was exploited to remove endotoxin from protein solutions. This method involves the adsorption of the endotoxin on IMAC column. More than 99% endotoxin is removed and protein yield is higher than 90%. IDA-Fe³⁺ IMAC has proved to be an economical and efficient …

Video Traffic Modeling And Delivery, Hai Liu

Dissertations

Video is becoming a major component of the network traffic, and thus there has been a great interest to model video traffic. It is known that video traffic possesses short range dependence (SRD) and long range dependence (LRD) properties, which can drastically affect network performance. By decomposing a video sequence into three parts, according to its motion activity, Markov-modulated self-similar process model is first proposed to capture autocorrelation function (ACF) characteristics of MPEG video traffic. Furthermore, generalized Beta distribution is proposed to model the probability density functions (PDFs) of MPEG video traffic.

It is observed that the ACF of MPEG …

Fluidization And Soot Filtration In A Rotating Fluidized Bed, Gui-Hua Qian

Dissertations

A horizontal rotating fluidized bed (RFB) has been investigated for the removal of soot from diesel engine exhaust. This requires necessitating an understanding of the nature of fluidization, particle mixing and filtration in the RFB.

In an RFB, particles are subject to a centrifugal force which can be much larger than the force of gravity. Therefore the Geldart classification for conventional fluidized beds must be modified for rotating fluidized beds. A theoretical analysis shows that group A particles (minimum bubbling velocity U_mb > minimum fluidization velocity U_mf can shift to group B U_mb = U_mf and group …

Virtual Reality Based Creation Of Concept Model Designs For Cad Systems, Bilal Yehya Maiteh

Dissertations

This work introduces a novel method to overcome most of the drawbacks in traditional methods for creating design models. The main innovation is the use of virtual tools to simulate the natural physical environment in which freeform. Design models are created by experienced designers. Namely, the model is created in a virtual environment by carving a work piece with tools that simulate NC milling cutters.

Algorithms have been developed to support the approach, in which the design model is created in a Virtual Reality (VR) environment and selection and manipulation of tools can be performed in the virtual space. The …

Investigation Of The Baroreflex Of The Rat : Steady State And Dynamic Features, Xiaorui Tang

Dissertations

The baroreflex is one of the most important feedback systems in the body to maintain blood pressure variation within the homeostatic range. In this dissertation, the important features of the carotid and aortic baroreflexes have been extensively investigated on ventilated, central nervous system intact, neuromuscular blocked (NMB) rats using different control system and signal processing tools. Studies have demonstrated that sinoaortic denervation (SAD) caused substantial increases in the blood pressure variability. Comparing the pre- and post-SAD blood pressure spectra, there was a significant increase of power in the very low frequency region (0.00195 -0.2 Hz), and a significant decrease of …

Rapid Tooling By Integration Of Solid Freedom Fabrication And Electrodepostion, Bo Yang

Dissertations

Rapid tooling (RT) techniques based on solid freeform fabrication (SFF) are being studied worldwide to speed up the design-production cycle and thus keep manufacturers at a competitive edge. This dissertation presents a novel rapid tooling process that integrates SFF with electrodeposition to produce molds, dies, and electrical discharge machining (EDM) electrodes rapidly, accurately and cost effectively. Experimental investigation, thermornechanical modeling and analysis, as well as case studies reveal that integration of electroforming with solid freeform fabrication is a viable way for metal tool making.

The major research tasks and results of this dissertation study are as follows:

• Rapid electroforming tooling …

Laminar Viscous Resuspension In Two-Dimensional Channels, Wenyue Yin

Dissertations

The laminar viscous resuspension of sphere particles in two-dimensional channel with gravity and electrostatic effects is studied numerically. The constitutive equation for particles include the shear-induced diffusion flux, gravitational sedimentation flux and electro-static diffusion flux. In addition the continuity equation and the momentum equations for incompressible flow are solved for developing flow using finite element method.

The parameters in this study are ratio of particle diameter to channel height d/h, Reynolds number Re, Froude number Fr, uniform inlet particle volume fraction Φ₀, and electrostatic parameter Q. The numerical simulation included d/h from 0.03 to 0.12, Re from 5 …

An Integrated Membrane-Based Chromatographic Process For Biomolecule Isolation And Purification, Xiaoping Dai

Dissertations

Biomolecules obtained from fermentation and cell-culture processes are present in low concentrations in a complex medium/broth. For intracellular products, cells are first harvested. Subsequently, cell lysis and homogenization are undertaken to produce a homogenate. The biomolecules are next separated from the cell debris by lysate clarification. For extracellular products, the biomolecules are separated from the whole cells by clarification. The overall yield is reduced with each additional step. As the cost of bioseparation process accounts for 50-80% of the final product cost, innovations in and improvement of bio-downstream processing are greatly needed.

In this research, a cyclic process integrating a …

Simulation And Modeling Of Magnetically-Assisted Impaction Coating (Maic) Process For Dry Particle Coating, Bodhisattwa Chaudhuri

Dissertations

The objective of proposed research is to model, and understand the processes happening at multiple length and time scales in magnetically assisted impaction coating process. The smallest length scale is of the order of the molecular size and is important because during collisions the molecules rearrange themselves to form a semi-permanent bond between the core and secondary particles, which is studied by using the results of direct numerical integration of the governing Newton's equations. The effect of parameters such as size, orientation and relative velocity of particles on the collision mechanics is quantified. The largest length scale which is the …

Design And Analysis Of A Scalable Terabit Multicast Packet Switch : Architecture And Scheduling Algorithms, Feihong Chen

Dissertations

Internet growth and success not only open a primary route of information exchange for millions of people around the world, but also create unprecedented demand for core network capacity. Existing switches/routers, due to the bottleneck from either switch architecture or arbitration complexity, can reach a capacity on the order of gigabits per second, but few of them are scalable to large capacity of terabits per second.

In this dissertation, we propose three novel switch architectures with cooperated scheduling algorithms to design a terabit backbone switch/router which is able to deliver large capacity, multicasting, and high performance along with Quality of …

Synthesis And Characterization Of Low Pressure Chemically Vapor Deposited Boron Nitride And Titanium Nitride Films, Narahari Ramanuja

Dissertations

This study has investigated the interrelationships governing the growth kinetics, resulting compositions, and properties of boron nitride (B-C-N-H) and titanium nitride (Ti-N-Cl) films synthesized by low pressure chemical vapor deposition (LPCVD) using ammonia (NH₃)/triethylamine-borane and NH₃/titanium tetrachloride as reactants, respectively.Several analytical methods such as the FTIR, UVNisible spectroscopy, XPS, AES, RBS, SEM, and XRD were used to study the stoichiometry and structure of the deposited films.

The B-N-C-H films were synthesized over a temperature range of 300 to 8500C at various flow rate ratios of the reactants and total pressure range of 50 to 150 mTorr. …

Interaction Of A Vortex Pair And A Free-Surface : Numerical Simulation, Haisheng Ruan

Dissertations

The interaction between a submerged vortex pair with a deformable free-surface in a viscous, incompressible fluid is directly simulated and the flow is thoroughly analyzed. This is a time-dependent nonlinear free-surface problem which we solve numerically by integrating the two-dimensional Navier-Stokes equations and using boundary-fitted coordinates capable of handling large free-surface deformations. In particular, the numerical simulation of the flow at relatively high Reynolds numbers (Re = 500,1000, 2000 ) and relatively high Froude numbers (Fr = 1. 125, Fr = 2.0) is investigated and analyzed for the first time. Details are given regarding the space-time deformation of …

Design And Fabrication Of Optical Resonators, Pushkar Moholkar

Theses

The design and fabrication of ring optical resonators for high-speed optical communication systems is the topic of this thesis. Its novelty is in two aspects: 1) Use of silicon wafers as an optical guiding medium; 2) Use of wafer bonding technique to attach two optical elements together.

The structure consists of two optical waveguides, the bus waveguide and the drop channel waveguide. A ring on top of these waveguides couples them in such a way that only one narrow spectral line is removed from the bus waveguides which propagates in the drop-channel waveguide. The assembly is fabricated using wafer-bonding technique …

Biomechanical Evaluation Of Patient Transfers, Charles Costa

Theses

The purpose of this study is to identify the problem encountered when a patient with limited strength and mobility needs assistance in transferring from a wheelchair to another location.

This study took advantage of ergonomic techniques to isolate the source of stress, and limited these stresses according to the standards of the National Institute of Safety and Health Administration.

A device was developed whereby the stresses of a patient transfer were eliminated. By using a conventional wheelchair and a recliner as a starting point, effectively combining these components into a single multifunctional unit the goal of reducing stress was achieved. …

Numerical Studies Of Deep Bed Filtration, Chan-Gyun Shin

Theses

Deep bed filtration is a process used to separate small solid particles suspended in a fluid by using granular solids as the collecting medium. The filter efficiency depends on many parameters such as the Reynolds number, particle drag coefficient, the ratio of the diameter of injected, and filter particles, etc.

In the present work we model the porous media flow (solution of the Navier-Stokes equations) by using a computer code developed by Dr. P. Singh and we restrict our analysis to the case of two dimensional periodic porous media. The computational domain is discretized using the finite element method. In …

Current-Voltage Characteristics Of Tasi2/Si And Mos Devices Using Labview, Prasant Tangirala

Theses

Analyses of current-voltage (LV) characteristics of Schottky Barrier Diodes (Tantalum Suicide) and Metal Oxide Semiconductor (MOS) Devices, using LabVIEW^TM, has been presented here. LabVIEW^TMTM, a graphical program development application, has been used to program a computer-driven Keithley Source Measure Unit (SMU) for device characterization. The SMU, which can be used as a Source Voltage - Measure Current as well as Source Current - Measure Voltage instrument, is used in the Source Voltage -Measure Current mode in this study. A General Purpose Interface Bus (GPIB) IEEE 488.2 has been used to interface the SMU with LabVIEW^{TM …}

Development Of A Demanufacturing System Modeling And Simulation Tool, Jingjing Hu

Theses

This thesis develops a demanufacturing system modeling and simulation tool as an interface between simulation methods and demanufacturers. This tool can mimic the behavior of demanufacturing facility and obtain penetrable understanding of the system. By this modeling tool, one can intuitively analyze the behavior of a system and improve the operational efficiency. Detailed designs on the simulation tool including user interface, logic, and user view are presented in this thesis. The initial prototype version of the system modeling and simulation tool has been completed with fourteen modules in the developed template. Each object in the template refers to a specific …