Engineering Commons^™

Ab Initio Calculation Of Electronic And Optical Properties Of Beryllium Chalcogenides (Bes, Bese, And Bete) Under The Effect Of Pressure, Aisha Ali Saif Bannan Al-Kaabi

Theses

There are several methods for materials simulation. Ab initio or first principles methods are used to solve the quantum mechanical equation which govern the behavior of a system. Ab initio calculation of the optical and electronic properties of solids is fundamental in solid state physics. APW+lo is used to examine different properties of BeS, BeSe and BeTe. Beryllium compounds show different features in structure under different pressures, and they also show a phase transition from Zinc blende to Hexagonal transitions in II-VI semiconductors. Little is known about the ground state properties of Beryllium Chalcogenides. The aim of this work is …

Stabilization Of Desert Sand Using Water-Borne Polymers, Shihab Wagiealla Abdalla Mohamed

Theses

Soil stabilization is one of the various applications that have benefited from the advances in polymeric materials. In this research, three water-borne polymeric emulsions with different chemical and physical properties were tested as stabilizers for sandy soil.

This study is divided into three parts. In the first part, the performance of the three emulsions in reducing the hydraulic conductivity and improving the mechanical properties of the sand was investigated. Specimens with polymer contents of up to 2 wt. % were prepared using two preparation methods, mixing and spraying. Both types of specimens exhibited a significant improvement in the studied properties. …

Carrier Transport In Ge Nanowires And One Dimensional Si/Ge Heterojunctions, Eun Kyu Lee

Theses

Ge Nanowires (Ge NWs) on single crystal, (100) and (111) oriented n-type Si substrates were grown via the vapor-liquid-solid (VLS) mechanism and studied with respect to their electrical properties.

Using different contact geometries, direct current (DC) and alternating current (AC) electrical and photoelectrical measurements were carried out at room temperature to investigate electrical properties of Ge NWs and Ge NWs/Si substrate one-dimensional (1 D) heterojunctions (HJs). A rectifying junction behavior is observed at NWs/substrate interface, but many orders of magnitude greater AC conductance than DC in Ge NW volume is measured at high frequencies. The obtained experimental data are consistent …

Characterization Of Mechanical Behavior Of Electrospun Non-Woven Mats, Ajitha Patlolla

Theses

Electrospinning is a simple and efficient method for the production of nanometer to micrometer fibers. While the process of electrospinning has been known for over half a century, current understanding of the process and those parameters that affect the properties of the fibers is very limited. Not much work has been done in the field electrospinning process to study the mechanical properties of nonwoven mats produced and to study parameters affecting their properties.

In the first part of this thesis electrospun nonwoven mats made of poly(lactides) solutions were characterized based on their mechanical behavior in biorelevant conditions. In the second …

Fluidization Of Agglomerates Of Nanoparticles Under Different Force Fields, Jose A. Quevedo

Theses

Nanoparticles are the focus of many research activities, and in the near future they will be handled in large amounts by industry. Fluidization is a very important unit operation which is applied in several industrial processes.

In the present work, fluidization experiments with agglomerates of nanoparticles were done under different force fields: (1) gravity force or conventional fluidization; (2) a magnetic force field, which uses magnetic particles under the influence of a magnetic field; and (3) a centrifugal force, generated by a rotating frame that simulates higher gravity conditions.

Among the significant results with agglomerates of nanoparticles, conventional fluidization was …

Spectrum Control And Iterative Coding For High Capacity Multiband Ofdm, Divaydeep Sikri

Theses

The emergence of Multiband Orthogonal Frequency Division Modulation (MB-OFDM) as an ultra-wideband (UWB) technology injected new optimism in the market through realistic commercial implementation, while keeping promise of high data rates intact. However, it has also brought with it host of issues, some of which are addressed in this thesis.

The thesis primarily focuses on the two issues of spectrum control and user capacity for the system currently proposed by the Multiband OFDM Alliance (MBOA). By showing that line spectra are still an issue for new modulation scheme (MB-OFDM), it proposes a mechanism of scrambling the data with an increased …

Ultra Wideband Communication Link, Preeti Singh

Theses

Ultra-wideband communication (UWB) has been a topic of extensive research in recent years especially for its short-range communication and indoor applications. The preliminary objective of the project was to develop a description and understanding of the basic components of the communication link at microwave frequencies in order to achieve the primary objective of establishing a communication setup at a bandwidth of 2.5 GHz for testing Ultra Wideband (UWB) antennas. This was achieved with the aid of commercially available optical system which was modified for the purpose. Beginning with the generation of baseband narrow pulses with energy spanning over a broad …

Surface Treatment Of Ferrous Alloys With Boron, Naruemon Suwattananont

Theses

Boronizing is a thermo-chemical surface hardening treatment in which boron atoms diffused into the metal substrate form the metallic boride layer, providing high hardness, corrosion resistance, and 3-10 times increasing service life. This type of surface treatment is widely used in many applications.

The purpose of this work was to investigate the structures and properties of boronized ferrous alloys. Three types of steels, AISI 1018 (plain low carbon steel), AISI 4340 (high strength alloy steel), and AISI 304 (austenitic stainless steel), were used for this study. The boronized AISI 1018 and AISI 4340 demonstrated the saw-tooth structure with average 75-76 …

Thermal Analysis Of Poly(Desamino Arylates), Ali Cem Recber

Theses

The goal of this study is to better understand the thermal characteristics and molecular behavior of two poly(desaminotyrosyl arylates). These two polymers were chosen from a combinatorial library of polymers developed by changing the type and size of the two substitutable chain locations. TGA, DSC and TSC studies were conducted on Poly(12,10) and Poly(2,2) after the samples were exposed to various conditions. The TGA of Poly(12,10) shows low water uptake at 25° C, higher water uptake at 80°C. Water uptake for Poly(2,2) at 25°C is similar to Poly(12,10) at 80°C. The Thermally Stimulated Current analysis (TSC) results indicate a molecular …

Detection Of Denial Of Service Attacks Using Database Queries, Dmytro Zakhalyavko

Theses

In the current intrusion detection world, most intrusion detection systems output data into flat files. This project was conducted in order to improve intrusion detection data and alerts by writing them into a database system and analyzing them with SQL. A database plug-in was developed that helps to transition the data from an intrusion detection system to a database. Storing, analyzing, categorizing, and accessing data are major advantages and reasons for using databases in intrusion detection. Security analysts have to constantly perform the difficult task of sorting through a haystack of attack alerts, many of which turn out to be …

Crystallization Kinetics Study Of The Glasses In Se–Te System, Fareed Abdul Raheem Al-Gheyath

Theses

The aim of the present work is to study the crystallization kinetics of some chalcogenide glassy alloys in the Selenium-Tellurium system. Four glassy systems have been prepared: Se₈₀Te_20-xSb_x (x= 0, 4, 6, 8, and 10); Se₇₀Te_30-xSb_x (x= 2, 6, 8, and 10); Se₈₀Te_20-xCd_x (x= 2, 4, and 10); and Se₈₀Te_20-xSn_x (x= 2, 4, and 10). The starting materials of (99.999%) purity were weighted according to their atomic percentages and sealed in evacuated silica tubes, under a pressure of about 10 …

Rehabilitation Of Concrete Structure Using Composite Materials, Ibtesam J.Saeed Al-Saifi

Theses

In the United Arab Emirates, most of the concrete structures including road, infrastructure and different types of buildings have been reported to be in need of rehabilitation. It is universally acknowledged that the environment of the countries in the Arabian Gulf is extremely severe and very aggressive to construction materials and operations. It is anticipated that the cost of rehabilitation of civil infrastructure will gradually increase over the next decade as a direct consequence of the increase in the number of structures reaching their expected service life.

Accordingly demand on rehabilitation methods will increase. In addition the severe climatic conditions …

A Statistical Ultra Wideband Indoor Channel Model And The Effects Of Antenna Directivity On Multipath Delay Spread And Path Loss In Ultra Wideband Indoor Channels, Jason Anthony Dabin

Theses

Ultra-wideband (UWB) indoor frequency domain channel measurements have been performed in the 2 GHz to 6 GHz frequency band using three different transmitter/receiver (Tx/Rx) antenna combination pairs. The effects of antenna directivity on path loss and multipath propagation in the channel were analyzed extensively for various omni-directional and directional antenna combinations. A statistical model of the path loss in the channel is presented, where the parameters in the model (i.e., path loss exponent and shadow fading statistics) are dependent on the particular Tx/Rx antenna combination. Time domain statistics of the channel (i.e., mean delay spread and RMS delay spread) are …

An Investigation Of Position And Force During Gait-Mimicking Finger Motions, Matthew Stephen Noesner

Theses

Spinal cord injuries are extremely debilitating, often leaving the injured person without the ability to use their legs (paraplegia) and sometimes, without the ability to use their arms and legs (tetraplegia or quadriplegia). Currently, primitive forms of feed-forward functional electrical stimulation (FES) and special orthotics are available for persons with paraplegia. However, these forms of FES do not allow the individual to actually control their movements on a real-time basis, nor do they offer the ability for the injured person to sense the ground on which they stand.

It is the goal of the researchers at the Neuromuscular Engineering Laboratory, …

Human Factors Approach Towards Improving Readability Of Bus Schedules, Anand Tharanathan

Theses

Due to an increasing concern over the readability of existing bus schedules of a public transportation agency the schedule format was redesigned. Two prototype schedules were designed based on the gathered information from the literature survey, focus group meetings and data from other public transportation agencies' schedules. One of the prototypes was designed by giving primary importance to the direction of travel and was named the directional prototype schedule. The other prototype was designed by giving primary importance to the day of the week, and was named weekday / weekend prototype schedule. A time based laboratory experiment and a subjective …

Case Studies In Disassembly Process Planning, Riteshkumar Dhimmar

Theses

The rapid advancement in technology started in last century and still continuing resulted in decreased life cycle of electronic products. It also resulted in increased product disposal rate and filling land fill space faster causing shortage of such space and consequently creates major environmental problems. So, since couple of decade environmental concern has focused on production process and environmental regulations imposed by government has watched industrial pollution. With government regulations to control environmental problems; consumers are also aware of adverse effects of product disposal forcing manufacturer to become more responsible for safe product disposal and recycling of used product.

A …

Design And Implementation Of Heart Rate Variability Measures In The Time Domain, Binoy John Mathews

Theses

The following study was conducted to design and implement computer programs to derive five time domain and two frequency domain Heart Rate Variability (HRV) measures from 24 hour Holter monitor recordings and to generate activity plots that display the variation of three of the five time domain measures and two frequency domain measures over a period of 24 hours.

Working with known pre and post experimental ECG data taken from a cyclical exercise program, standard parameters in both the time and frequency domains were derived using programs designed in Labview 7.0 engineering software package. Five parameters in the time domain …

Voice Onset Time Variation In Stop Consonant To Vowel Transitions, Abhishek Gunvant Parikh

Theses

Reduced duration, increased consistency, and improved intelligibility are goals of reducing the motor complexity of speech for individuals with cerebral palsy having dysarthria. In this study, measurement and analysis were made to compare an individual with spastic Cerebral Palsy (CP) having dysarthria to an individual with athetoid CP having dysarthria as well as to a non-dysarthric individual. Each participant's normal speech, whispering, and speech using an artificial larynx was evaluated, utilizing the source-filter theory methodology. The plausibility of dysarthric speech duration reduction by minimizing vocalization is tested by stop consonant "P,, to vowel transitions. The data suggest that speech duration …

Extending The Boundary Method For Solving Human Motion Problems Using A 3 Dimensional Coupled Pendulum Model, Avani Janardan Patel

Theses

Mathematical modeling, an evolving area in movement analysis research, couples quantitative measures of human motion with theoretical concepts in physiology and mechanics. Literature reveals two methods to solve for human motion problems, Forward and Inverse Mechanics. In this investigation, a new approach called the Boundaty Method is adopted to solve for human motion. This approach has the advantage of being able to solve for both new motions and the net muscular joint forces required to produce those motions but only at those discrete times and body configurations that are believed to be most crucial for accomplishing the task.

The method …

Evaluation Of Effect Of Extrusion Process Variables On Mechanical Properties Of Extruded Collagen Tubes And Effect Of Post Extrusion Treatments, Mayank K. Patel

Theses

This study evaluated the effect of extrusion process variable on mechanical properties of extruded collagen tubes made using a specialized extruder, made by ZOKO Corporation of Czechoslovakia. Three extrusion variables were considered; extrusion speed, linear draw rate and rotation speed. Using Taguchi L₄ matrix, a design of experiment (DOE) was run. Two mechanical properties, wall thickness and estimated elastic modulus, were considered as response of this DOE. Data was analyzed statically to evaluate the effect of extrusion variables on both these properties. Result of this study showed that linear draw rate of the extrusion process has the highest influence …

Biomimetic Sensor For In-Vivo Applications, Daya I. Sooryadas

Theses

The development of sensitive specific devices (e.g., molecular sensors) for the detection, diagnosis and monitoring of diseases, drug discovery, environmental detection of pollutants and/or biological agents has been an active area of research. A molecular sensor is a biomolecule or biomimetic molecule that performs two distinct functions in detecting target molecules. The sensor molecule recognizes a target molecule and specifically binds to it. This specific binding generates a signal in response to the event of target binding that can be then detected. The long term vision of this thesis research work is to develop a specific recognition ligand for detecting …

Simulation Analysis Of Anti-Rollover Mechanism For Vehicles, Mohib L. Raid

Theses

Rollover accidents are considered the most significant safety problems for all classes of light vehicles, especially pickups, Sport Utility Vehicles (SUV), Light Truck Vehicle (LTV) and vans. The main objective of the research is the design of a new mechanism able to keep the vehicle stable under various road conditions and high speeds, to prevent the vehicle from rolling over and to maintain the stability for the vehicle by creating an anti-rolling torque on the vehicle body capable of turning the vehicle smoothly to stable position.

Measurement Of The Effectiveness Of Enhanced External Counterpulsation On Heart Rate Variability For Patients With Myocardial Ischemia, Kripa Jayaraman

Theses

This thesis is a study to measure the changes in heart rate variability due to the activity of the autonomic nervous system caused by the Enhanced External Counterpulsation treatment. The treatment is a non surgical, mechanical procedure that can reduce the symptoms of angina or Congestive Heart Failure, presumably by stimulating the opening, or formation of, small branches of blood vessels (collaterals) to create a natural bypass around narrowed or blocked arteries. It has been proved that rhythms can be markers of normal functional states. Even in the absence of external perturbations, the normal heartbeat is not characterized by clockwise …

Parametric Synthesis Of Sign Language, Jerome Allen

Theses

The isolation of the deaf community from mainstream society is in part due to the lack of knowledge most hearing people have of sign language. To most, there seems to be little need to learn a language that is spoken by such a small minority unless perhaps a relative is unable to hear. Even with a desire to learn, the task may seem insurmountable due to the unique formational and grammatical rules of the language.

This linguistic rift has led to the call for an automatic translation system with the ability to take voice or written text as input and …

Mathematical Modeling And Simulation Of Human Motion Using 3-Dimensional, Multi-Segment Coupled Pendulum System : Derivation Of A Generalized Formula For Equations Of Motion, Loay Ahmed-Wasfe Al-Zube

Theses

The use of mathematical models to investigate the dynamics of human movement relies on two approaches: forward dynamics and inverse dynamics. In this investigation a new modeling approach called the Boundary Method is outlined. This method addresses some of the disadvantages of both the forward and the inverse approach. The method yields as output both a set of potential movement solutions to a given motor task and the net muscular impulses required to produce those movements. The input to the boundary method is a finite and adjustable number of critical target body configurations. In each phase of the motion that …

Application Of Bootstrap Resampling In Fmri, Arthika Bappal

Theses

This thesis demonstrates the use of the bootstrap resampling technique considering temporal dependency in the fMRI data to determine the reliability and confidence interval of fMRI parameters. Traditionally, the test-retest method has been used to reliably detect active voxels in the fMRI image of the brain, which is based on repetitive experimentation. The main concern with the test-retest method is the reproducibility of data over these multiple repetitions. Fatigue, habituation, motion artifacts, and repositioning errors are few of the factors, which can affect the reproducibility of data.

The conventional bootstrap resampling technique is based on the assumption that the dataset …

Effects Of Sleep Deprivation On Autonomic Nervous System, Jaeyeaon Cho

Theses

Sleep deprivation (SD) has been thought a potential factor to trigger cardiovascular events by increasing the sympathetic nervous system activity. The aim of the present study was to evaluate the relationship between sleep deprivation and the autonomic nervous system activity by means of heart rate variability (HRV) and blood pressure variability (BPV). All data were acquired in the sleep lab of Columbia University.

Data were acquired from the two groups, SD and control. Subjects in the SD group did not sleep for thirty-six hours but subjects in the control group slept at night as usual. There were five different data …

An In Vitro Evaluation Of Tyrosine Derived Polyarylates And Polycarbonate As Polymeric Scaffold For Human Mesenchymal Stem Cells Osteogenic Differentiation, Manish Suresh Godbole

Theses

Human mesenchymal stem cells (hMSCs) obtained from the adult bone marrow are multipotential cells that are capable of differentiating along several lineages. They are readily available and abundant source of cells in the field of tissue engineering. For their use in treating certain connective tissue defect or disorders, their success depends at minimum on the use of scaffolds that support differentiation. Therefore , this thesis details a study that systematically evaluated hMSC differentiation on materials that exhibit gradual range in surface properties as a first study for selecting materials as potential scaffolds. Polycarbonates and polyarylates have combinatorial libraries that exhibit …

Characterization Of Electrospun Dlplga Nanofibers For A Drug Delivery System For Intracranial Tumors And Avms, Kimberly A. Griswold

Theses

Electrospinning processes apply electric fields to a polymer solution in order to produce strands of polymer in the nanoscale range. These polymer fibers are manipulated for their porosity, high surface area, fineness and uniformity. In order to create the ideal drug delivery system for intracranial arteriovenous malformations (AVMs) and tumors, D, L poly-(lactice-poly-glycolide) (DLPLGA) nanofibers were electrospun in a tetrahydrofuran (THF) solvent. Three different concentration ratios of DLPLGA, 85/15, 80/20, and 75/25 were analyzed to obtain the prime base for drug annexation. 1 ,3-bis (2-chloroethyl)- 1 -nitrosourea (BCNU) was then codissolved with the DLPLGA nanofibers to form a homogenous solution, …

Study Of Design Tradeoffs Of Dram And Sram Memories, Using Hspice Computer Simulation, Bageshri Kale

Theses

Semiconductor random access memories are complex systems that can be described by performance parameters such as memory cycle time, access delays, storage capacity, bit packing density, chip area and retention time. In this thesis, tradeoffs between cycle time, chip area, and storage size as reflected by bit line capacitance (Cbl) were studied as a function of particular design variables: memory cell capacitance (Cc); CMOS flip-flop sense amplifier (SA) transistor sizes; and size of precharge (PC), and word line (WL) switches. Performance was optimized using circuit simulation software, HSPICE, to observe DRAM and SRAM waveforms. With TSMC 0.18 micron technology, minimum …