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Articles 1381 - 1410 of 4264

Full-Text Articles in Engineering

Internet Traffic Over Wide Area Network - Statistical Modeling And Analysis, Yan Yi Lee Aug 2003

Internet Traffic Over Wide Area Network - Statistical Modeling And Analysis, Yan Yi Lee

Theses

This thesis provides results on trace data collecting and modeling of the Internet traffic over a Wide Area Network. The study is based on extensive data, gathered by tracing the actual packet exchange at the interfaces of devices on the WAN of BCCLS (Bergen County Cooperative Library System). A powerful network monitoring system WhatsUp Gold was employed to monitor the WAN, and logged the byte rates and packet rates sent and received at the interfaces. Different statistical distributions were employed to model the data traces. In comparison with some other statistical models - normal, lognormal, Weibull, and Pareto, which are …


Deposition And Characterization Of Laser-Ablated Silicon, Wenwen Luo Aug 2003

Deposition And Characterization Of Laser-Ablated Silicon, Wenwen Luo

Theses

Laser ablation is a powerful thin film deposition and material processing technology. In the Nonlinear Nanostructure Lab at NJIT, silicon films deposited by laser ablation have been studied for the potential applications in nonlinear optoelectronic devices. The previous studies have suggested that the deposited silicon has a hexagonal symmetry, being a polymorph of silicon that previously has been obtained only at very high pressure. This thesis is part of the continuous study and characterization of this new structure. The objective of the research was to gain better understanding of the hexagonal silicon properties as well as the mechanism that lead …


Service Differentiation In Multihop Wireless Packet Networks, Ilker Onat Aug 2003

Service Differentiation In Multihop Wireless Packet Networks, Ilker Onat

Theses

This work explores the potential of link layer scheduling combined with MAC layer prioritization for providing service differentiation in multihop wireless packet networks. As a result of limited power, multihop characteristic and mobility, packet loss ratio in wireless ad hoc networks tends to be high compared to wireline and one-hop mobile data networks. Therefore, for wireless ad hoc networks, DiffServ-like distributed service differentiation schemes are more viable than hard QoS solutions, which are mainly designed for wireline networks. The choice and implementation of proper queuing and scheduling methods, which determine how packets will use the channel when bandwidth becomes available, …


A Biologically Inspired Joint Model Using Engineering Methods To Enhance Understanding Of Muscle Activity, Richard Paradiso Aug 2003

A Biologically Inspired Joint Model Using Engineering Methods To Enhance Understanding Of Muscle Activity, Richard Paradiso

Theses

Compliant actuators and control methods have been known to exhibit similarities in human musculoskeletal systems. In order to better understand and improve the effects of force optimization under closed- loop conditions, a physical joint model was constructed with an agonist and an antagonist muscle operating under linear control. Utilizing LabVIEW software, compliant McKibben air muscles and Merlin stretch sensors, the author was able to incorporate a Bang-Bang controller and propose the inclusion of pulse width modulation (PWM) as well as a Proportional-Integral-Derivative (PD) controller to study the reflex loops under various levels of feedback sensitivity. The feedback mechanism, similar to …


Photonic Crystals Composed Of Thick Inductive And Capacitive Meshes, Jay Shah Aug 2003

Photonic Crystals Composed Of Thick Inductive And Capacitive Meshes, Jay Shah

Theses

The transmission properties of metal meshes are studied for single meshes, photonic double layers and photonic crystals. Simulations are performed with the Flomerics Micro-Stripes program for light of infrared and millimeter wavelengths. The Micro-Stripes program solves Maxwell's equations numerically and, for simulations of the transmittance of metal meshes, has been proven as good as an experiment. Input data are the geometrical parameters, the indices of refraction and the conductivity, chosen according to the Drude model. The light is assumed to be at normal incidence and the simulation results are compared with experiments.

Single layers of inductive meshes are studied for …


Co-Operative Location Updates For Mobile Nodes For Cellular Networks, Samir Shah Aug 2003

Co-Operative Location Updates For Mobile Nodes For Cellular Networks, Samir Shah

Theses

In current pure cellular networks, each and every mobile node updates it's location to the particular base station separately following certain algorithms, say timer based, mobility based or both. For the next generation wireless networks, which we can consider as a highly dense network, such location update algorithms prove to be very costly in the terms of overall location update traffic to the base station and average battery usage by each mobile node for location updates due to large number of mobile nodes for particular base station area.

Instead of using such one-to-one link for location updates, this report describes …


Production Of Nanocrystalline Nitramine Energetic Materials By Rapid Expansion Of Supercritical Solutions, Victor Stepanov Aug 2003

Production Of Nanocrystalline Nitramine Energetic Materials By Rapid Expansion Of Supercritical Solutions, Victor Stepanov

Theses

Nanotechnology is a rapidly evolving field and has been characterized as "the next industrial revolution". Nanostructured materials are receiving increasing amount of attention in fields ranging from electronics to metallurgy due to their novel and unique properties. This work was focused on exploring the benefits of nanofabrication of high density energetic materials. The work primarily focused on the feasibility and viability of recrystallization of nitramine explosives down to the nanometer crystal size (<100 nm). It is anticipated that properties of the high density energetic materials such as sensitivity, packing density, crystal quality, energetic performance will be benefited.

Rapid Expansion of Supercritical Solutions was chosen as the process most appropriate to realize the objective. Solubility of CL-20 in supercritical solutions was studied. Nitramine crystals with …


Low Interference Routing For Wireless Ad-Hoc Networks, Mohit Gupta Aug 2003

Low Interference Routing For Wireless Ad-Hoc Networks, Mohit Gupta

Theses

In this thesis the primary focus is on the problem of interference between messages. The thesis discusses why the messages are blocked in a system? How adding a message impacts the cost of all other available links, which can be established in the system.

This thesis analyzes how the availability of channels, increase in number of nodes and increase in the transmission range help in increasing the number of messages that can be handled in the network. It is also analyzes how critical is the selection of the maximum transmission range MTR, transmission range TR and required transmission range RTR. …


A Combined Channel-Modified Adaptive Array Mmse Canceller And Viterbi Equalizer, Richard M. Friedman Aug 2003

A Combined Channel-Modified Adaptive Array Mmse Canceller And Viterbi Equalizer, Richard M. Friedman

Theses

In this thesis, a very simple scheme is proposed which couples a maximum-likelihood sequence estimator (MLSE) with a X-element canceller. The method makes use of the MLSE's channel estimator to modify the locally generated training sequence used to calculate the antenna array weights. This method will increase the array's degree of freedom for interference cancellation by allowing the dispersive, desired signal to pass through the array undisturbed. Temporal equalization of the desired signal is then accomplished using maximum-likelihood sequence estimation. The T-spaced channel estimator coefficients and the array weights are obtained simultaneously using the minimum mean square error criteria. The …


Elastic Brain Image Registration Using Mutual Information, Srisheela Devabhaktuni Aug 2003

Elastic Brain Image Registration Using Mutual Information, Srisheela Devabhaktuni

Theses

Image Registration is the determination of a geometrical transformation that aligns points in one image of an object with corresponding points in another image. The source image is geometrically transformed to match the target image. The geometric transformation can be rigid or non-rigid. Rigid transformations preserve straight lines and angles between straight lines. The basic rigid transformations are rotation, scaling and translation.

In this thesis non-rigid registration using B-splines is the method being used to take into account the elastic change in the brain structure. The B-spline equation is a type of curved transformation that does not preserve the straightness …


Tree Based Reliable Topology For Distributing Link State Information, Ram Narayan Krishnan Aug 2003

Tree Based Reliable Topology For Distributing Link State Information, Ram Narayan Krishnan

Theses

Finding paths that satisfy the performance requirements of applications according to link state information in a network is known as the Quality-of- Service (QoS) routing problem and has been extensively studied. However, distributing link state information may introduce a significant protocol overhead on network resources. In this thesis, the issue on how to update link state information efficiently and effectively is investigated. A theoretical framework is presented, and a high performance link state policy that is capable of minimizing the false blocking probability of connections under a given update rate constraint is proposed. Through theoretical analysis, it is shown that …


Study Of Mosfet Degradation Under Substrate Injection And Hot Carrier Degradation, Bhawar S. Patel Aug 2003

Study Of Mosfet Degradation Under Substrate Injection And Hot Carrier Degradation, Bhawar S. Patel

Theses

With continued scaling of MOSFET's, the reliability of thin gate oxides is becoming increasingly important. Degradation issues due to fabrication technology may result in misinterpretation unless the actual physical situation arising at source, drain, gate and substrate of a transistor during processing is understood. This degradation is prominent in plasma processing due to wafer charging which occurs due to the reactive ions in the plasma. The voltages developed at source and drain junctions, depending upon polarity relative to the substrate cause the source and drain junctions to be forward biased or reverse biased. Keeping in view this type of physical …


Efficient Resource Allocation And Call Admission Control In High Capacity Wireless Networks, Jiongkuan Hou May 2003

Efficient Resource Allocation And Call Admission Control In High Capacity Wireless Networks, Jiongkuan Hou

Dissertations

Resource Allocation (RA) and Call Admission Control (CAC) in wireless networks are processes that control the allocation of the limited radio resources to mobile stations (MS) in order to maximize the utilization efficiency of radio resources and guarantee the Quality of Service (QoS) requirements of mobile users. In this dissertation, several distributed, adaptive and efficient RA/CAC schemes are proposed and analyzed, in order to improve the system utilization while maintaining the required QoS.

Since the most salient feature of the mobile wireless network is that users are moving, a Mobility Based Channel Reservation (MBCR) scheme is proposed which takes the …


Effects Of Implementation Of Decaborane Ions In Silicon, Cheng Li May 2003

Effects Of Implementation Of Decaborane Ions In Silicon, Cheng Li

Dissertations

The next generations of Si microelectronic devices will require ultra shallow p-type junctions formed by implantation of B ions with energies below 1 keV, at which available beam currents are severely limited by space charge effects. To solve this problem, decaborane (B10H14) cluster ion implantation has been suggested as an attractive alternative to conventional B implants, because one decaborane ion implants ten B atoms simultaneously and each of the B atoms only carries approximately 1/11 of the total ion energy. Thus the same implantation depth and dose as with monomer B ions can be obtained using …


New Full Wave Theory For Plane Wave Scattering By A Rough Dielectric Surface - The Fictitious Current Method, Byung-Tae Yoon May 2003

New Full Wave Theory For Plane Wave Scattering By A Rough Dielectric Surface - The Fictitious Current Method, Byung-Tae Yoon

Dissertations

A new full wave method for scattering of plane waves from a rough dielectric surface is developed. This new theory begins by postulating a zero-order field solution which does not satisfy Maxwell's source-free field equations. The zero-order field, however, is made to satisfy Maxwell's source equations. This is done by introducing a fictitious volume current distribution. Since the original problem does not possess a volume current distribution, its introduction represents a measure of the error in the postulated zero-order solution. To improve this solution, the fictitious volume current distribution is cancelled by the introduction of a second fictitious current distribution, …


Dynamic Multi-Ramp Metering Control With Simultaneous Perturbation Stochastic Approximation (Spsa), Jiangtao Luo May 2003

Dynamic Multi-Ramp Metering Control With Simultaneous Perturbation Stochastic Approximation (Spsa), Jiangtao Luo

Dissertations

Ramp metering was proven to be a viable form of freeway traffic control strategy, which could eliminate, or at least reduce, freeway congestion. In this study, the development of ramp metering control strategies, models, and constraints (e.g., meter locations, ramp storage capacities, lower and upper bounds of ramp metering rates) are discussed in detail. The pre-timed and demand/capacity metering control strategies were first evaluated, while the potential metered ramps were determined. A Simultaneous Perturbation Stochastic Approximation (SPSA) algorithm is proposed to dynamically optimize multiple-ramp metering control by maximizing the total throughput subject to a number of constraints. The ramp metering …


Theoretical And Experimental Studies Of The Field-Induced Phenomena In Flowing Suspensions, Nikolai Markarian May 2003

Theoretical And Experimental Studies Of The Field-Induced Phenomena In Flowing Suspensions, Nikolai Markarian

Dissertations

The present work describes results of experimental and theoretical studies of the behavior of dilute suspensions subject to high gradient AC electric fields. When a spatially non-uniform electric field is applied to a suspension, in which the particles and the suspending fluid have different dielectric permittivities andlor conductivities, the particles migrate towards the regions of high or low electric field strengths depending on the sign of their polarization. This phenomenon, referred to as dielectrophoresis, has found numerous applications for the control and manipulation of the particle motions.

Presented in Chapter 3 are the results of studying the field -induced motion …


Development Of A Multivariate Logistic Model To Predict Bicycle Route Safety In Urban Areas, Cheryl Allen-Munley May 2003

Development Of A Multivariate Logistic Model To Predict Bicycle Route Safety In Urban Areas, Cheryl Allen-Munley

Dissertations

In response to the renewed appreciation of the benefits of bicycling to the environment and public health, public officials across the nation are working to establish new bicycle routes. During the past two decades, a number of methods have been endorsed for the selection of "suitable" bicycle routes. These methods are limited in that they do not explicitly address bicycle safety nor do they reflect urban conditions.

The purpose of this research is to develop an objective bicycle route safety rating model based on injury severity. The model development was conducted using a logistic transformation of Jersey City's bicycle crash …


Investigation Of An Integrated Regional Environmental Watershed Methodology, Marshall R. Boggio May 2003

Investigation Of An Integrated Regional Environmental Watershed Methodology, Marshall R. Boggio

Dissertations

Recent public awareness of the environment has placed increased emphasis on the health and current state of the regional watershed. The watershed has been defined as that area in which water flowing across and beneath a given land surface drains into a specific stream or river, ultimately flowing through a single point or outlet on that stream or river. Since the processes involved are many and are analyzed in the literature on an individual basis, the current investigation attempts a more holistic approach by suggesting a methodology that integrates all elements of the hydrologic cycle. The investigation utilizes the area …


Time-Frequency Investigation Of Heart Rate Variability And Cardiovascular System Modeling Of Normal And Chronic Obstructive Pulmonary Disease (Copd) Subjects, Douglas Alan Newandee May 2003

Time-Frequency Investigation Of Heart Rate Variability And Cardiovascular System Modeling Of Normal And Chronic Obstructive Pulmonary Disease (Copd) Subjects, Douglas Alan Newandee

Dissertations

A study has been designed to add insight to some questions that have not been fully investigated in the heart rate variability field and the cardiovascular regulation system in normal and Chronic Obstructive Pulmonary Disease (COPD) subjects. It explores the correlations between heart rate variability and cardiovascular regulation, which interact through complex multiple feedback and control loops. This work examines the coupling between heart rate (HR), respiration (RESP), and blood pressure (BP) via closed-loop system identification techniques in order to noninvasively assess the underlying physiology.

In the first part of the study, the applications of five different bilinear time-frequency representations …


Spatio-Temporal Correlation Models For Indoor Mimo Channels, Kaustubha Raghukumar May 2003

Spatio-Temporal Correlation Models For Indoor Mimo Channels, Kaustubha Raghukumar

Theses

Accurate modeling of the spatio-temporal cross-correlation between the subchannels of a multiple-input multiple-output (MIMO) channel is an important prerequisite of multi-element antenna system design. In this thesis, a new model for indoor MIMO channels is proposed, and a closed form expression for the spatio-temporal cross-correlation function is derived. This new analytical correlation expression includes many physical parameters of interest such as the angle-of-arrivals at the base station and the user, the associated angle spreads, and other parameters, in a compact form. Comparison of this model with narrowband indoor MIMO data collected at Brigham Young University exhibits the utility of the …


Experimental Study Of Ignition Of Mechanical Alloy And Pure Metal Powders, Ruslan Mudryy May 2003

Experimental Study Of Ignition Of Mechanical Alloy And Pure Metal Powders, Ruslan Mudryy

Theses

Mechanical alloys of Al Mg, AI Zr, Al Ti, Al Li, Al C, Al Mg H, B Mg, B Al, and B Ti were produced and tested for possible applications as high energy density additives to fuels, propellants, explosives, and incendiaries. These new materials are metastable, supersaturated, nanocrystalline solid solutions that include a base metal as a solvent and another component (metal or gas, e.g. hydrogen) as a solute. Phase changes occurring in such materials during ignition and combustion are expected to significantly affect both ignition and bum rates. This experimental program focused on the characterization of ignition kinetics of …


The Consolidation Analysis Of A Clay Layer In The City Of Belem Do Para, Brazil, John Bezerra Jr. May 2003

The Consolidation Analysis Of A Clay Layer In The City Of Belem Do Para, Brazil, John Bezerra Jr.

Theses

In this study, an analysis was done on a particular clay layer found in the city of Belem do Para, Brazil. Various soil tests were conducted including a consolidation analysis. Data were gathered and analyzed in order to obtain a better understanding of how the soil responds under certain loading conditions. There have been no previous studies done on this material and so when it has been encountered in the field geotechnical engineers provide the safest, but not necessarily best design method possible. In the case of large buildings, piles are driven past this material to competent sand. There have …


Shape Finding Of Fabric Structures Using Grid Method, Armin Bischof May 2003

Shape Finding Of Fabric Structures Using Grid Method, Armin Bischof

Theses

Fabric structures can span large distances with a very low self-weight, which makes them very efficient for covering huge areas. They have attractive shapes and an appealing architecture. These properties make them very popular and they are used in many different kinds of buildings. Airports, stadiums and halls are typical examples where the use fabric structures is often recommendable.

Fabric structures are built mainly out of fabric and cables; two structural members that can only take tension stresses. Therefore these structural members must be prestressed in such a way that their shape can carry all loads that might affect the …


Improving The Process Of Laser Retinal Eye Surgery Using Electro Static Micro Mirrors, Narashiman Chakravarthy May 2003

Improving The Process Of Laser Retinal Eye Surgery Using Electro Static Micro Mirrors, Narashiman Chakravarthy

Theses

This thesis describes an improved system for laser eye surgery. The system incorporates hardware based image matching and MEMS micromirrors for feedback control of laser positioning on the eye. Many benefits are described in this thesis, such as nulling out eye movement, tracking laser firing history, enabling precise control of laser firing locations and preventing firing accidents. The aim of this work is to frame this improved laser surgery concept and prove the principle of various components of the system. A featured accomplishment is the modeling and simulation of a prototype microcontroller using VHDL that may be incorporated as part …


Labview-Controlled Stimulus Presentation On A Monitor For Smooth Pursuit Eye Movement Experiments, Florence Bautista Chua May 2003

Labview-Controlled Stimulus Presentation On A Monitor For Smooth Pursuit Eye Movement Experiments, Florence Bautista Chua

Theses

Smooth pursuit is an example of how movements in the visual world guide involuntary oculomotor movements. A current system to study eye movements uses an oscilloscope screen. A computer screen offers many advantages: a greater visual field, the use of shapes, 32 bits of colors, and increased timing accuracy. To control stimulus display on a computer monitor, instrumentation was developed in LabVIEW. Initial studies supported a draw/redraw to erase method for stimulus presentation. An experiment compared the computer monitor to the oscilloscope. Indeed, the monitor display was an improvement over the oscilloscope for vision research.


Hop-Limited Routing For Multihop Cellular Networks, Cem Dincer May 2003

Hop-Limited Routing For Multihop Cellular Networks, Cem Dincer

Theses

In recent years, conventional cellular systems have experienced evolution in fields of data oriented services. During this period, the requirement for high data-rate stimulated new research proposals, which resulted in a new architecture: Multihop Cellular Networks (MCN), where multihop structure enables mobile stations to forward packets from other mobile stations to the base station on the uplink, and in turn, forward packets to other mobile stations from the base station on the downlink. In this thesis, a new routing algorithm is introduced for MCNs in order to limit the number of hops between the base station and the mobile stations …


Characterization And Mapping Of Crystal Defects In Silicon Carbide, Ejiro Emorhokpor May 2003

Characterization And Mapping Of Crystal Defects In Silicon Carbide, Ejiro Emorhokpor

Theses

Silicon carbide (SiC) is a semiconductor with attractive properties, such as a wide bandgap (3. 26 eV), high dielectric strength, and high thermal conductivity that make it suitable for high power, highspeed electronic devices. A major roadblock to its wider application is the presence of defects, particularly micropipes and dislocations, in SiC wafers produced today and decreasing density of these defects is the most important challenge of the industry. The goal of this thesis was to design, build and test a system for detection and analysis of the defects in SiC wafers. The system is based on the reflection optical …


Role Of Catalyst And Substrate In Synthesis Of Single Wall Carbon Nanotubes, Amit Goyal May 2003

Role Of Catalyst And Substrate In Synthesis Of Single Wall Carbon Nanotubes, Amit Goyal

Theses

The synthesis of single wall carbon nanotubes (SWNTs) by the catalyticdisproportionation of carbon monoxide (CO) (i.e., Boudouard reaction) at I atm pressureand 700-800 C, has been systematically investigated in order to determine whether theprocess can be used for the large scale production. SWNT diameter distribution andmorphology were studied by Raman scattering, and scanning and transmission electronmicroscopy, respectively. X-ray diffraction was used to determine levels of the remnantcatalyst and support. Synthesis experiments were conducted using a three-stage processwith hydrogen to reduce the catalyst-precursor and argon to cool the system. Two typesof catalyst/support synthesis were studied: (1) Combustion synthesis to form catalyst …


Fpga Implementation Of A Cholesky Algorithm For A Shared-Memory Multiprocessor Architecture, Satchidanand G. Haridas May 2003

Fpga Implementation Of A Cholesky Algorithm For A Shared-Memory Multiprocessor Architecture, Satchidanand G. Haridas

Theses

Solving a system of linear equations is a key problem in the field of engineering and science. Matrix factorization is a key component of many methods used to solve such equations. However, the factorization process is very time consuming, so these problems have traditionally been targeted for parallel machines rather than sequential ones. Nevertheless, commercially available supercomputers are expensive and only large institutions have the resources to purchase them or use them. Hence, efforts are on to develop more affordable alternatives. This thesis presents one such approach.

The work presented here is an implementation of a parallel version of the …