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2011

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Articles 1 - 30 of 6828

Full-Text Articles in Engineering

Identification And Thermochemical Analysis Of High-Lignin Feedstocks For Biofuel And Biochemical Production, Venugopal Mendu, Anne Harman-Ware, Mark Crocker, Jungho Jae, Jozsef Stork, Samuel Morton, Andrew Placido, George Huber, Seth Debolt Dec 2015

Identification And Thermochemical Analysis Of High-Lignin Feedstocks For Biofuel And Biochemical Production, Venugopal Mendu, Anne Harman-Ware, Mark Crocker, Jungho Jae, Jozsef Stork, Samuel Morton, Andrew Placido, George Huber, Seth Debolt

Samuel A Morton

Background - Lignin is a highly abundant biopolymer synthesized by plants as a complex component of plant secondary cell walls. Efforts to utilize lignin-based bioproducts are needed. Results - Herein we identify and characterize the composition and pyrolytic deconstruction characteristics of high-lignin feedstocks. Feedstocks displaying the highest levels of lignin were identified as drupe endocarp biomass arising as agricultural waste from horticultural crops. By performing pyrolysis coupled to gas chromatography-mass spectrometry, we characterized lignin-derived deconstruction products from endocarp biomass and compared these with switchgrass. By comparing individual pyrolytic products, we document higher amounts of acetic acid, 1-hydroxy-2-propanone, acetone and furfural in switchgrass ...


An Optimal-Model Of Entry, Ticketing And Seating Of Neyland Stadium, Isaac Atuahene, Rupy Sawhney, Xueping Li, Charles Aikens Oct 2013

An Optimal-Model Of Entry, Ticketing And Seating Of Neyland Stadium, Isaac Atuahene, Rupy Sawhney, Xueping Li, Charles Aikens

Isaac Atuahene

No abstract provided.


Simulated Annealing Technique To Design Minimum Cost Exchanger, Nadeem Muhammed Khalfe, Sandip K. Lahiri, Shiv K. Wadhwa Dec 2011

Simulated Annealing Technique To Design Minimum Cost Exchanger, Nadeem Muhammed Khalfe, Sandip K. Lahiri, Shiv K. Wadhwa

Nadeem Khalfe

Owing to the wide utilization of heat exchangers in industrial processes, their cost minimization is an important target for both designers and users. Traditional design approaches are based on iterative procedures which gradually change the design and geometric parameters to satisfy a given heat duty and constraints. Although well proven, this kind of approach is time consuming and may not lead to cost effective design as no cost criteria are explicitly accounted for. The present study explores the use of non-traditional optimization technique called simulated annealing (SA), for design optimization of shell and tube heat exchangers from an economic point ...


Wireless Sensor Network For Health Monitoring, Jin Soo Choi Dec 2011

Wireless Sensor Network For Health Monitoring, Jin Soo Choi

Dissertations

Wireless Sensor Network (WSN) is becoming a significant enabling technology for a wide variety of applications. Recent advances in WSN have facilitated the realization of pervasive health monitoring for both homecare and hospital environments. Current technological advances in sensors, power-efficient integrated circuits, and wireless communication have allowed the development of miniature, lightweight, low-cost, and smart physiological sensor nodes. These nodes are capable of sensing, processing, and communicating one or more vital signs. Furthermore, they can be used in wireless personal area networks (WPANs) or wireless body sensor networks (WBSNs) for health monitoring. Many studies were performed and/or are under ...


Cerebral Spasticity Modeled As Disorded Equilibrium Point Control, Darnell Simon Dec 2011

Cerebral Spasticity Modeled As Disorded Equilibrium Point Control, Darnell Simon

Dissertations

Spasticity is a highly complex phenomenon, which has not been defined in precise and quantifiable terms. Although the muscle stretch reflex is thought to play an important role in spasticity generation, the pathophysiologic basis of spasticity is not completely understood. A valid measure of spasticity is one that is chosen within the context of a theory describing the physiological mechanisms underlying the control of posture and movement in healthy individuals and possible impairments of these mechanisms leading to motor disorders. This research’s goal was to determine the role of stretch reflex threshold in the regulation of impaired motor control ...


Source Localization Via Time Difference Of Arrival, Ciprian Romeo Comsa Dec 2011

Source Localization Via Time Difference Of Arrival, Ciprian Romeo Comsa

Dissertations

Accurate localization of a signal source, based on the signals collected by a number of receiving sensors deployed in the source surrounding area is a problem of interest in various fields. This dissertation aims at exploring different techniques to improve the localization accuracy of non-cooperative sources, i.e., sources for which the specific transmitted symbols and the time of the transmitted signal are unknown to the receiving sensors. With the localization of non-cooperative sources, time difference of arrival (TDOA) of the signals received at pairs of sensors is typically employed.

A two-stage localization method in multipath environments is proposed. During ...


Distributed Spectrum Leasing Via Cooperation, Tariq Elkourdi Dec 2011

Distributed Spectrum Leasing Via Cooperation, Tariq Elkourdi

Dissertations

“Cognitive radio” networks enable the coexistence of primary (licensed) and secondary (unlicensed) terminals. Conventional frameworks, namely commons and property-rights models, while being promising in certain aspects, appear to have significant drawbacks for implementation of large-scale distributed cognitive radio networks, due to the technological and theoretical limits on the ability of secondary activity to perform effective spectrum sensing and on the stringent constraints on protocols and architectures.

To address the problems highlighted above, the framework of distributed spectrum leasing via cross-layer cooperation (DiSC) has been recently proposed as a basic mechanism to guide the design of decentralized cognitive radio networks. According ...


Trust Management Schemes For Peer-To-Peer Networks, Lin Cai Dec 2011

Trust Management Schemes For Peer-To-Peer Networks, Lin Cai

Dissertations

Peer-to-peer (P2P) networking enables users with similar interests to exchange, or obtain files. This network model has been proven popular to exchange music, pictures, or software applications. These files are saved, and most likely executed, at the downloading host. At the expense of this mechanism, worms, viruses, and malware find an open front door to the downloading host and gives them a convenient environment for successful proliferation throughout the network. Although virus detection software is currently available, this countermeasure works in a reactive fashion, and in most times, in an isolated manner. A trust management scheme is considered to contain ...


Influence Of Defects And Impurities On Solar Cell Performance, Vinay Budhraja Dec 2011

Influence Of Defects And Impurities On Solar Cell Performance, Vinay Budhraja

Dissertations

Multicrystalline silicon (mc-Si) solar cells exhibit high impurity content and higher density of crystal defects such as grain boundaries, dislocations, stacking faults and impurity precipitates. Even though the effect of dislocations on mc-Si solar cell performance has been studied, a severe lack of understanding of the quantitative effects of dislocations on cell parameters still exists. Some correlation has been reported under the assumption of a uniform distribution of dislocation density and a negligible effect of front and back surface recombination velocity. This assumption can cause a significant error as the current mc-Si technology provides good surface passivation by SiN:H ...


High Rate Space Time Code With Linear Decoding Complexity For Multiple Transmitting Antennas, Amir Laufer Dec 2011

High Rate Space Time Code With Linear Decoding Complexity For Multiple Transmitting Antennas, Amir Laufer

Dissertations

The multipath nature of the wireless channel, results in a superposition of the signals of each path at the receiver. This can lead to either constructive or destructive interference. Strong destructive interference is frequently referred to as deep fade and may result in temporary failure of communication due to the severe drop in the channel's signal-to-noise ratio (SNR). To avoid this situation, signal diversity might be introduced. When having more than one antenna at the transmitter and / or receiver, forming a Multiple-Input Multiple-Output (MIMO) channel, spatial diversity can be employed to overcome the fading problem. Space time block codes ...


Neuralsta: A Software Tool For Neural Stimulation And Recording Applications With A Laser Control, Rimi Sahu Dec 2011

Neuralsta: A Software Tool For Neural Stimulation And Recording Applications With A Laser Control, Rimi Sahu

Theses

The subject of this thesis is a software tool created in Matlab ® for neural stimulation and recording of the evoked potentials. The stimulation output can be delivered in electrical units for immediate use for neural stimulation or as a power control signal to a laser. NeuralSTA is designed to generate arbitrary waveforms of stimulation and simultaneously record the neural response while implementing the spike triggered averaging (STA) method, hence the name NeuralSTA. The output (stimulation) signal can be created in monophasic, biphasic or inverted monophasic forms (for laser control applications). Controls for pulse modulation allow shaping of the pulse waveform ...


Combustion Dynamics Of Individual Reactive Material Particles, Carlo Francisco Badiola Dec 2011

Combustion Dynamics Of Individual Reactive Material Particles, Carlo Francisco Badiola

Theses

Metallic reactive powders are widely used as solid fuels, pyrotechnic materials, and components of enhanced blast explosives. Metals are attractive because of their high combustion enthalpies and temperatures. Quantitative descriptions of the combustion processes and mechanisms for both pure metal and composite particles are also desired for their proper implementation in specific applications. Among reactive metals, Al is used most widely and its combustion has been studied extensively. A recently developed experimental setup using laser-ignited metal powders enabled one to record optical signatures for time-resolved combustion instances for 2-25 µm diameter aluminum particles burning in different atmospheres. Individual particle diameters ...


Theoretical Prediction Of Joint Reaction Force In A Dynamic General 3-D Pendulum Tree Model For Human Or Animal Motion, Sucheta Goyal Dec 2011

Theoretical Prediction Of Joint Reaction Force In A Dynamic General 3-D Pendulum Tree Model For Human Or Animal Motion, Sucheta Goyal

Theses

Lagrangian dynamics and the method of superfluous coordinates are applied to predict dynamic joint reaction forces in an idealized flexible model of a branched 3-D pendulum tree system. The number of segments and joints on the tree are adjustable as is the branching tree pattern. The segments that comprise the tree are assumed to be one- dimensional rigid rods containing a discrete set of mass points that is both flexible in number and distribution on the tree. The idealized 3-D pendulum tree system is intended to provide a flexible theoretical framework to model and better understand the dynamics of human ...


Hydrogen Storage In Pt/Carbon Nanotube Sheets, An-Yu Ma Dec 2011

Hydrogen Storage In Pt/Carbon Nanotube Sheets, An-Yu Ma

Theses

Three types of self-assembled carbon nanotube (CNT) sheets, for example, carboxylic functionalized multi-walled CNTs (MWNTs-COOH), pure multi-walled CNTs (MWNTs), and pure single-walled CNTs (SWNTs), were prepared as substrates by ambient environment vacuum filtration of suspensions of the nanotubes. To enhance hydrogen storage on the CNTs, platinum particles were deposited on the three types of CNT sheets using two processes: electrodeposition (ED) using a DC power source and electrochemical deposition under cyclic voltammetry (CV). To verify platinum deposition on the surface of the CNT sheets, a Scanning Electron Microscope (SEM) was used to obtain images, and Energy Dispersive X-ray (EDX) spectroscopy ...


Alendronate Treatment Elicits A Reduction In Fatigue-Life Of Canine Cortical Bone, Joseph Ryan Geissler Dec 2011

Alendronate Treatment Elicits A Reduction In Fatigue-Life Of Canine Cortical Bone, Joseph Ryan Geissler

Theses

Bone serves contradictory needs; bone must be strong yet light, and stiff yet flexible. At the tissue level bone material withstands cyclic loading without failing by dissipating energy via the formation and accumulation of microdamage. Proper removal of this damage in exchange for fresh tissue is vital to bone maintenance, and is achieved through a remodeling process. Imbalanced remodeling leads to osteoporotic fractures. Bisphosphonate drugs are proven to reduce fracture risk. However, the long-term effects of bisphosphonates on tissue-level properties are unknown. This study characterized the fatigue-life of cortical bone tissue after bisphosphonate treatment with alendronate (Aln). 1 1th ribs ...


The Mechanical Testing Of Single Nanofiber, Pratik Manohar Dahule Dec 2011

The Mechanical Testing Of Single Nanofiber, Pratik Manohar Dahule

Theses

Polymer nanofibers exhibit properties that make them a favorable material for the development of tissue engineering scaffolds, filtration devices, sensors, and high strength lightweight materials. Perfectly aligned PLLA Nanofibers were fabricated by an electrospinning technique under optimum conditions and the diameter of the electrospun fibers can easily be tailored by adjusting the concentration of the polymer solution. To align the nanofibers, special arrangement was made in terms of two aluminum plates. Good alignment of polymer nanofibers on specimen was confirmed by SEM observation. The effect of different electro-spinning parameters on maximum fiber length, average fiber diameter, diameter uniformity, and fiber ...


Single-Carrier Frequency Domain Equalization Using Subband Decomposition For Optical Wireless Communications, Di Mu Dec 2011

Single-Carrier Frequency Domain Equalization Using Subband Decomposition For Optical Wireless Communications, Di Mu

Theses

Optical wireless communication is intended to be applied into indoor and visual distance high-rate data transmission, which is complementary to radio frequency communications. There are specific problems and requirements in optical wireless communications compared with radio frequency communications. Single-carrier frequency domain equalization (SCFDE) is a transmission scheme which has been considered as an alternative of orthogonal frequency-division multiplexing (OFDM), because it has most of the advantages of OFDM and avoids the problems of OFDM. Subband decomposition is a multi-resolution signal analysis and synthesis method, using quadrature mirror filter (QMF) bank to convert time-domain signal to frequency-domain subbands. As a time-to-frequency ...


Soy Protein-Poly (L-Lactic Acid) Blend Nanofibers For Drug Delivery Of Nardostachys Jatamansi, Swetha Tiwari Dec 2011

Soy Protein-Poly (L-Lactic Acid) Blend Nanofibers For Drug Delivery Of Nardostachys Jatamansi, Swetha Tiwari

Theses

Electrospun nanofibers when nanofi bers are impregnated with drugs play a significant role in drug delivery. Nanomedical approaches to drug delivery focus on developing nanoscale particles or molecules to improve the bioavailab ility of a drug.

Biodegradable nanofibers were developed using Poly (L – lactic acid) and Soy protein for the delivery of an ayurvedic drug, Nardostachys jatamansi. A weighed quantity of powdered drug – Nardostachys Jatamansi was subjected to Soxhlet extraction using water and ethanol in equal quantities. Various blends of the drug extract and soy protein solution are prepared and mixed in Poly (L-lactic acid). Nanofibers of Soy Protein – Poly ...


Development Of Gis Database For Hayward Fault, Olugbope Maku Dec 2011

Development Of Gis Database For Hayward Fault, Olugbope Maku

Theses

Earthquake activity and its attendant effects on the earth surface have been a major concern for some time now, especially considering their negative effects in loss of human life, property damage including the emotional impact on witnesses. This study focuses on the Hayward Fault, located in the heart of population center in Contra Costa County of the San Francisco Bay Area, California.

Geographical Information System (GIS) has proved to be a valuable tool in recent years in the study and analysis of earthquakes to complement emergency response efforts. GIS has been adapted to estimate the impact of the geologic hazards ...


Neural Differentiation Of Pluripotent Stem Cells And Applications To Micropatterned Agarose Hydrogel For Nerve Guidance, Jamila S. Gittens Dec 2011

Neural Differentiation Of Pluripotent Stem Cells And Applications To Micropatterned Agarose Hydrogel For Nerve Guidance, Jamila S. Gittens

Theses

Many central nervous system (CNS) disorders are attributable to damaged oligodendrocytes, the cells that form the myelin sheath of axons. An effective source of human oligodendrocytes is crucial, making pluripotent stem cells, such as embryonic stem (ES) cells, an attractive source for nerve tissue repair and regeneration due to their unlimited capacity for self-renewal and their ability to differentiate into all major cell lineages. Bioengineered 3-D hydrogel culture systems have the potential to elucidate mechanisms required for regeneration of CNS cells. The goals of this study are: (1) to investigate the effects of retinoic acid (RA), sonic hedgehog (shh) agonist ...


Development Of 3-D Liver Model For Drug Screening Applications, Divya Rajendran Dec 2011

Development Of 3-D Liver Model For Drug Screening Applications, Divya Rajendran

Theses

The need for a an in vitro drug screening system that mimics the structural organization of natural liver for multi-functionality and maintenance of hepatocytes has become vital in the drug development process. The objective of this study was to engineer a three-dimensional (3-D) liver model using chitosan-based nanofiber scaffolds and co-culture system (adult rat hepatocytes and 3T3-J2 fibroblasts) to mimic the natural liver and to justify its application for in vitro drug screening. Chitosan nanofiber scaffolds were fabricated by electrospinning technique. In order to promote cell adhesion on the chitosan scaffolds, the scaffolds were coated with a cell adhesion molecule ...


Temperature Elevations Due To Nir Exposure In The Brain Tissue, Ali Ersen Dec 2011

Temperature Elevations Due To Nir Exposure In The Brain Tissue, Ali Ersen

Theses

Near infrared (NIR) lasers have been used in medical applications both for diagnostic and therapeutic purposes. Temperature elevation profile inside the tissue is a critical factor that needs to be better understood in these applications. The purpose of this study is to determine the temperature distribution due to a low power N I R laser irradiation in living neural tissue. Temperature measurements were made directly using a thermocouple probe inside the rat brain cortex within the sagittal plane. The spatial map indicates that N I R light penetrates more readily in the vertical directions than the spreading in the horizontal ...


Analysis And Mitigation Of Carrier Frequency Offset For Uplink Of Ofdma, Abhishek R. Panchal Dec 2011

Analysis And Mitigation Of Carrier Frequency Offset For Uplink Of Ofdma, Abhishek R. Panchal

Theses

Orthogonal Frequency Division Multiplexing (OFDM) is being used in many wireless standards because of its immunity to multipath fading, high spectral efficiency and simple implementation, making it suitable for high data rate multimedia wireless applications. One of the significant drawbacks of the OFDM is its sensitivity to Carrier Frequency Offset (CFO). CFO causes Inter Carrier Interference (ICI) between subcarriers and Multiple User Interference (MUI) at Uplink between different users. ICI and MUI at uplink cause significant degradation in the performance of the receiver, therefore, to improve the receiver performance up to acceptable level, compensation of the CFO becomes necessary.

In ...


Dynamic Friction: Measurement And Results, Yanal Jij Dec 2011

Dynamic Friction: Measurement And Results, Yanal Jij

Theses

Friction has been known as a phenomenon since Leonardo da Vinci era. From that time and through the last four centuries, scientists tried to understand this phenomenon in an effort to overcome its undesired side effects which include energy loss, parts wearing, and errors in control systems. Much has been achieved in studying friction and many experiments have been conducted in this field. These experiments resulted in a mounting evidence that friction is a dynamic phenomenon.

This thesis presents an apparatus that measures dynamic friction in linear motion and the results obtained using this apparatus. The apparatus consists of a ...


Development Of X-Ray Holography Methods For Structure Determination : Application Of High Speed Detectors And Novel Numerical Methods, Yuhao Wang Dec 2011

Development Of X-Ray Holography Methods For Structure Determination : Application Of High Speed Detectors And Novel Numerical Methods, Yuhao Wang

Dissertations

Holographic methods show much promise to enable direct determination of atomic structure with minimal assumptions and approximations. The approach can, in principle, provide three dimensional information on atomic positions. However, significant developments in experimental techniques, instrumentation and in data collection and analysis are needed. A review of the holography method is given with a focus on X-ray fluorescence holography. Methods for analysis of X-ray holographic data are also reviewed. An overview of the detectors relevant to X-ray measurements is also presented. An experimental apparatus for rapid acquisition of X-ray holographs using novel X-ray detectors has been developed. The integration of ...


Target Localization In Passive And Active Systems : Performance Bonds, Vlad Mihai Chiriac Dec 2011

Target Localization In Passive And Active Systems : Performance Bonds, Vlad Mihai Chiriac

Dissertations

The main goal of this dissertation is to improve the understanding and to develop ways to predict the performance of localization techniques as a function of signal-to-noise ratio (SNR) and of system parameters. To this end, lower bounds on the maximum likelihood estimator (MLE) performance are studied. The Cramer-Rao lower bound (CRLB) for coherent passive localization of a near-field source is derived. It is shown through the Cramer-Rao bound that, the coherent localization systems can provide high accuracies in localization, to the order of carrier frequency of the observed signal. High accuracies come to a price of having a highly ...


Single And Multiphase Mixing In Partially Filled Stirred Vessels, Shilan Motamedvaziri Dec 2011

Single And Multiphase Mixing In Partially Filled Stirred Vessels, Shilan Motamedvaziri

Dissertations

In many industrial applications, mixing vessels have a liquid height-to-tank diameter ratio, H/T, equal to, or larger than 1. However, there are many instances where this ratio is lower than 1, as in all those cases in which the vessel is either emptied or filled. Even when H/T<1, sufficient agitation must still be provided in order to attain the desired process objectives. When the impeller submergence is reduced as a result of lowering the liquid level, the fluid dynamics of even a single-phase stirred liquid can become quite complex, with different regimes possibly existing depending on the geometric characteristics of the system (such as impeller clearance, liquid height, or liquid submergence above the impeller). The objectives of this work were to study in detail the hydrodynamic changes that occur when H/T is decreased, and to determine the minimum liquid levels and the critical impeller submergence for different impeller off-bottom distances, impeller diameters and agitation speeds where adequate mixing process can still be achieved, both in a single liquid phase and in solid-liquid suspensions.

Flat-bottomed, baffled vessels (5L, 12L, 20L and 170L) equipped with a single disk turbine (DT) of four different sizes placed at five different impeller off-bottom clearances were used here to study the system's hydrodynamics and related mixing phenomena. A number of experimental tools were used to analyze the systems ...


Micromechanical Study Of Two-Phase Flow During Air Sparging, Shengyan Gao Dec 2011

Micromechanical Study Of Two-Phase Flow During Air Sparging, Shengyan Gao

Dissertations

Air sparging (AS) is an in-situ soil/groundwater remediation technology, which involves the injection of pressurized air/oxygen through an air sparging well below the region of contamination. The efficiency of the in-situ sparging system is mainly controlled by the extent of contact between injected air and contaminated soil and pore fluid. Hence, characterizing the mechanisms governing movement of air through saturated porous media is therefore critical to the design of an effective cleanup treatment. However, in spite of the success of air sparging as a remediation technique for the clean-up of contaminated soils, to date, the fundamental mechanisms or ...


Analysis Of A Composite Dielectric-Ferrite Loaded Resonator Using The Transmission Line Model With Application To A Tunable Dual Mode Bandpass Filter, Charlotte Blair Dec 2011

Analysis Of A Composite Dielectric-Ferrite Loaded Resonator Using The Transmission Line Model With Application To A Tunable Dual Mode Bandpass Filter, Charlotte Blair

Dissertations

A magnetically tuned filter is presented in this dissertation. Filter tuning of a dielectric ceramic resonator is accomplished using by using two oppositely biased ferrites. Specifically, a change in the applied magnetic field is used to alter the permeability of the ferrite so as to achieve maximum tuning range. Through electromagnetic (EM) simulations and laboratory experiments, tuning of the filter passband by 20 MHz is demonstrated.

This investigation focuses on the design of a bandpass resonator using a combination of dielectric-ferrite material layers. An initial simplification of the geometry of the structure is used as the basis for a program ...


Hot-Melt Mixing Of Partially Miscible Active Pharmaceutical Ingredient-Polymer Mixtures, Min Yang Dec 2011

Hot-Melt Mixing Of Partially Miscible Active Pharmaceutical Ingredient-Polymer Mixtures, Min Yang

Dissertations

Solid dispersion/solution processes for producing pharmaceutical oral dosages such as hot-met extrusion (HME) have received increasing attention by industry and academe because they can enhance drugs’ solubility and even bioavailability to a great extent by converting drugs from crystalline to amorphous form. HME can be carried out at two process temperature regimes: one where Tprocess > Tm of the drug and the Tg of the polymer (or the Tm for the case of semi-crystalline polymers); the other at Tm > Tprocess > Tg (Tm for the case of semi-crystalline polymer). Processing below the drug ...