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Articles 2611 - 2640 of 3180

Full-Text Articles in Engineering

Functional Near Infrared Spectroscopy For The Assessment Of Motor Cortex Plasticity In Pediatric Subjects Affected By Cerebral Palsy, Bilal Khan Jan 2009

Functional Near Infrared Spectroscopy For The Assessment Of Motor Cortex Plasticity In Pediatric Subjects Affected By Cerebral Palsy, Bilal Khan

Bioengineering Theses - Archive

Functional near infrared spectroscopy (fNIRS) is widely used to monitor hemodynamic changes occurring in the cerebral cortex as a result of neuronal activation. One of the current challenges in this field is that activation-related hemodynamic signals are often eclipsed by global hemodynamic fluctuations due to cardiac pulsation, respiration and Mayer waves. In this study, we demonstrate by using a combination of principal component analysis (PCA) and adaptive filtering that the global hemodynamic modulation signals can be effectively removed from the fNIRS measuring cortical hemodynamic response. While pediatric subjects were performing a finger tapping task, we concurrently recorded cardiac pulsation and …

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Durability Studies On Stabilization Effectiveness Of Soils Containing Different Fractions Of Montmorillonite, Aravind Pedarla Jan 2009

Durability Studies On Stabilization Effectiveness Of Soils Containing Different Fractions Of Montmorillonite, Aravind Pedarla

Civil Engineering Theses - Archive

Stabilization of clays with additives like lime and cement has been practiced for several years and worked well in improving the subgrades. Though this practice is used widely, there were cases where the treated subgrades exhibited premature failures. Many departments of transportation (DOT) agencies in the United States have had subgrade failures even after stabilization with chemical additives due to loss of stabilizer over a time period, or a stabilizer being ineffective in some soils. The design based on PI and gradation of soil followed by many DOTs is quite misleading due to the lack of inclusion of basic soil …

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Failure Analysis Of A Mechanically Stabilized Earth (Mse) Wall Using Finite Element Program Plaxis, Tahsina Mahmood Jan 2009

Failure Analysis Of A Mechanically Stabilized Earth (Mse) Wall Using Finite Element Program Plaxis, Tahsina Mahmood

Civil Engineering Theses - Archive

Mechanically Stabilized Earth (MSE) retaining walls have been increasingly used in many federal, state and private projects over the last 20 years. MSE walls are reliable, constructible, and cost effective. However, failure of MSE wall has become a problem for all agencies using them. This study presents the failure analysis of a segmental block, MSE retaining wall located in Rockville, Maryland. The top of MSE wall moved about 12 inches to 18 inches. An extensive geotechnical investigation program was undertaken to investigate the MSE wall failure. This study presents the results of investigations to determine the causes of failure. The …

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Spatiotemporal Measurement Of Freezing-Induced Deformation Of Engineered Tissues, Ka Yaw Teo Jan 2009

Spatiotemporal Measurement Of Freezing-Induced Deformation Of Engineered Tissues, Ka Yaw Teo

Bioengineering Theses - Archive

In order to cryopreserve functional engineered tissues (ETs), the microstructure of extracellular matrix (ECM) as well as the cellular viability should be maintained given that the functionality of ETs is closely related to the ECM microstructure. Since the post-thaw ECM microstructure is determined by the deformation of ETs during cryopreservation, the freezing-induced deformation of ETs was measured in the present study with a newly developed quantum dot (QD)-mediated cell image deformetry technique using dermal equivalents as a model system. The dermal equivalents were constructed by seeding QD-labeled fibroblasts in type I collagen matrices. After 24 hour incubation, the ETs were …

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Development And Benefits Of A Leed Project Management Database, Teri Schmig Jan 2009

Development And Benefits Of A Leed Project Management Database, Teri Schmig

Civil Engineering Theses - Archive

The U.S. Green Building Council is a non-profit community of industry leaders working to make green buildings available to everyone. The documentation process for achieving Leadership in Energy and Environmental Design (LEED® ) certification is highly complex and more time-consuming than necessary with currently employed systems. This thesis explains the need for development of a relational database as a means to increase the efficiency of the documentation process to meet LEED® requirements. This database will provide the construction project team a relational platform that guides the user through the LEED® administration and certification process. By developing a LEED® specific project …

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Development Of Microscope Stage Incubator For Long-Term Monitoring Of Neuronal Cell Culture During Axotomy, Kailash Karthikeyan Jan 2009

Development Of Microscope Stage Incubator For Long-Term Monitoring Of Neuronal Cell Culture During Axotomy, Kailash Karthikeyan

Bioengineering Theses - Archive

It is imperative to understand the patterns in regeneration of the central and peripheral nervous system after injury. This understanding would provide a fundamental cue towards molecules and other factors involved in regeneration, and how they affect the regeneration pattern after injury. In most culturing techniques currently used for neuronal culturing and observing the neuronal regeneration, it is difficult to determine the regeneration pattern (individual axonal level) though the overall regeneration is observed due to the complexity of neuronal network. Thus a model that provides isolation of individual axons and allowing us to monitor continuously upon injury has been developed. …

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Controlled Vascular Cellular Growth By Microstructured Patterned Surfaces On Implantable Biodegradable Polymer Scaffold., Nitin Garg Jan 2009

Controlled Vascular Cellular Growth By Microstructured Patterned Surfaces On Implantable Biodegradable Polymer Scaffold., Nitin Garg

Bioengineering Theses - Archive

The technological advances in the field of MEMS and biodegradable polymers with elastomeric properties have opened new areas of application for engineering of soft tissues such as blood vessel, heart valves, cartilage, tendon, and bladder, which exhibit elastic properties. In this thesis work, Microfabrication technology has successfully been applied to biodegradable polymer films to encourage cell growth in designated area. This work is presented with the final goal of fabricating implantable polymer scaffolds to produce small diameter blood vessels in a controlled manner spatially by using the concept of wettability and contact guidance.There are several methods to control cell growth …

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Molecular Modelling Of Dna Translocation In Bio-Functionalized Nanopores With Applications In Gene Sequencing, Abhijit Ramachandran Jan 2009

Molecular Modelling Of Dna Translocation In Bio-Functionalized Nanopores With Applications In Gene Sequencing, Abhijit Ramachandran

Bioengineering Theses - Archive

The human genome project which was completed in 2003 took more than 12 years to complete at a cost of $2.7 billion. The advancement in technologies in the next five years led to the same feat being achieved in 5 months with a total cost of $1.5 million. Micro-fabrication technology has now made it possible miniaturize to micro- and nanofluidic devices for biochemical analysis. Solid-state nanopore based molecular analysis provides the potential to characterize and sequence DNA, based on the signature of the ionic current measured. A major challenge in using solid-state nanopores for DNA detection and sequencing is the …

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Development Of Brownfield Database Using Gis, Jubair Hossain Jan 2009

Development Of Brownfield Database Using Gis, Jubair Hossain

Civil Engineering Theses - Archive

Brownfields are abandoned, idled or underutilized industrial or commercial sites where expansion or redevelopment is complicated by actual or perceived environmental contamination. Brownfields may be as small as a vacant city lot or as large as an abandoned manufacturing facility occupying several hundred acres. The extent of contamination encountered at brownfield sites may range from minor surface debris to extensive, dangerous soil and ground-water contamination. Concerning the communities in which brownfields are located, redevelopment may improve community appearance and image, relieve associated health and environmental concerns and produce a beneficial economic effect through increased property values and employment opportunities.The overall …

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Modeling And Characterization Of Rf Mems Resonators, Najla S. Khan Jan 2009

Modeling And Characterization Of Rf Mems Resonators, Najla S. Khan

Electrical Engineering Theses - Archive

Over the past decade, a multitude of micro-electro-mechanical (MEMS) devices have been developed and commercialized due to their low power consumption, reduced cost and compact size. In recent years, significant advancements in technology have extended MEMS development towards radio frequency, microwave and millimeter wave applications. The need for micro-machining and MEMS based systems for RF and microwave applications arises from the inherent limitations of existing RF devices. Motivation for incorporating MEMS based fabrication technologies into microwave and millimeter wave systems can be classified into three main categories: precision, system integration and performance. As frequency increases, the size of RF components …

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Preparation Of Pyramidal Zinc Oxide Particle As An Antireflective Coating For Application In Solar Cell., Amit Banik Jan 2009

Preparation Of Pyramidal Zinc Oxide Particle As An Antireflective Coating For Application In Solar Cell., Amit Banik

Electrical Engineering Theses - Archive

There is a lot of research going on in the field of solar cell to increase the energy conversion efficiency. Many new methods have been implemented and new processes and materials have been suggested in the recent past. This research deals with the preparation of pyramidal structure zinc oxide particles as an antireflective coating for polycrystalline and non-silicon solar cell. The process involved a cost effective method that is electrochemical deposition of zinc oxide on silicon mold. The mold, inverted pyramid, is prepared by photolithographic process PECVD silicon nitride as the hard mask and wet etching and then electrochemical deposition …

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Design Of Microwave Non-Redundant Band-Pass Filter Using Microstrip And Edge Coupled Sections, Vinoj Vijayan Pillai Jan 2009

Design Of Microwave Non-Redundant Band-Pass Filter Using Microstrip And Edge Coupled Sections, Vinoj Vijayan Pillai

Electrical Engineering Theses - Archive

Microwave filler design using the non-redundant method relies on using the quarter wave Unit Elements (U.E's) to create a complex pole and hence augment the filter skirt response as against the redundant method wherein the U.E's do not contribute towards the filtering action. Filters realized using this method may have series high impedance capacitors, which are not realizable in planar microstrip technology. This thesis proposes a method to integrate microstrip transmission line and coupled line elements to circumvent the problem of realizing series capacitance. The total number of transmission line elements required to realize the filter is the minimum number …

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Performance Analysis Of Space - Time Block Coded Multiple Antenna Systems, Varsha Rao Bolar Jan 2009

Performance Analysis Of Space - Time Block Coded Multiple Antenna Systems, Varsha Rao Bolar

Electrical Engineering Theses - Archive

Multiple input and multiple output(MIMO) communications are seen as key technology to achieve high data rates for next generation of air interfaces like Wifi, WiMAX, and 3GPP-LTE, because of the spatial dimension complementing time (TDM), frequency (FDM), and code (CDM) multiple access technologies. MIMO technology has many captivating characteristics such as, it offers significant increases in data throughput and link range without additional bandwidth or transmit power. It achieves this by higher spectral efficiency (more bits per second per hertz of bandwidth) and diversity (reduced fading). Because of these properties, MIMO is a current theme of international wireless research. Diversity …

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A Portable Biotelemeter For Batteryless Gerd Sensors, Sandeep Battula Jan 2009

A Portable Biotelemeter For Batteryless Gerd Sensors, Sandeep Battula

Electrical Engineering Theses - Archive

In many medical problems, a continuous monitoring of the disease in vivo is essential to prevent further deterioration of health. The monitoring usually exceeds 24 hours. With the help of current advanced technologies, micro-medical devices are built to sense the internal physiological conditions in patients. Telemetry is used to transmit information to an external monitoring device. For the convenience and comfort of the patient, these monitoring systems should have low power consumption and be portable. This work discusses the design of a low power portable biotelemeter for batteryless Gastro esophageal reflux disease (GERD) sensors which can detect acid and non-acid …

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Analysis And Modeling Of Self Heating In Silicon Germanium Heterojunction Bipolar Transistors, Kevin Bastin Jan 2009

Analysis And Modeling Of Self Heating In Silicon Germanium Heterojunction Bipolar Transistors, Kevin Bastin

Electrical Engineering Theses - Archive

Silicon Germanium (SiGe) hetero junction bipolar transistors (HBTs) have established itself as strong technology contender for a host of circuit applications including analog, mixed signal and Radio Frequency (RF). Due to the effect of technology scaling, self heating plays a significant role in the performance of SiGe HBTs. This thesis paper does an extensive analysis on the effect of self heating and uses different methods to extract the self heating parameters. An expression for thermal resistance considering thermal conductivity as a function of temperature is derived. Also a method to convert a multi pole thermal model to a single pole …

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Preliminary Investigation Of Six Degree Of Freedom Human Steadiness Measurement Using A Performance Theory Framework, Jonathan Daniel Armstrong Jan 2009

Preliminary Investigation Of Six Degree Of Freedom Human Steadiness Measurement Using A Performance Theory Framework, Jonathan Daniel Armstrong

Electrical Engineering Theses - Archive

Tremor is an undesired oscillatory movement of a body segment which limits a person's ability to accomplish tasks. A conceptually sound, single number measure reflecting steadiness (defined as the inverse of tremor) of body segment is desired. Technology has advanced to make six degree of freedom (DOF) characterization of motion feasible, but the challenge remains regarding how to process time series data from multiple DOFs to achieve the single number composite measure. Previous conceptual work has applied General Systems Performance Theory (GSPT) to this problem. This thesis reports the investigation of steadiness composite measure formation. Three composite formation candidates were …

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Analysis Of The Spatial Correlation Measurements For The Multiple Input Multiple Output (Mimo) Channel Using Anechoic Chamber Measurement Methodologies To Evaluate Over-The-Air (Ota) Testing Techniques, Digvijay Arjunrao Jadhav Jan 2009

Analysis Of The Spatial Correlation Measurements For The Multiple Input Multiple Output (Mimo) Channel Using Anechoic Chamber Measurement Methodologies To Evaluate Over-The-Air (Ota) Testing Techniques, Digvijay Arjunrao Jadhav

Electrical Engineering Theses - Archive

There are numerous constraints in defining an Over-The-Air (OTA) test due to the practical hardware restrictions present in an anechoic chamber. It is necessary to evaluate the test signals used in OTA testing to verify that the real world multipath propagation can be recreated for OTA testing inside an anechoic chamber. The objective of this measurement is to check whether the parameter, `Spatial Correlation' can be used to compare OTA test signals used in the MIMO OTA testing. Spatial Correlation has prime importance from the point of view of MIMO channel modeling. It's a key factor in determining the MIMO …

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Error Concealment Techniques In H.264/Avc For Video Transmission Over Wireless Networks, Vineeth Shetty Kolkeri Jan 2009

Error Concealment Techniques In H.264/Avc For Video Transmission Over Wireless Networks, Vineeth Shetty Kolkeri

Electrical Engineering Theses - Archive

Several error concealment methods are applied to H.264/AVC (Advanced Video Coding) baseline profile such that the decoded video is error free. The error concealment techniques are implemented both in the spatial and temporal domains. The original and error concealment video sequences are compared in terms of MSE (Mean Square Error), PSNR (Peak-to-peak Signal to Noise Ratio) and SSIM (Structural Similarity Index Metric). This comparision has demonstrated that the error concealment methods are very effective in improving the visual quality. Implementation complexity also has been considered as the video transmission in baseline profile is meant for wireless networks.

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An Efficient Piecewise Linear Network, Rohit Rawat Jan 2009

An Efficient Piecewise Linear Network, Rohit Rawat

Electrical Engineering Theses - Archive

A Piecewise Linear Network (PLN) is a local network that offers the accuracy of higher order networks and the Multi Layer Perceptron (MLP), with the computational simplicity of linear networks. A method to design a PLN is demonstrated and several clustering algorithms, used in the design procedure, are compared. The performance of the Self Organizing Map (SOM) clustering algorithm has been found to be slightly better than the other clustering methods. Methods to determine the appropriate threshold in the Sequential Leader algorithm have been studied. A binary search based approach was found to be the most efficient in terms of …

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A Frequency Domain Approach For Time-Reversal Of Microwave Impulses, Shaoshu Sha Jan 2009

A Frequency Domain Approach For Time-Reversal Of Microwave Impulses, Shaoshu Sha

Electrical Engineering Theses - Archive

In this thesis, a compact and low-cost electronic circuit system is designed for time-reversal of microwave impulses with nanosecond and sub-nanosecond temporal durations. A frequency domain approach is adopted in order to avoid high sampling rate in time. The proposed system obtains the discrete spectra of input impulses first, then realizes time-reversal in frequency domain, and finally synthesizes the time-reversed impulses using discrete continuous wave elements. It is composed of commercially available circuits including oscillators, mixers/multipliers, band-pass-filters, amplifiers, and switches, hence embodies low-cost system-on-chip implementation. The proposed time-reversal circuit's performance is verified by Advanced Design System (ADS) simulations, with most …

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Utilizing Physical Layer Information To Improve Rfid Tag Identification, Rushikesh Shree Khasgiwale Jan 2009

Utilizing Physical Layer Information To Improve Rfid Tag Identification, Rushikesh Shree Khasgiwale

Electrical Engineering Theses - Archive

Radio-frequency identification (RFID) systems are designed for fast and accurate identification of multiple RFID tags. Their performance depends on the effective detection andresolution of communication collisions caused by the presence of multiple tags in the reader's field. Present RFID protocols do not rely upon the received physical waveform obtainedduring a collision for either collision resolution or improved identification rate. This signal contains important information that is often ignored or otherwise discarded.In this thesis I analyze the physical layer information extracted from a collision waveform from the ISO-18000-6C protocol and identifypotentially performance enhancing information contained therein. Utilization of this information to …

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Athena - Rfid Tag Metrics, Amit Jain Jan 2009

Athena - Rfid Tag Metrics, Amit Jain

Electrical Engineering Theses - Archive

In this thesis we have developed a Metric which is a numerical value representing the readability and performance characteristic of an RFID tagged object. The metric value ranges from 0 -100 and is given a unit of Athena, where a higher number specifies a better performing tag. The major parameters on which the metric value depends are frequency at which RFID system is working, transmitted power by the reader, and the received signal strength from the tag. All the parameters used for the Metric evaluation are well within the FCC regulations for passive UHF RFID system. Choosing the best performing …

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Localization System For Uav/Ugv In Urban Environments, Vishal Savio Coelho Jan 2009

Localization System For Uav/Ugv In Urban Environments, Vishal Savio Coelho

Electrical Engineering Theses - Archive

An implementation of relative localization of wireless sensor nodes using a potential field method is presented in this work. The system is designed to assist in UAV/UGV navigation in urban environments like rooms and passageways of buildings. An unmanned vehicle will need to rely on ground-based sensors to help it navigate indoors, as GPS signals are severely attenuated and reception is intermittent.A sufficient number of sensors are first deployed throughout the terrain in a random fashion. They must then localize themselves to the environment, i.e. they must develop an internal frame of reference or co-ordinate system. A potential field method …

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Effects Of Cyclic Strain And Growth Factors On Vascular Smooth Muscle Cell Responses, Kytai Truong Nguyen, Hao Xu Jan 2009

Effects Of Cyclic Strain And Growth Factors On Vascular Smooth Muscle Cell Responses, Kytai Truong Nguyen, Hao Xu

Bioengineering Faculty Publications - Archive

Under physiological and pathological conditions, vascular smooth muscle cells (SMC) are exposed to different biochemical factors and biomechanical forces. Previous studies pertaining to SMC responses have not investigated the effects of both factors on SMCs. Thus, in our research we investigated the combined effects of growth factors like bFGF (basic fibroblast growth factor), TGF-�� (transforming growth factor ��) and PDGF (platelet-derived growth factor) along with physiological cyclic strain on SMC responses. Physiological cyclic strain (10% strain) significantly reduced SMC proliferation compared to static controls while addition of growth factors bFGF, TGF-�� or PDGF-AB had a positive influence on SMC growth …

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Topology Optimization Using Hyper Radial Basis Function Network, Aditya P. Apte Jan 2009

Topology Optimization Using Hyper Radial Basis Function Network, Aditya P. Apte

Mechanical and Aerospace Engineering Dissertations - Archive

Topology optimization has been conventionally used in automobile and aerospace industries to produce lightweight structures for minimum compliance or maximum fundamental frequency. Today, topology optimization finds application in solving diverse types of problems ranging from medicine to consumer products. Popular continuum based method SIMP fails to provide global solution due to too many variables involved. In this work, a novel hyper radial basis function network is presented as topology description function. The proposed approach provides drastic reduction in number of design variables involved in topology optimization. This makes the use of heuristic global solution possible. Parallel processing, reanalysis formulation and …

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Optimal-Control Theoretic Methods For Optimization And Regulation Of Distributed Parameter Systems, Jennifer Dawn Goss Jan 2009

Optimal-Control Theoretic Methods For Optimization And Regulation Of Distributed Parameter Systems, Jennifer Dawn Goss

Mechanical and Aerospace Engineering Dissertations - Archive

Optimal control and optimization of distributed parameter systems are discussed in the context of a common control framework. The adjoint method of optimization and the traditional linear quadratic regulator implementation of optimal control both employ adjoint or costate variables in the determination of control variable progression. As well both theories benefit from a reduced order model approximation in their execution. This research aims to draw clear parallels between optimization and optimal control utilizing these similarities. Several applications are presented showing the use of adjoint/costate variables and reduced order models in optimization and optimal control problems. The adjoint method for shape …

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Transient Flow Analysis Of Filling In Pulse Detonation Engine, Veera Venkata Suneel Jinnala Jan 2009

Transient Flow Analysis Of Filling In Pulse Detonation Engine, Veera Venkata Suneel Jinnala

Mechanical and Aerospace Engineering Theses - Archive

The Pulse Detonation Engine (PDE) is considered to be a propulsion system of future air vehicles. The objective of the present study is to model an efficient inlet system for filling the detonation tube completely with the fuel/air mixture. In the present study the filling processes is modeled numerically using CFD code FLUENTTM. Calculations for the gas flow are carried out by solving the Navier-Stokes equations coupled with the k- ? turbulence model. Five different inlet configurations were proposed and simulated in both two-dimensionally and three-dimensionally. The model with an orifice plate at the inlets ensured the desired optimum results. …

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Guidance Of Receiver Aircraft To Rendezvous With Tanker In The Presence Of Wind, Jane-Wit Kampoon Jan 2009

Guidance Of Receiver Aircraft To Rendezvous With Tanker In The Presence Of Wind, Jane-Wit Kampoon

Mechanical and Aerospace Engineering Theses - Archive

This thesis work addresses the problem of aircraft rendezvous in the presence of prevailing wind for automated aerial refueling operations. A modified point-parallel rendezvous procedure is defined. The tanker aircraft performs a racetrack maneuver along a pre-specified refueling orbit. The receiver aircraft enters the refueling area through a fixed point and flies along the refueling line that is aligned with on of the straight legs of the race track. It is the responsibility to meet the tanker at the rendezvous point. A virtual target is used to define the trajectory of the refueling orbit. A nonlinear guidance algorithm is used …

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Experimental Investigation Of Flow Boiling And Spray Cooling On Enhanced Surfaces In Fc-72, Gilberto Morenp Jan 2009

Experimental Investigation Of Flow Boiling And Spray Cooling On Enhanced Surfaces In Fc-72, Gilberto Morenp

Mechanical and Aerospace Engineering Dissertations - Archive

In this study the effect of a recently developed, thermally conductive microporous coating on flow boiling and spray cooling performance was studied using FC-72 as the working fluid. The overall goal is to further increase heat transfer in forced convection systems and in doing so, provide a viable option for future cooling applications. In flow boiling, the coating increased heat transfer coefficients by as much as 400% and produced values exceeding 40,000 W-m-2 K-1. This enhancement is believed to be a result of both an increase in active nucleation sites and a decrease of the superheated liquid layer. It is …

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A Comprehensive Study Of Recycled Concrete Aggregates As A Drainable Base Layer For Pavements, Juan Bosquez Jan 2009

A Comprehensive Study Of Recycled Concrete Aggregates As A Drainable Base Layer For Pavements, Juan Bosquez

Civil Engineering Dissertations - Archive

The use of recycled materials in construction is becoming increasingly popular due to the shortage of raw materials. Coupled with the environmental concerns surrounding the quarrying of natural minerals, waste materials are being considered as viable replacement sources. By recycling waste materials, available landfill space is increased and costs of transportation are reduced. This dissertation study was conducted to evaluate the use of recycled concrete aggregates as flexible base as per the requirements of the Texas Department of Transportation (2004). Two sources of recycled aggregates and one source of natural limestone aggregate were collected from the Dallas/Fort Worth Area and …

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