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2010

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Articles 1111 - 1140 of 5375

Full-Text Articles in Engineering

Opportunistic Relaying For Multi-Antenna Cooperative Decode-And-Forward Relay Networks, Weiliang Zeng, Chengshan Xiao, Youzheng Wang, Jianhua Lu Aug 2010

Opportunistic Relaying For Multi-Antenna Cooperative Decode-And-Forward Relay Networks, Weiliang Zeng, Chengshan Xiao, Youzheng Wang, Jianhua Lu

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, we investigate the relaying scheme for multi-antenna cooperative networks without channel state information at the transmitters. It is shown that the classic opportunistic relaying scheme, which allows only one relay node to forward the message, may lead to significant loss when it is extended to the corresponding multi-antenna relay scenarios. a generalized opportunistic relaying approach, which selects more transmit antennas distributed on multiple relay nodes to transmit data simultaneously, is proposed to maximize the network throughput via balancing the source-relay and the relay-destination channels. Numerical examples show the large impact of multiple antennas and relays on the …

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Low-Complexity Turbo Block Decision Feedback Equalization For Mimo Systems, Jun Tao, Jingxian Wu, Yahong Rosa Zheng Aug 2010

Low-Complexity Turbo Block Decision Feedback Equalization For Mimo Systems, Jun Tao, Jingxian Wu, Yahong Rosa Zheng

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a low-complexity turbo block decision feedback equalizer (BDFE) with reliability-Based successive soft interference cancellation (SSIC) for multiple-input multiple-output (MIMO) systems. Turbo equalization in MIMO systems needs to combat both InterSymbol interference (ISI) due to frequency-selective fading and multiplexing interference (MI) among data streams transmitted by different antennas. the proposed MIMO BDFE performs SSIC on both ISI in the time domain and MI in the space domain. for an SSIC receiver, the order in which the symbols are detected and canceled is critical to the system performance, yet it is often overlooked in the literature. We propose a …

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Layered Frequency-Domain Turbo Equalization For Single Carrier Broadband Mimo Systems, Jian Zhang, Yahong Rosa Zheng, Jingxian Wu Aug 2010

Layered Frequency-Domain Turbo Equalization For Single Carrier Broadband Mimo Systems, Jian Zhang, Yahong Rosa Zheng, Jingxian Wu

Electrical and Computer Engineering Faculty Research & Creative Works

A new layered frequency-domain turbo equalization (LFDTE) scheme is proposed for single carrier (SC) multiple input multiple-output (MIMO) systems. the proposed scheme combines the respective advantages of layered detection and turbo equalization to further lower the bit error rate (BER) for high-data-rate communications. Different from the traditional frequency-domain turbo equalization (FDTE) method for MIMO systems, our new detection algorithm employs a layered structure in each turbo iteration, and at each layer a group of best data streams is detected in the form of soft symbols and then canceled from the received signals in frequency domain. the extrinsic information for the …

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Confining An Organic Molecule In A Nanocavity: Effect On Rotational/Vibrational Motion And Its Consequence For Spin Dephasing., Lopamudra Das Aug 2010

Confining An Organic Molecule In A Nanocavity: Effect On Rotational/Vibrational Motion And Its Consequence For Spin Dephasing., Lopamudra Das

Theses and Dissertations

Recently, it was found that the strongly temperature-dependent spin dephasing time of bound electrons in the organic molecule tris(8-hydroxyquinoline aluminum), or Alq3, increases when a few of these molecules are confined within 1-2 nm sized nanocavities in porous alumina. What causes this increase is not well understood, but one possibility is that the rotational/vibrational modes of the molecule are altered inside a nanocavity, leading to suppression of spin coupling with these modes and a concomitant increase in the spin dephasing time. To test this possibility, we have carried out mid-infrared spectroscopy of few molecule clusters confined within 1-2 nm sized …

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Solving Multi-Scale Low Frequency Electromagnetic Problems, Zhi Guo Qian, Mao Kun Li, Zu Hui Ma, Li (Lijun) Jun Jiang, Weng Cho Chew Aug 2010

Solving Multi-Scale Low Frequency Electromagnetic Problems, Zhi Guo Qian, Mao Kun Li, Zu Hui Ma, Li (Lijun) Jun Jiang, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, we will discuss two methods to tackle the low-frequency, multi-scale electromagnetics problem. First we will discuss the augmented electric field integral equation (AEFIE), and then, we will discuss the equivalence principle algorithm (EPA). The AEFIE allows the solution of such problems without the need to perform a loop search of a complex structure. The EPA allows the separation of circuit physics from wave physics in a multiscale problem. Hybridization of these two methods will be discussed.

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Tracking Simultaneous Time-Varying Power Harmonic Distortions Using Filter Banks, Carlos A. Duque, Paulo M. Silveira, Thomas L. Baldwin, Paulo F. Ribeiro Aug 2010

Tracking Simultaneous Time-Varying Power Harmonic Distortions Using Filter Banks, Carlos A. Duque, Paulo M. Silveira, Thomas L. Baldwin, Paulo F. Ribeiro

University Faculty Publications and Creative Works

Although it is well known that the Fourier analysis is only accurately applicable to steady-state waveforms, it is a widely used tool to study and monitor time-varying signals, such as are commonplace in electrical power systems. The disadvantages of the Fourier analysis, such as frequency spillover or problems due to sampling (data window) truncation can often be minimized by various windowing techniques, but they nevertheless exist. This paper demonstrates that it is possible to track and visualize amplitude and time-varying power systems harmonics, without frequency spillover caused by classical time-frequency techniques. This new tool allows for a clear visualization of …

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Development Of Streamflow Projections Under Changing Climate Conditions Over Colorado River Basin Headwaters, W. P. Miller, Thomas C. Piechota, S. Gangopadhyay, T. Pruitt Aug 2010

Development Of Streamflow Projections Under Changing Climate Conditions Over Colorado River Basin Headwaters, W. P. Miller, Thomas C. Piechota, S. Gangopadhyay, T. Pruitt

Civil and Environmental Engineering and Construction Faculty Research

The current drought over the Colorado River Basin has raised concerns that the US Department of the Interior, Bureau of Reclamation (Reclamation) may impose water shortages over the lower portion of the basin for the first time in history. The guidelines that determine levels of shortage are affected by forecasts determined by the Colorado Basin River Forecast Center (CBRFC). While these forecasts by the CBRFC are useful, water managers within the basin are interested in long-term projections of streamflow, particularly under changing climate conditions. In this study, a bias-corrected, statistically downscaled dataset of projected climate is used to force a …

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Comparison Of Winter Temperature Profiles In Asphalt And Concrete Pavements, Jeremy Brooks Dye Aug 2010

Comparison Of Winter Temperature Profiles In Asphalt And Concrete Pavements, Jeremy Brooks Dye

Theses and Dissertations

Because winter maintenance is so costly, Utah Department of Transportation (UDOT) personnel asked researchers at Brigham Young University to determine whether asphalt or concrete pavements require more winter maintenance. Differing thermal properties suggest that, for the same environmental conditions, asphalt and concrete pavements will have different temperature profiles. Climatological data from 22 environmental sensor stations (ESSs) near asphalt roads and nine ESSs near concrete roads were used to 1) determine which pavement type has higher surface temperatures in winter and 2) compare the subsurface temperatures under asphalt and concrete pavements to determine the pavement type below which more freeze-thaw cycles …

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Long-Range Pollution Transport During The Milagro-2006 Campaign: A Case Study Of A Major Mexico City Outflow Event Using Free-Floating Altitude-Controlled Balloons, P. B. Voss, R. A. Zaveri, F. M. Flocke, H. Mao, T. P. Hartley, P. Deamicis, I. Deonandan, G. Contreras-Jiménez, O. Martínez-Antonio, M. Figueroa Estrada, D. Greenberg, T. L. Campos, A. J. Weinheimer, D. J. Knapp, D. D. Montzka, J. D. Crounse, P. O. Wennberg, E. Apel, S. Madronich, B. De Foy Aug 2010

Long-Range Pollution Transport During The Milagro-2006 Campaign: A Case Study Of A Major Mexico City Outflow Event Using Free-Floating Altitude-Controlled Balloons, P. B. Voss, R. A. Zaveri, F. M. Flocke, H. Mao, T. P. Hartley, P. Deamicis, I. Deonandan, G. Contreras-Jiménez, O. Martínez-Antonio, M. Figueroa Estrada, D. Greenberg, T. L. Campos, A. J. Weinheimer, D. J. Knapp, D. D. Montzka, J. D. Crounse, P. O. Wennberg, E. Apel, S. Madronich, B. De Foy

Engineering: Faculty Publications

One of the major objectives of the Megacities Initiative: Local And Global Research Observations (MILAGRO-2006) campaign was to investigate the long-range transport of polluted Mexico City Metropolitan Area (MCMA) outflow and determine its downwind impacts on air quality and climate. Six research aircraft, including the National Center for Atmospheric Research (NCAR) C-130, made extensive chemical, aerosol, and radiation measurements above MCMA and more than 1000 km downwind in order to characterize the evolution of the outflow as it aged and dispersed over the Mesa Alta, Sierra Madre Oriental, Coastal Plain, and Gulf of Mexico. As part of this effort, free-floating …

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A Monocular Marker-Free Gait Measurement System, Jane Courtney, Annraoi M. De Paor Aug 2010

A Monocular Marker-Free Gait Measurement System, Jane Courtney, Annraoi M. De Paor

Articles

This paper presents a new, user-friendly, portable motion capture and gait analysis system for capturing and analyzing human gait, designed as a telemedicine tool to monitor remotely the progress of patients through treatment. The system requires minimal user input and simple single-camera filming (which can be acquired from a basic webcam) making it very accessible to nontechnical, nonclinical personnel. This system can allow gait studies to acquire a much larger data set and allow trained gait analysts to focus their skills on the interpretation phase of gait analysis. The design uses a novel motion capture method derived from spatiotemporal segmentation …

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Rapid Cell Extraction In Aqueous Two-Phase Microdroplet Systems, Kalpana Vijayakumar, Shelly Gulati, Andrew J. De Mello, Joshua B. Edel Aug 2010

Rapid Cell Extraction In Aqueous Two-Phase Microdroplet Systems, Kalpana Vijayakumar, Shelly Gulati, Andrew J. De Mello, Joshua B. Edel

All Faculty Articles - School of Engineering and Computer Science

Distinguishing specific cells is an essential technique in cell research and clinical diagnostics. We report a novel method to passively isolate and extract cells in a microfluidic device. We utilise a droplet-based microfluidic system to generate an aqueous two phase system in which aqueous droplets consist of two phases in the form of a double emulsion. Specifically, we generate PEG droplets that completely encapsulate DEX droplets within a microfluidic channel. Target cells can be introduced directly into the droplets and driven to partition to the more favourable phase, whilst still being contained within the aqueous droplet. Human T lymphoma cells, …

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Computer Aided Contour Profiling Of High Strength Deposits, Sriram Praneeth Isanaka, Amar Bala Sridhar, Frank W. Liou, Joseph William Newkirk Aug 2010

Computer Aided Contour Profiling Of High Strength Deposits, Sriram Praneeth Isanaka, Amar Bala Sridhar, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Additive manufacturing processes suffer from the effect of ripples, edge rounding and surface variations. To reduce their effect, ideal process parameters for the laser deposition process were investigated. Also, a new method was identified to analyze deposits by accurately plotting their contours. This was achieved through point cloud data of the deposits generated using coordinate measurement and 3D scanning. Curve fitting was performed on the data in Matlab to generate the contours of the deposit. The intercept values, heights, and contact angle of the curves give an indication of the uniformity of deposits and aid in reducing defects.

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Freeze Extrusion Fabrication Of 13-93 Bioactive Glass Scaffolds For Bone Repair, Tieshu Huang, Nikhil D. Doiphode, M. N. Rahaman, Ming-Chuan Leu, B. Sonny Bal, D. E. Day Aug 2010

Freeze Extrusion Fabrication Of 13-93 Bioactive Glass Scaffolds For Bone Repair, Tieshu Huang, Nikhil D. Doiphode, M. N. Rahaman, Ming-Chuan Leu, B. Sonny Bal, D. E. Day

Materials Science and Engineering Faculty Research & Creative Works

There is an increasing demand for synthetic scaffolds with the requisite biocompatibility, internal architecture, and mechanical properties for the bone repair and regeneration. In this work, scaffolds of a silicate bioactive glass (13-93) were prepared by a freeze extrusion fabrication (FEF) method and evaluated in vitro for potential applications in bone repair and regeneration. The process parameters for FEF production of scaffolds with the requisite microstructural characteristics, as well as the mechanical and cell culture response of the scaffolds were evaluated. After binder burnout and sintering (60 min at 700°C), the scaffolds consisted of a dense glass network with interpenetrating …

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Selective Laser Sintering Of 13-93 Bioactive Glass, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas, Mariano Garcia Velez Aug 2010

Selective Laser Sintering Of 13-93 Bioactive Glass, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas, Mariano Garcia Velez

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Bioactive glasses are more promising than biopolymers in fabricating scaffolds for bone tissue repair because they convert to hydroxyapatite, when implanted in vivo. Both direct and indirect selective laser sintering (SLS) methods of 13-93 bioactive glass were considered in this research to study the feasibility of fabricating scaffolds for bone repair applications. Stearic acid was used as the binder in the indirect method to fabricate the scaffolds. The green scaffolds underwent binder burnout and sintering at various soaking conditions between 675⁰C and 700⁰C, achieving a maximum compressive strength of 23.6 MPa, which is higher than that of the human cancellous …

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Laser Based Rapid Manufacturing Of Metallic Gas Diffusion Layers For Pem Fuel Cells, Gargi Tandra, Todd E. Sparks, Shyam Barua, Nikhil P. Kulkarni, Frank W. Liou Aug 2010

Laser Based Rapid Manufacturing Of Metallic Gas Diffusion Layers For Pem Fuel Cells, Gargi Tandra, Todd E. Sparks, Shyam Barua, Nikhil P. Kulkarni, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Gas Diffusion layers (GDL’s) are an essential component of Polymer Electrolyte Membrane Fuel cells (PEMFC’s) which aid in thermal & electrical conductivities, water management and act as backup layers for the membrane electrode assemblies. This paper summarizes the effort to prototype metallic GDL designs using a miniature laser deposition system developed at Missouri University of Science & Technology. The pore sizes are controlled by masking the diverging laser beam using stainless steel masks of varying sizes and shapes. The through pore feature and further treatment of the GDL’s for hydrophobicity reduces the water management issue and thereby increases the performance …

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Mea Manufacturing Using An Additive Manufacturing Process To Deposit A Catalyst Pattern In An Mea And Its Impact On Cost Reduction, Nikhil P. Kulkarni, Todd E. Sparks, Gargi Tandra, Frank W. Liou Aug 2010

Mea Manufacturing Using An Additive Manufacturing Process To Deposit A Catalyst Pattern In An Mea And Its Impact On Cost Reduction, Nikhil P. Kulkarni, Todd E. Sparks, Gargi Tandra, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The manufacturing of a fuel cell Membrane Electrode Assembly (MEA) is a significant cost driver in polymer-electrolyte membrane (PEM) fuel cell technologies, primarily due to the inclusion of expensive materials in the catalyst layer. The selective deposition of a catalyst on the MEA of a fuel cell can drastically reduce the costs depending upon the catalyst, method used for deposition, and production volume. In this paper, testing and analysis of a novel catalyst iridium oxide is discussed. The performance of the catalyst will be compared with the conventional catalysts which will give us an estimate of its effectiveness however, in …

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Multi-Axis Planning System (Maps) For Hybrid Laser Metal Deposition Processes, Frank W. Liou, Jianzhong Ruan, Todd E. Sparks Aug 2010

Multi-Axis Planning System (Maps) For Hybrid Laser Metal Deposition Processes, Frank W. Liou, Jianzhong Ruan, Todd E. Sparks

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper summarizes the research and development of a Multi-Axis Planning System (MAPS) for hybrid laser metal deposition processes. The project goal is to enable the current direct metal deposition systems to fully control and utilize multi-axis capability to make complex parts. MAPS allows fully automated process planning for multi-axis layered manufacturing to control direct metal deposition machines for automated fabrication. Such a capability will lead to dramatic reductions in lead time and manufacturing costs for high-value, low-volume components with high performance material. The overall approach, slicing algorithm, machine simulation for planning validation, and the planning results will be presented.

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Optimization Of Selective Laser Sintering Process For Fabrication Of Zirconium Diboride Parts, Ming-Chuan Leu, Shashwatashish Pattnaik, Greg Hilmas Aug 2010

Optimization Of Selective Laser Sintering Process For Fabrication Of Zirconium Diboride Parts, Ming-Chuan Leu, Shashwatashish Pattnaik, Greg Hilmas

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Selective Laser Sintering (SLS) was investigated to fabricate Zirconium Diboride (ZrB2) parts for ultra-high temperature applications. Experiments were conducted to determine values of SLS process parameters (laser power, scan speed, line spacing, and layer thickness) that can be used to build ZrB2 parts with high integrity and sharp geometrical features. A sacrificial plate with a proper number of layers (determined from experimentation) separated from the main part was built in order to reduce thermal gradients when building the main part. The sacrificial plate was found to assist in eliminating cracks in the bottom of the main part. …

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Influence Of Relative Compaction On Passive Resistance Of Abutments With Mechanically Stabilized Earth (Mse) Wingwalls, Alec N. Strassburg Aug 2010

Influence Of Relative Compaction On Passive Resistance Of Abutments With Mechanically Stabilized Earth (Mse) Wingwalls, Alec N. Strassburg

Theses and Dissertations

Large scale static lateral load tests were completed on a pile cap with wingwalls under several different sand backfill configurations: no backfill, loosely compacted unconfined, loosely compacted slip plane wall confined, loosely compacted MSE wingwall confined, and densely compacted MSE wingwall confined. The relative compaction of the backfill was varied during each test to observe the change in passive resistance provided by the backfill. The wall types were varied to observe the force placed on the walls and the wall displacement as a result of the laterally loaded pile cap and backfill relative compaction. Passive force-displacement curves were generated from …

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Channel Equalization For Single Carrier Mimo Underwater Acoustic Communications, Chengshan Xiao, Jun Tao, Yahong Rosa Zheng, T. C. Yang, Wen Bin Yang Aug 2010

Channel Equalization For Single Carrier Mimo Underwater Acoustic Communications, Chengshan Xiao, Jun Tao, Yahong Rosa Zheng, T. C. Yang, Wen Bin Yang

Electrical and Computer Engineering Faculty Research & Creative Works

Multiple-input multiple-output (MIMO) underwater acoustic (UWA) channels introduce both space-time interference (STI) and time-varying phase distortion for transmitted signals. in such cases, the equalized symbols produced by conventional equalizer aiming for STI cancelation suffer phase rotation and thus cannot be reliably detected. in this paper, we propose a new equalization scheme for high data rate single carrier MIMO UWA channels. Different from existing methods employing joint equalization and symbol wise phase tracking technology, the proposed scheme decouples the interference cancelation (IC) operation and the phase compensation operation, leading to a generalized equalizer structure combining an IC equalizer with a phase …

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Development Of A Low Cost Imaging System For A Laser Metal Deposition Process, Shyam Barua, Todd E. Sparks, Frank W. Liou Aug 2010

Development Of A Low Cost Imaging System For A Laser Metal Deposition Process, Shyam Barua, Todd E. Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The size of the melt pool created by the laser is one of the most important quality characteristic in a laser metal deposition process. This paper discusses the development of a low-cost vision system to automatically determine the size of the melt pool for in-process control. To cope with the intense infrared signal from the laser and melt pool, external ultraviolet illumination is paired with narrow bandpass filters on a usb microscope to achieve a clear image of the melt pool. The sensitivity of the melt pool to changes in system parameters and various substrate materials are also evaluated.

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Effect Of Different Graphite Materials On Electrical Conductivity And Flexural Strength Of Bipolar Plates Fabricated By Selective Laser Sintering, Nannan Guo, Ming-Chuan Leu Aug 2010

Effect Of Different Graphite Materials On Electrical Conductivity And Flexural Strength Of Bipolar Plates Fabricated By Selective Laser Sintering, Nannan Guo, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Graphite is an excellent material for bipolar plates used in Proton Exchange Membrane (PEM) fuel cell due to its great chemical resistance, but the brittle nature makes it difficult to manufacture. Selective Laser Sintering (SLS) based on layer-by-layer manufacturing technology can fabricate graphite bipolar plates with complex gas flow channels. To improve the performance of bipolar plates including electrical conductivity and flexural strength, different graphite materials (natural graphite, synthetic graphite, carbon black, and carbon fiber) were investigated to fabricate test samples. These samples then went through post processing including carbonization and infiltration. The results show that bipolar plates with electrical …

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Selective Laser Sintering And Freeze Extrusion Fabrication Of Scaffolds For Bone Repair Using 13-93 Bioactive Glass: A Comparison, Krishna C. R. Kolan, Nikhil P. Doiphode, Ming-Chuan Leu Aug 2010

Selective Laser Sintering And Freeze Extrusion Fabrication Of Scaffolds For Bone Repair Using 13-93 Bioactive Glass: A Comparison, Krishna C. R. Kolan, Nikhil P. Doiphode, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

13-93 glass is a third-generation bioactive material which accelerates the bone’s natural ability to heal by itself through bonding with surrounding tissues. It is an important requirement for synthetic scaffolds to maintain their bioactivity and mechanical strength with a porous internal architecture comparable to that of a human bone. Additive manufacturing technologies provide a better control over design and fabrication of porous structures than conventional methods. In this paper, we discuss and compare some of the common aspects in the scaffold fabrication using two such processes, viz. selective laser sintering (SLS) and freeze extrusion fabrication (FEF). Scaffolds fabricated using each …

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Uncertainty Analysis In Laser Deposition Finish Machining Operations, Jomy Francis, Todd E. Sparks, Frank W. Liou Aug 2010

Uncertainty Analysis In Laser Deposition Finish Machining Operations, Jomy Francis, Todd E. Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Laser Aided Manufacturing Process (LAMP) from Missouri S&T is a laser based metals rapid manufacturing process that uses machining to improve the final part's surface finish. When free-form machining, the absence of enough deposited material results in inconsistent scallop heights which result in poor surface finish or incorrect geometry in the final part. This paper investigates a probabilistic approach to various uncertainties involved in the deposition and subsequent machining of an arbitrary part. Furthermore, this paper analyses the machine errors which makes the response of Scallop Height to exceed the predefined maximum scallop height when traveling along the tool …

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Low-Loss Hollow Waveguide Platforms For Optical Sensing And Manipulation, Evan J. Lunt Aug 2010

Low-Loss Hollow Waveguide Platforms For Optical Sensing And Manipulation, Evan J. Lunt

Theses and Dissertations

This dissertation presents a method for fabricating integrated hollow and solid optical waveguides on planar substrates. These waveguides are antiresonant reflecting optical waveguides (ARROWs), where high-index cladding layers confine light to hollow cores through optical interference. Hollow waveguides that can be filled with liquids or gases are an important new building block for creating highly-integrated optical sensors. The method developed for fabricating these integrated waveguides employs standard processes and materials used in the microelectronics industry, allowing for parallel, low-cost fabrication. Dielectric cladding layers are deposited on a silicon wafer using plasma-enhanced chemical vapor deposition (PECVD). After the lower cladding layers …

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Image Processing Algorithms For Diagnostic Analysis Of Microcirculation, Sumeyra Ummuhan Demir Aug 2010

Image Processing Algorithms For Diagnostic Analysis Of Microcirculation, Sumeyra Ummuhan Demir

Theses and Dissertations

Microcirculation has become a key factor for the study and assessment of tissue perfusion and oxygenation. Detection and assessment of the microvasculature using videomicroscopy from the oral mucosa provides a metric on the density of blood vessels in each single frame. Information pertaining to the density of these microvessels within a field of view can be used to quantitatively monitor and assess the changes occurring in tissue oxygenation and perfusion over time. Automated analysis of this information can be used for real-time diagnostic and therapeutic planning of a number of clinical applications including resuscitation. The objective of this study is …

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Development Of A Low Cost Autopilot System For Unmanned Aerial Vehicles, Jose Ortiz Aug 2010

Development Of A Low Cost Autopilot System For Unmanned Aerial Vehicles, Jose Ortiz

Theses and Dissertations

The purpose of this thesis was to develop a low cost autonomous flight control system for small unmanned aerial vehicles with the aim to support collaborative systems. A low cost hardware solution was achieved by careful selection of sensors, integration of hardware subsystems, and the use of new microcontroller technologies. Flight control algorithms to guide a vehicle though waypoint based flight paths and loiter about a point were implemented using direction fields. A hardware in the loop simulator was developed to ensure proper operation of all hardware and software components prior to flight testing. The resulting flight control system achieved …

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International Space Station Systems Engineering Case Study, Air Force Center For Systems Engineering, Bill Stockman, Joe Boyle, John Bacon Aug 2010

International Space Station Systems Engineering Case Study, Air Force Center For Systems Engineering, Bill Stockman, Joe Boyle, John Bacon

AFIT Documents

This case study on the International Space Station considers what many believe to have been the ultimate international engineering project in history. The initial plans involved the direct participation of 16 nations, 88 launches and over 160 spacewalks-more space activities than NASA had accomplished prior to the 1993 International Space Station decision. Probably more important was the significant leap in System Engineering (SE) execution that would be required to build and operate a multi-national space station. In a short period of time, NASA and its partners had to work out how to integrate culturally different SE approaches, designs, languages and …

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Quantitative And Qualitative Results From Droplet Impingement Experiments On Superhydrophobic Surfaces With Micro-Ribs For Three Liquid Types, John T. Pearson Aug 2010

Quantitative And Qualitative Results From Droplet Impingement Experiments On Superhydrophobic Surfaces With Micro-Ribs For Three Liquid Types, John T. Pearson

Theses and Dissertations

Experiments were performed in which liquid droplets were videographically recorded impacting horizontal superhydrophobic surfaces. The superhydrophobic surfaces were micropatterned with alternating ribs and cavities and coated with a hydrophobic coating. The following surface types were also tested for comparison: smooth uncoated, micropatterned uncoated, and smooth coated surfaces. Three liquid types were used: pure water, ethanol, and a 50/50 water/glycerine mixture. Acquired data demonstrated that the maximum droplet spread diameter exhibited a greater Weber number dependence than that previously reported in the literature. The time delays between impact and maximum spread and between impact and ejection of a vertical jet were …

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Thin Film Microfluidic And Nanofluidic Devices, Mark Noble Hamblin Aug 2010

Thin Film Microfluidic And Nanofluidic Devices, Mark Noble Hamblin

Theses and Dissertations

Lab-on-a-chip devices, also known as micro total analysis systems (μTAS), are implementations of chemical analysis systems on microchips. These systems can be fabricated using standard thin film processing techniques. Microfluidic and nanofluidic channels are fabricated in this work through sacrificial etching. Microchannels are fabricated utilizing cores made from AZ3330 and SU8 photoresist. Multi-channel electroosmotic (EO) pumps are evaluated and the accompanying channel zeta potentials are calculated. Capillary flow is studied as an effective filling mechanism for nanochannels. Experimental departure from the Washburn model is considered, where capillary flow rates lie within 10% to 70% of theoretical values. Nanochannels are fabricated …

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