Engineering Commons^™

A System For Collecting Data To Characterize A Pre-Fall Change In Sway: Development And Proof-Of-Concept Analyses, Amy Renae Sipp

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Falls account for almost two million emergency department visits per year in the U.S. and are the leading cause of injury deaths among adults 65 years of age and older. Despite efforts to reduce fall risk factors, about one-third of community-dwelling older adults fall each year in the U.S. New methods and devices are needed to prevent falls and to reduce morbidity and mortality related to falls. Presently, it is unknown if there is a measurable change in sway before a person falls. In order to find out, a wireless data acquisition system was developed as no existing tools were …

Elevated Temperature Oxidation Of Boron Modified Ti-6al-4v, Deborah May-Katherine Sweeney

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The addition of trace amounts (~0.1 wt%) of boron to titanium alloys refines theas-cast grain size by an order of magnitude from 2000μm to 200μm. The reduced grain size has potentially beneficial effects on the processibility of titanium alloys. Reports also indicate that the room temperature corrosion resistance of the boron containing alloys may be substantially greater than conventional titanium alloys. In this study, the effects of boron addition on oxidation resistance are investigated, since conventional titanium alloys have limited corrosion resistance in air above 650°C. The mass gain per unit surface area was measured during elevated temperatures exposed to …

Non-Linear Shunting Of Piezo-Actuators For Vibration Suppression, Anisetti Anusha

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Vibrations at a resonant frequency lead to catastrophic failure or at the very least, shorten the life span of the structure due to fatigue. These problems force engineers to implement damping techniques. Smart materials have been used over two decades to reduced vibration amplitudes. Recently, there has been much research and development on smart materials and structures.

This work introduces an innovative approach for vibration suppression using passively shunted piezolectric materials. Initially linear circuit elements such as resistors, capacitors, and inductances, or building a non-linear circuit with different impedance designs were used. Instead of such elements, a switched electromechanical shunt …

A Tabu Search Heuristic For Multi-Period Clustering To Rationalize Delivery Operations, Surya Sudha Khambhampati

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Delivery operations use centralized warehouses to serve geographically distributed customers. Resources (e.g. personnel, trucks, stock, and equipment) are scheduled from the warehouses to distributed locations with the aim of: (a) meeting customer demands and, (b) rationalizing delivery operation costs. My thesis investigates the problem of clustering customers based on their geographical vicinity and their multi-period demands, while optimally scheduling resources. The problem addresses with-and-without capacity constraints of vehicles at the warehouse. This problem is proven to be NP-Hard. Hence, solutions using state-of-the-art exact methods such as branch and bound are not pertinent due to the computation complexity involved. We develop …

Dynamic Pneumatic Muscle Actuator Control System For An Augmented Orthosis, Maria J. Gerschutz

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This dissertation develops, implements and analyzes a dynamic control system for a pneumatic muscle actuator (PMA) utilizing an augmented orthosis application. The application of PMAs are limited due to poor control capabilities resulting from dynamic nonlinearities. An adequate control system applying an appropriate dynamic pneumatic muscle actuator model increases the potential utility of PMAs in high-force applications including augmented orthotic applications.

The research conducts an initial analysis evaluating the feasibility of PMAs in high-force applications (force assistance with minimal displacement). A computational simulated control system (CSCS) is developed to analyze three different control schemes. The three PMA control schemes (position …

Study Of The Issues Of Computational Aerothermodynamics Using A Riemann Solver, Sean James Henderson

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This work is part of a project to more accurately model hypersonicflow. A number of issues in hypersonic flow are addressed.

The first issue addressed is that of air properties at increased temperatures. In particular the thermodynamic and transport properties of chemical equilibrium air are found for temperatures up to 30,000 K for a pressure range from 1x10-4 to 100 atm. This work provides properties at slightly higher temperatures for the lower pressure region than can be found in the literature. This work also covers adding equilibrium air chemistry to the computational fluid dynamics computer code known as AVUS.

The …

Simultaneous Rf/Eo Tracking And Characterization Of Dismounts, Jason M. Blackaby

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This thesis discusses the fusion of radar frequency(RF) data and electro-optical (EO) data for tracking and characterization of dismounts (i.e., humans). Each of these sensor modalities provides unique information about the location, structure, and movement of a dismount. The person's location is tracked on the 2D ground plane using RF data for range measurements and EO data for angle measurements. Using this information, measurements are made on the structure and dynamic motion (gait) of the person. An imaging approach is used to create spatio-temporal activity maps along with a three-dimensional reconstruction of the dismount.

Process Variation-Aware Timing Optimization With Load Balance Of Multiple Paths In Dynamic And Mixed-Static-Dynamic Cmos Logic, Kumar Yelamarthi

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The semiconductor technology has been advancing rapidly over the past decade to result in the design of several innovative applications. This advancement of technology with the shrinking device has allowed for placement of billions of transistor on a single microprocessor chip. On the other hand, this shrinking device sizes has presented the design engineers with two major challenges: timing optimization at multiple giga-hertz frequencies, and reducing the daunting effects of semiconductor process variations. Failure to account for these process variations often results in loss of design productivity by one generation, and might even result in design failure.

This research presents …

Intelligent Spectrum Sensor Radio, Omer Mian

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A cognitive radio is a radio with built-in intelligence that makes it able to utilize the radio frequency spectrum more efficiently by adapting to the changing conditions and frequency availability. In this thesis a spectrum sensor radio is designed that detects transmissions in FM band and determine the range of used and unused frequencies within the band. The radio then starts a transmission on a frequency among the available frequencies. This intelligent radio system design is implemented using the Universal Software Radio Peripheral and GNU Radio with a program written in python that uses a number of GNU Radio modules …

Composite Membranes For Proton Exchange Membrane Fuel Cells, Jinjun Shi

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Proton exchange membrane fuel cells (PEMFCs), often regarded as a green energy source, have become a promising candidate to replace traditional power sources. One of the obstacles toward commercialization of PEM fuel cells is lack of high performance and low cost proton exchange membranes. The objective of this study was to develop and evaluate higher-performance, Nafion-based composite proton exchange membranes that are suitable for operating at higher temperatures (> 85°C).

Proton exchange membranes were prepared by adding silica and heteropolyacids (HPAs) to a proton-conducting polymer matrix, Nafion. The added silica powder particles, either by direct mixing or sol-gel reaction, were …

System Design Of Undersea Vehicles With Multiple Sources Of Uncertainty, Todd W. Benanzer

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The work performed investigates the system design and optimization of an undersea vehicle. The system design is driven by the available components, the missions the vehicle is required to perform, and the performance the system configuration yields. The system design consists of three design modules: path planning, component selection and sizing, and structural analysis. The path planning module uses a novel application of the Particle Swarm Optimization algorithm named Path Planning by Additive Freedom. Additionally, the unknown aspects of the mission space through which the path propagates are dealt with using an uncertainty quantification method known as Evidence Theory. Component …

Algorithmic Techniques Employed In The Isolation Of Codon Usage Biases In Prokaryotic Genomes, Douglas W. Raiford Iii

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While genomic sequencing projects are an abundant source of information for biological studies ranging from the molecular to the ecological in scale, much of the information present may yet be hidden from casual analysis. One such information domain, trends in codon usage, can provide a wealth of information about an organism's genes and their expression. Degeneracy in the genetic code allows more than one triplet codon to code for the same amino acid, and usage of these codons is often biased such that one or more of these synonymous codons is preferred. Isolation of translational efficiency bias can have important …

Energy Efficient Image Video Sensor Networks, Paul Anthony Bender

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Image Video Sensor Networks are emerging applications for sensor network technologies. The relatively large size of the data collected by image video sensors presents new challenges for the sensor network in terms of energy consumption and channel capacity. We address each of these issues through the use of a high density network deployment utilizing some nodes as dedicated relay nodes.

A high density network allows network nodes to reduce their transmission power. This reduction in transmission power allows each node to conserve power and simultaneously increases the potential for spatially concurrent transmissions within the network, resulting in improved network throughputs. …

A Study Of Multi-Echelon Inventory Systems With Stochastic Capacity And Intermediate Product Demand, Suman Niranjan

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The research in this dissertation involves the study of several multi-echelon inventory systems with stochastic capacity and intermediate product demand. Specifically we analyze the behavior of the system which consists of several intermediate product demands. The analysis is primarily three fold i) developed update (relational) equations for all the multi-echelon inventory systems under several inventory allocation policies, ii) develop two simulation optimization approaches 1) OptQuest framework, and 2) IPA (Infinitesimal Perturbation Analysis) framework, used to minimize the total cost of the inventory systems that satisfy the desired customer service level, iii) obtain numerical results for all the multi-echelon inventory systems …

Evaluation Of Overlay/Underlay Waveform Via Sd-Smse Framework For Enhancing Spectrum Efficiency, Vasu D. Chakravarthy

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Recent studies have suggested that spectrum congestion is mainly due to the inefficient use of spectrum rather than its unavailability. Dynamic Spectrum Access (DSA) and Cognitive Radio (CR) are two terminologies which are used in the context of improved spectrum efficiency and usage. The DSA concept has been around for quite some time while the advent of CR has created a paradigm shift in wireless communications and instigated a change in FCC policy towards spectrum regulations. DSA can be broadly categorized as using a 1) Dynamic Exclusive Use Model, 2) Spectrum Commons or Open sharing model or 3) Hierarchical Access …

Transformation Of Object-Oriented Associations And Embedded References To Them, Sneha Swamy

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AFIT Wide Spectrum Object Modeling Environment (AWSOME) automatically generates executable code by applying transforms to the formal specifications developed from the domain knowledge. AWSOME uses the specification language called as AFIT Wide Spectrum Language (AWL). All the transforms developed for AWSOME depend on and manipulate Abstract Syntax Trees (ASTs) created by parsing the formal specifications of a model. The main idea is to speed the process of creating error free code, to aid reusability of code and also to make the maintenance changes to be consistent and correct. The AWSOME metamodel contains the structural (object) model, the functional (operations) model …

The Effect Of Dissolved Air On The Cooling Performance Of A Partially-Confined Fc-72 Spray, Rebekah Lee Puterbaugh

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The objective of this thesis is to investigate the heat transfer performance of a partially-confined FC-72 spray with varying dissolved air concentrations. An experimental test rig consisting of a spray chamber coupled to a fluid delivery loop system was used to obtain temperature, pressure, and critical heat flux (CHF) data. A downward facing nozzle within the spray chamber allowed the FC-72 fluid to be sprayed onto an upward facing, thick-film, resistor heater. The heater was mounted onto a glass post, with a sump system to allow removal of excess fluid. Type-E thermocouples were imbedded in the post to obtain temperature …

Design Of A Cmos Rf Front End Receiver In 0.18Μm Technology, Vishwas Kudur Sastry

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An RF front end receiver system refers to the analog down conversion stages of the wireless communication system. The Digital base-band signals cannot be transmitted directly through wireless channels due to the properties of electromagnetic waves. The baseband signals need to be converted to analog through a digital-to-analog converter (DAC), up converted to higher frequency using an up conversion mixer and then transmitted through the channel. The received signals are down converted to base band frequency and then converted to digital again using the analog to digital converter (ADC). The processes which the analog signal undergoes at the RF front …

Fpga Design Of A Hardware Efficient Pipelined Fft Processor, Ryan T. Bone

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Digital receivers involve fast Fourier transform (FFT) computations that require a large amount of arithmetic operations. The implementation of a FFT processor is one of the most challenging parts in the realization of a wideband receiver and its hardware complexity is very high. Hence, kernel function FFT processors have been proposed to meet real-time processing requirements and to reduce hardware complexity by rounding the kernel function to predetermined kernel points so as to eliminate the multipliers and use only shifters and adders or subtractors. Because of the nonlinear nature of this approximation by the rounding errors, spurious responses are generated …

Histogram-Based Template Matching Object Detection In Images With Varying Brightness And Contrast, Christina Da-Wann Schrider

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Our challenge was to develop a semi-automatic target detection algorithm to aid human operators in locating potential targets within images. In contrast to currently available methods, our approach is relatively insensitive to image brightness, image contrast and object orientation. Working on overlapping image blocks, we used a sliding difference method of histogram matching. Incrementally sliding the histograms of the known object template and the image region of interest (ROI) together, the sum of absolute histogram differences was calculated. The minimum of the resultant array was stored in the corresponding spatial position of a response surface matrix. Local minima of the …

Model And Solution Approaches For The Equipment Scheduling Under Disruption Problems In Usps Mail Processing And Distribution Centers, Arvindkumar Ravi Chakravarthy

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This research addresses the equipment scheduling problem under disruptions in United States Postal Service mail processing and distribution centers. These facilities contain a large variety of equipment and employ a non-homogeneous workforce that work on shifts of various lengths and start times. The scheduling of equipment (the determination of the configuration and usage of equipment to match mail arrivals) and the scheduling of workforce (the determination of the optimal size and composition of the workforce, their days off / lunch assignments, and overtime usage) to meet processing service commitment with a constantly changing demand are some of the most challenging …

A Stochastic Production Planning Model Under Uncertain Demand, Meenakshi Prajapati

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Production planning plays a vital role in the management of manufacturingfacilities. The problem is to determine the production loading plan consisting of the quantity of production and the workforce level - to fulfill a future demand. Although the deterministic version of the problem has been widely studied in the literature, the stochastic production planning problem has not. The application of production planning models could be limited if the stochastic nature of the problem, for example, uncertainty in future demand, is not addressed. This study addresses such a stochastic production planning problem under uncertain demand and its application in an enclosure …

Biomechanical Evaluation Of Locked And Non-Locked Constructs Under Axial And Torsion Loading, Vinit A. Patel

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Locking compression plates are proven to be safe for use in open reduction and internal fixation (ORIF). The ORIF is a procedure performed to treat fractures. It has various combination of holes, the system provides more options for clinicians to use either locking screw or non-locking screws. This thesis investigates and determines the best construct with special locking and non-locking screws under both axial and torsion loading. Twenty femur constructs were assembled with 2 cm osteotomy gap between femur shaft and condyle, bridged with 4.5 mm - 10 holes condyle plates. Femurs were divided in to 4 groups according to …

Dynamic Characterization Of A Pneumatic Muscle Actuator And Its Application To A Resistive Training Device, Jennifer L. Serres

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Research described in this dissertation expands the use of a biomechanical phenomenological model to a commercially available pneumatic muscle actuator (PMA). Due to the nonlinearities of the device, achieving accurate control is challenging. Experiments have been conducted that define boundaries of operation where linear approximations can be used to describe the dynamics of the PMA. Empirical data presented in this dissertation show that nonlinearities exist more prevalently at higher loads (on average >70% contractile force value). When the PMA is under high loads, low displacement occurs. Therefore, these regions are of less interest to design engineers. Once conditions of nonlinearities …

A Novel Accurate Approximation Method Of Lognormal Sum Random Variables, Xue Li

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Sums of lognormal random variables occur in many problems in wireless communications due to large-scale signal shadowing from multiple transmitters. With the emerging of cognitive radio technology, accurate analysis of interferences from multiple primary users and multiple secondary users is required. Such interferences are well modeled by the lognormal sum distribution. The lognormal sum distribution is known to have no close-form and is difficult to compute numerically. Several approximations to the lognormal sum distribution have been proposed and employed in literature. However, these approximation methods are not without their drawbacks. Some widely used approximation methods are not accurate at the …

Motion-Control System Of Bench-Top Ct Scanner, Tarpit Kaushikbhai Patel

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Computed Tomography (CT) imaging has found applications in many areas such as diagnostic visualization, quantitative estimation, and therapeutic verification. In this wide range of applications, a CT scanner that can provide the data collection schemes of both second- and third-generation data-collection geometries will be an asset for laboratory research. In this thesis project, we developed a mechanical design and constructed a dual-generation CT scanner that provides flexibility in accommodating a wide range of object sizes with minimum scan time. Using 3-D graphical design software, models of the current second-generation CT scanner and possible solutions for modification were simulated. Based on …

Finite Element Optimization Of Hip Implant Geometrical Parameters To Determine Safe Zones And Resist Dislocation, Himanshu K. Bhatt

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A computational study was performed using finite element analysis (FEA) of three dimensional solid hip implant models. Twelve different hip implant models were designed to investigate the performance of geometrical parameters affecting hip stability. The parameters examined were head diameter, neck diameter, head-to-neck ratio, neck angle and acetabular liner thickness. Component orientations included cup anatomical inclination and cup anteversion, which should be accounted for during total hip implant design as well as in the practice of arthroplasties. A static analysis was performed for all 12 hip designs using stainless steel 316L. von Mises stress, contact stress, contact penetration, and sliding …

Two Dimensional Localization Of Passive Uhf Rfid Tags, Bhavik Contractor

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The advent of GPS has redefined the need of a positioning system in today*#8217;s ubiquitous computing world. While GPS works satisfactorily and is quite a norm in an outdoor environment, it fails to work indoors due to the inherent complexity of an indoor environment. There is an ever increasing need to develop an indoor positioning system and a lot of research has been done to solve the problem of indoor localization. These solutions differ on the basis of cost, dependency on environment, line of sight requirements and so on.

Passive RFID (Radio Frequency Identification) tags pose an interesting solution to …

A Low-Cost Acoustic Array For Detecting And Tracking Multiple Acoustic Targets, Ellen E. Case

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A wide variety of real-world targets emit distinct acoustic signatures that not only distinguish them from one another but also provide spectral separation from background clutter. While acoustic signatures are distinct, they can also be highly variable, even for an individual target, making detection and tracking a challenging problem. This thesis presents a low-cost acoustic array using commercial off-the shelf (COTS) hardware to detect and track multiple small, moving, acoustic targets. It implements a cross-correlation method for calibration, delay-and-sum beamforming, CA-CFAR detection, a discrete Kalman filter for tracking, and nearest neighbor data association. In addition, the array is designed to …

An Algorithm For The Detection Of Handguns In Terahertz Images, Andrew J. Lingg

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This paper presents an algorithm for detecting handguns in terahertz images. Terahertz radiation is capable of penetrating certain materials which are opaque atoptical wavelengths, such as clothing, without the harmful effects of ionizing radiation. The approach taken is to segment objects of interest and classify them based on shape. We use a modified version of an active contour algorithm found in the open literature. Modifications include: a pre-processing step that includes clutter filtering and seeding of an initial contour; and a post-processing step that removes clutter pixels from the segmentation. The features used for classification are moment-based and Fourier shape …