Engineering Commons^™

A Framework To Support Spatial, Temporal And Thematic Analytics Over Semantic Web Data, Matthew Steven Perry

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Spatial and temporal data are critical components in many applications. This is especially true in analytical applications ranging from scientific discovery to national security and criminal investigation. The analytical process often requires uncovering and analyzing complex thematic relationships between disparate people, places and events. Fundamentally new query operators based on the graph structure of Semantic Web data models, such as semantic associations, are proving useful for this purpose. However, these analysis mechanisms are primarily intended for thematic relationships. This dissertation proposes a framework built around the RDF data model for analysis of thematic, spatial and temporal relationships between named entities. …

Effect Of A Graded Layer On The Plastic Dissipation During Mixed-Mode Fatigue Crack Growth On Plastically Mismatched Interfaces, Craig M. Baudendistel

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Recent work has proposed a dissipated energy theory of fatigue crack growth in layered materials under mixed-mode loading. An inherent assumption of this prior work is that a perfect crack exists along the interface joining the top and bottom layers. The current work extends the approach of previous studies to incorporate a grading of plastic properties between the two layers through parametric finite element modeling with ABAQUS. An elastic-plastic 2D model using 8-node biquadratic elements was used to map the plastic dissipation of a two layer specimen with a grading of plastic properties parallel to the crack face. This property …

Global Optimization Of An Aircraft Thermal Management System Through Use Of A Genetic Algorithm, Christopher T. Allen

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Optimization algorithms utilize known information about the system to identify solutions that are more efficient and meet the requirements of the user. The algorithms require an objective function, or formula (linear or nonlinear) that models what the user is looking to optimize, in order to begin the search for a more feasible solution. Because optimization problems can involve either linearor non-linear functions, various algorithms have been created that can locate optimum solutions faster depending on the type of objective function being optimized.

This research focuses on optimizing an aircrafts thermal management system by using one such algorithm. This was performed …

Study Of Multi-Modal And Non-Gaussian Probability Density Functions In Target Tracking With Applications To Dim Target Tracking, Peter V. Hlinomaz

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The majority of deployed target tracking systems use some variant of the Kalman filter for their state estimation algorithm. In order for a Kalman filter to be optimal, the measurement and state equations must be linear and the process and measurement noises must be Gaussian random variables (or vectors). One problem arises when the state or measurement function becomes a multi-modal Gaussian mixture. This typically occurs with the interactive multiple model (IMM) technique and its derivatives and also with probabilistic and joint probabilistic data association (PDA/JPDA) algorithms. Another common problem in target tracking is that the target's signal-to-noise ratio (SNR) …

Real-Time Hilbert Transform And Autocorrelation For Digital Wideband Communication Applications, Murthy, Dilip Srinivasa

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Digital wideband receiver plays a key role in communication and radar systems, and it is used detect and analyze wide range of radio frequency (RF) signals. A digital Instantaneous Frequency Measurement (IFM) receiver is designed, where implementation of a real-time architecture of a Hilbert transform and autocorrelation algorithm is presented. Real-time architecture performs continuous monitoring and processing of the incoming signal. Prior to the previous one bit design, the input data fed to the Hilbert transform is 8-bit wide at a clock rate of 320 MHz with the input data rate is increased by a factor of eight, an 8-bit …

The Influence Of Thickness On The Complex Modulus Of Air Plasma Sprayed Ceramic Blend Coatings, Jason Edgar Hansel

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Previous research suggests that damping of metallic beams that have a hard ceramic coating applied on them is proportional to the coating thickness. This indicates that the damping is a volume dependent material property. Since thickness variations are likely in an actual application, it is essential to understand the role that coating thickness plays in damping effectiveness. For this research, a series of tests were conducted using substrate beams of 90 mil Ti-6Al-4V, coated with 3 mils of an air plasma sprayed NiCrAlY bond coat followed by a Titania-Alumina ceramic blend coating applied via air plasma spray in one of …

Modeling Training Effects On Task Performance Using A Human Performance Taxonomy, Douglas P. Meador

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There is little argument that modern military systems are very complex, both in terms of the resources in time and money to develop them and the infrastructure that is required to produce trained operators. To properly execute human systems integration during the acquisition process, systems built to train operators must be developed that optimize training. Consequently, the training system community would benefit from simulation models that provide the ability to make accurate predictions of training processes, and allow the decision maker to specify an optimum combination of operator performance after training and the cost of that training. The goal of …

The Effect Of Variable Gravity On The Cooling Performance Of A 16-Nozzle Spray Array, Levi J. Elston

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The objective of this thesis was to investigate the cooling performance of a 16-nozzle spray array, using FC-72 as the working fluid, in variable gravity conditions with additional emphasis on fluid management and flow stability. A flight test experiment was modified to accommodate a 16-nozzle spray array, which was then tested in the parabolic flight trajectory environment of NASA's C-9 reduced gravity aircraft. The 16-nozzle array was designed to cool a 25.4 x 25.4 [mm] area on a thick film resistive heater used to simulate electronic components. Data was taken and reduced as a result of flight tests conducted over …

Implementation Of Simulation For Network Service Delivery Point Capacity Analysis, Tiffany Jill Harper

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As businesses consolidate and modernize their operations, the impact on their network and computing infrastructure is a major consideration. In this thesis, discrete event simulation is used to show how implementation of an Enterprise Resource Planning (ERP) system can impact network performance and ultimately affect end-users. More specifically, the model simulates the flow of data packets across a network, through a Service Delivery Point (SDP), which is comprised of routers, switches, and firewalls that connect a Local Area Network to a Wide Area Network.

The model was used to run to determine the affect of more network traffic and additional …

Integrated Inductors, Mandar Dilip Kavimandan

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Integrated inductors, also called spiral inductors, on-chip inductors, or planarinductors, are inseparable part in radio frequency integrated circuits (RFICs). Increasing growth in RFICs from the past few decades has forced study of these components in greater detail. Apart from IC inductors, there are several components mounted on a chip - namely capacitors, resistors, MOSFETs, diodes etc. It is extremely important to understand the electrical and magnetic behavior of all these components. Electrical behavior of these components is easy to understand. However, the real challenge lies in realizing and predicting the magnetic behavior of components, namely, inductors and capacitors. Capacitors have …

Influence Of Voltage Source Pulse Width Modulated Switching And Induction Motor Circuit On Harmonic Current Content, Martin T. Lange

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The purpose of this research is to present analysis of the harmonic content present in the phase current of a three phase induction motor while being powered by a voltage source pulse-width modulated (PWM) variable speed drive (VSD). First, the topology and circuit of the drive, its operational fundamentals and waveform appearance are presented and discussed. Next, the three-phase induction motor circuit model and operational characteristics are discussed. Finally, the harmonic content present in the induction motor phase current is determined by use of the PSPICE model. The ability of the PSICE simulation to determine harmonic content is established. It …

Microstructural Stability And Thermomechanical Processing Of Boron Modified Beta Titanium Alloys, Balakrishna Cherukuri

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One of the main objectives during primary processing of titanium alloys is to reduce the prior beta grain size. Producing an ingot with smaller prior beta grain size could potentially eliminate some primary processing steps and thus reduce processing cost. Trace additions of boron have been shown to decrease the as-cast grain size in alpha + beta titanium alloys. The primary focus of this dissertation is to investigate the effect of boron on microstructural stability and thermomechanical processing in beta titanium alloys.

Two metastable beta titanium alloys: Ti-15Mo-2.6Nb-3Al-0.2Si (Beta21S) and Ti-5Al-5V-5Mo-3Cr (Ti5553) with 0.1 wt% B and without boron additions …

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 …