Engineering Commons^™

A Guided Neighborhood Search Applied To The Split Delivery Vehicle Routing Problem, Rafael E. Aleman

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The classic vehicle routing problem considers the distribution of goods to geographically scattered customers from a central depot using a homogeneous fleet of vehicles with finite capacity. Each customer has a known demand and can be visited by exactly one vehicle. Each vehicle services the assigned customers in such a way that all customers are fully supplied and the total service does not exceed the vehicle capacity. In the split delivery vehicle routing problem, a customer can be visited by more than one vehicle, i.e., a customer demand can be split between various vehicles. Allowing split deliveries has been proven …

An Integrated Simulation Environment Combining Process-Driven And Event-Driven Models, Vishnu Sharma Kesaraju

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A simulation framework that integrates process-driven and event-driven approaches offers a powerful combination of tools to the modeler. In process-driven simulation models, the system can be represented by block diagrams or system networks through which entities flow to mimic real life system objects. In event-driven models, the system can be represented by event graphs, which focus on the abstraction of the event rather than on observable physical entities. In this research, a simulation environment is proposed that integrates both the approaches, i.e. process and event. One of the main outcomes of working in such an environment is that modelers can …

Determining The Effect Of Speaker's Gender And Speech Synthesis On Callsign Acquisition Test (Cat) Results, Jasminkumar B. Soni

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Effective and efficient speech communication is one of the leading factors for success of battlefield operation. With the increases in the levels of gender diversity in military services, it is important to assess the effectiveness of voice for both genders in communication systems. The purpose of this research study was to determine the effect of the speaker's voice (male and female) on the speech intelligibility (SI) performance of the Callsign Acquisition Test (CAT). In addition, the effects of synthesized speech were evaluated. The CAT test is a new SI test that has been developed for military use. A group of …

Aircraft Thermal Management Using Loop Heat Pipes, Andrew J. Fleming

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The objective of this thesis was to determine the feasibility of using loop heat pipes to dissipate waste heat from power electronics to the skin of a fighter aircraft and examine the performance characteristics of a titanium-water loop heat pipe under stationary and elevated acceleration fields. In the past, it has been found that the boundary condition at the condenser can be a controlling factor in the overall performance of this type of thermal management scheme. Therefore, the heat transfer removed from the aircraft skin has been determined by modeling the wing as a flat plate at zero-incidence as a …

Low Cost Lightweight Mode Forming System For Angle Of Arrival Estimation, Mark Anthony Stewart

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Current mode forming systems have high angular resolution and operate over large bandwidths. System size, complexity, and cost restrict the use of these systems to ground-based or large-airframe platforms. A spiral antenna in conjunction with mission- specific modularized planar microstrip mode formers would allow for angle of arrival estimations on smaller platforms such as a medium-sized UAV. This thesis investigates the mode forming characteristics of a planar four arm spiral antenna driven with a planar microstrip mode former designed to operate over a single personal communications band. The theoretical foundation for a closed-form angle of arrival estimation given by Penno …

Trusted Querying Over Wireless Sensor Networks And Network Security Visualization, Giovani Rimon Abuaitah

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Wireless sensor networks (WSNs) as an emerging technology faces numerous challenges. Sensor nodes are usually resource constrained. Sensor nodes are also vulnerable to physical attacks or node compromises. Answering queries over data is one of the basic functionalities of WSNs. Both resource constraints and security issues make designing mechanisms for data aggregation particularly challenging. In this thesis, we first explore the various security techniques for data aggregation in WSNs then we design and demonstrate the feasibility of an innovative reputation-based framework rooted in rigorous statistical theory and belief theory to characterize the trustworthiness of individual nodes and data queries in …

Tyflos: A Wearable Navigation Prototype For Blind & Visually Impaired; Design, Modelling And Experimental Results, Dimitrios Dakopoulos

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The need for assistive devices has, had and will have a large merit in many engineering research arenas. This dissertation deals with the design, modeling, implementation and experimentation of the navigation component of a wearable assistive system for blind and visually impaired people, called TYFLOS (ΤΥΦΛΟΣ) which is the Greek word for "Blind".

The current prototype consists of two mini cameras attached to a pair of conventional eye-glasses, a 2D tactile display vibration array) which consists of 16 vibrating elements arranged in a 4x4 manner, attached to an elastic vest worn on the user's abdomen, a portable computer, an ear-speaker …

A Predictive Model Of Cognitive Performance Under Acceleration Stress, Richard Andrew Mckinley

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Extreme acceleration maneuvers encountered in modern agile fighter aircraft can wreak havoc on human physiology thereby significantly influencing cognitive task performance. Increased acceleration causes a shift in local arterial blood pressure and profusion causing declines in regional cerebral oxygen saturation. As oxygen content continues to decline, activity of high order cortical tissue reduces to ensure sufficient metabolic resources are available for critical life-sustaining autonomic functions. Consequently, cognitive abilities reliant on these affected areas suffer significant performance degradations. This goal of this effort was to develop and validate a model capable of predicting human cognitive performance under acceleration stress. An Air …

Detection Of Small Aircraft Using An Acoustic Array, Anne M. Zelnio

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Detection of small aircraft visually or with radar sensors is difficult due to its small size, low-velocity, and low radar cross section. This effort investigates the detection and localization of small aircraft using an acoustic array. The acoustic array was fabricated using low-cost commercial off-the shelf (COTS) hardware that is mobile and can adapt to different signatures and deployment environments. A cross-correlation method for calibration and delay-and-sum beamforming was performed. A generalized likelihood ratio test (GLRT)-based energy detector and a GLRT-based sinusoidal signal detector was applied after beamforming. Detection was also performed using various subpace adaptive beamforming techniques including MUSIC, …

Cellular Function Of The Ia-Motoneuron Circuit Following Peripheral Nerve Regeneration, Katie Leigh Bullinger

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Successful regeneration of a severed peripheral nerve is insufficient to restore the stretch reflex. This deficit occurs despite successful muscle reinnervation and functional restoration of the circuit components. For example, Ia afferents encode muscle stretch, Ia-motoneuron synapses reform to the extent of restoring low frequency transmission, and activation of motoneurons results in muscle force output. However, when recording intracellularly from reinnervated rat motoneurons during ramp hold and release muscle stretch, no excitatory synaptic potentials are detected in 2/3 motoneurons (Haftel et al., 2005), a clear sign that the synapses connecting Ia afferents with motoneurons are physiologically disrupted. This thesis examines …

High Voltage Dc Converter Systems Modeling, Simulation And Analysis, Manish A. Dalal

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The thesis provides insights into important modeling techniques to model the converter system, machine design, control and power stages and integration of the various sub systems to simulate the system level performance. This innovative modeling and simulation project is very relevant to optimizing the system performance, designing the sub circuits, components selection, predicting the system stability and impulse responses. The thesis presents modeling and simulation of three different 270VDC converter systems and comparing their performances against each other. The 270VDC converter system accepts either Generator 3-phase AC voltages or fixed three voltage source followed by single or dual converter stages …

Fuzzy Logic Control Of A Switched-Inductor Pwm Dc-Dc Buck Converter In Ccm, Terry Kolakowski

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Modern electronics are operating at lower voltages with higher currents, requiring power converters to deliver these requirements efficiently. In this thesis, a switch-inductor buck converter is designed for the required specifications; and for the selected design, component losses and efficiency are calculated. A MATLAB/Simulink model is constructed, and tested in the presence of load and source disturbances to show the converter cannot maintain the desired output voltage when the disturbances are applied.

A fuzzy logic PID controller is designed to regulate the duty cycle of the converter to control the output voltage. Control surfaces are designed for proportional, integral, and …

Dual Mode Scramjet: A Computational Investigation On Combustor Design And Operation, Ryan Timothy Milligan

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Numerical analysis was performed on a Dual-Mode Scramjet isolator-combustor. Preliminary analysis was performed to form a baseline geometry. Another study validated the results of a 2D model compared to a 3D model. Stable combustion was shown at two different flight conditions, M=3.0 and M=2.5. A marginal 5% decrease in stream thrust was shown by introducing a 50/50 mix of methane and ethylene. Based on the results of the preliminary analysis, detailed geometry analysis was performed on the 3D baseline geometry. Adding a new set of cavity feeding injectors increased the overall stream thrust and the equivalence ratio in the cavity. …

Ion Transport Mechanisms During Hyposmotic Regulatory And Isosmotic Apoptotic Volume Decreases In A Human Lens Epithelial Cells Line, Ameet Ajit Chimote

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Living cells maintain constant volume in response to physiological stresses by altering trans-membrane ion, solute and water flow. In the present study, early and late membrane transport changes in human lens epithelial (HLE-B3) cells under hyposmotic and apoptotic stress were compared. Cell potassium (Ki), rubidium (Rbi)-uptake and water content were measured by atomic absorption spectrophotometry and gravimetry, respectively. Intracellular chloride concentration [Cl]i was determined with the fluorescence dye N- (ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE), during regulatory volume decrease (RVD) after hyposmotic stress and apoptotic volume decrease (AVD) induced by staurosporine (STP), a protein-kinase inhibitor. Cell water increased in hyposmotic balanced salt solution …

Conductance Modulation In Bilayer Graphene Nanoribbons, Kirti Kant Paulla

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Graphene nanoribbons are among the recently discovered carbon nanostructures, with unique characteristics for novel applications. One of the most important features of graphene nanoribbons, from both basic science and application points of view, is their electrical conductivity. In this research, we study the electrical conductance of single and double layer nanoribbons of specified widths and edge geometries. The calculations are carried out using ab initio quantum mechanical simulations for obtaining the optimized atomic configurations of the nanoribbons and their electronic structures. These results are then used to calculate the conductance characteristics via Green's function approach to the Landauer's formalism. We …

Layered Sensing Using Master-Slave Cameras, Donald Rodney Mclemore Jr.

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The objective of this thesis is to demonstrate the layered sensing concept using Master-Slave cameras. The process of 2D camera calibration and several key factors that can present error during such calibration are described. The analysis and results are based on calibration of a pinhole model camera system. The calibration is accomplished using OpenCV software and the results are analyzed using MATLAB software. These results are divided into intrinsic and extrinsic camera parameters. These parameters are then used to determine the position and orientation of the object in the camera coordinate system. This thesis also explores the use of two …

New Formic Acid Fuel Cell Orientations To Reduce The Cost Of Cell Components, John Calvin Holtkamp

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Formic acid fuel cells show the potential of outperforming or replacing direct methanol fuel cells. A number of issues need to be overcome in order for fuel cells, specifically formic acid fuel cells, to be seriously considered for use in small electronic devices. One of the largest issues inhibiting the commercial success of fuel cells is the cost of the components. The catalyst and ion-conducting membrane, key components in a fuel cell, are both expensive. With the current amount of costly materials needed to construct a fuel cell, fuel cells will have limited success in becoming mainstream power sources in …

Novel Intelligent Power Supply Using A Modified Pulse Width Modulator, Gary Richard Doss Jr.

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The objective of this M.S. Thesis was to design, simulate, construct and test a pulse-width-modulated Buck DC-DC Converter and its compensated feedback system. Equations for the design and component selection of a buck converter have been obtained for operating the buck converter in the continuous conduction mode (CCM). A hardware version of the converter design has been implemented to demonstrate the functionality of the designed converter. Also, a digital buck converter control system has been designed and simulated. This digital buck converter led to the development of a proposed control scheme for Switched Mode Power Supplies (SMPS).

A novel hybrid …

The In Vitro Interactions Between Tubulin And Hiv-1 Rev Require Rev's Multimerization And Arginine-Rich Motifs, Amit Sharma

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Rev is a 13 kDa regulatory HIV protein essential for viral replication. It trans-activates expression of late viral proteins by multimerizing onto target mRNA and promoting their export into the cytoplasm. During attempts to find the solution conditions needed to study Rev structure, Watts et al. (2000) discovered that Rev depolymerizes microtubules (MTs) in vitro through the formation of ringed tubulin intermediates called Rev-tubulin toroids (RTTs). Rev interactions with MTs are specific and are thought to mimic the mechanism of Kinesin-13 proteins, themselves potent MT depolymerases that regulate the assembly of the mitotic spindle. If Rev and Kinesin-13 proteins share …

Piezoresistive Feedback Control Of A Mems Thermal Actuator, Robert K. Messenger, Quentin Theodore Aten, Timothy W. Mclain, Larry L. Howell

Faculty Publications

Feedback control of MEMS devices has the potential to significantly improve device performance and reliability. One of the main obstacles to its broader use is the small number of on-chip sensing options available to MEMS designers. A method of using integrated piezoresistive sensing is proposed and demonstrated as another option. Integrated piezoresistive sensing utilizes the inherent piezoresistive property of polycrystalline silicon from which many MEMS devices are fabricated. As compliant MEMS structure’s flex to perform their functions, their resistance changes. That resistance change can be used to transduce the structures’ deflection into an electrical signal. The piezoresistive microdisplacement transducer (PMT) …

A Sequential Bayesian Approach For Hydrologic Model Selection And Prediction, Kuo-Lin Hsu, Hamid Moradkhani, Soroosh Sorooshian

Civil and Environmental Engineering Faculty Publications and Presentations

When a single model is used for hydrologic prediction, it must be capable of estimating system behavior accurately at all times. Multiple-model approaches integrate several model behaviors and, when effective, they can provide better estimates than that of any single model alone. This paper discusses a sequential model fusion strategy that uses the Bayes rule. This approach calculates each model's transient posterior distribution at each time when a new observation is available and merges all model estimates on the basis of each model's posterior probability. This paper demonstrates the feasibility of this approach through case studies that fuse three hydrologic …

Feedback Between Residual Circulations And Sediment Distribution In Highly Turbid Estuaries: An Analytical Model, Stefan A. Talke, Huib E. De Swart, H. M. Schuttelaars

Civil and Environmental Engineering Faculty Publications and Presentations

Motivated by field studies of the Ems estuary which show longitudinal gradients in bottom sediment concentration as high as O(0.01 kg/m⁴), we develop an analytical model for estuarine residual circulation based on currents from salinity gradients, turbidity gradients, and freshwater discharge. Salinity is assumed to be vertically well mixed, while the vertical concentration profile is assumed to result from a balance between a constant settling velocity and turbulent diffusive flux. Width and depth of the model estuary are held constant. Model results show that turbidity gradients enhance tidally averaged circulation upstream of the estuarine turbidity maximum (ETM), …

An Idealized Model And Systematic Process Study Of Oxygen Depletion In Highly Turbid Estuaries, Stefan A. Talke, Huib E. De Swart, Victor De Jonge

Civil and Environmental Engineering Faculty Publications and Presentations

The sensitivity of oxygen depletion in turbid estuaries to parameters like freshwater discharge, depth, and sediment availability is investigated using an idealized model. The model describes tidally averaged circulation and suspended sediment concentration (SSC), which are input into an advection–diffusion sink module of dissolved oxygen (DO). Based on the analysis of field data collected in the Ems estuary, the modeled oxygen depletion rates are proportional to SSC. The model is calibrated to the observed variation of DO with SSC and temperature. Modeled DO closely tracks changes to the estuarine turbidity zone (ETZ): increased channel depth, decreased freshwater discharge, and decreased …

Using The Taguchi Design And The Central Composite Design To Increase The Robustness Of A Process From Its Raw Material Variability, Alvaro Cuevas

Open Access Theses & Dissertations

This research presents an experimental study where four controllable and one noise factor are analyzed using the Taguchi approach and the Central Composite Design (CCD) in order to induce robustness in a process that is being designed to treat residual grease from small restaurants. Three response variables are analyzed separately to establish the parameters conditions to obtain the most robust process output. These suggested conditions are validated conducting confirmation runs that are compared statistically to the predictions from the Taguchi prediction model for the Taguchi approach, and the Response optimizer for the CCD. The accuracy of each method is measured …

Assessment Of Super-Resolution For Face Recognition From Very-Low Resoution Images, James Roger Roeder

Open Access Theses & Dissertations

Super-Resolution (SR) involves the registration of multiple images/frames and reconstruction of a single higher resolution image. The goal of this research is to use multiple, very-low resolution images, such as those produced from a video sequence in a wireless sensor network system, as input to the super-resolution process in a face recognition system. The algorithm used for face recognition is the Fisherfaces method with a nearest neighbor classifier used for the recognition decision. Super-resolution consists of two stages, a registration stage and a reconstruction stage.

The testing images were segmented using a simple skin color detection approach. After the cropping, …

Characterization Of High Resolution Range And Doppler Chaotic Ladar, Berenice Verdin

Open Access Theses & Dissertations

Compared to high range resolution radar systems, chaotic LADAR (laser detection and ranging) has the potential of providing an increase in range-Doppler resolution by several orders of magnitude.

The purpose of this project is to determine system parameters and signal processing schemes required to build a high resolution chaotic LADAR. Specifically, the LADAR is based on a semiconductor laser that generates a wideband chaotic signal via optical feedback. The behavior of the laser output is modeled by changing the control parameters of the delay differential equations that dictate the behavior of the laser output. Depending on the feedback level and …

Análisis Del Sistema Actual De Abastecimiento De Bogotá. Agua Subterránea Como Fuente Alterna O De Contingencia, Claudia Natalia López Martínez, Gerlin Andrea Polo Campos

Ingeniería Civil

No abstract provided.

High Temperature Oxidation Characteristics Of Nb-10w-Xcr Alloys, Maria Del Pilar Moricca

Open Access Theses & Dissertations

The use of refractory metals in high temperature applications has been attractive for several years. Systems based on niobium represent a potential new generation of refractory materials systems because of their low density, high melting points, and strength at elevated temperatures. Despite these desirable characteristics, the widespread use of niobium-based alloys is limited because its oxidation resistance is still inadequate for structural applications. Understanding the oxidation kinetics of Nb-based alloys and the role of the different phases in the oxidation process is of crucial importance to improve the oxidation resistance of these materials.

The effect of Cr content on the …

Impacting Testing Of High Temperature Ceramics Through The Use Of A Vitiated Heater For Hot And Cold Fire Collisions, Adrian Trejo

Open Access Theses & Dissertations

Material testing is a crucial step during the design process as particular materials serve as safety and life saving conditions. In this study, a MoSi2 is chosen as the target specimen to undergo impact under high temperatures. An impact apparatus is designed and constructed for the purpose of propelling alumina particles at high velocities. A nozzle using compressed nitrogen gas is used to fire the particle at the desired velocities. Due to the possibility of thermal shock occurring at higher temperatures, a separate nozzle utilizing vitiation heating is designed to fire the particle at equally higher temperatures to prove the …

Preserving Assets In At-Risk Municipalities: Financial Strategies For Climate Change Adaptation, New England Environmental Finance Center

Climate Change

A large share of America's population, businesses and economic activity now occurs in coastal areas. At the same time, during this century many coastal communities are likely to be severely impacted by sea level rise and increased storm surge and tidal flooding.

“What to do” about this vulnerability is the subject of this brief. It is intended to help municipalities identify courses of action and steps they might take toward increasing their resilience, especially regarding financial resources that will need to be allocated toward the various strategies identified.