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Articles 72121 - 72150 of 196596

Full-Text Articles in Engineering

Analytical And Experimental Investigation Of Time-Variant Acceleration Fields, Justin A. Williams Jan 2019

Analytical And Experimental Investigation Of Time-Variant Acceleration Fields, Justin A. Williams

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Devices expected to operate in elevated or non-standard acceleration fields are often tested in similar conditions prior to deployment. Typically these tests only simulate steady-state acceleration fields in one direction. However, real acceleration fields often vary both directionally and temporally. Designing experiments to produce these conditions requires careful forethought and analysis in order to understand the emergent acceleration components that result from the methodology. An experiment was designed and executed on a horizontal centrifuge in which the radial acceleration varied sinusoidally between -10 < a_r < 10 g. Negative acceleration was achieved by rotating the test article relative to the radial acceleration vector using a servo motor. A model was developed that predicted the acceleration field at every point along the test article. The model provided important information such as the acceleration magnitude and direction anywhere on the test device at any point in time. This model was then used to optimize the velocity profile of the servo motor to minimize experimental artifacts.

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Adaptive Identification Of Classification Decision Boundary Of Turbine Blade Mode Shape Under Geometric Uncertainty, Ian M. Boyd Jan 2019

Adaptive Identification Of Classification Decision Boundary Of Turbine Blade Mode Shape Under Geometric Uncertainty, Ian M. Boyd

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Integrally Bladed Rotors (IBR) of aircraft turbine engines suffer from fluctuations in the dynamic response that occurs due to blade to blade geometric deviations. The Stochastic Approach for Blade and Rotor Emulation (SABRE) framework has been used to enable a probabilistic study of mistuned blades in which a reduced order modeling technique is applied in conjunction with sets of surrogate models, called emulators, to make predictions of mistuned mode shapes. SABRE has proven useful for non-switching mode shapes. However, switching mode shapes have non-stationary or discontinuous response surfaces which reduce the accuracy of the surrogate models used in SABRE. To …

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Kbot: Knowledge-Enabled Personalized Chatbot For Self-Management Of Asthma In Pediatric Population, Dipesh Kadariya Jan 2019

Kbot: Knowledge-Enabled Personalized Chatbot For Self-Management Of Asthma In Pediatric Population, Dipesh Kadariya

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Asthma, chronic pulmonary disease, is one of the major health issues in the United States. Given its chronic nature, the demand for continuous monitoring of patient’s adherence to the medication care plan, assessment of their environment triggers, and management of asthma control level can be challenging in traditional clinical settings and taxing on clinical professionals. A shift from a reactive to a proactive asthma care can improve health outcomes and reduce expenses. On the technology spectrum, smart conversational systems and Internet-of-Things (IoTs) are rapidly gaining popularity in the healthcare industry. By leveraging such technological prevalence, it is feasible to design …

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Conditional Dilated Attention Tracking Model - C-Datm, Tyler Clayton Highlander Jan 2019

Conditional Dilated Attention Tracking Model - C-Datm, Tyler Clayton Highlander

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Current commercial tracking systems do not process images fast enough to perform target-tracking in real- time. State-of-the-art methods use entire scenes to locate objects frame-by-frame and are commonly computationally expensive because they use image convolutions. Alternatively, attention mechanisms track more efficiently by mimicking human optical cognitive interaction to only process small portions of an image. Thus, in this work we use an attention-based approach to create a model called C-DATM (Conditional Dilated Attention tracking Model) that learns to compare target features in a sequence of image-frames using dilated convolutions. The C-DATM is tested using the Modified National Institute of Standards …

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Leveraging Schema Information For Improved Knowledge Graph Navigation, Rama Someswar Chittella Jan 2019

Leveraging Schema Information For Improved Knowledge Graph Navigation, Rama Someswar Chittella

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Over the years, the semantic web has emerged as a new generation of the world wide web featuring advanced technologies and research contributions. It has revolutionized the usage of information by allowing users to capture and publish machine-understandable data and expedite methods such as ontologies to perform the same. These ontologies help in the formal representation of a specified domain and foster comprehensive machine understanding. Although, the engineering of ontologies and usage of logic have been an integral part of the web semantics, new areas of research such as the semantic web search, linking and usage of open data on …

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Deposition Of Nanoparticles Or Thin Films Via Magnetron Sputtering Towards Graphene Surface Functionalization And Device Fabrication, Bridget Jul Larson Jan 2019

Deposition Of Nanoparticles Or Thin Films Via Magnetron Sputtering Towards Graphene Surface Functionalization And Device Fabrication, Bridget Jul Larson

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Graphene, a 2-dimensional single layer of carbon, has high carrier mobility, strength and electrical conductivity. Due to the absence of a band gap and chemical reactivity, pristine graphene has less competitiveness in semiconductors and sensors. Functionalizing graphene is imperative in the development of advanced applications. Among various wet chemical or physical vapor deposition, magnetron sputtering is cost-effective, minimum maintenance, user-friendly, and can be used to rapidly deposit nano-particulates or thin films with less contaminations on any substrates surface. This study is to investigate the morphology evolution of the deposited films using magnetron sputtering and to find appropriate conditions for nanoparticulate …

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Static Evaluation Of Type Inference And Propagation On Global Variables With Varying Context, Ivan Frasure Jan 2019

Static Evaluation Of Type Inference And Propagation On Global Variables With Varying Context, Ivan Frasure

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Software reverse engineering (SRE) is a broad field with motivations ranging from verifying or documenting gordian source code files to understanding and reimplementing binary object files and executables. SRE of binaries is exceptionally compelling and challenging due to large amounts of information that can be lost in the compilation progress. A central area in SRE is type inference. Type inference is built around a fundamental step in understanding the behavior of a binary, recovering the types of data in the program. Type inference has many unique techniques in both static and dynamic type inference systems that have been implemented in …

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Using Cfd To Improve Off-Design Throughflow Analysis, Troy J. Lanchman Jan 2019

Using Cfd To Improve Off-Design Throughflow Analysis, Troy J. Lanchman

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In turbomachinery design, complex internal flows give rise to significant losses and blockage whose effects are difficult to properly analyze without detailed computational fluid dynamics (CFD) methods or experiments. In a typical design method, CFD is used in conjunction with simpler throughflow or cascade codes to hasten the process. However, the lesser physical accuracy of the design codes demands the inclusion of models to improve the accuracy of the throughflow codes. This thesis aims to use CFD data to generate improved loss and blockage models for a 2D compressor throughflow code by matching throughflow data to CFD data using optimizations. …

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The Development Of The Human-Automation Behavioral Interaction Task (Habit) Analysis Framework, Isabelle Catherine Baird Jan 2019

The Development Of The Human-Automation Behavioral Interaction Task (Habit) Analysis Framework, Isabelle Catherine Baird

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Complex systems involve the collaboration of automated agents and goal-oriented human operators in a dynamic environment, and dynamic environments required dynamic automation. The implementation of automation fundamentally changes the nature of the cognitive demands by means of changing the role of the human operator. The augmentation of operator situation awareness has become a major design objective in the development of human-automated systems. Extensive literature identified the out-of-the-loop performance problem as a human-automation interaction challenge. This thesis presents the Human-Automation Behavioral Interaction Task (HABIT) Analysis, as a novel approach to assessing human-automation interaction challenges, such as out-of-the-loop consequences. The novel framework …

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Anticipation In Dynamic Environments: Deciding What To Monitor, Zohreh A. Dannenhauer Jan 2019

Anticipation In Dynamic Environments: Deciding What To Monitor, Zohreh A. Dannenhauer

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In dynamic environments, external changes may occur that may affect planning decisions and goal choices. We claim that an intelligent agent should actively watch for what can go wrong and anticipate changes in the environment that allows the changing of its plan or changing of a given goal. In this thesis, we focus on the relationship between perception, act, interpretation, and planning. We claim that these components are not independent and need to interact with each other to help the agent succeed in achieving its goals and plans. If newly encountered world information affects the plan, the agent adapts to …

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Agent-Based Simulation Of Artificial-Intelligence-Assisted Transfer Of Care, Paul B. Stone Jan 2019

Agent-Based Simulation Of Artificial-Intelligence-Assisted Transfer Of Care, Paul B. Stone

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This study demonstrates the application of Agent-Based Simulation as a potential training aid for Transfer of Care (ToC) between EMS and a hospital triage department. The specific aim was to develop a simulation to increase the efficiency and accountability of information communication during ToC to test the suitability of Agent-Based Simulation to address training requirements in complex, health provision settings. This paper focuses on the design of the training simulation, including the development of individual agents within the simulation through the user interface elements and the evaluation and verification of the prototype simulator. The primary objective is for the simulation …

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Digital Instantaneous Frequency Measurement Receiver For Fine Frequency And High Sensitivity, Bilal Khudhur Abdulhammed Abdulhamed Jan 2019

Digital Instantaneous Frequency Measurement Receiver For Fine Frequency And High Sensitivity, Bilal Khudhur Abdulhammed Abdulhamed

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Wideband technology has been applied to many wide bandwidth applications when there is a need to send much different information in a short time from one point and received from another point in high precision and accuracy. A wideband receiver reports a signal without tuning if the signal is within the input bandwidth. The analog Instantaneous Frequency Measurement (IFM) receiver has been used for decades to cover a very wide input bandwidth and report one accurate frequency on a short pulse at a time. The digital IFM use a high sampling rate ADC to operate in a wide bandwidth, Hilbert …

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Type 2 Diabetes Leads To Impairment Of Cognitive Flexibility And Disruption Of Excitable Axonal Domains In The Brain, Leonid M. Yermakov Jan 2019

Type 2 Diabetes Leads To Impairment Of Cognitive Flexibility And Disruption Of Excitable Axonal Domains In The Brain, Leonid M. Yermakov

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Type 2 diabetes is a metabolic disease affecting millions of people around the world. Cognitive and mood impairments are among its many debilitating complications, but disease mechanism(s) remain elusive. Here, we present a series of behavioral tasks that demonstrate impairment of cognitive flexibility in db/db mice, a commonly used type 2 diabetes model. Using immunohistochemistry, we demonstrate disruption of axon initial segments (AIS) and nodes of Ranvier, excitable axonal domains regulating neuronal output, in brain regions associated with cognitive and mood impairments. Finally, we present results of exercise treatment that ameliorates AIS disruption in these animals. Establishing cognitive flexibility deficits …

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Software Implementations And Applications Of Elliptic Curve Cryptography, Kirill Kultinov Jan 2019

Software Implementations And Applications Of Elliptic Curve Cryptography, Kirill Kultinov

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Elliptic Curve Cryptography (ECC) is a public-key cryptography system. Elliptic Curve Cryptography (ECC) can achieve the same level of security as the public-key cryptography system, RSA, with a much smaller key size. It is a promising public key cryptography system with regard to time efficiency and resource utilization. This thesis focuses on the software implementations of ECC over finite field GF(p) with two distinct implementations of the Big Integer classes using character arrays, and bit sets in C++ programming language. Our implementation works on the ECC curves of the form y^2 = x^3 + ax + b (mod p). The …

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Rules With Right Hand Existential Or Disjunction With Rowltab, Sri Jitendra Satpathy Jan 2019

Rules With Right Hand Existential Or Disjunction With Rowltab, Sri Jitendra Satpathy

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One hotly debated research topic is, “What is the best approach for modeling ontologies?”. In the earlier stages of modeling ontologies, researchers have favored the usage of description logic to capture knowledge. One such choice is the Web Ontology Language (OWL) that is based on description logic. Many tools were designed around this principle and are still widely being used to model and explore ontologies. However, not all users find description logic to be intuitive, at least not without an extensive background in formal logics. Due to this, researchers have tried to explore other ways that will enable such users …

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Computational Simulation Of A Femoral Nail Fracture, Stephen Charles Whatley Jan 2019

Computational Simulation Of A Femoral Nail Fracture, Stephen Charles Whatley

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Every year in the United States roughly 300,000 people over the age of 65 suffer from a hip fracture. Ninety five percent of which are the result from a fall. The resulting hip fracture can be classified into several categories of fracture. Depending on the damage the patient could be implanted with a femoral nail device to assist in their recovery. These devices can, however, have complications during recovery. In some cases, these nails can have a failure rate as high as 10%. When failure occurs, extensive investigations are needed to determine the causes of failure. These investigations involve physical …

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A Model To Optimize Major Trauma Network Considering Patient Safety, Monit D. Vaishnav Jan 2019

A Model To Optimize Major Trauma Network Considering Patient Safety, Monit D. Vaishnav

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Trauma is any physical injury that has the potential to cause prolonged disability and death if the appropriate level of care is not administered in a timely fashion. Existing approaches in the literature and by the American College of Surgeons (ACS) to optimize the network of trauma centers are limiting. To address this challenge, we introduce the Trauma Network Design Problem, a bi-objective mathematical model that aims at determining the optimal trauma network by minimizing the weighted sum of mistriages. We use the trauma network data from 2012 for the state of Ohio to illustrate the use of our approach …

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Development Of A Computer Program For Transient Heat Transfer Coefficient Studies, Sri Prithvi Samrat Samayamantula Jan 2019

Development Of A Computer Program For Transient Heat Transfer Coefficient Studies, Sri Prithvi Samrat Samayamantula

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At the present time, the magnitude of transient convective heat transfer is approximated using heat transfer coefficient correlations developed for steady state conditions. This is done by necessity, as transient heat transfer correlations are not readily available. There is a rare transient heat transfer correlation found in the literature, but the number of correlations available can be counted on one hand. In addition, the literature does provide some plots of Nusselt numbers for specific cases of transient convective heat transfer, but these are limited to the specific case for which they were developed. The work presented in this thesis is …

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As-Manufactured Modeling Of A Mistuned Turbine Engine Compressor Evaluated Against Experimental Approaches, Daniel L. Gillaugh Jan 2019

As-Manufactured Modeling Of A Mistuned Turbine Engine Compressor Evaluated Against Experimental Approaches, Daniel L. Gillaugh

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As-manufactured rotors behave quite differently than nominal, as-designed rotors due to small geometric and material property deviations in the rotor, referred to as mistuning. Traditional integrally bladed rotor (IBR) modeling approaches assume each blade is identical. State-of-the-art IBR dynamic response predictions can be accomplished using asmanufactured models (AMM) generated via optical topography measurements and mesh morphing. As-manufactured models account for geometric deviations occurring through the machining process, material deviations and field wear, allowing each blade to respond differently. Rotor designs are intended to avoid resonance crossings throughout an engine’s operating range, but total avoidance is challenging. This has led to …

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Recognition Of Incomplete Objects Based On Synthesis Of Views Using A Geometric Based Local-Global Graphs, Michael Christopher Robbeloth Jan 2019

Recognition Of Incomplete Objects Based On Synthesis Of Views Using A Geometric Based Local-Global Graphs, Michael Christopher Robbeloth

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The recognition of single objects is an old research field with many techniques and robust results. The probabilistic recognition of incomplete objects, however, remains an active field with challenging issues associated to shadows, illumination and other visual characteristics. With object incompleteness, we mean missing parts of a known object and not low-resolution images of that object. The employment of various single machine-learning methodologies for accurate classification of the incomplete objects did not provide a robust answer to the challenging problem. In this dissertation, we present a suite of high-level, model-based computer vision techniques encompassing both geometric and machine learning approaches …

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Processing And Properties Of Multifunctional Two-Dimensional Nanocomposite Based On Single Wall Carbon Nanotubes, Ali M. Al Mafarage Jan 2019

Processing And Properties Of Multifunctional Two-Dimensional Nanocomposite Based On Single Wall Carbon Nanotubes, Ali M. Al Mafarage

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Truly single layer (monolayer) films of unmodified zigzag single-walled carbon nanotubes by using the Langmuir-Blodgett (LB) technique have been processed successfully. Measurements of their mechanical and optoelectric properties were achieved. Different theoretical equations were used based on the results obtained from the experimental part to study the properties and structures of the produced material and their composite. The produced films were highly oriented as determined by polarized Raman spectroscopy and as shown by scanning tunneling microscopy (STM). The films have a significant amount of flexibility which makes their behavior similar to rubbery materials. They can also be deposited on different …

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System Identification And Model-Based Control Of Quadcopter Uavs, Andrew P. Szabo Jan 2019

System Identification And Model-Based Control Of Quadcopter Uavs, Andrew P. Szabo

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As control systems become more sophisticated, more accurate system models are needed for control law design and simulation. In this research, a nonlinear dynamic model of a quadcopter UAV is presented and model parameters are estimated off-line using in-flight experimental data. In addition, a model-based classical control law for the quadcopter UAV is designed, simulated, and then deployed in UAV flight tests. The intent of this research is to identify a model which may be simple enough to easily use for control law design, and accurate enough for simulation. In addition, a model-based classical control law is designed to for …

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Knowledge Graph Reasoning Over Unseen Rdf Data, Bhargavacharan Reddy Kaithi Jan 2019

Knowledge Graph Reasoning Over Unseen Rdf Data, Bhargavacharan Reddy Kaithi

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In recent years, the research in deep learning and knowledge engineering has made a wide impact on the data and knowledge representations. The research in knowledge engineering has frequently focused on modeling the high level human cognitive abilities, such as reasoning, making inferences, and validation. Semantic Web Technologies and Deep Learning have an interest in creating intelligent artifacts. Deep learning is a set of machine learning algorithms that attempt to model data representations through many layers of non-linear transformations. Deep learning is in- creasingly employed to analyze various knowledge representations mentioned in Semantic Web and provides better results for Semantic …

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Exploring Two-Dimensional Graphene And Silicene In Digital And Rf Applications, Zhonghang Ji Jan 2019

Exploring Two-Dimensional Graphene And Silicene In Digital And Rf Applications, Zhonghang Ji

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Since the discovery of graphene, two-dimensional (2D) materials have attracted intensive interests in the past 15 years and there has been a growing interest in exploring new materials beyond graphene, such as silicene, germanene, etc. Numerous papers have been published to demonstrate their extraordinary electronic, optical, biological, and thermal properties which render broad applications in various fields. However, the absence of band gap in graphene and silicene prohibits their uses in digital applications. This dissertation reviews recent progress on band gap opening based on mono- and bi- layer silicene and presents a new silicon atomic structure which exhibits a 0.17 …

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A Graphene/Rf Gas Sensor, Kathleen Louise Brockdorf Jan 2019

A Graphene/Rf Gas Sensor, Kathleen Louise Brockdorf

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Toxic chemicals have been used as chemical warfare agents since ancient times, but World War 1 saw the beginning of modern chemical proliferation. There are many methods of detecting these agents, but the combination of high sensitivity, specificity, fast response, and small form factor is difficult to achieve. More recently, graphene has been identified as a possible sensing material for ammonia and other substances. This research documents a novel method of using graphene as a chemical sensor, utilizing a radio-frequency approach to sensing. This approach utilizes all available information from the material, such as permittivity and conductivity, instead of simply …

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Non-Deterministic Metamodeling For Multidisciplinary Design Optimization Of Aircraft Systems Under Uncertainty, Daniel L. Clark Jr. Jan 2019

Non-Deterministic Metamodeling For Multidisciplinary Design Optimization Of Aircraft Systems Under Uncertainty, Daniel L. Clark Jr.

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To make coupled multi-physics-informed design decisions, multidisciplinary analysis, design optimization and uncertainty quantification must be present to accurately represent the full system under investigation. Unfortunately, all of these processes are computationally demanding, requiring a large number of system evaluations with identified uncertain variables, and iterative system evaluations with respect to the design variables of interest. Surrogate or metamodels are used to alleviate the computational burden in both these design exploration activities by trading accuracy with efficiency. The primary objective of this dissertation is to develop a flexible surrogate modeling technique capable of quantifying the uncertainty of multidisciplinary systems in an …

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Preparation And Characterization Of Porous Pdms For Printed Electronics, Eyad Khalid M. Balbaid Jan 2019

Preparation And Characterization Of Porous Pdms For Printed Electronics, Eyad Khalid M. Balbaid

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Fabricating an elastomeric substrate with internal features could provide a novel structure with distinctive mechanical properties that allow them to stretch, bend and absorb the impact force. To date, polydimethylsiloxane (PDMS) is a great candidate as a substrate for flexible electronic applications, due to easy fabrication, high stability and low cost. In the current thesis, porous PDMS samples are fabricated and characterized based on the particle size and the fusion of salt and sugar treated micro-regions. The liquid PDMS is prepared by mixing the silicon elastomer base (Sylgard 184) and elastomer curing agent using volume ration 10:1. The salt and …

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Simulation, Experimentation, Control And Management Of A Novel Fuel Thermal System, Austin L. Tipton Jan 2019

Simulation, Experimentation, Control And Management Of A Novel Fuel Thermal System, Austin L. Tipton

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Modern aircraft experience increasing thermal loads from electronics, electromechanical actuators, and directed energy weapons. These aircraft also have a reduced ability to transfer thermal energy to the atmosphere due to the use of composite skins and a limited number of air intake ports. For aircraft that use fuel as a heatsink, these factors can cause the fuel at points of the system to exceed temperature limits, which can result in fuel coking, damage to subsystems, and even complete system failure. This thesis investigates the fuel thermal management shortcomings of contemporary aircraft systems and suggests a new methodology to extend performance. …

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Tapped-Inductor Buck Dc-Dc Converter, Ankit Chadha Jan 2019

Tapped-Inductor Buck Dc-Dc Converter, Ankit Chadha

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There is a high demand for low step-down dc voltage conversions. Many conventional power converters that are currently being used have a moderate conversion ratio and this may not be sufficient to meet the demand. This can be achieved by either cascading power converters or using converters with a low step-down conversion ratio. Cascading the converters increases the power conversion stage complexity and increase the order of the system, while also affecting the stability. Using converters with a high conversion ratio seems to be a more intelligent option to root. This dissertation tackles to analyze one such converter, called tapped-inductor …

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Chondroitin Sulfate Hydrogels For Total Wound Care Devices, Tushar Goswami Jan 2019

Chondroitin Sulfate Hydrogels For Total Wound Care Devices, Tushar Goswami

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Chondroitin sulfate (CS) is a naturally occurring bio-polymer found in areas of high cartilage in mammals. In directed applications, such as hydrogels, CS can be used to impact keratinocyte growth cycles. In this work, CS based hydrogels were utilized to accelerate wound healing and, in conjunction with a graphene sensor, monitor wound fluid pH. The hydrogels were cast onto a graphene field effect transistor (GFET) to obtain the benefits of the hydrogel wound healing capabilities, while also utilizing the pH sensitivity of the graphene. Results showed that the hydrogel caused a fivefold increase in cell size over the course of …

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