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Articles 601 - 630 of 3445

Full-Text Articles in Engineering

Microstructural Characterization Of LensTm Ti-6al-4v: Investigating The Effects Of Process Variables Across Multiple Deposit Geometries, Laura Christine Davidson Jan 2018

Microstructural Characterization Of LensTm Ti-6al-4v: Investigating The Effects Of Process Variables Across Multiple Deposit Geometries, Laura Christine Davidson

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Laser based additive manufacturing of Ti-6Al-4V components is under consideration for aerospace applications. The mechanical properties of the finished components depend on their microstructure. Process mapping compares process variables such as heat source power, heat source travel speed, material feed rate, part preheat temperature and feature geometry to process outcomes such as microstructure, melt pool geometry and residual stresses. In this work, the microstructure of two-dimensional pads, multilayer pads, thin walls, and structural components at the steady state location was observed. A method for measuring β grain widths that allows for the calculation of standard deviations, confidence intervals, and variances …

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An Autonomous Intelligent Robotic Wheelchair To Assist People In Need: Standing-Up, Turning-Around And Sitting-Down, Iosif Papadakis Ktistakis Jan 2018

An Autonomous Intelligent Robotic Wheelchair To Assist People In Need: Standing-Up, Turning-Around And Sitting-Down, Iosif Papadakis Ktistakis

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The world’s ageing population has significantly increased over the last decades, which will result in one of the most significant transformations of the twenty-first century. As people age, they become more vulnerable to diseases and their health may need constant monitoring. At the same time, the number of people who have some kind of disability is also increasing. These people with disabilities may need daily assistance and monitoring of their health condition that is provided by specialists (health providers) at a high cost. A possible solution to the aforementioned problem comes from the assistive and intelligent robotics research area. The …

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Interactive Visualization Of Search Results Of Large Document Sets, James D. Anderson Jan 2018

Interactive Visualization Of Search Results Of Large Document Sets, James D. Anderson

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When presented with many search results, finding information or patterns within the data poses a challenge. This thesis presents the design, implementation and evaluation of a visualization enabling users to browse through voluminous information and comprehend the data. Implemented with the JavaScript library Data Driven Documents (D3), the visualization represents the search as clusters of similar documents grouped into bubbles with the contents depicted as word-clouds. Highly interactive features such as touch gestures and intuitive menu actions allow for expeditious exploration of the search results. Other features include drag-and-drop functionality for articles among bubbles, merging nodes, and refining the search …

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Switching Neural Network Systems For Nonlinear Tracking, Manoj Ghimire Jan 2018

Switching Neural Network Systems For Nonlinear Tracking, Manoj Ghimire

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In this thesis, we consider the problem of tracking in complex nonlinear dynamical systems. While the Kalman filter is known to be the mean-squared error optimal tracker under linear dynamics and linear measurements, more sophisticated models and algorithms are required for complex dynamics. Here, we consider switching systems where the dynamical properties vary (''switch modes") over time. For example, the dynamics of a vehicle may switch as it transitions from interstate to urban conditions, human speech dynamics switch as speakers change, and stock market dynamics switch with discrete news events. In this work, we use mode-dependent neural networks to capture …

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Overwhelming The Saa System Of Delivery Uavs By Drone Swarming, Barry Lynn Pfaff Jan 2018

Overwhelming The Saa System Of Delivery Uavs By Drone Swarming, Barry Lynn Pfaff

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As the Internet continues to replace the brick-and-mortar store as the main place for purchasing goods, web-based companies are looking for ways to reduce the cost of delivering those goods. The use of Unmanned Aerial Vehicles, or UAVs, is one delivery method that is increasingly being used. These UAVs can be programmed with delivery routes and destinations and can complete the job while requiring limited intervention from human controllers. Sense and Avoidance (SAA) systems have recently been incorporated into these UAVs so that they can detect objects in their flight path, reroute the UAV accordingly and operate even more autonomously. …

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Fully Transparent Computer Vision Framework For Ship Detection And Tracking In Satellite Imagery, Jason T. Gottweis Jan 2018

Fully Transparent Computer Vision Framework For Ship Detection And Tracking In Satellite Imagery, Jason T. Gottweis

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Tracking of ships in satellite imagery is a challenging problem in remote sensing since it requires both object detection and object recognition. Most of the resources available only cover one of these problems and are often filled with machine learning techniques which are costly to train. Additionally, the techniques covered in these resources are often difficult to replicate or may be hard to combine with other solutions to get a full tracking algorithm. The proposed framework offers a transparent and efficient alternative to machine learning approaches and includes preprocessing, detection, and recognition needed for tracking. All components of the framework …

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Augment The Multi-Modal Interaction Capabilities Of Hololens Through Networked Sensory Devices, Subhadra Tummalapally Jan 2018

Augment The Multi-Modal Interaction Capabilities Of Hololens Through Networked Sensory Devices, Subhadra Tummalapally

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Augmented Reality (AR) places virtual contents along with real objects to enhance user perception in the physical environment. It is a technology that has shown great potential in many industries such as medicine, education and transportation. AR devices, such as Microsoft HoloLens, come with multi-modal interaction capabilities, such as voice, gesture and gaze, to support intuitive and reliable human-computer interactions. However, HoloLens gesture support is limited to simple gestures like tap, bloom and hold, it stops short to support meaningful interaction through full hand gesture and motion tracking, which may be critical in field operations of various industry practices in …

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Wideband Doa And Parameter Estimation Of Chirp Sources Using Dcft And Compressive Sensing, Luay A. Al Irkhis Jan 2018

Wideband Doa And Parameter Estimation Of Chirp Sources Using Dcft And Compressive Sensing, Luay A. Al Irkhis

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Direction of Arrival (DoA) estimation of chirp sources has many applications in radar, sonar and medical imaging. This work considers DoA and parameter estimation of wide- band chirp sources by the use of Discrete Chirp Fourier Transform (DCFT), its Compres- sive Sensing formulation (CS-DCFT) and Distributed CS. DCFT is similar to traditional Discrete Fourier Transform (DFT) but with chirp ba- sis and two-dimensional search over chirp rate and chirp frequency. For chirp parame- ters estimation, the proposed Compressive Sensing (CS) formulation uses the parametric DCFT basis to achieve superior estimator performance in polynomial time using Orthog- onal Matching Pursuit (OMP) …

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Impact Of Noise Level On Task Performance And Workload And Correlation To Personality, Kaylee Marie Eakins Jan 2018

Impact Of Noise Level On Task Performance And Workload And Correlation To Personality, Kaylee Marie Eakins

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An ideal work environment supports a culture of high performance, low mental workload, and quick turnarounds. The impact of noise on three types of tasks in a lab work environment were examined while attempting to identify correlations between a subject's personality and their tolerance to noise. Neuroticism, agreeableness, conscientiousness, and extroversion correlated significantly with subjective (NASA-TLX) and physiological mental workload measures (heart rate variability and eye-tracking). The results show that task type impacts the performance, task duration, and mental workload. Although the physiological workload measures showed significant impact, the parameters standard deviation of R-R intervals and LF/HF ratio agreed with …

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A Twitter-Based Study For Understanding Public Reaction On Zika Virus, Roopteja Muppalla Jan 2018

A Twitter-Based Study For Understanding Public Reaction On Zika Virus, Roopteja Muppalla

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In recent times, social media platforms like Twitter have become more popular and people have become more interactive and responsive than before. People often react to every news in real-time and within no-time, the information spreads rapidly. Even with viral diseases like Zika, people tend to share their opinions and concerns on social media. This can be leveraged by the health officials to track the disease in real-time thereby reducing the time lag due to traditional surveys. A faster and accurate detection of the disease can allow health officials to understand people's opinion of the disease and take necessary precautions …

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A Model For Seasonal Dynamic Networks, Jace D. Robinson Jan 2018

A Model For Seasonal Dynamic Networks, Jace D. Robinson

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Sociotechnological and geospatial processes exhibit time varying structure that make insight discovery challenging. This paper presents statistical model of systems with seasonal dynamics, modeled as a dynamic network, to address this challenge. It assumes the probability of edge formations depend on a type assigned to incident nodes and the current time. Time dependencies are modeled by unique seasonal processes. The model is studied on several synthetic and real datasets. Superior fidelity of this model on seasonal datasets compared to existing network models, while being able to remain equally accurate for networks with randomly changing structure, is shown. The model is …

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A Simulation Method For Studying Effects Of Site-Specific Clutter On Sar-Gmti Performance, Marcus James Campbell Jan 2018

A Simulation Method For Studying Effects Of Site-Specific Clutter On Sar-Gmti Performance, Marcus James Campbell

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Synthetic aperture radar (SAR) is an invaluable tool for detection of ground moving targets when combined with processing techniques of ground moving target indication (GMTI). This work investigates a simulation methodology for studying impact of site-specific ground clutter on SAR-GMTI performance. A terrain model is proposed and is based on digital terrain elevation data (DTED) and national land-use land-cover data (NLCD) as provided by the US Geological Survey. The proposed physical optics simulation method capitalizes on high-fidelity digital target models in combination with the proposed terrain model. SAR phase history is generated for a moving commercial target in situ of …

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Multiscale Modeling Of Hemodynamics In Human Vessel Network And Its Applications In Cerebral Aneurysms, Hongtao Yu Jan 2018

Multiscale Modeling Of Hemodynamics In Human Vessel Network And Its Applications In Cerebral Aneurysms, Hongtao Yu

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Three-dimensional (3D) simulation of patient-specific morphological models has been widely used to provide the hemodynamic information of individual patients, such as wall shear stress (WSS), oscillatory shear index (OSI), and flow patterns, etc. Since patient-specific morphological segment was only restricted locally, boundary conditions (BCs) are required to implement the CFD simulation. Direct measurements of the flow and pressure waveforms were often required as input BCs for 3D CFD simulations of patient-specific models. However, as the morphology develops, the feedback from this topological deformation may lead to BCs being altered, and hence without this feedback, the flow characteristics of the morphology …

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Virtual Doctor: An Intelligent Human-Computer Dialogue System For Quick Response To People In Need, Stavros Mallios Jan 2018

Virtual Doctor: An Intelligent Human-Computer Dialogue System For Quick Response To People In Need, Stavros Mallios

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One of the challenges of our society is the existence of chronic-related conditions and diseases among the elderly and people at risk. Apart from the welfare of people, a significant impact of this phenomenon is the accumulation of high financial costs for both individuals and health care systems. In order to address this issue and to reduce its effects, many efforts have been made towards preventing, identifying in early stages and, generally, managing chronic-related medical conditions and diseases. As a result, there has been a keen research and market interest in health monitoring devices during the past few decades. Nevertheless, …

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Demonstrating The Functionality And Efficacy Of Blockchain-Based System In Healthcare Using Simulation Tools, Jad S. Mubaslat Jan 2018

Demonstrating The Functionality And Efficacy Of Blockchain-Based System In Healthcare Using Simulation Tools, Jad S. Mubaslat

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Blockchain and cryptocurrencies have been a rapidly growing industry and area of academic research since Bitcoin's launch in early 2009. Blockchains have already been applied in spaces outside of finance, such as healthcare. This work explores the Bitcoin blockchain and a blockchain-based care coordination system through the use of modeling and simulation tools. Two agent based models are constructed: one to represent the Bitcoin blockchain, and a second to represent a blockchain-based care coordination system, MDChain. Insight is provided that is relevant to current issues within the Bitcoin community and predictions are made as to its future. The feasibility of …

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A Multi-Formal Languages Collaborative Scheme For Complex Human Activity Recognition And Behavioral Patterns Extraction, Anargyros Angeleas Jan 2018

A Multi-Formal Languages Collaborative Scheme For Complex Human Activity Recognition And Behavioral Patterns Extraction, Anargyros Angeleas

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Human Activity Recognition is an actively researched domain for the past few decades, and is one of the most eminent applications of today. It is already part of our life, but due to high level of uncertainty and challenges of human detection, we have only application specific solutions. Thus, the problem being very demanding and still remains unsolved. Within this PhD we delve into the problem, and approach it from a variety of viewpoints. At start, we present and evaluate different architectures and frameworks for activity recognition. Henceforward, the focal point of our attention is automatic human activity recognition. We …

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Fabrication And Characterizations Of Lagp/Peo Composite Electrolytes For All Solid-State Lithium-Ion Batteries, Jeremy J. Lee Jan 2018

Fabrication And Characterizations Of Lagp/Peo Composite Electrolytes For All Solid-State Lithium-Ion Batteries, Jeremy J. Lee

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With the rise of electric vehicles and increasing dependence on mobile electronics, the demands for lithium-ion batteries have followed in tandem for their high energy and power densities. However, traditional lithium-ion batteries consisting of liquid electrolytes have limited operating temperatures and are susceptible to ignition and subsequent fires. Recently, battery research has diverged into solid state chemistry to address the aforementioned issues. In this research, we systematically investigate a series of ceramic/polymer lithium-ion conducting composite electrolytes, i.e. Li1.4Al0.4Ge1.6(PO4)3 /lithiated polyethylene oxide (LAGP/PEO). Lithiated PEO was prepared with two different lithium salts, LiBF4 and LITFSI. The impacts of the LAGP on …

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Use Of Adaptive Mobile Applications To Improve Mindfulness, Wiehan Boshoff Jan 2018

Use Of Adaptive Mobile Applications To Improve Mindfulness, Wiehan Boshoff

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Mindfulness is the state of retaining awareness of what is happening at the current point in time. It has been used in multiple forms to reduce stress, anxiety, and even depression. Promoting Mindfulness can be done in various ways, but current research shows a trend towards preferential usage of breathing exercises over other methods to reach a mindful state. Studies have showcased that breathing can be used as a tool to promote brain control, specifically in the auditory cortex region. Research pertaining to disorders such as Tinnitus, the phantom awareness of sound, could potentially benefit from using these brain control …

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Domain-Specific Knowledge Extraction From The Web Of Data, Sarasi Lalithsena Jan 2018

Domain-Specific Knowledge Extraction From The Web Of Data, Sarasi Lalithsena

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Domain knowledge plays a significant role in powering a number of intelligent applications such as entity recommendation, question answering, data analytics, and knowledge discovery. Recent advances in Artificial Intelligence and Semantic Web communities have contributed to the representation and creation of this domain knowledge in a machine-readable form. This has resulted in a large collection of structured datasets on the Web which is commonly referred to as the Web of data. The Web of data continues to grow rapidly since its inception, which poses a number of challenges in developing intelligent applications that can benefit from its use. Majority of …

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Sensor Data Streams Correlation Platform For Asthma Management, Vaikunth Sridharan Jan 2018

Sensor Data Streams Correlation Platform For Asthma Management, Vaikunth Sridharan

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Asthma is a high-burden chronic inflammatory disease with prevalence in children with twice the rate compared to adults. It can be improved by continuously monitoring patients and their environment using the Internet of Things (IoT) based devices. These sensor data streams so obtained are essential to comprehend multiple factors triggering asthma symptoms. In order to support physicians in exploring causal associations and finding actionable insights, a visualization system with a scalable cloud infrastructure that can process multimodal sensor data and Patient Generated Health Data (PGHD) is necessary. In this thesis, we describe a cloud-based asthma management and visualization platform that …

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A Novel Approach For Cancer Characterization Using Latent Dirichlet Allocation And Disease-Specific Genomic Analysis, Hima Bindu Yalamanchili Jan 2018

A Novel Approach For Cancer Characterization Using Latent Dirichlet Allocation And Disease-Specific Genomic Analysis, Hima Bindu Yalamanchili

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Two challenging problems in the clinical study of cancer are the characterization of cancer subtypes and the classification of individual patients according to those subtypes. Further, understanding the role of differential gene expression in the development of and molecular response to cancer is a complex problem that remains challenging, in part due to the sheer number of genes and gene products involved. Traditional statistical approaches addressing these problems are hindered by within-class heterogeneity and challenges inherent in data integration across high-dimensional data. In addition, many current machine learning methods do not lend themselves to biological interpretation. We have developed a …

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Development And Thermal Management Of A Dynamically Efficient, Transient High Energy Pulse System Model, Nathaniel J. Butt Jan 2018

Development And Thermal Management Of A Dynamically Efficient, Transient High Energy Pulse System Model, Nathaniel J. Butt

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As technology advances, the abilities of civilian and military vehicles, both air and ground, will undoubtedly increase as well. One of the main areas of improvement is in the electronics area. The new electronics are ever smaller, use ever higher amounts of electrical power, and require ever smaller temperature tolerances. This leads to the problem of effectively managing the increasing thermal loads and temperature tolerances on these systems. One electronic system that causes concern is a high energy pulse system (HEPS). These devices have very high thermal loads (100s of kW). On an air vehicle, where thermal management by legacy …

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Measuring Goal Similarity Using Concept, Context And Task Features, Vahid Eyorokon Jan 2018

Measuring Goal Similarity Using Concept, Context And Task Features, Vahid Eyorokon

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Goals can be described as the user's desired state of the agent and the world and are satisfied when the agent and the world are altered in such a way that the present state matches the desired state. For physical agents, they must act in the world to alter it in a series of individual atomic actions. Traditionally, agents use planning to create a chain of actions each of which altering the current world state and yielding a new one until the final action yields the desired goal state. Once this goal state has been achieved, the goal is said …

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Image Stitching And Matching Tool In The Automated Iterative Reverse Engineer (Aire) Integrated Circuit Analysis Suite, David C. Bowman Jan 2018

Image Stitching And Matching Tool In The Automated Iterative Reverse Engineer (Aire) Integrated Circuit Analysis Suite, David C. Bowman

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Due to current market forces, leading-edge semiconductor fabrication plants have moved outside of the US. While this is not a problem at first glance, when it comes to security-sensitive applications, over-production, device cloning, or design alteration becomes a possibility. Since these vulnerabilities exist during the fabrication phase, a Reverse Engineering (RE) step must be introduced to help ensure secure device operation. This thesis proposes several unique methods and a collection of tools to ensure trust assurance in integrated circuit design by detecting fabrication flaws and possible hardware Trojans using several image processing techniques; fused into a singular view of the …

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A Robust Low Power Static Random Access Memory Cell Design, A. V. Rama Raju Pusapati Jan 2018

A Robust Low Power Static Random Access Memory Cell Design, A. V. Rama Raju Pusapati

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Stability of a Static Random Access Memory (SRAM) cell is an important factor when considering an SRAM cell for any application. The Static Noise Margin (SNM) of a cell, which determines the stability, varies under different operating conditions. Based on the performance of three existing SRAM cell designs, 6T, 8T and 10T, a 10 Transistor SRAM cell is proposed which has good stability and has the advantage of reduced read power when compared to 6T and 8T SRAM cells. The proposed 10T SRAM cell has a single-ended read circuit which improves SNM over the 6T cell. The proposed 10T cell …

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Defect Engineering: Novel Strengthening Mechanism For Low- Dimensional Zinc Oxide Nanostructures, Seyed Emad Rezaei Jan 2018

Defect Engineering: Novel Strengthening Mechanism For Low- Dimensional Zinc Oxide Nanostructures, Seyed Emad Rezaei

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The advent of nanomaterials has opened a new avenue for designing and fabricating materials with unique properties, e.g., superior mechanical properties. Based on a common notion, the perfect structures are assumed to exhibit better mechanical properties, such as higher yield strength and Young's modulus. Therefore, researchers have devoted an extensive amount of time to decrease defect concentration by fabricating materials with the micro/nanoscale, e.g., nanowires (NWs) and nanobelts (NBs), to enhance the mechanical characteristics of the system. However, defects are a part of the fabrication process and precise control over synthesizing procedure is needed to eliminate them from the material. …

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Impact Of Near-Field-To-Far-Field Transformation On Sar Images Formed In An Indoor Non-Anechoic Environment, Jacob D. Compaleo Jan 2018

Impact Of Near-Field-To-Far-Field Transformation On Sar Images Formed In An Indoor Non-Anechoic Environment, Jacob D. Compaleo

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This work investigates the impact of the near-field-to-far-field transformation (NFFFT) algorithm on phase history measurement collections completed in the Sensors and Signals Exploitation Laboratory (SSEL). SSEL is an indoor non-anechoic environ- ment that is at risk to some measurement interferences such as multiple bounces. Complete 360-degree phase history measurements of scale model aircraft are con- ducted at varying range values within the near-field limit. These measurements are calibrated with the Mie series scattering solution for a sphere. After calibration, the measurements are transformed using the NFFFT, with radar cross-section (RCS) estimated. RCS of the transformed data is compared with the …

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M1 To M2 Macrophage Induction Using Retinoic Acid And Mesenchymal Stem Cells Loaded On An Electrospun Pullulan/Gelatin Scaffold To Promote Healing Of Chronic Wounds, Kaivon Assani Jan 2018

M1 To M2 Macrophage Induction Using Retinoic Acid And Mesenchymal Stem Cells Loaded On An Electrospun Pullulan/Gelatin Scaffold To Promote Healing Of Chronic Wounds, Kaivon Assani

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Modulation of macrophage polarization is required for effective tissue repair and regenerative therapies. Conversion of macrophages from inflammatory M1 to fibrotic M2 phenotype could help in diseases such as chronic wound which are stuck in inflammatory state. During the inflammatory phase, macrophages are of the inflammatory phenotype (M1) and distribute pro-inflammatory cytokines including TNF-a and IL1[beta] which are microbicidal and recruit/activate cells. In normal wound healing macrophages then switch to a fibrotic phenotype (M2) promoting wound closure by angiogenesis, and matrix deposition. Chronic wounds are a major biological and financial burden to both patients and the health care system, costing …

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Effect Of Dimensionality On In Vitro Growth Environment And Mesenchymal Stem Cell Function, Fatema Tuj Zohora Jan 2018

Effect Of Dimensionality On In Vitro Growth Environment And Mesenchymal Stem Cell Function, Fatema Tuj Zohora

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The use of the standard two dimensional (2D) cell culture has laid down the fundamentals of molecular and cell biology. However, recent advances in cell-based regenerative medicine raises the concern on deconstructing cellular behaviors in more physiologically relevant three dimensional (3D) microenvironments. Differences in cell response in 2D versus 3D systems arise from the perturbations in gene expression patterns that stem from how cells sense their underlying 2D or surrounding 3D matrices and adjust their phenotypes accordingly. Thus, cells are no longer considered as a solitary entity of genome but a context arises from a combinatorial interactions of cell-ECM, cell-cell, …

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Functionalization And Characterization Of Chemical Vapor Deposited Graphene Sheets Towards Application In Chemical Vapor Sensing, Nicholas Alexander Engel Jan 2018

Functionalization And Characterization Of Chemical Vapor Deposited Graphene Sheets Towards Application In Chemical Vapor Sensing, Nicholas Alexander Engel

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Chemical/biological sensors serve many purposes in protecting machinery, the environment, and human life/wellness. Graphene, a two-dimensional (2-D) material made up of carbon atoms in a honeycomb-like lattice, is promising for applications to chemical/biological sensing due to its unique properties. Functionalization of graphene by surface decorating with nanoparticles and increasing interior adsorption sites can tailor its catalytic activity and electrical properties, and hence, important for detecting and distinguishing trace hazardous gases. This research introduces two different approaches to functionalize graphene towards enhanced sensitivity and selectivity of graphene-based sensors. The morphologies, structures, and electrical properties of the functionalized graphene are systematically characterized. …

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