Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

University of Texas at Arlington

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 1081 - 1110 of 3180

Full-Text Articles in Engineering

Improved Initialization For The Multi Layer Perceptron, Abhishek Vinay Mainkar May 2018

Improved Initialization For The Multi Layer Perceptron, Abhishek Vinay Mainkar

Electrical Engineering Theses - Archive

A Multilayer Perceptron (MLP) neural network is used for solving nonlinear functional problems like function approximation, classification, data processing etc. MLP neural networks are usually trained using back propagation, which is a non-convex optimization problem for most of the loss functions. As there are multiple local minima, non-convex optimization curves generally converge to different optimal points for different initial conditions. So it not only affects the speed of the convergence but optimality as well. Initial parameters of neural networks are as important as the network architecture and initialization has been thoroughly studied in the past. This report discusses the fusion …


Identification Of Phase-Based Key Performance Factors And Their Best Practices In Construction Projects, Mohammadreza Habibi May 2018

Identification Of Phase-Based Key Performance Factors And Their Best Practices In Construction Projects, Mohammadreza Habibi

Civil Engineering Theses - Archive

Delay and cost overrun in construction projects are two widespread problems arousing practitioners’ and scholars’ concerns as poor time and cost performance lead construction projects to failure. It is estimated that more than half of the construction industry’s projects encounter significant cost overruns and major delays, resulting in the industry having a tarnished reputation. Despite the attempts of numerous researchers to identify key performance factors, their results have been inconsistent. Most of the literature has focused solely on the construction phase budget and time overruns; the engineering/design and procurement phase costs and schedule performances have been rarely studied. Therefore, the …


Remaining Useful Life Prediction Of Water Pipes Using Artificial Neural Network And Adaptive Neuro Fuzzy Inference System Models, Razieh Tavakoli May 2018

Remaining Useful Life Prediction Of Water Pipes Using Artificial Neural Network And Adaptive Neuro Fuzzy Inference System Models, Razieh Tavakoli

Civil Engineering Dissertations - Archive

The U.S. water distribution system contains thousands of miles of pipes with differing materials, sizes, and ages. These pipes experience physical, environmental, structural and operational parameters that cause corrosion and eventually lead to their failures. The Remaining Useful Life (RUL) is the estimated time before a pipe will experience a failure mode specifically a pipe break. Pipe failure means collapse and deterioration of water pipes overtime. Pipe deterioration results in increased break rates, reduced hydraulic capacity, and detrimental impacts on water quality. Therefore, it is crucial to perform accurate models that can forecast deterioration rates along with estimates of remaining …


Comparison Of Ground Movements During Trenchless Technology Operations For Pipe And Box Installations By Numerical Analysis, Taha Ashoori May 2018

Comparison Of Ground Movements During Trenchless Technology Operations For Pipe And Box Installations By Numerical Analysis, Taha Ashoori

Civil Engineering Dissertations - Archive

Trenchless Technologies (TTs) are alternatives or methods of choice for the construction and renewal of buried pipe or box with little or no surface disruption. Specifically, TTs are used when other traditional methods, such as cut-and-cover methods are not physically possible. Other reasons for TT methods to be increasingly adopted by owners, engineers, and contractors are their low environmental impacts and, based on the project and the site conditions, lower costs per foot of installed pipe, making these technologies much more efficient and versatile with final results within a shorter time span. Trenchless technology methods are divided into two main …


Environmental Life Cycle Assessment Of Commercial Space Transportation Activities In The United States, Shelia Scott Neumann May 2018

Environmental Life Cycle Assessment Of Commercial Space Transportation Activities In The United States, Shelia Scott Neumann

Civil Engineering Dissertations - Archive

The Commercial Space Transportation (CST) activities in the United States are increasing and have increased over 50% in the last year. The launches in the United States for commercial purposes are expected to increase another 50% in the next 3-5 years. National Environmental Policy Act (NEPA) environmental assessments do provide the regulatory environmental analysis for launching space vehicles within the United States. However, the environmental impacts from these launches have not been fully characterized. One method to characterize environmental impacts from a system is through conducting a Life Cycle Assessment (LCA) based on an international standard, ISO14040. The results from …


Assessment Of Sustainability And Resilience In Transportation Infrastructure Geotechnics, Jasaswee T. Das May 2018

Assessment Of Sustainability And Resilience In Transportation Infrastructure Geotechnics, Jasaswee T. Das

Civil Engineering Dissertations - Archive

Transportation infrastructure, such as roads, embankments, bridges, railroads, airports, docks, and canals, serve as pathways for the mobility of people, goods, and services, and form the backbone of cities and communities. The construction, operation, and rehabilitation of these facilities put significant strain on the local, state, and federal agencies, including depletion of natural resources, and contributing to the global carbon footprint and greenhouse gas emissions. Further, these features stimulate anthropocentric development in a region which affects the land-use patterns and influences the demography of communities. In recent years, most transportation infrastructure are typically designed to withstand external and internal disturbances …


Detection And Prediction Of Defects In Composite Materials Using Di-Electric Characterization And Neural Networks, Muthu Ram Prabhu Elenchezhian, Aishwarya Nandini, Vamsee Vadlamudi, Rassel Raihan, Kenneth Reifsnider May 2018

Detection And Prediction Of Defects In Composite Materials Using Di-Electric Characterization And Neural Networks, Muthu Ram Prabhu Elenchezhian, Aishwarya Nandini, Vamsee Vadlamudi, Rassel Raihan, Kenneth Reifsnider

Institute of Predictive Performance Methodologies (IPPM-UTARI)-Archive

The state of art non-destructive inspection techniques for composite materials detect the presence of defects in the composite material, but they do not identify what type of defect it is, and hence, further visual inspection of the details are needed. This visual classification is a costly and time-consuming process, and it’s difficult to distinguish all of the defects effectively. Broadband Dielectric Spectroscopy (BbDS), has been an established tool for dielectric material characterization in polymer industries for a long time. Dielectric spectra of heterogeneous materials are altered by constituent interfaces, with changes in morphological heterogeneity, electrical and structural interactions between particles, …


Fea Of Carbon Composite As A Substitute For Steel (A992) In Case Of Square Or Rectangular Hollow Cross-Sections As Beams And Columns, Pradeep Ganesh Pai May 2018

Fea Of Carbon Composite As A Substitute For Steel (A992) In Case Of Square Or Rectangular Hollow Cross-Sections As Beams And Columns, Pradeep Ganesh Pai

Mechanical and Aerospace Engineering Theses - Archive

Improvement to an existing design is an ongoing and never-ending process in every field. The improvement can be in a myriad of areas like an increase in strength, reduction in weight, stiffness to a loading condition and so on. The way it is achieved can range from changing the properties of the material used by incorporating various manufacturing processes or by using an alternative material which can sustain the same loading conditions or for that matter, work better than the existing material. Composite materials like Carbon Fiber, Glass Fiber or Kevlar Fiber reinforced plastics, to name few, are being used …


Stochastic Finite Element Thermal Analysis Of A Ball Grid Array Package, Rahul Upreti May 2018

Stochastic Finite Element Thermal Analysis Of A Ball Grid Array Package, Rahul Upreti

Mechanical and Aerospace Engineering Theses - Archive

This study provides an insight into the factors which have a major impact on the probability of failure of a Ball Grid Array package. A stochastic finite element analysis was done on the package using First-order reliability method (FORM). The effects of uncertainty in material thermal conductivities, heat source, heat transfer coefficient and ambient temperature were studied. The average temperature at the die-junction interface was selected as failure criterion because the excess temperature at the junction is often a cause of failure. The performance of Finite Difference Method(FDM) and Semi-Analytic Complex Variable Method(SACVM) in computing sensitivities are compared. Results show …


Air Flow Pattern And Path Flow Simulation Of Airborne Particulate Contaminants In A Cold-Aisle Containment High-Density Data Center Utilizing Airside Economization, Gautham Thirunavakkarasu May 2018

Air Flow Pattern And Path Flow Simulation Of Airborne Particulate Contaminants In A Cold-Aisle Containment High-Density Data Center Utilizing Airside Economization, Gautham Thirunavakkarasu

Mechanical and Aerospace Engineering Theses - Archive

The energy used by Information Technology Equipment (ITE) and the supporting data center equipment keeps rising as data center expansion continues worldwide. To contain the rising operation costs, data center administrators are resorting to cost cutting measures by not adhering to the ambient data center environment standards. In many cases, free cooling techniques are adopted to partially or completely relieve the usage of refrigeration units, which adds to huge cost savings but also allows for the increased risk of particulate and gaseous contaminations. The ASHRAE TC9.9 subcommittee, on Mission Critical Facilities, Data Centers, Technology Spaces, and Electronic Equipment, has provided …


The Performance Of Quadrilateral Element With Rotational Degrees Of Freedom In Statics And Dynamics Analysis And Optimization, Xingzhi Wang May 2018

The Performance Of Quadrilateral Element With Rotational Degrees Of Freedom In Statics And Dynamics Analysis And Optimization, Xingzhi Wang

Mechanical and Aerospace Engineering Theses - Archive

Finite Element Method (FEM) is widely used in structural analysis, and the standard approach to increase the accuracy of analysis is increasing the total degrees of freedom (DOFs), namely, refine the mesh. By introducing the rotational DOFs, better accuracy can be achieved without change the mesh. The objective of this study was to investigate the performance of elements with rotational DOFs in statics and dynamics analysis and applying these elements to optimization. The implementation of three representative elements with rotational DOFs for statics analysis is reproduced. Also, this work implements these elements to dynamics analysis and optimization. The results show …


Computational Study Of Form Factor Of 3rd Generation Open Compute Servers Using Different Dielectric Fluids For Single-Phase Immersion Cooling, Pranavi Rachamreddy May 2018

Computational Study Of Form Factor Of 3rd Generation Open Compute Servers Using Different Dielectric Fluids For Single-Phase Immersion Cooling, Pranavi Rachamreddy

Mechanical and Aerospace Engineering Theses - Archive

Computer system dependency has been increased in the modern world and that has encouraged the rapid growth of data centers in leading business units like banking, education, transportation, social media and many more. Data center is a facility that incorporates an organisation’s IT operations and equipment, as well as where it stores, processes, and manages the data. To fulfil the demands of data storage and data processing, corresponding increase in power density of servers are needed. The data center energy efficiency largely depends on the thermal management of servers. Currently, air cooling is the most widely used thermal management technique …


Nanopore Biosensors For Molecular Detection And Analysis, Muhammad Usman Raza May 2018

Nanopore Biosensors For Molecular Detection And Analysis, Muhammad Usman Raza

Electrical Engineering Dissertations - Archive

Nanoscale fabrication techniques have led the march towards a new class of biosensors that were not possible to build in the past due to technological limitations. These molecular nanosensors can have biochemical, electromagnetic, acoustic, optical or electrophoretic detection modalities. One of these nanosensors, is solid state nanopores which use resistive pulse sensing in nanometer apertures in thin dielectric membranes. Solid state nanopores have been fabricated using cutting edge fabrication techniques to detect and analyze nanoscale biomolecules such as DNA, proteins, miRNA, viruses etc. These biosensors can be used as electronic sensors for biomarkers of certain diseases such as cancer and …


A New Adaptive Multiscale Approach For The Dynamic Modeling And Simulation Of Biomolecular Systems, Ashley Chase Guy May 2018

A New Adaptive Multiscale Approach For The Dynamic Modeling And Simulation Of Biomolecular Systems, Ashley Chase Guy

Mechanical and Aerospace Engineering Dissertations - Archive

This dissertation presents three developments in the simulation of sub-micron dynamical systems. First, a new thermostat formulation is shown to strictly enforce the constant temperature constraint necessary in many thermodynamic ensembles. This formulation also allows the system to quickly evolve to a low-potential state. Next, this new thermostat formulation is leveraged to extend a continuum-regime multiscale formulation to the atomistic regime allowing for equivalent time histories to be generated in significantly less computation time. Finally, an adaptive multiscale formulation allows for potential forces with time varying magnitudes to contribute to the overall dynamics similarly resulting in equivalent time histories in …


Robust Predictive Analytics For Determining Acclimation Parameter Of It Equipment, Premsanth Sadasivam May 2018

Robust Predictive Analytics For Determining Acclimation Parameter Of It Equipment, Premsanth Sadasivam

Mechanical and Aerospace Engineering Theses - Archive

Acclimation is the process in which an IT equipment adjusts to a change in its environment such as a change in temperature and humidity, allowing it to maintain performance across a range of environmental conditions. In commissioning of a new cold shipped IT equipment in data centers, environmental acclimation is an important step. Proper acclimation also minimizes the risk of powering on a machine that may still be wet due to moisture condensation. An experimental study is carried out to find how the acclimation occurs and the factors influencing it. These experiments are designed with various temperature ranges and using …


Optimizing A System Of Electric Vehicle Charging Stations, Ukesh Chawal May 2018

Optimizing A System Of Electric Vehicle Charging Stations, Ukesh Chawal

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

There has been a significant increase in the number of electric vehicles (EVs) mainly because of the need to have a greener living. Thus, ease of access to charging facilities is a prerequisite for large scale deployment for EV. The first component of this dissertation research seeks to formulate a deterministic mixed-integer linear programming (MILP) model to optimize the system of EV charging stations, the locations of the stations and the number of slots to be opened to maximize the profit based on the user-specified cost of opening a station. Despite giving the optimal solution, the drawback of MILP formulation …


Osteoprogenitor Cell Adhesion And Growth On The Bioactive Silicon Nitride Surface For Craniofacial Implants Applications, Kamal Awad May 2018

Osteoprogenitor Cell Adhesion And Growth On The Bioactive Silicon Nitride Surface For Craniofacial Implants Applications, Kamal Awad

Material Science and Engineering Theses - Archive

As a novel biomaterial, silicon nitride (Si3N4) has been used for orthopedic and spinal fusion applications. Its ability to promote continuity for structural support of missing bone, by in/on bone growth, gives it advantageous properties and potential for mandibular and craniofacial reconstruction applications. Yet, the surface properties of this material and its effect on the osteogenic properties have not been fully realized. Thus, the aim of this study was to evidently investigate the surface properties of the bioactive Si3N4 that enhance the calvarial osteoblasts cell adhesion, growth, and differentiation when compared to conventional implant materials such as titanium (Ti) and …


Nature Inspired Technology: A New Process For Silicification Based On Marine Sponges, Ami Atul Shah May 2018

Nature Inspired Technology: A New Process For Silicification Based On Marine Sponges, Ami Atul Shah

Material Science and Engineering Dissertations - Archive

Silica is used in various industries, ranging from automobile industry for tires to semiconductor industry, paints and coatings, biomedical devices & applications to food & drug industry. The current processing techniques for precipitated silica involve harsh conditions like high temperature and extreme pH conditions. Nature already has highly evolved production techniques for silica. They run at physiological conditions and exhibit intricate control over the synthesis, leading to very pure and ornate siliceous structures. These structures exhibit organized architecture at scales as small as nano-dimensions. The proposed research work is a step, towards development of new techniques that bio-mimic the silica …


Investigation Of The Processing-Structure-Property Relationship In Ta-Si-N Nanocomposite Coatings, Anna Zaman May 2018

Investigation Of The Processing-Structure-Property Relationship In Ta-Si-N Nanocomposite Coatings, Anna Zaman

Material Science and Engineering Dissertations - Archive

The present-day industry demands development of coatings for harsh environmental applications which can resist impact and oxidation at high temperatures. It is vitally important to develop new hard (>30 GPa) protective coatings which will be thermally stable at temperatures, T > 800 °C and simultaneously will ensure a good protection of the substrate against oxidation from an external atmosphere. The limitations of conventional coatings due to inferior hardness or poor oxidation stability can be overcome by nanocomposite coatings as they exhibit enhanced and completely new properties. To address this requirement of new enhanced protective systems, there is a need to …


Dielectric Property Investigation Of Degraded Pre-Preg And Performance Prediction Of The Final Composite Part, Aishwarya Nandini, Nina Shute, Muthu Ram Prabhu Elenchezhian, Vamsee Vadlamudi, Rassel Raihan, Kenneth Reifsnider May 2018

Dielectric Property Investigation Of Degraded Pre-Preg And Performance Prediction Of The Final Composite Part, Aishwarya Nandini, Nina Shute, Muthu Ram Prabhu Elenchezhian, Vamsee Vadlamudi, Rassel Raihan, Kenneth Reifsnider

Institute of Predictive Performance Methodologies (IPPM-UTARI)-Archive

In recent years, fiber-reinforced (i.e., Glass, Carbon, Kevlar) epoxy composites are used widely in structural applications ranging from military and civil aircraft production to recreational consumer products. Most of the industries use pre-impregnated varieties of composite (prepregs) to make high-quality composite parts. Despite their various advantages, prepreg materials are unstable at ambient temperature. A realistic estimation of the shelf life of prepreg is therefore essential for maintaining quality while reducing wastage of resources. Prepregs are temperature and moisture sensitive material systems. To achieve prolonged shelf life, manufacturer and seller of the prepreg must store the materials at zero degrees Celsius …


Framework For Determining The Pullout Resistance Of Inextensible 2-Wire Soil-Reinforcing Elements Embedded In Sand, Thomas Patrick Taylor May 2018

Framework For Determining The Pullout Resistance Of Inextensible 2-Wire Soil-Reinforcing Elements Embedded In Sand, Thomas Patrick Taylor

Civil Engineering Dissertations - Archive

Mechanically Stabilized Earth (MSE) has been successfully used as a commercial retaining structure since its development in 1963 by Henry Vidal (Schlosser 1990). MSE is a ground improvement system that consists of soil-reinforcing, compacted backfill, and a facing. The initial soil-reinforcing developed for commercial use by Vidal consisted of a smooth steel strip. Since then, a diverse range of soil-reinforcing has been developed, including extensible and inextensible reinforcing. The various geometric configurations of soil-reinforcing have included wide width and narrow width elements comprising planar strips, planar grids, co-planar strips, co-planar grids, and wide sheets. General specifications categorize inextensible soil-reinforcing into …


Effects Of Build Parameters On The Mechanical And Di-Electrical Properties Of Am Parts, Sai Sri Munaganuru, Muthu Ram Prabhu Elenchezhian, Vamsee Vadlamudi, Rauhon Ahmed Shaik, Hari K. Adluru, Rassel Raihan Jan 2018

Effects Of Build Parameters On The Mechanical And Di-Electrical Properties Of Am Parts, Sai Sri Munaganuru, Muthu Ram Prabhu Elenchezhian, Vamsee Vadlamudi, Rauhon Ahmed Shaik, Hari K. Adluru, Rassel Raihan

Institute of Predictive Performance Methodologies (IPPM-UTARI)-Archive

Additive manufacturing (AM) revolutionized many industries, i.e., Automotive, Biomedical, Aerospace and Defense. As opposed to traditional manufacturing methods, a part is manufactured layer by layer from 3D CAD models in AM. Though the vision of AM is impressive, there are many challenges that are hindering the widespread use of these complex parts. One of the challenges in these materials is defects grow and their orientation during the manufacturing process. In this paper we are going to investigate the effect of Build Parameters and their effects on the mechanical and electrical properties of the additively manufactured heterogeneous material system. We will …


Mcnair Scholars Research Journal 2018, Ryne Dingler, Efret M. Ghirmazion, Paola M. Iracheta, Regan Kubicek, Henry Alvarez, Jazmyn Barajas-Trujillo, Julian Beatty, Enriqueta Calderon, Silvia Chapa, Dominic French, Octavio Miranda, Mariah Ochoa, Susana Pimentel, Elida E. Sorto-Ramos, Andrew Soto-Levins Jan 2018

Mcnair Scholars Research Journal 2018, Ryne Dingler, Efret M. Ghirmazion, Paola M. Iracheta, Regan Kubicek, Henry Alvarez, Jazmyn Barajas-Trujillo, Julian Beatty, Enriqueta Calderon, Silvia Chapa, Dominic French, Octavio Miranda, Mariah Ochoa, Susana Pimentel, Elida E. Sorto-Ramos, Andrew Soto-Levins

McNair Scholars Research Journal-Archive

No abstract provided.


Data Driven Composites: The Challenge And Paths Forwards, Muthu Ram Prabhu Elenchezhian, Vamsee Vadlamudi, Rassel Raihan, Kenneth Reifsnider Jan 2018

Data Driven Composites: The Challenge And Paths Forwards, Muthu Ram Prabhu Elenchezhian, Vamsee Vadlamudi, Rassel Raihan, Kenneth Reifsnider

Institute of Predictive Performance Methodologies (IPPM-UTARI)-Archive

The concept of “data driven” grew out of the general subject of data analytics, especially in the business world. The classical sequence proposed by Dykes (2010) shown below illustrates the general contents of the concept. Indeed, the idea of “predictive modeling” of the future behavior of a system has strong roots in the business community. In general, for engineering and other fields, the data driven challenge is to use the past with information from the present to predict the future behavior of a system. In turn, the user must pay for collection and processing, hosting and maintenance of the data, …


State Variable Methods Of Assessment, Prognosis, And Control Of Composite And Bonded Structures, Kenneth Reifsnider, Rassel Raihan, Vamsee Vadlamudi, Muthu Ram Prabhu Elenchezhian Jan 2018

State Variable Methods Of Assessment, Prognosis, And Control Of Composite And Bonded Structures, Kenneth Reifsnider, Rassel Raihan, Vamsee Vadlamudi, Muthu Ram Prabhu Elenchezhian

Institute of Predictive Performance Methodologies (IPPM-UTARI)-Archive

It is generally recognized that the determination of material state is the baseline foundation for the assessment and prognosis of current and future performance of structural materials in which distributed damage leads to progressive property degradation. Many classes of composite materials, both naturally occurring and engineering designs, are governed by such behavior. However, finding appropriate measureable physical variables to make such assessments, especially for as-manufactured and subsequent real-time assessment and prognosis conditions is challenging. Measurement and analysis of multiple single defect initiation, interaction, and collective effects is the most rigorous current methodology, and is the foundation for certification and quality …


Global Prediction Of Discrete Local Damage Interactions Using Broadband Dielectric Spectroscopy, Vamsee Vadlamudi, Muthu Ram Prabhu Elenchezhian, Rauhon Ahmed Shaik, Aishwarya Nandini, Rassel Raihan, Kenneth Reifsnider Jan 2018

Global Prediction Of Discrete Local Damage Interactions Using Broadband Dielectric Spectroscopy, Vamsee Vadlamudi, Muthu Ram Prabhu Elenchezhian, Rauhon Ahmed Shaik, Aishwarya Nandini, Rassel Raihan, Kenneth Reifsnider

Institute of Predictive Performance Methodologies (IPPM-UTARI)-Archive

With the increasing demand for composites in many modern applications, it is important to predict the initiation of failure events. Due to the heterogeneous nature of these materials, a single damage mode will not lead to final failure, hence detecting the initiation and growth of a single crack (defect) will not yield accurate predictions of the strength or the material state. It is important to capture the interaction of various damage modes that tend to change the material state leading to initiation of failure. To assess the material state, one needs to determine the appropriate global physical variables that can …


Molecular Dynamics For The Prediction Of The Interfacial Shear Stress And Interface Dielectric Properties Of Carbon Fiber Epoxy Composites, Rajni Chahal, Ashfaq Adnan, Kenneth Reifsnider, Rassel Raihan, Yuan Ting Wu, Vamsee Vadlamudi, Muthu Ram Prabhu Elenchezhian Jan 2018

Molecular Dynamics For The Prediction Of The Interfacial Shear Stress And Interface Dielectric Properties Of Carbon Fiber Epoxy Composites, Rajni Chahal, Ashfaq Adnan, Kenneth Reifsnider, Rassel Raihan, Yuan Ting Wu, Vamsee Vadlamudi, Muthu Ram Prabhu Elenchezhian

Institute of Predictive Performance Methodologies (IPPM-UTARI)-Archive

The thermoset epoxy resin Diglycidyl ether of Bisphenol F (EPON 862), crosslinked with the Diethylene Toluene Diamine (DETDA) hardening agent, are utilized as the polymer matrix component in many graphite (carbon fiber) composites. Since it is difficult to experimentally characterize the interfacial region, computational molecular modeling is a necessary tool for understanding the influence of the interfacial molecular structure on bulk-level material properties. The purpose of this research is to evaluate and compare the interfacial shear stress and dipole moment for the pristine carbon fiber composite and the one with the moisture content at the interface. Molecular models are established …


Label-Free Refractive Index Sensing With Free-Space Coupled Photonic Crystal Slabs, Yonghao Liu Dec 2017

Label-Free Refractive Index Sensing With Free-Space Coupled Photonic Crystal Slabs, Yonghao Liu

Electrical Engineering Dissertations - Archive

Label-free optical resonance sensors can detect small changes of refractive index (RI), which could be used for biochemical molecular detection, drug screening or gas detection. One of the most critical parameters in these sensors is the sensor detection limit (DL). Reducing DL can be achieved by increasing the resonance quality factors (Q) and the spectral sensitivity (S). Another critical research challenge in these sensors is the sensing specificity. In this thesis, based on Fano resonance principle in two-dimensional photonic crystal slabs (PCS) and the integration with gas separation columns, we investigated various free-space coupled on-chip optical resonance sensors for both …


Label Free Optical Detection Of Electrical Activity In Mammalian Neurons, Sarmishtha Satpathy Dec 2017

Label Free Optical Detection Of Electrical Activity In Mammalian Neurons, Sarmishtha Satpathy

Electrical Engineering Dissertations - Archive

We describe an optical technique for label-free detection of the action potential in cultured mammalian neurons. Induced morphological changes due to action potential propagation in neurons are optically interrogated with a phase sensitive interferometric technique. Optical recordings composed of signal pulses mirror the electrical spike train activity of individual neurons in a network. The optical pulses are transient nanoscale oscillatory changes in the optical path length of varying peak magnitude and temporal width. Exogenous application of glutamate to cortical neuronal cultures produced coincident increase in the electrical and optical activity; both were blocked by application of a Na-channel blocker, Tetrodotoxin. …


Large Dimensional Analysis And Optimization For Massive Mimo Wireless Networks, Longwei Wang Dec 2017

Large Dimensional Analysis And Optimization For Massive Mimo Wireless Networks, Longwei Wang

Electrical Engineering Dissertations - Archive

The Last decade has seen a massive growth of wireless devices. Demands for high capacity and massive connectivity always increases. To meet the these requirements, massive multiple-input multiple-output (MIMO) technology is proposed for the next generation wireless systems. With massive antenna arrays at the BS, the channel vectors between the users and the BS are asymptotically orthogonal, and the intercell interference can be eliminated with simple linear processing method. The effects of fast fading, and uncorrelated noise tend to disappear as the number of BS station antennas grows large. In this thesis, we mainly focus on the performance analysis and …