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Full-Text Articles in Engineering

Distributed Methods For Composite Optimization: Communication Efficiency, Load-Balancing And Local Solvers, Chenxin Ma Sep 2018

Distributed Methods For Composite Optimization: Communication Efficiency, Load-Balancing And Local Solvers, Chenxin Ma

Theses and Dissertations

The scale of modern datasets necessitates the development of efficient distributed opti- mization methods for composite problems, which have numerous applications in the field of machine learning. A critical challenge in realizing this promise of scalability is to develop efficient methods for communicating and coordinating information between distributed ma- chines, taking into account the specific needs of machine learning algorithms. Recent work in this area has been limited by focusing heavily on developing highly specific methods for the distributed environment. These special-purpose methods are often unable to fully leverage the competitive performance of their well-tuned and customized single machine counterparts ...


Characterizing Targeted Therapeutic Delivery And Cellular Dynamics Using In Vitro Cancer Disease Models, Christopher George Uhl Aug 2018

Characterizing Targeted Therapeutic Delivery And Cellular Dynamics Using In Vitro Cancer Disease Models, Christopher George Uhl

Theses and Dissertations

Cancer is a significant health risk to people living in developed and developing countries, which continues to prove difficult to treat. Common treatment options of cancers include surgical removal, radiation, and chemotherapies, which are often used in combination to improve the likelihood of successful treatment. Such combinatory approaches towards treatment are often taken because each approach is not targeted enough to function perfectly on its own. Being able to delivery therapeutic loads in a more targeted manner to sites of cancer has the capability of improving therapeutic efficiency and improving patient responses. The development of improved therapeutic delivery vehicles and ...


Grain Size Effects On Viscoelastic Relaxation Of Sub-Micron Thickness Fcc Metallic Films, Jeffrey Smyth Aug 2018

Grain Size Effects On Viscoelastic Relaxation Of Sub-Micron Thickness Fcc Metallic Films, Jeffrey Smyth

Theses and Dissertations

Sub-micron thickness metallic thin films are known to exhibit mechanical size effects, where the thin film mechanical behavior can differ significantly from that of a bulk version of the same material. One such mechanical behavior, and the focus of this work, is the unique thin film viscoelastic deformation response to sub-yield, low-strain stimuli in near-ambient temperature environments. In engineering components using bulk materials, strains within the elastic regime are generally considered instantaneous. It is only at higher operating temperatures that temporal deformation processes, such as creep, are considered in bulk component design. However, in Micro-Electro-Mechanical Systems (MEMS), specifically Radio Frequency ...


Fine-Grained Visual Representation Learning With Deep Neural Networks, Tao Xu Aug 2018

Fine-Grained Visual Representation Learning With Deep Neural Networks, Tao Xu

Theses and Dissertations

Representation learning is about learning representative features of the data that make it easier to extract useful information for the subsequent learning task. Due to the great success of deep learning, representations learned by deep neural networks have shown significant improvement than handcrafted features on most learning tasks. However, it is still very challenging to learn fine-grained visual representations, which refer to highly localized features extracted from images that are useful for image understanding tasks, such as fine-grained recognition, image generation and semantic segmentation. Fine-grained recognition identifies subtle visual differences to distinguish among subordinate categories; image generation learns fine-grained visual ...


The Mechanical Performance And Microstructure Development Of Laser Beam Welds And Post Weld Heat Treatment Of Ti 1023 Alloy, Meng Fu Huang Aug 2018

The Mechanical Performance And Microstructure Development Of Laser Beam Welds And Post Weld Heat Treatment Of Ti 1023 Alloy, Meng Fu Huang

Theses and Dissertations

Titanium alloys are widely used in the aerospace industry. For example, most components of the Boeing 777 landing gear are made of the Ti-10V-2Fe-3Al (Ti1023) alloy due to its lighweight and superior mechanical strength. In addition, because Titanium is chemicaly active element, when jointing the Ti alloy components, the laser beam welding (LBW) has been selected for avoiding the eventual contaminations and narrowing the heat affected zone by the presence of its protected atmosphere and low heat input. However, there is a lack of reported research results about welded Ti1023 alloy, particularly laser beam welding. Therefore, the microstructure and mechanical ...


Aberration Corrected Analytical Electron Microscopy Studies Of Nanometallic Catalysts, Sultan Althahban Aug 2018

Aberration Corrected Analytical Electron Microscopy Studies Of Nanometallic Catalysts, Sultan Althahban

Theses and Dissertations

Catalysis by nanoscopic metal structures, ranging from nanoparticles to sub-nm clusters and even individual atoms, is amongst the most intensely studied topics in nanoscience. The catalytic performance of supported metal nanoparticles is governed by their crysallographic structure, shape, size, composition and interaction with the support. Aberration-corrected scanning transmission electron microscopy (AC-STEM), with its ultra-high spatial resolution for imaging and compositional analysis, is an ideal tool for characterizing such features in metallic nanocatalysts. In this thesis, five case studies are presented where AC-STEM has been invaluable in elucidating synthesis route - structure - performance relationships in some technologically important catalyst systems.


Computational Study Of Free Jets Emanating From Circular And Lobed Orifice-Lattice Boltzmann Method, Yang Chen Aug 2018

Computational Study Of Free Jets Emanating From Circular And Lobed Orifice-Lattice Boltzmann Method, Yang Chen

Theses and Dissertations

The Lattice Boltzmann method is an effective computational fluid dynamics tool to study complex flows. Unlike conventional numerical schemes based on discretization of macroscopic continuum equations, the Lattice Boltzmann method is based on particles and mesoscopic kinetic equations. Single-Relaxation Time Lattice Boltzmann Method (SRTLBM) with Smagorinsky LES model is applied to simulate high Reynolds number jet flows of single and multiphase flows emanating. The multi-block approach is implemented to refine the mesh when the high resolution is needed in the region around the core jet. An 2nd order accurate interface treatment between neighboring blocks is derived to satisfy the conservation ...


Large Eddy Simulations Of Ventilated Micro-Hydrokinetic Turbine And Pump-Turbines, Cosan Daskiran Aug 2018

Large Eddy Simulations Of Ventilated Micro-Hydrokinetic Turbine And Pump-Turbines, Cosan Daskiran

Theses and Dissertations

Large eddy simulations of ventilated hydrokinetic turbine and pump-turbine are conducted. The mathematical modeling of oxygen dissolution and the flow model employed were validated by comparing predicted dissolved oxygen concentration against reported experimental measurements. A parametric study is performed to investigate the influence of interfacial forces, surface tension and bubble breakage and coalescence terms. It is demonstrated that aeration via hydrokinetic turbines can be used to improve the dissolved oxygen level in rivers for better water quality. It is also shown that aeration can effectively be achieved via the pump-turbine system to provide the desired dissolved oxygen level for the ...


Privacy In Dynamical Systems And Networks: Anonymous Routing And Retail Competition, Omid Javidbakht Aug 2018

Privacy In Dynamical Systems And Networks: Anonymous Routing And Retail Competition, Omid Javidbakht

Theses and Dissertations

Tradeoffs between privacy and utilities, and privacy preserving control mechanisms in dynamical systems and networks are studied in this dissertation. Despite security mechanisms and data encryption, these systems are still vulnerable to timing analysis, wherein an eavesdropper can use these observations to interpret the identity of individuals. Motivated by this vulnerability, the first three topics of this dissertation investigates privacy preserving mechanisms in dynamical systems and network. The last chapter studies the effect of privacy awareness of consumers on retail competition.The first topic of this dissertation studies the tradeoff between delay and packet source anonymity in a network of ...


Hybrid Ion Exchange Processes For Sustainable Softening And Marcellus Flowback Treatment, Jinze Li Aug 2018

Hybrid Ion Exchange Processes For Sustainable Softening And Marcellus Flowback Treatment, Jinze Li

Theses and Dissertations

Hybrid ion exchange technology has been applied in many environmental aspects nowadays due to its high treatment efficiency, reusability, customizable selectivity, operational stability, and low cost. Under certain circumstances, ion exchange technology is a favorable substitute for traditional treatment process, and its applications in industries are continually growing.Water hardness is a concern for many industrial and municipal unit operations, which could result in surface scaling of heat transfer equipment or membranes. Sodium exchange softening, although commonly used, has caused serious pollution to local ecological and water environments due to its discharge of high salinity spent regenerant. Many arid areas ...


A Service System With On-Demand Agents, Stochastic Gradient Algorithms And The Sarah Algorithm, Lam Nguyen Aug 2018

A Service System With On-Demand Agents, Stochastic Gradient Algorithms And The Sarah Algorithm, Lam Nguyen

Theses and Dissertations

We consider a system, where a random flow of customers is served by agents invited on-demand. Each invited agent arrives into the system after a random time, and leaves it with some probability after each service completion. Customers and/or agents may be impatient. The objective is to design a real-time adaptive invitation scheme that minimizes customer and agent waiting times.We study some aspects of the SGD method with a fixed, large learning rate and propose a novel assumption of the objective function, under which this method has improved convergence rates. We also propose a convergence analysis of SGD ...


The Resilience Of Smart Energy Systems Against Adversarial Attacks, Operational Degradation And Variabilities, Parth Pradhan Aug 2018

The Resilience Of Smart Energy Systems Against Adversarial Attacks, Operational Degradation And Variabilities, Parth Pradhan

Theses and Dissertations

The presented research investigates selected topics concerning resilience of critical energy infrastructures against certain types of operational disturbances and/or failures whether natural or man-made. A system is made resilient through the deployment of physical devices enabling real-time monitoring, strong feedback control system, advanced system security and protection strategies or through prompt and accurate man-made actions or both. Our work seeks to develop well-planned strategies that act as a foundation for such resiliency enabling techniques.The research conducted thus far addresses three attributes of a resilient system, namely security, efficiency, and robustness, for three types of systems associated with current ...


Fixed Bed Reactor Design For Thermochemical Energy Storage Using Ca(Oh)2 /Cao, Qasim Ranjha Aug 2018

Fixed Bed Reactor Design For Thermochemical Energy Storage Using Ca(Oh)2 /Cao, Qasim Ranjha

Theses and Dissertations

Thermochemical energy storage (TCES) is an attractive mode of storing the solar energy in the form of heat to be used with concentrated solar power (CSP) plants. Thermal energy is stored/released using a reverse endothermic/ exothermic reaction. TCES offers clear advantages over the other thermal energy storage (TES) options with sensible heat storage (SHS) and latent heat storage (LHS) in terms of energy density, storage time and the temperature range for thermal energy storage. However, this technique of storing the solar power at higher temperatures is still at laboratory or pilot scale, and researchers are trying to develop viable ...


Computational Study Of Desalination By Membranes, Mustafa Usta Aug 2018

Computational Study Of Desalination By Membranes, Mustafa Usta

Theses and Dissertations

Water desalination by membranes constitutes the majority of the low-quality water purication systems that extends across many different techniques. This study considers transport phenomena in reverse osmosis (RO) and vacuum membrane distillation (VMD) modules using computational techniques. Reverse osmosis is a pressure-driven separation method using semi-permeable membranes featuring nanoporous structures. Vacuum membrane distillation is another emerging separation method relying on the temperature difference across the microporous hydrophobic membranes.The membrane separation process intrinsically gives rise to temperature polarization (TP) and concentration polarization (CP) which could be severe limitations in these systems. To eliminate these polarizations and increase the module performance ...


Tibial Fracture Nonunions Following Intramedullary Nailing: An Application Of Logistic Regression, Katherine Wu May 2018

Tibial Fracture Nonunions Following Intramedullary Nailing: An Application Of Logistic Regression, Katherine Wu

Eckardt Scholars Projects

This paper utilizes the principles of logistic regression analysis to study patient factors that are strongly linked to the outcome of intramedullary nail surgery. This surgery is performed on fractured tibial bones to bring the bone back to union, or a state of connection again. The alternative result of the surgery is nonunion, or a state in which the bone does not heal properly. This paper draws from a recent publication in the Journal of Orthopedic Trauma, “Tibial fracture nonunion and time to healing following reamed intramedullary nailing” (Dailey, Wu, Wu, McQueen, & Court-Brown, 2018).


A Novel Dielectrophoresis Potential Spectroscopy For Colloidal Nanoparticles, Hao Huang May 2018

A Novel Dielectrophoresis Potential Spectroscopy For Colloidal Nanoparticles, Hao Huang

Theses and Dissertations

Dielectrophoresis (DEP) has been widely used to manipulate nanoparticles in microfluidic applications. However, determination of the DEP force of nanoparticles by theoretical models is not easy due to complications caused by the polarization of electrical double layer (EDL). Additionally, there is a lack of suitable experimental techniques to quantify the DEP force of nanoparticles. This paper reports a statistical mechanics-based experimental method to determine the DEP potential energy of a single particle by measuring the equilibrium number density of particles in a DEP force field. Results show that at high frequencies, the measured potentials agree with the Maxwell-Wagner-O’Konski (MWO ...


Processing Of Bio-Polymer Based Nanocomposite For Fused Filament Fabrication, Osama Mohammad Khayat May 2018

Processing Of Bio-Polymer Based Nanocomposite For Fused Filament Fabrication, Osama Mohammad Khayat

Theses and Dissertations

Polylactic acid (PLA) is perhaps one of the best known polymers produced from renewable raw materials such as sugar cane and corn starch. Several studies have focused on improving the properties of PLA by incorporating nanofillers in polymer matrix. Cellulose nanocrystals (CNC) is a nanofiller from natural sources (typically wood pulp) that is used to reinforce and modify the mechanical properties and biodegradability of PLA. In this work, cellulose nanocrystals (CNC) reinforced polylactic acid composite was produced in 1, 2, 5 and 10 wt % CNC content by a single-screw extruder in filament form. The effect of cellulose content on the ...


Imaging Depth Enhancement On Tumor Spheroid By Optical Clearing In Optical Coherence Tomography And Confocal Microscopy, Jinyun Zou May 2018

Imaging Depth Enhancement On Tumor Spheroid By Optical Clearing In Optical Coherence Tomography And Confocal Microscopy, Jinyun Zou

Theses and Dissertations

The tumor spheroid is becoming a promising model for cancer preclinical drugs test. However, its opacity limits the application of high-resolution imaging modalities to explore the inner core region of a spheroid. In this study, a fast aqueous optical clearing method, ScaleSQ(5), was applied to tumor spheroids achieving tissue transparency for deeper light penetration. The imaging depth enhancement was examined by confocal fluorescence microscopy and optical coherence tomography respectively. As a result, tissue transparency is achieved and the light penetration is enhanced by 61.81% in confocal fluorescence microscopy, and 57.13% in optical coherence tomography. Also, ScaleSQ(5 ...


Wafer-Scale Fabrication And Characterization Of Recessed-Channel Ptse2 Mosfets With Low Contact Resistance And Improved Gate Control, Lei Li May 2018

Wafer-Scale Fabrication And Characterization Of Recessed-Channel Ptse2 Mosfets With Low Contact Resistance And Improved Gate Control, Lei Li

Theses and Dissertations

For the first time, wafer-scale fabrication of PtSe2 MOSFETs was demonstrated by photolithography. The on PtSe2 is grown by thermally assisted conversion (TAC) of Pt films under Se vapor at 400 °C. Taking advantage of the unique property of PtSe2 to transition from semiconductor to semimetal as its thickness increases beyond a few monolayers, channel recess was adapted for improving gate control while keeping the contact resistance as low as 0.008 Ω∙cm. The wafer-scale fabrication resulted in uniform device characteristics so that average vs. best results were reported, as well as RF vs. DC characteristics. For example, the ...


Detection And Modeling Of Wind Ramp Events In Smart Grid, Xingbang Du May 2018

Detection And Modeling Of Wind Ramp Events In Smart Grid, Xingbang Du

Theses and Dissertations

Wind ramp events have a significant influence of uncertainty in wind power production. In order to build an efficient decision-making systems for the smart grid, developing statistical models based on analysis of historical data of wind ramp events is indispensable. In this paper, we design a detection algorithm to analyze historical data, build distribution models to predict and simulate wind ramp events. Phase-type distribution consists of a convolution of the Exponential distribution which can be used to apply Markov decisions process and identify the factors which can cause wind ramp events. We use three types of Phase-type distribution to fit ...


Real-Time Modeling Of Gas-Electric Dependencies: An Optimal Control Approach, Qinxu Gu May 2018

Real-Time Modeling Of Gas-Electric Dependencies: An Optimal Control Approach, Qinxu Gu

Theses and Dissertations

In this thesis, several turbine-governor models such as GAST model and GGOV1 model are implemented. The simulation of the models takes electric power and speed as the variable input, respectively, to see what will influence the fuel consumption and mechanical power. These two models are implemented in detail and incorporated with non-windup limiters. Different implementations for the non-windup limiters are considered and compared. In addition to the single gas turbine model, its integration to a power system model is developed as well. We consider two-area systems, one with simple primary speed droop control and one with supplementary automatic generation control.


Virtual Structural Analysis Of Bone Fracture Healing From Low-Dose Clinical Ct Scans, Peter Schwarzenberg May 2018

Virtual Structural Analysis Of Bone Fracture Healing From Low-Dose Clinical Ct Scans, Peter Schwarzenberg

Theses and Dissertations

Bone fractures often heal by forming a soft external bridge called a callus, which gradually hardens over time and restores the structural stiffness of the bone. In clinical studies focused on bone healing, healing progress is usually tracked using subjective assessments such as pain and mobility scores, qualitative observations of callus on X-rays, and incidence of complications such as implant fatigue failure. This data can be highly variable, leading to study designs that require very large multi-center trials with thousands of cases to detect differences between groups.Accordingly, the purpose of this thesis is to propose a new technique for ...


Shape Control Of A Spatial Cable, Bo Tian May 2018

Shape Control Of A Spatial Cable, Bo Tian

Theses and Dissertations

Unmanned Aerial Vehicles (UAVs) have been widely used in scientific, industrial and military applications. Rotorcrafts, such as quadcopters, are agile and versatile in their applications. However one of the biggest challenges with such UAVs is their limited battery life that make the flight time for a typical UAVs limited to twenty to thirty minutes for most practical purposes. A solution to this problem lies in the use of cables that tether the UAV to a power outlet for constant power supply. However, the cable needs to be controlled effectively in order to avoid obstacles or other UAVs. In this thesis ...


Calculating Vacancy Positions To Optiamally Assign Recruits Of The Rok Army, Doheon Han May 2018

Calculating Vacancy Positions To Optiamally Assign Recruits Of The Rok Army, Doheon Han

Theses and Dissertations

Since the number of troops in the ROK Army will gradually decrease, efficient personnel assignment is required to improve the level of combat power. Therefore, the process of assigning recruits will become more important. In the current system, the calculation of the vacancy positions for assigning recruits is performed manually by a person. Thus, the occurrence of mistakes in the process and the inefficiencies of the calculation results are inevitable problems. In particular, imbalances due to deviations among combat powers after the assignment of recruits can be a major problem. The purpose of the new model presented in this paper ...


Design And Manufacturing Of A High Performance Indoor Quadcopter, Guangyi Liu May 2018

Design And Manufacturing Of A High Performance Indoor Quadcopter, Guangyi Liu

Theses and Dissertations

In DCDS (Distributed Control and Dynamical Systems) laboratory, we are using quadcopter flying inside the building with motion capture system. In the quadcopter base, we are designing a new flight controller which has a high-speed processor and fast Wi-Fi communication. And the price is affordable in case of crashes during the research.The IMU used on the quadcopter is MPU6050 and HMC5883L magnetometer, they provide accurate Euler angle, angular velocity and heading at 200Hz. The controller used for attitude is cascade PID controller which controls the angle and the angular velocity at the same time, it’s robust and reliable ...


Effects Of Free-Stream Turbulence On Tidal Turbine Blade Performance And Wake, Angela Marie Lawrence May 2018

Effects Of Free-Stream Turbulence On Tidal Turbine Blade Performance And Wake, Angela Marie Lawrence

Theses and Dissertations

Tidal turbines operate inflow conditions with elevated levels of free-stream turbulence (FST) that affect the loads acting on components, which in turn affects the performance. The current work focuses on the use of controlled laboratory experiments to investigate the effects of free-stream turbulence on an SG-6043 turbine blade section. Elevated levels of FST are generated using an active grid generator at turbulence intensities (Ti) varying between 1.5-18%. It was observed that elevated levels of FST increased the coefficient of lift and caused a subsequent delay in flow separation. In addition, the coefficient of drag also increases at high angles ...


Investigation Of Elastoplastic Ratchetting Behavior Of Stainless Steel 316 Under Cyclic Uniaxial Asymmetric Loading At Room Temperature, Sirui Li May 2018

Investigation Of Elastoplastic Ratchetting Behavior Of Stainless Steel 316 Under Cyclic Uniaxial Asymmetric Loading At Room Temperature, Sirui Li

Theses and Dissertations

This work investigates, both experimentally and computationally the cyclic behavior of stainless steel 316 under uniaxial loading at room temperature. Elastoplastic investigations of SS 316 are important in the development of an understanding of the possible behavior and their contribution to the material performance under cyclic loading. Cyclic plasticity can occur in an SS 316 component or structure depending on the loading conditions. Therefore, it is vital that the cyclic behavior of SS 316 is recognized and understood. In particular SS316 cylindrical rods specimens were tested under uniaxial cyclic loading. The experimental results show that ratchetting behavior regimes exist under ...


A Design Proposal For A Novel Gun-Launched Unmanned Aerial System, Douglas Bahr Rumbaugh, Jr. May 2018

A Design Proposal For A Novel Gun-Launched Unmanned Aerial System, Douglas Bahr Rumbaugh, Jr.

Theses and Dissertations

A proposed design for a gun-launched, unmanned aerial system (GLUAS) is presented, along with experimental data pertaining to the characterization of said design, and specifically targeted towards improving its aerodynamics through an examination of planform shape and wing flexibility.The proposed design consists of a deployable wing micro-aerial vehicle (MAV) that can fit inside of a 60mm mortar shell. The wings consist of 5 individual segments on each side, which stack on top of one another within the body, and are deployed by a torsion spring and an interlocking system of gears and bosses. These wings form a roughly semi-circular ...


Stress Relief Cracking Susceptibility In High Temperature Alloys, Rishi Kant May 2018

Stress Relief Cracking Susceptibility In High Temperature Alloys, Rishi Kant

Theses and Dissertations

The stress relief cracking (SRC) susceptibility of a range of austenitic and ferritic alloys was tested using Gleeble® based test procedures. The tests were developed to study the effect of post weld heat treatment (PWHT) temperature and cold working on the SRC susceptibility. Six susceptibility parameters were identified from the test results (ductility, percentage stress relaxed, hardness increase at fracture, failure time, fracture mode and extent/type of secondary cracks below the fracture). The susceptibility parameters were integrated with concepts of Risk Priority Number (tool in 6-Sigma) to develop an SRC susceptibility index. Sensitivity analysis of the methodology was done ...


Fatigue Investigation Of Slit Rib-To-Floor Beam Connections In Steel Orthotropic Bridge Decks, Jayne Marks May 2018

Fatigue Investigation Of Slit Rib-To-Floor Beam Connections In Steel Orthotropic Bridge Decks, Jayne Marks

Theses and Dissertations

The steel orthotropic bridge deck (SOBD) is a bridge deck system which consists of longitudinal open or closed ribs that pass through transverse floor beams with a continuous steel deck plate on top. All of these components are joined using welded connections which can be costly to fabricate and prone to fatigue cracks. The rib-to-floor beam (RFB) connection in an SOBD is labor intensive and fatigue sensitive. In the past, the RFB connection has either been a fully fitted connection or a connection with an extended cut-out which is larger than the opening in the floor beam web for the ...