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2019

Theses/Dissertations

Washington University in St. Louis

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Articles 1 - 20 of 20

Full-Text Articles in Engineering

Numerical Simulation Of Flow Past Naca 0012 Airfoil Using A Co-Flow Jet At Different Injection Angles To Control Lift And Drag, Da Xiao May 2019

Numerical Simulation Of Flow Past Naca 0012 Airfoil Using A Co-Flow Jet At Different Injection Angles To Control Lift And Drag, Da Xiao

Engineering and Applied Science Theses & Dissertations

ABSTRACT OF THE THESIS

Numerical Simulation of flow Past NACA 0012 Airfoil Using a Co-Flow Jet at Different Injection Angles to Control Lift and Drag

by

Da Xiao

Master of Science in Mechanical Engineering

Washington University in St. Louis, 2019

Research Advisor: Professor Ramesh K. Agarwal

The focus of this thesis is to numerically study the aerodynamic performance of an airfoil by employing the active flow control from a co-flow jet (CFJ) near the leading edge. The study is conducted by changing the injection angle of CFJ on a location close to the leading edge on the upper surface of ...


Microfluidic Assessment Of Stem Cell-Derived Pancreatic Beta Cells, Arvind Rajamani Srivatsava May 2019

Microfluidic Assessment Of Stem Cell-Derived Pancreatic Beta Cells, Arvind Rajamani Srivatsava

Engineering and Applied Science Theses & Dissertations

Contemporary and traditional methods of perifusional analysis of cells, pancreatic β cells in particular, involve the utilization of costly equipment exhibiting difficulties in setup and inflexibilities in operation and application. Microfluidic devices in general are inexpensive, easy to fabricate and are capable of screening multiple microenvironmental conditions, with the potential to generate concentration gradients for the study of biological phenomena such as cell migration. Utilization of these devices for cellular fluorescence imaging is also possible, paving the way for more sophisticated methods of dynamic assessment. Herein, we fabricated a pre-designed microfluidic device from photolithography, containing microwells capable of immobilizing human ...


Computation Of Flow Fields Due To Single- And Twin-Jet Impingement, Xiang Zhang May 2019

Computation Of Flow Fields Due To Single- And Twin-Jet Impingement, Xiang Zhang

Engineering and Applied Science Theses & Dissertations

The thesis consists of two parts. The first part focuses on numerical simulations and their comparison with experimental data for single-jet impingement on ground. Angles between the axisymmetric jet and impingement surface considered are 15, 30 and 90 degree. It is shown that both the k-epsilon and Wray-Agarwal (WA) model can predict the flow fields in good agreement with the experimental results. The second part extends the first part to twin-jet normal impingement on the ground. It focuses on numerical simulation of fountains formed by the twin-jet impingement. The fountains can be normal straight upward when the two jets are ...


Deformable Image Registration For Hyperspectral Images, Rui Liao May 2019

Deformable Image Registration For Hyperspectral Images, Rui Liao

Engineering and Applied Science Theses & Dissertations

Image registration is one of the basic image processing operations in remote sensing. A hyperspectral image has two spatial dimensions and one spectral dimension. There are many hyperspectral sensors used in remote sensing. Traditional intensity-based registration methods may fail for hyperspectral images because of the different spectral sensitivities for different sensors. In addition, not all spectral bands are required to achieve accurate registration. This thesis develops a modification of the large deformation diffeomorphic metric mappings (LDDMM) algorithm in order to deal with the challenges when applied to hyperspectral images. The transformation generated by our method that deforms one image to ...


Sufficient Conditions For Optimal Control Problems With Terminal Constraints And Free Terminal Times With Applications To Aerospace, Sankalp Kishan Bhan May 2019

Sufficient Conditions For Optimal Control Problems With Terminal Constraints And Free Terminal Times With Applications To Aerospace, Sankalp Kishan Bhan

Engineering and Applied Science Theses & Dissertations

Motivated by the flight control problem of designing control laws for a Ground Collision Avoidance System (GCAS), this thesis formulates sufficient conditions for a strong local minimum for a terminally constrained optimal control problem with a free-terminal time. The conditions develop within the framework of a construction of a field of extremals by means of the method of characteristics, a procedure for the solution of first-order linear partial differential equations, but modified to apply to the Hamilton-Jacobi-Bellman equation of optimal control. Additionally, the thesis constructs these sufficient conditions for optimality with a mathematically rigorous development. The proof uses an approach ...


Modeling Mechanisms Behind Force Generation By Actin Polymerization, Seyed Fowad Motahari May 2019

Modeling Mechanisms Behind Force Generation By Actin Polymerization, Seyed Fowad Motahari

Arts & Sciences Electronic Theses and Dissertations

Actin polymerization is the primary mechanism for overcoming the large turgor pressure that opposes endocytosis in yeast. While generation of pushing forces by actin polymerization is fairly well understood, it is not clear how actin polymerization produces pulling forces. In order to understand this process, it is necessary to simulate polymerization of filaments having various types of interactions with the membrane. Since existing methodologies in the literature do not treat such problems correctly, we develop a thermodynamically consistent methodology for treating polymerization of filaments having arbitrary interaction potentials with the membrane. Then I perform stochastic simulations for a system of ...


Isotopically-Resolved Neutron Cross Sections As Probe Of The Nuclear Optical Potential, Cole Davis Pruitt May 2019

Isotopically-Resolved Neutron Cross Sections As Probe Of The Nuclear Optical Potential, Cole Davis Pruitt

Arts & Sciences Electronic Theses and Dissertations

Neutron scattering experiments provide direct access to the forces experienced by nucleons in the nuclear environment. Due to the experimental difficulty of cross section measurements with neutrons, isotopically-resolved neutron scattering cross sections are sorely needed as inputs for many nuclear models. This dissertation presents the results from a campaign of isotope-specific neutron total cross section measurements on 16,18O, 58,64Ni, 112,124Sn, and 103Rh from 3-450 MeV and elastic scattering differential cross section measurements on 112,nat,124Sn at 11 and 17 MeV. Equipped with these new data and with computational improvements to the Dispersive Optical Model (DOM), we ...


Electronic Transport Behavior Of Adatom- And Nanoparticle-Decorated Graphene, Jamie Anne Elias May 2019

Electronic Transport Behavior Of Adatom- And Nanoparticle-Decorated Graphene, Jamie Anne Elias

Arts & Sciences Electronic Theses and Dissertations

To induce a non-negligible spin-orbit coupling in monolayer graphene, for the purposes of realizing the Kane-Mele Hamiltonian, transition metal adatoms have been deposited in dilute amounts by thermal evaporation in situ while holding the device temperature near 4K. Electronic transport studies including measurements such as gate voltage dependent conductivity and mobility, weak localization, high field magnetoresistance (Shubnikov de Haas oscillations), quantum Hall, and nonlocal voltage were performed at low temperature before and after sequential evaporations. Studies of tungsten adatoms are consistent with literature regarding other metal adatoms on graphene but were unsuccessful in producing a spin-orbit signature, at least partially ...


A High-Throughput Screening Platform For In Vitro Elastic Fiber Production And The Mass Transport Properties Of The Elastic Fiber Compromised Arterial Wall, Austin John Cocciolone May 2019

A High-Throughput Screening Platform For In Vitro Elastic Fiber Production And The Mass Transport Properties Of The Elastic Fiber Compromised Arterial Wall, Austin John Cocciolone

Engineering and Applied Science Theses & Dissertations

Elastin comprises nearly 50% of the wall in large elastic arteries and has a broad variety of physiological roles. As a structural extracellular matrix protein, elastin is responsible for the reversible elasticity in large arties that dampens pulsatile flow and ultimately reduces the workload on the heart. Structural compromise to the elastic fiber network is apparent in the elastin genetic disorders, supravalvular aortic stenosis and autosomal dominant cutis laxa-1, and acquired elastin disorders including hypertension, atherosclerosis, artery calcification, aneurysms, diabetes, and obesity. All of these disorders lead to an increased incidence of cardiovascular related death and the compromised elastic fiber ...


Coupled Correlates Of Attention And Consciousness, Ravi Varkki Chacko May 2019

Coupled Correlates Of Attention And Consciousness, Ravi Varkki Chacko

Engineering and Applied Science Theses & Dissertations

Introduction: Brain Computer Interfaces (BCIs) have been shown to restore lost motor function that occurs in stroke using electrophysiological signals. However, little evidence exists for the use of BCIs to restore non-motor stroke deficits, such as the attention deficits seen in hemineglect. Attention is a cognitive function that selects objects or ideas for further neural processing, presumably to facilitate optimal behavior. Developing BCIs for attention is different from developing motor BCIs because attention networks in the brain are more distributed and associative than motor networks. For example, hemineglect patients have reduced levels of arousal, which exacerbates their attentional deficits. More ...


Management And Security Of Multi-Cloud Applications, Lav Gupta May 2019

Management And Security Of Multi-Cloud Applications, Lav Gupta

Engineering and Applied Science Theses & Dissertations

Single cloud management platform technology has reached maturity and is quite successful in information technology applications. Enterprises and application service providers are increasingly adopting a multi-cloud strategy to reduce the risk of cloud service provider lock-in and cloud blackouts and, at the same time, get the benefits like competitive pricing, the flexibility of resource provisioning and better points of presence. Another class of applications that are getting cloud service providers increasingly interested in is the carriers' virtualized network services. However, virtualized carrier services require high levels of availability and performance and impose stringent requirements on cloud services. They necessitate the ...


Recent Advances In Low-Cost Particulate Matter Sensor: Calibration And Application, Jiayu Li May 2019

Recent Advances In Low-Cost Particulate Matter Sensor: Calibration And Application, Jiayu Li

Engineering and Applied Science Theses & Dissertations

Particulate matter (PM) has been monitored routinely due to its negative effects on human health and atmospheric visibility. Standard gravimetric measurements and current commercial instruments for field measurements are still expensive and laborious. The high cost of conventional instruments typically limits the number of monitoring sites, which in turn undermines the accuracy of real-time mapping of sources and hotspots of air pollutants with insufficient spatial resolution. The new trends of PM concentration measurement are personalized portable devices for individual customers and networking of large quantity sensors to meet the demand of Big Data. Therefore, low-cost PM sensors have been studied ...


Defect Chemistry And Ion Intercalation During The Growth And Solid-State Transformation Of Metal Halide Nanocrystals, Bo Yin May 2019

Defect Chemistry And Ion Intercalation During The Growth And Solid-State Transformation Of Metal Halide Nanocrystals, Bo Yin

Engineering and Applied Science Theses & Dissertations

Abstract of the Dissertation

Defect Chemistry and Ion Intercalation During the Growth and Solid-State Transformation of Metal Halide Nanocrystals

Semiconductor metal halides as light-sensitive materials have applications in multiple areas, such as photographic film, antibacterial agents and photocatalysts. One focus of this dissertation is to achieve novel morphologies of ternary silver bromoiodide (AgBr1-xIx, 0

For the silver halide system, we demonstrate that the anion composition of AgBr1-xIx nanocrystals determines their shape through the introduction of twin defects as the nanocrystals are made more iodide-rich. AgBr1-xIx nanocrystals grow as single-phase, solid solutions with the rock salt crystal structure for anions compositions ...


Improved Orthopaedic Repairs Through Mechanically Optimized, Adhesive Biomaterials, Stephen Wheeler Linderman May 2019

Improved Orthopaedic Repairs Through Mechanically Optimized, Adhesive Biomaterials, Stephen Wheeler Linderman

Engineering and Applied Science Theses & Dissertations

Despite countless surgical advances over the last several decades refining surgical approaches, repair techniques, and tools to treat tendon and tendon-to-bone injuries, we are still left with repair solutions that rely on fairly crude underlying mechanical principles. Musculoskeletal soft tissues have evolved to transfer high loads by optimizing stress distribution profiles across the tissue at each length scale. However, instead of mimicking these natural load transfer mechanisms, conventional suture approaches are limited by high load transfer across only a small number of anchor points within tissue. This leads to stress concentrations at anchor points that often cause repair failure as ...


Fracture Toughness Improvement Of ����� Ceramics By Grain Size Control And Ductile Phase Reinforcement, Kesong Wang May 2019

Fracture Toughness Improvement Of ����� Ceramics By Grain Size Control And Ductile Phase Reinforcement, Kesong Wang

Engineering and Applied Science Theses & Dissertations

This study used grain size control and ductile phase reinforcement to improve fracture toughness of ����� ceramics. Alpha alumina particles of 100 nm, 0.5-1 micrometers, and 10 micrometers were coated with 1-5 nm nickel by electroless nickel plating (ENP). The coated powders were consolidated at 1200℃-1500℃ by spark plasma sintering (SPS). The sintered samples were annealed at 1100 oC for 1.5 hours and 10 hours to determine the effect of post sintering annealing on hardness and fracture toughness. Density of the samples were measured by the standard Archimedes method using a 5 mL pycnometer. Hardness values were determined ...


Differential Estimation Of Audiograms Using Gaussian Process Active Model Selection, Trevor Larsen May 2019

Differential Estimation Of Audiograms Using Gaussian Process Active Model Selection, Trevor Larsen

Engineering and Applied Science Theses & Dissertations

Classical methods for psychometric function estimation either require excessive resources to perform, as in the method of constants, or produce only a low resolution approximation of the target psychometric function, as in adaptive staircase or up-down procedures. This thesis makes two primary contributions to the estimation of the audiogram, a clinically relevant psychometric function estimated by querying a patient’s for audibility of a collection of tones. First, it covers the implementation of a Gaussian process model for learning an audiogram using another audiogram as a prior belief to speed up the learning procedure. Second, it implements a use case ...


Development Of A One-Equation Turbulence Model Based On K-Ε Closure And Its Extension For Computing Transitional Flows By Including An Intermittency Transport Equation, Cheng Peng May 2019

Development Of A One-Equation Turbulence Model Based On K-Ε Closure And Its Extension For Computing Transitional Flows By Including An Intermittency Transport Equation, Cheng Peng

Engineering and Applied Science Theses & Dissertations

No abstract provided.


Research Of Electro-Optical Effect In Metal Halide Perovskites By Fabry-Perot Interometer Method, Hanxiang Yin May 2019

Research Of Electro-Optical Effect In Metal Halide Perovskites By Fabry-Perot Interometer Method, Hanxiang Yin

Engineering and Applied Science Theses & Dissertations

Perovskites have been investigated a lot by present and reported with outstanding optoelectronic properties. However, so far there is no publications about another important property, the electro-optical (EO) effect which is related to important applications in photolithography. This thesis is mainly mean to calculate the EO constants of one kind of organic perovskite material, CH3NH3PbI3, which has been reported to have good capability of forming film by spin-coating, through the way of putting the film of CH3NH3PbI3 between two layers of metal mirrors to build a Fabry-Perot interferometer and characterizing ...


The Effect Of Mechanical Agitator Geometry On Catheter Directed Thrombectomy, Sanghun Alex Lee Apr 2019

The Effect Of Mechanical Agitator Geometry On Catheter Directed Thrombectomy, Sanghun Alex Lee

Engineering and Applied Science Theses & Dissertations

Venous thromboembolism (VTE) is a vascular disease in which a blood clot forms inside of a vein, most often deep in the legs, groin, or arm. Two types of VTE exist, deep vein thrombosis (DVT) and pulmonary embolism (PE). DVT occurs when a clot in a deep vein forms, risking embolism and causing swelling as the clot obstructs blood flow. An embolism occurs when a part or all the thrombus breaks off and travels in the circulation, getting lodged in the lungs. A pulmonary embolism is a very serious medical condition and can be fatal if not treated immediately. Current ...


Understanding Homework Reviews Through Sentiment Classification, Zachary Mekus Apr 2019

Understanding Homework Reviews Through Sentiment Classification, Zachary Mekus

Engineering and Applied Science Theses & Dissertations

This thesis uses a naive bayes sentiment classifier to analyze six semesters of homework review data from CSE427S. Experiments describe the benefits of an automated classification system and explore original ways of reducing the number of features and reviews. A new algorithm is proposed that tries to take advantage of aspects of the review data that limit classification accuracy. This analysis can be used to help guide the process of automatically using short reviews to understand student sentiment.