Engineering Commons^™

The Scaffolds To Guide Fast Angiogenesis, Tianhong Zhou

McKelvey School of Engineering Theses & Dissertations

Angiogenesis is one of the most challenging problems in bone structure repair. The different types of 3D fibrous morphology structure of the extracellular matrix for fasting angiogenesis have been studied. Due to the densely packed constructs and limited porosity of scaffold, the challenge still remains for scaffold fabrication. In this study, we fabricated PCL scaffold with growth factors and cells to guide fast angiogenesis by electro-spinning and electro-spray simultaneously. We developed a technique that electro-spinning encapsulates growth factors OPN(Recombinant Human Osteopontin) and SDF-1α(CXCL12) in poly(lactide-co-glycolide) (PLGA) microspheres into PCL 3D structures scaffold fibers. We also developed a new technique to …

Development Of High-Speed Photoacoustic Imaging Technology And Its Applications In Biomedical Research, Yun He

McKelvey School of Engineering Theses & Dissertations

Photoacoustic (PA) tomography (PAT) is a novel imaging modality that combines the fine lateral resolution from optical imaging and the deep penetration from ultrasonic imaging, and provides rich optical-absorption–based images. PAT has been widely used in extracting structural and functional information from both ex vivo tissue samples to in vivo animals and humans with different length scales by imaging various endogenous and exogenous contrasts at the ultraviolet to infrared spectrum. For example, hemoglobin in red blood cells is of particular interest in PAT since it is one of the dominant absorbers in tissue at the visible wavelength.The main focus of …

Asme Design Challenge: The Jenga Stacker, Zachary Lin, Alex Chernauskas, Mitch Dorsey, Alex Remmers

Mechanical Engineering Design Project Class

The 2020 ASME Design Challenge requires teams to build a compact engineering system capable of manufacturing a tower made exclusively from standard-sized sheets of paper. The validation of the design will include testing for manufacturing speed, height of tower, and ability to support a load. Our senior design project focuses on the stacking mechanism and is designed to stack a 4 in x 4 in tower out of prepared 4 in x 1.5 in x 1.75 in paper boxes from the ground up.

Improved Greens Harvester, Sharon Park, Khalil Clark, Millyn Brieschke

Mechanical Engineering Design Project Class

This paper attempts to provide a prototype of the improved greens harvester. Some inconveniences of the users, including not able to cut greens at a constant length, greens getting clogged in between the brush and the basket, and the need to empty the basket a lot of times. This paper describes problem understanding, concept generation, concept selection, concept embodiment, working prototype, and design refinement. Through these analyses and processes, an improved greens harvester solving the inconveniences is designed. The improved greens harvester has a higher greens harvester with wheels that makes using the harvester less troublesome. Band saw is stuck …

Group A: Asme Student Design Challenge, Dakshi Jindal, Ashley Perry, Ben Liao

Mechanical Engineering Design Project Class

This year's student design competition is termed "Building to the Sky." Student teams are required to build a compact engineering system capable of manufacturing a tower made of only standard-sized sheets of paper.

Dynamics And Control In Spiking Neural Networks, Fuqiang Huang

McKelvey School of Engineering Theses & Dissertations

In the brain, neurons (brain cells) produce electrical impulses, or spikes, that are thought to be the substrate of information processing and computation. Through enigmatic processes, these spikes are ultimately decoded into perceptions and actions. The nature of this encoding and decoding is one of the most pervasive questions in theoretical neuroscience. In other words, what are the specific functions enacted by neural circuits, through their biophysics and dynamics? This thesis examines the dynamics of neural networks from the perspective of control theory and engineering. The pivotal concept is that of the normative synthesis of neural circuits, wherein neural dynamics …

Wheelchair Propulsion For Everyday Manual Wheelchair Users: Repetition Training And Machine Learning-Based Monitoring, Pin-Wei Chen

Arts & Sciences Electronic Theses and Dissertations

Upper limb pain and injuries are prevalent among manual wheelchair users and can restrict their participation and daily activities. Due to the high repetition and force in wheelchair propulsion, chronic wheelchair propulsion has been linked to the risk of upper limb pain and injury. Prevention of upper limb pain and injury is a high priority in wheelchair-related research. Decades of research in wheelchair propulsion biomechanics have led to clinical practice guidelines (CPG). Unfortunately, a decade after the publication of the CPG, CPG-recommended propulsion is still uncommon. Hence, for the first aim, a randomized controlled trial pilot study with two groups …

Longitudinal Acoustic Traps: Design, Fabrication, And Evaluation For Biological Applications, Michael Moore Binkley

McKelvey School of Engineering Theses & Dissertations

Acoustofluidics combine ultrasonic actuation with small-volume microfluidic channels to enable precise, contactless object manipulation for a range of applications from serial chemical processing to blood component separation and single-cell analysis. Micron- to millimeter-scale vibrational waves generate reproducible pressure fields within the microfluidic channels and chambers. By exploiting the material property mismatch between a particle (polymeric and silica beads, cells, etc.) and a suspending fluid, the acoustic radiation force is used to move particles toward regions of low (nodes) or high pressure (antinodes). An understanding of these field-particle interactions is applied to design and implement complicated channel architectures for preferential segregation …

Anion Exchange And Bipolar Membranes For Electrochemical Energy Conversion And Storage, Zhongyang Wang

McKelvey School of Engineering Theses & Dissertations

Anion exchange and bipolar membrane fuel cells generate electrical energy directly from chemical fuels and have attracted considerable interests as alternate power sources for large market applications, such as transportation (hydrogen fuel cells) and unmanned vehicles (sodium borohydride fuel cells). Anion exchange membrane (AEM), generally composed of a polymer with covalently tethered ionic groups, is the central component of the fuel cell serving as the electrolyte, conducting hydroxide ions from cathode to anode, where fast ionic conduction is directly related to power output. However, AEMs currently used in fuel cells (H2 fuel cells and sodium borohydride fuel cells) exhibit ion …

Group E: Improved Greens Harvester, Paige Grittner, Paul Harding, Ned Curran, Jennifer Mata

Mechanical Engineering Design Project Class

The Improved Greens Harvester is a project designing an improved machine that will be used to harvest crops by our client, EarthDance Organic Farm School in Ferguson, MO. The goal of our design was to provide a simple, easy-to-use, and easyto-fix machine that would cut and collect baby green leaves as the user walks along the plant bed. We first sought to address issue with the client’s current machine including low cutting accuracy, strain on the user’s body, frequent jamming, and low efficiency. Our initial design was a cart design that included: an oscillating blade for cutting, a rotating rope-shaft …

Three-Dimensional Image Reconstruction In Transcranial Photoacoustic Computed Tomography, Joemini Poudel

McKelvey School of Engineering Theses & Dissertations

Photoacoustic computed tomography (PACT) is an emerging imaging modality that exploitsoptical contrast and ultrasonic detection principles to form images of the photoacousticallyinduced initial pressure distribution within tissue. The PACT reconstruction problemcorresponds to an inverse source problem in which the initial pressure distribution is recoveredfrom measurements of the radiated pressure wavefield. A major challenge in transcranialPACT brain imaging is compensation for aberrations in the measured data due to the presenceof the skull. Ultrasonic waves undergo absorption, scattering and longitudinal-to-shear wavemode conversion as they propagate through the skull. To properly account for these effects, awave-equation-based inversion method should be employed that can …

Rhodococcus Opacus Pd630 Genetic Tool Development To Enable The Conversion Of Biomass, Drew Michael Delorenzo

McKelvey School of Engineering Theses & Dissertations

The discovery of fossil fuels facilitated a new era in human history and allowed many firsts, such as the mass production of goods, the ability to travel and communicate long distances, the formation of population dense cities, and unprecedented improvements in quality of life. Alternative sources of energy and chemicals are needed, however, as hydrocarbon reserves continue to deplete and the effects of burning fossils on the planet become better understood. Lignocellulosic biomass is the most abundant raw material in the world and a viable alternative to petroleum-derived products. The pre-treatment of lignocellulose (e.g., thermocatalytic depolymerization, enzymatic hydrolysis, pyrolysis, etc.) …

Contemporary Problems In Aerosol Aggregation And Gelation, Pai Liu

McKelvey School of Engineering Theses & Dissertations

Aggregation of nanoparticles in aerosols is a fundamental phenomenon with important implications to diverse fields ranging from material synthesis to pollutant control. The past few decades have witnessed extensive research on investigating the structure and growth mechanism of aerosol aggregates with sizes spanning across several orders of magnitude. This dissertation focuses on some contemporary problems that remain unaddressed in this topical area. Aerosol aggregates in sub-micron regimes, which are formed via the irreversible collision and aggregation of solid nanoparticle monomers, are fractal-like in their morphology. A mathematical description of this seemingly random structure dates to the seminal works by Forest …

Group S- Arliss Project, Preston Bailey, Zach Stelwagon, Cal Reynolds, James Hardy

Mechanical Engineering Design Project Class

Our project was the ARLISS competition project, more specifically the second part of the project where the vehicle must survive a drop and drive to a known location over rough desert terrain. We interviewed our professor, Dr. Potter, who had previous experience with the project to understand what was required in our design. The project started with creating concept ideas and deciding on one, which initially was an airplane to avoid designing a landing mechanism and having to drive over rough terrain. However, this design proved to have too many flaws and was scrapped. The new design was a small …

Corrosion-Resistant Non-Carbon Electrocatalyst Supports For Proton Exchange Membrane Fuel Cells, Cheng He

McKelvey School of Engineering Theses & Dissertations

Proton exchange membrane fuel cells (PEMFCs) are a promising portable power source due to their low operating temperature, minimal pollutant generation and fast startup. However, several challenges remain concerning lifetime, reliability, and cost. A critical issue is PEMFC component durability. Platinum supported on high surface area carbon has been one of the most widely used electrocatalysts in PEMFCs. However, carbon corrosion over the course of normal PEMFC operation occurs due to the relatively low standard electrode potential for the carbon dioxide/carbon redox couple (0.207V vs. standard hydrogen electrode). Considering this challenge, it is imperative to identify alternative support materials to …

Kernel Methods For Graph-Structured Data Analysis, Zhen Zhang

McKelvey School of Engineering Theses & Dissertations

Structured data modeled as graphs arise in many application domains, such as computer vision, bioinformatics, and sociology. In this dissertation, we focus on three important topics in graph-structured data analysis: graph comparison, graph embeddings, and graph matching, for all of which we propose effective algorithms by making use of kernel functions and the corresponding reproducing kernel Hilbert spaces.For the first topic, we develop effective graph kernels, named as "RetGK," for quantitatively measuring the similarities between graphs. Graph kernels, which are positive definite functions on graphs, are powerful similarity measures, in the sense that they make various kernel-based learning algorithms, for …

Instrumentation For Dynamic Nuclear Polarization And Application Of Electron Decoupling For Electron Relaxation Measurement, Nicholas Howard Alaniva

Arts & Sciences Electronic Theses and Dissertations

Dynamic nuclear polarization nuclear magnetic resonance (DNP NMR) exploits internal electron spin and nuclear spin interactions to increase sensitivity and uncover valuable information regarding structure and dynamics of a system. To manipulate these interactions, instrumentation is developed to combine high-power microwave and radiofrequency irradiation with the ability to spin samples at the magic angle (MAS) at temperatures from 90 K to 4.2 K. Electron decoupling uses frequency-modulated microwaves to mitigate the electron-nuclear dipolar interaction, improving signal intensity and resolution in DNP NMR experiments. Electron decoupling is combined with short DNP periods to encode electron spin information in polarized nuclear signal. …

The Role Of Multi-Charged Responses: Construction And Application Of A Tandem Differential Mobility Analyzer (Tdma), Christopher Ray Oxford

McKelvey School of Engineering Theses & Dissertations

Atmospheric aerosols impact health outcomes, visibility, and the energy balance of the earth. The atmosphere contains a variety of compounds, and the volatility (phase change enthalpy and vapor pressure) of each compound determines its partitioning between the gas phase and the particle phase. The hygroscopicity (an aerosol’s affinity for water) of an atmospheric aerosol particle is determined by the many compounds present in the particle, and thus, the volatility impacts hygroscopicity. Changes in hygroscopicity alter the fraction of the aerosol deposited in the lungs and the fraction of the aerosol activated into cloud droplets. Thus, understanding the volatility and hygroscopicity …

Molecular Dynamics Studies Of Thin-Film Evaporation: The Effect Of Graphene-Coated Silicon On Water Evaporation Behavior, Rui Zhou

McKelvey School of Engineering Theses & Dissertations

Conventional single-phase air or liquid cooling methods are insufficient to dissipate the high heat flux of next-generation electronic systems. Thin-film evaporation is one of the most promising solutions, because it takes advantage of the large amount of latent heat in the phase change process. It is important to understand the relationship between interfacial thermal resistance, surface wettability, and thin-film evaporation behavior. In this study, non-equilibrium molecular dynamics simulations are used to study mass and heat transfer in thin-film evaporation of water on a silicon substrate, and equilibrium molecular dynamics simulations are used to study the surface wettability by measuring contact …

3d Chocolate Printer Bed Design, Dean Oken, Jacob Margolin, Ben Hartmann, Sam Grossman

Mechanical Engineering Design Project Class

The client wished for a device to gain the interest of young undergraduate students into basic thermal science and fluid dynamics concepts. A 3D printer bed was created from concept to prototype design and paired with chocolate dropper teams to complete the project and accomplish the client's goals.

Enhanced Heat Transfer Performance By Shape Optimization Of A Non-Axisymmetric Droplet Evaporating On A Heated Micropillar, Haotian Wu

McKelvey School of Engineering Theses & Dissertations

Abstract

Enhanced Heat Transfer Performance by Shape Optimization of a Non-axisymmetric Droplet Evaporating on a Heated Micropillar

By

Haotian Wu

Department of Mechanical Engineering and Materials Science

Washington University in St. Louis, 2019

Research Advisor: Professor Damena Agonafer

The stacked multilayer 3D IC structure used in next generation high-powered electronics poses great challenges in dissipating their large heat flux, which causes extreme difficulties for traditional cooling technologies. In response, more advanced two-phase liquid cooling technologies, such as droplet evaporation, which utilizes the latent heat of vaporization to remove excessive heat, have been widely investigated. Compared to traditional single-phase cooling techniques, …

Mems 411 Group L (Fall 2019) - Speedy Seeder Final Report, Michael Morrow, Christopher Nelson, Ross Frame

Mechanical Engineering Design Project Class

The Speedy Seeder or ”SS” is a device designed to decrease the time it takes to fill one seed plot by hand to roughly sixteen percent of the time. The customer of the SS is EarthDance Organic Farms School. EarthDance fills a large number of plots each year by placing a seed in every single compartment which come in three sizes: 32, 72, and 128 compartments per plot. Filling a single plot by hand can take roughly 8 minutes. The SS makes filling a plot much easier and faster, allowing a single plot to be filled in under 75 seconds. …

Ph-Sensitive Oxygen Release Microspheres To Enhance Cell Survival In Ischemic Condition, Zhongting Liu

McKelvey School of Engineering Theses & Dissertations

Ischemic diseases such as myocardial infarction, stroke and limb ischemia are severe cardiovascular diseases with high rate of death and millions of people suffered from these diseases. Under ischemic environment, cells die due to deficient supply of nutrient and oxygen. To regenerate ischemic tissues, stem cell therapy is a promising approach because stem cells can differentiate into cells necessary for the regeneration. However, stem cell therapy has limitations. For example, few cells can survive under harsh ischemic environment. To enhance stem cells survival, implantation of oxygen release microspheres to sustained supply cells with oxygen represents an effective strategy. Previously, our …

Expanding The Palette: Synthesizing Microencapsulated Organic Phase Change Materials In Metallic Matrices For Transient Thermal Applications, Melissa Kate Mccann

McKelvey School of Engineering Theses & Dissertations

As the demand for smaller and faster electronics increases, it becomes increasingly challenging to effectively manage the generated heat without hindering device performance in applications whose thermal profiles are dominated by pulsed thermal loads. Heat propagation in a system can be characterized by steady or transient state heat transfer. In steady state, the temperature at any particular point remains constant after thermal equilibrium is reached. In a transient state, the temperature within a system varies over time. The changing parameters and time dependency associated with a transient regime make heat transfer calculations far more complex than in a steady state. …

T-Shirt Strip Dispenser, Maxwell Dimgba, Syeda Mohsin, Sabrina Nguyen

Mechanical Engineering Design Project Class

There is a massive amount of waste around the textile industry. New garments are constantly being made and old garments are consistently finding themselves in landfills. This project aims to cut down on this waste. Mary Susan RuppertStroescu of the Sam Fox School at Washington University in St. Louis has developed a process to turn old garments into new ones in a practice known as up-cycling. By cutting old garments into half-inch strips, laying and adhering them flat on a sheet of dissolvable paper, and sewing over them in interesting patterns she is able to create extraordinary new designs. This …

Group M: Arliss Canister Vehicle, Greyson Bourgeois, Eleanor Macklin, Romail Dawani, Rachel Sample

Mechanical Engineering Design Project Class

This project is a dicycle designed for the ARLISS Canister Competition. In this competition, the device is loaded into a rocket which is then launched to about 12000 ft before releasing the device. Then it must safely land and autonomously navigate to a predetermined GPS location on the ground. Due to the fact that this is a mechanical engineering design project and the time restrictions of this class, we focused on the physical aspect of the project, such as building a device that can survive the launch and landing and traverse several kilometers through the desert, forgoing the autonomous navigation …

Violin Bow-Hand Prosthetic, Jonathan Smith, Jonathon Azziz, Shawn Pavey

Mechanical Engineering Design Project Class

The violin bow hand prosthetic was designed for a young violin player seeking to upgrade the functionality of his current violin prosthetic device. His current device is rigid, forcing him to play mostly with his shoulder. Since the strength of his wrist was unknown, we designed a prosthetic with enough brace flexibility to enable the user to control the bow motion with his own wrist. We also added an axis of rotation and spring mechanism to supplement this motion and provide him the equivalence of fine finger adjustments. The full design process of the prosthetic is documented in this report, …

Point Cloud Processing With Neural Networks, Stephanie Miller, Jiahao Li

All Computer Science and Engineering Research

In this project, we explore new techniques and architectures for applying deep neural networks when the input is point cloud data. We first consider applying convolutions on regular pixel and voxel grids, using polynomials of point coordinates and Fourier transforms to get a rich feature representation for all points mapped to the same pixel or voxel. We also apply these ideas to generalize the recently proposed "interpolated convolution", by learning continuous-space kernels as a combination of polynomial and Fourier basis kernels. Experiments on the ModelNet40 dataset demonstrate that our methods have superior performance over the baselines in 3D object recognition.

Violin Bow-Hand Prosthetic, Ron Hayes Jr, Kc Cook, Romario Lobban, Muriel Drexler

Mechanical Engineering Design Project Class

The violin bow-hand prosthetic aims to mimic the natural hold and motion of a violinist’s bow-hand. The prosthetic is for a violinist who is missing the majority of their hand, but still has full range of motion in the wrist. Focusing on maintaining a natural playing style greatly influenced the design of the device to be user safe, durable, comfortable, easy to use, inexpensive, and practical. Many of these features were achieved by using 3D printed plastic and foam composites. These materials were selected based on strength and deflection analyses of 3-D simulations performed in SolidWorks and the ease of …

Group N: Fluid Flow Testing Apparatus, Jonathan Fleming, Braden Kerr, Abel Soloman

Mechanical Engineering Design Project Class

A fluid flow testing apparatus was needed to accurately test valves relative to the conditions seen in the factory of a local St. Louis brewery. After concept generation, a rotating track that toggled the valve between open and closed was decided on by the team. Construction of an initial prototype was done over 3 weeks with a total budget of 400 USD. The initial prototype satisfied almost all of the performance goals: capable of cycling 200 times without intervention, 1 paper-towel of leakage at most, and upper reservoir level consistency within 10 percent. To improve the initial prototype, the team …