Engineering Commons^™

Methodology For Analysis Of Stress, Creep, And Fatigue Behavior Of Compliant Mechanisms, Joshua Allen Crews

Doctoral Dissertations

"A methodology is developed for analyzing stress within homogeneous and metallic-reinforced, fixed-free compliant segments and small-length flexural pivots. Boundary conditions related to the inclusion of metallic reinforcing components within a polymer compliant segment are investigated. The analysis method outlined herein relies on key outputs from the pseudo-rigid-body models (PRBMs). A method is presented for the redesign of compliant mechanisms to include metallic reinforcement to reduce stress while maintaining force-deflection behavior. Examples are provided in which a compliant segment is redesigned to include metallic reinforcement by using the stress equations developed from the PRBM. The effect of bonding between the polymer …

Using Wireless Sensors And Networks Program For Chemical Particle Propagation Mapping And Chemical Source Localization, Xiang Gao

Doctoral Dissertations

"Chemical source localization is a challenge for most of researchers. It has extensive applications, such as anti-terrorist military, Gas and oil industry, and environment engineering. This dissertation used wireless sensor and sensor networks to get chemical particle propagation mapping and chemical source localization. First, the chemical particle propagation mapping is built using interpolation and extrapolation methods. The interpolation method get the chemical particle path through the sensors, and the extrapolation method get the chemical particle beyond the sensors. Both of them compose of the mapping in the whole considered area. Second, the algorithm of sensor fusion is proposed. It smooths …

Static And Dynamic Characterization Of Tied Arch Bridges, John Edward Finke

Doctoral Dissertations

"Tied arch bridges have been designed and constructed since the late 19th century. With their open vista owing to minimalist features tied arch bridges continue to appeal the public. Tied arch bridges are both aesthetic and economical alternates to long span bridges holding a place in the hierarchy of major bridges. They fit in a niche between viable and economical plate girder spans and short cable stayed bridge spans. There are several variations of the tied arch with the most common form being those having vertical hangers, stiff tie girders and slender arch ribs. This tied arch variation is examined …

Adaptive Consensus Based Formation Control Of Unmanned Vehicles, Haci Mehmet Guzey

Doctoral Dissertations

"Over the past decade, the control research community has given significant attention to formation control of multiple unmanned vehicles due to a variety of commercial and defense applications. Consensus-based formation control is considered to be more robust and reliable when compared to other formation control methods due to scalability and inherent properties that enable the formation to continue even if one of the vehicles experiences a failure. In contrast to existing methods on formation control where the dynamics of the vehicles are neglected, this dissertation in the form of four papers presents consensus-based formation control of unmanned vehicles-both ground and …

Advancing Microalgae Culturing Via Bubble Dynamics, Mass Transfer, And Dynamic Growth Investigations, Aastha Ojha

Doctoral Dissertations

"The major hindrances to large scale cultivation of microalgae are the problems associated with the design, operation, and scale-up of airlift photobioreactors (PBRs), due to a lack of a comprehensive understanding of the gas-liquid interaction process in real microalgae cultures. Thus, the overall objective of this work is to advance the fundamental understanding of microalgae culturing via gas holdup, bubble dynamics, mass transfer, and dynamic growth investigations.

First, a four-point optical fiber probe technique was employed to study the local gas holdup, and bubble dynamics properties such as bubble passage frequency, chord length and bubble velocity distribution, and interfacial area …

Characterization Of An Integrated Circuit With Respect To Electrostatic Discharge-Induced Soft Failures, Benjamin J. Orr

Doctoral Dissertations

"This research proposal presents a methodology whereby an integrated circuit (IC) can be characterized with respect to soft-failures induced by Electrostatic Discharge (ESD)-like events. This methodology uses an exclusively "black-box" approach to determine the response of an IC in a system-level environment, thereby allowing it to be implemented without intimate knowledge of the DUT IC. Results from this methodology can be referenced during system design to raise awareness of specific vulnerabilities of the core system ICs.

During work on this methodology, several sub topics have been explored and developed in the field of system-level ESD. Sections 2 and 3 introduce …

Analysis And Mitigation Of Wellbore Breakout And Fracturing, Reza Rahimi

Doctoral Dissertations

"Mechanical wellbore integrity problems while drilling are mainly due to wellbore shear failure or tensile failure. To ensure wellbore integrity, breakout and fracture geomechanical analysis is conducted to estimate minimum and maximum drilling fluid densities. Currently, there is no agreement as to which rock failure criterion to use for estimating breakout or fracture criteria to use for analyzing drilling induced fractures. However, when wellbore integrity issues arise while drilling, mitigation strategies can be applied to rectify these problems.

This dissertation analyzes criteria for wellbore breakout and fracturing. Also, mitigation strategies for breakout and fracturing while drilling were experimentally investigated. Thirteen …

Research On Hybrid Manufacturing Using Industrial Robot, Zhiyuan Wang

Doctoral Dissertations

"The applications of using industrial robots in hybrid manufacturing overcome many restrictions of the conventional manufacturing methods, such as small part building size, long building period, and limited material choices. However, some problems such as the uneven distribution of motion accuracy within robot working volume, the acceleration impact of robot under heavy external loads, few methods and facilities for increasing the efficiency of hybrid manufacturing process are still challenging. This dissertation aims to improve the applications of using industrial robot in hybrid manufacturing by addressing following three categories research issues. The first research issue proposed a novel concept view on …

Identifying Shallow Subsurface Stratigraphy And Voids Using Dispersive Characteristics Of Electromagnetic And Surface Waves, Payman Hajiani

Doctoral Dissertations

"This dissertation presents the results of three manuscripts on spectral analysis of electromagnetic and seismic surface waves to detect subsurface stratigraphy and voids. In the first manuscript, a new technique was developed by utilizing spectral analysis of surface waves to detect subsurface openings. This technique applied the concept of group delay to evaluate the effects of subsurface voids on the phase shift domain. Seismic data sets were acquired at different sites where the shape, size, and depth of the void varied. In all surveys, the time delay technique precisely identified the locations of the subsurface openings. The second manuscript presents …

Wetting Kinetics In Forced Spreading, Amer Mohammad Al-Shareef

Doctoral Dissertations

"Under dynamic conditions, the dynamic contact angle (the angle that the liquid makes with the solid) of a liquid on a solid surface varies dramatically with substrate velocity from its equilibrium value. Experimental data of the dynamic contact angles for polydimethylsiloxane (PDMS or silicone oil) under air on a glass substrate coated with teflon, for water under PDMS, for solutions of the polymer polyethylene oxide (PEO) under air, for solutions of PEO under PDMS, were obtained to simulate and understand the systems of brine or brine containing a polymer displacing viscous crude. A variety of solid substrates were used other …

Innovative Techniques For Seismic-Resistant Bridge Columns Under Ground Motion Excitations, Ayman A. Moustafa

Doctoral Dissertations

“This dissertation provides innovative alternative solutions for replacing conventional reinforced concrete columns. The proposed columns displayed enhanced seismic resistance and properties compared to their counterpart conventional columns. Two main techniques were followed and proposed to develop seismic-resistant columns. The first technique utilized rubberized concrete to internally enhance energy dissipation and damping. Materials testing of rubberized concrete with scrap tire replacement of fine aggregates were performed to evaluate its dynamic properties. Shaking table testing of a rubberized concrete column was performed and the behavior was compared to that of the conventional one. The rubberized column showed an increase of 16% in …

Experimental Performance Evaluation And Design Of Schemes For Passive Rfid Network, Shadi Ebrahimi-Asl

Doctoral Dissertations

"Passive Radio Frequency Identification (RFID) is a short range technology for transferring information. The main advantage of passive RFID systems over active communication systems is the battery-less operation at the client sides. However, there are two major challenges that limit the widespread adaptation of passive RFID systems: short communication range and low read rate in dense deployments. This dissertation addresses these issues by studying the root causes and develops solutions for them.

In this dissertation, understanding the backscattering behavior of antennas and also the mutual coupling interactions among them are found to be the root causes of the two above-mentioned …

Integrated Geophysical Approach Using Electrical Resistivity Tomography And Multichannel Analysis Of Surface Wave In Assessing Wilson Spring Development, Ibrahim E. Ahmed

Doctoral Dissertations

"This research investigated fractured zones leading to preferential flow paths of Wilson Spring. In this context, electrical resistivity tomography (ERT) data and multi-channel analyses of surface waves (MASW) data were acquired at studied site with the purpose of mapping a variable depth to top of bedrock and geological structures.

Interpretation of the boreholes, MASW, and ERT data indicated that a depth to top of rock does vary significantly at the studied site due to many solution-widened fractures. Multiple near-vertical solution-widened fractures were mapped in the studied site based on the interpretation of the ERT data. The mapped solution-widened fractures appear …

Repetitive Process Control Of Additive Manufacturing With Application To Laser Metal Deposition, Patrick M. Sammons

Doctoral Dissertations

"Additive Manufacturing (AM) is a set of manufacturing processes which has promise in the production of complex, functional structures that cannot be fabricated with conventional manufacturing and the repair of high-value parts. However, a significant challenge to the adoption of additive manufacturing processes to these applications is proper process control. In order to enable closed-loop process control compact models suitable for control design and for describing the layer-by-layer material addition process are needed. This dissertation proposes a two-dimensional modeling and control framework, with an application to a specific metal-based AM process, whereby the deposition of the current layer is affected …

Composite Confinement Systems For Rc Column Repair And Construction Under Seismic Loads: Concept, Characterization And Performance, Mostafa Fakharifar

Doctoral Dissertations

"This study aims at developing, characterizing and validating an integrated composite confinement system of conventional jackets for: (1) repair and retrofit of existing bridge columns; and (2) construction of new bridge columns, subjected to earthquake excitations.

A new composite steel confinement jacket was proposed by combining a thin steel sheet and prestressing strands as a hybrid jacket, incorporating active and passive confining pressure on damaged RC columns. Both experimental and analytical studies were conducted to understand the performance and effectiveness of the proposed repair method. The experimental study involved two 1/2-scale lap-spliced deficient RC bridge columns originally tested to failure …

Modeling And Evaluation Of Moisture Diffusion In Polymer Composite Materials, Zhen Huo

Doctoral Dissertations

"Fiber-reinforced polymer composites have extensive applications due to their high specific strength, improved product performance, low maintenance and design flexibility. However, moisture absorbed by polymer composites during the service life plays a detrimental role in both the integrity and durability of composite structure. It is essential to understand the moisture diffusion behavior and induced damage in polymer matrix composites under varying hygrothermal conditions. In Part I, the moisture diffusion characteristics in hybrid composites using moisture concentration-dependent diffusion method have been investigated. Also, a multi-stage diffusion model was proposed to explain the deviation of moisture diffusion behavior for sandwich composites from …

Convective Cooling In A Pool-Type Research Reactor, Susan Sipaun, Shoaib Usman

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

A reactor produces heat arising from fission reactions in the nuclear core. In the Missouri University of Science and Technology research reactor (MSTR), this heat is removed by natural convection where the coolant/moderator is demineralised water. Heat energy is transferred from the core into the coolant, and the heated water eventually evaporates from the open pool surface. A secondary cooling system was installed to actively remove excess heat arising from prolonged reactor operations. The nuclear core consists of uranium silicide aluminium dispersion fuel (U₃Si₂Al) in the form of rectangular plates. Gaps between the plates allow coolant …

Processing Of Al-12si-Tnm Composites By Selective Laser Melting And Evaluation Of Compressive And Wear Properties, Konda Prashanth, Sergio Scudino, Anil Chaubey, Lukas Löber, Pei Wang, Hooyar Attar, Frank Schimansky, Florian Pyczak, Jürgen Eckert

Research outputs 2014 to 2021

Al-12Si (80 vol%)-Ti52.4Al42.2Nb4.4Mo0.9B0.06 (at.%) (TNM) composites were successfully produced by the selective laser melting (SLM). Detailed structural and microstructural analysis shows the formation of the Al6MoTi intermetallic phase due to the reaction of the TNM reinforcement with the Al-12Si matrix during SLM. Compression tests reveal that the composites exhibit significantly improved properties (∼140 and ∼160 MPa higher yield and ultimate compressive strengths, respectively) compared with the Al-12Si matrix. However, the samples break at ∼6% total strain under compression, thus showing a reduced plasticity of the composites. Sliding wear tests were carried out for both the Al-12Si matrix and the Al-12Si-TNM …

Ultra-Sustainable Fe78si9b13 Metallic Glass As A Catalyst For Activation Of Persulfate On Methylene Blue Degradation Under Uv-Vis Light, Zhe Jia, Xiaoguang Duan, Wenchang Zhang, Weimin Wang, Hongqi Sun, Shaobin Wang, Laichang Zhang

Research outputs 2014 to 2021

Stability and reusability are important characteristics of advanced catalysts for wastewater treatment. In this work, for the first time, sulfate radicals (SO4∙−) with a high oxidative potential (Eo = 2.5–3.1 V) were successfully activated from persulfate by a Fe78Si9B13 metallic glass. This alloy exhibited a superior surface stability and reusability while activating persulfate as indicated by it being used for 30 times while maintaining an acceptable methylene blue (MB) degradation rate. The produced SiO2 layer on the ribbon surface expanded strongly from the fresh use to the 20th use, providing stable protection of the buried Fe. MB degradation and kinetic …

Structural Geodesic-Tchebychev Transform: An Image Similarity Measure For Face Recognition, Ali Nadhim Razzaq, Zahir Hussain, Hind Rustum Mohammed

Research outputs 2014 to 2021

This work presents a new holistic measure for face recognition. Face recognition involves three steps: Face Detection, Feature Extraction and Matching. In the face detection process to identify the face area in face images, Viola-Jones algorithm has been used. Feature extraction is based on performing double-transformation, where discrete Tchebychev transform is performed on the geodesic distance transform of the grayscale image. Structural Similarity (SSIM) is applied to the resulting image double-transform to find matching factor with other image faces in the FEI (Brazilian) database. Performance is measured using a confidence criterion based on the similarity distance between the recognized person …

Computational Assessment Of Neural Probe And Brain Tissue Interface Under Transient Motion, Michael Polanco, Sebastian Bawab, Hangsoon Yoon

Mechanical & Aerospace Engineering Faculty Publications

The functional longevity of a neural probe is dependent upon its ability to minimize injury risk during the insertion and recording period in vivo, which could be related to motion-related strain between the probe and surrounding tissue. A series of finite element analyses was conducted to study the extent of the strain induced within the brain in an area around a neural probe. This study focuses on the transient behavior of neural probe and brain tissue interface with a viscoelastic model. Different stages of the interface from initial insertion of neural probe to full bonding of the probe by astro-glial …

การพัฒนาแนวทางในการปรับยกระดับระบบบริหารคุณภาพจาก Iso 9001:2008 สู่ Iso 9001:2015, อัครพันธ์ จันทร์เสงี่ยม

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้มีจุดมุ่งหมายเพื่อประยุกต์การบริหารการเปลี่ยนแปลงในการปรับเปลี่ยนระบบบริหารคุณภาพ ISO 9000 ซึ่งปัจจุบันได้มีการปรับเปลี่ยนจากระบบบริหารคุณภาพ ISO 9001:2008 มาเป็นระบบบริหารคุณภาพ ISO 9001:2015 การเปลี่ยนแปลงนี้เป็นการเปลี่ยนแปลงที่เกิดจากภายนอกองค์กร (External Change) โดยองค์กรที่ได้รับการรับรองระบบ ISO หรือองค์กรที่ต้องการต่อใบรับรองต้องดำเนินการให้เหมาะสม งานวิจัยนี้เป็นการประยุกต์ใช้ขั้นตอนเพื่อการบริหารการเปลี่ยนแปลงให้บรรลุเป้าหมาย 8 ประการ ดังนี้ 1) สร้างสำนึกความจำเป็นเร่งด่วนที่ต้องเปลี่ยนแปลง 2) สร้างขุมพลังในการนำการเปลี่ยนแปลง 3) กำหนดวิสัยทัศน์และแผนการเปลี่ยนแปลงเชิงกลยุทธ์ 4) สื่อสารวิสัยทัศน์เพื่อสร้างการสนับสนุน 5) การดำเนินการเพื่อขจัดอุปสรรคของการเปลี่ยนแปลง 6) กำหนดเป้าหมายระยะสั้น และวางแผนเพื่อให้บรรลุเป้าหมาย 7) เสริมแรงการเปลี่ยนแปลงเพื่อการพัฒนาอย่างยั่งยืน 8) ปลูกฝังสิ่งที่เปลี่ยนแปลงให้เป็นส่วนหนึ่งของวัฒนธรรมบริษัท โดยแต่ละขั้นตอนได้นำเอาแนวคิดและทฤษฎีที่เกี่ยวกับการบริหารการเปลี่ยนแปลง เช่น แนวคิดเกี่ยวกับการต้านทานการเปลี่ยนแปลง (Force Field Analysis) การทดสอบความพร้อมในการเปลี่ยนแปลง (TROPICS Test) การศึกษาสภาพแวดล้อมองค์กร การวางแผนกลยุทธ์องค์กร การประเมินความเสี่ยง เป็นต้น มาประยุกต์ใช้เพื่อให้เกิดการเปลี่ยนแปลงได้อย่างมีประสิทธิผล และในงานวิจัยนี้ยังได้นำกระบวนการบริหารการเปลี่ยนแปลงของระบบบริหารคุณภาพนี้ ไปประยุกต์ใช้กับบริษัทกรณีศึกษาบริษัทผลิตโคมไฟ ซึ่งเป็นบริษัทผลิตโคมไฟลำดับแรกๆของประเทศ โดยผลของการประยุกต์ใช้ในครั้งนี้ส่งผลให้สามารถพัฒนากรอบการบริหารการเปลี่ยนแปลงเพื่อปรับเปลี่ยนระบบบริหารคุณภาพได้อย่างมีประสิทธิภาพ

Capturing The Big Picture: The 2015 Capstone Design Survey, Susannah Howe

Engineering: Faculty Publications

No abstract provided.

Controlled Meteorological (Cmet) Free Balloon Profiling Of The Arctic Atmospheric Boundary Layer Around Spitsbergen Compared To Era-Interim And Arctic System Reanalyses, Tjarda J. Roberts, Marina Dütsch, Lars R. Hole, Paul Voss

Engineering: Faculty Publications

Observations from CMET (Controlled Meteo- rological) balloons are analysed to provide insights into tropospheric meteorological conditions (temperature, hu- midity, wind) around Svalbard, European High Arctic. Five Controlled Meteorological (CMET) balloons were launched from Ny-Ålesund in Svalbard (Spitsbergen) over 5–12 May 2011 and measured vertical atmospheric profiles over coastal areas to both the east and west. One notable CMET flight achieved a suite of 18 continuous soundings that probed the Arctic marine boundary layer (ABL) over a period of more than 10 h. Profiles from two CMET flights are compared to model output from ECMWF Era-Interim reanal- ysis (ERA-I) and to …

Phase I Inspection Of The Stay Cable System On The Us 231 William H. Natcher Bridge Over The Ohio River, Theodore Hopwood Ii, Sudhir Palle, Danny Wells, Bobby W. Meade, Jared Fairchild, Christopher Goff

Kentucky Transportation Center Research Report

The US 231 Natcher Bridge was opened in 2002. By 2006 cracking was observed in the plastic piping that protected the stay cable strands from the environment at both the deck and tower anchorages. Over time the extent of cracking increased and an investigation was initiated to assess the types of deterioration impacting the cables, their causes and their impacts on the integrity of the stay cables.

From 2012-2015, a series of in-depth field inspections were performed using visual and nondestructive testing. Most of this work focused on the piping at the deck anchorages. The inspections disclosed voids in cable …

High-Temperature, High-Pressure Viscosities And Densities Of Toluene, Aaron J. Rowane

Theses and Dissertations

High-temperature, high-pressure (HTHP) conditions are exemplified in ultra-deep petroleum reservoirs and can be exhibited within diesel engines. Accurate pure component hydrocarbon data is essential in understanding the overall behavior of petroleum and diesel fuel at these conditions. The present study focuses on the HTHP properties of toluene since this hydrocarbon is frequently used to increase the octane rating of gasoline and toluene occurs naturally in crude oil. In this thesis experimental densities and viscosity are presented to 535 K and 300 MPa extending the database of toluene viscosity data to higher temperature than previous studies. The data is correlated to …

Drying Methods For The Fabrication Of Polymer Foam Material, Dalton Echard

Theses and Dissertations

This is a report on the study of the drying of nanoporous polymer foam material fabricated by photolithogtaphic methods. Three drying methods were employed, which were air drying, supercritical drying and freeze drying. After fabrication and drying, physical properties of the polymer foams were measured. These measurements included density of the material, Young’s modulus, surface area, and the shape of the skeletal particles. The measurements determined the effect of the polymer concentration and the effect of drying methods. It was determined that polymer concentration had a much larger effect on the properties of the materials than the drying method.

Modeling Time-Dependent Performance Of Submerged Superhydrophobic Or Slippery Surfaces, Ahmed A. Hemeda

Theses and Dissertations

The goal of this study is to quantify the transient performance of microfabricated superhydrophobic surfaces when used in underwater applications. A mathematical framework is developed and used to predict the stability, longevity, and drag reduction benefits of submerged superhydrophobic surfaces with two- or three-dimensional micro-textures. In addition, a novel design is proposed to improve the drag-reduction benefits of lubricant-infused surfaces, by placing a layer of trapped air underneath the lubricant layer. The new design is referred to as lubricant–infused surfaces with trapped air, and it is designed to eliminate the long-lasting longevity problem of submerged superhydrophobic surfaces. The effectiveness of …

Hpc Enabled Data Analytics For High-Throughput High-Content Cellular Analysis, Ross A. Smith, Rhonda J. Vickery, Jack Harris, Sara Gharabaghi, Thomas Wischgoll, David Short, Robert Trevino, Steven A. Kawamoto, Thomas J. Lamkin, Kevin Schoen, Eric E. Bardes, Scott C. Tabar, Bruce J. Aronow

Computer Science and Engineering Faculty Publications

Biologists doing high-throughput high-content cellular analysis are generally not computer scientists or high performance computing (HPC) experts, and they want their workflow to support their science without having to be. We describe a new HPC enabled data analytics workflow with a web interface, HPC pipeline for analysis, and both traditional and new analytics tools to help them transition from a single workstation mode of operation to power HPC users. This allows the processing of multiple plates over a short period of time to ensure timely query and analysis to match potential countermeasures to individual responses.

An Efficient Hybrid Eye Detection Method, Mingxin Yu, Yingzi Lin, Xiangzhou Wang

Turkish Journal of Electrical Engineering and Computer Sciences

Eye detection is the most important and critical task of diverse applications such as face detection and recognition. However, most eye detection methods do not fully consider detection robustness to people with glasses, illumination variation, head pose change, and eye occlusions. This paper proposes an efficient hybrid eye detection method based on a gray intensity variance filter (VF) and support vector machines (SVMs). Firstly, the VF is used for eliminating most of noneye region images to keep less candidate eye regions. Then accurate two eye regions are determined easily through the trained SVM classifier. Moreover, this paper provides an assessment …