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Articles 62341 - 62370 of 198169

Full-Text Articles in Engineering

การประเมินประสิทธิภาพของการผลิตไอน้ำจากการลดความชื้นของชานอ้อย กรณีศึกษาโรงไฟฟ้าชีวมวล, กมล เฟื่องเจริญ Jan 2020

การประเมินประสิทธิภาพของการผลิตไอน้ำจากการลดความชื้นของชานอ้อย กรณีศึกษาโรงไฟฟ้าชีวมวล, กมล เฟื่องเจริญ

Chulalongkorn University Theses and Dissertations (Chula ETD)

ในโรงงานผลิตน้ำตาลจะมีของเสียเป็นชานอ้อยหลังจากการผลิตน้ำตาล ชานอ้อยสามารถนำมาใช้เป็นเชื้อเพลิงในการผลิตไฟฟ้าได้ และเป็นที่ทราบกันดีว่าชานอ้อยที่ได้มาจากการผลิตน้ำตาลนั้นมีความชื้นสะสมไว้มาก ทำให้ประสิทธิภาพในการให้ความร้อนลดลง จุดประสงค์ของการศึกษานี้เพื่อประเมินประสิทธิภาพของหม้อไอน้ำหลังจากลดความชื้นของชานอ้อย โดยใช้เครื่องอบชานอ้อยแบบสายพาน ประสิทธิภาพของหม้อไอน้ำคำนวณโดยใช้วิธีแบบทางอ้อม เมื่อลดความชื้นของเชื้อเพลิงชานอ้อยลงจากร้อยละ 51.3 เหลือร้อยละ 37.2 ประสิทธิภาพของหม้อไอน้ำจะเพิ่มขึ้นร้อยละ 5.7

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การประเมินศักยภาพเชิงพื้นที่ของแผงพลังงานแสงอาทิตย์ชนิดติดตั้งบนหลังคา กรณีศึกษา เขตพื้นที่จุฬาลงกรณ์มหาวิทยาลัย, บุญยนุช กรีกูล Jan 2020

การประเมินศักยภาพเชิงพื้นที่ของแผงพลังงานแสงอาทิตย์ชนิดติดตั้งบนหลังคา กรณีศึกษา เขตพื้นที่จุฬาลงกรณ์มหาวิทยาลัย, บุญยนุช กรีกูล

Chulalongkorn University Theses and Dissertations (Chula ETD)

สารนิพนธ์นี้นำเสนอการศึกษาและประเมินศักยภาพเชิงพื้นที่ของแผงเซลล์แสงอาทิตย์ชนิดติดตั้งบนหลังคา กรณีศึกษา เขตพื้นที่จุฬาลงกรณ์มหาวิทยาลัย มีวัตถุประสงค์เพื่อศึกษาเกี่ยวกับระบบผลิตไฟฟ้าพลังงานแสงอาทิตย์ชนิดติดตั้งบนหลังคา ข้อกำหนดและข้อจำกัดต่าง ๆ นำมาใช้เป็นเกณฑ์ในการคัดเลือกเพื่อใช้ในการประเมินพื้นที่ที่สามารถติดตั้งแผงเซลล์แสงอาทิตย์บนหลังคาและประเมินพลังงานไฟฟ้าที่ผลิตได้จากพื้นที่ดังกล่าว จากการรวบรวมข้อมูลมีจำนวนอาคารรวม 216 อาคาร และใช้ข้อจำกัดด้านวิศวกรรมในการคัดเลือกพื้นที่หลังคาอาคาร มีอาคารจำนวน 87 อาคารที่ผ่านการคัดเลือก จากการคำนวณพลังงานไฟฟ้าที่ผลิตได้และการใช้โปรแกรมวิเคราะห์ จากการศึกษาสามารถสรุปได้ว่าพื้นที่หลังคาอาคารที่เหมาะสมสำหรับการติดตั้งระบบผลิตไฟฟ้าพลังงานแสงอาทิตย์มีทั้งหมดประมาณ 113,897 ตารางเมตร และโดยเมื่อประเมินพื้นที่สำหรับการติดตั้งจริงโดยคำนึงถึงสิ่งกีดขวาง เช่น ระบบปรับอากาศขนาดใหญ่ เป็นต้น และการจัดวางแผงและระบบทำให้มีพื้นที่ที่สามารถติดตั้งได้จริงเพียงร้อยละ 40 มีความสามารถในการติดตั้งแผงเซลล์แสงอาทิตย์ได้สูงสุดจำนวน 23,076 แผง หรือคิดเป็นพื้นที่ 46,590.44 ตารางเมตร โดยมีพลังงานไฟฟ้าที่ประเมินว่าจะผลิตได้ทั้งหมด 13,473.03 MWh/year ทั้งนี้พลังงานไฟฟ้าที่ผลิตได้คิดเป็นสัดส่วนการทดแทนการใช้พลังงานได้ร้อยละ 26.49 ของการใช้ไฟฟ้าทั้งหมดในมหาวิทยาลัย คิดเป็นค่าไฟประมาณปีละ 66,556,768.2 บาท

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Improvement Of Zno Doping Properties Via Sputtering Process With Gas-Timing Technique, Nattaya Tajina Yossapong Jan 2020

Improvement Of Zno Doping Properties Via Sputtering Process With Gas-Timing Technique, Nattaya Tajina Yossapong

Chulalongkorn University Theses and Dissertations (Chula ETD)

In order to obtain high quality of ZnO thin film on plastic and glass substrate for applying to the production of flexible devices, ZnO thin film was investigated by using LP-ZnO buffer layer and gas-timing technique with RF magnetron sputtering at low or room temperature without heat treatment. Growing ZnO thin film directly on plastic substrate without buffer layer, the result was cracking, cavity and wrinkling film. The first part, the effect of buffer layer was studied by growing homo-buffer layer with low-power on plastic substrate and growing main film with high-power on top of that layer calling 2 step …

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A Comparative Analysis Of Reinforcement Learning Applied To Task-Space Reaching With A Robotic Manipulator With And Without Gravity Compensation, Jonathan Fugal Jan 2020

A Comparative Analysis Of Reinforcement Learning Applied To Task-Space Reaching With A Robotic Manipulator With And Without Gravity Compensation, Jonathan Fugal

Theses and Dissertations--Electrical and Computer Engineering

Advances in computing power in recent years have facilitated developments in autonomous robotic systems. These robotic systems can be used in prosthetic limbs, wearhouse packaging and sorting, assembly line production, as well as many other applications. Designing these autonomous systems typically requires robotic system and world models (for classical control based strategies) or time consuming and computationally expensive training (for learning based strategies). Often these requirements are difficult to fulfill. There are ways to combine classical control and learning based strategies that can mitigate both requirements. One of these ways is to use a gravity compensated torque control with reinforcement …

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Performance Enhancement And Prediction Of Composite Materials With Embedded Electrospun Piezoelectric Sensors, Rahman Jani Mazed, Muthu Ram Prabhu Elenchezhian, Vamsee Vadlamudi, Md Riaz Uddin Ahmed, Rassel Raihan, Kenneth Reifsnider Jan 2020

Performance Enhancement And Prediction Of Composite Materials With Embedded Electrospun Piezoelectric Sensors, Rahman Jani Mazed, Muthu Ram Prabhu Elenchezhian, Vamsee Vadlamudi, Md Riaz Uddin Ahmed, Rassel Raihan, Kenneth Reifsnider

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

In today’s world, continuous fiber reinforced composite materials are extensively used in the aerospace, automotive and other structural industries. Since the applications of such fibers demand for a high safety rating, it is of utmost importance for engineers who design such materials to analyze its safety. When cracks are developed in such materials, the mechanical, electrical, and thermal properties also get altered as a function of the cracks. Previous studies have shown that changes in electrical properties can be directly correlated with the development of cracks in the material which can then be used to predict the remaining life of …

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Stel Benchmark Verb Alignment To Cognitive, Affective, And Psychomotor Domains, T. Shown, Philip A. Reed Jan 2020

Stel Benchmark Verb Alignment To Cognitive, Affective, And Psychomotor Domains, T. Shown, Philip A. Reed

STEMPS Faculty Publications

(First paragraph) Curriculum developers and classroom teachers often need to make sure they are teaching and assessing students at the appropriate levels of the cognitive, affective, and psychomotor domains. The STEL benchmarks are written with active verbs to target different levels of these domains. In addition, curriculum developers and classroom teachers want to know whether the benchmarks are at the factual, conceptual, procedural, or metacognitive level of knowledge. The second resource being provided on ITEEA’s interactive STEL website will identify these factors for all 142 STEL benchmarks. This tool was developed to help insure the alignment of the three domains …

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Logistic Function Based Nonlinear Modeling And Circuit Analysis Of The Bipolar Vacancy Migration Memristor, Isaac P. Abraham Jan 2020

Logistic Function Based Nonlinear Modeling And Circuit Analysis Of The Bipolar Vacancy Migration Memristor, Isaac P. Abraham

Browse all Theses and Dissertations

Memristor is an acronym for memory resistor. Memristors promise to be building blocks for high density memory and analog computation. Hewlett Packard’s announcement in 2008 of having fabricated a memristor on an integrated circuit scale has created a tangible excitement in this field. Understanding and exploiting the full potential of these devices requires good compact models. Symbolic modeling provides a balance between achieving accurate empirical fit and generating closed form expressions. This dissertation simplifies the transport equation into a variable coefficient advection equation, very similar to a Burgers’ equation traditionally used in fluid dynamics. The Burgers’-like model reveals the dual …

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Joint Shelf Design And Shelf Space Allocation Problem For Retailers, Hakan Gecili Jan 2020

Joint Shelf Design And Shelf Space Allocation Problem For Retailers, Hakan Gecili

Browse all Theses and Dissertations

Although the retail business has been exploring innovative ways to engage shoppers, the COVID-19 pandemic has sped up their effort. Because of its unique benefits, physical stores will continue to remain an integral part of the overall retail business. However, to stay competitive, retailers will be forced to effectively utilize their available space in physical store (and even reduce it if need be), while offering a reasonably large assortment of products on their shelves. For many such retailers, the design of planograms – visual representation of products on shelves – is still driven by prior experience and intuition. Further, existing …

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Topological Analysis Of Averaged Sentence Embeddings, Wesley J. Holmes Jan 2020

Topological Analysis Of Averaged Sentence Embeddings, Wesley J. Holmes

Browse all Theses and Dissertations

Sentence embeddings are frequently generated by using complex, pretrained models that were trained on a very general corpus of data. This thesis explores a potential alternative method for generating high-quality sentence embeddings for highly specialized corpora in an efficient manner. A framework for visualizing and analyzing sentence embeddings is developed to help assess the quality of sentence embeddings for a highly specialized corpus of documents related to the 2019 coronavirus epidemic. A Topological Data Analysis (TDA) technique is explored as an alternative method for grouping embeddings for document clustering and topic modeling tasks and is compared to a simple clustering …

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Design Of A Novel Wearable Ultrasound Vest For Autonomous Monitoring Of The Heart Using Machine Learning, Garrett G. Goodman Jan 2020

Design Of A Novel Wearable Ultrasound Vest For Autonomous Monitoring Of The Heart Using Machine Learning, Garrett G. Goodman

Browse all Theses and Dissertations

As the population of older individuals increases worldwide, the number of people with cardiovascular issues and diseases is also increasing. The rate at which individuals in the United States of America and worldwide that succumb to Cardiovascular Disease (CVD) is rising as well. Approximately 2,303 Americans die to some form of CVD per day according to the American Heart Association. Furthermore, the Center for Disease Control and Prevention states that 647,000 Americans die yearly due to some form of CVD, which equates to one person every 37 seconds. Finally, the World Health Organization reports that the number one cause of …

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A First Principles Study Of Pipe Diffusion In Nickel, Luke J. Wirth Jan 2020

A First Principles Study Of Pipe Diffusion In Nickel, Luke J. Wirth

Browse all Theses and Dissertations

Vacancy-mediated diffusion along dislocations, often referred to as pipe diffusion, can contribute to creep deformation of metals in many engineering applications. This process is studied along an a/2⟨1 -1 0⟩ screw dislocation in fcc Ni using a density functional theory approach. An accurate geometrical configuration of the screw dislocation core, dissociated into Shockley partial dislocations and separated by a stacking fault, was previously derived using a lattice Green's function technique. Activation energies and frequencies are calculated for atom-vacancy exchanges that contribute to diffusion around and along one of the partial cores. This analysis reveals the significant role of the sites …

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The Steady-State Analysis Of The Non-Isolated And Isolated Type Sepic Pwm Dc-Dc Converters For Ccm, Anuroop Reddy Dasari Jan 2020

The Steady-State Analysis Of The Non-Isolated And Isolated Type Sepic Pwm Dc-Dc Converters For Ccm, Anuroop Reddy Dasari

Browse all Theses and Dissertations

The purpose of this thesis is to develop the theory for analysing and designing the non-isolated and isolated type of SEPIC converters for continuous conduction mode (CCM). The non-isolated converter has single output. The isolated converter considered has two cases: single output and multi-output. The principle of operation of each circuit is explained during different time intervals of the switching cycle. The analytical expressions for various characteristics of the circuits are derived, such as: MV DC and MIDC of the lossless and lossy converter; average and peak-to-peak currents through the inductors, primary and secondary windings of the transformer; average and …

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Understanding Depression During The Covid-19 Pandemic Through Social Media Data, Nusrat Armin Jan 2020

Understanding Depression During The Covid-19 Pandemic Through Social Media Data, Nusrat Armin

Electronic Theses and Dissertations

The COVID-19 pandemic has dramatically affected peoples’ daily lives all over theworld - physically, economically, and emotionally. Due to the virus, many people have died, and many hospitalized. A record number of people have lost their job, and many businesses have closed. The global economy is at risk. People are facing new realities of their lives. Studies have shown that the level of depression is three times higher than before this pandemic. Previous studies have shown that people use social media to express their emotions and feelings. The purpose of this study is to understand the depression during this COVID-19 …

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Tunable-Focus Liquid Lens Through Charge Injection, Shizhi Qian, Wenxiang Shi, Huai Zheng, Zhaohui Liu Jan 2020

Tunable-Focus Liquid Lens Through Charge Injection, Shizhi Qian, Wenxiang Shi, Huai Zheng, Zhaohui Liu

Mechanical & Aerospace Engineering Faculty Publications

Liquid lenses are the simplest and cheapest optical lenses, and various studies have been conducted to develop tunable-focus liquid lenses. In this study, a simple and easily implemented method for achieving tunable-focus liquid lenses was proposed and experimentally validated. In this method, charges induced by a corona discharge in the air were injected into dielectric liquid, resulting in “electropressure” at the interface between the air and the liquid. Through a 3D-printed U-tube structure, a tunable-focus liquid lens was fabricated and tested. Depending on the voltage, the focus of the liquid lens can be adjusted in large ranges (−∞ to −9 …

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Assessment And Applications Of The Conversion Of Chemical Energy To Mechanical Energy Using Model Rocket Engines, Hüseyin Sarper, Nebojsa I. Jaksic, Ben J. Stuart, Karina Arcaute Jan 2020

Assessment And Applications Of The Conversion Of Chemical Energy To Mechanical Energy Using Model Rocket Engines, Hüseyin Sarper, Nebojsa I. Jaksic, Ben J. Stuart, Karina Arcaute

Mechanical & Aerospace Engineering Faculty Publications

To provide the first-year engineering students with a hands-on experience in an engineering application using both chemistry and physics, this team project uses a set of chemical and physical energy concepts and MS Excel based analysis. The main objective of the project is to calculate how much of the potential maximum possible chemical energy is converted into propulsion when using model rocket engines with solid fuel. The secondary objective is to determine the effects of increasing conversion rates on the performance of a model rocket. The solid fuel or propellant used in common model rocket engines is black powder. Compared …

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Defects Analysis Of Seat Belt Tensioner Cast Body, Artur Soroczński, Piotr Czyżewski, Krzysztof Rechowicz Jan 2020

Defects Analysis Of Seat Belt Tensioner Cast Body, Artur Soroczński, Piotr Czyżewski, Krzysztof Rechowicz

VMASC Publications

The article presents an analysis of the implementation of a selected element of the traveler safety system used in road transport. The results of metallographic tests were presented, and the state of stress introduced to the casting by means of forming the element by means of plastic forming was analyzed. An analysis of the manufacturing process was carried out indicating the risks that may lead to cracks in the material structure. Possible causes of founding defects were pointed out and possible technological solutions were pointed out in order to avoid them.

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Arsenic Exposure And Methylation Efficiency In Relation To Oxidative Stress In Semiconductor Workers, Chih-Hong Pan, Ching-Yu Lin, Ching-Huang Lai, Hueiwang Anna Jeng Jan 2020

Arsenic Exposure And Methylation Efficiency In Relation To Oxidative Stress In Semiconductor Workers, Chih-Hong Pan, Ching-Yu Lin, Ching-Huang Lai, Hueiwang Anna Jeng

Community & Environmental Health Faculty Publications

This study examined associations between oxidative stress and arsenic (As) exposure and methylation efficiency in semiconductor workers. An As-exposed group (n = 427) and a control group (n = 91) were included. The As-exposure group (n = 427) included 149 maintenance staff members and 278 production staff members representing high As exposure and low As exposure, respectively. The control group included 91 administrative staff members with no or minimal As exposure. An occupational exposure assessment was conducted to assess personal As exposure by measuring As concentrations in urine, hair, and fingernails of the subjects. Urinary As(III), As(V), monomethylarsonic (MMA), and …

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A Tutorial And Future Research For Building A Blockchain-Based Secure Communication Scheme For Internet Of Intelligent Things, Mohammad Wazid, Ashok Kumar Das, Sachin Shetty, Minho Jo Jan 2020

A Tutorial And Future Research For Building A Blockchain-Based Secure Communication Scheme For Internet Of Intelligent Things, Mohammad Wazid, Ashok Kumar Das, Sachin Shetty, Minho Jo

Computational Modeling & Simulation Engineering Faculty Publications

The Internet of Intelligent Things (IoIT) communication environment can be utilized in various types of applications (for example, intelligent battlefields, smart healthcare systems, the industrial internet, home automation, and many more). Communications that happen in such environments can have different types of security and privacy issues, which can be resolved through the utilization of blockchain. In this paper, we propose a tutorial that aims in desiging a generalized blockchain-based secure authentication key management scheme for the IoIT environment. Moreover, some issues with using blockchain for a communication environment are discussed as future research directions. The details of different types of …

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Recent Developments In The Pyscf Program Package, Qiming Sun, Xing Zhang, Samragni Banerjee, Peng Bao, Marc Barbry, Nick S. Blunt, Nikolay A. Bogdanov, George H. Booth, Jia Chen, Zhi-Hao Cui, Janus J. Eriksen, Yang Gao, Sheng Gun, Jan Hermann, Matthew R. Hermes, Kevin Koh, Peter Koval, Susi Lehtola, Zhendong Li, Junzi Liu, Narbe Mardirossian, James D. Mcclain, Mario Motta, Bastien Mussard, Hung Q. Pham, Artem Pulkin, Wirawan Purwanto, Paul J. Robinson, Enrico Ronca, Elvira R. Sayfutyarova, Maximillian Scheurer, Henry F. Schurkus, James E.T. Smith, Chong Sun, Shi-Ning Sun, Shiv Upadhyay, Lucas K. Wagner, Xiao Wang, Alec White, James Daniel Whitfield, Mark J. Williamson, Sebastian Wouters, Jun Yang, Jason M. Yu, Tianyu Zhu, Timothy C. Berkelbach, Sandeep Sharma, Alexander Yu Sokolov, Garnet Kin-Lic Chan Jan 2020

Recent Developments In The Pyscf Program Package, Qiming Sun, Xing Zhang, Samragni Banerjee, Peng Bao, Marc Barbry, Nick S. Blunt, Nikolay A. Bogdanov, George H. Booth, Jia Chen, Zhi-Hao Cui, Janus J. Eriksen, Yang Gao, Sheng Gun, Jan Hermann, Matthew R. Hermes, Kevin Koh, Peter Koval, Susi Lehtola, Zhendong Li, Junzi Liu, Narbe Mardirossian, James D. Mcclain, Mario Motta, Bastien Mussard, Hung Q. Pham, Artem Pulkin, Wirawan Purwanto, Paul J. Robinson, Enrico Ronca, Elvira R. Sayfutyarova, Maximillian Scheurer, Henry F. Schurkus, James E.T. Smith, Chong Sun, Shi-Ning Sun, Shiv Upadhyay, Lucas K. Wagner, Xiao Wang, Alec White, James Daniel Whitfield, Mark J. Williamson, Sebastian Wouters, Jun Yang, Jason M. Yu, Tianyu Zhu, Timothy C. Berkelbach, Sandeep Sharma, Alexander Yu Sokolov, Garnet Kin-Lic Chan

University Administration Publications

PySCF is a Python-based general-purpose electronic structure platform that supports first-principles simulations of molecules and solids as well as accelerates the development of new methodology and complex computational workflows. This paper explains the design and philosophy behind PySCF that enables it to meet these twin objectives. With several case studies, we show how users can easily implement their own methods using PySCF as a development environment. We then summarize the capabilities of PySCF for molecular and solid-state simulations. Finally, we describe the growing ecosystem of projects that use PySCF across the domains of quantum chemistry, materials science, machine learning, and …

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Ensuring Positive Definiteness In Linear Viscoelastic Material Functions Based On Prony Series, Christopher D. Rehberg Jan 2020

Ensuring Positive Definiteness In Linear Viscoelastic Material Functions Based On Prony Series, Christopher D. Rehberg

Honors Undergraduate Theses

This thesis presents a method to correct for non-positive-definiteness in linear viscoelastic material functions. Viscoelastic material functions for anisotropic materials need to be interconverted in a matrix coefficient prony series form, with a requirement of positive definiteness. Fitting is usually done as a uniaxial prony series, resulting in scalar coefficients. When these uniaxial coefficients are placed in a coefficient matrix, the required positive definiteness cannot be guaranteed. For those matrices that do not meet this requirement, finding the nearest symmetric semi-positive definite form of the matrix results in a viable prony series matrix coefficient with the required positive definiteness. These …

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Degradation From Cmas Infiltration In 7ysz Eb-Pvd Thermal Barrier Coatings, Zachary Stein Jan 2020

Degradation From Cmas Infiltration In 7ysz Eb-Pvd Thermal Barrier Coatings, Zachary Stein

Honors Undergraduate Theses

The lifetime of the high temperature ceramic coating 7 wt.% yttria-stabilized zirconia (7YSZ) is reduced when calcium-magnesium-alumino-silicate (CMAS) particulates enters aero-engines during operation in a sandy or dusty environment, melts, and infiltrates into the coating. 7YSZ undergo both chemical and mechanical degradation from CMAS infiltration during cycling. Characterization methods with synchrotron X-ray diffraction (XRD) provides a non-destructive means to measure the impact of time and temperature on coating degradation with high spatial resolution of 7YSZ coatings infiltrated and annealed by CMAS for 1 hour and 10 hours as well as at 1225 °C and 1250 °C. Additionally, qualitative results of …

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Development Of A Computationally Inexpensive Method Of Simulating Primary Droplet Breakup, Brendon A. Cavainolo Jan 2020

Development Of A Computationally Inexpensive Method Of Simulating Primary Droplet Breakup, Brendon A. Cavainolo

Honors Undergraduate Theses

Liquid droplet impingement on aircraft can be problematic as it leads to ice accretion. There have been many incidents of aircraft disasters involving ice accretion, such as American Eagle Flight 4184. Understanding liquid droplet impingement is critical in designing aircraft that can mitigate the damages caused by icing. However, the FAA's regulations are only specified for "Appendix C" droplets; thus, aircraft designs may not be safe when accounting for droplets such as Supercooled Large Droplets. The assumptions of many models, such as the Taylor-Analogy Breakup (TAB) model, are no longer accurate for Supercooled Large Droplets, and the physics of those …

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Virtual Experiments For Engineering Education, Amy P. Lebanoff Jan 2020

Virtual Experiments For Engineering Education, Amy P. Lebanoff

Honors Undergraduate Theses

In-person engineering instruction relies on the availability of equipment and space. Cost, safety, and scheduling may pose barriers to conducting in-person labs. Virtual experiments may be used to enhance the student experience by, for example, incorporating pre-labs for in-person experiments and providing access to equipment that cannot be safely used in-person. Virtual learning is used in many fields, but there remain questions as to how it should be employed in engineering, an area largely reliant on in-person lab and classroom setups. Earlier studies reviewed the advantages of virtual labs such as demonstrating hard-to-observe phenomena and allowing unlimited trials. This project …

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Maximizing Bass Reflex System Performance Through Optimization Of Port Geometry, Bryce Doll Jan 2020

Maximizing Bass Reflex System Performance Through Optimization Of Port Geometry, Bryce Doll

Honors Undergraduate Theses

A bass-reflex system is a type of loudspeaker design that uses a port or a vent to improve low-frequency performance. The port acts as a Helmholtz resonator which extends the bass response of the system. However, at high drive levels, the air inside the port can become turbulent and cause distortion, noise, and compression. From previous works, it is known that the geometry of the port plays a crucial role in reducing these unwanted effects. This paper serves to provide more insight into optimal port shape by performing several objective tests on a group of 5 different prototype port shapes …

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Passive Scene Reconstruction In Non-Line-Of-Sight Scenarios, Andre Beckus Jan 2020

Passive Scene Reconstruction In Non-Line-Of-Sight Scenarios, Andre Beckus

Electronic Theses and Dissertations, 2020-2023

Locating and identifying hidden objects can prove critical in applications ranging from military reconnaissance to emergency rescue. Although non-line-of-sight (NLOS) reconstruction and imaging have received much attention recently, state-of-the-art methods often use coherent sources (lasers) or require control of the scene. This dissertation focuses on passive NLOS scene reconstruction using the light reflected off a diffusive wall. No control over the light illuminating the scene is assumed, and the method is compatible with the partially coherent fields ubiquitous in both indoor and outdoor environments. In order to counteract the detrimental effects of the wall, rather than measuring the 2-dimensional intensity …

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Evaluation Of Convective Heat Transfer Numerical Methods On Rough Surfaces From Additive Manufacturing, Jose Urcia Jan 2020

Evaluation Of Convective Heat Transfer Numerical Methods On Rough Surfaces From Additive Manufacturing, Jose Urcia

Electronic Theses and Dissertations, 2020-2023

The high versatility of additive manufacturing has led to an increase in use in a number of different fields. Surface roughness then comes as a natural consequence of additive manufacturing which interferes with a smooth wall assumption such as those found in gas turbine blades. The Discrete Element Roughness Method (DERM) has been used to improve convective heat transfer predictions on surface roughness. This work aims to validate the core momentum and heat transfer correlation of DERM through an evaluation of Computational fluid dynamics (CFD)-based solution of the flow around individual roughness elements with the goal of improving the correlations. …

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Modeling Site Specific Urban Propagation Using A Variable Terrain Radiowave Parabolic Equation - Vertical Plane Launch (Vtrpe-Vpl) Hybrid Technique, Pierre Cadette Jan 2020

Modeling Site Specific Urban Propagation Using A Variable Terrain Radiowave Parabolic Equation - Vertical Plane Launch (Vtrpe-Vpl) Hybrid Technique, Pierre Cadette

Electronic Theses and Dissertations, 2020-2023

The development of efficient algorithms for calculating propagation loss in site specific urban environments has been an active area of research for many years. This dissertation demonstrates that, for particular scenarios, a hybrid approach that combines the Variable Terrain Radiowave Parabolic Equation (VTRPE) and Vertical Plane Launch (VPL) models can be used to produce accurate results for a downrange region of interest. The hybrid approach consists of leveraging the 2-D parabolic equation method in the initial propagation region, where backscatter and out of plane energy can be neglected, then transitioning to the more computationally intensive 3-D ray launching method for …

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Scalable Communication Frameworks For Multi-Agency Data Sharing, Shafaq Chaudhry Jan 2020

Scalable Communication Frameworks For Multi-Agency Data Sharing, Shafaq Chaudhry

Electronic Theses and Dissertations, 2020-2023

With the rise in frequency and magnitude of natural disasters, there is a need to break down monolithic organizational barriers and engage with community volunteers. This calls for ease of systems interoperability to facilitate communication, data-sharing and scalability of real-time response, essential for crisis communications. We propose two scalable frameworks that enable multi-agency interoperability and real-time data-sharing. The first framework harnesses the power of social media, artificial intelligence, and community volunteers to form an extended rescue-and-response network that alleviates call center burden and augments the finite capacity of dispatch units. Through an "online 9-1-1" service, affected people can request help …

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Detecting Small Moving Targets In Infrared Imagery, Adam Cuellar Jan 2020

Detecting Small Moving Targets In Infrared Imagery, Adam Cuellar

Electronic Theses and Dissertations, 2020-2023

Deep convolutional neural networks have achieved remarkable results for detecting large and medium sized objects in images. However, the ability to detect smallobjects has yet to achieve the same level performance. Our focus is on applications that require the accurate detection and localization of small moving objects that are distantfrom the sensor. We first examine the ability of several state-of-the-art object detection networks (YOLOv3 and Mask R-CNN) to find small moving targets in infraredimagery using a publicly released dataset by the US Army Night Vision and Electronic Sensors Directorate. We then introduce a novel Moving Target Indicator Network (MTINet) and …

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Econometric Frameworks For Multivariate Models: Application To Crash Frequency Analysis, Tanmoy Bhowmik Jan 2020

Econometric Frameworks For Multivariate Models: Application To Crash Frequency Analysis, Tanmoy Bhowmik

Electronic Theses and Dissertations, 2020-2023

Econometric crash frequency models are a major analytical tool employed for examining the critical factors influencing crash occurrence. However, there are several methodological challenges associated with existing models suggesting a continual need to develop advanced econometric framework to address these gaps. The current dissertation contributes towards addressing the methodological challenges in crash frequency analysis for analyzing multiple crash frequency variables for the same study unit by proposing advanced econometric approaches. The first part of the dissertation contributes to safety literature by conducting a comparison exercise between the two major streams of multivariate approaches - (1) simulation-based approach and (2) analytical …

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