Mechanical Engineering Commons^™

Patient-Specific Analysis Of Aortic Hemodynamics And Wall Shear Stresses In Patients Undergoing Pediatric Bariatric Surgery Using 2d Phase-Contrast Mri, Oluwaferanmi S. Akande, Joao Soares, Nathan Hargan, Dr. Uyen Truong, Haeung Kang, David Lanning

Undergraduate Research Posters

Patient-Specific Analysis of Aortic Hemodynamics and Wall Shear Stresses in Patients Undergoing Pediatric Bariatric Surgery using 2D Phase-Contrast MRI

Feranmi Akande¹ Nathan Hargan² Haesung Kang³ David Lanning³ Uyen Truong⁴ João S. Soares¹

¹ Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University

² Department of Mechanical & Nuclear Engineering, College of Engineering, Virginia Commonwealth University

³ Department of Cardiology, Children’s Hospital of Richmond, Virginia Commonwealth University

Introduction: Severe obesity among today’s youth is a rising epidemic within the United States. Emerging research has linked childhood obesity with shortened life expectancy and early …

อิทธิพลของระยะวิ่งต่อการชาร์จและอัตราการชาร์จของยานยนต์ไฟฟ้าต่อการให้บริการ Ride Sharing ในพื้นที่จุฬา-สามย่าน, ภูมิรพี ขัดศรี

Chulalongkorn University Theses and Dissertations (Chula ETD)

หนึ่งในรูปแบบการเดินทางสมัยใหม่คือ ride sharing ซึ่งเป็นองค์ประกอบสำคัญร่วมกับระบบขนส่งสาธารณะที่จะนำไปสู่รูปแบบ Mobility as a Service ที่จะยกระดับคุณภาพและความสะดวกสบายในการเดินทางในเมืองได้มาก งานวิจัยนี้ศึกษาการใช้งานบริการ ride sharing ในพื้นที่จุฬา-สามย่าน ที่จะตอบสนองพฤติกรรมการเดินทางในพื้นที่มหาวิทยาลัย โดยมีการนำข้อมูลจากบริการจริงมาใช้ในการศึกษาผลกระทบของระยะวิ่งต่อการชาร์จและอัตราการชาร์จของยานยนต์ไฟฟ้าในการให้บริการ ride sharing ผ่านการจำลอง การจำลองบริการใน ride sharing ในพื้นที่จุฬามีขนาด 6.88 ตารางกิโลเมตร ในส่วนของ range มี 3 ขนาดได้แก่ long range, medium range, short range ตามลำดับ อัตราการชาร์จแบ่งออกเป็น 3 ขนาดได้แก่ fast charge, medium charge, slow charge ดังนั้น การจำลองจึงมี 9 สถานการณ์จำลองด้วยกันและใช้ยานพาหนะ 20 คัน ตัวชี้วัดสำหรับการจำลองการให้บริการ ได้แก่ Vehicle Kilometer Traveled (VKT) , service distance, %served และรายได้จากการให้บริการ ผลลัพธ์จากการวิเคราะห์พฤติกรรมและรูปแบบการเดินทางในพื้นที่ด้วย ride sharing ภายในจุฬาลงกรณ์มหาวิทยาลัยพบว่ามีช่วงการใช้งานสูงสุดอยู่ในช่วง 11:30-12:30 น. โดยมีจำนวนการเรียก 1 คนราว 70% และราว 92% คือการเรียกรถแบบไม่เกิน 3 คน ระยะเดินทางด้วย ride sharing ขั้นต่ำอยู่ที่ระยะทาง 400 เมตร สำหรับผลลัพธ์จากการจำลองทั้ง 9 สถานการณ์จำลองนั้น พบว่าผลกระทบจากการปรับอัตราการชาร์จนั้นส่งผลต่อการให้บริการมากกว่า range อย่างเห็นได้ชัดในทุกกรณี ซึ่งจากการสอบทวนผลลัพธ์กับผู้ประกอบการ ผลลัพธ์สอดคล้องกับการให้บริการจริง นอกจากนั้นจากผลลัพธ์พบว่าการเพิ่ม Range นั้นไม่ได้ให้ผลลัพธ์การบริการที่ดีขึ้นเสมอไป โดยกรณี short range:medium charge มี %served …

Low-Fidelity Design Optimization And Parameter Sensitivity Analysis Of Tilt-Rotor Evtol Electric Propulsion Systems, Tyler Critchfield, Andrew Ning

Faculty Publications

Urban air mobility requires a multidisciplinary approach to tackle the important chal- lenges facing the design of these aircraft. This work uses low-to-mid fidelity tools to model rotor aerodynamics, blade structures, vehicle aerodynamics, and electric propulsion for a tilt-rotor electric vertical takeoff and landing (eVTOL) aircraft. We use gradient-based design optimization and extensive parameter sensitivity analysis to explore the design space and complex tradeoffs of tilt-rotor distributed electric propulsion systems.

Triangular Fin Array Passively Actuated By Bimetallic Coils For Cubesat Thermal Control, Josh Cannon, Rydge B. Mulford, Brian D. Iverson

Faculty Publications

CubeSat thermal control can be especially demanding due to volume and size constraints, high power dissipation per unit surface area, and highly variable internal and external heat loads. As such, CubeSat developers must rely on thermal control systems that meet the specific requirements of their mission and environmental conditions. Deployable radiators enable satellites to increase their radiative surface area and to reveal highly emissive surfaces during times when increased heat rejection is desired. In colder conditions, when decreased heat loss is preferable, the radiators can be stowed. Passive thermal control systems are unpowered and can increase system reliability by not …

Use Of Bioheat Modeling To Characterize And Optimize Implantable Medical Devices And Neuromodulation Technologies, Adantchede Louis Zannou

Dissertations and Theses

Medical device development includes prototyping, benchtop characterization, preclinical studies, and clinical trials. Understanding the limitations and potential adverse effects of medical devices prior to their administration in humans is a crucial first step. Optimizing medical devices is essential to employing technology and improving patients care. Computational modeling is widely adopted as a powerful tool to predict stimulation/recording parameter optimization, rapid electrode/device prototyping, investigating novel mechanism of action, and testing working principles of any medical devices. Many implantable neuromodulation technologies including Spinal Cord Stimulation (SCS), which provide substantial therapeutic benefit for patient population with lower back pain, produces heat via the …

An Experimental Study Of The Impinging And Freezing Dynamics Of A Colloidal Droplet On Solid Surfaces, Andro Fayek Abdelmalek

Dissertations and Theses

In modern manufacturing, the production of complex components with intricate geometries and varying material compositions has become essential. To meet these demands, additive manufacturing (AM) has gained prominence. Various 3D printing technologies, such as stereolithography (SLA), selective laser sintering (SLS), and plastic extrusion, have been developed to produce finished components. However, each technology has its limitations, including restricted printing resolution or limited material selection. A novel idea in additive manufacturing involves the utilization of inkjet printing nozzles with colloidal fluid and implementing the freeze-dry method. This innovative technique entails depositing colloidal droplets onto a freezing substrate using an inkjet head. …

Microfluidic Dual-Gel Cell Culture Model For Studying Cell Migration Under Controlled Interstitial Flow, Alimohamamd Anbari

Dissertations and Theses

Abstract

Interstitial flow, the slow flux of fluid occurring in the interstitial space of the extracellular matrix (ECM), affects the migration of many cell types through individual and synergistic contributions of several biophysical and biochemical phenomena. Notably, interstitial flow is linked to ECM permeability and provides direct mechanical cues via shear and normal stress. Additionally, the flow also couples with biomolecular diffusion to provide chemotactic signals to the cells. Recent in vitro studies have indicated that tumor cell migration is affected by interstitial fluid velocity and ECM permeability through the mechanisms of (1) autologous chemotaxis and (2) integrin-mediated focal adhesion …

Enhancing Traffic Safety In Unpredicted Environments With Integration Of Adas Features With Sensor Fusion In Intelligent Electric Vehicle Platform With Implementation Of Environmental Mapping Technology, David S. Obando Ortegon

College of Graduate Studies: Theses & Dissertations

A major objective on society is to reduce the number of accidents and fatalities on the road for drivers, and pedestrians. Therefore, the automotive engineering field is working on this problem through the development and integration of safety technologies such as advanced driving assistance systems. For this reason, this work was intended to develop and evaluate the performance of different ADAS features and IV technologies under unexpected scenarios. This by the development of safety algorithms applied to the intelligent electric vehicle designed and built in this work, through the use of ADAS sensors based on sensor fusion. Evaluation of AEB, …

Investigations Of A Surrogate Fuel Based On Fischer-Tropsch Gtl And Ctl In Cvcc, Idi And Di Compression Ignition Engines, Amanda C. Weaver

College of Graduate Studies: Theses & Dissertations

With the increase in availability, feedstocks, and properties of alternative fuels, compatibility issues emerge between current engine platforms often requiring a limit on the blend percentage of alternative fuel in conventional fuel or alteration to the engine platform. Two key metrics were identified, autoignition quality and lubrication characteristics, as vital for the proper function of a compression ignition engine, and if the blend of alternative fuels matches these two criteria for the diesel standard, then the resulting blend percentage can be considered as a viable alternative for complete replacement of conventional petroleum ULSD. Autoignition quality was matched using blends S-8, …

Piv Measurements Of Open-Channel Turbulent Flow Under Unconstrained Conditions, James K. Arthur

Faculty Journal Articles

Many open-channel turbulent flow studies have been focused on highly constrained conditions. Thus, it is rather conventional to note such flows as being fully developed, fully turbulent, and unaffected by sidewalls and free surface disturbances. However, many real-life flow phenomena in natural water bodies and artificially installed drain channels are not as ideal. This work is aimed at studying some of these unconstrained conditions. This is achieved by using particle image velocimetry measurements of a developing turbulent open-channel flow over a smooth wall. The tested flow effects are low values of the Reynolds number based on the momentum thickness Re …

Using Long Short-Term Memory (Lstm) Networks With The Toy Model Concept For Compressible Pulsatile Flow Metering, Indranil Brahma

Faculty Journal Articles

The metering of periodically oscillating pulsating flow has traditionally relied on eliminating pulsations, which is not possible for many systems such as internal combustion engines. Recent advances in the Deep Learning Suite of tools allow the extraction of useful information from complex signals acquired by inexpensive sensors. In this work, Long Short-Term Memory (LSTM) networks have been proposed to meter highly compressible pulsatile flow by learning the relationship between the average flow rate and the temporal patterns of standard orifice measurements. The model was built and evaluated with separate training and testing datasets that had different pulsation frequencies and waveforms. …

Acausal Modeling Of Wind Turbines With Validation And Control Studies, Kazi Ishtiak Mohsin

Graduate Thesis and Dissertation 2023-2024

This thesis involves the modeling, validation, and control studies of a Control-Oriented, Reconfigurable, and Acausal Floating Turbine Simulator (CRAFTS), that is currently under development. CRAFTS uses Modelica®, an object-oriented, declarative, multi-domain modeling language for physical system modeling in the Dymola environment. The CRAFTS simulator facilitates rapid dynamic simulation of wind turbines with various model variants and enables control co-design.

A major emphasis of this thesis is in the validation of the CRAFTS simulator for a 15-MW land-based wind turbine through several test cases. These test cases were collaboratively developed in conjunction with other participating research entities. CRAFTS has undergone rigorous …

Comparison Of Dynamics Stability Testing Techniques With Magnetic Suspension Wind Tunnel Capabilities, Otoniel A. Ramirez, Mark Schoenenberger, David E. Cox, Colin P. Britcher

Mechanical & Aerospace Engineering Faculty Publications

Dynamic stability testing techniques currently utilized at NASA Langley Research Center (LaRC) are conducted in multiple facilities and consists of free flight, forced oscillation, and free-to-oscillate tests. The NASA/ODU Magnetic Suspension and Balance System (MSBS) has been recommissioned to explore its utility as an additional facility to expand the dynamic stability test capabilities currently available at NASA LaRC. Simulations were created to replicate each current test facility and method as closely as possible. Data collected from the simulated environments was corrupted with replicated noise sources of the different testing environments and then compared to real data collected during tests when …

Evaluating The Impact Of Increased Cycling On Thermal Power Plants Due To Wind Energy Penetration In The Midwest: A Case Study, Joscelyne Larson

Electronic Theses and Dissertations

One of the most significant shifts in the mix of U.S. electricity generation over the past few years has been the rapid expansion of renewable energy resources, especially solar and wind. However, fossil fuels are still necessary to fulfill the world’s energy requirements. Despite efforts to increase the use of renewable energy sources, these sources can be at times unreliable, causing countries around the world to continue to rely on base load units such as coal and natural gas. This decrease in fossil fuels and increase in renewable energy sources presents many complex issues in terms of power system planning, …

Passive Earplug Including Helmholtz Resonators Arranged In Series To Achieve Broadband Near Zero Occlusion Effect At Low Frequencies, Kevin Carillo, Franck Sgard, Olivier Dazel, Olivier Doutres

Études primaires

The use of passive earplugs is often associated with the occlusion effect: a phenomenon described as the increased auditory perception of one's own physiological noise at low frequencies. As a notable acoustic discomfort, the occlusion effect penalizes the use and the efficiency of earplugs. This phenomenon is objectively characterized by the increase in sound pressure level in the occluded ear canal compared to the open ear canal. Taking inspiration from acoustic metamaterials, a new design of a three-dimensional printed “meta-earplug,” made of four Helmholtz resonators arranged in series, is proposed for achieving near zero objective occlusion effect measured on artificial …

Analytical Heat Transfer Modeling Of The Microwave Heating Process: A Focus On Carbon Black, Craig Offutt

Graduate Theses, Dissertations, and Problem Reports (ETD)

Electronic waste (e-waste) has become a significant environmental issue due to the rapid advancement of technology, increasing demand for electronic devices, and shorter lifespan of electronics. One critical step in processing the e-waste involves ball milling as a means of preparing the recycling e-waste for the recovery of critical materials. Ball milling is a technique that involves the mechanical crushing and grinding of electronic waste to reduce its size and improve its reactivity during recovery. Our focused recovery technique is based on a microwave recovery technique of these critical materials from e-waste. The size and distribution of the e-waste with …

Methane Emissions Produced By Pneumatic Devices And Produced Water Tanks On Natural Gas Wellsites, Benjamin William Thornton

Graduate Theses, Dissertations, and Problem Reports (ETD)

Abstract

Methane Emissions Produced by Pneumatic Devices and Produced Water Tanks on Natural Gas Wellsites

Benjamin W. Thornton

In recent years, more scrutiny has been placed on the release of greenhouse gasses (GHGs) by the oil and gas industry in North America as climate concerns increase. In the coming years, stricter regulations proposed by the Environmental Protection Agency (EPA) concerning the release of GHGs will further direct attention to GHG emissions quantification, modeling, and overall reduction. Active natural gas wellsites employ production equipment that routinely emits methane during normal operation. Production equipment often includes, but is not limited to, gas …

Internal Surface Nanostructure And Chemistry Modification On Porous Cathode Of Solid Oxide Fuel Cell To Mitigate Cr Contamination From Interconnect, Liang Liang

Graduate Theses, Dissertations, and Problem Reports (ETD)

Solid Oxide Fuel cells (SOFCs) could convert the chemical energy from a variety of fuels into electricity. It has become a competitive power source due to its advantages, such as high efficiency and flexibility in fuel options. It can be operated under a wide range of operating temperatures, which makes them easy to be applied and developed into applications. To further increase the lifetime and reduce the cost of SOFC systems to make them more competitive and affordable for commercialization, the catalytic activity for oxygen reduction reaction at the cathode needs to be improved. One significant technical opportunity is to …

Combustion Characteristics Of Methane, Ethane, Propane, And Butane Blends Under Conditions Relevant Of A Dual-Fuel Diesel And Natural Gas Engine, Christopher Joseph Ulishney

Graduate Theses, Dissertations, and Problem Reports (ETD)

As natural gas production infrastructure is already in place in most of the world and will continue expanding for the foreseeable future, natural gas is an alternative to traditional liquid petroleum fuels in heavy-duty engines. Dedicated natural gas or dual-fuel diesel-natural gas heavy-duty engines are alternatives to diesel-only power generation equipment. One challenge is the large variation in the natural gas composition available for such applications, which is known to significantly affect engine’s combustion characteristics and the emissions composition. As the literature on dual-fuel combustion under low load engine operating conditions that use more realistic natural gas mixtures (i.e., mixtures …

Accelerating Manufacturing Decisions Using Bayesian Optimization: An Optimization And Prediction Perspective, Taofeeq Olajire

Graduate Theses, Dissertations, and Problem Reports (ETD)

Manufacturing is a promising technique for producing complex and custom-made parts with a high degree of precision. It can also provide us with desired materials and products with specified properties. To achieve that, it is crucial to find out the optimum point of process parameters that have a significant impact on the properties and quality of the final product. Unfortunately, optimizing these parameters can be challenging due to the complex and nonlinear nature of the underlying process, which becomes more complicated when there are conflicting objectives, sometimes with multiple goals. Furthermore, experiments are usually costly, time-consuming, and require expensive materials, …

Design And Validation Of An Aerodynamic System For A Formula Sae® Vehicle Using Vehicle Dynamic Simulation And Experimentation, Evan S. Cole

Graduate Theses, Dissertations, and Problem Reports (ETD)

This thesis presents the design, simulation, and experimental validation for the aerodynamic system for a Formula SAE® vehicle. The Society of Automotive Engineers ® (SAE) hosts a collegiate competition annually called Formula SAE® where students design, fabricate, and test a small “formula style” vehicle. The vehicle performs in relatively slow maneuvers, around different courses and tests to evaluate the vehicle’s overall performance. Over the years, collegiate teams have put significant research into the design and manufacturing of the aerodynamics of these vehicles. In order to justify this undertaking for future teams at West Virginia University’s Formula SAE® program, a comprehensive …

Imitation Learning For Swarm Control Using Variational Inference, Hafeez Olafisayo Jimoh

Graduate Theses, Dissertations, and Problem Reports (ETD)

Swarms are groups of robots that can coordinate, cooperate, and communicate to achieve tasks that may be impossible for a single robot. These systems exhibit complex dynamical behavior, similar to those observed in physics, neuroscience, finance, biology, social and communication networks, etc. For instance, in Biology, schools of fish, swarm of bacteria, colony of termites exhibit flocking behavior to achieve simple and complex tasks. Modeling the dynamics of flocking in animals is challenging as we usually do not have full knowledge of the dynamics of the system and how individual agent interact. The environment of swarms is also very noisy …

Stability Of Ruddlesden-Popper Phase Lanthanum Nickelate As Air Electrode For Reversible Solid Oxide Cells, Daniel De Lorenzo Moreira

Graduate Theses, Dissertations, and Problem Reports (ETD)

This thesis studied the long-term stability of Ruddlesden-Popper phase Lanthanum Nickelate under operating conditions as the air electrode for Reversible Solid Oxide Cells (R-SOC). Renewable energies have gone through increase in popularity throughout the last decades, mainly due to the consequences of the rapid population growth in the world. These new energies have been pointed as the rightful successor of fossil fuel energies in order to decrease the environmental impact of our day-to-day life. Solid Oxide Fuel Cells as well as Solid Oxide Electrolysis Cells are believed to be the key to stabilizing the energy supply when environmental conditions are …

Simulating Energy Performance Of Buildings: A Study Using Equest And Energy Star® Portfolio Manager, Sabin Wagle

Graduate Theses, Dissertations, and Problem Reports (ETD)

The urgent need for improving building energy efficiency in response to global warming and environmental sustainability has highlighted the importance of practical techniques to optimize energy performance. The study utilizes the eQUEST simulation engine and Energy Star® Portfolio Manager to evaluate retrofit and design parameters and conduct a sensitivity analysis to explore the impact of different parameters on building energy performance. The study develops building energy models in eQUEST using data from two fully operational Distribution centers. It is calibrated using the Normalized Mean Bias Error (NMBE) and Coefficient of Variation of Root Mean Square Error (CV(RMSE)) method, meeting the …

Development Of A Quasi-Dimension Gci Combustion Model Aided By Cfd, Jinsu Kim

Graduate Theses, Dissertations, and Problem Reports (ETD)

Advanced combustion strategies have been proposed to improve fuel efficiency while minimizing exhaust emissions. Gasoline compression ignition (GCI) combustion featuring partially premixed compression ignition (PPCI) and diffusion combustion has been recognized as an attractive, viable combustion strategy for its potential and advantages over conventional diesel and gasoline engines. The optimization of the GCI engine system requires the development of a quasi-dimensional GCI combustion model capable of simulating GCI combustion while requesting less computational burden than CFD simulation, which is very critical in engine system simulation. This study developed a quasi-dimension, phenomenological combustion model for PPCI and diffusion combustion to facilitate …

Localization Of People In Gnss-Denied Environments Using Neural-Inertial Prediction And Kalman Filter Correction, Lauren N. Cash

Graduate Theses, Dissertations, and Problem Reports (ETD)

This thesis presents a method based on neural networks and Kalman filters for estimating the position of a person carrying a mobile device (i.e., cell phone or tablet) that can communicate with static UWB sensors or is carried in an environment with known landmark positions. This device is used to collect and share inertial measurement unit (IMU) information — which includes data from sensors such as accelerometers, gyroscopes, and magnetometers — and UWB and landmark information. The collected data, in combination with other necessary initial condition information, is input into a pre-trained deep neural network (DNN) which predicts the movement …

Pressure Induced By Roll-Down Foam-Earplugs On Earcanal, Ahmed Dalaq, Luiz Melo, Franck Sgard, Olivier Doutres, Éric Wagnac

Études primaires

Physical discomfort of earplug is a common complaint, so much so it jeopardizes the health and safety of workers, resulting in frequent noncompliance to proper wearing of earplugs. A pressing need thus arises to understand the underlying mechanics for the interaction of earplugs with earcanal walls. An idealized cylindrical geometry of earcanal is first treated with computational and analytical modeling to predict the pressure induced by roll-down cylindrical PVC foam earplugs. In order to predict representative pressure values and distribution, we estimated the hyperelastic properties of foam-based earplugs and characterized their behavior using a stent testing machine (J-Crimp^TM machine) …

High Signal-To-Noise Ratio Event-Driven Mems Motion Sensing, Mohammad Mousavi, Mohammad Alzgool, Benyamin Davaji, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

Two solutions for improving MEMS triboelectric vibration sensors performance in contact-separation mode are reported experimen- tally and analytically. Triboelectric sensors have mostly been studied in the mesoscale. The gap variation between the electrodes induces a potential difference that represents the external vibration. Miniaturizing the device limits the sensor output because of the limited gap. This work offers a warped MEMS diaphragm constrained on its edges. The dome-shaped structure provides one order of magnitude larger displacement after contact-separation than standard designs resulting in one order of magnitude greater volt- age and signal-to-noise-ratio. Secondly, micro triboelectric sensors do not operate unless the …

Solid-State Electrolytes For Long Duration Molten Sodium Batteries, Ryan C. Hill

Theses and Dissertations--Chemical and Materials Engineering

Rechargeable batteries have become a staple of modern society, driving the development and expansion of portable electronics and electric vehicles. The long lifetime and high energy density provided by batteries have made them excellent candidates for use in the emerging field of long duration, grid-scale energy storage. However, traditional battery chemistries, such as Li-ion, are not an ideal solution for grid-scale storage, due to high-cost raw materials that are often sourced from volatile markets. Sodium-based batteries are a promising alternative for long duration storage, owing to the domestic abundance of raw materials and energy densities that nearly rival that of …

Finite Element Analysis Of 3d-Printed Pcl Scaffolds, Ireolu K. Orenuga, Joao Soares, Phillip D. Glass, Daeha Joung Ph.D.

Undergraduate Research Posters

Finite Element Analysis of 3D-printed PCL Scaffolds for Synergizing Cellular Micro-Environment and Mechanical Stimuli to Enhance Engineered Tissue Growth in Vitro

Ireolu Orenuga,1 Phillip Glass,2 Daeha Joung,2 Joao S. Soares1

1. Department of Mechanical and Nuclear Engineering, College of Engineering, Virginia Commonwealth University
2. Department of Physics, College of Humanities & Sciences, Virginia Commonwealth University

Introduction: Tissue engineering aims to create viable and functional engineered tissues via biodegradable scaffolds and autologous cells. Scaffolds play an essential part in organizing the architecture of developing tissues and aid in the proper function of implants acutely by serving as mechanical support and long-term by …