Master of Science (MS), Ohio University, 2024, Civil Engineering (Engineering and Technology)

In the field of transportation engineering, there has been a shift towards implementing Connected Vehicle (CV) Technology as a means of improving transportation systems. This approach is becoming increasingly important due to limited space, high delay on roadways, and significant crashes. The CV technology is expected to be the most effective solution for making transportation systems more functional and safer, as it enhances drivers' decision-making abilities and helps to control traffic flow. To assess the impacts of CV technology, simulations and closed-course testing have been conducted. In addition, some pilot studies have been carried out in urban settings, where the goal is to achieve "zero deaths." However, a comprehensive understanding of the applications of Connected Vehicles in rural settings is necessary, as driver behavior can be unpredictable and location-dependent. This research aims to evaluate the performance of four CV applications in a rural environment: Red Light Violation Warning (RLVW), Pedestrian in Signalized Crosswalk (PEDINXWALK/ PEDPSM), Curve Speed Compliance (CSPDCOMP), and Speed Compliance in work zones (SPDCOMPWZ). There were no work zones in the study area hence analysis on SPDCOMPWZ was not included in this study. Though the research had four CV applications but each driver had only three applications installed in their vehicle. Hence the study obtained 4 different groups for all 3-paired CV applications. The study analyzed the impact of these applications on drivers' behavior and their reactions to evaluate the performance of CV applications. The analysis focused on drivers' speeds since speed happens to be one of the primary traffic parameters that can provide in-depth information on driver's behavior on the road. The driver's speed is analyzed once they receive a warning or trigger prior to a potential violation of these specific traffic rules; 1.Running red-light, 2. Conflict/ potential crash between vehicle and pedestri (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2020, Mechanical Engineering

The goal of this work is to investigate a new approach for modeling the combustion process of a premixed internal combustion engine. The outcome is the development and validation of a simple, computationally-inexpensive model of the premixed engine combustion process which is capable of predicting the mean mass fraction burned (MFB) profiles of combustion without the extensive use of model calibration that is typically required of this class of modeling. One of the main contributions of this research is the development of a new flame brush thickness dynamics (FBTD) theory which allows the prediction of the transient turbulent flame speed when the statistical description of turbulence is known. The predicted transient turbulent flame speed is then passed in a re-derived form of the Wiebe function, referred to as the BRN model, to determine the instantaneous MFB of the mixture within the engine's combustion chamber. This new low fidelity combustion model (BRN + FBTD) has been validated against three sets of data in this work. The first set is a theoretical comparison between the FBTD theory and instantaneous G-equation solutions across a range of turbulence parameters for a synthetic, frozen, turbulent flow field. The second being a comparison of a 0D engine simulator utilizing the BRN + FBTD combustion model against real engine cylinder pressure derived measurements of the mass fraction burned profile for a 3.5L GDI V6 engine. Lastly, the dynamics of the flame radius and flame brush thickness as predicted by BRN + FBTD are compared against high speed optical engine measurements on a laser sheet illuminated plane of an optically accessible 3.5L GDI V6 engine from the same family as the two previous datasets. In each case, the good agreement seen between simulation and experiment presented here suggests that the BRN + FBTD combustion model is capable of predicting the MFB profile without the hardware or condition specific calibrations typically required of this cla (open full item for complete abstract)

MS, University of Cincinnati, 2020, Engineering and Applied Science: Electrical Engineering

In this thesis we apply the newly developing field of deep learning to the task of speed sign detection and recognition. Previous work has mostly used traditional image processing techniques or shallow neural networks and has focused on simple images that contain only the speed sign or are taken from ideal distances. We have chosen to apply our novel speed sign detection and recognition method to the complex images that contain a large variety of other objects, variable illumination or brightness levels, potential partial obstructions of the signs, and variable distance of the sign from the camera. While related work classified speed signs as one class, our work classifies speed signs into different classes based on their numerical speed value. The existing state-of-the-art YOLO (You Only Look Once) framework is applied to complete the task of object detection. YOLO is a more desirable choice for an object detection method for speed signs than other methods due to the advantages of YOLO. YOLO's main advantages are being extremely fast, making less background errors than other methods, and being highly generalizable by having the capability to handle both natural images and artwork. This new method of speed sign detection is fast enough to detect and recognize speed signs in real-time. Future autonomous vehicles will benefit from this method because it allows for the numerical speed value of a speed sign to be determined in real-time from the complex images that occur on the road.

Master of Sciences (Engineering), Case Western Reserve University, 2024, EECS - System and Control Engineering

Wire Arc Additive Manufacturing (WAAM) has emerged as a promising technology for producing metal parts, offering reduced lead times and costs compared to traditional methods. However, achieving optimal process parameters in WAAM and accurately predicting bead height remain challenging due to complex interactions between input variables and output characteristics. This thesis addresses the challenge of developing a machine learning regression model to predict the average bead height of single deposited beads, crucial for building simple and complex shapes in WAAM. The research investigates the relationship between four critical input parameters - Voltage, Wire Feed Speed (WFS), Travel Speed, Contact Tip to Work Distance (CTWD) - and their influence on bead dimensions in WAAM. A comprehensive experimental setup is employed, utilizing a custom-built WAAM 3D metal printer equipped with a gantry system and controlled by a Duet 3 controller. Steel wire ER70s-6 with a diameter of 0.9mm is used for printing, producing single beads with heights ranging from 2.5mm to 3.55mm. A total of 248 experiments are performed using the Arc-One Machine at Case Western Reserve University (CWRU) for the model training, which are then analyzed. A machine learning regression model is built using this dataset, with four inputs (Voltage, Travel Speed, Wire Feed Speed, Contact Tip to Work Distance) and two corresponding outputs (average bead height and variance of bead heights). Various analytical techniques were explored to predict the average bead height and its variance, leading to the adoption of the Gradient 18 Boosting regression model as the most effective approach. Two models, a forward model and an inverse model, were developed to predict WAAM parameters and outputs. The forward model predicts the average bead height and variance based on the input parameters (Voltage, Wire Feed Speed, Travel Speed, and Contact Tip to Work Distance), providing insights into how th (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2023, Electrical and Computer Engineering

Need for high data rates in various systems as switches in data centers, and Artifcial Intelligence processors has increased signifcantly in the recent years. However, channel loss increases at high frequencies degrading signal integrity and limiting the maximum achievable data rate. Conventional approaches to achieve high data rates using sophisticated signal processing techniques have led to complexity explosion in the wireline transceivers. This complexity explosion degrades the energy efciency signifcantly, and poses a serious challenge to meeting the high data rate demand at a reasonable power cost. This dissertation paves the way to achieving ultra high data rates at a low power cost through complexity reduction. It presents 2 new receiver architectures, which are able to expand and contract, consuming only the power needed at a specifc data rate. Besides developing new receiver architectures, new circuit techniques used in analog signal processing are presented, which consume only 25 % of the power consumed using conventional analog signal processing circuits. The 1st receiver architecture is a programmable incremental contingent decision equalizer consisting of N stages, where each stage cancels one Inter Symbol Interference (ISI) tap and suppresses the others. Instead of delaying the analog signal, and multiplying it by some weight as in a conventional Feed Forward Equalizer (FFE), the analog signal is quantized and the digital output of the quantizer is used to subtract ISI. This receiver architecture was designed in 28 nm CMOS targeting 80 Gb/s achieving 1 pJ/bit power efciency. Measurements prove the validity of the proposed architecture along side the proposed circuit techniques. The 2nd receiver architecture improves the equalization capability of the 1st architecture through providing a correction path to compensate for the wrong ISI subtraction due to tentative quantizer decisions, specifcally at high loss channels. Timing requirements for this re (open full item for complete abstract)

Master of Science (MS), Ohio University, 2020, Mechanical Engineering (Engineering and Technology)

Fatigue failures are sudden and catastrophic, and for critical parts must be prevented through proper design. Fatigue testing of materials yields data critical for proper design but takes large spans of testing time to complete with conventional methods. Therefore, high speed fatigue testing that produces quality data is advantageous for reducing costs and time. However, it has been shown that testing speeds may affect material performance, both in static tensile testing and dynamic fatigue testing. The effect of strain rate on material performance in static tensile testing and how it relates to fatigue testing performance at commensurate strain rates was the primary objective for this thesis work for sheet Ti-6Al-4V and Inconel 718. Implementing a vibration-driven, fully reversed bending fatigue test protocol leveraging high speed testing capability, a comparable forced displacement bending fatigue test protocol, and a high speed tensile test protocol implementing Digital Image Correlation (DIC), stress versus strain data and S-N curve data was acquired to examine two strain-rates of fatigue and tensile testing. Higher ultimate tensile strengths were observed in high strain rate tests as compared to low strain rate tests, 4.23% higher for Ti-6Al-4V and 1.91% for Inconel 718. Ti-6Al-4V exhibited higher fatigue strength in high speed tests than low speed, but Inconel 718 exhibited lower fatigue strength at high speeds as compared to low speeds.

Doctor of Philosophy, The Ohio State University, 2014, Industrial and Systems Engineering

The part drawability in stamping process can be improved by many factors, including blank geometry, lubricant, surface finish, the deformation speed and the blank holder force. Lowering the friction between the tool and the workpiece can reduce fracture potential in the part. Friction is affected by contact pressure, temperature, sliding velocity, die material/coating and surface texturing. In this study, only the effects of lubrication and surface were investigated. Various lubricants such as dry film lubricant and wet lubricants, which were developed for aluminum alloys, were evaluated using cup draw test. Tribological test such as cup draw test was utilized to evaluate the lubricity of the selected lubricants. It was found out that dry film lubricant performed better than wet lubricants in the deep drawing of aluminum alloys. Mill finish and Electrical Discharge Texturing (EDT) that are surface topographies for aluminum alloys, were evaluated by conducting cup draw test in the study. It was concluded that EDT can provide better lubrication condition at the interface between workpiece and die, compared to Mill Finish. Blank geometry can be optimized to improve the part drawability. In this study, different blank geometries were studied by using FE simulations to optimize the blank geometry to be used in the servo press tryouts. It was found out blank with an optimal blank shape, such as four corners chamfered blank shape, could give less wrinkling. Designing a proper tooling also can improve the part drawability by selecting the optimum punch/ die radii and punch and die clearance. In this study, FE simulations were conducted to determine the optimum punch and die radii and clearance between punch and die. By using a mechanical servo press, which can 1) vary the ram speed at any slide position and 2) vary the blank holder force through the stroke can improve the part by selecting the optimal deformation speed and blank holder force. In this study, the eff (open full item for complete abstract)

Master of Science (MS), Wright State University, 2007, Computer Science

Deshpande, Kshitij S. MS, Department of Computer Science and Engineering, Wright State University, 2007. Fuel Flow Control Issue in Jet Engines: An Evolvable Hardware Approach. Dealing with unexpected dynamic loads in Jet and Turbine engines have always been a matter of concern and an active area of research. This thesis is an initial attempt to apply Evolvable Hardware methods for augmenting classical control methods in a generic turbine engine model. In this work, the Air Force Research Laboratory Generic Turbine Engine Model was converted into C and interfaced with a simulation of a EH VLSI control chip currently under development. The simulated EH device was allowed to evolve to augment the simulated engine's standard FADEC controller so that the whole system could tolerate unexpected, large loads to its low-pressure compression shaft. The unassisted FADEC is not capable of this and will catastrophically fail when asked to do so. We will show that the chip can evolve an effective augmentative controller with relatively little computational expenditure and discuss how these techniques might be applied to similar problems in the future.

Master of Science (MS), Wright State University, 2006, Human Factors and Industrial/Organizational Psychology MS

This study examined active regulation of speed during a low-altitude flight task as a function of global optical flow rate, speed, and the presence or absence of a concurrent altitude disturbance. The results showed that altitude clearly had an impact on speed control; specifically, control of speed was much more difficult when altitude disturbances were present. Even in the no altitude disturbance conditions, performance tended to be best at lower altitudes. Consistent with previous research, the results suggest that speed and altitude changes have additive effects on speed judgments. This is inconsistent with the simple global optical flow rate hypothesis that had suggested multiplicative effects; however, it is consistent with the general notion that judgments of self-motion are based on properties of optical flow fields (i.e., angles and angular rates) that depend on distance and motion relative to textured surfaces.

Doctor of Engineering, Cleveland State University, 2011, Fenn College of Engineering

High-Speed Machining (HSM) spindles equipped with Active Magnetic Bearings (AMBs) are envisioned to be capable of autonomous self-identification and performance self-optimization for stable high-speed and high quality machining operation. High-speed machining requires carefully selected parameters for reliable and optimal machining performance. For this reason, the accuracy of the spindle model in terms of physical and dynamic properties is essential to substantiate confidence in its predictive aptitude for subsequent analyses. This dissertation addresses system identification, open-loop model development and updating, and closed-loop model validation. System identification was performed in situ utilizing the existing AMB hardware. A simplified, nominal open-loop rotor model was developed based on available geometrical and material information. The nominal rotor model demonstrated poor correlation when compared with open-loop system identification data. Since considerable model error was realized, the nominal rotor model was corrected by employing optimization methodology to minimize the error of resonance and antiresonance frequencies between the modeled and experimental data. Validity of the updated open-loop model was demonstrated through successful implementation of a MIMO µ-controller. Since the µ-controller is generated based on the spindle model, robust levitation of the real machining spindle is achieved only when the model is of high fidelity. Spindle performance characterization was carried out at the tool location through evaluations of the dynamic stiffness as well as orbits at various rotational speeds. Updated model simulations exhibited high fidelity correspondence to experimental data confirming the predictive aptitude of the updated model. Further, a case study is presented which illustrates the improved performance of the µ-controller when designed with lower uncertainty of the model's accuracy.

Master of Science (M.S.), University of Dayton, 2013, Chemical Engineering

This research focuses on drawdown of floating solids with up-pumping agitators in a batch vessel equipped with baffles for solid–liquid system. Up-pumping agitators incorporate floating solids via a combination of different mechanisms turbulence engulfment, mean drag and vortices formed behind baffle. After screening five different baffle arrangements, standard full length baffle was found to work well with up-pumping agitators. The use of standard baffling for solids drawdown lead to better understanding of power and torque. The optimum design of the up-pumping agitator for drawdown of floating solids requires understanding effects of various design parameters, such as impeller type, diameter, and submergence and their effect on drawdown speed, torque and power. This study considers comparing two types of impeller Pitched Blade Turbine (P-4) and Chemineer HE-3. Totally nine different impeller to tank diameter ratios ranging from twenty to fifty percentage of tank diameter with submergences varying from ten to seventy percent of the liquid height which is equal to tank diameter were tested to find optimum design. The drawdown speed for P-4 and HE-3 increased with increase in submergence and decreased with increase in the impeller diameter. The drawdown speed of P-4 and HE-3 are related to impeller to tank diameter ratio by a power-law relation. The drawdown speed of P-4 and HE-3 are also related to impeller submergence by a power-law relation. The power correlations are given below. P-4 HE-3 Njd (D/T) -1.39 Njd (D/T) -1.60 0.2 < D/T < 0.5 and 0.1 < S/T <0.7 Njd (S/T) 0.32 Njd (S/T) 0.15 0.2 < D/T < 0.5 and 0.1 < S/T <0.4 Njd (S/T) 1.45 Njd (S/T) 0.47 0.2 < D/T < 0.5 and 0.4 < S/T <0.7 The drawdown power for P-4 impeller has a minimum value at D/T=0.33 and for D/T=0.4 and above the power is very high. HE-3 dr (open full item for complete abstract)

MS, University of Cincinnati, 2024, Engineering and Applied Science: Aerospace Engineering

This study underlines the impact of the flow structures on the internal flow field through shape-transitioning ducts with global favorable pressure gradients and local adverse pressure gradients, local to the shape-transitioning geometries. Results are evaluated for convergence apropos of acquisition frequency. This thesis presents preliminary results of flow structure measurement by introducing the structures with a cylindrical bluff body in the cross flow. Structure transport through the two duct configurations studied includes the free jet of a convergent nozzle and through a shape-transitioning nozzle. Particle Image Velocimetry (PIV) was employed in data acquisition considering its substantial spatiotemporal resolution necessary. Findings show that the free jet results are characterized by high-velocity jets, detached velocity deficit region at the tailing edge of the cylinder, and strong velocity gradients due to the shear layers formed between the wake, the jets, and the ambient. On the contrary, flow through the shape transitioning or favorable pressure gradient (FPG) nozzle reflects a well-behaved flow with a low-velocity region attached to the cylinder in most cases. The outcome difference primarily stems from the velocity experienced at the cylinder in each case. An examination of convergence, considering the acquiring frequency of the flow field data, unveiled a weighty impact of acquisition frequency on the results of turbulent flow fields. The ensemble average of the results based on the mathematical computation using analytical methods in the time domain revealed an overall comparable trend in results with notable distinctions in the near wake region. Convergence dependence of results on flow essence emerged with a comparison of the running averages at a point within and outside the wake. In conclusion, it was established that a smaller subset of image pairs drawn from a universal set is ample for effectively capturing the physics of the flow (open full item for complete abstract)

Master of Science, The Ohio State University, 2024, Mechanical Engineering

For the past 30 years engineering students at The Center for Automotive Research have been designing, building and racing electric vehicles on the Bonneville Salt Flats. Over the past 2 years, Buckeye Current, a student electric motorcycle team at Ohio State, has focused its efforts on developing a land speed racing (LSR) motorcycle for the under 150kg weight category for the Federation of International Motorcycles (FIM)n LSR records. This document begins with a high level development of the Buckeye Current RW-5 motorcycle and follows with a focus on the powertrain development. The document concludes with a review of the results to date and the future work remaining on the RW-5. The Buckeye Current motorcycles are named RW, in honor of Ryan Williams a former team member who passed away due to a motorcycle accident. The 5 stands for the motorcycle being in the fifth series of bikes the team has produced.

Master of Science in Mechanical Engineering, Cleveland State University, 2024, Washkewicz College of Engineering

Turbochargers significantly enhance engine efficiency and performance by increasing the amount of air entering the combustion chamber, leading to more complete fuel combustion and higher power output. Vibration analysis is a critical component in the maintenance and operational efficiency of turbochargers. Using finite element modal analysis, this study investigates the impact of material selection, unbalanced mass, and bearings on the vibration behavior of turbochargers. Three materials—titanium, stainless steel, and aluminum—were evaluated. The critical speeds are also calculated. The results suggest that using a high-stiffness material for the rotor, combined with a lightweight compressor and turbine wheel, can reduce vibration amplitude. The study highlights the significant influence of unbalanced mass due to turbochargers' high rotational speeds, which exceed 100,000 rpm, and their lightweight construction. Additionally, the research compares the performance of floating ring bearings and roller element bearings, focusing on stiffness and damping ratio. While roller element bearings demonstrate lower vibration amplitude, considerations such as bearing heating and lifespan are essential for optimal bearing selection. The findings provide preliminary insights for improving turbocharger performance through strategic material and component choices, thereby contributing to the overall advancement of engine technology.

Doctor of Philosophy, The Ohio State University, 2024, Mathematics

In this work, we study two problems in mathematical ecology. These problems are formulated as partial differential equations of reaction-diffusion type. In the first part of this work, we study the persistence of a single species or two species in a bounded domain subject to diffusive movement, environmental drift and boundary loss. These populations are described by a reaction-diffusion equation describing single- and two-species population dynamics. For the case of a single species, we establish the existence of the critical domain size, and analyze its dependence on the diffusion rate and rate of loss at each boundary point. We also consider the competition between two species which differ only in their dispersal rates. If the diffusion rates of both species are sufficiently large, we show that one species must exclude the other, and provide conditions under which the faster (or the slower) species will prevail. In the second part of this work, we study the spreading speed of a predator population that is expanding its range. Specifically, we consider a diffusive Lotka-Volterra system describing the interaction of a predator species and a prey species. Motivated by the effect of global climate change, it is imposed that the efficiency with which predators convert prey to offspring is described by a function whose profile is fixed in the moving frame x - c_1t. By applying the Hamilton-Jacobi approach, we completely determine the asymptotic spreading speed of the predator in the case that the conversion efficiency is monotonically increasing with arbitrary value of c_1 > 0. When the conversion efficiency is monotonically decreasing, we determine the spreading speed if the speed c_1 > 0 of the moving frame is sufficiently fast or slow.

Doctor of Philosophy, The Ohio State University, 2024, Mechanical Engineering

In this dissertation, a series of experiments were carried out to investigate the auto-ignition process of transient fuel jets and sprays issuing into high-temperature, environments. Novel high-speed imaging and laser diagnostic techniques were developed and applied to characterize mixing and turbulent flow conditions prior to and at the onset of ignition. In addition, this research examines the topology and dynamics of ignition kernels as they grow and transition into a stable flame. Research was carried out primarily in canonical atmospheric pressure experiments, but a new high-pressure spray test facility is developed in this work with preliminary measurements presented, demonstrating new experimental capabilities. Specific contributions of this dissertation include: (1) characterization of the transient mixing processes of variable-density atmospheric pressure jets both before and after ignition, (2) determination of the most probable mixing and turbulent flow conditions leading to local auto-ignition, (3) statistical evaluation of the dynamic growth and transport of ignition kernels, (4) construction and characterization of a novel high-pressure, high temperature spray and combustion facility, and (5) demonstration of high-speed mixture fraction measurements in non-reacting and reacting sprays at realistic thermodynamic conditions. First, a series of transient gas-phase fuel jets issuing into a high-temperature, vitiated environment at atmospheric pressure was investigated. A well-known jet-into-hot coflow configuration was utilized with the addition of a fast-acting solenoid valves to achieve pulsed fuel injection in an environment with well-defined boundary conditions. Four test conditions were studied to examine the effects of variations in jet Reynolds number, the fuel mixture composition, and coflow temperature. High-speed laser Rayleigh scattering (LRS) was performed at 10 kHz to measure the mixture fraction and temperature fields from fuel injection (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2024, Evolution, Ecology and Organismal Biology

Great and Lesser Prairie-Chickens are part of the genus Tympanuchus, who are known for their rapid foot-stomping behavior that creates a non-vocal drumming noise and their bright bare-part ornaments with ultraviolet reflectance. Both of these non-vocal components are prominent during their courtship displays along with other morphology and vocal traits. Females and other males may use multiple male signals from their display to assess multiple components of the male quality for mate choice and competition purposes. The central theme of this work is to investigate two non-vocal signals under the mechanisms of sexual selection intersexual mate choice and intrasexual competition. Signals are usually only considered under one of the mechanisms, typically intersexual mate choice or their impacts on social behavior has not been considered under any context. In Chapter 2, we investigated if foot-stomping could be integral in the communication of both the Greater and Lesser Prairie-Chicken, by using high-speed video cameras and recorders. We found that foot-stomping rate and duration increased with females' presences and only foot-stomping rate differ between the two species with Greater Prairie-Chickens having a higher rate than Lesser Prairie-Chickens. Since we used high-speed videos, we were able to collect simple kinematic measurements and found that both species are lifting their feet up higher when stomping when females are present. Since there was a difference in foot-stomping features when females were present/absent, in chapter 3 we investigated whether foot-stomping would increase the likelihood of a male to successfully mate, by using discrete choice modeling in Lesser Prairie-Chickens only. We added foot-stomping traits (rate and duration) with other behavioral, morphological, territorial, and color variables to run the discrete choice model. We found males increased their likelihood of successfully mating if they had a larger comb, increased aggressive behavior (open full item for complete abstract)

PHD, Kent State University, 2024, College of Education, Health and Human Services / School of Health Sciences

The present study sought to determine if high-intensity interval training (HIIT) at normobaric hypoxia (NH) alters measures of executive function, perceived mental exertion (RPE) and recovery (RPR), and hemodynamics. Nine individuals completed a HIIT intervention within a randomized condition (sea level; low NH: 900m; moderate NH: 2500m; high NH: 4300m). Measures of executive function were assessed after ten minutes of rest (Rest 1), 40 minutes of acclimation to NH (Rest 2), and 10 minutes following the HIIT (Post). Additionally, RPE and RPR were assessed at Rest 1, Rest 2, during active recovery following the first and last bout of HIIT (AR 1 and AR 6), and Post. Finally, measures of hemodynamics were assessed at Rest 1, Rest 2, AR 1, AR 6, and Post. Selective attention and processing speed were faster following HIIT. Additionally, both mental and physical RPE were augmented following HIIT. Following acclimation to the environment, heart rate (HR), systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP), as well as rate pressure product (RPP) were increased at moderate and high NH. Finally, following HIIT, HR, SBP, MAP, pulse pressure, and RPP were augmented. Collectively, this study suggests NH does not influence executive function, RPE or RPR, however it does impact hemodynamics. Additionally, performing HIIT does seem to alter such measures.

Doctor of Philosophy, The Ohio State University, 2024, Aerospace Engineering

Fluid-Structure Interactions (FSI) are a quintessential multi-disciplinary challenge, where the flowfield is influenced by the structure, and structural deformation is induced by the flow pressure. Computational and experimental research thrusts often seek to answer specific problems for specific configurations, offering observational answers to relatively complex problems. While there is a large body of work on FSI as a whole, the specific coupling mechanisms between the fluid and structural surface in the context of turbulent boundary layers (TBLs) in supersonic flows is an under-explored area of study. This dissertation details progress addressing this gap through cooperative consideration of high-fidelity simulations, classical semi-empirical models, analysis of the governing equations, and data-driven models. Large-Eddy Simulations (LES) of TBLs with static deformations are compared against classical semi-empirical models to characterize applicability to statically deformed surfaces for predicting loads transmitted from the boundary layer to the structure. Additionally, analysis of the governing equations, in conjunction with data-driven modeling, is used to extract a coherent link between structural deformation and the onset of local flow separations. Finally, a parametric study is carried out using Reynolds-Average Navier-Stokes (RANS) and Kriging surrogates to assess the impact of statically deformed surfaces on a downstream ramp. LES indicates that for a variety of deformations sized on the order of the incoming boundary layer, localized flow separation can develop. This leads to important flow modifications that are not readily captured with low-fidelity or semi-empirical models. Motivated by this, a first-order link between local flow separation and structural deformation parameters is established using the Momentum Integral Equation (MIE) combined with data-driven analysis. The curvature of the surface is identified as the dominant structural param (open full item for complete abstract)

Master of Arts, The Ohio State University, 2023, East Asian Languages and Literatures

Travel methods are always evolving to become faster, more efficient and user friendly. 2007 was the year that Taiwan entered their own ‘Era of High-Speed' with the opening of the High-Speed Rail line stretching from Taipei to Kaohsiung, shortening the commute from four to just two hours. This new transportation method allowed travelers an efficient mode of travel that can be used for business or pleasure. This paper assesses riders' satisfaction with Taiwan's HSR system, and highlights comparison with other forms of travel. Participants completed a survey detailing aspects of the HSR system and how big of a role it plays in their daily lives. A total of 74 surveys were collected, out of the participants, 69 are Taiwanese and 5 are from countries outside of Taiwan, including China, Japan, Indonesia, New Zealand and the Netherlands. In summary, participants see the system as a useful transportation option though more often opt for other forms of self-managed travel like motorcycles and cars and choose HSR when selecting from a range of public transportation options. On average, participants ride the HSR from 1 to 12 times a year. Expense plays a major role in choosing transportation and the HSR is not the cheapest form of travel in Taiwan, especially in the context of short-distance travel. Though minimal, having access to the HSR system has a positive impact on participants' lives. When asked how they would prefer to travel for long distance, such as from the north to the south of the island, they choose the HSR. 人們的旅行方式總是在不斷地在發展著，變得更快、更效率、更方便。2007年，臺灣開啓了“高速時代”。臺灣高鐵運營之後，乘客從臺北市到高雄市的乘坐時長只需要兩個小時左右，比之前的時長減少了兩個小時。這種新型有效的運輸方式大大地便利了乘客的商務或休閑旅行。爲了深入認識與瞭解臺灣高鐵對人民生活所產生的影響，本論文設計了一份重點關注乘客體驗與感受的關於臺灣高鐵的問卷調查。從所回收的74份調查問卷來看，參與者普遍認爲臺灣高鐵有實用價值。然而，令人感到好奇的是，參與問卷調查的人的出行方式仍然偏向個人主動掌握的自駕汽車或者機車，只是在使用公共交通作長途旅行時高鐵成爲首選。據統計，參與問卷的本地人總共69位，平均每年乘坐高鐵的次數最多達到12次，最少也有1次。乘坐高鐵的費用是影響人們是否選擇乘坐的主要原因之一，這是因爲臺灣高鐵的票價并不便宜。特別是短途旅行，乘坐高鐵并不是最經濟實惠的交通方式。不過就長途旅行而言，高鐵的優勢就吸引了大部分人。參與問卷的外來旅行者總共5位，來自中國大陸、日本、印尼、紐西蘭與荷蘭。不過，是否 (open full item for complete abstract)