Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Aerospace Engineering (4)
- Applied Mechanics (3)
- Biomedical Engineering and Bioengineering (3)
- Biomechanics and Biotransport (2)
- Civil and Environmental Engineering (2)
-
- Electrical and Computer Engineering (2)
- Materials Science and Engineering (2)
- Nanoscience and Nanotechnology (2)
- Physical Sciences and Mathematics (2)
- Acoustics, Dynamics, and Controls (1)
- Architectural Engineering (1)
- Architecture (1)
- Artificial Intelligence and Robotics (1)
- Bioresource and Agricultural Engineering (1)
- Civil Engineering (1)
- Computer Sciences (1)
- Energy Systems (1)
- Environmental Engineering (1)
- Industrial Engineering (1)
- Meteorology (1)
- Nuclear Engineering (1)
- Oceanography and Atmospheric Sciences and Meteorology (1)
- Operations Research, Systems Engineering and Industrial Engineering (1)
Articles 1 - 28 of 28
Full-Text Articles in Mechanical Engineering
Freezing-Induced Deformation Of Biomaterials In Cryomedicine, Altug Ozcelikkale
Freezing-Induced Deformation Of Biomaterials In Cryomedicine, Altug Ozcelikkale
Open Access Dissertations
Cryomedicine utilizes low temperature treatments of biological proteins, cells and tissues for cryopreservation, materials processing and cryotherapy. Lack of proper understanding of cryodamage that occurs during these applications remains to be the primary bottleneck for development of successful tissue cryopreservation and cryosurgery procedures. An engineering approach based on a view of biological systems as functional biomaterials can help identify, predict and control the primary cryodamage mechanisms by developing an understanding of underlying freezing-induced biophysical processes. In particular, freezing constitutes the main structural/mechanical origin of cryodamage and results in significant deformation of biomaterials at multiple length scales. Understanding of these freezing-induced …
Well-Posedness And Convergence Of Cfd Two-Fluid Model For Bubbly Flows, Avinash Vaidheeswaran
Well-Posedness And Convergence Of Cfd Two-Fluid Model For Bubbly Flows, Avinash Vaidheeswaran
Open Access Dissertations
The current research is focused on developing a well-posed multidimensional CFD two-fluid model (TFM) for bubbly flows. Two-phase flows exhibit a wide range of local flow instabilities such as Kelvin-Helmholtz, Rayleigh-Taylor, plume and jet instabilities. They arise due to the density difference and/or the relative velocity between the two phases. A physically correct TFM is essential to model these instabilities. However, this is not the case with the TFMs in numerical codes, which can be shown to have complex eigenvalues due to incompleteness and hence are ill-posed as initial value problems. A common approach to regularize an incomplete TFM is …
A Three Constituent Mixture Theory Model Of Cutaneous And Subcutaneous Tissue In The Context Of Neonatal Pressure Ulcer Etiology And Prevention, Anne Dye Zakrajsek
A Three Constituent Mixture Theory Model Of Cutaneous And Subcutaneous Tissue In The Context Of Neonatal Pressure Ulcer Etiology And Prevention, Anne Dye Zakrajsek
Open Access Dissertations
Localized ischemia, impaired interstitial fluid flow, and sustained mechanical loading of cells have all been hypothesized as mechanisms of pressure ulcer (PrU) etiology. Time-varying loading has experimentally been shown to increase fluid flow in human skin in vivo. Towards the design of prophylactic protocols and treatment modalities for PrU management there is a need for an analytical model to investigate the local fluid flow characteristics of skin tissue under time-varying loading. In this study, a triphasic mixture theory model with constituents of extracellular matrix, interstitial fluid, and blood was calibrated and validated and used to investigate stress and fluid velocity …
Modeling Person-To-Person Contaminant Transport In Enclosed Environments, Chun Chen
Modeling Person-To-Person Contaminant Transport In Enclosed Environments, Chun Chen
Open Access Dissertations
It is essential to predict person-to-person contaminant transport in enclosed environments to improve air distribution design and reduce the infection risk from airborne infectious diseases. This study aims to improve and accelerate the simulation of person-to-person contaminant transport in enclosed environments. ^ This investigation first conducted experimental measurements of person-to-person contaminant transport in an office mockup and the first-class cabin of a functional MD-82 aircraft. The experimental data of steady-state airflow, temperature, and gas contaminant concentration fields obtained in the office were used to validate the steady-state computational fluid dynamics (CFD) models. In the aircraft cabin, the transient particle concentrations …
Large Scale Modeling, Model Reduction And Control Design For A Real-Time Mechatronic System, Qiong Li
Large Scale Modeling, Model Reduction And Control Design For A Real-Time Mechatronic System, Qiong Li
Open Access Dissertations
Mechatronics is the synergistic integration of the techniques from mechanical engineering, electrical engineering and information technology, which influences each other mutually. As a multidisciplinary domain, mechatronics is more than mechanical or electronics, and the mechatronic systems are always composed of a number of subsystems with various controllers. From this point of view, a lot of such systems can be defined as large scale system. The key element of such systems is integration. Modeling of mechatronic system is a very important step in developing control design of such products, so as to simulate and analyze their dynamic responses for control design, …
Control Oriented Concentrating Solar Power (Csp) Plant Model And Its Applications, Qi Luo
Control Oriented Concentrating Solar Power (Csp) Plant Model And Its Applications, Qi Luo
Open Access Dissertations
Solar receivers in concentrating solar thermal power plants (CSP) undergo over 10,000 start-ups and shutdowns, and over 25,000 rapid rate of change in temperature on receivers due to cloud transients resulting in performance degradation and material fatigue in their expected lifetime of over 30 years. The research proposes to develop a three-level controller that uses multi-input-multi-output (MIMO) control technology to minimize the effect of these disturbances, improve plant performance, and extend plant life. The controller can be readily installed on any vendor supplied state-of-the-art control hardware.^ We propose a three-level controller architecture using multi-input-multi-output (MIMO) control for CSP plants that …
Computational Valve Plate Design, Paul K. Kalbfleisch
Computational Valve Plate Design, Paul K. Kalbfleisch
Open Access Theses
Axial piston machines are widely used in many industries for their designs compactness, flexibility in power transfer, variable flow rate, and high efficiencies as compared to their manufacturing costs. One important component of all axial piston machines that is a very influential on the performance of the unit is the valve plate. The aim of this research is to develop a design methodology that is general enough to design all types of valve plates and the simple enough not to require advanced technical knowledge from the user. A new style of valve plate designs has been developed that comprehensively considers …
Characterization Of Wake Effects And Loading Status Of Wind Turbine Arrays Under Different Inflow Conditions, Xiangyu Gao
Characterization Of Wake Effects And Loading Status Of Wind Turbine Arrays Under Different Inflow Conditions, Xiangyu Gao
Open Access Theses
The objective of the present work is to improve the accuracy of Actuator Line Modeling (ALM) in predicting the unsteady aerodynamic loadings on turbine blades and turbine wake by assessing different methods used to determine the relative velocity between the rotating blades and wind. ALM is incorporated into a Large Eddy Simulation (LES) solver in OpenFOAM (Open Field Operations and Manipulations). The aerodynamic loadings are validated by experiment results from National Renewable Energy Laboratory (NREL). Turbine wakes are validated by predictions of large eddy simulation using exact 3D blade geometries from a two-blade NREL Phase VI turbine. Three different relative …
Drop Volume Modulation Via Modulated Contact Angle In Inkject Systems, Aaron Fulton
Drop Volume Modulation Via Modulated Contact Angle In Inkject Systems, Aaron Fulton
Open Access Theses
To date, there are limited options in the ability to adjust feature sizes when inkjet printing. The reduction of nozzle size has been the primary method by which smaller features are created. Prior attempts to reduce feature sizes have all come with some restriction or another, as they are only accessible on certain systems, are difficult to manufacture, tune, cause clogging, etc. Few attempts to create droplets of smaller radii than that of the nozzle from which they are produced have been successful. Additionally, many fluids cannot be jetted whatsoever. Existing methods pertain largely to piezoelectric inkjet printing and time …
Bayesian Global Optimization Approach To The Oil Well Placement Problem With Quantified Uncertainties, Zengyi Dou
Bayesian Global Optimization Approach To The Oil Well Placement Problem With Quantified Uncertainties, Zengyi Dou
Open Access Theses
The oil well placement problem is vital part of secondary oil production. Since the calculation of the net present value (NPV) of an investment depends on the solution of expensive partial differential equations that require tremendous computational resources, traditional methods are doomed to fail. The problem becomes exceedingly more difficult when we take into account the uncertainties in the oil price as well as in the ground permeability. In this study, we formulate the oil well placement problem as a global optimization problem that depends on the output of a finite volume solver for the two-phase immiscible flow (water-oil). Then, …
Characterization And Evaluation Of Head Impact Sensors And Varsity Football Helmets, Brian R. Cummiskey
Characterization And Evaluation Of Head Impact Sensors And Varsity Football Helmets, Brian R. Cummiskey
Open Access Theses
An increased understanding of the effects of brain injury in recent years has led to greater attention being given to the topic. A desire to investigate the causal agents of these injuries in athletes has led to the development and use of several devices that track head impacts as well as improving helmet technology to protect players from said impacts. In order to determine which devices are able to best measure head impacts, a Hybrid III headform was used to quantify the accuracy for translational and angular accelerations. Testing was performed by means of administering impacts to a helmet on …
Modeling And Analysis Of A Resonant Nanosystem, Scott L. Calvert
Modeling And Analysis Of A Resonant Nanosystem, Scott L. Calvert
Open Access Theses
The majority of investigations into nanoelectromechanical resonators focus on a single area of the resonator's function. This focus varies from the development of a model for a beam's vibration, to the modeling of electrostatic forces, to a qualitative explanation of experimentally-obtained currents. Despite these efforts, there remains a gap between these works, and the level of sophistication needed to truly design nanoresonant systems for efficient commercial use. Towards this end, a comprehensive system model for both a nanobeam resonator and its related experimental setup is proposed. Furthermore, a simulation arrangement is suggested as a method for facilitating the study of …
Numerical Characterization Of Convective Heat Transfer Of Low-Rise Buildings, Ranchi Chen
Numerical Characterization Of Convective Heat Transfer Of Low-Rise Buildings, Ranchi Chen
Open Access Theses
The convective heat transfer coefficient (CHTC) is an important parameter to evaluate the efficiency of building-integrated photovoltaic/Thermal (PV/T) system and the energy exchange within the turbulent atmospheric boundary layer. Reynolds-average Navier-Stokes approach has been frequently used to predict the CHTC at the surface of low rise roof but incapable of predicting transient behavior of separation, reattachment and recirculation both on the windward and leeward surface. However, Large Eddy Simulation approach (LES) could provide accurate flow field and temperature field around the low rise building. ^ The current study uses Large Eddy Simulation with Smagorinsky-Lily model and the Shear Stress Transport …
Smart V-Belt, Kyle J. Mosier
Smart V-Belt, Kyle J. Mosier
Open Access Theses
The purpose of this research was to develop a method for detecting premature failure in a v-belt using capacitance and resistance readings. Another goal of the research was to detect tension values on the belt using the same readings. Materials of current belts and possible materials for a prototype belt were tested. Materials were chosen, and prototype belts were built. Pulley system configurations were developed and built. Sections of the belt designs were tested for capacitance and resistance before and after various methods of damage. Capacitance was chosen as the better sensing method. Certain layered belt configurations and sheave configurations …
Numerical Simulation And Characterization Of Jet Flows In Indoor Environments, Zhu Shi
Numerical Simulation And Characterization Of Jet Flows In Indoor Environments, Zhu Shi
Open Access Theses
Jet flows are prevalent in indoor environment and other engineering applications. Typical examples in indoor environment include the flow discharged from personal ventilation systems, and the jet exhaled through breathing or coughing. When there is density (or temperature) difference between the jet and surroundings, jet flow becomes stratified jet. Due to its complication, stratified jet flow is difficult to model, especially in the developing or transitional region of the flow. Studying stratified jet flows is of great significance for understanding the mixing dynamics of jet and ambient environment. This is particularly important for optimizing indoor environment design, or obtaining accurate …
Machining As A Mechanical Property Test Revisited, David L. Smith
Machining As A Mechanical Property Test Revisited, David L. Smith
Open Access Theses
There is much need for data on mechanical behavior of metals at high strains and strain rates. This need is dictated by modeling of processes like forming and machining, wherein the material in the deformation zone is subjected to severe deformation conditions atypical of conventional material property tests such as tension and torsion. Accurate flow stress data is an essential input for robust prediction of process outputs. Similar requirements arise from applications in high speed ballistic penetration and design of materials for armor. Since the deformation zone in cutting of metals is characterized by unique and extreme combinations of strain, …
An Experimental Investigation Of A Premixed Laminar Flame Using Tunable Diode Laser And Quantitative Imaging Of Radiation Intensity, Weichao Wang
Open Access Theses
Simultaneous CO concentration and temperature measurements using Tunable Diode Laser Absorption Spectroscopy (TDLAS) are reported in this study. Ro-vibrational transitions of CO, R(27) and R(6) are used for probing absorbance profiles. Premixed ethylene-air flat flame on a McKenna burner is used for creating combustion gaseous products at equivalence ratio 0.83 to 1.82. Nitrogen shroud flow is used for preventing air mixing. Both Direction Absorption (DA) and Wavelength Modulation Spectroscopy (WMS) experiments are conducted. Experimental results are compared with literature and simulation using CHEMKIN and chemical equilibrium. Reasonable agreements are achieved between experiment and simulation. The CO detection limit is determined …
Understanding Mechanical Environment Changes And Biological Responses To Canine Retraction Using T-Loop, Feifei Jiang
Understanding Mechanical Environment Changes And Biological Responses To Canine Retraction Using T-Loop, Feifei Jiang
Open Access Dissertations
Jiang, Feifei. Ph.D., Purdue University, May 2015. Understanding Mechanical Environment Changes and Biological Responses to Canine Retraction Using T-loop. Major Professors: Jie Chen, School of Engineering and Technology, Anil Bajaj, School of Mechanical Engineering. Predictability of tooth displacement in response to specific orthodontic load system directly links to the quality and effectiveness of the treatment. The key questions are how the tooth's environment changes in response to the orthodontic load and how the biological tissues respond clinically. The objectives of this study are to determine the mechanical environment (ME) changes and to quantify the biological tissues' response. Eighteen (18) patients …
Fully Electronic Method Of Measuring Post-Release Gap And Gradient/Residual Stress Of A Mems Cantilever, Andrew Stephen Kovacs
Fully Electronic Method Of Measuring Post-Release Gap And Gradient/Residual Stress Of A Mems Cantilever, Andrew Stephen Kovacs
Open Access Dissertations
Smartphones and other wireless devices have become ubiquitous over the past decade, and the RF front-end inside of them has become more complex and disproportionately consumes more power compared to other components. Micro-electromechanical systems (MEMS) have a huge potential to reduce these problems while simultaneously offering superior performance compared to current leading-edge technology. However, MEMS technology has difficulty transitioning from the lab to large-scale manufacturing due to the unpredictability of device lifetime and manufacturability issues. This can be mitigated by investigating how critical material or physical parameters (gap, stress, Young's modulus, material thickness, etc.) vary from manufacturing uncertainties and how …
An Experimental Study On The Effects Of Blade Row Interactions On Aerodynamic Loss Mechanisms In A Multistage Compressor, Natalie Rochelle Smith
An Experimental Study On The Effects Of Blade Row Interactions On Aerodynamic Loss Mechanisms In A Multistage Compressor, Natalie Rochelle Smith
Open Access Dissertations
While the gas turbine engine has existed for nearly 80 years, much of the complex aerodynamics which governs compressor performance is still not well understood. The unsteady flow field consists of periodic blade row interactions from the wakes and potential fields of each blade and vane. Vane clocking is the relative circumferential indexing of adjacent vane rows with the same vane count, and it is one method to change blade row interactions. Though the potential of performance benefits with vane clocking is known, the driving flow physics have yet to be identified. ^ This research examines the effects of blade …
Modeling On Single-Sided Wind-Driven Natural Ventilation, Haojie Wang
Modeling On Single-Sided Wind-Driven Natural Ventilation, Haojie Wang
Open Access Dissertations
Buildings use 40% of the total primary energy in the United States, with a significant part of this energy being used for ventilation and cooling. Despite the large amount of energy used in buildings, reports have shown that the indoor air quality (IAQ) and thermal comfort are not satisfactory. The lowered productivity due to the bad IAQ could cause $125 billion loss per year and the sick building syndromes could cause $32 billion direct healthcare costs. Most of the problems related to IAQ are caused by insufficient fresh outdoor air supply or lack of maintenance with traditional mechanical ventilation systems. …
Real-Time Rss-Based Indoor Navigation For Autonomous Uav Flight, Sangjun Lee
Real-Time Rss-Based Indoor Navigation For Autonomous Uav Flight, Sangjun Lee
Open Access Theses
Navigation for the autonomous flight of Unmanned Aerial Vehicles (UAVs) in an indoor space has attracted much attention recently. One of the main goals of an indoor navigation system is developing an alternative method to obtain position information that can replace or complement the global positioning system. While much research has focused on vision-based indoor navigation systems, this paper aims to develop a Received Signal Strength (RSS)-based navigation system, which is a more cost effective alternative. Then, the position and attitude of a UAV can be computed by the fusion of RSS measurements and measurements from the onboard inertial measurement …
Optimizing Electrode Thickness And Material For Laser-Induced Electrothermal Flow, Jian Wei Khor
Optimizing Electrode Thickness And Material For Laser-Induced Electrothermal Flow, Jian Wei Khor
Open Access Theses
In this article, the material dependence of electrothermal flow is studied to optimize an optoelectric particle manipulation technique called Rapid Electrokinetic Patterning (REP). REP utilizes a heat source to produce temperature gradients, which, in this study, are induced by the application of a 1064 nm cw laser. The simultaneous application of an uniform AC electric field assemble colloids on the surface of an electrode that can be moved by translating the laser. The temperature gradients produced from the heat source are crucial in REP as the higher the temperature gradient the faster the electrothermal flow. Thus, optimization of temperature gradients …
Improving Product Design Phase For Engineer To Order (Eto) Product With Knowledge Base Engineering (Kbe), Hanhdung Thi Dinh
Improving Product Design Phase For Engineer To Order (Eto) Product With Knowledge Base Engineering (Kbe), Hanhdung Thi Dinh
Open Access Theses
In industry currently Computer Aided Design (CAD) is an important tool for the modification, analysis, or optimization of the 3D virtual environment that replicates the physical product. CAD software is an efficient and reliable tool. However, as globalization increases customer demands, this process needs to be faster and more efficient to accommodate changing product design situations, especially for Engineer-to- Order (ETO) products. ^ The traditional method of product design process is to operate CAD software without argumentation. Design engineers create CAD prototypes and drawings based on available knowledge and information which comes from engineering experts, company standards, industrial practices as …
Asymptotic Modelling Of A Thermopiezoelastic Anisotropic Smart Plate, Yufei Long
Asymptotic Modelling Of A Thermopiezoelastic Anisotropic Smart Plate, Yufei Long
Open Access Theses
Motivated by the requirement of modelling for space flexible reflectors as well as other applications of plate structures in engineering, a general anisotropic laminated thin plate model and a monoclinic Reissner-Mindlin plate model with thermal deformation, two-way coupled piezoelectric effect and pyroelectric effect is constructed using the variational asymptotic method, without any ad hoc assumptions. Total potential energy contains strain energy, electric potential energy and energy caused by temperature change. Three-dimensional strain field is built based on the concept of warping function and decomposition of the rotation tensor. The feature of small thickness and large in-plane dimension of plate structure …
Delamination Of C/Pekk I-Beam Using Virtual Crack Closure Technique And Cohesive Zone Method, Greeshma Ramakrishna
Delamination Of C/Pekk I-Beam Using Virtual Crack Closure Technique And Cohesive Zone Method, Greeshma Ramakrishna
Open Access Theses
A damage study is conducted on a carbon epoxy/PEKK (poly-ether-ketone-ketone) thermoplastic composite I-Beam, with a pre crack of 100 mm modeled between the top flange and the filler (butt joint between filler and web). This project is in collaboration with Fokker Aerostructures, Netherlands and is part of the Thermoplastic Primary Aircraft Structure innovation program (TAPAS). The C/PEKK I-Beam is modeled after a section of the Gulfstream G650 aircraft's centre beam, which was previously a carbon fiber/epoxy hat-stiffened skin construction. The objective of the thesis is to identify if the crack propagates in the I-Beam within the load range that act …
Design And Heat Transfer Analysis Of Accelerating Distributed Combustion System, Yashovardhan U. Wagh
Design And Heat Transfer Analysis Of Accelerating Distributed Combustion System, Yashovardhan U. Wagh
Open Access Theses
Over the past few decades, there has been a significant increase in greenhouse gases such as CO2, N2O, and CH4 produced from gas turbine engines. Keeping this in mind, current research work is being carried out for reducing NOx produced from combustors. The objective of this research is to determine the feasibility of Distributed Combustion Systems (DCS) for increasing efficiency and reducing NOx emissions. ^ A DCS has a main combustion zone (MCZ) where 90% of the fuel is burned and is followed by a secondary combustion zone (SCZ) in which jets carrying fuel are …
Structure-Thermal Coupling In Viscoelastic Material In Rubber Bushing Of Vehicle System, Zhengui Zhang
Structure-Thermal Coupling In Viscoelastic Material In Rubber Bushing Of Vehicle System, Zhengui Zhang
Open Access Dissertations
The objective of this research is to utilize the frequency-dependent viscoelastic material model and characterize the dynamic response of rubber bushing under external excitation. Furthermore, with appropriate modeling, two heat generation mechanisms of rubber bushing are explored and their thermal fields are investigated. Due to the nonlinear force-deflection relationship of the viscoelastic material, finding satisfactory mechanical properties of rubber components still poses a great challenge. However, industry nowadays is in urgent demand for precise finite element analysis (FEA) modeling of rubber components. For example, a proper constitutive relationship of rubber components is critical to providing a reliable and trustable simulation …