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Full-Text Articles in Mechanical Engineering

Performance And Stability Of Cacl2·6h2o-Based Phase Change Materials, Joshua Charles Jan 2019

Performance And Stability Of Cacl2·6h2o-Based Phase Change Materials, Joshua Charles

Theses and Dissertations

Thermal energy storage is receiving increased attention as the world transitions away from fossil fuels and seeks to improve the efficiency of existing energy production systems. While higher-temperature thermal energy storage has received the majority of attention in the field, thermal energy storage at temperatures close to ambient conditions may also have some practical applications. Hydrated salt phase change materials (PCMs) store thermal energy in this temperature range and can have high gravimetric and volumetric energy storage capacities while having a very low cost. Despite the benefits of these salts, they generally suffer from supercooling, phase segregation during cycling, and ...


Modeling And Analyzing A Patch Of Human Red Blood Cell By Coarse-Grained Particle Method, Orhan Kaya Jan 2019

Modeling And Analyzing A Patch Of Human Red Blood Cell By Coarse-Grained Particle Method, Orhan Kaya

Theses and Dissertations

This thesis consists of three sections. First, some background information and theories about the erythrocyte membrane are provided. Second, a coarse-grained molecular dynamics model for a patch of erythrocyte membrane is built up. Third, the mechanical responses of the patch of red blood cells to diffusion and diffusivity, tension, rupture, and shear-induced pore area are analyzed.The patch of erythrocyte membrane is validated by modeling diffusivity and determining the diffusion coefficient constant. Then, the patch of the coarse-grained erythrocyte membrane is stretched uniformly until rupture. The critical stress/strain from simulation match with those obtained in experiments in laser optical ...


Efficient Modeling Of Latent Thermal Energy Storage Systems For Optimal Design And Operational Research, Chunjian Pan Jan 2019

Efficient Modeling Of Latent Thermal Energy Storage Systems For Optimal Design And Operational Research, Chunjian Pan

Theses and Dissertations

As a booming economy drives the need for more electricity, demands on freshwater for thermoelectric power generation also grow. Facing the limited freshwater resources, alternative dry cooling technologies such as air cooled condensers (ACCs) that reduce water consumption are becoming more prevalent. However, the performance of air ACCs is seriously deteriorated at ambient temperature. To address this challenge, a novel application of a Phase Change Material (PCM) based cooling system for supplementary cooling of ACCs is proposed. One of the engineering challenges that prevent the commercial application of latent thermal energy storage (LTES) systems is the lack of computationally efficient ...


Analysis Of Movement Of A 3t3 Cell With A Lamellipodium On A Substrate With Variable Rigidity, Alan Wopperer Jan 2019

Analysis Of Movement Of A 3t3 Cell With A Lamellipodium On A Substrate With Variable Rigidity, Alan Wopperer

Theses and Dissertations

Live cells move in the body in response to physiological and mechanical stimuli. Cells move using lamellipodium which extend beyond the leading edge of the cell. This lamellipodium is part of the cytoskeleton of the cell which pulls the cell forward in cell migration. It is observed that cells will move directionally depending on the stiffness of the substrate the cell comes into contact with. It is hypothesized that cells probe their environment to test the stiffness of their substrate. As a cell comes into contact with a substrate, the resulting force is dependent on how rigid or soft the ...


Computational Study Of Water Desalination Using Forward Osmosis, Ahmed Mohammed Alshwairekh Jan 2019

Computational Study Of Water Desalination Using Forward Osmosis, Ahmed Mohammed Alshwairekh

Theses and Dissertations

Forward Osmosis is a natural phenomenon that takes places across a semi-permeable membrane when there is a concentration difference across the membrane. Pure water permeates to the highly concentrated channel until the concentration across the membrane equilibrates. In water desalination applications, the same principle is applied. Spiral-wound membrane, flat sheet, or hollow fiber module are typical configurations in forward osmosis desalination modules. The application of water desalination using forward osmosis requires the existence of two channels separated by a suitable forward osmosis membrane. Sea or Brackish water is introduced in one side while the other side has a suitable draw ...


An Investigation Of Micro And Nanoscale Molding For Biomedical Applications, Ali A. Rajhi Jan 2019

An Investigation Of Micro And Nanoscale Molding For Biomedical Applications, Ali A. Rajhi

Theses and Dissertations

In the last decade, there has been rapid advancement of micro and nano manufacturing. Microinjection molding is a cost-effective fabrication technique that can fulfill the requirements of many medical applications. Despite the many advancements of microin


Computational Study Of Water Desalination Using Direct Contact Membrane Distillation, Anas Mohammed Alwatban Jan 2019

Computational Study Of Water Desalination Using Direct Contact Membrane Distillation, Anas Mohammed Alwatban

Theses and Dissertations

Computational fluid dynamics simulations were conducted to study the unit performance of direct contact membrane distillation for seawater desalination process in three-dimensional modules. A parametric study was conducted to assess the effects of the mem


An Investigation Of Enhanced Additive Manufacturing Incorporating Spatial Performance Property Control Throughout Printed Products, Alaauldeen Ali Duhduh Jan 2019

An Investigation Of Enhanced Additive Manufacturing Incorporating Spatial Performance Property Control Throughout Printed Products, Alaauldeen Ali Duhduh

Theses and Dissertations

The overall objective of this research is to investigate and develop a novel additive manufacturing technique that enables additive manufacturing to make products with customizable and gradient properties to match the consumer’s needs. This research inten


Energy Harvesting Devices Operating Near Free Surface, Bashar Hassan Attiya Jan 2019

Energy Harvesting Devices Operating Near Free Surface, Bashar Hassan Attiya

Theses and Dissertations

Water energy harvesting devices operate near surfaces in natural flow settings. The complex flow features such as flow separation and reattachment, wake instabilities, turbulent structures, and vortex shedding may lead to complicated loading on the struct


Fixed Bed Reactor Design For Thermochemical Energy Storage Using Ca(Oh)2 /Cao, Qasim Ranjha Aug 2018

Fixed Bed Reactor Design For Thermochemical Energy Storage Using Ca(Oh)2 /Cao, Qasim Ranjha

Theses and Dissertations

Thermochemical energy storage (TCES) is an attractive mode of storing the solar energy in the form of heat to be used with concentrated solar power (CSP) plants. Thermal energy is stored/released using a reverse endothermic/ exothermic reaction. TCES offers clear advantages over the other thermal energy storage (TES) options with sensible heat storage (SHS) and latent heat storage (LHS) in terms of energy density, storage time and the temperature range for thermal energy storage. However, this technique of storing the solar power at higher temperatures is still at laboratory or pilot scale, and researchers are trying to develop viable ...


Computational Study Of Desalination By Membranes, Mustafa Usta Aug 2018

Computational Study Of Desalination By Membranes, Mustafa Usta

Theses and Dissertations

Water desalination by membranes constitutes the majority of the low-quality water purication systems that extends across many different techniques. This study considers transport phenomena in reverse osmosis (RO) and vacuum membrane distillation (VMD) modules using computational techniques. Reverse osmosis is a pressure-driven separation method using semi-permeable membranes featuring nanoporous structures. Vacuum membrane distillation is another emerging separation method relying on the temperature difference across the microporous hydrophobic membranes.The membrane separation process intrinsically gives rise to temperature polarization (TP) and concentration polarization (CP) which could be severe limitations in these systems. To eliminate these polarizations and increase the module performance ...


Large Eddy Simulations Of Ventilated Micro-Hydrokinetic Turbine And Pump-Turbines, Cosan Daskiran Aug 2018

Large Eddy Simulations Of Ventilated Micro-Hydrokinetic Turbine And Pump-Turbines, Cosan Daskiran

Theses and Dissertations

Large eddy simulations of ventilated hydrokinetic turbine and pump-turbine are conducted. The mathematical modeling of oxygen dissolution and the flow model employed were validated by comparing predicted dissolved oxygen concentration against reported experimental measurements. A parametric study is performed to investigate the influence of interfacial forces, surface tension and bubble breakage and coalescence terms. It is demonstrated that aeration via hydrokinetic turbines can be used to improve the dissolved oxygen level in rivers for better water quality. It is also shown that aeration can effectively be achieved via the pump-turbine system to provide the desired dissolved oxygen level for the ...


Computational Study Of Free Jets Emanating From Circular And Lobed Orifice-Lattice Boltzmann Method, Yang Chen Aug 2018

Computational Study Of Free Jets Emanating From Circular And Lobed Orifice-Lattice Boltzmann Method, Yang Chen

Theses and Dissertations

The Lattice Boltzmann method is an effective computational fluid dynamics tool to study complex flows. Unlike conventional numerical schemes based on discretization of macroscopic continuum equations, the Lattice Boltzmann method is based on particles and mesoscopic kinetic equations. Single-Relaxation Time Lattice Boltzmann Method (SRTLBM) with Smagorinsky LES model is applied to simulate high Reynolds number jet flows of single and multiphase flows emanating. The multi-block approach is implemented to refine the mesh when the high resolution is needed in the region around the core jet. An 2nd order accurate interface treatment between neighboring blocks is derived to satisfy the conservation ...


The Mechanical Performance And Microstructure Development Of Laser Beam Welds And Post Weld Heat Treatment Of Ti 1023 Alloy, Meng Fu Huang Aug 2018

The Mechanical Performance And Microstructure Development Of Laser Beam Welds And Post Weld Heat Treatment Of Ti 1023 Alloy, Meng Fu Huang

Theses and Dissertations

Titanium alloys are widely used in the aerospace industry. For example, most components of the Boeing 777 landing gear are made of the Ti-10V-2Fe-3Al (Ti1023) alloy due to its lighweight and superior mechanical strength. In addition, because Titanium is chemicaly active element, when jointing the Ti alloy components, the laser beam welding (LBW) has been selected for avoiding the eventual contaminations and narrowing the heat affected zone by the presence of its protected atmosphere and low heat input. However, there is a lack of reported research results about welded Ti1023 alloy, particularly laser beam welding. Therefore, the microstructure and mechanical ...


Shape Control Of A Spatial Cable, Bo Tian May 2018

Shape Control Of A Spatial Cable, Bo Tian

Theses and Dissertations

Unmanned Aerial Vehicles (UAVs) have been widely used in scientific, industrial and military applications. Rotorcrafts, such as quadcopters, are agile and versatile in their applications. However one of the biggest challenges with such UAVs is their limited battery life that make the flight time for a typical UAVs limited to twenty to thirty minutes for most practical purposes. A solution to this problem lies in the use of cables that tether the UAV to a power outlet for constant power supply. However, the cable needs to be controlled effectively in order to avoid obstacles or other UAVs. In this thesis ...


A Topological Approach To Workspace And Motion Planning For A Cable-Controlled Robot In Cluttered Environments, Xiaolong Wang May 2018

A Topological Approach To Workspace And Motion Planning For A Cable-Controlled Robot In Cluttered Environments, Xiaolong Wang

Theses and Dissertations

There is a rising demand for multiple-cable controlled robots in stadiums or warehouses due to its low cost, longer operation time, and higher safety standards. In a cluttered environment the cables can wrap around obstacles. Careful choice needs to be made for the initial cable congurations to ensure that the workspace of the robot is optimized. The presence of cables makes it imperative to consider the homotopy classes of the cables both in the design and motion planning problems. In this thesis we study the problem of workspace planning for multiple-cable controlled robots in an environment with polygonal obstacles. This ...


Virtual Structural Analysis Of Bone Fracture Healing From Low-Dose Clinical Ct Scans, Peter Schwarzenberg May 2018

Virtual Structural Analysis Of Bone Fracture Healing From Low-Dose Clinical Ct Scans, Peter Schwarzenberg

Theses and Dissertations

Bone fractures often heal by forming a soft external bridge called a callus, which gradually hardens over time and restores the structural stiffness of the bone. In clinical studies focused on bone healing, healing progress is usually tracked using subjective assessments such as pain and mobility scores, qualitative observations of callus on X-rays, and incidence of complications such as implant fatigue failure. This data can be highly variable, leading to study designs that require very large multi-center trials with thousands of cases to detect differences between groups.Accordingly, the purpose of this thesis is to propose a new technique for ...


High Speed Wear Of Gallium Nitride, Zeyuan Tian May 2018

High Speed Wear Of Gallium Nitride, Zeyuan Tian

Theses and Dissertations

This thesis observes the tribological properties of GaN at relatively high sliding speeds. We choose a model for a pin-on-disk and unit direction rotate sliding experiments. To fulfill that we assemble a new high speed tribometer and completed some successful tests. In the results of these tests, we can find several interesting tribological properties (coefficient of friction and wear rate) of GaN in relatively high speed and get some reliable information when the GaN sliding under some specific conditions. The results are compared to former tests on GaN in Lehigh tribology lab, and it is proved that the c-plane of ...


Simulation And Optimal Integration Of A Heat Recovery Steam Generator With Solar Thermal Energy, Tianjun Han May 2018

Simulation And Optimal Integration Of A Heat Recovery Steam Generator With Solar Thermal Energy, Tianjun Han

Theses and Dissertations

With the increasing industrial manufacturing, commercial activities and better living conditions of world population, the consumption of electricity increases steadily. However, the world consumption of fossil fuels, which is the traditional source of electricity, is being reduced due to the impact of air pollution caused by the burning of fossil fuels.The integration of the Combined Cycle (CC) power plant with solar energy have recently been regarded as a good choice to mitigate high consumption of fossil fuels for a better environment for the reason that solar collectors can be coupled with the steam cycle side of CC power plant ...


Vortex Gust Interactions With Oscillating Joukowski Airfoil, Huansheng Chen May 2018

Vortex Gust Interactions With Oscillating Joukowski Airfoil, Huansheng Chen

Theses and Dissertations

The dynamic interactions between a line vortex and a Joukowski airfoil in harmonic motion are determined analytically and simulated numerically. The equations of vortex motion and the fluid forces on the airfoil are derived from two-dimensional inviscid potential flow theory for fixed and heaving airfoil configurations, and the continuous shedding of vorticity from the trailing edge is modelled by the emended Brown and Michael equation. Special attention is paid to limiting cases of flat airfoils that are either stationary or under prescribed harmonic motions. This work extends beyond these restrictions to include the effects of airfoil thickness and camber on ...


Effects Of Free-Stream Turbulence On Tidal Turbine Blade Performance And Wake, Angela Marie Lawrence May 2018

Effects Of Free-Stream Turbulence On Tidal Turbine Blade Performance And Wake, Angela Marie Lawrence

Theses and Dissertations

Tidal turbines operate inflow conditions with elevated levels of free-stream turbulence (FST) that affect the loads acting on components, which in turn affects the performance. The current work focuses on the use of controlled laboratory experiments to investigate the effects of free-stream turbulence on an SG-6043 turbine blade section. Elevated levels of FST are generated using an active grid generator at turbulence intensities (Ti) varying between 1.5-18%. It was observed that elevated levels of FST increased the coefficient of lift and caused a subsequent delay in flow separation. In addition, the coefficient of drag also increases at high angles ...


Investigation Of Elastoplastic Ratchetting Behavior Of Stainless Steel 316 Under Cyclic Uniaxial Asymmetric Loading At Room Temperature, Sirui Li May 2018

Investigation Of Elastoplastic Ratchetting Behavior Of Stainless Steel 316 Under Cyclic Uniaxial Asymmetric Loading At Room Temperature, Sirui Li

Theses and Dissertations

This work investigates, both experimentally and computationally the cyclic behavior of stainless steel 316 under uniaxial loading at room temperature. Elastoplastic investigations of SS 316 are important in the development of an understanding of the possible behavior and their contribution to the material performance under cyclic loading. Cyclic plasticity can occur in an SS 316 component or structure depending on the loading conditions. Therefore, it is vital that the cyclic behavior of SS 316 is recognized and understood. In particular SS316 cylindrical rods specimens were tested under uniaxial cyclic loading. The experimental results show that ratchetting behavior regimes exist under ...


Design And Manufacturing Of A High Performance Indoor Quadcopter, Guangyi Liu May 2018

Design And Manufacturing Of A High Performance Indoor Quadcopter, Guangyi Liu

Theses and Dissertations

In DCDS (Distributed Control and Dynamical Systems) laboratory, we are using quadcopter flying inside the building with motion capture system. In the quadcopter base, we are designing a new flight controller which has a high-speed processor and fast Wi-Fi communication. And the price is affordable in case of crashes during the research.The IMU used on the quadcopter is MPU6050 and HMC5883L magnetometer, they provide accurate Euler angle, angular velocity and heading at 200Hz. The controller used for attitude is cascade PID controller which controls the angle and the angular velocity at the same time, it’s robust and reliable ...


A Design Proposal For A Novel Gun-Launched Unmanned Aerial System, Douglas Bahr Rumbaugh, Jr. May 2018

A Design Proposal For A Novel Gun-Launched Unmanned Aerial System, Douglas Bahr Rumbaugh, Jr.

Theses and Dissertations

A proposed design for a gun-launched, unmanned aerial system (GLUAS) is presented, along with experimental data pertaining to the characterization of said design, and specifically targeted towards improving its aerodynamics through an examination of planform shape and wing flexibility.The proposed design consists of a deployable wing micro-aerial vehicle (MAV) that can fit inside of a 60mm mortar shell. The wings consist of 5 individual segments on each side, which stack on top of one another within the body, and are deployed by a torsion spring and an interlocking system of gears and bosses. These wings form a roughly semi-circular ...


Roughness Based Passive Control Of Transition To Galloping Of A Circular Cylinder Undergoing Vortex Induced Vibrations, Kumar Swagat May 2018

Roughness Based Passive Control Of Transition To Galloping Of A Circular Cylinder Undergoing Vortex Induced Vibrations, Kumar Swagat

Theses and Dissertations

Flow induced motion (FIM) is a naturally occurring fluid-structure interaction phenomenon, typically considered harmful to a wide variety of engineering structures. As a result, the majority of research in the field has been geared towards mitigating the occurrence of FIM. In 2005, Michael Bernitsas at the University of Michigan identified the energy harvesting potential of FIM’s, triggering a new line of research that instead focuses on augmenting it. Previous work by our group had tested the effectiveness of strips attached to the surface of a circular cylinder in augmenting FIM modes such as vortex induced vibrations (VIV) and galloping ...


Numerical Simulations Of Perforated Nozzle Inlets For Ramjets, Chuwei Chen Jan 2018

Numerical Simulations Of Perforated Nozzle Inlets For Ramjets, Chuwei Chen

Theses and Dissertations

Computational fluid dynamics simulations of supersonic flows through perforated and non-perforated nozzles are conducted. The primary objective of this thesis is to examine the influence of perforations in the convergent section of the nozzle on the spatial and temporal characteristics of the supersonic flows inside and outside the nozzle. The perforated nozzle might be utilized as supersonic inlet diffuser for high-speed flight engines, like ramjet, to reduce huge total pressure loss at starting process. The nozzle design is crucial for overall design of these systems, and the solution investigated here enjoys a high degree of interest for over 50 years ...


Free Swimming Bio-Inspired Hydrofoils In Unsteady Ground Effect, Jackson Heath Cochran-Carney Jan 2018

Free Swimming Bio-Inspired Hydrofoils In Unsteady Ground Effect, Jackson Heath Cochran-Carney

Theses and Dissertations

A free-swimming potential flow analysis of unsteady ground effect is conductedfor self-propelled, two-dimensional hydrofoils via a method of images. The foilsundergo a pure pitching motion about their leading edge, and the positionsof the body in the stream-wise and cross-stream directions are determinedby the equations of motion of the body. It is shown that the unconstrainedswimmer is attracted to a time-averaged position that is mediated by the flowinteraction with the ground. The robustness of this fluid-mediated equilibriumposition is probed by varying the non-dimensional mass, initial conditionsand kinematic parameters of motion. Comparisons to the foils fixed-motioncounterpart are also made to pinpoint the ...


Mechanoregulation Modeling Of Bone Healing In Realistic Fracture Geometries, Tianyi Ren Jan 2018

Mechanoregulation Modeling Of Bone Healing In Realistic Fracture Geometries, Tianyi Ren

Theses and Dissertations

One of the unique properties of fracture healing is that bones heal by producing new tissues that eventually become indistinguishable from the original ones in the pre-injury state, through the process of tissue differentiation. This process is fundamentally controlled by the mechanical conditions at the fracture site, particularly mechanical strain. Numerical models with strain-based fuzzy logic rules have been successfully applied to simulate bone healing in response to local mechanical stimuli for simple axisymmetric fracture geometries. However, these simplified models were not designed to replicate in vivo observations such as delays in healing with torsional instability or anticipated differences in ...


Design, Fabrication And Characterization Of Graded Transition Joints, Jonathan Galler Jan 2018

Design, Fabrication And Characterization Of Graded Transition Joints, Jonathan Galler

Theses and Dissertations

Carbon diffusion in dissimilar metal welds (DMWs) at elevated temperatures leads to a microstructure that is susceptible to premature failure. Graded transition joints (GTJs) can potentially provide a viable replacement to prolong the service life of these components. In the current investigation, the use of thermodynamic modeling was used to identify candidate alloys that reduce the chemical potential gradient, which is the driving force for carbon diffusion. Additionally, kinetic modeling was used to determine an optimal grade length for a graded transition joint to further reduce the extent of carbon diffusion. A graded transition joint was fabricated using three candidate ...


Stability And Dynamic Properties Of Tip Vortices Shed From Flexible Rotors Of Floating Offshore Wind Turbines, Steven Noel Rodriguez Jan 2018

Stability And Dynamic Properties Of Tip Vortices Shed From Flexible Rotors Of Floating Offshore Wind Turbines, Steven Noel Rodriguez

Theses and Dissertations

Floating offshore wind turbines exhibit unique near-wake characteristics due to ocean wave-induced rigid body motion of their rotor. The unique near-wake properties of this wind turbine are studied numerically as a coupled fluid-structure interaction (aeroelastic) phenomenon. The near-wake aerodynamics are modeleld in a Lagrangian sense by the lifting-line free-vortex wake method, and the dynamic rotor-blade structural deformations are described by the beam theory of spinning structures. The aerodynamic and structural domains are strongly coupled using a relaxation and subiteration scheme at each time step. This aeroelastic framework is believed to be the first of its kind with regards to its ...