Mechanical Engineering Commons^™

Multi-Mesh Reduced-Order Basis Method For Finite Element Analysis, Ashkan Akbariyeh

Mechanical and Aerospace Engineering Dissertations - Archive

Reduced order modeling of differential equations parametrized over a parameter space can be used to accelerate optimization and parameter estimation problems. The method of snapshots or reduced order basis is well established among researchers as a tool to build reduced order models of ordinary differential equations. The reduced order basis method has been utilized for numerical solution of parametric PDE problems by researchers in recent years and has many advantages over response surface methods. The application of ROB to finite element analysis has been restricted to using a fixed mesh for snapshots. In this work, a new method is developed …

Thermal Measurement And Optimization Of Materials And Processes In A Li-Ion Cell, Vivek Vishwakarma

Mechanical and Aerospace Engineering Dissertations - Archive

Applications of Lithium-ion cells range from consumer electronics to electric cars because of their excellent electrochemical performance and energy density. However, a Li-ion cell also suffers from poor thermal transport characteristics, which reduces performance, causes overheating and thermal runaway. This work contributes towards thermal characterization of key Li-ion battery materials and identifies and improves the rate-limiting, material-level thermal conduction process in a Li-ion cell. Among the various materials within a Li-ion cell, the separator is expected to have the lowest thermal conductivity. In this work, we have carried out first-ever measurements of thermal conductivity and heat capacity of the separator …

Flexible-Continuum Robot For Bladder Tissue Diagnostics, Samson Abimbola Adejokun

Mechanical and Aerospace Engineering Theses - Archive

The aim of this thesis is to investigate and develop a robotic system capable of a transurethral palpation of any targeted area on the bladder interior wall tissue to determine the biomechanical properties of the tissue considering the urinary tract geometric constraints and to demonstrate the motion kinematics of such robot to achieve a desired robot pose normal to any localized region throughout the bladder workspace. Current technologies have, to varied degree of success, provide approximate, global diagnostics information to bladder tissue elasticity. However, no direct access qualitative methods to measure the bladder tissue properties are known. For this reason, …

Enhancing Indirect / Direct Evaporative Heat Exchanger In Data Center Cooling By Using Phase Change Material, Ahmed Ali Abuklam

Mechanical and Aerospace Engineering Theses - Archive

Electrical usage in data center continues to grow and recent projection estimate that it contributes 2% in the electricity use in the U.S. One method of controlling the electrical usage during cooling is to reduce or eliminate mechanical cooling; however, using indirect/direct evaporative (IDE) cooling system is starting to be quite popular. IDE has limitations and in this paper we will show how phase change material (PCM) can extend the cooling capacity of IDE. The PCM has been used for temperature control operations. Latent heat storage is one of the most efficient ways of storing thermal energy in PCM. The …

Cfd Simulation And Design Optimization To Improve Cooling Performance Of Open Compute ‘Big Sur’ Server, Mangesh Mohan Dhadve

Mechanical and Aerospace Engineering Theses - Archive

In recent years, there have been a phenomenal increase in Artificial Intelligence and Machine Learning that require data collection, mining and using data sets to teach computers certain things to learn, analyze image and speech recognition. Machine Learning tasks require a lot of computing power to carry out numerous calculations. Therefore, most servers are powered by Graphics Processing Units (GPUs) instead of traditional CPUs. GPUs provide more computational throughput per dollar spent than traditional CPUs. Open Compute Servers forum has introduced the state-of-the-art machine learning servers “Big Sur” recently. Big Sur unit consists of 4OU (OpenU) chassis housing eight NVIDIA …

Analysis Of Composite Structures With Curvature Under Temperature Environment, Muthu Ram Prabhu Elenchezhian

Mechanical and Aerospace Engineering Theses - Archive

Composite structures are frequently exposed to environments with change in temperatures during their service life. The thermal behaviours of the laminated composite structures are more pronounced than that of the structures made of isotropic materials. For the structures under thermal environment, extensive studies have been conducted to investigate the induced thermal stresses and deformation of composite laminated plates by linear/non-linear analysis and composite structures by finite element analysis. The main focus of this study is concentrated on development of an analytical method for analyzing composite thin shells and/or moderate curved beam structures under temperature environment. This includes the derivation of …

Finite Element Analysis On Hybrid Boron-Carbon Composites, Amruta Rupa Nemani

Mechanical and Aerospace Engineering Theses - Archive

Adaptability to different situations and the ease of combination makes composites one of the most extensively used materials in the engineering industries. One of the ways of managing properties of composites is hybridization of different fibers in one composite. This work merely focuses upon the analysis of effective stiffness of Hybrid materials which is carried out using Finite Element Method. A series of models were experimented in a sequence by imposing various conditions on each of them. Boron and Carbon fibers were used primarily for these experiments because of their better compatibility than other combinations of fibers. Due to the …

Thermal Modeling Of 3-Dimensionally Stacked Dram Memory, Ratnesh Raj

Mechanical and Aerospace Engineering Theses - Archive

A large fraction of energy consumed in modern microelectronic devices and systems is taken up by memory access operations, which is expected to cause significant temperature rise. Since memory access operations are very short this is expected to inherently be a transient thermal phenomenon. Despite the critical importance of thermal management in microelectronics, not much work exists on understanding the nature of thermal transport during memory access operations. In this work, a mathematical model to predict the transient temperature rise within a 3D layered memory chip is presented. Most heat-generating memory access processes occur over a short timescale for which …

Numerical Simulation Of Flow In Fluidic Valves In Rotating Detonation Engines, Nandini Gopalakrishnan

Mechanical and Aerospace Engineering Theses - Archive

Rotating detonation engines (RDE) have received considerable research attention in recent times for use in propulsion systems. The cycle frequency of operation of an RDE can be as high as 10,000 Hz. Conventional mechanical valves cannot operate at such high frequencies, leading to the need for propellant injectors or valves with no moving parts. A fluidic valve is such a valve and is the focus of this study. The valve consists of an orifice connected to a constant area plenum cavity which operates at constant pressure. The fluidic valve supplies propellants to the detonation tube through the orifice. Hydrogen – …

Experimental And Computational Study Of Multi-Level Cooling Systems At Elevated Coolant Temperatures In Data Centers, Manasa Sahini

Mechanical and Aerospace Engineering Dissertations - Archive

Data centers house a variety of compute, storage, network IT hardware where equipment reliability is of utmost importance. Heat generated by the IT equipment can substantially reduce its service life if T_(J,Max), maximum temperature that the microelectronic device tolerates to guarantee reliable operation, is exceeded. Hence, data center rooms are bound to maintain continuous conditioning of the cooling medium. This approach often results in over-provisioned cooling systems. In 2014, U.S. Data center electricity consumption is about 1.8% of the total electrical energy in the country. Hence, data center power and cooling have become significant issues facing the IT industry. The …

Prediction Of Process-Induced Defects By Ply-Drops In The Design Optimization Of A Complex Composite Laminate, Sitanshu Pandya

Mechanical and Aerospace Engineering Theses - Archive

The objective of this work is to characterize manufacturing process-induced warping defects due to ply drops in composite laminates to guide composite laminate design. Composite laminate optimization seeks weight efficient models, but the process can also generate complex ply geometry, which compounds the challenges of the already rigorous composite laminate manufacturing process. Increased design complexity enhances the likelihood of manufacturing process-induced defects like warping; therefore, it is important to predict such defects in the design phase to make the product more efficient yet producible and thereby avoid such defects. This work study is manufacturing process induced warpage in complex composite …

Dynamic Rating Of Overhead Transmission Lines Over Complex Terrain Using A Large-Eddy Simulation Paradigm, Tyler Phillips, Ray Deleon, Inanc Senocak

Mechanical and Biomedical Engineering Faculty Publications and Presentations

Dynamic Line Rating (DLR) enables rating of power line conductors using real-time weather conditions. Conductors are typically operated based on a conservative static rating that assumes worst case weather conditions to avoid line sagging to unsafe levels. Static ratings can cause unnecessary congestion on transmission lines. To address this potential issue, a simulation-based dynamic line rating approach is applied to an area with moderately complex terrain. A micro-scale wind solver — accelerated on multiple graphics processing units (GPUs) — is deployed to compute wind speed and direction in the vicinity of powerlines. The wind solver adopts the large-eddy simulation technique …

The Influence Of The Electrode Dimension On The Detection Sensitivity Of Electric Cell–Substrate Impedance Sensing (Ecis) And Its Mathematical Modeling, Xudong Zhang, William Wang, Anis Nurashikin Nordin, Fang Li, Sunghoon Jang, Ioana Voiculescu

Publications and Research

Detection sensitivity is a crucial criterion in the design and application of ECIS sensors. The influence of sensing electrode dimension on detection sensitivity is investigated in this paper. Eight types of ECIS sensors were fabricated, and their experimental results reveal that smaller-radius working electrodes generate more sensitive impedance shift to cell density change. Also, the smaller radius of working electrodes yield higher impedance values, which improves signal-to-noise ratio. In a range from 1.0 mm to 3.5 mm, the distance between the working and counter electrodes does not affect impedance measurements. However, the distance should be large enough to prevent the …

Development Of Empirical And Virtual Tools For The Study Of Bicycle Safety, Brent Kostich

Masters Theses

Bicycles have been used as a form of non-motorized transportation for several hundred years. Recently, their use in the transportation realm has been reinvigorated because of growing population densities and efforts to improve environmental sustainability. However, a large deterrent for public use of the bicycle is concern over its level of safety in the transportation environment. The goal of this thesis is to develop two complementary research tools that advance the study of bicycle safety factors.

First, an instrumented probe bicycle (IPB) is constructed from the ground up. The bicycle is outfitted with an array of sensors that are integrated …

Analysis Of Angles-Only Hybrid Space-Based/Ground-Based Approach For Geosynchronous Orbit Catalog Maintenance, Blythe A. Andrews

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Geosynchronous Equatorial Orbit (GEO) is critical to Earth communications, weather monitoring, and national defense. Orbit estimation of GEO objects is difficult due to physical constraints placed on ground-based tracking devices such as weather, object range, and tracking frequency restrictions. These constraints are commonly mitigated through the use of two-way signaling devices for cooperative GEO satellites. However, determining the position and velocity of uncooperative GEO satellites and/or objects is more challenging. The objective of this dissertation is to quantify the increased orbital accuracy of objects in the GEO catalog when the Air Force Space Command Space Surveillance Network (AFSPC SSN) is …

Realizing Structural Color Generation With Aluminum Plasmonic V-Groove Metasurfaces, W. Wang, D. Rosenmann, D. Czaplewski, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Piezoelectric Bistable Buckled Beam Energy Harvester., Brian Edward Allgeier

Electronic Theses and Dissertations

A novel energy harvesting device design is presented to be created via microfabrication techniques. Such devices have countless applications for powering low-current electrical devices, especially wireless sensors or transmitters. This micro-electromechanical system (MEMS) design utilizes the piezoelectric response of a bistable buckled beam to gather electrical energy via ambient vibrations. While many traditional piezoelectric energy harvesters (PEH) consist of simple cantilever beam geometries, this nonlinear design utilizes inertial effects of torsional lever arms to actuate a central buckled beam to snap between its two stable states; such an abrupt strain on the piezoelectric beam potentially produces a significantly increased electrical …

Atmospheric Microbial Community Sampling System For Varying Altitude Collection, Kenneth David Domingue

Masters Theses

The study of airborne microbial communities in the vertical atmosphere is an area of research in which very little data has been collected and analyzed. Developing a vehicle to house biological sampling equipment that collects, and mitigates contamination is required by a team of biology researchers to perform sampling of atmospheric microbial communities. This study uses a sampler box that is attached to aerostatic vehicles: zero pressure balloons and tethered balloon/kite structures. Zero pressure balloons are used for sampling at altitudes above 150 m above sea level, and tethered balloon/kite structures are used for sampling at 30 m and 150 …

Optimization Of Prosthetic Hands: Utilizing Modularity To Improve Grip Force, Grasp, And Versatility, Jordan William Harris

UNLV Theses, Dissertations, Professional Papers, and Capstones

It has been demonstrated that although many varieties of upper limb prosthetics exist, commercially available prosthetics are outdated and unsatisfactory. Ineffectiveness and limitations have led to some prosthesis wearers having to own multiple devices, whereas others have given up on them entirely. Even though ample research has been conducted to design and test new hand designs, the industry appears to rest in an overall stagnated state.

It was proposed here, that one problem with prosthetic research is an excess of variables involved in testing, and therefore the improper application of the scientific method. It seems that each time a research …

Meshless Method For Simulation Of Compressible Flow, Ebrahim Nabizadeh Shahrebabak

UNLV Theses, Dissertations, Professional Papers, and Capstones

In the present age, rapid development in computing technology and high speed supercomputers has made numerical analysis and computational simulation more practical than ever before for large and complex cases. Numerical simulations have also become an essential means for analyzing the engineering problems and the cases that experimental analysis is not practical. There are so many sophisticated and accurate numerical schemes, which do these simulations. The finite difference method (FDM) has been used to solve differential equation systems for decades. Additional numerical methods based on finite volume and finite element techniques are widely used in solving problems with complex geometry. …

An Economic Analysis Of Residential Photovoltaic Systems With And Without Energy Storage, Rodney Moses Kizito

Graduate Theses and Dissertations

Residential photovoltaic (PV) systems serve as a source of electricity generation that is separate from the traditional utilities. Investor investment into residential PV systems provides several financial benefits such as federal tax credit incentives for installation, net metering credit from excess generated electricity added back to the grid, and savings in price per kilowatt-hour (kWh) from the PV system generation versus the increasing conventional utility price per kWh. As much benefit as stand-alone PV systems present, the incorporation of energy storage yields even greater benefits. Energy storage (ES) is capable of storing unused PV provided energy from daytime periods of …

Biomechanical Testing Of An Exercise For Strengthening The Proximal Femur., Alyssa Osbourne

Electronic Theses and Dissertations

Based on the principles of cutting edge bone remodeling research, a unique therapeutic exercise device was designed specifically to improve bone quality at the most critical location of the proximal femur prone to fracture: the superior-lateral femoral neck where the fracture first initiates during a fall. The exercise/device is intended to work by inducing enough strain in the bone to stimulate the body’s natural bone remodeling mechanisms to increase bone density in the proximal femur and consequently prevent a fracture from arising if a fall to the side does occur.

In order to test the proposed exercise, experiments simulating the …

Thermoelectric System Modeling And Design, Buddhima Pasindu Gamarachchi

Boise State University Theses and Dissertations

Thermoelectric generators (TEGs) convert heat to electricity by way of the Seebeck effect. TEGs have no moving parts and are environmentally friendly and can be implemented with systems to recover waste heat. This work examines complete thermoelectric systems, which include the (TEG) and heat exchangers or heat sinks attached to the hot and cold sides of the TEG to maintain the required temperature difference across the TEG. A 1-D steady state model is developed to predict the performance of a TEG given the required temperatures and device dimensions. The model is first validated using a 3-D model and then is …

Characterization Of Lift And Drag On Two Dimensional Airfoils With And Without Sinusoidal Leading Edges, Gregorio I. Acosta

Theses and Dissertations

An experimental investigation was taken on a 63-021 NACA airfoil, to characterize lift and drag and how the effects of sinusoidal leading edges affect the aerodynamic properties. A theoretical model is also purposed by implementing a perturbation on thin-airfoil theory.

Two sets of airfoils were machined and tested inside a low-speed open circuit wind tunnel. Data from a pressure scanner and particle image velocity will give an insight of how the modified leading edges affect the aerodynamic properties. A Fourier series expansion was used to solve for the lifting-line model, by use of thin-airfoil theory and complex number theory.

Parametric Resonance Of A Repulsive Force Mems Electrostatic Mirror, Mehmet Ozdogan, Meysam Daeichin, Abdallah H. Ramini, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

We investigate the nonlinear dynamic behavior of an electrostatic MEMS mirror. The MEMS mirror is driven by repulsive force actuators, which avoid pull-in instability and enable large travel ranges. In parallel-plate actuators, the force on the structure is toward the substrate limiting the range of motion to the capacitor gap. Unlike parallel-plate, repulsive force actuators push the mirror away from the substrate not limiting the motion. The highly nonlinear nature of the repulsive force and the large motions create unique characteristics that dier from parallel-plate actuators. Repulsive force actuators show linear natural frequency hardening with increased DC voltages unlike parallel-plate …

Effect Of Multiphase Radiation On Coal Combustion In A Pulverized Coal Jet Flame, Bifen Wu, Somesh Roy, Xinyu Zhao, Michael F. Modest

Mechanical Engineering Faculty Research and Publications

The accurate modeling of coal combustion requires detailed radiative heat transfer models for both gaseous combustion products and solid coal particles. A multiphase Monte Carlo ray tracing (MCRT) radiation solver is developed in this work to simulate a laboratory-scale pulverized coal flame. The MCRT solver considers radiative interactions between coal particles and three major combustion products (CO₂, H₂O, and CO). A line-by-line spectral database for the gas phase and a size-dependent nongray correlation for the solid phase are employed to account for the nongray effects. The flame structure is significantly altered by considering nongray radiation and …

Phonon Dispersion And Relaxation Time In Uranium Dioxide, Dallin Parkinson

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Phonon dispersion branches are used to obtain an effective relaxation time to calculate thermal conductivity of Uranium Dioxide (UO₂). The method presented closely follows that of Deskins’ phonon-phonon interaction that uses a three-phonon process which satisfies momentum and energy conservation. All phonon branches including longitudinal acoustic, transverse acoustic, longitudinal optical and transverse optical are considered in the calculation of the relaxation time.

After one phonon is identified, a scan is initiated to test all phonon combinations that will satisfy the conservation equations. When the scan identifies a valid three-phonon combination a relaxation time is calculated for that combination. …

Visualization And 3d Printing Of A 3d Solar Tracker Model Using Mayavi And Pov-Ray, Aditya Mehra

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

In this work, we have created a realistic model of a solar tracker using Mayavi: 3D scientific data visualization and plotting in Python, Enthought Canopy:a comprehensive Python analysis environment and Persistence of Vision Ray Tracer, or POV-Ray, a ray tracing program which generates photo-realistic images from a text-based scene description, a model of the solar tracker was also 3D printed.

Facilitation Of Nanoscale Thermal Transport By Hydrogen Bonds, Lin Zhang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Thermal transport performance at the nanoscale and/or of biomaterials is essential to the success of many new technologies including nanoelectronics, biomedical devices, and various nanocomposites. Due to complicated microstructures and chemical bonding, thermal transport process in these materials has not been well understood yet. In terms of chemical bonding, it is well known that the strength of atomic bonding can significantly affect thermal transport across materials or across interfaces between materials. Given the intrinsic high strength of hydrogen bonds, this dissertation explores the role of hydrogen bonds in nanoscale thermal transport in various materials, and investigates novel material designs incorporating …

Heat Transfer Analysis Of Localized Heat-Treatment For Grade 91 Steel, Jacob D. Walker

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Many of the projects utilizing Grade 91 steel are large in scale, therefore it is necessary to assemble on site. The assembly of the major pieces often requires welding in the assembly; welding drastically changes the superior mechanical properties of Grade 91 steel that it was specifically developed for. Therefore, because of the adverse effects of welding on the mechanical properties of Grade 91, it is necessary to do a localized post weld heat treatment.

In this study a localized post weld heat treatment is used to gather experimental data. The data is then used to derive unknown heat transfer …