Mechanical Engineering Commons^™

Development Of Novel Models To Study Deep Brain Effects Of Cortical Transcranial Magnetic Stimulation, Farheen Syeda

Theses and Dissertations

Neurological disorders require varying types and degrees of treatments depending on the symptoms and underlying causes of the disease. Patients suffering from medication-refractory symptoms often undergo further treatment in the form of brain stimulation, e.g. electroconvulsive therapy (ECT), transcranial direct current stimulation (tDCS), deep brain stimulation (DBS), or transcranial magnetic stimulation (TMS). These treatments are popular and have been shown to relieve various symptoms for patients with neurological conditions. However, the underlying effects of the stimulation, and subsequently the causes of symptom-relief, are not very well understood. In particular, TMS is a non-invasive brain stimulation therapy which uses time-varying magnetic …

Development Mems Acoustic Emission Sensors, Adrian Enrique Avila Gomez

USF Tampa Graduate Theses and Dissertations

The purpose of this research is to develop MEMS based acoustic emission sensors for structural health monitoring. Acoustic emission (AE) is a well-established nondestructive testing technique that is typically used to monitor for fatigue cracks in structures, leaks in pressurized systems, damages in composite materials or impacts. This technology can offer a precise evaluation of structural conditions and allow identification of imminent failures or minor failures that can be addressed by planned maintenances routines. AE causes a burst of ultrasonic energy that is measured as high frequency surface vibrations (30 kHz to 1 MHz) generated by transient elastic waves that …

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 …

The Effect Of Bone And Ligament Morphology Of Ankle Joint Loading In The Neutral Position, Jinhyuk Kim

Mechanical & Aerospace Engineering Theses & Dissertations

Computational modeling of joints is used to investigate the effect of injuries, to plan surgeries, and to answer questions about joints that cannot be answered experimentally. Existing models of the ankle joint are moving toward being able to model specific patients, however, they do not include all of the anatomy (e.g., bones and/or ligaments) and have restrictive boundary conditions. These simplification in anatomy are made to minimize pre-processing and computation time. Because biomechanical modeling is increasingly focused on the implementation of patient specific cases, the effects of including more anatomical structures and determining how they affect the model results is …

Characterizing The Viscoelastic Behavior Of Pdms/Pdps Copolymers, Mark E. Small

Mechanical Engineering ETDs

Viscoelasticity is the property of materials that exhibits both viscous and elastic characteristics when undergoing deformation. In polymeric materials, the mechani- cal behavior is dominated by this viscoelastic phenomenon. Creating computational models for these materials can be quite complicated due to their frequency depen- dent and temperature dependent material properties. The research presented in this paper will use state of the art methods to fully develop a material model for a filled polydimethylsiloxane-polydiphenynlsiloxane (PDMS/PDPS) copolymer foam that has yet to be characterized. Mechanical properties of PDMS/PDPS copoly- mers are currently being studied to assess engineering performance, and to provide accurate …

The Influence Of Bmss On The Characterization And Modeling Of Series And Parallel Li-Ion Packs, Sandra Castano-Solis, Daniel Serrano-Jimenez, Lucia Gauchia, Javier Sanz

Michigan Tech Publications, Part 1

This work analyzes the effects of a BMS (battery management system) on the characterization and modeling of series and parallel connections of Li-ion cell packs. The Li-ion pack studied consists of four series modules connected in parallel. This pack has been characterized by means of charge, discharge and frequency tests. As a result of these tests, series and parallel influence on battery parameters have been determined. A model considering the effects of a BMS is established and compared with a model based on a single-cell approach. Experimental validations show that the single cell based approach gives poor results in comparison …

Real-Time Sensing Of Trust In Human-Machine Interactions, Wan-Lin Hu, Kumar Akash, Neera Jain, Tahira Reid

School of Mechanical Engineering Faculty Publications

Human trust in automation plays an important role in successful interactions between humans and machines. To design intelligent machines that can respond to changes in human trust, real-time sensing of trust level is needed. In this paper, we describe an empirical trust sensor model that maps psychophysiological measurements to human trust level. The use of psychophysiological measurements is motivated by their ability to capture a human's response in real time. An exhaustive feature set is considered, and a rigorous statistical approach is used to determine a reduced set of ten features. Multiple classification methods are considered for mapping the reduced …

Modeling Of Selective Laser Sintering/ Selective Laser Melting, Xuan Wang, Connor West

Industrial and Manufacturing Engineering

Selective laser sintering and selective laser melting are powder based additive manufacturing (AM) process that can rapidly manufacture parts with comparable mechanical properties to conventional manufacturing methods directly from digital files. However, the processing recipe development and design optimization of AM parts are often based on trial and error which erodes the benefit of AM. Modeling is a powerful tool to enable faster development cycle by significantly reducing the experimental efforts. In this paper we discussed the current status of selective laser sintering/melting modeling, in which the laser and powder interaction was studied to understand and predict the process and …

Models For The Residual Life Of Railroad Bearing Grease In Laboratory And Industry Applications, Douglas Timmer, Constantine Tarawneh, Robert Jones

Manufacturing & Industrial Engineering Faculty Publications

Adequate lubrication in railroad bearings is crucial to the safe operation of these components. An investigation of the residual life of railroad bearing grease was conducted in a laboratory setting. The data was collected using a split-split-plot design of experiments. The Oxidation Induction Time (OIT), which is the time required for the remaining antioxidants in a sample of grease to be consumed in a test, is the response variable for this study. Low values of OIT indicate small remaining amounts of antioxidants in the grease and thus small remaining residual life in the grease. OIT measurements were made using differential …

Turbulent Spray Combustion Modeling Using Direct Integration Of Chemistry And Flamelet Generated Manifolds, Ashraya Goyal

Wayne State University Theses

Turbulent spray combustion of n-dodecane was modeled at engine relevant conditions using various combustion models (Direct Integration of Chemistry and Flamelet Generated Manifolds) and turbulence models (Dynamic Structure Large Eddy Simulation and RNG Reynolds-Averaged Naiver-Stokes). A recently developed n-dodecane mechanism was utilized and the turbulent spray was simulated at various combustion chamber initial gas temperature and pressure conditions. Mesh with size of 31 microns was utilized to resolve small eddies around the spray. The pressure-based ignition delay, flame lift-off length, and spray and jet penetrations were studied and compared with experimental measurements. The Direct Integration of Chemistry and Flamelet Generated …

Statistical Shape Modeling To Quantify Variation In The Proximal Humeral Anatomy, Paul B. Sade Sr.

Electronic Theses and Dissertations

The fit of the humeral prosthesis to the intramedullary canal and the replication of the anatomic humeral head center are important factors in Total Shoulder Arthroplasty (TSA). The objective of this thesis was to develop a Statistical Shape Model (SSM) of the cortical and cancellous bone regions of the proximal humerus, and to assess potential shape differences with gender and ethnicity, with a goal of informing implant design. An SSM was used and Principal Component Analysis (PCA) was applied to data that represented both the cancellous and cortical humeral bone of 63 healthy subjects and cadavers. Anatomical measurements and PC …

Evaluating The Performance Of Passive Chilled Beams With Respect To Energy Efficiency And Thermal Comfort, Janghyun Kim

Open Access Dissertations

Existing modeling approaches for passive chilled beams determined from tests on individual chilled beams in a laboratory are not adequate for assessing overall energy usage and occupant comfort within building simulation programs. In addition, design guidelines for passive chilled beam systems are needed for identifying appropriate applications and optimal configurations. This thesis includes (i) extensive experimental studies for characterizing the performance of passive chilled beams, in both laboratory settings and in field studies, (ii) development of passive chilled beam performance prediction models, (iii) integration of these models into building simulation models/tools and (iv) use of building simulation for overall assessment …

Modeling And Control Of Fuel Cell-Battery Hybrid Energy Sources, Nima Lotfi

Doctoral Dissertations

"Environmental, political, and availability concerns regarding fossil fuels in recent decades have garnered substantial research and development in the area of alternative energy systems. Among various alternative energy systems, fuel cells and batteries have attracted significant attention both in academia and industry considering their superior performances and numerous advantages. In this dissertation, the modeling and control of these two electrochemical sources as the main constituents of fuel cell-battery hybrid energy sources are studied with ultimate goals of improving their performance, reducing their development and operational costs and consequently, easing their widespread commercialization. More specifically, Paper I provides a comprehensive background …

An Experimental Investigation Of The Effect Of Temperature And Space Velocity On The Performance Of A Cu-Zeolite Flow-Through Scr And A Scr Catalyst On A Dpf With And Without Pm Loading, Vaibhav Kadam

Dissertations, Master's Theses and Master's Reports

Abstract The heavy-duty diesel (HDD) engines use the diesel oxidation catalyst (DOC), catalyzed particulate filter (CPF) and urea injection based selective catalytic reduction (SCR) systems in sequential combination, to meet the US EPA 2010 PM and NOₓ emission standards. The SCR along with a NH₃ slip control catalyst (AMOX) offer NOₓ reduction >90 % with NH₃ slipHowever, there is a strong desire to further improve the NOₓ reduction performance of such systems, to meet the California Optional Low NOₓ Standard implemented since 2015. Integrating SCR functionality into a diesel particulate filter (DPF), by coating the SCR catalyst on the DPF, …

Modeling And Simulation Of Micro Electrical Discharge Machining Process, Bai Shao

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Micro parts and systems are playing crucial roles in the area of semiconductor, biomedical device, micro fluid devices, automotive, aerospace and so forth. Micro manufacturing is one of the most important technologies in realizing miniaturization. Compared to other micro manufacturing methods, micro-EDM is drawing lots of attention due to its ability to machine complex 3D parts regardless of the hardness of the workpiece material.

Micro-EDM is the cumulative result of numerous single discharges; therefore, it is crucial to understand the single discharge material removal process in micro-EDM. However, due to the stochastic nature and complex process mechanism, micro-EDM, including its …

Oxidation Process Of H 2 O /Uv For Cod Reduction Of Wastewater From Soybean Tofu Production, Komala Pontas, Abrar Muslim

Makara Journal of Technology

Chemical Oxygen Demand (COD) reduction of wastewater from soybean tofu production was studied by conducting advanced oxidation process (AOP) using hydrogen peroxide with UV radiation catalysts in a closed cylindrical glass reactor. The hydroxyl radical (*OH) concentration from H2O2 decomposition was modeled, and exponential trends were found for the *OH concentration over radiation time and operation temperature. As a result, it was found that the maximal *OH concentration was 0.209 mol L-1 at 240 minutes and 50 °C. The *OH concentration exponentially increased following rise in operation temperature. The H2O2/UV AOP application reduced COD concentration to approximately 42.41% from 10,545 …

Systems Modeling And Economic Analysis Of Photovoltaic (Pv) Powered Water Pumping Brackish Water Desalination For Agriculture, Michael A. Jones

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The objective of this study was to determine the economic viability of solar powered water pumping and desalination systems for agriculture. Growing global demand for agricultural production has put increased pressure on limited freshwater resources in various locations around the word. Many areas have low quality groundwater resources that have not been utilized for agriculture due to limited availability to electricity, high operational costs of diesel generators and the economics associated with water pumping and processing. Reverse osmosis is a desalination technology that removes salts and other minerals from low-quality water, making it fit for drinking or irrigation. Reduced costs …

Modeling Of Environmentally Assisted Fatigue Crack Growth Behavior, Sree Phani Chandar Reddy

Dissertations

The formation of fatigue cracks and their propagation due to cyclic loading in metals have been a concern for more than hundred years. Since fatigue failure were first reported by the railroad industry in 1840s, tremendous progress has been achieved in understanding fatigue behavior of metals. But fatigue damage is still a concern due to its complex dependency on various environmental variable like humidity, temperature, time and corrosive environment. Although numerous theories and models have been proposed in the past, the effects of environment on fatigue crack growth (FCG) is not completely understood. This dissertation aims to shed light on …

Creep And Shrinkage Behavior Of Fly Ash Based Geopolymer Concrete, Md Rashedul Islam

Doctoral Dissertations

The manuscript presented herein is based on the investigation of the short and long term properties of fly ash based geopolymer concrete (GPC) and their link to fly ash characteristics. Fly ash (FA) exhibits a significantly different particle morphology, which impacts the mechanical properties of the resulting GPC and typically contains impurities that fluctuate from one FA source to another. A key contribution of this research work is the capturing of the variability posed by the FA stockpile with a wide range of physical, chemical, and crystallographic characteristics as a source material to select the GPC mix design. In the …

Molecular Modeling Of Epon 862-Detda / Carbon Composites, Cameron Hadden

Dissertations, Master's Theses and Master's Reports - Open

The thermoset epoxy resin EPON 862, coupled with the DETDA hardening agent, are utilized as the polymer matrix component in many graphite (carbon fiber) composites. Because it is difficult to experimentally characterize the interfacial region, computational molecular modeling is a necessary tool for understanding the influence of the interfacial molecular structure on bulk-level material properties. The purpose of this research is to investigate the many possible variables that may influence the interfacial structure and the effect they will have on the mechanical behavior of the bulk level composite. Molecular models are established for EPON 862-DETDA polymer in the presence of …

Micro- And Macro-Scale Modeling Of Filter Aging: Effects Of Particle Poly-Dispersity And Fiber Cross-Sectional Shape, Ahmed M. Saleh

Theses and Dissertations

The goal of this study is to further advance the state of the art in developing self-sufficient methods to predict the performance of an aerosol filter. The simulation methods developed in this study are based on first principles and consequently, they do not rely on empirical correction factors. These simulation methods can be used to predict the instantaneous collection efficiency and pressure drop of a filter under dust-loading conditions. In the current study, 3-D micro- and macroscale CFD models are developed to simulate the service life of flat-sheet and pleated filters. These CFD micro- and macroscale models are also used …

Self-Assembly Kinetics Of Microscale Components: A Parametric Evaluation, Jose Miguel Carballo

USF Tampa Graduate Theses and Dissertations

The goal of the present work is to develop, and evaluate a parametric model of a basic microscale Self-Assembly (SA) interaction that provides scaling predictions of process rates as a function of key process variables. At the microscale, assembly by “grasp and release” is generally challenging. Recent research efforts have proposed adapting nanoscale self-assembly (SA) processes to the microscale. SA offers the potential for reduced equipment cost and increased throughput by harnessing attractive forces (most commonly, capillary) to spontaneously assemble components. However, there are challenges for implementing microscale SA as a commercial process. The existing lack of design tools prevents …

Oxygen Flux And Dielectric Response Study Of Mixed Ionic-Electronic Conducting (Miec) Heterogeneous Functional Materials, Fazle Rabbi

Theses and Dissertations

Dense mixed ionic-electronic conducting (MIEC) membranes consisting of ionic conductive perovskite-type and/or fluorite-type oxides and high electronic conductive spinel type oxides, at elevated temperature can play a useful role in a number of energy conversion related systems including the solid oxide fuel cell (SOFC), oxygen separation and permeation membranes, partial oxidization membrane reactors for natural gas processing, high temperature electrolysis cells, and others. This study will investigate the impact of different heterogeneous characteristics of dual phase ionic and electronic conductive oxygen separation membranes on their transport mechanisms, in an attempt to develop a foundation for the rational design of such …

Stress Corrosion Cracking In Polymer Matrix Glass Fiber Composites, Jonathan Kosak

Electronic Theses and Dissertations

With the use of Polymer Matrix Glass Fiber Composites ever expanding, understanding conditions that lead to failure before expected service life is of increasing importance. Stress Corrosion Cracking (SCC) has proven to be one such example of conditions found in use in high voltage transmission line applications that leads to brittle fracture of polymer matrix composites.

SCC has been proven to be the result of acid buildup on the lines due to corona discharges and water buildup. This acid leaches minerals from the fibers, leading to fracture at low loads and service life. In order to combat this problem, efforts …

A One-Dimensional Model Of A Closed-Loop Refrigeration Test Block For Centrifugal Compressors, Paul D. Gessler

Master's Theses (2009 -)

The increasingly competitive building equipment and control industry pushes manufacturers to continually improve the performance and efficiency of their products to develop and maintain a competitive edge. Compressor development is an expensive endeavor, but the cost and time required for testing can be minimized by developing a model of the compressor test block to predict its behavior with a given prototype compressor at specified operating conditions. This thesis presents a thermodynamic model of a hot gas bypass test block used to evaluate centrifugal compressor performance at a compressor development facility. The test block uses cooling towers to reject the heat …

Numerical Investigation Of Boiling In A Sealed Tank In Microgravity, Sonya Lynn Hylton

ETD Archive

NASA's missions in space depend on the storage of cryogenic fluids for fuel and for life support. During long-term storage, heat can leak into the cryogenic fluid tanks. Heat leaks can cause evaporation of the liquid, which pressurizes the tank. However, when the tanks are in a microgravity environment, with reduced natural convection, heat leaks can also create superheated regions in the liquid. This may lead to boiling, resulting in much greater pressure rises than evaporation at the interface between the liquid and vapor phases. Models for predicting the pressure rise are needed to aid in developing methods to control …

Design And Development Of Heterogenous Combustion Systems For Lean Burn Applications, Anthony Terracciano

Electronic Theses and Dissertations

Combustion with a high surface area continuous solid immersed within the flame, referred to as combustion in porous media, is an innovative approach to combustion as the solid within the flame acts as an internal regenerator distributing heat from the combustion byproducts to the upstream reactants. By including the solid structure, radiative energy extraction becomes viable, while the solid enables a vast extension of flammability limits compared to conventional flames, while offering dramatically reduced emissions of NOx and CO, and dramatically increased burning velocities. Efforts documented within are used for the development of a streamlined set of design principles, and …

Understanding Chassis Inputs From The Rear Suspension Of A Snowmobile, Jamie L. Kleinendorst

Dissertations, Master's Theses and Master's Reports - Open

Today’s snowmobile industry faces great challenges in the field of noise & vibration. The area of main concern is the pass-by noise restriction defined by the Society of Automotive Engineers (SAE) test standard J192, with a maximum sound pressure level of 78 dB(A) being required by many states and national parks. To continue meet or beat this requirement without effecting machine performance, a deeper understanding of the sound transfer paths is required. This thesis examines the transfer paths created by the tunnel, rear suspension, drive shaft, and rubber composite track, with the primary source being suspension input through the ground. …

The Effects Of Asymmetric Micro Ratchets On Pool Boiling Performance, Lance Austin Brumfield

LSU Doctoral Dissertations

Nucleate boiling is an attractive method for achieving high heat flux at low superheat temperatures. It is frequently used for industrial applications such as heat exchangers and is being considered to cool advanced central processing units (CPU) which produce heat fluxes on the order of 1 MW/m2 and are becoming increasingly less efficient to cool via forced conduction of air. The issue with implementing nucleate boiling as a cooling mechanism lies in the difficulty of quantifying the numerous and complex mechanisms which control the process. A comprehensive nucleate boiling model has yet to be formulated and will be required in …

Analysis Of A Dual Scissored-Pair,Variable-Speed, Control Moment Gyroscope Driven Spherical Robot, Richard Chase

Wayne State University Dissertations

The objective of this research is to compare barycenter offset based designs of spherical robots to control moment gyroscope (CMG) based designs in order to determine which approach is most effective. The first objective was to develop a list of current state of the art designs in order to gain an overall understanding of what the obstacles in this area of research were. The investigation showed that barycenter offset designs can produce a low, continuous output torque, whereas CMG based designs can usually only produce a high, momentary output torque. The second objective was to develop a CMG based design …