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2020

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Articles 1291 - 1307 of 1307

Full-Text Articles in Mechanical Engineering

Evaluation Of Control Strategies For Overhead Work Using Electromyography Of Rotator Cuff Muscles, Hossein Motabar Jan 2020

Evaluation Of Control Strategies For Overhead Work Using Electromyography Of Rotator Cuff Muscles, Hossein Motabar

Graduate Theses, Dissertations, and Problem Reports

Work-related musculoskeletal disorders (MSDs) of shoulder have a significant impact on overall health and economics in the industrialized nations. Rotator cuff is the most frequently injured region in the shoulder complex. Overhead work is considered as one of the most predominant causes of rotator cuff injuries. The workers in construction, automotive, and aerospace industries are routinely exposed to overhead exertions. Elimination of overhead work is nearly impossible due to various task and technology constraints. Therefore, appropriate intervention strategies based on the engineering and administrative controls opt to be used to prevent the hazardous impact of overhead exertions. The objective of …

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Sensitivity And Uncertainty Quantification Of Continuum And Stochastic Bond Dissociation Kinetics Based Cohesive Laws, Rishabh Awasthi Jan 2020

Sensitivity And Uncertainty Quantification Of Continuum And Stochastic Bond Dissociation Kinetics Based Cohesive Laws, Rishabh Awasthi

Dissertations, Master's Theses and Master's Reports

Polymeric adhesives are being extensively used to develop light weight and durable Composite Materials which are have been employed in automotive, aeronautical, medical industry. Polymeric adhesives undergo failure due to relative opening sliding of bonded interfaces which requires a need to characterize the fracture mechanism. Numerous experiments are conducted to predict the fracture response for Mode-I, II,III and numerical simulations are employed to inversely calibrate the material parameters governing the constitutive laws. Cohesive zone models are largely employed in fracture mechanics to predict failure of interfaces undergoing large plastic deformations. The objective of this report is to employ the cohesive …

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A Solar‐Driven Membrane‐Based Water Desalination/Purification System, Abdellah Shafieian Dastjerdi Jan 2020

A Solar‐Driven Membrane‐Based Water Desalination/Purification System, Abdellah Shafieian Dastjerdi

Theses: Doctorates and Masters

Lack of fresh water has turned into one of the major challenges of the world in the present century. Desalination of brackish or seawater has been proven to be one of the best solutions to cope with this global challenge. Among all the desalination methods, Membrane Distillation (MD) is well known as a cost effective and profitable technology for treating saline water. However, higher energy consumption compared to other separation techniques has been reported as MD’s main drawback. That is why the application of solar energy to provide the thermal energy requirement of MD modules has been the focal point …

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Microstructure And Mechanical Behavior Of Metastable Beta Type Titanium Alloys, Chirag Dhirajlal Rabadia Jan 2020

Microstructure And Mechanical Behavior Of Metastable Beta Type Titanium Alloys, Chirag Dhirajlal Rabadia

Theses: Doctorates and Masters

Current biomaterials such as stainless steel, Co-Cr alloys, commercially pure titanium and Ti-6Al- 4V either possess poor mechanical compatibility and/or produce toxic effects in the human body after several years of usage. Consequently, there is an enormous demand for long-lasting biomaterials which provide a better combination of mechanical, corrosion and biological properties. In addition to this, alloys used in high-strength applications possess either high-strength or large plasticity. However, a high-strength alloy should possess a better blend of both strength and plasticity when used in high-strength applications. Metastable β-titanium alloys are the best suited alloys for biomedical and high-strength applications because …

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The Optimum Design Of A Vacuum-Compatible Manipulator To Calibrate Space Based Ultraviolet Imagers, Jason L. Grillo Jan 2020

The Optimum Design Of A Vacuum-Compatible Manipulator To Calibrate Space Based Ultraviolet Imagers, Jason L. Grillo

Master's Theses

Recent discoveries in geospace science have necessitated the design of compact UV imaging instruments to make space-based observations from multiple vantage points. The miniaturized ultraviolet imager (MUVI) instrument from the Space Sciences Laboratory (SSL) at UC Berkeley is under development to facilitate such discoveries on a wider scale. This thesis documents the design, integration, and characterization of a vacuum compatible manipulator to calibrate the MUVI instrument inside the UV thermal vacuum chamber at SSL. Precision linear and rotation stages were implemented with custom mounting plates to achieve four degrees of freedom. Optical components were installed to imitate the MUVI instrument …

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How Quality Management Has Been Impacted In The Face Of Covid-19, Eldina Siljkovic Jan 2020

How Quality Management Has Been Impacted In The Face Of Covid-19, Eldina Siljkovic

Dissertations and Theses @ UNI

The Coronavirus pandemic has impacted many facets of the United States. This study focuses on its magnitude in comparison to prior pandemics such as Anthrax, SARS, and Ebola. In addition to this comparison its impact on Quality Management within the agricultural sector and food supply chain was also assessed. The results of these studies showcase that COVID-19 has grown exponentially in comparison to prior pandemics and will continue to do so as we enter the winter season. Agricultural equipment manufacturing companies saw a drastic decline in quarterly revenues within 2020 in comparison to 2019. Millions in net sales were lost …

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Adaptive Multi-Fidelity Modeling For Efficient Design Exploration Under Uncertainty, Atticus J. Beachy Jan 2020

Adaptive Multi-Fidelity Modeling For Efficient Design Exploration Under Uncertainty, Atticus J. Beachy

Browse all Theses and Dissertations

This thesis work introduces a novel multi-fidelity modeling framework, which is designed to address the practical challenges encountered in Aerospace vehicle design when 1) multiple low-fidelity models exist, 2) each low-fidelity model may only be correlated with the high-fidelity model in part of the design domain, and 3) models may contain noise or uncertainty. The proposed approach approximates a high-fidelity model by consolidating multiple low-fidelity models using the localized Galerkin formulation. Also, two adaptive sampling methods are developed to efficiently construct an accurate model. The first acquisition formulation, expected effectiveness, searches for the global optimum and is useful for modeling …

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Turbine Passage Vortex Response To Upstream Periodic Disturbances, Mitchell Lee Scott Jan 2020

Turbine Passage Vortex Response To Upstream Periodic Disturbances, Mitchell Lee Scott

Browse all Theses and Dissertations

Flow through the turbine section of gas turbine engines is inherently unsteady due to a variety of factors, such as the relative motion of rotors and stators. In low pressure turbines, periodic wake passing has been shown to impact boundary layer separation, blade surface pressure distribution, and loss generation. The effect of periodic disturbances on the endwall flow is less understood. Endwall flow in a low-pressure turbine occurs in the boundary layer region of the flow through the blade passage where the blade attaches to the hub in the turbine. The response of an endwall vortical structure, the passage vortex, …

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Thermal Modeling Of Coordinated Multi-Beam Additive Manufacturing, Rachel Elizabeth Evans Jan 2020

Thermal Modeling Of Coordinated Multi-Beam Additive Manufacturing, Rachel Elizabeth Evans

Browse all Theses and Dissertations

In additive manufacturing (AM), it is necessary to know the influence of processing parameters in order to have better control over the microstructure and mechanical performance of the part. Laser powder bed fusion (LPBF) is a metal AM process in which thin layers of powdered material are selectively melted to create a three-dimensional structure. This manufacturing process is beneficial for many reasons; however, it is limited by the thermal solidification conditions achievable in the available processing parameter ranges for single-beam processing methods. Therefore, this work investigates the effect of multiple, coordinated heat sources, which are used to strategically modify the …

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Defect Modeling And Vibration-Based Bending Fatigue Of Additively Manufactured Inconel 718, Wesley Earl Eldt Jan 2020

Defect Modeling And Vibration-Based Bending Fatigue Of Additively Manufactured Inconel 718, Wesley Earl Eldt

Browse all Theses and Dissertations

Additive manufacturing (AM) is convenient for building components with complex features. However, the long-term integrity of these components is uncertain, since AM parts have defects such as pores and rough surfaces. In this work, an analytical model was developed to determine the impact of defects, and a novel bending fatigue test was used to determine the fatigue life of channeled specimens. The analytical model, based off the theory of critical distances, investigates coupled pores and predicts their potential for fatigue failure. This resulted in a maximum allowable pore size and spacing recommendation for coupled defects. Additionally, specimens with through channels …

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Bibliometric Analysis Of Bearing Fault Detection Using Artificial Intelligence, Pooja Kamat, Rekha Sugandhi Dr. Jan 2020

Bibliometric Analysis Of Bearing Fault Detection Using Artificial Intelligence, Pooja Kamat, Rekha Sugandhi Dr.

Library Philosophy and Practice (e-journal)

The new industrial revolution called Industry 4.0 is proliferating at its peak. The time is no longer away when the human race is going to witness a huge paradigm shift. Intelligent machines empowered by Artificial Intelligence (AI)will take over the presence of human workers in the industrial manufacturing sector with the target of achieving 100% automation. With the emergence of cut-throat price competition in the product market, it has become equally important to manufacture goods at minimal costs and with the highest quality. Predicting the decrease in machinery efficiency at an earlier stage to accomplish this objective helps to reduce …

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Environmental Advantages In Additive Manufacturing, Analise Walter, Cheryl Marcham Jan 2020

Environmental Advantages In Additive Manufacturing, Analise Walter, Cheryl Marcham

Publications

Additive Manufacturing (AM) is a technology that uses a variety of methods to ultimately apply layers of material and create products (Ford & Despeisse, 2016; Ford, Mortara & Minshall, 2016). Although there has been an expansion in recent technology, AM has been used in manufacturing for a few decades (Ford, Mortara, et al., 2016). Since the late 1980s, AM has grown from simple product designs, with a focus on prototyping and customization, to modern times with billions of dollars in revenue and large-scale production of consumer and industrial products (Cotteleer, 2014). Forecasts showed a near $10 billion market by 2020, …

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Thermal Performance Of Sierpinski Carpet Fractal Fins At Various Angles Of Inclination In A Natural Convection Environment, Haidar Jamil Khalil Jan 2020

Thermal Performance Of Sierpinski Carpet Fractal Fins At Various Angles Of Inclination In A Natural Convection Environment, Haidar Jamil Khalil

Electronic Theses and Dissertations

As technology advances, higher performance cooling systems are desired to meet numerous thermal management challenges. Extended surfaces, also known as heat sinks or fins, are commonly used to passively dissipate unwanted heat from mechanical and electrical systems. Fractal fins in accordance with the first four iterations (including a base iteration) of the Sierpinski carpet, manufactured from AL-5052, were studied along seven different inclinations from 0° (orientated perpendicular to the direction of gravity) to 90° (orientated parallel to the direction of gravity), in iterations of 15°. The purpose of study was to investigate the thermal performance of the first four fractal …

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Detailed Energy Efficiency Strategies For Converting An Existing Office Building To Nzeb: A Case Study In The Pacific Northwest, Ali Alajmi, Abby Short, Janna Ferguson, Kalina K. Vander Poel, Corey T. Griffin Jan 2020

Detailed Energy Efficiency Strategies For Converting An Existing Office Building To Nzeb: A Case Study In The Pacific Northwest, Ali Alajmi, Abby Short, Janna Ferguson, Kalina K. Vander Poel, Corey T. Griffin

Mechanical and Materials Engineering Faculty Publications and Presentations

This paper is an attempt to identify a methodology for converting conventional energy consumption buildings to net-zero energy buildings (NZEB). The first step was rather different from the usual energy audit, which is to analyze a facility’s energy consumptions from both macro- and micro-scales. To implement such an approach, a governmental office building (Metro) in Portland, OR, was chosen as a case study. After a building model was validated against a real measurement, it was then used to evaluate different energy efficiency strategies (EESs) so as to reduce the energy consumption. The EESs showed a reduction in energy use intensity …

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A Dynamic Neural Network Designed Using Analytical Methods Produces Dynamic Control Properties Similar To An Analogous Classical Controller, Wade William Hilts, Nicholas Szczecinski, Roger Quinn, Alexander Hunt Jan 2020

A Dynamic Neural Network Designed Using Analytical Methods Produces Dynamic Control Properties Similar To An Analogous Classical Controller, Wade William Hilts, Nicholas Szczecinski, Roger Quinn, Alexander Hunt

Mechanical and Materials Engineering Faculty Publications and Presentations

Human balance is achieved using many concurrent control loops that combine to react to changes in environment, posture, center of mass and other factors affecting stability. Though numerous engineering models of human balance control have been tested, no methods for porting these models to a neural architecture have been established. It is our hypothesis that the analytical methods we have developed, combined with classical control techniques will provide a reasonable starting point for developing dynamic neural controllers that can reproduce classical control capabilities. In previous work, we tested this hypothesis and demonstrated that a biologically-constrained neural controller that replicates human …

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Utility-Scale Solar Pv Performance Enhancements Through System-Level Modifications, Andrew D. S. Glick, Naseem Ali, Juliaan Bossuyt, Marc Calaf, Raul Bayoan Cal Jan 2020

Utility-Scale Solar Pv Performance Enhancements Through System-Level Modifications, Andrew D. S. Glick, Naseem Ali, Juliaan Bossuyt, Marc Calaf, Raul Bayoan Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

Performance of solar PV diminishes with the increase in temperature of the solar modules. Therefore, to further facilitate the reduction in cost of photovoltaic energy, new approaches to limit module temperature increase in natural ambient conditions should be explored. Thus far only approaches based at the individual panel level have been investigated, while the more complex, systems approach remains unexplored. Here, we perform the first wind tunnel scaled solar farm experiments to investigate the potential for temperature reduction through system-level flow enhancement. The percentage of solar irradiance converted into electric power depends upon module efficiency, typically less than 20%. The …

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Openfoam Simulations Of Late Stage Container Draining In Microgravity, Joshua Thomas Mccraney, Mark M. Weislogel, Paul Steen Jan 2020

Openfoam Simulations Of Late Stage Container Draining In Microgravity, Joshua Thomas Mccraney, Mark M. Weislogel, Paul Steen

Mechanical and Materials Engineering Faculty Publications and Presentations

In the reduced acceleration environment aboard orbiting spacecraft, capillary forces are often exploited to access and control the location and stability of fuels, propellants, coolants, and biological liquids in containers (tanks) for life support. To access the ‘far reaches’ of such tanks, the passive capillary pumping mechanism of interior corner networks can be employed to achieve high levels of draining. With knowledge of maximal corner drain rates, gas ingestion can be avoided and accurate drain transients predicted. In this paper, we benchmark a numerical method for the symmetric draining of capillary liquids in simple interior corners. The free surface is …

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