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Portland State University

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Articles 121 - 150 of 331

Full-Text Articles in Mechanical Engineering

Technoeconomic Analysis Of Changing Pv Array Convective Cooling Through Changing Array Spacing, Matthew Prilliman, Sarah E. Smith, Brooke Stanislawski, Janine M.F. Keith, Timothy J. Silverman, Marc Calaf, Raul Bayoan Cal Sep 2022

Technoeconomic Analysis Of Changing Pv Array Convective Cooling Through Changing Array Spacing, Matthew Prilliman, Sarah E. Smith, Brooke Stanislawski, Janine M.F. Keith, Timothy J. Silverman, Marc Calaf, Raul Bayoan Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

Accuracy in photovoltaic (PV) module temperature modeling is crucial to achieving precision in energy performance yield calculations and subsequent economic evaluations of PV projects. While there have been numerous approaches to PV temperature modeling based on both the steady-state and transient thermal assumptions, there have been few attempts to account for changing convective cooling on PV module surfaces resulting from changes in the PV system layout. Changes in system row spacing, in particular, can have a meaningful impact on module electrical efficiency and subsequent economic performance, even when considering additional costs from the changes in row spacing. Using a heat …

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Identifying Population Hollowing Out Regions And Their Dynamic Characteristics Across Central China, Bin Guo, Yi Bian, Lin Pei, Xiaowei Zhu, Dingming Zhang, Wencai Zhang, Xianan Guo, Qiuji Chen Sep 2022

Identifying Population Hollowing Out Regions And Their Dynamic Characteristics Across Central China, Bin Guo, Yi Bian, Lin Pei, Xiaowei Zhu, Dingming Zhang, Wencai Zhang, Xianan Guo, Qiuji Chen

Mechanical and Materials Engineering Faculty Publications and Presentations

Continuous urbanization and industrialization lead to plenty of rural residents migrating to cities for a living, which seriously accelerated the population hollowing issues. This generated series of social issues, including residential estate idle and numerous vigorous laborers migrating from undeveloped rural areas to wealthy cities and towns. Quantitatively determining the population hollowing characteristic is the priority task of realizing rural revitalization. However, the traditional field investigation methods have obvious deficiencies in describing socio-economic phenomena, especially population hollowing, due to weak efficiency and low accuracy. Here, this paper conceives a novel scheme for representing population hollowing levels and exploring the spatiotemporal …

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A Lacunarity-Based Index For Spatial Heterogeneity, Ryan H. Scott, Hawwa Falih Kadum, G. Salmaso, Marc Calaf, Raul Bayoan Cal Aug 2022

A Lacunarity-Based Index For Spatial Heterogeneity, Ryan H. Scott, Hawwa Falih Kadum, G. Salmaso, Marc Calaf, Raul Bayoan Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

Characteri zing spatial heterogeneity is fundamental in numerous areas, yet defining spatial patterns often depends on qualitative assessments or a priori knowledge. Lacunarity analysis is a popular occupancy-based method for identi fy ing relevant length scales in spatially heterogeneous systems. From lacunarity, we identify the ex istence of a point which encapsulates the spatial heterogeneity of a given system. This value sati sfies the conditions for the lac unarity cutoff function and forms the bas is of a heterogeneity index. We evaluate the behavior of both parameters in mono fractal, clustered, and periodic systems. ln addition, we demonstrate the broad …

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Ti–6al–4v Alloy Deposition Characteristics At Electrode-Negative Polarity In The Cold Metal Transfer–Gas Metal Arc Process, Tae Hyun Lee, Dong Hyuck Kam, Je Hoon Oh, Cheolhee Kim Jul 2022

Ti–6al–4v Alloy Deposition Characteristics At Electrode-Negative Polarity In The Cold Metal Transfer–Gas Metal Arc Process, Tae Hyun Lee, Dong Hyuck Kam, Je Hoon Oh, Cheolhee Kim

Mechanical and Materials Engineering Faculty Publications and Presentations

Although wire arc additive manufacturing (WAAM) of Ti alloys using gas metal arc yields a high deposition rate, cathode spots exhibit unstable behavior. In this study, the cold-metal-transfer process and an electrode-negative (EN) polarity were used in the WAAM process of the Ti–6Al–4V alloy. High-speed imaging was performed to investigate the mechanisms to stabilize cathode plasma jets, arc plasma, and molten metal transfer in the EN polarity. Arc plasma and cathode jets had the same direction, and sound cathode jets were shrouded by arc plasma in the EN mode. The metal transfer was also stabilized by balanced plasma formation under …

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Thermophysical Properties Of Inorganic Phase-Change Materials Based On Mncl2·4h2o, Kyung-Eun Min, Jae-Won Jang, Jun-Ki Kim, Chien Wern, Sung Yi Jun 2022

Thermophysical Properties Of Inorganic Phase-Change Materials Based On Mncl2·4h2o, Kyung-Eun Min, Jae-Won Jang, Jun-Ki Kim, Chien Wern, Sung Yi

Mechanical and Materials Engineering Faculty Publications and Presentations

Manganese (II) chloride tetrahydrate, classified as an inorganic phase-change material (PCM), can be used as a thermal energy storage material, saving and releasing thermal energy during its phase transitions. In this study, thermophysical properties, such as phase change temperatures, latent heat, and thermal conductivities, of four types of MnCl2·4H2O PCMs were investigated under single and dual phases (liquid-, solid-, and dual-phase PCMs) using differential scanning calorimetry (DSC) and a heat flow meter. PCMs with a liquid or dual phases exhibited superheating issues, and their melting temperatures were 7 to 10 °C higher than the reference melting …

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Effectiveness Of Air Pollution Mitigation Systems: Transport, Transformation, And Control Of Ozone In The Indoor Environment, Pradeep Ramasubramanian Jun 2022

Effectiveness Of Air Pollution Mitigation Systems: Transport, Transformation, And Control Of Ozone In The Indoor Environment, Pradeep Ramasubramanian

Dissertations and Theses

Buildings are critical environments governing our collective exposure to air pollution and energy consumption. While there exist concerns regarding increases in building energy consumption due to indoor air interventions, improvements to the quality of air indoors can improve health, comfort, and productivity. Air cleaning technologies that can improve indoor air quality with minimal energy consumption have become ever more important. These technologies are utilized at various scales; from passive removal of pollutants in the air entering the indoor environment to active cleaning of air within the breathing zone. To better understand the effectiveness of active and passive ozone mitigation technologies …

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Wake Bifurcations Behind Two Circular Disks In Tandem Arrangement, Jianzhi Yang, Xiaowei Wu, Minghou Liu, Changjian Wang, Yuxin Wu, Zhihe Shen Jun 2022

Wake Bifurcations Behind Two Circular Disks In Tandem Arrangement, Jianzhi Yang, Xiaowei Wu, Minghou Liu, Changjian Wang, Yuxin Wu, Zhihe Shen

Mechanical and Materials Engineering Faculty Publications and Presentations

The wake bifurcations behind two circular disks in tandem arrangement are investigated through numerical simulations. The separation distance between the disks, S/d, is chosen at 1, 2, 4, and 6, and the Reynolds number, Re, lies in the range of 100 Re 500. The wake dynamics are examined in terms of the flow structures as well as drag and lift coefficient characteristics. Seven main wake regimes are observed in the considered (Re, S/d) space: steady state (SS), Zig-zig (Zz) mode, standing wave mode, periodic state with reflectional symmetry breaking (RSB), periodic state with double-helical (DH) structures shedding, periodic state with …

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How Advances In Low-G Plumbing Enable Space Exploration, Mark M. Weislogel, John Graft, Andrew P. Wollman, Karl Cardin, Logan Torres, J. E. Goodman, J. C. Buchli Jun 2022

How Advances In Low-G Plumbing Enable Space Exploration, Mark M. Weislogel, John Graft, Andrew P. Wollman, Karl Cardin, Logan Torres, J. E. Goodman, J. C. Buchli

Mechanical and Materials Engineering Faculty Publications and Presentations

In many ways, plumbing is essential to life support. In fact, the advance of humankind on Earth is directly linked to the advance of clean, healthy, reliable plumbing solutions. Shouldn’t this also be true for the advancement of humankind in space? Unfortunately, the reliability of even the simplest plumbing element aboard spacecraft is rarely that of its terrestrial counterpart. This state of affairs is due entirely to the near-weightless “low-g” state of orbiting and coast spacecraft. But the combined passive capillary effects of surface tension, wetting, and system geometry in space can be exploited to replace the passive role of …

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Characteristics Of The Wake Of An Inclined Prolate Spheroid In Uniform Shear Flow, Zhe Wang, Jianzhi Yang, Helge I. Andersson, Xiaowei Wu, Yuxin Wu, Liping Wang, Minghou Liu May 2022

Characteristics Of The Wake Of An Inclined Prolate Spheroid In Uniform Shear Flow, Zhe Wang, Jianzhi Yang, Helge I. Andersson, Xiaowei Wu, Yuxin Wu, Liping Wang, Minghou Liu

Mechanical and Materials Engineering Faculty Publications and Presentations

Flow around an inclined 5:2 prolate spheroid with the incidence angle α = 45° is numerically investigated in a uniform shear flow. The Reynolds number based on the inflow center velocity Uc and the volume-equivalent sphere diameter De of the spheroid are considered at Re = 480, 600, 700, and 750. The non-dimensional shear rate K is ranged from 0 to 0.1. Five qualitatively different wake modes are observed, including a new mode characterized by multi-periodic shedding of hairpin vortices with regular rotation of the separation region. In general, the wake transition is suppressed with increasing shear rate. …

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Building A Turbulent Jet: Measuring/Modeling Lagrangian Dispersion, Particle Trajectory Dynamics And Intermittency, Bianca Fontanin Viggiano Apr 2022

Building A Turbulent Jet: Measuring/Modeling Lagrangian Dispersion, Particle Trajectory Dynamics And Intermittency, Bianca Fontanin Viggiano

Dissertations and Theses

The mechanics of how particles diffuse, interact, eject, etc. within a fluid is applicable to numerous industrial and environmental applications. Unwanted products of combustion, dust contamination of solar panels, pathogen transport during a cough and ejections of particles during volcanic eruptions, are a few examples of flows in which increased knowledge of particle dynamics could result in substantial reduction of negative environmental and economic impacts. To better understand the tendencies of particles within shearing flows (such as jets), an extensive experimental campaign was conducted. Measurements of a turbulent round water jet were performed within an icosahedral tank. Particle tracking velocimetry …

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Measuring Volatile Emissions From Moss Gametophytes: A Review Of Methodologies And New Applications, Danlyn L. Brennan, Leslie M. Kollar, Scott Kiel, Timea Deakova, Aurélie Laguerre, Stuart F. Mcdaniel, Sarah Eppley, Elliott T. Gall, Todd Rosenstiel Apr 2022

Measuring Volatile Emissions From Moss Gametophytes: A Review Of Methodologies And New Applications, Danlyn L. Brennan, Leslie M. Kollar, Scott Kiel, Timea Deakova, Aurélie Laguerre, Stuart F. Mcdaniel, Sarah Eppley, Elliott T. Gall, Todd Rosenstiel

Center for Life in Extreme Environments Publications

Mosses inhabit nearly all terrestrial ecosystems and engage in important interactions with nitrogen-fixing microbes, sperm-dispersing arthropods, and other plants. It is hypothesized that these interactions could be mediated by biogenic volatile organic compounds (BVOCs). Moss BVOCs may play fundamental roles in influencing local ecologies, such as biosphere–atmosphere–hydrosphere communications, physiological and evolutionary dynamics, plant–microbe interactions, and gametophyte stress physiology. Further progress in quantifying the composition, magnitude, and variability of moss BVOC emissions, and their response to environmental drivers and metabolic requirements, is limited by methodological and analytical challenges. We review several sampling techniques with various analytical approaches and describe best practices …

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Effects Of Electrode Negative Pulsing Ratio In Direct Energy Deposition Via Variable-Polarity Cold Metal Transfer Process On The Deposition Behavior And Microstructural Characteristics, Tae Hyun Lee, Cheolhee Kim, Minjung Kang Apr 2022

Effects Of Electrode Negative Pulsing Ratio In Direct Energy Deposition Via Variable-Polarity Cold Metal Transfer Process On The Deposition Behavior And Microstructural Characteristics, Tae Hyun Lee, Cheolhee Kim, Minjung Kang

Mechanical and Materials Engineering Faculty Publications and Presentations

Interest in research on the application of variable-polarity cold metal transfer mode in wire-based direct energy deposition has been growing; particularly popular are investigations into the respective influences of polarity, amplitude of the arc current, and polarity variation sequence on the quality of the final product manufactured via additive manufacturing. The application of the electrode-negative phase is more capable of yielding relatively large droplets and increasing the weight of the deposited material. However, the proportions of the electrode positive phase are typically larger than those of the electrode-negative phase because it maintains arc stability and droplet transfer. This discrepancy has …

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Secondary Motions Above A Staggered Multi-Scale Rough Wall, Bianca Viggiano, Juliaan Bossuyt, N. Ali, Johan Meyers, Raul Bayoan Cal Apr 2022

Secondary Motions Above A Staggered Multi-Scale Rough Wall, Bianca Viggiano, Juliaan Bossuyt, N. Ali, Johan Meyers, Raul Bayoan Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

Wind tunnel experiments were performed to investigate turbulent flow over an array of heterogeneous roughness elements using stereoscopic particle image velocimetry. Nine streamwise planes, covering one periodic cell of a multi-scale roughness element that is arranged in a staggered pattern, are combined to quantify mean flow features and Reynolds stresses. Dispersive stresses, arising from spatial variations in the temporally averaged mean velocity, are also presented. The results highlight that the roughness elements create a large deficit pathway along the surfaces. Outer scaling of the time-averaged streamwise velocity presents features which are nearly independent of the roughness element type, with parameters …

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Quantification Of Reynolds Shear Stress Wave-Phase Dependence In Fixed-Bottom Offshore Wind Turbine Via Quadrant Analysis, Cerrina Mouchref Mar 2022

Quantification Of Reynolds Shear Stress Wave-Phase Dependence In Fixed-Bottom Offshore Wind Turbine Via Quadrant Analysis, Cerrina Mouchref

University Honors Theses

As the need for a reliable renewable energy supply is increasing, many have looked to offshore wind because they hold more potential for power production than onshore wind. Interests in expanding offshore wind energy has brought along many challenges when it comes to understanding the complex dynamics experienced offshore, including the relationship between the wind-turbine generated wakes and ocean waves. This experimental study characterizes the relationship between Reynolds shear stress and the phase of surface waves above the air-sea interface in the wind-turbine wake region. The experimental setup combines a wave tank, wind tunnel, and a fixed-bottom wind turbine. Particle …

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Per-Person And Whole-Building Voc Emission Factors In An Occupied School With Gas-Phase Air Cleaning., Brett W. Stinson, Aurélie Laguerre, Elliott T. Gall Feb 2022

Per-Person And Whole-Building Voc Emission Factors In An Occupied School With Gas-Phase Air Cleaning., Brett W. Stinson, Aurélie Laguerre, Elliott T. Gall

Mechanical and Materials Engineering Faculty Publications and Presentations

Using real-time measurements of CO and volatile organic compounds (VOCs) in the air handler of an occupied middle school, we quantified source strengths for 249 VOCs and apportioned the source to the building, occupants and their activities, outdoor air, or recirculation air. For VOCs quantified in this study, there is a source to the outdoors of 8.6 ± 1.8 g/h in building exhaust air, of which 5.9 ± 1.7 g/h can be attributed to indoor sources (the building and occupants and their activities). The corresponding whole-building area emission factor from indoor sources is 1020 ± 300 μg/(m h), including reactive …

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Novel Fabrication Of Silver-Coated Copper Nanowires With Organic Compound Solution, Suhyun Lee, Chien Wern, Sung Yi Feb 2022

Novel Fabrication Of Silver-Coated Copper Nanowires With Organic Compound Solution, Suhyun Lee, Chien Wern, Sung Yi

Mechanical and Materials Engineering Faculty Publications and Presentations

Copper nanowires and Cu-Ag nanowires have various potential applications, such as transparent conductive film, flexible electronics, and conductive filler. In this study, we developed a new green fabrication method for silver-coated copper nanowires using methylsulfonylmethane (DMSO2), which is an environmentally friendly chemical at the food-grade level, to replace toxic chemicals, including ammonia, in the silver coating process. Copper nanowires were synthesized under various reaction temperatures and concentrations of hydrazine (N2H4), ethylenediamine (EDA), sodium hydroxide (NaOH), and copper precursor. The reaction temperature higher than 70 C caused the oxidation of copper products and evaporation of the sample solution. The optimal conditions …

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Analyzing Modeled Torque Profiles To Understand Scale-Dependent Active Muscle Responses In The Hip Joint, Fletcher Young, Hillel J. Chiel, Matthew Tresch, Charles Heckman, Alexander J. Hunt, Roger Quinn Jan 2022

Analyzing Modeled Torque Profiles To Understand Scale-Dependent Active Muscle Responses In The Hip Joint, Fletcher Young, Hillel J. Chiel, Matthew Tresch, Charles Heckman, Alexander J. Hunt, Roger Quinn

Mechanical and Materials Engineering Faculty Publications and Presentations

Animal locomotion is influenced by a combination of constituent joint torques (e.g., due to limb inertia and passive viscoelasticity), which determine the necessary muscular response to move the limb. Across animal size-scales, the relative contributions of these constituent joint torques affect the muscular response in different ways. We used a multi-muscle biomechanical model to analyze how passive torque components change due to an animal’s size-scale during locomotion. By changing the size-scale of the model, we characterized emergent muscular responses at the hip as a result of the changing constituent torque profile. Specifically, we found that activation phases between extensor and …

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Entrainment, Diffusion And Effective Compressibility In A Self-Similar Turbulent Jet, Thomas Basset, Bianca Viggiano, Thomas Barois, Mathieu Gibert, Nicolas Mordant, Raúl Bayoán Cal, Romain Volk, Mickael Bourgoin Jan 2022

Entrainment, Diffusion And Effective Compressibility In A Self-Similar Turbulent Jet, Thomas Basset, Bianca Viggiano, Thomas Barois, Mathieu Gibert, Nicolas Mordant, Raúl Bayoán Cal, Romain Volk, Mickael Bourgoin

Mechanical and Materials Engineering Faculty Publications and Presentations

An experimental Lagrangian study based on particle tracking velocimetry has been completed in an incompressible turbulent round water jet freely spreading into water. The jet is seeded with tracers only through the nozzle: inhomogeneous seeding called nozzle seeding. The Lagrangian flow tagged by these tracers therefore does not contain any contribution from particles entrained into the jet from the quiescent surrounding fluid. The mean velocity field of the nozzle seeded flow, ⟨Uφ⟩, is found to be essentially indistinguishable from the global mean velocity field of the jet, ⟨U⟩, for the axial velocity while significant deviations are found for the radial …

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The Evaluation Of Performance Of Spindle Connector And Its Finite Element Analysis, Suhyun Lee Dec 2021

The Evaluation Of Performance Of Spindle Connector And Its Finite Element Analysis, Suhyun Lee

Dissertations and Theses

The rapid development of machining technology and reliable high-speed machining systems has led to a fast operation of machines. However, machining machines cannot still meet modern requirements in terms of the quality of parts, the machine components, and the life of the tools. The major components of the machining system are machine tools, the spindle interfaces (the contact between the spindle and the tool holder), and tools. The choice of the spindle connector is the main decision, as this defines the limitation of the metal cutting efficiency and considerably influences the deformation of the machine tool. Therefore, it is very …

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Microstructure And Mechanical Properties Of Cast And Hot-Rolled Medium-Carbon Steels Under Isothermal Heat-Treatment Conditions, Byungsue Shin, Kwangyuk Kim, Sung Yi, Sanggyu Choi, Soongkeun Hyun Dec 2021

Microstructure And Mechanical Properties Of Cast And Hot-Rolled Medium-Carbon Steels Under Isothermal Heat-Treatment Conditions, Byungsue Shin, Kwangyuk Kim, Sung Yi, Sanggyu Choi, Soongkeun Hyun

Mechanical and Materials Engineering Faculty Publications and Presentations

In this study, the changes in the microstructure and mechanical properties during isothermal heat treatment of cast steel before and after hot deformation were investigated using medium carbon steel with low alloy content. The microstructural characteristics of the cast and hot-rolled medium-carbon steel under isothermal heat-treatment conditions were examined using optical microscopy and scanning electron microscopy in conjunction with electron backscatter diffraction. The variation in the mechanical properties was evaluated using Rockwell hardness and tensile tests. After maintaining an austenitizing condition at 1200 ◦C for 30 min, an isothermal heat treatment was performed in the range 350–500 ◦C, followed by …

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Characterization Of Coupling Between Inertial Particles And Turbulent Wakes From Porous Disk Generators, Kristin N. Travis, Sarah E. Smith, Laure Vignal, Henda Djeridi, Mickael Bourgoin, Raul Bayoan Cal, Martin Obligado Dec 2021

Characterization Of Coupling Between Inertial Particles And Turbulent Wakes From Porous Disk Generators, Kristin N. Travis, Sarah E. Smith, Laure Vignal, Henda Djeridi, Mickael Bourgoin, Raul Bayoan Cal, Martin Obligado

Mechanical and Materials Engineering Faculty Publications and Presentations

This study presents the findings of a wind tunnel experiment investigating the behaviour of micrometric inertial particles with Stokes numbers around unity in the turbulent wake of a stationary porous disk. Various concentrations Φv ∈ ([6 − 19] × 10−6) of poly-disperse water droplets (average diameter 40–50μm) are compared with sub-inertial tracer particles. Hot-wire anemometry, phase Doppler interferometry and particle image velocimetry were implemented in the near- and far-wake regions to study the complex dynamics of such particles. Quadrant analysis is used to explore the shear effects of the particle wake interaction. Turbulence statistics and particle size distributions reveal distinct …

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The Ejection Of Large Non-Oscillating Droplets From A Hydrophobic Wedge In Microgravity, Logan Torres, Mark M. Weislogel Dec 2021

The Ejection Of Large Non-Oscillating Droplets From A Hydrophobic Wedge In Microgravity, Logan Torres, Mark M. Weislogel

Mechanical and Materials Engineering Faculty Publications and Presentations

When confined within containers or conduits, drops and bubbles migrate to regions of minimum energy by the combined effects of surface tension, surface wetting, system geometry, and initial conditions. Such capillary phenomena are exploited for passive phase separation operations in micro-fluidic devices on earth and macro-fluidic devices aboard spacecraft. Our study focuses on the migration and ejection of large inertial-capillary drops confined between tilted planar hydrophobic substrates (a.k.a., wedges). In our experiments, the brief nearly weightless environment of a 2.1 s drop tower allows for the study of such capillary dominated behavior for up to 10 mL water drops with …

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The Effect Of Viscosity On The Puddle Dynamics In Low Gravity Environment, Taif Hamed Saleh Al Juboori Nov 2021

The Effect Of Viscosity On The Puddle Dynamics In Low Gravity Environment, Taif Hamed Saleh Al Juboori

Dissertations and Theses

Enormous liquid puddles are observed to jump spontaneously from non-wetting substrates when exposed to the nearly step-reduction in body force common to drop tower test facilities. The phenomenon is similar to the second half of terrestrial drop bounce experiments except that (1) the initial static equilibrium configuration satisfies the static contact angle condition, (2) the initial height of the puddle is limited to the capillary height, and (3), for drop tower test durations on the order of seconds, puddle volumes can be over 104 times larger in mass (volume). The passive puddle jump mechanism provides a no-moving-parts deployment method …

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The Draining Of Capillary Liquids From Containers With Interior Corners Aboard The Iss, Joshua Thomas Mccraney, Mark M. Weislogel, Paul Steen Nov 2021

The Draining Of Capillary Liquids From Containers With Interior Corners Aboard The Iss, Joshua Thomas Mccraney, Mark M. Weislogel, Paul Steen

Mechanical and Materials Engineering Faculty Publications and Presentations

In this work, we analyze liquid drains from containers in effective zero-g conditions aboard the International Space Station (ISS). The efficient draining of capillary fluids from conduits, containers, and media is critical in particular to high-value liquid samples such as minuscule biofluidics processing on earth and enormous cryogenic fuels management aboard spacecraft. The amount and rate of liquid drained can be of key concern. In the absence of strong gravitational effects, system geometry, and liquid wetting dominate capillary fluidic behavior. During the years 2010–2015, NASA conducted a series of handheld experiments aboard the ISS to observe “large” length scale capillary …

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High-Entropy Alloys Properties Prediction Model By Using Artificial Neural Network Algorithm, Sanggyu Choi, Sung Yi, Junghan Kim, Byungsue Shin, Soongkeun Hyun Oct 2021

High-Entropy Alloys Properties Prediction Model By Using Artificial Neural Network Algorithm, Sanggyu Choi, Sung Yi, Junghan Kim, Byungsue Shin, Soongkeun Hyun

Mechanical and Materials Engineering Faculty Publications and Presentations

A new approach method has been studied for the efficient and accurate prediction of high-entropy alloys (HEAs) properties. The artificial neural network (ANN) algorithm was employed to predict the mechanical properties such as yield strength, microstructure, and elongation of the alloy by training from the mole fraction and post-process information that has an influence on the mechanical properties. The mean error rate of prediction for the yield strength was 19.6%. Microstructure predictions were consistent for all test data. On the other hand, the ANN model trained only with mole fraction data had a yield strength prediction error of 33.9%. Omission …

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Building A Biomechanical Model Of A Rat Forelimb, Joshua Nathaniel Eric Mak Sep 2021

Building A Biomechanical Model Of A Rat Forelimb, Joshua Nathaniel Eric Mak

Dissertations and Theses

This paper presents a biomechanical model of the rat forelimb to test theories of determining viscoelastic muscle parameters. Several biomechanical models of rat hindlimbs have been developed and have explored the effects of multi-muscle control during locomotion. The forelimb model uses two ball-and-socket joints to model clavicle and scapula movement. A third ball-and-socket joint is used at the shoulder and two hinge joints are used at the elbow and wrist. Scapula motion is further constrained by muscle and spring elements. Each forelimb has 11 degrees of freedom, and 23 Hill-type muscles. The model has been created in Animatlab, which includes …

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Deep Learning-Based Penetration Depth Prediction In Al/Cu Laser Welding Using Spectrometer Signal And Ccd Image, Sanghoon Kang, Minjung Kang, Yong Hoon Jang, Cheolhee Kim Sep 2021

Deep Learning-Based Penetration Depth Prediction In Al/Cu Laser Welding Using Spectrometer Signal And Ccd Image, Sanghoon Kang, Minjung Kang, Yong Hoon Jang, Cheolhee Kim

Mechanical and Materials Engineering Faculty Publications and Presentations

In the laser welding of thin Al/Cu sheets, proper penetration depth and wide interface bead width ensure stable joint strength and low electrical conductance. In this study, we proposed deep learning models to predict the penetration depth. The inputs for the prediction models were 500 Hz-sampled low-cost charge-coupled device (CCD) camera images and 100 Hz-sampled spectral signals. The output was the penetration depth estimated from the keyhole depth measured coaxially using optical coherence tomography. A unisensor model using a CCD image and a multisensor model using a CCD image and the spectrometer signal were proposed in this study. The input …

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Fixed Bottom Wind Turbine Wave-Wake Interaction, Ondrej Fercak Jul 2021

Fixed Bottom Wind Turbine Wave-Wake Interaction, Ondrej Fercak

Dissertations and Theses

The interest and benefits of offshore wind energy has also brought along legitimate design challenges for engineers. Most notably, the complex interaction between wind and turbine is further complicated by the addition of dynamic ocean waves. This dynamic coupling between wind, wave, and turbine is not fully understood. Even small improvements in wind turbine performance are welcome, so characterizing a fundamental dynamic in offshore energy is necessary to optimize design. Experimentation and simulation have been used to characterize inflow and turbine wakes and separately, wind-wave interactions. But only simulations have just begun to look at the wind, wave, and turbine …

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Assessment Of Heat-Affected Zone Softening Of Hot-Press-Formed Steel Over 2.0 Gpa Tensile Strength With Bead-On-Plate Laser Welding, Kwangsoo Kim, Namhyun Kang, Minjung Kang, Cheolhee Kim Jul 2021

Assessment Of Heat-Affected Zone Softening Of Hot-Press-Formed Steel Over 2.0 Gpa Tensile Strength With Bead-On-Plate Laser Welding, Kwangsoo Kim, Namhyun Kang, Minjung Kang, Cheolhee Kim

Mechanical and Materials Engineering Faculty Publications and Presentations

High-strength hot-press-formed (HPF) steels with a fully martensitic microstructure are being widely used in the fabrication of automotive body structure, and 2.0 GPa-strength HPF steel has recently been commercially launched. However, heat-affected zone (HAZ) softening is unavoidable in welding martensitic steel. In this study, the HAZ softening characteristic of 2.0 GPa HPF steel was investigated by applying a high-brightness laser welding process, wherein the heat input was controlled by varying the welding speed. Microstructural evaluation and hardness test results showed that the base metal with a fully martensitic microstructure was changed to the same type of fully martensitic microstructure in …

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Optimization Of 3d Printed Mold Performance For Injection Molding Via Hollow Infill Patterns, Alan Fong Jul 2021

Optimization Of 3d Printed Mold Performance For Injection Molding Via Hollow Infill Patterns, Alan Fong

University Honors Theses

The applicability of hollow infill patterns has been explored for its applications in making 3D printed polymer-based injection molds in the additive manufacturing industry. Hollow infill patterns offer a significant reduction in material costs as well as the opportunity for reducing the cooling times via pumping a coolant fluid through the hollow cavity in a similar fashion to traditional conformal cooling channels. A 3D Jacks Support Hollow mold model was determined to be the best performing design. FEA analysis was conducted to determine the maximum reduction in internal volume (percentage of material saved) that could be achieved without exceeding the …

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