Engineering Commons^™

A Hydraulic Actuated Thermal Management System For Large Displacement Engine Cooling Systems, Peyton Frick

All Theses

The performance of automotive cooling systems can be improved by replacing the traditional mechanically driven radiator fan and water pump assemblies with computer controlled components. The introduction of electric servo-motors to drive the cooling components can improve temperature tracking, which should increase fuel efficiency and decrease tailpipe emissions. However, the power requirement for these electric motors increases with greater cooling demands if the radiator surface area remains constrained. For heavy-duty applications, where engines are subjected to significant cooling loads, electric motors may become impractical due to their increased size and power requirements; in these situations, hydraulic-based components are advantageous due …

Comparison Of Effectiveness Of Roadway Design Treatments For Transitioning From Rural Areas To Urban Areas Using A Driving Simulator, Candice Hein

All Theses

Traffic fatalities are a leading cause of death in the United States. Rural roads are especially hazardous as they account for 60 percent of all traffic fatalities in the United States. Three main reasons for the rural road problems are high speeds, low volumes, and reduced driver awareness. This is particularly problematic where these roads navigate through communities requiring reduced speeds. Drivers who aren't alert and are driving too fast often miss the reduced speed warning signs and often don't slow until after they have entered the community. Therefore, engineers must do something to the design of the roadway environment …

Registration Using Graphics Processor Unit, Koushik Aravalli

All Theses

Data point set registration is an important operation in coordinate metrology. Registration is the operation by which sampled point clouds are aligned with a CAD model by a 4X4 homogeneous transformation (e.g., rotation and translation). This alignment permits validation of the produced artifact's geometry. State-of-the-art metrology systems are now capable of generating thousands, if not millions, of data points during an inspection operation, resulting in increased computational power to fully utilize these larger data sets. The registration process is an iterative nonlinear optimization operation having an execution time directly related to the number of points processed and CAD model complexity. …

Simulation Of A Backrest Moment Test For An Automotive Front Seat Using Nonlinear Contact Finite Element Analysis , Abhinand Chelikani

All Theses

Computer aided engineering and finite element simulation are essential in order to predict accurately the safety performance of automotive structures in an event of crash. In this work, finite element simulation is used to evaluate the strength and deflection characteristics of a reference automotive front seat in an event of vehicle rear impact. Understanding the strength-deflection characteristics of front automotive seats during vehicle rear impact is important to ensure the safety function of the seat. The safety function is measured based on a moment test in accordance with government (ECE R17) regulations. Accurate finite element modeling of a reference seat …

Estimating Business And Residential Water Supply Interruption Losses From Catastrophic Events, Nicholas Brozovic, David L. Sunding, David Zilberman

Daugherty Water for Food Global Institute: Faculty Publications

Following man-made or natural catastrophes, widespread and long-lasting disruption of lifelines can lead to economic impacts for both business and residential lifeline users. As a result, the total economic losses caused by infrastructure damage may be much higher than the value of damage to infrastructure itself. In this paper, we consider the estimation of economic impacts on businesses and residential consumers resulting from water supply disruption. The methodology we present for estimating business interruption losses assumes that marginal losses are increasing in the severity of disruption and that there may be a critical water availability cutoff below which business activity …

Analysis Of Thermal Effects In Infrared And Interference Microscopy: N-Butane-5a And Methanol-Ferrierite Systems, Lars Heinke, Christian Chmelik, Pavel Kortunov, Dhananjai B. Shah, S. Brandani, Douglas M. Ruthven, Jörg Kärger

Chemical & Biomedical Engineering Faculty Publications

Recently, infrared and interference microscopy methods have been increasingly applied to measure internal concentration gradients and hence the uptake of different adsorbates in zeolite crystals. In contrast to conventional macroscopic batch uptake techniques, these microscopic/mesoscopic methods measure changes associated with single zeolite crystals. The analysis of data from these measurements to determine micropore diffusivities has been performed on the basis of the assumption that isothermal conditions prevail during both the adsorption and desorption experiments. This assumption is critically examined in this paper for the case of methanol diffusion in ferrierite crystals during adsorption and desorption to vacuum. It is shown …

Size Effect In Polymer Nanofibers Under Tension, Xiangfa Wu, Yuris A. Dzenis

Nebraska Center for Materials and Nanoscience: Faculty Publications

This article studies the size effect on the elastic behavior of solid and hollow polymer nanofibers (e.g., electrospun nanofibers) subjected to uniaxial tension. A one-dimensional nonlinear elastic tension model is proposed that takes into account the coupling effect of fiber elastic deformation and surface tension. The fiber axial force-displacement and stress-strain relations are obtained in explicit forms. It is shown that, at nanoscale, fiber radius has appreciable effect on the elastic response of polymer nanofibers. With consideration of the fiber radial effect, it is shown that the actual contribution of surface energy of the solid polymer fibers to the axial …

An Overview Of Snow Photochemistry: Evidence, Mechanisms And Impacts, A. M. Grannas, A. E. Jones, J. Dibb, M. Ammann, C. Anastasio, H. J. Beine, M. Bergin, J. Bottenheim, C. S. Boxe, G. Carver, G. Chen, J. H. Crawford, F. Dominé, R. E. Honrath, Et. Al.

Michigan Tech Publications, Part 1

It has been shown that sunlit snow and ice plays an important role in processing atmospheric species. Photochemical production of a variety of chemicals has recently been reported to occur in snow/ice and the release of these photochemically generated species may significantly impact the chemistry of the overlying atmosphere. Nitrogen oxide and oxidant precursor fluxes have been measured in a number of snow covered environments, where in some cases the emissions significantly impact the overlying boundary layer. For example, photochemical ozone production (such as that occurring in polluted mid-latitudes) of 3-4 ppbv/day has been observed at South Pole, due to …

A System Approach To Integrated Power Amplifier Analysis And Design, Vladimir I. Prodanov, Mihai Banu

Electrical Engineering

Numerous power amplifier circuits are described in the literature, which seem to follow many distinct design approaches. While circuit implementations may be quite different indeed, the underlining system-level signaling inside these circuits follows similar conditions dictated by the common design objective for high efficiency. This paper presents a general theory for analyzing and designing power amplifiers, providing an insight on the fundamental factors limiting the performance, irrespective of the implementation circuits or technology.

Spatial Confinement Effects In Laser-Induced Breakdown Spectroscopy, X. K. Shen, Jian Sun, Hao Ling, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

The spatial confinement effects in laser-induced breakdown of aluminum (A1) targets in air have been investigated both by optical emission spectroscopy and fast photography. A KrF excimer laser was used to produce plasmas from Al targets in air. Al atomic emission lines show an obvious enhancement in the emission intensity when a pair of Al-plate walls were placed to spatially confine the plasma plumes. Images of the Al plasma plumes showed that the plasma plumes evolved into a torus shape and were compressed in the Al walls. The mechanism for the confinement effects was discussed using shock wave theory.

Distributed Energy Resources: Issues And Challenges, Badrul H. Chowdhury, Chung-Li Tseng

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

Novel Method For Mechanical Characterization Of Polymeric Nanofibers, Mohammad Naraghi, Loannis Chasiotis, Harold Kahn, Yongkui Wen, Yuris A. Dzenis

Nebraska Center for Materials and Nanoscience: Faculty Publications

A novel method to perform nanoscale mechanical characterization of highly deformable nanofibers has been developed. A microelectromechanical system (MEMS) test platform with an on-chip leaf-spring load cell that was tuned with the aid of a focused ion beam was built for fiber gripping and force measurement and it was actuated with an external piezoelectric transducer. Submicron scale tensile tests were performed in ambient conditions under an optical microscope. Engineering stresses and strains were obtained directly from images of the MEMS platform, by extracting the relative rigid body displacements of the device components by digital image correlation. The accuracy in determining …

Wind Effects On Monosloped And Sawtooth Roofs, Bo Cui

All Dissertations

Wind is one of the significant forces of nature that must be considered in the design of buildings. The actual behavior of wind is influenced not only by the surface (or boundary-layer) conditions, but also by the geometry of the building. All sorts of turbulent effects occur, especially at building corners, edges, roof eaves. Some of these effects are accounted for by the wind pressure coefficient. Wind pressure coefficients used in practice have usually been obtained from experimentally by testing models of different type of structures in wind tunnels.
In this study, a series of wind tunnel tests with scale …

Effects Of Aggregates On Properties And Performance Of Mastics And Superpave Hot Mix Asphalt Mixtures, Francisco Aragão

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Superpave, a set of advancements in testing devices and specifications for asphalt binders and mixtures, was limited to address the effects of aggregates. Because aggregates represent around 95% in mass of the asphalt mixtures, it is important to understand how these materials affect properties and performance of such mixtures. This research focus on how different types and contents of aggregates affect properties of mastics and asphalt mixtures, and their performance considering the viscoelastic nature of the asphalt material.

Five different types of aggregates and hydrated lime were used for sample fabrication together with two different binders. Several different tests were …

Terahertz Scattering From Granular Material, Lisa M. Zurk, Brian Orlowski, Dale P. Winebrenner, Eric I. Thorsos, Megan R. Leahy-Hoppa, L. Michael Hayden

Electrical and Computer Engineering Faculty Publications and Presentations

Terahertz (THz) imaging is emerging as a potentially powerful method of detecting explosive devices, even in the presence of occluding materials. However, the characteristic spectral signatures of pure explosive materials may be altered or obscured by electromagnetic scattering caused by their granular nature. This paper presents THz transmission measurements of granular systems representative of explosives and presents results from dense media theory that accurately explain the observed scattering response.

Understanding And Optimizing Surfaces And Interfaces In Energy Conversion Devices, Clemens Heske

UNLV Renewable Energy Symposium

This inaugural event is dedicated to showcasing the renewable/sustainable energy projects of UNLV faculty, staff, students, and collaborators, as well as other external projects underway statewide and nationally. The development and utilization of new technologies to protect the environment, achieve energy independence, and strengthen the economy will be explored. Speakers and poster-session presenters will provide further insight to many ongoing projects and innovative research ideas.

Organized by UNLV’s Office of Strategic Energy Programs, the event offers participants the opportunity to learn about energy projects and will encourage networking and collaboration. This symposium is intended for researchers, educators, students, policy makers, …

Ceas E-News 08.16.2007, College Of Engineering And Applied Sciences

College of Engineering and Applied Sciences News

CEAS hydraulic bike wins national Chainless Challenge

Two-Dimensional Modeling Of Ap/Htpb Utilizing A Vorticity Formulation And One-Dimensional Modeling Of Ap And Adn, Matthew L. Gross

Theses and Dissertations

This document details original numerical studies performed by the author pertaining to the propellant oxidizer, ammonium perchlorate (AP). Detailed kinetic mechanisms have been utilized to model the combustion of the monopropellants AP and ADN, and a two-dimensional diffusion flame model has been developed to examine the flame structure above an AP/HTPB composite propellant. This work was part of an ongoing effort to develop theoretically based, a priori combustion models. The improved numerical model for AP combustion utilizes a “universal” gas-phase kinetic mechanism previously applied to combustion models of HMX, RDX, GAP, GAP/RDX, GAP/HMX, NG, BTTN, TMETN, GAP/BTTN, and GAP/RDX/BTTN. The …

Particle Shape As Revealed By Spectral Depolarization, Donald D. Duncan, Michael Eugene Thomas

Electrical and Computer Engineering Faculty Publications and Presentations

Through a series of numerical simulations we explore some scatter effects due to nonspherical particles. Specifically, we examine the link between the aspect ratio of randomly oriented, prolate spheroidal particles and the resulting linear depolarization of the scattered light in the forward and backscatter directions. The particular objective is to detect the presence of randomly oriented particles that have a systematic size and aspect ratio. Calculations show that the spectral behavior of the linear depolarization reveals the aspect ratio of the scattering particles. The concept is demonstrated using the size, shape, and refractive index of the spore form of Bacillus …

Coagulation Effects On Aerosol Dynamics Along An Isothermal Vertical Flat Plate, Chang-Bin Huang, Cherng-Shing Lin, Shih-Cheng Wang

Journal of Marine Science and Technology–Taiwan

Aerosol dynamic behavior in a turbulent flow field is investigated in this study. The flow field is a natural convection boundary layer flow adjacent to a heated or cooled vertical flat plate. The main computational method is based on a boundary layer type solution combining the flow field and sectional aerosol simulation. The SIMPLE alogrithm is adopted to solve the flow continuity, momentum, energy, and aerosol concentration equations. Various aerosol dynamic transport and removal mechanisms, including fluid convection, Brownian motion, gravitational settling, thermophoretic drift, and coagulation of aerosols, are considered in the simulation model. Aerosol coagulation effects on particle transport …

Optimization Of Perforated Doublelayer Absorbers Using Simulated Annealing, Min-Chie Chiu, Ying-Chun Chang, Long-Jyi Yeh, Tian-Syung Lan

Journal of Marine Science and Technology–Taiwan

As noise is highly responsible for the psychological and physiological ills to workers, the noise control for enclosed manufacturing system with sound absorber becomes obligatory; besides, considering the maintenance and operation in a room, the minimal thickness of sound absorber is certainly requested, according. To meet these issues, the compromising design target, ratio of sound absorption coefficient to thickness of acoustic panel, is thus proposed and applied as a researched objective, accordingly. In this paper, the simulated annealing (SA) is utilized in the shape optimization of the double-layer sound absorption system. The paper tackles not only the theoretical derivation in …

Design And Fabrication Of Out-Of-Plane Silicon Microneedles With Integrated Hydrophobic Microchannels, Michael S. Diehl

Theses and Dissertations

Microfabricated needles have the potential for inexpensive drug delivery without pain. The ability to deliver medication painlessly to patients will someday be not just hoped for but expected by the general public. The commercialization of this technology will also lead to other valuable technologies, such as systems that continually monitor and control insulin or other drugs in diabetic patients. This research presents fabrication procedures developed to produce pyramidal-shaped microneedles with microchannels that will allow for fluid delivery. The microchannels are etched into the substrate surface of a [100] silicon wafer using inductively coupled plasma etching. After the channel etch a …

Annealing Effects Of Semiconducting Barium-Titanate Thermister, Yeong-Chin Chen

Journal of Marine Science and Technology–Taiwan

Two Positive Temperature Coefficient of Resistivity (PTCR) ceramics with composition A, (Ba0.997Sb0.003)Ti1.005O3, and composition B, (Ba0.997Sb0.003)Ti1.005O3 + 0.1 mole% MnO2 were fabricated and examined herein. The ceramic grain size, oxygen pressure and annealing time need to be simultaneously controlled to obtain an optimum PTCR resistor. Additionally, the stoichiometric proportions of the constituent elements must be weighted carefully in order to produce good quality PTCR devices. This study thoroughly explores all the factors affecting the PTCR characteristics. Experiments were developed to verify that PTCR phenomena are strongly influenced by oxygen absorption. As the samples were annealed in Air atmosphere, the numbers …

Characteristic Study Of Mhd Pump With Channel In Rectangular Ducts, Je-Ee Ho

Journal of Marine Science and Technology–Taiwan

This study is focused on the prediction of pumping performance in MHD flow. To reach it, an analytic model based on the steady state, incompressible and fully developed laminar flow theory will be provided to analyze the flow characteristic with different scalar dimensions in duct channel. By converting the Lorentz forces which is interacted by electric current and magnetic flux into hydrostatic pressure gradient in the moment equations, the governing equations can be transformed into Poisson equation which makes the analytic solution possible. Furthermore, the concept of flow circuit which is similar to the thermal network in conduction problem will …

The Dynamics And Control Of An Moving Mass Traveling On An Initially Curved Beam, Chih-Ching Chang, Yi-Ming Wang

Journal of Marine Science and Technology–Taiwan

The objective of this paper is to study the dynamics and control of an Euler-Bernoulli beam with an attached mass rolling on an initially curved beam based on a simplified control model. The optimization of the performance index of linear quadratic regulator (LQR) is considered. Three actuators are placed along the beam that provide the necessary forces to control the response of the beam-mass system. Based on Euler-Bernoulli beam theory and Newtonian mechanics, the coupled non-linear equations of motion combining with a simple closed-loop feedback control are obtained. Results of present study show that with appropriate regulator design, the vibration …

An Analytic Analysis Of W-Cdma Smart Antennas Beamforming Using Complex Conjugate And Doa Methods, Chi-Min Li, Jia-Chyi Wu, I-Tseng Tang

Journal of Marine Science and Technology–Taiwan

Wideband Code Division Multiple Access (W-CDMA) adopts the smart antenna techniques to increase the signal-to-interferencenoise ratio (SINR) and system capacity. In this paper, we statistically derive analytic results to prove the SINR performance for the two commonly used CC and DOA beamforming methods. Results show the both methods will have the same mean SINR performance and CC method will be more robust than the DOA method.

Pole Placement Design Of Decentralized Output Feedback Power System Stabilizers Using Hybrid Differential Evolution, Yung-Sung Chuang, Chi-Jui Wu, Shu-Chen Wang, Pei-Hwa Huang

Journal of Marine Science and Technology–Taiwan

The hybrid differential evolution (HDE) has been used to investigate a novel decentralized pole placement design method of output feedback power system stabilizers. Since the local output variables are used as the feedback signals, the stabilizers could be easily implemented. In the design procedures, it wants to place the electromechanical modes within a designated region in the complex variable plane. The HDE method is originally an optimal searching approach. If all electromechanical modes have been moved to the specified region at the convergent steps, the objective function will reach zero, which is the minimum value. The objective function is chosen …

Preface, Judy Schneider, Rajiv S. Mishra, Thomas R. Bieler, Yuntian T. Zhu, Khaled B. Morsi, Viola L. Acoff, Eric M. Taleff, Ruslan Valiev

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Effects Of Surface Roughness On Porous Inclined Slider Bearings Lubricated With Micropolar Fluids, N.B. Naduvinamani, T.V. Biradar

Journal of Marine Science and Technology–Taiwan

This paper describes a theoretical analysis of the effect of surface roughness on the hydrodynamic lubrication of one-dimensional porous inclined slider bearings with micropolar fluids. To account for more realistic situations of the non-uniform rubbing of the bearing surfaces, it is assumed that, the probability density function for the random variable characterizing the surface roughness is asymmetrical with non-zero mean. The averaged modified Reynolds type equation is derived and the closed form expressions for the bearing characteristics are obtained. The numerical computations of the results show that, the performance of the porous inclined slider bearing is improved for the micorpolar …

The Assessment Of River Ecology And Habitat Using A Two-Dimensional Hydrodynamic And Habitat Model, Ray-Shyan Wu, Chen-Tai Mao

Journal of Marine Science and Technology–Taiwan

The assessment of river ecology is an integral part of river planning and management today. In any project, the simulation and quantification of river habitat and ecology is as important as the simulation of the hydrodynamics of the river. Currently in Taiwan, the use of one-dimensional models, such as Phabsim and Rhabsim, are widespread in the evaluation of river ecology and habitat. These models use data from the river cross-section and bed roughness coefficient to estimate habitat area. However, the use of these models is limited in small-scale or complex river conditions. This study applies a two-dimensional hydrodynamic and habitat …