Engineering Commons^™

Modern Technologies For Design Data Collection, James Samuel Bethel, Steven D. Johnson, Monica Prezzi, Boudewijn H. W. Van Gelder, Bob G. Mccullouch, Ali Fuat Cetin, Seungwoo Han, Mosab Hawarey, Changno Lee, Aparajithan Sampath, Jie Shan

JTRP Technical Reports

Design data collection involving the use of Lidar instrument, in conjunction with GPS proves to be very effective. Data required to model two bridges over the I-70 was collected on a single day, involving five and six sessions with Lidar equipment. Even though the data was collected on two bridges, it did not cause any disruption of the traffic, either on the Interstate or on the bridges. A major cause of concern during survey activities, particularly along interstates is safety, both for the motorists as well as the people involved in data collection. Lidar data collection was found to be …

The Application Of Advanced Solid Modelling Techniques To The Design Of Precision Air Handling Units For Manufacture, Senan Moynihan

Masters

This thesis investigates the application of ActiveX technology to customise mid range solid modelling software, with a view to exploring the benefits small to medium sized manufacturing companies can experience from its successful implementation. A custom application intended to automate solid modelling software was developed that optimises the product design process and also generates the necessary manufacturing information, including working drawings, for precision air handling units. This was successfully accomplished through research and by integrating Computer Aided Design (CAD) with a custom application using ActiveX technology. A variety of CAD products and associated technologies i.e. solid modelling kernels, were researched …

Acoustics Of The Human Middle-Ear Air Space, Cara E. Stepp, Susan E. Voss

Engineering: Faculty Publications

The impedance of the middle-ear air space was measured on three human cadaver ears with complete mastoid air-cell systems. Below 500 Hz, the impedance is approximately compliance-like, and at higher frequencies (500-6000 Hz) the impedance magnitude has several (five to nine) extrema. Mechanisms for these extrema are identified and described through circuit models of the middle-ear air space. The measurements demonstrate that the middle-ear air space impedance can affect the middle-ear impedance at the tympanic membrane by as much as 10 dB at frequencies greater than 1000 Hz. Thus, variations in the middle-ear air space impedance that result from variations …

Engineering Of Composite Media For Shields At Microwave Frequencies, Marina Koledintseva, Poorna Chander Ravva, Richard E. Dubroff, James L. Drewniak, Konstantin Rozanov, Bruce Archambeault

Electrical and Computer Engineering Faculty Research & Creative Works

Analytical and numerical modeling of composites with an isotropic dielectric base and multiphase conducting inclusions for the development of wideband microwave shields is considered. The model uses Maxwell Garnett formalism for multiphase mixtures. Such composites are required in many engineering applications, including electromagnetic compatibility.

A Hybrid Approach To Decrease Port Influence In Transmission Line Characterization, Jianmin Zhang, David Pommerenke, James L. Drewniak, Richard E. Dubroff, Zhiping Yang, Wheling Cheng, John Fisher, Sergio Camerlo

Electrical and Computer Engineering Faculty Research & Creative Works

Characterization and models for multi-gigabit signaling is an important issue in modern digital system. A good physical based model relies on a precise characterization of the test board. Typically, the characterization of the test board is associated with scattering matrix parameter measurement, which can be done with a VNA (Vector Network Analyzer) in the frequency-domain or a TDR (Time Domain Reflectometer) in the time-domain. The commonly used launch techniques on PCBs (Printed Circuit Boards) associated with the VNA or TDR measurement in the microwave frequency range use SMA or 3.5 mm connectors, in edge-launch or vertical-launch fashions. The transition between …

A Three-Dimensional Fdtd Subgridding Method With Separate Spatial And Temporal Subgridding Interfaces, Kai Xiao, David Pommerenke, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

The idea of separating the spatial and temporal subgridding interfaces is introduced in this paper. Based on this idea, the spatial and temporal subgridding algorithms can be developed and analyzed separately. The spatial algorithm was given in the previous paper. In this paper, the temporal subgridding algorithm is described and the stability is illustrated by the analytical formulation of a one-dimensional model. An FDTD code that combines the spatial and temporal subgridding algorithms is implemented. Numerical test models are calculated to show the stability and accuracy of the proposed method.

Journal Of Materials Engineering And Performance: Editorial, C. Suryanarayana, Leon L. Shaw, Rajiv S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Distance Estimation Algorithm For Stereo Pair Images, Edwin Tjandranegara

Department of Electrical and Computer Engineering Technical Reports

Various algorithms have been proposed for estimating camera distance from objects in digital stereo pair videos and images. Existing algorithms assume that digital images were taken with pan and tilt cameras or assume that the angles between the cameras and the object are known. The algorithm that we are proposing has the ability to calculate distance from the camera plane to the object plane, where the cameras do not have the ability to pan and tilt nor the angles between the cameras and the object are known beforehand.

Bs News

Building Services Engineering

No abstract provided.

Study Of Viscoelastic Effect On The Frequency Shift Of Microcantilever Chemical Sensors (Proceedings), U. Sampath, Stephen M. Heinrich, Fabien Josse, F. Lochon, Isabelle Dufour, D. Rebière

Civil and Environmental Engineering Faculty Research and Publications

Microcantilevers coated with a chemically sensitive layer are increasingly being used in chemical detection systems. The sensitive coating, often a polymer, absorbs specific molecules, which can be detected by monitoring the shift in the mechanical resonant frequency. Usually, the frequency shift resulting from molecular absorption is interpreted as a mass loading effect. However, mass loading is not the only effect that has an impact on the frequency shift; the viscoelastic properties of the sensitive coating are also affected by the sorption process. Sorption-induced modulus changes are typically difficult to characterize. However, it is known that the sorption of analyte molecules …

Manure Use Planning: An Evaluation Of A Producer Training Program, Charles S. Wortmann, Richard K. Koelsch, Charles A. Shapiro, Richard L. Deloughery, David D. Tarkalson

Department of Agricultural and Biological Systems Engineering: Faculty Publications

A training program for producers in manure use planning was evaluated. The potential for runoff nutrient loss to surface water can reduced and the value of manure increased through better planning of manure use. Training was conducted throughout Nebraska in 2002 and 2003. Livestock producers who attended evaluated the event at the end of the last class. The need for and impact of the training was greater for continuing operational and maintenance skills of manure utilization that are regularly needed for strategic planning skills. We recommend that training focus primarily on operational and maintenance skills.

Stochastic Modeling Of The Permeability Of Randomly Generated Porous Media, Yusong Li, Eugene Leboeuf, P. K. Basu, Sankaran Mahadevan

Department of Civil and Environmental Engineering: Faculty Publications

Permeability of porous media in subsurface environments is subject to potentially large uncertainties due to the heterogeneity of natural systems. In this study, a first-order reliability method (FORM) is combined with a lattice Boltzmann method (LBM) to estimate the permeability of randomly generated porous media. The proposed procedure provides an increased ease of addressing complex pore structures by employing LBM to model fluid flow, while inheriting the computational efficiency from FORM. Macroscale- equivalent permeability can thus be estimated with significantly reduced computational efforts, while maintaining a connection to the complex microscale fluid dynamics within a pore structure environment. Implemented on …

Magnetization Reversal In Particulate L10 Nanostructures, Jian Zhou, Ralph Skomski, Kory D. Sorge, David J. Sellmyer

Nebraska Center for Materials and Nanoscience: Faculty Publications

Magnetization processes in particulate L1₀ FePt nanostructures are investigated by model calculations and numerical simulations. The systems considered include anisotropic nanograins embedded in non-magnetic matrix; randomly oriented nanoclusters embedded in a C matrix, and nanocomposites of FePt particles in a semi-hard matrix. The reversal mechanisms depend on both intra- and intergranular features. Quasi-coherent rotation dominates the reversal in weakly-coupled granular magnets, but interface imperfections yield a disproportionately strong coercivity reduction. Strong intergranular exchange leads to a transition to a discrete pinning regime, which is accompanied by a coercivity maximum.

Phase Transformations And Thermodynamic Properties Of Nanocrystalline Fept Powders , J. Lyubina, O. Gutfleisch, Ralph Skomski, K.-H. Müller, L. Schultz

Nebraska Center for Materials and Nanoscience: Faculty Publications

The solid state reactions and structural evolution in nanocrystalline FePt powders during mechanical ball milling at 77 K and subsequent annealing have been investigated. Above 310 °C the formation of L1₀ FePt is observed. As the milling time increases, the enthalpy evolved during the transformations is reduced, whereas the corresponding activation energy increases. For accelerating the ordering process a fine lamellar structure of Fe and Pt is favourable.

Atomic And Micromagnetic Aspects Of L10 Magnetism, Ralph Skomski, Arti Kashyap, Jian Zhou

Nebraska Center for Materials and Nanoscience: Faculty Publications

Atomic and continuum effects in L1₀ magnets are investigated. Emphasis is on the competition between ferromagnetism, antiferromagnetism, and noncollinear order in both perfect and imperfect structures, and on the temperature dependence of the magnetic anisotropy. The applicability of micromagnetic and atomistic approaches depends on the length scales involved, but there is a broad range of phenomena where both can be used.

Cost Effective Human Protein C Purification From Cohn Fraction Iv-1 Using Mini-Antibody., Doh Gyeuhn Ahn 1969-

Electronic Theses and Dissertations

Protein C (PC) is an important anticoagulant, antithrombotic, and antiinflammatory in blood plasma. PC deficiency can lead to severe venous thrombotic events, including lung embolism, stroke, and heart attack. In the body, PC is activated only when it is needed, and, therefore, PC does not cause bleeding problems that currently available anticoagulants may do. Purification of PC from plasma is currently done by immunoaffinity chromatography using monoclonal antibodies (Mabs), which is very expensive. Single chain variable regions (mini-Mab) with a PC binding capability, which can be produced in recombinant E. coli , were developed for PC purification. Compared to Mabs, …

Comparing Material Impact Strength Of Three High Impact Plastic Resins Used In Automotive Grille Using Nonlinear Finite Element Analysis Tools, Jason Santiago

Masters Theses

As a part of Team Value Management program, existing products are benchmarked against the best in class products and their product design and manufacturing reviewed to identify ways to lower costs, such as using less expensive materials or streamlining manufacturing processes.

In this study an effort has been made to compare impact properties of three different plastic resins used in car grilles. The plastic resins being compared are a proprietary grade PC+ABS, an alternate commercial grade PC +ABS and a commercial grade ABS. The results from this study will be used to evaluate the feasibility of replacing PC+ABS with ABS …

Modeling, Fabrication, And Optimization Of Niobium Cavities Final Phase: Final Report, Robert A. Schill Jr., Mohamed Trabia, William Culbreth

Transmutation Sciences Materials (TRP)

This final report provides the activities and accomplishments of Modeling, Fabrication, and Optimization of Niobium Cavities – Final Phase. The fluid flow experiments for the etching of the superconducting cavity walls and baffle designs of phase II of the three phases has been completed leading to a MS thesis in December of 2003. Designing the experimental setup of secondary electron emission was well underway in early summer of 2003 when funding was made available for this portion of the study. By March 2004, many of the components of the experimental study reached UNLV with some assembly accomplished. The first secondary …

Decentralized Perimeter Surveillance Using A Team Of Uavs, Timothy Mclain, Randal W. Beard, Derek Kingston, Ryan S. Holt, David W. Casbeer

Faculty Publications

This paper poses the cooperative perimeter-surveillance problem and offers a decentralized solution that accounts for perimeter growth (expanding or contracting) and insertion/deletion of team members. By identifying and sharing the critical coordination information and by exploiting the known communication topology, only a small communication range is required for accurate performance. Simulation and hardware results are presented that demonstrate the applicability of the solution.

On Optimization Of Sensor Selection For Aircraft Gas Turbine Engines, Ramgopal Mushini, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Many science and management problems can be formulated as global optimization problems. Conventional optimization methods that make use of derivatives and gradients are not, in general, able to locate or identify the global optimum. Sometimes these problems can be solved using exact methods like brute force. Unfortunately, these methods become computationally intractable because of multidimensional search spaces. Hence, the application of heuristics for a class of problems that incorporates knowledge about the problem helps solve optimization problems. Optimization of sensor selection using heuristics can lead to significant improvements in the controllability and observability of a dynamic system. The aim of …

Evaluation Of Time-Varying Availability In Multi-Echelon Inventory System With Combat Damage, Hoong Chuin Lau, Huawei Song

Research Collection School Of Computing and Information Systems

The models for multi-echelon inventory systems in existing literatures predominantly address failures due to reliability in peacetime. In wartime or even peacetime operational scenarios, unexpected combat damage can cause a large number of systems to be heavily damaged, to the extent that they become irreparable. In this paper, we study a multi-echelon spare parts support system under combat damage, discuss the replenishment policy and propose an approximate method to evaluate the time-varying system performance operational availability considering the effect of passivation. Experiments show our model works well and efficiently against simulation.

Tuning Tabu Search Strategies Via Visual Diagnosis, Steven Halim, Wee Chong Wan, Hoong Chuin Lau

Research Collection School Of Computing and Information Systems

While designing working metaheuristics can be straightforward, tuning them to solve the underlying combinatorial optimization problem well can be tricky. Several tuning methods have been proposed but they do not address the new aspect of our proposed classification of the metaheuristic tuning problem: tuning search strategies. We propose a tuning methodology based on Visual Diagnosis and a generic tool called Visualizer for Metaheuristics Development Framework(V-MDF) to address specifically the problem of tuning search (particularly Tabu Search) strategies. Under V-MDF, we propose the use of a Distance Radar visualizer where the human and computer can collaborate to diagnose the occurrence of …

Effects Of Mutual Coupling On Interference Mitigation With A Focal Plane Array, Michael A. Jensen, Karl F. Warnick

Faculty Publications

A focal plane array feed of electrically small elements has been proposed as a means for achieving high sensitivity for radio astronomy applications in the presence of radio frequency interference (RFI). For a broadband system, mutual coupling effects become significant as the array element spacing becomes small relative to the electromagnetic wavelength. We present a theoretical framework for modeling the effects of mutual coupling and for determining the optimal multiport matching network between array elements and front-end transistor low-noise amplifiers for maximum signal-to-noise ratio (SNR). Numerical results are given for a model scenario including spillover and amplifier thermal noise and …

Study Of Secondary Electron Emission From Niobium At Cryogenic Temperatures, Anoop George

UNLV Theses, Dissertations, Professional Papers, and Capstones

The objective of this project is to study the properties of secondary electron emission from niobium samples, cleaned at the Los Alamos National Laboratory, at cryogenic temperatures to enhance existing multipacting codes with data on the samples. The predominant cause of power loss in radio-frequency superconducting accelerators cavities is multipacting. This project studies the secondary electron distribution from niobium metal due to incident primary electrons. The experiments on the niobium sample are performed in an environment close to that present in a superconducting accelerator cavity.

The experiment is performed in a vacuum chamber capable of achieving ultra high vacuum levels …

Microfocal X-Ray Computed Tomography Post-Processing Operations For Optimizing Reconstruction Volumes Of Stented Arteries During 3d Computational Fluid Dynamics Modeling, John F. Ladisa, Lars E. Olson, Kristina M. Ropella, Robert C. Molthen, Steven Thomas Haworth, Judy R. Kersten, David C. Warltier, Paul S. Pagel

Biomedical Engineering Faculty Research and Publications

Restenosis caused by neointimal hyperplasia (NH) remains an important clinical problem after stent implantation. Restenosis varies with stent geometry, and idealized computational fluid dynamics (CFD) models have indicated that geometric properties of the implanted stent may differentially influence NH. However, 3D studies capturing the in vivo flow domain within stented vessels have not been conducted at a resolution sufficient to detect subtle alterations in vascular geometry caused by the stent and the subsequent temporal development of NH. We present the details and limitations of a series of post-processing operations used in conjunction with microfocal X-ray CT imaging and reconstruction to …

Dispatching Vehicles In A Mega Container Terminal, Ebru K. Bish, Frank Y. Chen, Thin Yin Leong, Barry L. Nelson, Jonathan W. C. Ng, David Simchi-Levi

Research Collection School Of Computing and Information Systems

We consider a container terminal discharging and uploading containers to and from ships. The discharged containers are stored at prespecified storage locations in the terminal yard. Containers are moved between the ship area and the yard using a fleet of vehicles, each of which can carry one container at a time. The problem is to dispatch vehicles to the containers so as to minimize the total time it takes to serve a ship, which is the total time it takes to discharge all containers from the ship and upload new containers onto the ship. We develop easily implementable heuristic algorithms …

Design And Characterization Of A Dual-Stage, Thermally Actuated Nanopositioner, Neal B. Hubbard, Larry L. Howell

Faculty Publications

A nanopositioner is presented that has two stages for independent coarse and fine position control. Thermal microactuators operate both stages. The first stage includes a bistable mechanism: it travels 52 micrometers between two discrete positions. The second stage is mounted on the first stage and moves continuously through an additional 8 micrometers in the same direction as the first stage. Three approaches to the control of the second stage were evaluated in terms of accuracy and manufacturability, and one was selected for the design of the nanopositioner. The device was surface micromachined in a two-layer polysilicon process. Experiments were performed …

Sequential Labelling And Acoustic Emission Analysis Of Damage Occurring In Cortical Bone During Indentation Cutting, Ger Reilly, Ashkan Safari, David Taylor, Brendan Mccormack

Conference Papers

When a surgeon uses a wedge shaped blade or an osteotome to cut cortical bone during an operative procedure the bone will fail by a process of microcracking and primary crack propagation. It has previously been observed that crack propagation is dependent on the direction of cutting relative to the main axis of the bone. It has also been observed that microcracks occurring during fracture release acoustic signals that facilitate real-time monitoring of a cutting process. In these novel studies, we labelled damage accumulation during cutting of cortical bone using sequential chelating dyes and we correlated recorded AE signals during …

47th Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 47th annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-endorsed by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, July 31 - August 4, 2005.

Study Of System Parameters And Control Design For A Flexible Manipulator Using Piezoelectric Transducers, Mehrdad Kermani Ph.D., P.Eng., Mehrdad Moallem, Rajni Patel

Electrical and Computer Engineering Publications

No abstract provided.