Engineering Commons^™

Metal Modulation Epitaxy Growth For Extremely High Hole Concentrations Above 10(19) Cm(-3) In Gan, Gon Namkoong, Elaissa Trybus, Kyung Keun Lee, Michael Moseley, W. Alan Doolittle, David C. Look

Applied Research Center Publications

The free hole carriers in GaN have been limited to concentrations in the low 10¹⁸ cm⁻³ range due to the deep activation energy, lower solubility, and compensation from defects, therefore, limiting doping efficiency to about 1%. Herein, we report an enhanced doping efficiency up to ~10% in GaN by a periodic doping, metal modulation epitaxy growth technique. The hole concentrations grown by periodically modulating Ga atoms and Mg dopants were over ~1.5 x 10¹⁹ cm⁻³.

© 2008 American Institute of Physics.

Temperature Dependence Of A Macrobending Edge Filter Based On A High-Bend Loss Fiber, Pengfei Wang, Ginu Rajan, Yuliya Semenova, Gerald Farrell

Articles

The temperature dependence of a macrobending bare fiber based edge filter is investigated both theoretically and experimentally. The fiber used is a high bend loss fiber, type 1060XP. The experimental results show a good agreement with the proposed theoretical model over a temperature range from 0 to 80oC. It is shown that the strong temperature dependence of a high-bend loss fiber has a significant influence on the performance of a fiber edge filter used in a wavelength measurement application. However it is also concluded that such a temperature dependent performance can be beneficially utilized in a fiber temperature sensing application.

Improved Duct Systems Task Report With Stagegate 2 Analysis, Florida Solar Energy Center, Neil Moyer

FSEC Energy Research Center®

The Building America Industrialized Housing Partnership's work with two industry partners, Cavalier Homes and Southern Energy Homes, in constructing and evaluating prototype interior duct systems will be summarized. Issues of energy performance, comfort, DAPIA approval, manufacturability and cost will be addressed. A stage gate 2 analysis will address the current status of project showing that there are still refinements needed to the process of incorporating all of the ducts within the air and thermal boundaries of the envelope.

Soft Ground Improvement By Vacuum-Assisted Preloading, Cholachat Rujikiatkamjorn, Buddhima Indraratna

Faculty of Engineering - Papers (Archive)

This paper describes the behaviour of soft soil foundation stabilized with vacuum-assisted preloading at the New Bangkok International Airport, Thailand. An analytical solution considering the variation of soil permeability and compressibility and a finite element analysis based on an equivalent plane strain model developed by the authors are employed to investigate the performance of the test embankment. The converted equivalent plane strain parameters are incorporated in the finite element code ABAQUS. The associated settlement, excess pore pressure and lateral movement are predicted and compared with the available field measurement. The data indicate that the efficiency of the prefabricated vertical drains …

Orange County Convention Center Energy Analysis And Energy Information System, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

The Orange County Convention Center (OCCC) has the 2nd largest convention facility utilization in the nation. Two primary buildings provide about seven million square feet of conditioned space to approximately 1.5 million visitors per year. In efforts to reduce energy conservation, OCCC began implementing several energy conservation measures beginning in 2005 and continuing over the last 2 years with plans to continue additional efforts in the future. An analysis of monthly chilled water and electricity used by the West and North/South Buildings has been completed in an effort to investigate reductions in energy use resulting from conservation measures. This final …

Effect Of Sparger Design On Hydrodynamics Of A Gas Recirculation Anaerobic Bioreactor, Rajneesh Varma, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Effects of Sparger Design and Gas Flow Rate On, Gas Holdup Distribution and Liquid (Slurry) Recirculation Velocity Have Been Studied in a Surrogate Anaerobic Bioreactor Used for Treating Bovine Waste with a Conical Bottom Mixed by Gas Recirculation. a Single Orifice Sparger (SOS) and a Multi-Orifice Ring Sparger (MORS) with the Same Orifice Open Area and Gas Flow Rates (Hence the Same Process Power Input) Are Compared in This Study. the Advanced Non-Invasive Techniques of Computer Automated Tomography (CT) and Computer Automated Radioactive Particle Tracking (CARPT) Were Employed to Determine Gas Holdup, Liquid Recirculation Velocity, and the Poorly Mixed …

N-Glycan Modification In Aspergillus Species, Elke Kainz, Andreas Gallmetzer, Christian Hatzl, Juergen H. Nett, Huijuan Li, Thorsten Schinko, Robert Pachlinger, Harald Berger, Yazmid Reyes-Dominguez, Andreas Bernreiter, Tillmann Gerngross, Stefan Wildt, Joseph Strauss

Dartmouth Scholarship

The production by filamentous fungi of therapeutic glycoproteins intended for use in mammals is held back by the inherent difference in protein N-glycosylation and by the inability of the fungal cell to modify proteins with mammalian glycosylation structures. Here, we report protein N-glycan engineering in two Aspergillus species. We functionally expressed in the fungal hosts heterologous chimeric fusion proteins containing different localization peptides and catalytic domains. . This strategy allowed the isolation of a strain with a functional -1,2-mannosidase producing increased amounts of N-glycans of the Man 5 GlcNAc 2 type. This strain was further engineered by the introduction of …

Nirt: Developing A Nanoscale Sensing Device For Measuring The Supply Of Iron To Phytoplankton In Marine Systems, Mark L. Wells, Karen Orcutt, D. Whitney King, Carl Tripp

University of Maine Office of Research Administration: Grant Reports

There is increasing evidence that Fe has a singularly unique role in marine ecosystems, both regulating total phytoplankton production in high nitrate, low chlorophyll regions of the world, and influencing the predominant composition of the phytoplankton assemblages found in others. It is remarkable then that there is no agreement about how to define biologically available Fe, in contrast to the macronutrients nitrogen, phosphorous or silicon. Current attempts to attain predictive insights to how ocean ecosystems will influence the magnitude of climate change are blocked in large part by this question, along with an extreme shortage of data on Fe distributions …

Relative Intensity Noise Study In The Injection-Locked Integrated Electroabsorption Modulator-Lasers, Xiaomin Jin, Bennet Yun Tarng, Shun Lien Chuang

Electrical Engineering

No abstract provided.

A High Power, High Efficiency Amplifier Using Gan Hemt, Bumjin Kim, Dennis Derickson, Cheng Sun

Electrical Engineering

A class B and a class F power amplifier are described using a GaN HEMT device. They both were designed to operate at a frequency of 1.7 GHz with the same bias conditions. The performances of each amplifier were successfully simulated and compared. A class B amplifier was physically implemented and achieved a high power-added-efficiency of 69.2%, 39.9 dBm output power and associated gain of 14.9 dB. The experimental results were in close agreement to the simulation results.

Ceas E-News 12.11.2007, College Of Engineering And Applied Sciences

College of Engineering and Applied Sciences News

Winners of 2007 Spring AutoCAD Contest honored in fall lecture class

Causey, Robert Lewis, B. 1927 (Sc 1316), Manuscripts & Folklife Archives

MSS Finding Aids

Finding aid only for Manuscripts Small Collection 1316. Comments written by Causey, Bowling Green, Kentucky, concerning the proposed industrial Trimodal Transpark that would be located near Smiths Grove, Kentucky, if approved.

The Effect Of Contact Length On Adhesion Between Carbon Nanotubes On Silicon Dioxide, Robert C. Davis, Kaylee Mcelroy, Aaron R. Hopkins

Faculty Publications

The force of adhesion was measured for single walled carbon nanotubes grown over lithographically defined silicon dioxide trenches. We varied contact lengths between the nanotubes and silicon dioxide from 230 to 850 nm. Suspended nanotubes were pushed vertically into the trenches with an atomic force microscope tip, causing them to slip along the surface. Previous work done at shorter contact lengths found that tension was constant with contact length [J. D. Whittaker et al., Nano Lett. 6, 953 (2006)]. This study finds that when the nanotube contact length approaches 1 µm, the tension at which nanotubes slip begins to increase …

Vacuum Consolidation Effects On Lateral Yield Of Soft Clays As Applied To Road And Railway Embankment, Buddhima Indraratna, Cholachat Rujikiatkamjorn, G. Mcintosh, A. Balasubramaniam

Faculty of Engineering - Papers (Archive)

The use of vertical drains with vacuum preloading is considered as the most effective and economical method for improving soft clays (normally consolidated to lightly over-consolidated) to eliminate settlements of the permanent infrastructure. Application of vacuum pressure via prefabricated vertical drains promotes radial flow consolidation enhancing the shear strength of the compressed ground. In this paper, the mechanisms of the vacuum preloading system based on current practices are described through the selection of the important design parameters. The equivalent plane strain solution for both Darcian and non-Dracian flow are presented to predict the excess pore pressures, lateral and vertical displacements. …

College Of Engineering Senior Design Competition Fall 2007, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge.

The senior design competition helps to focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects …

Numerical Simulation Of Gas-Solid Dynamics In A Circulating Fluidized-Bed Riser With Geldart Group B Particles, S. Vaishali, Shantanu Roy, Satish Bhusarapu, M. (Muthanna) H. Al-Dahhan, M. P. Dudukovic

Chemical and Biochemical Engineering Faculty Research & Creative Works

Circulating Fluidized-Bed (CFB) Risers with Geldart Group B Particles Have Found Significant Application in Combustion Reactions. the Present Work Attempts to Study the Solids Flow Dynamics in a CFB Riser that is Operated with Group B Particles, using Computational Fluid Dynamics (CFD) Techniques. the Key Feature in the Present Study is that the Various Closure Schemes in the CFD Model Have Been Evaluated Against Data from Non-Invasive Experimental Techniques: Computer Automated Radioactive Particle Tracking (CARPT) for Solids Velocity Field and Computed Tomography (CT) for Solids Holdup. Since Solids Flow in a Riser is Multiscale in Character, in Addition to the …

System For Sequentially Providing Aberation Corrected Electromagnetic Radation To A Spot On A Sample At Multiple Angles Of Incidence, Martin M. Liphardt, John A. Woollam,

Department of Electrical and Computer Engineering: Faculty Publications

A system for sequentially providing electromagnetic radia tion to a spot on a sample at different angles of incidence, and after reflection therefrom into a detector. The system includes a plurality of spherical mirrors, and a refractive element for correcting aberration.

Rotating Or Rotatable Compensator Systemi Providing Aberation Corrected Electromagnetic Raadation To A Spot On A Sample At Multiple Angles Of Ancidence, Martin M. Liphardt, Blaine D. Johs, Jeffrey S. Hale, Craig M. Herzinger, Steven E. Green, Ping He, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

The present invention relates to ellipsometer systems, and more particularly to ellipsometer systems comprising trans missive rotating or stepwise rotatable compensators for continuously or step-wise varying polarization states and further comprising transmissive multi-element lens focusing of a spectroscopic electromagnetic beam into a small, chromatically relatively undispersed area spot on a sample system. The ellipsometer system optionally is present in an environmental control chamber.

Ceas E-News 12.04.2007, College Of Engineering And Applied Sciences

College of Engineering and Applied Sciences News

Social gathering offers welcome to CEAS international students

Buffer Law And Transitional Roughness Effect In Turbulent Open-Channel Flows, Junke Guo, Pierre Y. Julien

Department of Civil and Environmental Engineering: Faculty Publications

A novel and complete velocity profile law is presented for turbulent open channel flows. The law embeds the linear law in the viscous sublayer; the quartic law due to turbulent bursting that must satisfy instantaneous mass conservation, the modified log-wake law in the outer region and the effects of wall roughness. Specifically, an arctangent law smoothly connects the linear law with the log law of the wall. Combining the arctangent law with the modified log-wake law, a continuous velocity profile is proposed for smooth boundary conditions. A complete velocity profile is obtained after subtracting a new roughness function. Finally, the …

Commissioners Report On The Shoals In The Ohio River (Sc 1545), Manuscripts & Folklife Archives

MSS Finding Aids

Finding aid and full-text scan (Click on "Additional Files" below) for Manuscripts Small Collection 1545. Photocopy (made in 1970) of handwritten Ohio River survey done in 1819 related to river navigation in Ohio, Kentucky, Virginia, and Indiana. It includes many hand-drawn maps. There is a large, undated map in a pocket on inside back cover.

). Size Dependency Of The Elastic Modulus Of Zno Nanowires: Surface Stress Effect, Guofeng Wang, Xiaodong Li

Faculty Publications

Relation between the elastic modulus and the diameter (D) of ZnOnanowires was elucidated using a model with the calculated ZnOsurface stresses as input. We predict for ZnOnanowires due to surface stress effect: (1) when D>20nm, the elastic modulus would be lower than the bulk modulus and decrease with the decreasing diameter, (2) when 20nm>D>2nm, the nanowires with a longer length and a wurtzite crystal structure could be mechanically unstable, and (3) when D<2nm, the elastic modulus would be higher than that of the bulk value and increase with a decrease in nanowire diameter.

The Tri-Frame Model, Elsje Pienaar, Hendrik J. Viljoen

Hendrik J. Viljoen Publications

The tri-frame model gives mathematical expression to the transcription and translation processes, and considers all three reading frames. RNA polymerases transcribe DNA in single nucleotide increments, but ribosomes translate mRNA in pairings of three (triplets or codons). The set of triplets in the mRNA, starting with the initiation codon (usually AUG) defines the open reading frame (ORF). Since ribosomes do not always translocate three nucleotide positions, two additional reading frames are accessible. The -1RF and the +1RF are triplet pairings of the mRNA which are accessed by shifting one nucleotide position in the 5’ and 3’ directions respectively. Transcription is …

Response Of Phlebotomine Sand Flies To Light-Emitting Diode-Modified Light Traps In Southern Egypt, D. F. Hoel, Emad Y. Fawaz, J.E Butler, N. Watany, S. S. El-Hossary, J. Villinski

U.S. Navy Research

Centers For Disease Control and Prevention (CDC) light traps were modified for use with light-emitting diodes (LED) and compared against a control trap (incandescent light) to determine the effectiveness of blue, green, and red lights against standard incandescent light routinely used for sand fly surveillance. Light traps were baited with dry ice and rotated through a 4 x 4 Latin square design during May, June, and July, 2006. Trapping over 12 trap nights yielded a total of 2,298 sand flies in the village of Bahrif, 6 km north of Aswan on the east bank of the Nile River in southern …

Variability In Compression Strength And Deflection Of Corrugated Containers As A Function Of Positioning, Operators, And Climatic Conditions, Jay A. Singh, P. Bainbridge, S. P. Singh, Eric Olsen

Industrial Technology and Packaging

ASTM D642 is a commonly used standard for measuring the ability of containers to resist external compressive loads applied to its faces, to diagonally opposite edges, or to corners. The procedure recommends testing by centering the specimen on the lower platen of the testing machine in the desired orientation, so as not to incur eccentric loading. It is also recommended by the standard that the load be applied with a continuous motion of the movable platen of the testing machine at a speed of 0.5 ±0,1 in. (12.7 ± .25 cm)/min until failure or a specified load, has been reached. …

Measurement And Analysis Of Vibration Levels On Warehouse And Retail Store Material Handling Equipment, S. P. Singh, Jay A. Singh, P. Gaur, K. Saha

Industrial Technology and Packaging

Material Handling Equipment (MHE) is widely used to move packaged goods from manufacturing to warehousing, storage, transportation, in both warehouses and distribution centers to retail stores. Moving product between facilities is done by different types of equipment ranging from manually pushed carts to automated vehicles. A considerable amount of research has been conducted to evaluate the ergonomics of manual or mechanized MHE in the past. There is, however, no published work documenting vibration conditions that occur when transporting packages using MHE. This study measured the vibration levels for typical MHE used at warehousing facilities. Power spectral density plots were generated …

An Examination Of The Variables Affecting Rfid Tag Readability In A Conveyer Belt Environment, Jay A. Singh, C. Deupser, Eric Olsen, S. P. Singh

Industrial Technology and Packaging

There is a growing list of companies implementing radio frequency identification (RFID) systems to help optimize their supply chain processes. These companies realize that a successful RFID system can potentially lead to lower supply chain inventory levels, reduced operating expenses, and greater visibility throughout the supply chain. However, since RFID technology is still relatively immature, a majority of the applications experience less than perfect read rates for tagged items moving through the supply chain. This paper reports the results for a variety of different arrangements of variables that may influence the readability of the RFID tags in a conveyer belt …

Life Cycle Aware Computing: Reusing Silicon Technology, John Y. Oliver, Rajeevan Amirtharajah, Venkatesh Akella, Roland Geyer, Frederic T. Chong

Electrical Engineering

Despite the high costs associated with processor manufacturing, the typical chip is used for only a fraction of its expected lifetime. Reusing processors would create a "food chain" of electronic devices that amortizes the energy required to build chips over several computing generations.

Efficiency Study Of Adjustable Speed Drive With Dual Motor Connection, C. Mitsui, S. Tu, Taufik, M. Anwari

Electrical Engineering

This paper presents a study of AC adjustable speed drive when used to operate two induction motors. The impact of running the two motors under various loading conditions and operating output frequency to overall efficiency of the adjustable speed drives under room temperature will be discussed. Data obtained from laboratory and their analysis will be presented

Evaluation Of Current Nonlinear Static Procedures For Concrete Buildings Using Recorded Strong-Motion Data, Rakesh K. Goel, Charles Chadwell

Civil and Environmental Engineering

This study evaluates current Nonlinear Static Procedures (NSPs) specified in the FEMA356, ASCE-41, ATC-40, and FEMA-440 documents using strong-motion data from reinforced-concrete buildings. For this purpose, three-dimensional computer models of five reinforced concrete buildings – Imperial County Services Building, Sherman Oaks Commercial Building, North Hollywood Hotel, Watsonville Commercial Building, and Santa Barbara Office Building – are developed. When appropriate, springs at the building’s base are included to account for the soil-structure interaction effects. These buildings are selected because they were strongly shaken, several deformed beyond their linear-elastic range, during past earthquakes and their recorded motions are available. The recorded motions …