Physical Sciences and Mathematics 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.

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 …

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 …

). 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.

Minerva 2007, The Honors College

Minerva

This issue of Minerva includes an article on the hiring of first-ever full-time Honors faculty members, Mimi Killinger and Mark Haggerty; an article on Honors alumna Molly Barker '00; and a reflection by former Honors Program Director Sam Schuman.

Evaluation Of Robocode As A Teaching Tool For Computer Programming, Arnold Hensman

Conference Papers

Robocode began as an educational tool to aid in learning Java programming. It has since evolved into something of a phenomenon, as the prospect of creating simple to complex virtual tanks appears to pose an attractive challenge to both novice and expert programmers alike. What started out as a teaching tool has grown into a worldwide network of competitors, all keen to prove that their ‘bot’ stands out from the crowd. Competitions are well organised and many Robocode events are a PR dream for the computing companies that sponsor them. Without a doubt, this easy to use application has sparked …

Fabrication Of Robust Superconducting Granular Aluminium/Palladium Bilayer Microbolometers With Sub-Nanosecond Response, Thomas E. Wilson

Physics Faculty Research

We provide a convenient recipe for fabricating reliable superconducting microbolometers as acoustic phonon detectors with sub-nanosecond response, using imagereversal optical lithography and dc-magnetron sputtering, and our recipe requires no chemical or plasma etching. Our approach solves the traditional problem for granular aluminium bolometers of unreliable (i.e., non-Ohmic) electrical contacts by sequentially sputtering the granular aluminium film and then a palladium capping layer. We use dc calibration data, the method of Danilchenko et al. [1], and direct nanosecond-pulsed photoexcitation to obtain the microbolometer’s characteristic current, thermal conductance, characteristic relaxation time, and heat capacity. We also demonstrate the use of the deconvolution …

A Fast Image Super-Resolution Algorithm Using An Adaptive Wiener Filter, Russell C. Hardie

Electrical and Computer Engineering Faculty Publications

A computationally simple super-resolution algorithm using a type of adaptive Wiener filter is proposed. The algorithm produces an improved resolution image from a sequence of low-resolution (LR) video frames with overlapping field of view. The algorithm uses subpixel registration to position each LR pixel value on a common spatial grid that is referenced to the average position of the input frames. The positions of the LR pixels are not quantized to a finite grid as with some previous techniques. The output high-resolution (HR) pixels are obtained using a weighted sum of LR pixels in a local moving window. Using a …

Technical Evaluation Of Hardwood Biorefinery Using The "Near-Neutral" Hemicellulose Extraction Process, Haibo Mao

Electronic Theses and Dissertations

A technical analysis was performed for a new process that produces ethanol and acetic acid from hardwood in addition to bleached hardwood Kraft pulp. The new process, termed the "near neutral" hemicellulose extraction process, involves the extraction of wood hemicellulose using green liquor prior to conventional Kraft pulping. This thesis assumes that the new process is located at an existing kraft pulp mill. Ancillary unit operations in the process include hydrolysis of the extracted carbohydrates using sulfuric acid, filtration of the extract to remove lignin that was extracted with the carbohydrates, liquid-liquid extraction of acetic acid and by-product furfural, liming …

What Is Rcu, Fundamentally?, Paul E. Mckenney, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Read-copy update (RCU) is a synchronization mechanism that was added to the Linux kernel in October of 2002. RCU achieves scalability improvements by allowing reads to occur concurrently with updates. In contrast with conventional locking primitives that ensure mutual exclusion among concurrent threads regardless of whether they be readers or updaters, or with reader-writer locks that allow concurrent reads but not in the presence of updates, RCU supports concurrency between a single updater and multiple readers. RCU ensures that reads are coherent by maintaining multiple versions of objects and ensuring that they are not freed up until all pre-existing read-side …

Study Of The Minimum Spanning Hyper-Tree Routing Algorithm In Wireless Sensor Networks, Ting Yang, Yugeng Sun, Zhaoxia Wang, Juwei Zhang, Yingqiang Ding

Research Collection School Of Computing and Information Systems

Designing energy-efficient routing protocols to effectively increase the networks' lifetime and provide the robust network service is one of the important problems in the research of wireless sensor networks. Using the hyper-graph theory, the paper represents large-scale wireless sensor networks into a hyper-graph model, which can effectively decrease the control messages in routing process. Based on this mathematic model, the paper presents the minimum spanning hyper-tree routing algorithm in synchronous wireless sensor networks (MSHT-SN), which builds a minimum energy consumption tree for data collection from multi-nodes to Sink node. The validity of the algorithm is proved by the theatrical analysis. …

Tuning Tabu Search Strategies Via Visual Diagnosis, Steven Halim, 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 …

Self-Organizing Neural Architectures And Cooperative Learning In A Multiagent Environment, Dan Xiao, Ah-Hwee Tan

Research Collection School Of Computing and Information Systems

Temporal-Difference–Fusion Architecture for Learning, Cognition, and Navigation (TD-FALCON) is a generalization of adaptive resonance theory (a class of self-organizing neural networks) that incorporates TD methods for real-time reinforcement learning. In this paper, we investigate how a team of TD-FALCON networks may cooperate to learn and function in a dynamic multiagent environment based on minefield navigation and a predator/prey pursuit tasks. Experiments on the navigation task demonstrate that TD-FALCON agent teams are able to adapt and function well in a multiagent environment without an explicit mechanism of collaboration. In comparison, traditional Q-learning agents using gradient-descent-based feedforward neural networks, trained with the …

Trends In Uspto Office Actions, Ron D. Katznelson

Ron D. Katznelson

No abstract provided.

Practical Sensor For Measurement Of Nitrogen, Dusan Popovic, Vladimir Milosavljevic, Steven Daniels

Articles

This paper presents a method for precise measurement of atomic and molecular nitrogen in an oxygen-nitrogen dc plasma. This is achieved by monitoring the intensities of the atomic nitrogen spectral line at 821.6 nm and the molecular nitrogen bandhead at 337.1 nm, relative to the atomic oxygen spectral line at 844.7 nm. Oxygen is one of the most frequently used gases for surface chemical treatment, including deposition and etching, therefore the ability to measure and control the process and chemical composition of the process is essential. To validate this oxygen actimometry method for N2-xO2 (where x varies from 0 to …

Electrochemical Oxidization Of Herring Sperm Dna And Its Interaction With Histone, Juan Xu, Gui-Ping Huang, Hong Li, Wei Zhu

Journal of Electrochemistry

The voltammetric behavior of herring sperm DNA at glassy carbon electrode and its interaction with histone have been investigated by using cyclic voltammetry,differential pulse voltammetry,and fluorescence measurement.In the potential range of 0.20 V to 1.25 V,it is found that an irreversible oxidative peak is exhibited in acid solution,but in the neutral or alkaline solution two oxidative peaks are observed.Oxidative peak potential values show a negative shift with increasing pH via a slope of-57 mV·pH-1 and a linear relation with DNA concentration in the range of 0.45 to 8.20 mmol·L-1.In the presence of histone,the oxidative peak current of DNA and the …

Eiectro-Oxidation Of Methanol On Pdnio/C Catalyst In Alkaline Medium, Mei-Li Wang, Lin Sang, Cheng-De Huang

Journal of Electrochemistry

The electro-oxidation of methanol in alkaline electrolyte at in-house synthesized PdNiO/C and Pd/C catalysts and the effect of heat treatment on the structure and performance of catalysts were studied by cyclic voltammetry,chronoamperometry,chronopotentiometry and X-ray diffraction methods.It is shown that when the reduction temperature is 70℃ and the ratio between Pd and Ni is 8∶2,The PdNiO/C catalyst presents a highest activity for methanol electrooxidation.Calcining can increase the particle size and crystallinity of catalysts,but decrease the dispersion and activity of catalysts, too.Besides,the NiO is disengaged from Pd lattice by heat-treatment.The optimal PdNiO/C catalyst shows higher catalytic activity and much better poisoning resistance …

Study On Electrochemical Impedance Spectroscopy Of Carbon Steel Eroded In Methyldiethanolamine Solution, Dong-Ping Wei, Rong-Zong Hu, Dan-Mei Pan, Wei-Xiong Huang, Rui Dong

Journal of Electrochemistry

Corrosion behavior of carbon steel in methyldiethanolamine(MDEA) solution was investigated by Electrochemical Impedance Spectroscopy(EIS).The results were showed that the corrosion rate of carbon steel in solution containing dissolved oxygen is higher than that in solution removed of dissolved oxygen before cathodic activation.They were reversed after cathodic activation.The corrosion rate is increased at first and then decreased when the concentration of MDEA is increased in the blank solutions.In the simulated solutions containing quantities of!heat-stable salts(HSS),the corrosion rate is decreased monotonously with increase of the MDEA concentration.As anodic polarization potential is increased,the EIS of carbon steel in HSS simulated solution showed characteristics …

Electrochemical Behavior Of Zinc Alloy Anode In Ca(Oh)_2 Solutions Of Different Ph, Peng-Ying Ren, Ji-Quan He

Journal of Electrochemistry

The polarization curves of zinc alloy anodes in Ca(OH)2 solutions have been measured by potentiodynamic method,and the composition of corrosion products were examined by X-ray-diffraction(XRD).The experimental results indicated that not only the electrochemical behavior of zinc alloy anodes were absolutely different in every alkaline solutions,but also many electrochemical parameters were determined,such as zero current potential(E0),the density of corrosion current(icorr),passive current density(ip),breakdown potential(Eb),and so on.There were three zero current potential when zinc alloy anodes in some Ca(OH)2 solutions which made passive state unstable.The graphs of E-pH about zinc alloy anodes dipped in different Ca(OH)2 solutions were drawn,and compared with the potential-pH …

Study On The Corrosion Of Chlorine Condenser By Electrochemical Method, Bin Xiang, Wen Chen, Wen-Zhang Huang, Shao-Hua Xing, Sheng-Tao Zhang

Journal of Electrochemistry

Corrosion of condenser is very seriously in chlorine-alkali industry,which could lead to fatal disaster.The most commonly used material in low pressure condenser includes steel of 16MnR,10#,and welding rod of J507.Electrochemical analysis of the three materials in 29.9%(by mass) calcium chloride(CaCl2) solution was carried out.The corrosion current density icorr and impedance parameters of the three materials in 29.9% CaCl2 solution were estimated separately.The result showed that in the tripartite phase regions where the 10# seamless tube and 16MnR armor plate were jointed by welding,the weld was firstly eroded and suggested that the chlorine condenser should be examined and repaired every year.

Electrochemical Behavor Of Zinc-Indium Alloy Electrodes In Concentrated Alkaline Solution, Zhi-Lin Wang, Xiao-Ge Zhang, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

The electrochemical behavior of zinc-indium alloy electrodes in 35%KOH solutions has been investigated by electrochemical methods including the potentiodynamic polarization and discharge measurements under constant current density.The results indicate that the anodic current density and passive current density increase after the indium addition.The discharge measurement shows that the addition of indium shortens the time to passive state for the Zn alloy compared to pure zinc at a large discharge conditions,that is the addition of indium may enhance the electrochemical activity of Zn alloy electrodes.It is found that the anodic dissolution of zinc-indium alloy electrodes in the concentrated KOH solution occurs …

Preparation And Properties Of High Capacity Lifepo_4, Jun Li, Gui-Tang Lai, Hui-Min Huang, Da-Guang Li, Xin-De Xia

Journal of Electrochemistry

Carbon-doped LiFePO4/C and pure phase LiFePO4 cathode materials were prepared by liquid-state precipitation reaction.The results of XRD,SEM,elemental analysis,FTIR and A.C.impedance tests show that the samples have had olivine structure and a 3.4V discharge platform.The tapped density of LiFePO4/C sample could reach 1.46g/cm3,the initiate discharge capacity is 144.6mAh/g at 0.1C,which remained capacity is 93.2% after 20 cycles.The first discharge capacity is 133.5mAh/g at 1C and the capacity decreased 8.76% after 20 cycles.

Research Of 2,2′-Dipyridine On Electroless Copper Plating Using Sodium Hypophosphite As Reductant, Bin Yang, Fang-Zu Yang, Ling Huang, Shu-Kai Xu, Guang-Hua Yao, Shao-Min Zhou

Journal of Electrochemistry

In the bath of the electroless copper plating using sodium hypophosphite as reductant,the effects of 2,2′-dipyridine on the deposition rate,anodic oxidation of sodium hypophosphite,cathodic reduction of copper ions,surface morphologies,structure and the existing status of the deposit components were examined.The results showed that,2,2′-dipyridine hindered the electroless deposition.Experiments of liner sweep voltammetry(LSV) indicated that,as the addition of 2,2′-dipyridine to the electrolyte,the oxidation peak potential of sodium hypophosphite shifted to a more negative value but the peak current decreased;the reducing peak potential of copper ions moved to a more negative value whereas the peak current increased.Scanning electron microscope(SEM)、energy dispersive spectroscopy(EDS)、X-ray diffraction(XRD) and X-ray …

Electrochemical Behavior And Determination Of Luteolin At A Glassy Carbon Electrode, Ai-Lin Liu, Shao-Bo Zhang, Xiao-Sha Wu, Li-Ping Li, Yang-Yuan Cao, Li-Ying Huang, Xin-Hua Lin

Journal of Electrochemistry

The electrochemical behavior of luteolin was studied by voltammetry at a glassy carbon electrode in phosphate buffer solution.The results exhibited that the well-defined redox peak of luteolin is observed and the electrode process is adsorption-controlled.The charge transfer coefficient(α) was calculated as 0.66 in phosphate buffer solution(pH 4.0).The relationships between oxidation peak current and the concentration of luteolin are linear in the range of 1.0×10-8 ～ 5.0×10-6 mol·L-1 by differential pulse voltammetric method.The detection limit had been estimated as 1.0×10-8 molL-1.This method can be used for the determination of luteolin with satisfactory results.

Selection Of Additions In The Process Of Electrochemical Synthesizing Of K_2feo_4, Wei-Hua Yang, Dong-Qin Bi, Yan Zhou, Hong-Hui Wang, Xin-Ren Lan

Journal of Electrochemistry

Some of different additions including KIO4 was added to the anodic electrolyte for electrochemical synthesizing of K2FeO4,the effects of these additions on current yield were investigated.XRD and SEM were used to characterize the structure and image of K2FeO4.The results show that KIO4 is a preferable addition.When the mass dosage of KIO4 is 0.02%,electrolysis time is 1 h,the current yield is enhanced by 31.6% and the corresponding purity of the product is improved by 3.85 %.

Preparation And Investigations On The Tio2nanotube Arrays For Cathodic Protection Of 316l Stainless Steel, Jing Li, Hong Yun, Chang-Jian Lin

Journal of Electrochemistry

A highly ordered TiO2nanotube layer was fabricated by potentiostatic anodization of pure titanium in fluorinated electrolyte solutions.The structure and composition of the as-prepared TiO2 nanotubes were characterized by SEM and XRD.The TiO2 nanotubes show a stronger absorption in the ultraviolet(UV) light range.The performances of photogenerated cathodic protection and the photoelectrochemical response for the TiO2 nanotube layers under illumination and dark conditions were evaluated through the electrochemical measurements.It is found that the open-circuit potentials of 316 SS coupled with the TiO2 nanotubes layers shift negatively under UV light irradiation(λ<380nm).It is indicated that the TiO2 nanotubes arrays are able to function effectively a photogenerated cathodic protection for metals under light illumination and keep the cathodic protection for a long time under dark conditions.

Ion-Implanting Modification Of Layered Manganese Dioxide And Its Electrochemical Performance, He-Ning Huang, Dong-Ping Lv, Xing-Kang Huang, Qi-Wei Zhang, Yong Yang

Journal of Electrochemistry

Layered MnO2(δ-MnO2) was prepared by thermal decomposition of potassium permanganate.Ti was ion-implanted into such δ-MnO2 by physical techniques,forming a composite(δ-MnO2-Ti).These materials were characterized by XRD,SEM,XPS techniques and their electrochemical proprieties were investigated.The results showed that the layered structure of δ-MnO2 did not been destroyed after Ti ion implantation,and the implanted Ti element was mainly Ti4+ as indicated by XPS.Both of the first and the highest discharge specific capacities of the ion-implanted layered MnO2(δ-MnO2-Ti),compared to those of δ-MnO2,were improved significantly.

Determination Of Malathion Based On Carbon Nanotubes Modified Electrode Incorporating Acetylcholinesterase, Lu Zhang, Yao-Dong Zhang, Hong-Lan Qi

Journal of Electrochemistry

A biosensor for determination of organophosphorus pesticide based on the acetylcholinesterase and multi-wall carbon nanotubes modified electrode is fabricated.Under the optimal conditions,the chronoamperometric current at +0.70V(vs.SCE) increased linearly with the concentration of malathion in the range from 6.0×10-10 to 6.0×10-9 mol·L-1 with a detection limit of 1.0×10-10 mol·L-1.The recoveries of malathion in lake water is 97% to 105% determinated by this method.

High-Speed Three-Dimensional Shape Measurement System Using A Modified Twoplus- One Phase-Shifting Algorithm, Song Zhang, Shing-Tung Yau

Song Zhang

This paper describes a high-resolution, real-time, three-dimensional shape measurement system using the modified two-plus-one phase-shifting algorithm. The data acquisition speed is as high as 60frames∕s with an image resolution of 640×480pixels per frame. Experiments demonstrated that the system was able to acquire the dynamic changing objects such as facial geometric shape changes when the subject is speaking, and the modified two-plus-one phase-shifting algorithm can further alleviate the error due to motion. Applications of this system include manufacturing, online inspection, medical imaging, compute vision, and computer graphics.

Nevada Risk Assessment/Management Program – Phase 2 (Nramp2): Quarterly Progress Report July 1, 2007 Through September 30, 2007, Klaus J. Stetzenbach

Nevada Risk Assessment/Management Program

Work conducted in this 4th quarter consisted of 3 major activities:

• Continue the receipt and reconciliation of Area 5 Radioactive Waste Management Site (RWMS) inventory data.

• Receive, review, install, calibrate, and run the Goldsim Area 5 Performance Assessment (PA) Model, and review the supporting parameters and assumptions in the 93-document reference set as a tool for regulatory compliance and closure assessment.

• Identify, review, and compare the interpretation of pertinent regulatory guidelines and orders by DOE sites in compliance for PA, Compliance Assessment (CA), and closure activities - as they may relate to the Nevada Test Site (NTS) …