Physical Sciences and Mathematics Commons^™

Matching And Fairness In Threat-Based Mobile Sensor Coverage, Chris Y. T. Ma, Jren-Chit Chin, David K.Y. Yau, Nageswara S. Rao, Mallikarjun Shankar

Department of Computer Science Technical Reports

No abstract provided.

Evaluating Variance Of The Model Credibility Index, Yan Xiao

Mathematics Theses

Model credibility index is defined to be a sample size under which the power of rejection equals 0.5. It applies goodness-of-fit testing thinking and uses a one-number summary statistic as an assessment tool in a false model world. The estimation of the model credibility index involves a bootstrap resampling technique. To assess the consistency of the estimator of model credibility index, we instead study the variance of the power achieved at a fixed sample size. An improved subsampling method is proposed to obtain an unbiased estimator of the variance of power. We present two examples to interpret the mechanics of …

Scandium Oxide Thin Films And Their Optical Properties In The Extreme Ultraviolet, Guillermo Antonio Acosta

Theses and Dissertations

This study reports on the physical and optical characterization of scandium oxide thin films. Thin films of scandium oxide, 20-40 nm thick, were deposited on silicon wafers, quartz slides, and silicon photodiodes by reactively sputtering scandium in an oxygen environment. These samples were characterized using ellipsometry, high-resolution transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive x-ray analysis. A 28.46 nm thick scandium oxide thin film was measured in the Extreme Ultraviolet (EUV) from 2.7 to 50 nm (459.3 to 24.8 eV) using synchrotron radiation at the Advanced Light Source Beamline 6.3.2 at the Lawrence Berkeley National Laboratory. In …

Clustering Methods For Delineating Regions Of Spatial Stationarity, Jared M. Collings

Theses and Dissertations

This paper seeks to further investigate data extracted by the use of Functional Magnetic Resonance Imaging (FMRI) as it is applied to brain tissue and how it measures blood flow to certain areas of the brain following the application of a stimulus. As a precursor to detailed spatial analysis of this kind of data, this paper develops methods of grouping data based on the necessary conditions for spatial statistical analysis. The purpose of this paper is to examine and develop methods that can be used to delineate regions of stationarity. One of the major assumptions used in spatial estimation is …

Modeling Transition Probabilities For Loan States Using A Bayesian Hierarchical Model, Rebecca Lee Monson

Theses and Dissertations

A Markov Chain model can be used to model loan defaults because loans move through delinquency states as the borrower fails to make monthly payments. The transition matrix contains in each location a probability that a borrower in a given state one month moves to the possible delinquency states the next month. In order to use this model, it is necessary to know the transition probabilities, which are unknown quantities. A Bayesian hierarchical model is postulated because there may not be sufficient data for some rare transition probabilities. Using a hierarchical model, similarities between types or families of loans can …

Analysis And Implementation Of High-Order Compact Finite Difference Schemes, Jonathan G. Tyler

Theses and Dissertations

The derivation of centered compact schemes at interior and boundary grid points is performed and an analysis of stability and computational efficiency is given. Compact schemes are high order implicit methods for numerical solutions of initial and/or boundary value problems modeled by differential equations. These schemes generally require smaller stencils than the traditional explicit finite difference counterparts. To avoid numerical instabilities at and near boundaries and in regions of mesh non-uniformity, a numerical filtering technique is employed. Experiments for non-stationary linear problems (convection, heat conduction) and also for nonlinear problems (Burgers' and KdV equations) were performed. The compact solvers were …

Education In The Environment: A Strategy For Continued Interagency Outdoor Education Programming: Quarterly Progress Report, Period Ending November 30, 2007, Environmental Education Strategy For Nevada

Reports (PLI Education)

During the past three months, the focus of the university’s efforts has included the following highlights:

• Progress was made on three projects to meet SNAP strategic messaging needs: an anti-litter exhibit; a volunteer restoration program with educational components; and activity stations to tell the story of Lee Meadows restoration efforts.
• Interpretive planning is underway for Mountain’s Edge Explorer’s Interpretive Trail.
• A Spanish class tailored to meet the communication needs of environmental educators and interpreters will be offered January 2008.
• Forever Earth was scheduled for 15 days and benefited 411 individuals.
• Eight Discover Mojave Outdoor World events were conducted for 102 …

A Direct Algorithm For The K-Nearest-Neighbor Classifier Via Local Warping Of The Distance Metric, Tohkoon Neo

Theses and Dissertations

The k-nearest neighbor (k-NN) pattern classifier is a simple yet effective learner. However, it has a few drawbacks, one of which is the large model size. There are a number of algorithms that are able to condense the model size of the k-NN classifier at the expense of accuracy. Boosting is therefore desirable for increasing the accuracy of these condensed models. Unfortunately, there does not exist a boosting algorithm that works well with k-NN directly. We present a direct boosting algorithm for the k-NN classifier that creates an ensemble of models with locally modified distance weighting. An empirical study conducted …

The Rotation Period Of The Planet-Hosting Star Hd 189733, Gregory W. Henry, Joshua N. Winn

Information Systems and Engineering Management Research Publications

We present synoptic optical photometry of HD 189733, the chromospherically active parent star of one of the most intensively studied exoplanets. We have significantly extended the timespan of our previously reported observations and refined the estimate of the stellar rotation period by more than an order of magnitude: P = 11.953 ± 0.009 days. We derive a lower limit on the inclination of the stellar rotation axis of 54° (with 95% confidence), corroborating earlier evidence that the stellar spin axis and planetary orbital axis are well aligned.

2007 Fall Engr333/Biol354 Project Solutions Poster, 2007 Fall Engr333, 2007 Fall Biol354

ENGR 333

A carbon footprint is term which refers to the net amount of greenhouse gases produced to directly or indirectly by human activities and is usually expressed in terms of metric tons of carbon dioxide. The Calvin community places a strong emphasis on practicing good stewardship, including stewardship of Creation. Reducing Calvin’s carbon footprint is crucial because carbon dioxide is a major greenhouse gas and contributes heavily to global climate change. In a previous portion of this project, the carbon footprint of Calvin College was calculated to be about 66,400 MTCE (Metric Tons Carbon dioxide Emitted). The goal of this portion …

2007 Fall Engr333/Biol354 Project Footprint Poster, 2007 Fall Engr333, 2007 Fall Biol354

ENGR 333

The students of Calvin College’s Engineering 333 and Biology 354 classes were given the task of determining “What would it take to make Calvin College Carbon Neutral?” At first glance, it would not appear that classes on Advanced Thermal System Design and Investigations in Plant Ecology would have much in common. However, the biology and engineering students comprising these classes banded together to tackle the problem. Coming to a satisfactory conclusion would require: Creating an inventory of Green House Gas (GHG) emissions and sequestration potential Coming up with detailed solutions to achieve Carbon Neutrality Working out a practical schedule to …

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 …

Electrochemical Behavior Of Dill Pipe In 31%(By Mass)Nacl Solution Based New Type Inhibitor, Fu-Guo Liu, Min Du, Qing-Zhang Wang

Journal of Electrochemistry

The inhibitive effect of compound inhibitor including emulsifier(P)、zinc sulfate、sodium polyphosphate、Glucose Gluconate was studied in 31% NaCl(bymass) solution.The inhibitory mechanism was analyzed by polarization curve and EIS.The results showed that the compound inhibitor was anodic-type inhibitor and its inhibitive effect on anodic and cathodal reaction was the most obvious at 200×10-6g·L-1.And the results of EIS revealed that the inhibition efficiency increased and the film formed on electrode surface was more and more compact with time.Inhibition mechanism was different with concentration of inhibitor.

A New Method To Reduce The Contact Resistance Between Metal Current Collector And Graphite Plate For Pemfc, Hao Sun, Ming Han, Meng-Kai Liu, Jun-Bo Jia, Yao-Tian Zhan

Journal of Electrochemistry

A new method to reduce the contact resistance between metal current collector and graphite plate for PEMFC has been proposed.It was found that the contact resistance between the stainless steel current collector and graphite plate after embedding a metal net-carbon polymer composition is effective by to eliminate,Fuel cell testing has presented that this new method can effectively reduce the internal resistance of PEMFC,and improve the performance of the PEM fuel cell.

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 %.

Construction Of Three-Dimensional Finite Element Model For Complicated Cathodic Protection System, Ai-Ping Wang, Min Du, Qing-Zhang Wang, Sheng-Shan Cao, Ji-Xing Sun

Journal of Electrochemistry

When condensers with carbon steel waterbox and titanium tube structure were protected by SACP in an ocean beach power plant,while seawater were used to be cooling water,carbon steel was under-protected and Titanium was over-protected,because their protective potential are less than-0.85V(vs.SCE) and more than-0.75V(vs.SCE) separately.In order to optimize the SACP design,potential distribution of two materials must be obtained during the SACP process.In the lab,carbon steel waterbox and Titanium tube model(Q235-Ti model) were set up.A series of electrochemical techniques(steady polarization,galvanostatic charge technique)were used to obtain reasonable boundary condition and surface form of two materials during the SACP process.The experiments were carried out …

Study On Metal|Solid Electrolyte|Gel Membrane Containing Water|Graphite System, Jing-Dong Liu

Journal of Electrochemistry

The characteristic of oxide layer formed on the surface of metal in Metal|Solid Electrolyte|Gel Membrane Containing Water|Graphite System was studied by using Point Defect Model and Barrier Layer/Porous Layer Model.Trace water in solid electrolyte helped to form porous layer at the surface of metal,The thickness of porous layer increased due to water molecule reacts with barrier layer continuously,which lowered the porosity and decreased the electromotive potential and current.Porosity influenced solubility behavior of oxide layer intensely.Like barrier layer,porous layer is also a semiconductor.

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.

Voltammetric Behavior Of Rutin And Its Application, Zong-Yao Qian, Bing-Qi Li, Hong Liu, Xin-Fu Xia, Yin-Mei Wang, Ya-Ping Niu

Journal of Electrochemistry

In solution of 0.1mol/L Tris-HCl(pH=8.3),a sensitive reduction peak of rutin was obtained by liner sweep polarography.The peak potential was-1.10V(vs.Ag/AgCl).The peak current was proportional to the concentration of rutin over the range of 7×10-7～9.8×10-6mol/L.This method has been applied to the determination of the flavonoid in G.Uralensis.The results showed that the reduction process was irreversible with adsorption that studied by linear sweep and cyclic voltammetry.

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.