Engineering Commons^™

On-Demand Key Distribution For Mobile Ad-Hoc Networks, Daniel F. Graham

Theses and Dissertations

Mobile ad-hoc networks offer dynamic portable communication with little or no infrastructure. While this has many benefits, there are additional shortcomings specific to wireless communication that must be addressed. This research proposes gossip-based on-demand key distribution as a means to provide data encryption for mobile ad-hoc networks. This technique uses message keys to avoid encrypting and decrypting a message at every node. Other optimizations used include secure channel caching and joint rekey messages. The use of gossip makes the scheme robust to node failure. Experimental results show only a 15% increase in end-to-end delay with a node failure rate of …

Recommendations For A Standardized Program Management Office (Pmo) Time Compliance Network Order (Tcno) Patching Process, Michael Czumak Iii

Theses and Dissertations

Network security is a paramount concern for organizations utilizing computer technology, and the Air Force is no exception. Network software vulnerability patching is a critical determinant of network security. The Air Force deploys these patches as Time Compliance Network Orders (TCNOs), which together with associated processes and enforced timelines ensure network compliance. While the majority of the network assets affected by this process are Air Force owned and operated, a large number are maintained by external entities known as Program Management Offices (PMOs). Although these externally controlled systems provide a service to the Air Force and reside on its network, …

Modeling, Simulation, And Estimation Of Optical Turbulence, Byron P. Formwalt

Theses and Dissertations

This dissertation documents three new contributions to simulation and modeling of optical turbulence. The first contribution is the formalization, optimization, and validation of a modeling technique called successively conditioned rendering (SCR). The SCR technique is empirically validated by comparing the statistical error of random phase screens generated with the technique. The second contribution is the derivation of the covariance delineation theorem, which provides theoretical bounds on the error associated with SCR. It is shown empirically that the theoretical bound may be used to predict relative algorithm performance. Therefore, the covariance delineation theorem is a powerful tool for optimizing SCR algorithms. …

Efficient Algorithms For Machine Scheduling Problems With Earliness And Tardiness Penalties, Guang Feng, Hoong Chuin Lau

Research Collection School Of Computing and Information Systems

In this paper, we study the multi-machine scheduling problem with earliness and tardiness penalties and sequence dependent setup times. This problem can be decomposed into two subproblems—sequencing and timetabling. Sequencing focuses on assigning each job to a fixed machine and determine the job sequence on each machine. We call such assignment a semi-schedule. Timetabling focuses on finding an executable schedule from the semi-schedule via idle-time insertion. Sequencing is strongly NP-hard in general. Although timetabling is polynomial-time solvable, it can become a computational bottleneck if the procedure is executed many times within a larger framework. This paper makes two contributions. We …

Studies On The Ion Conductive Performance Of Composite Polymer Electrolyte Containing Nano-Scale Sio2, Lin Ye, Yu-Mei Zhao, Xiao-Wen Zhang, Zeng-Guo Feng, Ying Bai, Feng Wu

Journal of Electrochemistry

Nano-silicon oxide was doped into a novel comblike polyether,poly(3-(methoxy(triethylenoxy))methyl-3'-methyloxetane) to prepare a series of composite polymer electrolyte.The ion conductivity measurement revealed that the composite polymer electrolyte added with 5% weight fraction of SiO₂ has the highest ion conductivity of 7.8×10^-5 S/cm at 30℃ and 4.5×10^-4 S/cm at 80℃,which is increased 30%~60% as compared to the polymer electrolyte without adding any SiO₂.DSC results implied that the nano-silicon oxide inserts into the macromolecule chains to increase the free volume and decrease the glass transition temperature to enhance the ion conductivity.In addition,it seems that the crystallization occurred due …

Preparation And Lithium Storage Performance Of Nano-Structural Sno2/Carbon Nanotubes Composite Electrodes, Hong-Bing Wei, Ling Huang, Xiao-Bin Wu, Fu-Sheng Ke, Jin-Shu Cai, Xiao-Yong Fan, Fang-Zu Yang, Shi-Gang Sun

Journal of Electrochemistry

The Nano-structural SnO₂/Carbon Nanotubes Composites were prepared in a solution of SnCl₂,ethylene glycol(EG),purified MWCNTs and sodium dodecyl sulfate(SDS) at 160 ℃.The phase structure and surface morphology of the composites were measured by XRD HRTEM and SEM.The results indicate that there are high dispersions and high loadings of SnO₂ nanoparticles on MWCNTs.Electrochemical lithium storage performance was studied preliminarily on the obtained samples.MWCNTs modified with SnO₂ nanoparicles were shown to have a higher electrochemical reversible capacity than that of MWCNTs during the charge and discharge process.MWCNTs can accommodate the larger structure strain of the active materials …

Effect Of 2,2'-Dipyridyldipyridyl And K4Fe(Cn)6 On Electroless Copper Plating Using Glyoxylic Acid As Reducing Agent, Dan-Dan Shen, Fang-Zu Yang, Hui-Huang Wu

Journal of Electrochemistry

The electroless copper plating was studied in a bath consisting of glyoxylic acid as reducing agent,Na₂EDTA as complexing agent,both 2,2'-dipyridyl and K₄Fe(CN)₆ as additives,focused on the influence of the additives on the deposition rate,as well as on the composition,structures and surface morphology of the deposits.It was found that adding an optimum amount of 2,2'-dipyridyl and K₄Fe(CN)₆ to the bath will not only improve the stability of the bath,but also increase the deposition rate by 100 %.The simultaneous addition of both additives causes the deposits to bright appearance and the change in morphology.The …

Effects Of Direct Current Bias Potentials On Lipid Membranes Forming On A Glassy Carbon Electrode, Yu-Hui Li, Hong-Wei Zhang, Gui-Lan Song, Zhan-Jun Zhang, Sheng-Min Cai

Journal of Electrochemistry

The effects of direct current(DC) bias voltage on the structure of lipid membranes forming on a glassy carbon electrode(GCE) was investigated by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS).The experiment showed that the lipid membranes can be formed with either positive or negative bias potential exerted.When bias voltage was exerted,bilayer lipid membranes tended to form due to the electrostatic interaction between the superficial positive charges on the polarized electrode and the negative charged part of PC.When the positive bias voltage overrun the range,the lacunas on s-BLMs would increase,and the BLMs would be broken.A proper equivalent circuit was nonlinearly fitted,based on the …

Charge-Discharge Behaviors And Properties Of A Lab-Scale All-Vanadium Redox-Flow Single Cell, Ping Zhao, Hua-Min Zhang, Yue-Hua Wen, Bao-Lian Yi

Journal of Electrochemistry

An experimental setup with two external saturated calomel reference electrodes(SCE)and two flow cells was established for flow battery research application.By using this setup,the cell voltage,potentials and open circuit potentials of the positive and negative electrodes for a lab-scale flow battery single cell,could be determined simultaneously during charge-discharge(C-D) cycle test.Then,the ohmic internal resistance drop(iR drop),overpotentials at the negative and positive electrodes of the cell during C-D process,were calculated.The average iR drop accounts for about 74% of the total voltage losses during the C-D cycle at current density of 60 mA·cm^-2,suggesting the voltage efficiency(VE) of vanadium redox-flow battery(VRB) single cell …

Composite Electroplating And Characterizations Of Sn-Sba15 Anode For Lithium-Ion Batteries, Xiao-Yong Fan, Jin-Mei Xu, Quan-Chao Zhuang, Hong-Hong Jiang, Ling Huang, Yan-Xia Jiang, Quan-Feng Dong, Shi-Gang Sun

Journal of Electrochemistry

Sn-SBA15 anode was prepared by composite electroplating. The first discharge and charge capacity was 1075mAh/g and 630mAh/g respectively. After fifty charge/discharge cycles, the charge and discharge capacity of Sn-SBA15 were retained above 400mAh/g. XRD patterns indicated that the Sn-SBA15 has tetragonal crystal type. SEM images showed that the Sn-SBA15 had a honeycombed surface. EIS results indicated that there was SEI film formed on the surface of Sn-SBA15 electrode.

Ac Impedance Study On The Bcx Cells, Hong-Hua Ge, Jun Wang, Jing Liu, Guo-Ding Zhou, Yi-Ping Wu, Gang Wu

Journal of Electrochemistry

The electrodes in both Li/SOCl₂ cells and BCX cells were studied by ac impedance spectroscopy.The results indicate that the resistance of the electrode passive layer increased with the storage time,then became stabilized in both kinds of cells.But the electrode resistance decreased a lot after adding BrCl into the cells.The resistance of the Li electrode decreased about a half to that without BrCl,and the value of the glassy carbon electrode decreased from about 100 kΩ to 2 kΩ.The huge resistance of the glassy carbon electrode indicates that it is the control electrode of the cell.

Comparison Of The Electrochemical Reactivity Of Electrodes Modified By Carbon Nanotubes With Different Sizes, Guo-Feng Yang, Neng-Qin Jia, Zhi-Yong Wang

Journal of Electrochemistry

The electrochemical activity of multi-walled carbon nanotubes(MWNTs) with different sizes,including four different MWNTs with the same length and different diameter,two different MWNTs with the same diameter and different length has been assessed and compared.The various MWNTs modified electrodes were prepared by immobilizing the suitable amount of MWNTs onto a glassy carbon electrode,and their voltammetric responses to ferricyanide,uric acid and dopamine were examined.The corresponding cyclic voltammetric data was showed that the electrochemical and electrocatalytic activities are depended on the nanotube length.The electrochemical reactivity of short MWNT(S-MWNT) is better than that of long MWNT(L-MWNT),which may be mainly attributed to the existence of …

Mwnts Modified Gc Electrode For Hydrogen Peroxide Determination, Hong-Juan Wang, Chun-Mei Zhou, Hao Yu, Feng Peng, Jin-Kun Fang

Journal of Electrochemistry

A MWNTs modified GC electrode was constructed successfully to be used to detect hydrogen peroxide.Two methods of maximum anodic current of cyclic voltommogram and chronoamperometry were adopted to measure the concentration of hydrogen peroxide.The results show that the MWCNTs can enlarge the effective surface area of GC electrode and can enormously enhance the electron transfer.The sensitivity and correlation coefficient for hydrogen peroxide detection are 2.84 μA/mmol·L^-1,0.997 and 1.5 μA/mmol·L^-1,0.971 for cyclic voltammetry and chronoamperometry,respectively.The procedure of the two methods to detect hydrogen peroxide is simple,and the results obtained are satisfied.

Influence Of Electrolyte On The Preparation And Electrocatalytic Properties Of Pt/Gc Electrodes, Sheng-Pei Chen, Yan-Xin Chen, Tao Huang, Xiao-Wen Hou, Shi-Gang Sun

Journal of Electrochemistry

Influence of electrolyte on the electrocatalytic properties of Pt/GC electrodes for formic acid oxidation were studied by using cyclic voltammetry, SEM and electrochemical in situ FTIR spectroscopy. It has demonstrated that the surfaces of Pt/GC electrodes prepared in H₂SO₄ (Pt/GC1) or in HClO₄(Pt/GC2) are all composed of platinum particles, but which crystals are some differences in size and shape.Diameters of platinum particles on the surface Pt/GC1 are of 100~200 nm, and with spheral shape in the majority. The sizes of platinum particles on the Pt/GC2 electrode are larger in general,part of particles is of cube …

Study On The Electrochemical Machining Of Titanium Alloys Tc4 With The Method Of Uniform Design, Mei-Li Zhang, Di Zhu, Zheng-Yang Xu

Journal of Electrochemistry

For the electrochemical machining of titanium alloys,a passivating film tends to form on the machining surface,which holdbacks the process of machining;and some corrosive pittings can appear on the non-machining surface,which leading to the poor surface quality.So how to improve the machining surface quality,this is a hot problem in aerospace industries.An experiment plan has been made with the method of uniform design and the variance analysis has been carried out using the result data of the previous experiments.The experimental results show that an excellent machining surface with Ra 0.38 μm would be obtained in the electrolyte of 10% NaCl solution,4% Na …

Investigations On Edlcs Using Pmma-Based Gel Polymer Electrolytes, Xiang-Li Meng, Jin-Ling Yin, Juan Ren, Bao-Hong Zhang

Journal of Electrochemistry

Polymethyl methacrylate(PMMA) based gel polymer electrolytes electrochemical double layer capacitors(GPE-EDLCs) were fabricated by an in situ polymerisatonal method with actived carbon electrodes,using propylene carbonate(PC) and ethylene carbonate(EC) as plasticizer,lithion perchlorate as surporting electrolytes.The ion conductivity values of GPEs were evaluated by AC impedance.The properties of PMMA-based GPEs capacitors were researched by impedance spectrum,cyclic voltammetry,galvanostatic charge-discharge.It showed that the ion conductivities of the PMMA-based gel polymer electrolytes reached to 3.7 mS·cm^-1 at ambient tempreture.The working voltage of the capacitors reached to 3.0 V.The specific capacitance of the capacitor was obtained as high as 41.6 F·g^-1(I=1 mA·cm^-2).The …

Electrochemical Characteristics Of La0.7-XCeXMg0.3Ni2.4Co0.6(X=0～0.4) Hydrogen Storage Alloys, Ling-Ling Xiao, Yi-Jing Wang, Yi Liu, Jian-Sheng Cao, Da-Wei Song, Li-Fang Jiao, Hua-Tang Yuan

Journal of Electrochemistry

The effect of partial substitution of Ce for La on the structure and the electrochemical properties of the La_0.7-xCe_xMg_0.3Ni_2.4Co_0.6(x=0～0.4)hydrogen storage alloys have been investigated systematically.The result of X-ray powder diffraction(XRD) show that the alloys are all consisted of the LaNi₃ phase and the LaNi₅ phase.The maximum discharge capacity is decreased gradually with increase of the Ce contents,but the cycling life is improved obviously.

Fabrication And Performance Of Ni-Scsz Cermet Anode Modified By Coating With Gd0.2Ce0.8O2 For A Sofc, Ren-Zhu Liu, Bo Huang, Xiao-Feng Ye, Shao-Rong Wang, Jia-Di Cao, Huai-Wen Nie, Ting-Lian Wen

Journal of Electrochemistry

A Ni-scandia-stabilized zirconia(Ni-ScSZ) cermet anode modified by coating with nano-sized gadolinium-doped ceria(GDC,Gd_0.2Ce_0.8O₂) was prepared using a simple combustion process for the solid oxide fuel cell(SOFC) running on methane fuel. X-ray diffraction(XRD) and scanning electron microscopy(SEM) indicated that the surface of Ni-ScSZ was coated by nano-sized GDC particles(<100nm). Single cell testing showed that the 2.0%(by mass) GDC-coated Ni-ScSZ anode had better performance. The highest power densities of the cell with this anode were 825 and 848mW/cm² at 850℃ in humidified hydrogen and methane, respectively, whereas the corresponding values were 584 and 586mW/cm² for the cell with Ni-ScSZ anode.Electrochemical impedance spectra(EIS) illustrated that the cell with Ni-ScSZ anode exhibited far greater impedances than the cell with 2.0%(by mass) GDC-coated Ni-ScSZ anode.Then the …

Electrochemical Oxidation Of The Phenol In The Chloride System, Yong Liu, Dan Liu, Shi-Lin Zhao, Jing-Jing Lai

Journal of Electrochemistry

The Ru-Ir /Ti electrode as cathode to electrolysis the synthetic phenolic wastewater was studied. The effect of the initial chloride concentration on the electrolytic treatment result has been discussed. Experiment result shows that the electrochemical oxidation of phenol suits to one kinetics equation in given electrolytic time. If the initial chloride concentration in wastewater increases, the time of the electrochemical oxidation of phenol can be shorten, in other words the apparent rate constant is greater. The middle matters of electrochemical oxidation of phenol in the chloride system detected out by HPLC and GC-MS is mainly 1-chloro-phenol, 4-chloro-phenol, 2,4-dichloro-phenol, 2,6-dichloro-phenol, 2,4,6-trichloro-phenol, …

Diamond-Like-Carbon Film Prepared On Stainless Steel Substrates By Liquid Phase Electrochemical Deposition, Jing-Yong Du, Gui-Feng Zhang, Guo-Qing Li, Xiao-Duo Hou

Journal of Electrochemistry

Diamond-like carbon (DLC) films were deposited on stainless steel substrates at atmospheric pressure and low temperature (60 ℃) by electrolysis in a methanol solution with a pulseddirect current power supply. The morphology and microstructure of the resulting DLC films were analyzed using atomic force microscopy(AFM), scanning electron microscopy (SEM), Raman spectroscopy and Fourier transformation infrared spectrometry (FTIR). The experimental results show that the hydrogenated diamond-like carbon filmsare smooth and compact. Raman spectroscopy analysis confirmed the presence of a strongpeak at 1332.51 cm^-1, which is assigned to crystalline diamond. The deposition rate can be enhanced to 0.5 μm/h by …

The Influence Of Electrolytic Conditions On Synthesis Of Feo42-, Yan Zhou, Wei-Hua Yang, Dong-Qin Bi, Ting-Ting Huang, Zhen Sun, Quan-Feng Guo

Journal of Electrochemistry

The FeO₄^2-was synthesized using iron lattice as anode and the solid K₂FeO₄ was also prepared.Influence of electrolytic conditions,such as stir,ultrasonic,temperature and current density on the current efficiency were studied.The results showed that preferable ferrate(VI) current yield was obtained in a current density of 10 mA·cm^-2,temperature 30 ℃ and 14 mol/L NaOH as electrolyte under at stirring effect.

Variable Frequence Switching Power Supply Used To Aluminum Foil Corrosion, Xiang-Dong Zhuo, Lan Sun, Guo-Qing Qian, Chang-Jian Lin

Journal of Electrochemistry

A new variable frequence and multi-wave power supply used to aluminum foil corrosion is introduced. The switching supply power supply controlled by the microcontroller and Variable Frequence in low band and multi-wave, big power supply controlled by the electronic switch bridge for changing phase were designed. This power supply does not need bulky and cumbersome transformer, and the frequency at lower limit is not limited, even lower than 1Hz.

Quarter-Wave Layers With 50% Reflectance For Obliquely Incident Unpolarized Light, R. M.A. Azzam, F. F. Sudradjat

Electrical Engineering Faculty Publications

The conditions under which light interference in a transparent quarter-wave layer of refractive index n1 on a transparent substrate of refractive index n2 leads to 50% reflectance for incident unpolarized light at an angle φ are determined. Two distinct solution branches are obtained that correspond to light reflection above and below the polarizing angle, φp , of zero reflection for p polarization. The real p and s amplitude reflection coefficients have the same (negative) sign for the solution branch φ>φp and have opposite signs for the solution branch φ<φp . Operation at φ<φp is the basis of a 50%–50% beam splitter that divides an incident totally polarized light beam (with p and s components of equal intensity) into reflected and …

Performance Evaluation For Hybrid Architectures, Praveen Krishnamurthy

All Computer Science and Engineering Research

In this dissertation we discuss methologies for estimating the performance of applications on hybrid architectures, systems that include various types of computing resources (e.g. traditional general-purpose processors, chip multiprocessors, reconfigurable hardware). A common use of hybrid architectures will be to deploy coarse pipeline stages of application on "suitable" compute units with communication path for transferring data. The first problem we focus on relates to the sizing the data queues between the different processing elements of an hybrid system. Much of the discussion centers on our analytical models that can be used to derive performance metrics of interest such as, throughput …

Towards Efficient Planning For Real World Partially Observable Domains, Pradeep R. Varakantham

Research Collection School Of Computing and Information Systems

My research goal is to build large-scale intelligent systems (both single- and multi-agent) that reason with uncertainty in complex, real-world environments. I foresee an integration of such systems in many critical facets of human life ranging from intelligent assistants in hospitals to offices, from rescue agents in large scale disaster response to sensor agents tracking weather phenomena in earth observing sensor webs, and others. In my thesis, I have taken steps towards achieving this goal in the context of systems that operate in partially observable domains that also have transitional (non-deterministic outcomes to actions) uncertainty. Given this uncertainty, Partially Observable …

Lake Whatcom Model Calibration With Variable Stoichiometry In Sediments - Revised, Chris Berger, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

This memorandum discusses model calibration and enhancements made to the Lake Whatcom water quality model. Model development and initial calibration were documented in the report “Lake Whatcom Water Quality Model” (Berger and Wells, 2005). The Lake Whatcom water quality model has been converted from CE-QUAL-W2 version 3.2 to version 3.5 (Cole and Wells, 2006).

Mining Generalized Associations Of Semantic Relations From Textual Web Content, Tao Jiang, Ah-Hwee Tan, We Wang

Research Collection School Of Computing and Information Systems

Traditional text mining techniques transform free text into flat bags of words representation, which does not preserve sufficient semantics for the purpose of knowledge discovery. In this paper, we present a two-step procedure to mine generalized associations of semantic relations conveyed by the textual content of Web documents. First, RDF (resource description framework) metadata representing semantic relations are extracted from raw text using a myriad of natural language processing techniques. The relation extraction process also creates a term taxonomy in the form of a sense hierarchy inferred from WordNet. Then, a novel generalized association pattern mining algorithm (GP-Close) is applied …

Percussive Penetration Of Unconsolidated Granular Media In A Laboratory Setting, Leslie S. Gertsch

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

This controlled study examined the feasibility of a simple percussive approach to drilling through unconsolidated regolith deposits on Mars. The experiments showed that the approach is feasible at the low power levels and low confining pressures used, and that the rate of impact is more important to the penetration rate than is the mass of the impactor (hammer). More massive impactors tend to lower energy efficiency, as they do in terrestrial pile-driving. Unexpectedly, penetration plotted against applied energy tends to cluster into parallel linear trends. Within a given cluster, penetration is very sensitive to applied energy, while between clusters, the …

Quality Of Service Routing Strategy Using Supervised Genetic Algorithm, Zhaoxia Wang, Yugeng Sun, Zhiyong Wang, Huayu Shen

Research Collection School Of Computing and Information Systems

A supervised genetic algorithm (SGA) is proposed to solve the quality of service (QoS) routing problems in computer networks. The supervised rules of intelligent concept are introduced into genetic algorithms (GAs) to solve the constraint optimization problem. One of the main characteristics of SGA is its searching space can be limited in feasible regions rather than infeasible regions. The superiority of SGA to other GAs lies in that some supervised search rules in which the information comes from the problems are incorporated into SGA. The simulation results show that SGA improves the ability of searching an optimum solution and accelerates …

Nevada Risk Assessment/Management Program (Nramp) – Phase 2: Quarterly Progress Report, Oct. 1, 2006- Dec. 31, 2006, Klaus J. Stetzenbach

Nevada Risk Assessment/Management Program

Work conducted in this initial period consisted of work start-up (technical, administrative, contractual), and interviewing/site visits with DOE NVO staff (and support contractors) and HRC staff to quickly ascertain current technical activities and priorities as related to the scope of this task.

Since much of the technical work scope builds on previous technical work, it was considered critical to determine the changes (programmatic, technical, and regulatory) that have occurred over the past several years that directly relate to the scope. It was also equally important to determine the technical and programmatic priorities that have been established in the interim.