Engineering Commons^™

Rf-Sputter Fabrication Of Magnetic Garnet Thin Films And Simulation Modeling For 1-D Magnetic Photonic Crystal Waveguide Devices, Haichun Yang

Dissertations, Master's Theses and Master's Reports - Open

One dimensional magnetic photonic crystals (1D-MPC) are promising structures for integrated optical isolator applications. Rare earth substituted garnet thin films with proper Faraday rotation are required to fabricate planar 1D-MPCs. In this thesis, flat-top response 1D-MPC was proposed and spectral responses and Faraday rotation were modeled. Bismuth substituted iron garnet films were fabricated by RF magnetron sputtering and structures, compositions, birefringence and magnetooptical properties were studied. Double layer structures for single mode propagation were also fabricated by sputtering for the first time.

Multilayer stacks with multiple defects (phase shift) composed of Ce-YIG and GGG quarter-wave plates were simulated by the …

Electronic Commerce Negotiation In A Supply Chain Via Constraint Evaluation, R. Wilhelm, B. Chu, R. Sun

Department of Mechanical and Materials Engineering: Faculty Publications

Negotiation is of critical importance in e-commerce applications where the supply chain is dynamic and reconfiguring. In this research supply chain negotiation problems are addressed as constraint-satisfaction problems. In general each negotiation is handled in the largest scope possible to avoid the suboptimality that can result from many local solutions. This global approach, however, must be balanced with time constraints that apply in e-commerce supply chain execution. In this paper, we describe a new approach for e-commerce supply chain negotiation via constraint evaluation. As well, results from prototype software, distributed across the internet, are discussed. Beyond the general formulation, we …

Managing The Transformation Of System Of Systems Engineering, Samuel F. Kovacic, Andres Sousa-Poza

Engineering Management & Systems Engineering Faculty Publications

SOSE methodologies exist that support engineering difficult and disparate systems with a technical solution. However, from literature it is apparent that there is a need for a formal methodology and methods that govern engineering of System of Systems (SOS) beyond the technical solution. This paper presents some of the current thinking being undertaken at NCSOSE (National Centers for Systems of Systems Engineering), on what is driving the development of SOSE, and a hypothesized solution to this problem. The purpose is to offer a different approach for resolving complexity within a situation. The paper concludes with an initial derivative of a …

Adaptive Voip Playout Scheduling: Assessing User Satisfaction, Miroslaw Narbutt, Andrew Kelly, Liam Murphy, Philip Perry

Articles

Delay and packet loss dramatically affect the quality of a voice-over-IP (VoIP) call and depend on the playout buffer scheme implemented at the receiver. The choice of playout algorithm can’t be based on statistical metrics without considering the perceived end-to-end conversational speech quality. The authors present a method for evaluating various playout algorithms that extends the Emodel concept by estimating user satisfaction from time-varying transmission impairments. This article evaluates several playout algorithms and shows a correspondence between their results and those obtained via statistical loss and delay metrics.

Supercritical Fluid Extraction Of Rice Bran With Adsorption On Rice Hull Ash, Paresh Manilal Patel

LSU Doctoral Dissertations

Rice bran oil was extracted using environmentally-friendly supercritical carbon dioxide at varying conditions. Experimental treatments included pressure (27.6, 41.4 and 55.2 MPa), temperature (40 and 60 oC) and flow rates (25, 45 and 65 g/min) of supercritical carbon dioxide. Extracts collected at different time intervals during 4-hour extraction runs in a 3-L extractor were analyzed for oil yield and antioxidants. Normal-phase HPLC was used for analyzing the extract for important antioxidant compounds of oryzanol, tocopherols, tocotrienols. Silica rich rice hull ash adsorbent was also incorporated in combined extraction-adsorption experiments under similar supercritical fluid conditions. Supercritical extraction yields of rice bran …

Evidence Of Neotectonic Activity In Southwest Louisiana, Jordan Oliver Heltz

LSU Master's Theses

A methodology that combines high-resolution topographic mapping, field observations, subsurface evaluation, and geodetic data analysis has successfully located several fault-related geomorphic steps in an area of southwestern Louisiana once thought to be relatively devoid of such features. Comparison of height differences of benchmarks straddling these suspected fault-related steps shows that vertical displacement rates on faults in the study area ranged from about 2 mm/yr to as much as 6 mm/yr during the 1960’s and 1970’s. However, leveling data obtained as recently as January 2005 reveals that the majority of these faults are currently moving at rates of less than 1 …

A Project Improvement System For Effective Management Of Construction Projects, Shahriyar Mojahed

LSU Doctoral Dissertations

The concept of construction productivity began in the early 20th century with a series of time and motion studies to improve bricklaying operations. A substantial number of subsequent studies focused on repetitive tasks and automation of the manufacturing operations and subsequently benefited manufacturing more than the construction industry. There has been a lack of studies for productivity improvement in the construction industry. Building upon the available body of knowledge as it related to productivity of manufacturing and construction industries, this study focused on developing a project improvement system for effective management of construction projects. Development of the system included a …

Transport And Kinetics Of Aromatic Hydrocarbons Into Micron-Sized Liquid Droplets: With Applications To Atmospheric Chemistry, Suresh Raja

LSU Doctoral Dissertations

In the natural process of wet deposition, gas-water interfaces play an important role in the transport of chemical contaminants in the atmosphere via fog, rain and cloud drops. Evidences from several other works point out deviations in gas-liquid partitioning as predicted by Henry’s law. Uptake and mass transfer of benzene, naphthalene, and phenanthrene was chosen to study in a falling droplet train apparatus. Higher droplet-to-vapor partition constant (KDV) was noted for diameters less than 200ìm and was attributed to surface adsorption and accumulation. Mass transfer of phenanthrene was dependent on gas-phase diffusion and mass accommodation at the interface, while the …

A Tablet Pc Application For Construction Site Safety Inspection And Fatality Prevention, Prabhu Sunkara

LSU Master's Theses

Construction industry accounts for the largest number of occupational injuries and fatalities every year. Occupational Safety and Health Administration (OSHA) is an organization responsible for regulating and enforcing standards for various occupations to ensure safe working conditions including construction industry. As an OSHA requirement, every construction employer should employ a safety program that involves both training of the employees and frequent site inspections. OSHA has provided an online ‘construction eTool’ as a training tool which also aids in the development of safety inspection procedures. Traditionally, safety inspections are paper based and usually designed to address a specific work area or …

Purification And Structural Characterization Of Caged Dna Oligonucleotides, Brendan Michael Mcadams

LSU Master's Theses

“Cage” molecules reversibly block the bioactivity of a target substrate molecule by a photolyzable covalent bond formed at a functional site of the target molecule. The attachment of cage molecules to DNA oligodeoxynucleotides (ODNs) to transiently block bioactivity, and site-specific restoration of bioactivity using targeted light exposure, would enable a new method of control for use in gene therapy, molecular/DNA computing, molecular biology, and drug delivery. The reaction of the cage molecule 1-(4,5-dimethoxy-2-nitrophenyl)diazoethane (DMNPE) with DNA ODNs in an batch reaction yields a mixture of products with varying degrees of caging. Purification and verification of the hypothesized site of DMNPE …

The Electrodeposition And Property Study Of Nickel-Rhenium Alloy, Shirong Wen

LSU Master's Theses

The electrodeposition of nickel-rhenium alloys from Ni(II) and Re(VII) solution was studies in an aqueous acidic solution. Different plating current density and pH have been carried out, and the effect of them on the composition of the deposited Ni-Re alloy was studied. Wavelength-dispersive spectrometer (WDS) was used to measure the composition of Ni-Re alloy. The thermal stability of nickel-rhenium alloy system has been investigated. Differential scanning calorimetry (DSC) tests have been conducted for the electroplated Ni-Re samples in order to find the possible heating initiated interactions at elevated temperatures. To investigate the thermal stability of Ni-Re alloys, the samples were …

Development Of High Performance Hybrid Syntactic Foams: Structure And Material Property Characterization, Rahul R. Maharsia

LSU Doctoral Dissertations

Syntactic foams are light weight particulate composites that use hollow particles (microballoons) as reinforcement in a polymer resin matrix. High strength microballoons provide closed cell porosity which helps in reducing weight of the material. Due to their wide range of possible applications such as in aerospace and marine structures, it is desirable to modify the physical and mechanical properties of syntactic foams as per the requirements of an application. Various filler materials can be used to modify the foam microstructure to attain these desired properties. Compression tests have revealed that high density syntactic foams demonstrate poor damage tolerance and low …

Managing The Transformation Of System Of Systems Engineering, Samuel F. Kovacic, Andres Sousa-Poza

Engineering Management & Systems Engineering Faculty Publications

SOSE methodologies exist that support engineering difficult and disparate systems with a technical solution. However, from literature it is apparent that there is a need for a formal methodology and methods that govern engineering of System of Systems (SOS) beyond the technical solution. This paper presents some of the current thinking being undertaken at NCSOSE (National Centers for Systems of Systems Engineering), on what is driving the development of SOSE, and a hypothesized solution to this problem. The purpose is to offer a different approach for resolving complexity within a situation. The paper concludes with an initial derivative of a …

Influence Of Composition And Heat-Treatment On The Charge Transport Properties Of Poly(3-Hexylthiophene) And [6,6]-Phenyl C61-Butyric Acid Methyl Ester Blends, Jinsong Huang, Gang Li, Yang Yang

Department of Mechanical and Materials Engineering: Faculty Publications

Poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C₆₁-butyric acid methyl ester (PCBM) blends have been demonstrated to form highly efficient polymer photovoltaic devices. In this letter, the time-of-flight technique is used to investigate the influence of composition and heat treatment on charge transport properties of P3HT and PCBM blends. The transport of electrons and holes both display a transition from dispersive to nondispersive and return to dispersive again as the percentage of PCBM increases. A balanced mobility of both electron and hole is obtained at a composition of 1:1 weight ratio, and it is nearly independent of the electrical field in …

Effect Of Microstructure And Alloying Elements On The Resistance Of Fastener Grade Steels To Hydrogen Assisted Cracking , Nicholas E. Nanninga

Dissertations, Master's Theses and Master's Reports - Open

Fastener grade steels with varying alloy contents and heat treatments were employed to measure changes in resistance to hydrogen assisted cracking. The testing procedure compared notched tension specimens fractured in air to threshold stress values obtained during hydrogen charging, utilizing a rising step load procedure. Bainitic structures improved resistance by 10-20% compared to tempered martensite structures. Dual phase steels with a tempered martensite matrix and 20% ferrite were more susceptible and notch sensitive. High strength, fully pearlitic structures showed an improvement in resistance. Carbon content, per se, had no effect on the resistance of steel to hydrogen assisted cracking. Chromium …

Sub-Surface Corrosion Research On Rock Bolt System, Perforated Ss Sheets And Steel Sets For The Yucca Mountain Repository, Dhanesh Chandra, Jaak J.K. Daemen, Jaime Gonzalez, Raymond Keeler, Amy J. Smiecinski

Publications (YM)

The objective of the proposed investigation is to conduct corrosion research and predict the durability of rock-bolts and other underground metallic roof supports. In critical areas, it is possible to use highly corrosion resistant steels for rock bolts at Yucca Mountain (YM) repository, as the steel rock bolts, as well as other materials such as Bernold type shields for tunnels at YM site [1-4]. In addition, there is propensity for stress corrosion cracking as well as hydrogen induced cracking in rock bolts likely to occur in YM repository emplacement under drift conditions. As corrosion of these materials for underground support …

Oxidation Of Titanium In Alpha-Calf Serum Solution, Ali Stait Ismailoglu

Masters Theses

Titanium and its alloys have been used extensively in orthopedic implants mainly because of its excellent biocompatibility. This biocompatibility is attributed to its surface oxide film (3-7 nm thickness) that forms immediately upon exposure of titanium to air. In the research, the oxidation of Ti-6Al-4V in alpha-calf serum solution was studied. Four different immersion times were tested. Characterization of surface topography and its chemical composition was examined using Atomic force microscopy (AFM), Fourier transform-infrared radiation (FT-IR), and X-ray photoelectron spectroscopy (XPS). The AFM results clearly show the gradual change that occurred in the samples topography which is associated with more-rounded …

Stress Corrosion Cracking Resistance Of Martensitic Stainless Steels For Transmutation Applications, Phani P. Gudipati

UNLV Theses, Dissertations, Professional Papers, and Capstones

The susceptibility of Alloy EP-823 to stress corrosion cracking has been evaluated using smooth and notched cylindrical specimens in neutral and acidic solutions at ambient and elevated temperatures using constant load and slow strain rate testing (SSR) techniques. C-ring and U-bend specimens have also been tested in the acidic solution. The effect of hydrogen on the cracking susceptibility has been evaluated under controlled cathodic potential. While no failures were observed with smooth specimens at constant load, the notched specimens showed failure. The SSR test results indicate that the true failure stress (o'_f), time to failure and ductility parameters …

Stress Corrosion Cracking And Hydrogen Embrittlement Of Martensitic Alloy Ep-823, Mohammad K. Hossain

UNLV Theses, Dissertations, Professional Papers, and Capstones

This investigation is focused on the evaluation of stress corrosion cracking (SCC), localized corrosion, and hydrogen embrittlement (HE) susceptibility of martensitic Alloy EP-823 in neutral and acidic solutions at ambient and elevated temperatures. While no failures were observed in smooth specimens in the neutral solution, failures were noticed in the 90°C acidic solution at constant-load (CL) leading to a threshold stress (O'_th) of 102 ksi. The presence of a notch reduced the O'_th value to 91 ksi in a similar environment. The ductility (%El and %RA), time-to-failure (TTF), and true failure stress (O'_r) were gradually …

Cfd Analysis Of 3-D Thermalhydraulics Flow Effects On Wall Concentration Gradient Profiles For Lbe Loop Fittings, Narain Armbya

UNLV Theses, Dissertations, Professional Papers, and Capstones

The objective of the thesis is to study the effects of thermalhydraulics flows on the wall concentration gradient profiles in LBE loop fittings. To that end detailed models of the fittings have been constructed to study these effects. These fittings include sudden expansion, sudden contraction, t-joint and elbow. The typical flow rates chosen for these simulations are typical of design criteria chosen for the loop with Reynolds numbers expected around 200,000 and the usual axial temperature profiles which are being characterized in the DELTA loop at LANL. STAR-CD is the simulation package used to make these predictions, which include detailed …

Studies On The Electrochemical Preparation And Electrochemical Properties Of Conducting Polymers——Brief Introduction To The Research Work Of Electrochemistry Of Conducting Polymers In Cas Key Laboratory Of Organic Solids(I), Yong-Fang Li

Journal of Electrochemistry

Conducting polymers have drawn much attention since the discovery of conducting polyacetylene in 1977, due to the novelty and curiosity of their structure and properties as well as their promising applications in many aspects. Among the studies of conducting polymers, the electrochemical preparation and electrochemical properties of conducting polymers are of special importance, because the electropolymerization is a main method for preparing conducting polymer films and the electrochemical properties are the basis for their applications in the fields of electrode materials for batteries, electrocatalysis, electrochromic display, etc. We are one of the earliest research groups in the world to perform …

Preparation And Photo-Catalyst Properties Of The α-Fe2O3-Tio2 Films On Sodium Alginate Polymer, Li-Qin Chen, Huai-Zhen Zhong, Ri-Yao Chen, Xi Zheng, Zhen Chen

Journal of Electrochemistry

Three new nano thin films of α-Fe₂O_3, TiO₂ and α-Fe₂O₃-TiO₂ by doping their powder with sodium alginate polymer were prepared. Surface structure and catalytic activities of the films were characterized by FTIR, XRD, PL, TEM and I-V techniques. The results of UV-visible absorption showed that the methylene blue was mineralized in aqueous of α-Fe₂O₃/SA, TiO₂/SA and (α-(Fe₂O₃))-TiO₂ /SA upon radiation with ultra violet light. α-Fe₂O₃ enhanced their photo-decolorized-activities by doping 15% TiO₂.

Electrochemical Behaviours Of Hemoglobin-Ddab-Modified Powder Microelectrode And The Application Of The Powder Microelectrode In Determination Of Nitric Oxide, Zhi-Mou Guo, Huan Liu, Jian Chen, Wen-Ting Zhang

Journal of Electrochemistry

The electrochemical behaviours of DDAB-Hb-PME were studied in this paper. The (apparent) surface concentration of Hb was enhanced greatly by using the powder microelectrode (technique). NO reacts with Hb and absorbs on the surface of the modified carbon powder. Therefore, the output of the electrode was enhanced greatly by employing PME with higher reaction surface (area). The sensitivity of DDAB-Hb-PME is 3.1 mA/μmol·L^-1·cm², which is much larger than the values obtained with the traditional electrodes. The detection limit is 9 nmol·L^-1 and the linear response range is 9～100 nmol·L^-1.

Improvement And Its Mechanism Of Storage Performance Of Ni-Mh Battery, Xiao-Feng Li, Li-Ping Ma, Yu-Wan Lou, Feng Li, Bao-Jia Xia

Journal of Electrochemistry

The storage performance of nickel-metal-hydride (Ni-MH) battery was studied by using galvanostatic charge-discharge and cyclic voltammetry. The experimental results indicated that CoOOH could not be completely restored after its being thoroughly reduced at lower potential, which might weaken electric conduction network in the positive electrode and result in fading of electrochemical properties of Ni-MH battery. Addition of nickel powder as a conductive agent into the positive electrode was beneficial to the capacity recovery after storage.

Preparation And Electrochemical Magnesium Insertion Behaviors Of Mgv2O6, Hua-Tang Yuan, Li-Fang Jiao, Jian-Sheng Cao, Xiu-Sheng Liu, Ming Zhao, Yong-Mei Wang

Journal of Electrochemistry

MgV₂O₆ was synthesized by conventional solid-state reaction from MgO and V₂O₅ as starting materials. X-Ray diffraction analysis showed that the prepared sample belongs to the monoclinic structure. Electrochemical magnesium insertion from aprotic electrolytes such as organomagnesium halides into this host was found possible and exhibited charge/discharge circulation.

Study On Mass Transport In Liquid Layer Adjacent To The Electrode Through Transmission Vop-Spectroellipsometry, Wei Zhu, Yu-Ru Yang, Zong-Qing Huang

Journal of Electrochemistry

In electrochemical system, the mass transport process in liquid layer adjacent to electrode is studied through theoretical analysis only.The diffusion process can be analyzed theoretically by Fick's law for homogeneous media. Up to now, none of satisfied experimental method has been reported for studying mass transport of a whole process in liquid media yet. This paper described the experimental approach to explore mass transport in electrochemical system by transmission Vop-spectroellipsometry briefly.

Electrocatalytic Performances Of Carbon Nanotube Air Electrode For Oxygen Reduction, Feng-Ming Zhao, Chun-An Ma

Journal of Electrochemistry

The air electrodes with different mass ratio of Pt/active carbon or carbon nanotube as catalyst layer material have been prepared. The electrocatalytic performances for oxygen reduction were evaluated by means of polarization curve and electrochemical impedance spectroscopy (EIS). The results disclosed that carbon nanotubes dealt with nitric acid in the catalyst layer had been improved obviously on the electrocatalytic activity. After the surface of carbon nanotube was oxygenated and aggraded with platinum, the catalyst had obviously effects on the electrocatalytic activity. The air electrode with the mass ratio of active carbon to Pt/carbon nanotube in 4∶1 showed better electrocatalytic activity, …

The Investigation Of Bafesi/C Alloy Composite As Anode Materials For Li-Ion Battery, Rui-Xiang Feng, Hua Dong, Xin-Ping Ai, Han-Xi Yang

Journal of Electrochemistry

A novel BaFeSi/C composite was prepared by mechanical ball milling, and lithium insertion reactions on the composite electrode were investigated by cyclic voltammetry , charge-discharge measurements, XRD and XPS spectroscopy. It is demonstrated that the capacity retention with indiscernible capacity decas during charge-discharge cycling. The improved cycling ability of the composite is suggested from a cooperative action by inactive FeSi₂ and BaSi₂ matrix and outer graphite shell, which both buffer the volumetric changes of the active Si phase and provide a good connection for electronic and ionic conduction during lithium insertion and extraction processes.

Electrochemical Investigations On Pitting Susceptibility Of Iron-Based Alloy, Wei-Shan Li, Hong-Yu Chen, Zhong-Zhi Yuan, Hong Li, Qi-Ming Huang, Dong-Sheng Lv

Journal of Electrochemistry

The formation process of passive film on iron and electronic properties and pitting susceptibility of an iron-based alloy are investigated by using linear potential sweep, alternative current impedance and electrochemical nose technologies. The relationship between reciprocal square capacitance and potential following the Mott-Schottky behavior is limited at a narrow rang of low potentials. At higher potentials, linear relationship between reciprocal capacitance and potential is obtained, which is ascribed to the increasing thickness of the passive film with potential. The donor density of the passive film is influenced by the formation potential of the film, passivator and microstructure. The decrease in …

LicoXNi1-XO2 Cathode Materials Prepared By Electrolysis Of Co And Ni, Jin-Ping Wei, Xin Sun, Xiao-Yu Wang, Xi-Kui Bian, Jin-Ling Zhai, Yan-Jie Yan-Jie

Journal of Electrochemistry

A new electrolytic method was developed to prepare LiCo_xNi_1-xO₂ as a cathode material of lithium-ion battery. Contrary to the traditional method, electrolytic method is a potential method with simple process to industrialization and no pollution. Metal cobalt and nickel were electrolysed in parallel to prepare the precursor of Co_xNi_{1- x}(OH)₂.Different compositional precursors could be conveniently prepared by changing electrolytic current. The LiCo_0.3Ni_0.7O₂ cathode prepared by this method was found favorable charge-discharge and cycle properties. For the LiCo_0.3Ni_0.7O₂ cathode material, …