Engineering Commons^™

A Symmetric Green Function For The Non-Collinear Magnetic Multilayer, Mikhail Ye Zhuravlev, John D. Burton, A. V. Vedyayev, Evgeny Y. Tsymbal

Materials Research Science and Engineering Center: Faculty Publications

Symmetry properties of the Green function in magnetic multilayers with noncollinear magnetization of the layers are investigated on the basis of the transfer matrix method. The Green function symmetric with respect to permutation of its arguments is constructed. It is shown how the boundary conditions can be imposed on this Green function.

We have proposed a constructive way to build a symmetric one-electron GF for the magnetic multilayer with magnetization in the plane of the layers. To build this GF we solved the following problems: finding the solution of the systems of differential equations of general form; matching the solutions …

The Wettability Of Titanium Diboride By Molten Aluminum Drops, D. A. Weirauch, W. J. Krafick, G. Ackart, P. D. Ownby

Materials Science and Engineering Faculty Research & Creative Works

Titanium diboride is widely accepted to be completely wet by liquid aluminum, yet few published wetting studies demonstrate this behavior, and reported contact angles vary widely. Sessile drop substrates from four different sources were selected and their microstructures and chemistries characterized. the results of sessile drop experiments using four techniques to modify oxide film behavior were compared. the Al-TiB2 interfaces were examined in metallographic sections or after chemical removal of the Al drop. Al wets a material containing 5.5 wt% Ni in vacuum experiments before the hold temperature of 1025°C is reached. the other TiB2 substrates are completely wet by …

Applying Particle Swarm Optimization To Dynamic Lot Sizing With Batch Ordering, Ahmad Hassan Sayed Aly

Archived Theses and Dissertations

No abstract provided.

Synthesis And Solution Characterization Of Water-Soluble Polyacrylamide And Its Applications In Oil Industries, Ghuwaya Humaid Alnuaimi

Theses

No abstract provided.

Instrumentation Of Ysz Oxygen Sensor Calibration In Liquid Lead-Bismuth Eutectic, X. Wu, Jian Ma, Yingtao Jiang, B. Fu, W. Hang, J. Zhang, N. Li

Mechanical Engineering Faculty Research

Liquid lead-bismuth eutectic (LBE), a good candidate for the coolant in the subcritical transmutation blanket, is known to be very corrosive to the stainless steel that transports it. Such a corrosion problem can be prevented by producing and maintaining a protective oxide layer on the exposed surface of the stainless steel. Proper formation of the oxide layer critically depends on the accurate measurement and control of the oxygen concentration in liquid LBE. An oxygen sensor calibration/measurement apparatus has been designed and built to deliberately calibrate an yttria stabilized zirconia (YSZ) oxygen sensor. A detailed description of this system with its …

Nonlinear Model For Reinforced Concrete Under Cyclic Loading, Aly Said, M. Elmorsi, M. Nehdi

Civil and Environmental Engineering and Construction Faculty Research

Most of the available shear models for reinforced concrete rely on empirical formulations. In this study, a rational shear stress function is used to define the shear stress–strain envelope for reinforced concrete. Cyclic rules are proposed to define the loading, unloading and reloading relationships for reinforced concrete under shear stress reversals. A normal stress function describing the cyclic relationship of concrete under axial stress is also introduced. The proposed functions are verified using experimental data of reinforced concrete panels tested under monotonic and cyclic loading. Subsequently, the normal and shear stress functions along with their cyclic rules are integrated in …

High-Temperature Monitoring Of Refractory Wall Recession Using Frequency-Modulated Continuous-Wave (Fm-Cw) Radar Techniques, Bivin Varghese, C. Deconick, G. Cartee, M. Velez, Robert E. Moore, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

Furnaces are among the most crucial components in the glass and metallurgical industry. Nowadays, furnaces are being operated at higher temperatures and for longer periods of time thus increasing the rate of wear on the furnace refractory lining. Consequently, there is a great need for a nondestructive tool that can accurately measure refractory wall thickness at high temperatures. In this paper the utility of a frequency-modulated continuous-wave (FM-CW) radar is investigated for this purpose.

Slip Behavior In Liquid Films On Surfaces Of Patterned Wettability: Comparison Between Continuum And Molecular Dynamics Simulations, Nikolai V. Priezjev, Anton A. Darhuber, Sandra M. Troian

Mechanical and Materials Engineering Faculty Publications

We investigate the behavior of the slip length in Newtonian liquids subject to planar shear bounded by substrates with mixed boundary conditions. The upper wall, consisting of a homogenous surface of finite or vanishing slip, moves at a constant speed parallel to a lower stationary wall, whose surface is patterned with an array of stripes representing alternating regions of no shear and finite or no slip. Velocity fields and effective slip lengths are computed both from molecular dynamics (MD) simulations and solution of the Stokes equation for flow configurations either parallel or perpendicular to the stripes. Excellent agreement between the …

Use Of Positron Annihilation Spectroscopy For Stress-Strain Measurements: Quarterly Progress Report (December 01, 2004 – February 28, 2005), Ajit K. Roy

Transmutation Sciences Materials (TRP)

The purpose of this collaborative research project involving the University of Nevada Las Vegas (UNLV), the Idaho State University (ISU), and the Los Alamos National Laboratory (LANL) is to evaluate the feasibility of determining residual stresses in cold-worked, plastically-deformed (bent), and welded materials using a nondestructive method based on positron annihilation spectroscopy (PAS). This technique uses γ-rays from a small MeV electron Linac to generate positrons inside the sample via pair production. This method is known to have capabilities of characterizing defects in thick specimens that could not be accomplished by conventional positron technique or other nondestructive methods. The data …

Effect Of Silicon Content On The Corrosion Resistance And Radiation-Induced Embrittlement Of Materials For Advanced Heavy Liquid Metal Nuclear Systems: Quarterly Progress Report (November 2004 – January 2005), Ajit K. Roy

Transmutation Sciences Materials (TRP)

This proposal is intended to study the effect of Si content not only on the corrosion resistance but also on the radiation-induced embrittlement of martensitic stainless steels. The susceptibility of these alloys with different Si content to stress corrosion cracking, general corrosion and localized corrosion will be evaluated in the molten LBE and aqueous environments of different pH values using state-of-the-art testing techniques. Testing in the aqueous media is intended to develop baseline data for comparison purpose. Radiation-induced embrittlement of these alloys will initially be studied by irradiating the test specimens with bremmstrahlung gamma radiation from 20-40 MeV electron beams …

Thermochemistry Of La 1-Sr Xfeo 3-Δ Solid Solutions (0.0 ≤ X ≤ 1.0, 0.0 ≤ Δ ≤ 0.5), Jihong Cheng, Alexandra Navrotsky, Xiao Dong Zhou, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

A series of compounds with the general formula La_1-xSr_xFeO_3-δ have been synthesized in the complete solid solution range 0.0 ≤ x ≤ 1.0 and 0.0 ≤ δ ≤ 0.5 with a variety of heat treatments. High temperature drops solution calorimetry in molten 2PbO·B₂O₃ at 702 °C was performed to determine their enthalpies of formation from oxides at room temperature. the enthalpy of oxidation involved in the reaction 2Fe^X_Fe + V _O^•• + 0.5O 2(g) = 2Fe _Fe^• + O _O^X is independent of oxygen nonstoichiometry in each …

An Exafs Investigation Of Rare-Earth Local Environment In Ultraphosphate Glasses, M. Karabulut, E. Metwalli, A. K. Wittenauer, Richard K. Brow, G. K. Marasinghe, C. H. Booth, J. J. Bucher, D. K. Shuh

Materials Science and Engineering Faculty Research & Creative Works

The local structures around rare-earth ions in rare-earth ultra phosphate glasses (nominally 15RE₂O₃-85P₂O₅, mol%, RE = Nd, Sm, Gd, Ho, and Er) and metaphosphate glasses (nominally 25RE₂O₃-75P₂O₅, mol%, RE = Nd, Gd, and Er) have been studied by extended X-ray absorption fine structure spectroscopy (EXAFS) at the respective rare-earth LIII edges. the RE-O distance decreases with increasing atomic number of the rare-earth ion for both ultra and metaphosphate glasses. on average, RE-O distances for metaphosphate glasses are shorter than those for ultra phosphate glasses …

Modeling, Fabrication, And Optimization Of Niobium Cavities: Phase Iii Fourth Quarterly Report, Robert A. Schill Jr., Mohamed Trabia, William Culbreth

Transmutation Sciences Materials (TRP)

Niobium cavities are important parts of the integrated NC/SC high-power linacs. Over the years, researchers in several countries have tested various cavity shapes. They concluded that elliptically shaped cells are the most appropriate shape for niobium superconducting cavities. The surface preparation can significantly affect the secondary electron emission yields. Such yields are used in design codes. Current codes use values obtained from niobium samples cleaned by a different means at temperatures other than the operating temperature. Secondary electron emission studies on LANL surface-cleaned niobium are conducted with preliminary data presented in this report at room temperature. Soon studies will be …

Sub-Surface Corrosion Research On Rock Bolt System, Perforated Ss Sheets And Steel Sets For The Yucca Mountain Repository — Quarterly Technical Report No. 3, Dhanesh Chandra, Jaak J.K. Daemen

Publications (YM)

This report encompasses the work done for third quarter in accordance to cooperative agreement of UCCSN for the Task 019 “Subsurface Corrosion Research on Rock Bolt System, Perforated SS Sheets and Steel Sets for the Yucca Mountain Repository”, the objective of which was proposed earlier, to conduct corrosion research and predict the durability of rockbolts and other underground metallic roof supports. We have recently started working on oxidation tests using Thermogravimetric Analyzer (TGA), stress corrosion cracking/hydrogen embrittlement studies on rock bolts, other support materials including bench mark materials. In this quarterly report we will discuss “Dry” oxidation of steels and …

Catalytic Conversion Of Hydrocarbons To Hydrogen And High-Value Carbon, Naresh Shah, Devadas Panjala, Gerald P. Huffman

Chemical and Materials Engineering Faculty Patents

The present invention provides novel catalysts for accomplishing catalytic decomposition of undiluted light hydrocarbons to a hydrogen product, and methods for preparing such catalysts. In one aspect, a method is provided for preparing a catalyst by admixing an aqueous solution of an iron salt, at least one additional catalyst metal salt, and a suitable oxide substrate support, and precipitating metal oxyhydroxides onto the substrate support. An incipient wetness method, comprising addition of aqueous solutions of metal salts to a dry oxide substrate support, extruding the resulting paste to pellet form, and calcining the pellets in air is also discloses. In …

Fabrication And Composition Control Of Niti Shape Memory Thin Films For Microactuators, Richard N. Savage, David J. Getchel

Materials Engineering

Microactuators fabricated with NiTi thin films take advantage of this material’s large energy density (~5-10 joules/cm3) and high strain recovery (~8%). Microelectromechanical Systems (MEMS) devices designed with these actuators can serve as biosensors, micro-fluidic pumps or optical switches. However, the fundamental mechanical properties stemming from the crystalline structure of these shape memory NiTi films have not been fully characterized with MEMS scale test structures. Understanding the relationship of crystalline structure, film stoichiometry, and phase transformation temperatures is crucial when designing a MEMS actuator. In addition, force displacement curves for both the martensite and austenite phases of NiTi are necessary to …

Ballistic Anisotropic Magnetoresistance, Julian P. Velev, Renat F. Sabirianov, Sitaram Jaswal, Evgeny Y. Tsymbal

Materials Research Science and Engineering Center: Faculty Publications

Electronic transport in ferromagnetic ballistic conductors is predicted to exhibit ballistic anisotropic magnetoresistance—a change in the ballistic conductance with the direction of magnetization. This phenomenon originates from the effect of the spin-orbit interaction on the electronic band structure which leads to a change in the number of bands crossing the Fermi energy when the magnetization direction changes. We illustrate the significance of this phenomenon by performing ab initio calculations of the ballistic conductance in ferromagnetic Ni and Fe nanowires which display a sizable ballistic anisotropic magnetoresistance when magnetization changes direction from parallel to perpendicular to the wire axis.

3d Modelling With Linear Approaches Using Geometric Primitives, Mochammad Zuliansyah

Makara Journal of Technology

In this paper, we study linear approaches for 3D model acquisition from non-calibrated images. First, the intrinsic and extrinsic camera calibration is taken into consideration. In particular, we study the use of a specific calibration primitive: the parallelepiped. Parallelepipeds are frequently present in man-made environments and naturally encode the affine structure of the scene. Any information about their euclidean structure (angles or ratios of edge lengths), possibly combined with information about camera parameters is useful to obtain the euclidean reconstruction. We propose an elegant formalism to incorporate such information, in which camera parameters are dual to parallelepiped parameters, i.e. any …

Tensile Properties Of Martensitic Stainless Steels At Elevated Temperatures, Ajit K. Roy, Srinivasarao R. Kukatla, Bhagath Yarlagadda, V. N. Potluri, Martin Lewis, Brendan O'Toole

Mechanical Engineering Faculty Research

Tensile properties of quenched and tempered martensitic alloys EP-823, HT-9, and 422 were evaluated at temperatures ranging from ambient to 600 °C as a function of three different tempering times. The results indicated that the yield strength, ultimate tensile strength, and the failure strength were gradually reduced with increasing temperature. The ductility parameters were enhanced at elevated temperatures due to increased plastic flow. However, the tempering time did not significantly influence these properties. The evaluation of the fracture surfaces by scanning electron microscopy revealed reduced cracking and dimpled microstructures, indicating enhanced ductility at higher testing temperatures.

Residual Stress Characterization In Structural Materials By Destructive And Nondestructive Techniques, Ajit K. Roy, Anand Venkatesh, Vikram Marthandam, Satish Dronavalli, Douglas P. Wells, Ronald Rogge

Mechanical Engineering Faculty Research

Transmutation of nuclear waste is currently being considered to transform long-lived isotopes to species with relatively short half-lives and reduced radioactivity through capture and decay of minor actinides and fission products. This process is intended for geologic disposal of spent nuclear fuels for shorter durations in the proposed Yucca Mountain repository. The molten lead-bismuth-eutectic will be used as a target and coolant during transmutation, which will be contained in a subsystem vessel made from materials such as austenitic (304L) and martensitic (EP-823 and HT-9) stainless steels. The structural materials used in this vessel will be subjected to welding operations and …

Fundamental And Applied Experimental Investigations Of Corrosion Of Steel By Lbe Under Controlled Conditions: Kinetics, Chemistry, Morphology, And Surface Preparation: Quarterly Report (January 2005-April 2005), Allen L. Johnson, John Farley, Dale L. Perry

Transmutation Sciences Materials (TRP)

This project has four components:

• The fabrication of a materials test apparatus with unique capabilities,
• Comparative studies of steel corrosion under gas phase conditions comparable to the Lead Bismuth Eutectic (LBE) oxygen control conditions,
• Isotope labeling studies, and
• Collaborative efforts with other workers in the field.

Summary of accomplishments:

• Started occupation of the High Temperature Materials Experimental Facility.
• Presented a paper at the meeting of the American Chemical Society in San Diego in March 13-17.
• Currently reviving the ion beam for implantation experiments.
• Currently analyzing 38 steel samples from the DELTA loop from LANL.

Synthesis Dibenzyl Terephthalate Through Depolimerization Of Poly (Ethylene Terephthalate) As Alternative Of Waste Plastics Recycling, Suwardi Suwardi, Crys Fajar Partana, Agus Salim, Dyah Anitasari

Makara Journal of Technology

Synthesis Dibenzyl Terephthalate Through Depolimerization of Poly(ethylene terephthalate) as Alternative of Waste Plastics Recycling. Synthesis dibenzyl terephathalate were done through PET degradation by refluxing in benzyl alcohol at 145oC temperature for 20, 24, and 28 hours in the presence of zinc acetate catalyst. The result of degradation was purified by recristalization in methanol and then melting point (mp), FTIR, 1H NMR spectra, and TLC spot were determined. The melting point of product degradation for 28 hours was 98-99 oC. Based FTIR spectra known that compunds of product degradation have OH, C=O, C-O, CH, monosubstituted benzene, disubstituted benzene groups, while on …

Dipole Magnetization Effect To Kerosene Characteristics, Mochamad Chalid, Nelson Saksono, Adiwar Adiwar, Nono Darsono

Makara Journal of Technology

Dipole Magnetization Effect to Kerosene Characteristics. Investigation of kerosene characteristics has been done by ex-situ dipole magnetization. The results show that magnetization technique can be able to influence kerosene characteristics. Polarity and viscosity of the kerosene are observed by measuring refractive index and viscosity. An hour of 4330 Gauss flux magnetic will increase refractive index from 1.447 to 1.449 and decrease the viscosity from 1.278 to 1.256. Those changing support de-clustering occurrence and polarity increment of kerosene molecule. Gas chromatography and infrared result show that those changing do not alter kerosene structure and composition.

Study Of 2d And 3d Optical Beam Induced Voltage Imaging Using Photoresistor Sensor, Warsito Warsito, Sri Wahyu Suciyati, Susi Harnani, Akhmad Dzakwan

Makara Journal of Technology

Study of 2D and 3D Optical Beam Induced Voltage Imaging Using Photoresistor Sensor. This article shows a method to study OBIV (optical beam induced voltage) imagerie system, that usually employ a laser scanning microscopy system. The OBIV imagerie system developed use a photoresistor sensor as a sample and simultaneously it can be used for analyzing its inhomogeneity response. Resolution of the system is still low, about 350μm due to high value of incident light diameter. The results inform that photoresistor sensors gave an optimum response if the incident light hits the center of sensible zone.

Flexi Radio Base Station (Rbs) Performance Analysis Of Voice And Trafic On Kota 2 Jakarta Barat Base Station Control (Bsc), Mushfar Ferdian, Fitri Yuli Zulkifli

Makara Journal of Technology

Flexi Radio Base Station (RBS) Performance Analysis of Voice and Trafic on Kota 2 Jakarta Barat Base Station Control (BSC). The CDMA 2000 technology uses circuit switch method to handle voice traffic and packet switch method to handle data traffic between the user and RBS (Radio Base Station). These two parameters can be used to measure performance of the network generally, so it is necessary to optimize them. This paper analyze the performance of RBS by measuring its parameters such as set up failure ratio, drop ratio, and occupancy. Furthermore, the traffic increment is calculated too in order to provide …

Water Quality Of Rivers And Ponds On Dki Jakarta, Diana Hendrawan

Makara Journal of Technology

Water Quality of Rivers and Ponds on DKI Jakarta. Thirteen big rivers, some small rivers, and 40 ponds spread over districts at Jakarta city are potential to support human being life. As the population is growing and the usage of stream water is increasing, the condition and quality of rivers and ponds are changing. Crowd housing can affect rivers and ponds pollution, as the people awareness about clean and healthy environment is less. Stream water pollution assessment can be done by counting the effect of pollutant to life of stream water organisms. This assessment unit could be classified into physics, …

Time Domain Characterization Of 1-2 Ghz Circular-Ended Bowtie Antenna Using Normalizad Impulse Response, Joko Suryana, Andriyan B. Suksmono, Tati R. Mengko

Makara Journal of Technology

Time Domain Characterization of 1-2 GHz Circular-ended Bowtie Antenna Using Normalizad Impulse Response. Frequency domain analysis is a powerful and compact tool for characterizing the antenna parameters such as gain, radiation pattern and the impedance as a function of frequency. However, if time or space is a major concern, such as in the GPR appication, the time domain analysis would be a very important tool due to their unique capability for determining the echo delay and range profile of target image. In this paper, we will describe the classical theory of system characterization in time domain, and then also propose …

Carbon Nanotubes And Tungsten Oxide Nanorods: Synthesis And Applications, Bing Xiao

Electrical & Computer Engineering Theses & Dissertations

Synthesis and applications of two types of one-dimensional nanomaterials, carbon nanotubes (CNTs) and tungsten oxide nanorods, are investigated in this dissertation. Multi-walled CNTs have been successfully synthesized using two types of chemical vapor deposition (CVD) methods: microwave plasma enhanced CVD and atmospheric pressure thermal CVD. CNTs and their synthesis processes are characterized with various analysis techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and optical emission spectroscopy. Ultra-thin and high quality multi-walled CNTs are discovered in CNT films produced by MPCVD, which exhibit good field emission performance that is found to be dependent on the synthesis …

High Temperature Heat Exchanger Project:Quarterly Progress Report January 1, 2005 Through March 31, 2005, Anthony Hechanova

Publications (NSTD)

Quarterly Collaboration Meeting. Ceramatec, Inc. hosted a UNLVRF HTHX Project quarterly meeting on March 17 in Salt Lake City, Utah. The purpose of the meeting was to promote collaboration and communication among the UNLV Research Foundation partners. Collaborators had the opportunity to discuss their research program plan and update their progress. The next meeting will be in June in San Diego City hosted by General Atomics.

Theoretical Modeling Of Protective Oxide Layer Growth In Non-Isothermal Lead-Alloys Coolant Systems: Quarterly Progress Report (01/01/05- 03/31/05), Yitung Chen

Transmutation Sciences Materials (TRP)

The goal of the proposed research project is to provide basic understanding of the protective oxide layer behaviors and to develop oxide layer growth models of steels in non-isothermal lead-alloys (lead or lead-bismuth eutectic) coolant systems. It is widely recognized that the corrosiveness of the lead-alloys is a critical obstacle and challenge for which it can be safely used or applied in the nuclear coolant systems. Active oxygen control technique can promote the formation of the “self-healing” oxide films on the structural material surface, drastically reducing steel corrosion and coolant contamination. Many experiments of steels exposed to flowing lead-alloys have …