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Plating Thickness Tester

Description: An electromagnetic eddy current instrument is described that is capable of measuring copper and nickel plating 1 to 8 mils thick plated on bismuth mandrils of various sizes and shapes.
Date: November 15, 1957
Creator: Fitch, C. E., Jr.
Partner: UNT Libraries Government Documents Department


Description: Bridged crack models using beam theory formulation have proved to be effective in the modeling of quasistatic delamination crack growth in through thickness reinforced structures. In this paper, we model dynamic crack propagation in these structures with the beam theory formulation. Steady state crack propagation characteristics unique to the dynamic case are first identified. Dynamic crack propagation and the energetics of steady state dynamic crack growth for a Double Cantilever beam (DCB) configuration loaded with a flying wedge is examined next. We find that steady state crack growth is attainable for this loading configuration provided certain conditions are satisfied.
Date: February 1, 2001
Creator: SRIDHAR, N. & AL, ET
Partner: UNT Libraries Government Documents Department

Analysis of formulas used in coupling impedance coaxial-wire measurements for distributed impedances

Description: In this paper we study the validity of coupling impedance bench measurements for distributed impedances, comparing the commonly used log formula to the result obtained applying a modified version of Bethe's theory of diffraction to a long slot in a coaxial beam pipe. The equations found provide a quantitative expression for the influence of the wire thickness used in the measurement of the real and imaginary part of the longitudinal impedance. The precision achievable in an actual measurement is therefore discussed. The method presented has also been applied in the presence of lumped impedances [1].
Date: May 30, 2002
Creator: De Santis, Stefano
Partner: UNT Libraries Government Documents Department

Characterization of SEI layers on LiMn2O4 cathodes with in-situ spectroscopic ellipsometry

Description: In situ spectroscopic ellipsometry was employed to study the initial stage of SEI layer formation on thin-film LiMn{sub 2}O{sub 4} electrodes. It was found that the SEI layer formed immediately upon exposure of the electrode to EC/DMC (1:1 by vol) 1.0 M LiPF{sub 6} electrolyte. The SEI layer thickness then increased in proportion to a logarithmic function of elapsed time. In comparison, the SEI layer thickness on a cycled electrode increased in proportion to a linear function of the number of cycles.
Date: August 30, 2004
Creator: Lei, Jinglei; Li, Lingjie; Kostecki, Robert; Muller, Rolf & McLarnon, Frank
Partner: UNT Libraries Government Documents Department

Simulating Nonuniform Properties in Polymer-Electrolyte FuelCells

Description: In this transaction, results from mathematical, pseudo 2-D simulations are shown for four different thickness distributions of both the membrane and cathode catalyst layer. The results and subsequent analysis clearly demonstrate that the position along the gas channel is more important than the local thickness variations, especially for the membrane.
Date: July 1, 2006
Creator: Weber, A.Z. & Newman, J.
Partner: UNT Libraries Government Documents Department

A Graphical Big Picture for Tank Technologies

Description: A graphical method is presented for comparing different tank technologies and evaluating scalability, over wide ranges of volume and pressure. Mass contours are plotted on log-log graphs of pressure versus volume, using either theory or data points representing hardware. The simple theoretical case for infinitely scaleable tanks made of a single isotropic material has a constant value of PV/m over the entire plot, and results in straight diagonal mass contours. The contours become more complicated as a result of practical considerations. The latter include minimum wall thickness limits and non-pressure structural loads, as well as minimum thicknesses for the liner and composite over-wrap of multi-layered tank walls. Given a requirement for a tank at a particular volume and pressure, a set of plots representing different technologies can be used to estimate tank masses and select one or more technologies that would meet the need.
Date: June 15, 2007
Creator: Whitehead, J C
Partner: UNT Libraries Government Documents Department

A Top to Bottom Lithospheric Study of Africa and Arabia

Description: We study the lithospheric structure of Africa, Arabia and adjacent oceanic regions with fundamental-mode surface waves over a wide period range. Including short period group velocities allows us to examine shallower features than previous studies of the whole continent. In the process, we have developed a crustal thickness map of Africa. Main features include crustal thickness increases under the West African, Congo, and Kalahari cratons. We find crustal thinning under Mesozoic and Cenozoic rifts, including the Benue Trough, Red Sea, and East, Central, and West African rift systems. Crustal shear wave velocities are generally faster in oceanic regions and cratons, and slower in more recent crust and in active and formerly active orogenic regions. Deeper structure, related to the thickness of cratons and modern rifting, is generally consistent with previous work. Under cratons we find thick lithosphere and fast upper mantle velocities, while under rifts we find thinned lithosphere and slower upper mantle velocities. There are no consistent effects in areas classified as hotspots, indicating that there seem to be numerous origins for these features. Finally, it appears that the African Superswell has had a significantly different impact in the north and the south, indicating specifics of the feature (temperature, time of influence, etc.) to be dissimilar between the two regions. Factoring in other information, it is likely that the southern portion has been active in the past, but that shallow activity is currently limited to the northern portion of the superswell.
Date: October 31, 2006
Creator: Pasyanos, M
Partner: UNT Libraries Government Documents Department

Probing the evolution of antiferromagnetism in multiferroics

Description: This study delineates the evolution of magnetic order in epitaxial films of the room-temperature multiferroic BiFeO3 system. Using angle- and temperature-dependent dichroic measurements and spectromicroscopy, we have observed that the antiferromagnetic order in the model multiferroic BiFeO3 evolves systematically as a function of thickness and strain. Lattice-mismatch-induced strain is found to break the easy-plane magnetic symmetry of the bulk and leads to an easy axis of magnetization which can be controlled through strain. Understanding the evolution of magnetic structure and how to manipulate the magnetism in this model multiferroic has significant implications for utilization of such magnetoelectric materials in future applications.
Date: June 9, 2010
Creator: Holcomb, M.; Martin, L.; Scholl, A.; He, Q.; Yu, P.; Yang, C.-H. et al.
Partner: UNT Libraries Government Documents Department

Equivalent-Circuit Model for the TSM Resonator with a Viscoelastic Layer

Description: This paper describes a new equivalent-circuit model for the thickness shear mode resonator with a surface viscoelastic layer operating near film resonance. The electrical impedance of the film is represented by a simple three-element parallel circuit containing a resistor, a capacitor, and an inductor. These elements describe the film's viscous power dissipation, elastic energy storage, and kinetic energy storage, respectively. Resonator response comparisons between this lumped-element model and the general transmission-line model show good agreement over a range of film phase conditions and not just near film resonance.
Date: September 16, 1999
Partner: UNT Libraries Government Documents Department

Glue Film Thickness Measurements by Spectral Reflectance

Description: Spectral reflectance was used to determine the thickness of thin glue layers in a study of the effect of the glue on radiance and reflectance measurements of shocked-tin substrates attached to lithium fluoride windows. Measurements based on profilometry of the components were found to be inaccurate due to flatness variations and deformation of the tin substrate under pressure during the gluing process. The accuracy of the spectral reflectance measurements were estimated to be ±0.5 μm, which was sufficient to demonstrate a convincing correlation between glue thickness and shock-generated light.
Date: September 20, 2010
Creator: Marshall, B. R.
Partner: UNT Libraries Government Documents Department

The Effect of High-Resistance SnO2 on CdS/CdTe Device Performance

Description: In this paper, we have studied the effect of high-resistance SnO2 buffer layers, deposited by low-pressure chemical-vapor deposition, on CdS/CdTe device performance. Our results indicate that when CdS/CdTe devices have a very thin layer of CdS or no CdS at all, the i-SnO2 buffer layer helps to increase device efficiency. When the CdS layer is thicker than 600{angstrom}, the device performance is dominated by CdS thickness, not the i-SnO2 layer. If a very thin CdS layer is to be used to enhance device performance, we conclude that a better SnO2 buffer layer is needed.
Date: October 6, 1998
Creator: Li, W.; Ribelin, R.; Mahathongdy, Y.; Albin, D.; Dhere, R.; Rose, D. et al.
Partner: UNT Libraries Government Documents Department

Shape from equal thickness contours

Description: A unique imaging modality based on Equal Thickness Contours (ETC) has introduced a new opportunity for 3D shape reconstruction from multiple views. We present a computational framework for representing each view of an object in terms of its object thickness, and then integrating these representations into a 3D surface by algebraic reconstruction. The object thickness is inferred by grouping curve segments that correspond to points of second derivative maxima. At each step of the process, we use some form of regularization to ensure closeness to the original features, as well as neighborhood continuity. We apply our approach to images of a sub-micron crystal structure obtained through a holographic process.
Date: May 10, 1998
Creator: Cong, G. & Parvin, B.
Partner: UNT Libraries Government Documents Department

Basin Analysis of the Mississippi Interior Salt Basin and Petroleum System Modeling of the Jurassic Smackover Formation, Eastern Gulf Coastal Plain, Final Report and Topical Reports 5-8 on Smackover Petroleum system and Underdevelopment Reservoirs

Description: The Smackover Formation, a major hydrocarbon-producing horizon in the Mississippi Interior Salt Basin (MISB), conformably overlies the Norphlet Formation and is conformably overlain by the Buckner Anhydrite Member of the Haynesville Formation. The Norphlet-Smackover contact can be either gradational or abrupt. The thickness and lithofacies distribution of the Smackover Formation were controlled by the configuration of incipient paleotopography. The Smackover Formation has been subdivided into three informal members, referred to as the lower, middle and upper members.
Date: March 5, 2002
Creator: Mancini, Ernest A.; Puckett, T. Markham; Parcell, William C.; Llinas, Juan Carlos; Kopaska-Merkel, David C. & Townsend, Roger N.
Partner: UNT Libraries Government Documents Department


Description: Ultra-high strength metallic multilayers are ideal for investigating the effects of length scales in plastic deformation of metallic materials. Experiments on model systems show that the strengths of these materials increase with decreasing bilayer period following the Hall-Petch model. However, as the layer thickness is reduced to the nm-scale, the number of dislocations in the pile-up approaches one and the pile-up based Hall-Petch model ceases to apply. For nm-scale semi-coherent multilayers, we hypothesize that plastic flow occurs by the motion of single dislocation loops, initially in the softer layer, that deposit misfit type dislocation arrays at the interface and transfer load to the harder phase. The stress concentration eventually leads to slip in the harder phase, overcoming the resistance from the misfit arrays at the interface. A model is developed within the framework of classical dislocation theory to estimate the strengthening from this mechanism. The model predictions are compared with experimentally measured strengths.
Date: December 1, 2000
Creator: MISRA, A. & HIRTH, J.
Partner: UNT Libraries Government Documents Department


Description: Curves are calculated and plotted to show maximum missile ranges from TNT changes cased with aluminum or steel of various thicknesses. The maxfmum initial missile velocity is assumed to be 10,000 fps. General trajectory formulas are derived from which the range may be calculated for any initial missile velocity, as determined from the ratio of the case weight to the explosive weight. (auth)
Date: July 1, 1958
Creator: Bishop, R.H.
Partner: UNT Libraries Government Documents Department

TOUGH+/GasH20 study of the effects of a heat source buried in theMartian permafrost

Description: We use TOUGH+/GasH2O to study the effects of a heat sourceburied in the Martian permafrost to evaluate the possibility ofestablishing a wet zone of liquid water, in which terrestrialmicroorganisms could survive and multiply. Analysis of the problemindicates that (1) only a limited permafrost volume (not exceeding 0.35 min radius) is affected, (2) a "wet" zone with limited amounts of liquidwater de-velops (not exceeding 8 and 0.7 kg for a 250 W and a 62.5 Wsource, respectively), (3) the wet zone per-sists for a long time,becomes practically stationary after t = 20 sols because of venting intothe Martian atmosphere, and its thickness is limited and decreases slowlyover time, (4) a "dry" zone (where SG>0.9) evolves, continues toexpand (albeit slowly) with time, but its extent remains limited, and (5)the ice front surrounding the wet zone is self-sharpening. For a range ofinitial conditions investigated, evolution of the liquid water massoccurs at approximately the same rate, reaches roughly the same maximum,and occurs at about the same time (10 to 20 sols; 1 sol = 24.39hours).
Date: May 12, 2006
Creator: Moridis, George J. & Pruess, Karsten
Partner: UNT Libraries Government Documents Department

Effects of Membrane- and Catalyst-layer-thickness Nonuniformitiesin Polymer-electrolyte Fuel Cells

Description: In this paper, results from mathematical, pseudo 2-D simulations are shown for four different along-the-channel thickness distributions of both the membrane and cathode catalyst layer. The results and subsequent analysis clearly demonstrate that for the membrane thickness distributions, cell performance is affected a few percent under low relative-humidity conditions and that the position along the gas channel is more important than the local thickness variations. However, for the catalyst-layer thickness distributions, global performance is not impacted, although for saturated conditions there is a large variability in the local temperature and performance depending on the thickness.
Date: September 1, 2006
Creator: Weber, Adam Z. & Newman, John
Partner: UNT Libraries Government Documents Department

Monitoring of Refractory Wall recession using high temperature impact echo instrumentation

Description: Regression of refractory linings of furnaces occurs due to a variety of mechanisms. The specific mechanism selected for investigation during this program is the regression of refractories which are in direct contact with a liquid corrodant. Examples include the melting of glass, the production of pig iron and steel, and the melting of aluminum. The rates of regression to a wall thickness which requires reline or extensive reconstruction vary widely, from less than a year to over ten years depending on the specific service environment. This program investigated the feasibility of measuring refractory wall thickness with an impact-echo method while at operating temperature (wall temperatures exceeding 500 C). The impact-echo method uses the impact of a small sphere with the surface of the test object to send a stress wave into the object. In a plate-like structure, the stress wave reflects back to the front surface, reverberating in the structure and causing a periodic surface displacement whose frequency is inversely proportional to the thickness of the test object. Impact-echo testing was chosen because it requires access to only one side of the test object and could be performed during the operation of a refractory structure. Commercially-available impact-echo instrumentation is available for room temperature use for a variety of tests on concrete. The enabling technology for this work was to use a high-temperature piezoelectric material, aluminum nitride, as the receiving sensor for the stress waves, allowing its use on refractories during furnace operation.
Date: April 30, 2004
Creator: Dayton, University of
Partner: UNT Libraries Government Documents Department

Inf-sup estimates for the Stokes problem in a periodic channel

Description: We derive estimates of the Babuska-Brezzi inf-sup constant {beta} for two-dimensional incompressible flow in a periodic channel with one flat boundary and the other given by a periodic, Lipschitz continuous function h. If h is a constant function (so the domain is rectangular), we show that periodicity in one direction but not the other leads to an interesting connection between {beta} and the unitary operator mapping the Fourier sine coefficients of a function to its Fourier cosine coefficients. We exploit this connection to determine the dependence of {beta} on the aspect ratio of the rectangle. We then show how to transfer this result to the case that h is C{sup 1,1} or even C{sup 0,1} by a change of variables. We avoid non-constructive theorems of functional analysis in order to explicitly exhibit the dependence of {beta} on features of the geometry such as the aspect ratio, the maximum slope, and the minimum gap thickness (if h passes near the substrate). We give an example to show that our estimates are optimal in their dependence on the minimum gap thickness in the C{sup 1,1} case, and nearly optimal in the Lipschitz case.
Date: December 10, 2008
Creator: Wilkening, Jon
Partner: UNT Libraries Government Documents Department


Description: A calculation is given of the radiated energy loss from a charged rod which moves at constant speed past an infinite set of parallel semi-infinite conducting plates of infinitesimal thickness, with the rod taken parallel to and at a fixed distance from the plate edges. The problem is analyzed using the Wiener-Hopf technique, and the resulting formulas are evaluated analytically in the limits of high rod speed and low rod speed, and compared with numerical evaluation over the full range of speeds.
Date: April 23, 1970
Creator: Hazeltine, R.D.; Rosenbluth, M.N. & Sessler, A.M.
Partner: UNT Libraries Government Documents Department

Electromagnetic Borehole Flowmeter Testing at the Southwest Plume Test Pad

Description: Multiple-well aquifer tests were recently conducted at the Southwest Plume Test Pad near the Burial Ground Complex (BGC) in accordance with the BGC Field Investigation Plan (WSRC, 1999). The pumping tests were performed in the Upper Three Runs and Gordon aquifers in February and March of 1999. The tests provide reliable estimates of horizontal conductivity averaged over aquifer thickness, and a relatively large horizontal zone of influence.
Date: January 29, 2001
Creator: Flach, G.P.
Partner: UNT Libraries Government Documents Department

Elastic shock response and spall strength of concrete

Description: Impact experiments have been performed to obtain shock compression, release response, and spall strength of two scaled concrete formulations. Wave profiles from a suite of ten experiments, with shock amplitudes of 0.08 to 0.55 GPa, focus primarily on the elastic regime. Despite considerable wave structure that develops at the shock transits these heterogeneous targets, consistent pullback signals were identified in the release profiles, indicating a spall strength of about 30 MPa. Explicit modeling of the concrete aggregate structure in numerical simulations provides insight into the particle velocity records.
Date: August 1, 1997
Creator: Kipp, M.E.; Chhabildas, L.C. & Reinhart, W.D.
Partner: UNT Libraries Government Documents Department

Estimating the Maximum Splat Diameter of a Solidifying Droplet

Description: We present a simple analytical model for the estimation of the maximum splat diameter of an impacting droplet on a subcooled target. This work is an extension of the isothermal model of Pasandideh-Fard et al. (1996). The model uses an energy conservation argument, applied between the initial and final drop configurations, to approximately capture the dynamics of spreading. The effects of viscous dissipation, surface tension, and contact angle are taken into account. Tests against limited experimental data at high Reynolds and Weber numbers indicate that an accuracy of the order of 5% is achieved with no adjustable parameters required. Agreement with experimental data in the limit We {yields} {infinity} is also very good. We additionally propose a simple model for the estimation of the thickness of the freezing layer developed at the droplet-substrate contact during droplet spreading. This model accounts for the effect of thermal contact resistance and its predictions compare favorably with experimental data.
Date: March 31, 1999
Creator: Hadjiconstantinou, N.G.
Partner: UNT Libraries Government Documents Department

ESP – Data from Restarted Life Tests of Various Silicone Materials - 2011

Description: Current funding has allowed the restart of testing of various silicone materials placed in Life Tests or Aging Studies from past efforts. Some of these materials have been in test since 1982, with no testing for approximately 10 years, until funding allowed the restart in FY97. This report will provide data on materials used in production and on experimental materials not used in production. Charts for the various materials at different thickness, compression, and temperature combinations illustrate trends for the load-bearing properties of the materials.
Date: December 31, 2011
Creator: Schneider, Jim
Partner: UNT Libraries Government Documents Department