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On the response of rubbers at high strain rates.

Description: In this report, we examine the propagation of tensile waves of finite deformation in rubbers through experiments and analysis. Attention is focused on the propagation of one-dimensional dispersive and shock waves in strips of latex and nitrile rubber. Tensile wave propagation experiments were conducted at high strain-rates by holding one end fixed and displacing the other end at a constant velocity. A high-speed video camera was used to monitor the motion and to determine the evolution of strai… more
Date: February 1, 2010
Creator: Niemczura, Johnathan Greenberg (University of Texas-Austin)
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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DERIVATIONS FOR HOOP STRESSES DUE TO SHOCK WAVES IN A TUBE

Description: Equations describing the hoop stresses in a pipe due to water hammer have been presented in the literature in a series of papers, and this paper discusses the complete derivation of the pertinent equation. The derivation considers the pipe wall response to a water hammer induced shock wave moving along the inner wall of the pipe. Factors such as fluid properties, pipe wall materials, pipe dimensions, and damping are considered. These factors are combined to present a single, albeit rather compl… more
Date: April 30, 2007
Creator: Leishear, R
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Model-based Layer Estimation using a Hybrid Genetic/Gradient Search Optimization Algorithm

Description: A particle swarm optimization (PSO) algorithm is combined with a gradient search method in a model-based approach for extracting interface positions in a one-dimensional multilayer structure from acoustic or radar reflections. The basic approach is to predict the reflection measurement using a simulation of one-dimensional wave propagation in a multi-layer, evaluate the error between prediction and measurement, and then update the simulation parameters to minimize the error. Gradient search met… more
Date: May 17, 2007
Creator: Chambers, D.; Lehman, S. & Dowla, F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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SEISMIC AND ROCK PHYSICS DIAGNOSTICS OF MULTISCALE RESERVOIR TEXTURES

Description: As part of our study on ''Relationships between seismic properties and rock microstructure'', we have studied (1) How to quantify elastic properties of clay minerals using Atomic Force Acoustic Microscopy. We show how bulk modulus of clay can be measured using atomic force acoustic microscopy (AFAM) (2) We have successfully measured elastic properties of unconsolidated sediments in an effort to quantify attributes for detection of overpressures from seismic (3) We have initiated efforts for vel… more
Date: May 1, 2002
Creator: Mavko, Gary
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Beat-wave generation of plasmons in semiconductor plasmas

Description: It is shown that in semiconductor plasmas, it is possible to generate large amplitude plasma waves by the beating of two laser beams with frequency difference close to the plasma frequency. For narrow gap seimconductors (for example n-type InSb), the system can simulate the physics underlying beat wave generation in relativistic gaseous plasmas.
Date: August 1, 1995
Creator: Berezhiani, V. I. & Mahajan, S. M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Two-Dimensional Finite-Difference Modeling of Broadband Regional Wave Propagation Phenomena: Validation of Regional Three-Dimensional Earth Models and Prediction of Anomalous Regional Phases

Description: An important challenge for seismic monitoring of nuclear explosions at low magnitude to verify a nuclear-test-ban treaty is the development of techniques that use regional phases for detection, location, and identification. In order to use such phases, region-specific earth models and tools are needed that accurately predict features such as travel times, amplitudes, and spectral characteristics. In this paper, we present our efforts to use two-dimensional finite-difference modeling to help dev… more
Date: July 18, 2000
Creator: Goldstein, P; Ryall, F D; Pasyanos, M E; Schultz, C A & Walter, W R
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Simulation of penetration into porous geologic media

Description: We present a computational study on the penetration of steel projectiles into porous geologic materials. The purpose of the study is to extend the range of applicability of a recently developed constitutive model to simulations involving projectile penetration into geologic media. The constitutive model is non-linear, thermodynamically consistent, and properly invariant under superposed rigid body motions. The equations are valid for large deformations and they are hyperelastic in the sense tha… more
Date: May 31, 2005
Creator: Vorobiev, O Y; Liu, B T; Lomov, I N & Antoun, T
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Theoretical analysis of the shock-induced phase transition in iron

Description: We have studied the metastability and dynamics of the shock-induced {alpha} + {epsilon} phase transition in iron. Regarding metastability, it has long been known that the experimental Hugoniot does not agree with the theoretical equilibrium Hugoniot in the two-phase region above 13 GPa. We present a physically based construction of the metastable phase transition surface, and show that this surface is essentially the same in shocks as in quasistatic diamond-cell experiments. Regarding dynamics,… more
Date: November 1, 1997
Creator: Wallace, D. & Boettger, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Measurements of transient electromagnetic propagation through concrete and sand

Description: This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). If a beam-chopping system could be developed for the Los Alamos Meson Physics Facility low-energy beam line, there would be potential to operate the Los Alamos Neutron Scattering Center (LANSCE) at much higher power and duty factor and enable such operation with a radio-frequency quadrapole (RFQ) injector. This would greatly extend the capability of t… more
Date: September 1, 1996
Creator: Aurand, J. F.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Collisionless damping of perpendicular magnetosonic waves in a two-ion-species plasma

Description: Propagation of finite-amplitude magnetosonic waves in a collisionless plasma containing two ion species is studied with a one-dimensional, fully electromagnetic code based on a three-fluid model. It is found that perpendicular magnetosonic waves are damped in a two-ion-species plasma; a magnetosonic pulse accelerates heavy ions in the direction parallel to the wave front, which results in the excitation of a longer wavelength perturbation behind the pulse. The damping due to the energy transfer… more
Date: August 1, 1996
Creator: Dogen, Daiju; Toida, Mieko & Ohsawa, Yukiharu
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Discrete approximations of detonation flows with structured detonation reaction zones by discontinuous front models: A program burn algorithm based on detonation shock dynamics

Description: In the design of explosive systems the generic problem that one must consider is the propagation of a well-developed detonation wave sweeping through an explosive charge with a complex shape. At a given instant of time the lead detonation shock is a surface that occupies a region of the explosive and has a dimension that is characteristic of the explosive device, typically on the scale of meters. The detonation shock is powered by a detonation reaction zone, sitting immediately behind the shock… more
Date: February 2, 1999
Creator: Bdzil, John B.; Jackson, Thomas L. & Stewart, D. Scott
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Shear flow induced wave couplings in the solar wind

Description: A sheared background flow in a plasma induces coupling between different MHD wave modes, resulting in their mutual transformations with corresponding energy redistributing between the modes. In this way, the energy can be transfered from one wave mode to the other, but energy can also be added to or extracted from the background flow. In the present paper it is investigated whether the wave coupling and energy transfer mechanisms can operate under solar wind conditions. It is shown that this is… more
Date: January 1, 1998
Creator: Poedts, Stefaan; Rogava, Andria D. & Mahajan, Swadesh M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Prediction of violent mechanochemical processes

Description: Energetic materials, such as high explosives, propellants and ballotechnics, are widely used as energy sources in the design of numerous devices, components and processes. Although most energetic materials are selected for safe operation, their high energy densities have the potential for inadvertent initiation and subsequent powerful energy transformations. This potential for damage or injury places a heavy burden on careful analysis of safety issues as part of the design process. As a result,… more
Date: January 1, 1997
Creator: Graham, R. A.; Anderson, M. U.; Holman, G. T. & Baer, M. R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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BBN technical memorandum W1291 infrasound model feasibility study

Description: The purpose of this study is to determine the need and level of effort required to add existing atmospheric databases and infrasound propagation models to the DOE`s Hydroacoustic Coverage Assessment Model (HydroCAM) [1,2]. The rationale for the study is that the performance of the infrasound monitoring network will be an important factor for both the International Monitoring System (IMS) and US national monitoring capability. Many of the technical issues affecting the design and performance of … more
Date: May 1, 1998
Creator: Farrell, T., BBN Systems and Technologies
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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On Resonant Heating Below the Cyclotron Frequency

Description: Resonant heating of particles by an electrostatic wave propagating perpendicular to a confining uniform magnetic field is examined. It is shown that, with a sufficiently large wave amplitude, significant perpendicular stochastic heating can be obtained with wave frequency at a fraction of the cyclotron frequency.
Date: February 2, 2001
Creator: Chen, Liu; Lin, Zhihong & White, R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Characterization and application of microearthquake clusters to problems of scaling, fault zone dynamics, and seismic monitoring at Parkfield, California

Description: This document contains information about the characterization and application of microearthquake clusters and fault zone dynamics. Topics discussed include: Seismological studies; fault-zone dynamics; periodic recurrence; scaling of microearthquakes to large earthquakes; implications of fault mechanics and seismic hazards; and wave propagation and temporal changes.
Date: October 1, 1995
Creator: Nadeau, R. M.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Elastic wave propagation and attenuation in a double-porosity dual-permeability medium

Description: To account for large-volume low-permeability storage porosity and low-volume high-permeability fracture/crack porosity in oil and gas reservoirs, phenomenological equations for the poroelastic behavior of a double porosity medium have been formulated and the coefficients in these linear equations identified. The generalization from a single porosity model increases the number of independent inertial coefficients from three to six, the number of independent drag coefficients from three to six, a… more
Date: October 12, 1998
Creator: Berryman, J.G. & Wang, H.F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Wave propagation modeling capabilities at LLNL: Applications to regional discrimination

Description: A primary goal of our research at LLNL has been to develop an assemblage of the most promising numerical techniques for simulating regional wave propagation through complex media. These numerical capabilities will be an integral part of our approach to regional characterization in both the Middle East and North Africa. In this paper, we focus on demonstrating and validating our current modeling capabilities, which include reflectivity, boundary integral, finite-difference, along with hybrid for… more
Date: July 1, 1995
Creator: Schultz, C.A.; Larsen, S.C.; Goldstein, P. & Ruppert, S.D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Seismic Surface-Wave Tomography of Waste Sites

Description: Surface-wave group-velocity tomography is an efficient way to obtain images of the group velocity over a test area. Because Rayleigh-wave group velocity depends on frequency, there are separate images for each frequency. Thus, at each point in these images the group velocities define a dispersion curve, a curve that relates group velocity to frequency. The objective of this study has been to find an accurate and efficient way to find the shear-wave structure from these dispersion curves. The co… more
Date: December 17, 2002
Creator: Long, Leland Timothy
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Seismic waves in rocks with fluids and fractures

Description: Seismic wave propagation through the earth is often stronglyaffected by the presence of fractures. When these fractures are filledwith fluids (oil, gas, water, CO2, etc.), the type and state of the fluid(liquid or gas) can make a large difference in the response of theseismic waves. This paper summarizes recent work on methods ofdeconstructing the effects of fractures, and any fluids within thesefractures, on seismic wave propagation as observed in reflection seismicdata. One method explored he… more
Date: May 14, 2007
Creator: Berryman, J.G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Shock wave studies of snow

Description: Shock-wave studies of snow have been conducted at stress levels of up to 40 MPa. Analysis of embedded gauges and shock-reverberation techniques were used to determine shock pressure-density data for snow with initial densities ranging from 100 kg m{sup {minus}3} to 520 kg m{sup {minus}3} and temperatures ranging from {minus}2{degrees}C to {minus}23{degrees}C. Shock velocities ranged from about 170 m s{sup {minus}1} (for low density snow) to about 280 m s{sup {minus}1} (for high density snow). A… more
Date: January 1, 1991
Creator: Johnson, J. B.; Blaisdell, G. L.; Sturm, M.; Barrett, S. A.; Brown, J. A. & Gaffney, E. S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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NRL HF propagation mesurements between Guadeloupe and Providenciales during the CRRES exercises

Description: During this experiment series, scientists from NRL and LANL deployed high frequency radio transmitters on the Caribbean island of Guadeloupe and receiving equipment on the island of Providenciales in the Turks and Caicos Islands. The objective of these tests was twofold: (1) to determine the effect of injecting chemical agents known to affect the ambient plasma into a region of the ionospheric F layer subject to {open_quotes}heating{close_quotes} by HF radiowaves (2) to assess the effect of the… more
Date: May 1, 1994
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Body-wave radiation patterns and AVO in transversely isotropic media

Description: It is well known that the angular dependence of reflection coefficients may be significantly distorted in the presence of elastic anisotropy. However, the influence of anisotropy on amplitude-versus-offset analysis (AVO) is not limited to reflection coefficients. AVO signatures (e.g., AVO gradient) in anisotropic media are also distorted by the redistribution of energy along the wavefront of the wave travelling down to the reflector and back up to the surface. Significant anisotropy above the t… more
Date: March 1994
Creator: Tsvankin, I.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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