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3-D DETERMINISTIC TRANSPORT METHODS RESEARCH AT LANL UNDER ASCI

3-D DETERMINISTIC TRANSPORT METHODS RESEARCH AT LANL UNDER ASCI

Date: January 1, 2000
Creator: Morel, J.
Description: No abstract prepared.
Contributing Partner: UNT Libraries Government Documents Department
3-D elastic wave scattering by a layer containing vertical periodic fractures

3-D elastic wave scattering by a layer containing vertical periodic fractures

Date: April 30, 2002
Creator: Nakagawa, Seiji; Nihei, Kurt T.; Myer, Larry R. & Majer, Ernest L.
Description: No abstract prepared.
Contributing Partner: UNT Libraries Government Documents Department
3-D electromagnetic modeling of wakefields in accelerator components

3-D electromagnetic modeling of wakefields in accelerator components

Date: September 18, 1996
Creator: Poole, B.R.; Caporaso, G.J.; Ng, Wang C.; Shang, C.C. & Steich, D.
Description: We discuss the use of 3-D finite-difference time-domain (FDTD) electromagnetic codes for modeling accelerator components. Computational modeling of cylindrically symmetric structures such as induction accelerator cells has been very successful in predicting the wake potential and wake impedances of these structures, but full 3-D modeling of complex structures has been limited due to substantial computer resources required for a full 3-D model. New massively parallel 3-D time domain electromagnetic codes now under development using conforming unstructured meshes allow a substantial increase in the geometric fidelity of the structures being modeled. Development of these new codes are discussed in context of applicability to accelerator problems. Various 3-D structures are tested with an existing cubical cell FDTD code and wake impedances compared with simple analytic models for the structures; results will be used as benchmarks for testing the new time time domain codes. Structures under consideration include a stripline beam position monitor as well as circular and elliptical apertures in circular waveguides. Excellent agreement for monopole and dipole impedances with models were found for these structures below the cutoff frequency of the beam line.
Contributing Partner: UNT Libraries Government Documents Department
3-D Experimental Fracture Analysis at High Temperature

3-D Experimental Fracture Analysis at High Temperature

Date: September 14, 2001
Creator: Jackson, John H. & Kobayashi, Albert S.
Description: T*e, which is an elastic-plastic fracture parameter based on incremental theory of plasticity, was determined numerically and experimentally. The T*e integral of a tunneling crack in 2024-T3 aluminum, three point bend specimen was obtained through a hybrid analysis of moire interferometry and 3-D elastic-plastic finite element analysis. The results were verified by the good agreement between the experimentally and numerically determined T*e on the specimen surface.
Contributing Partner: UNT Libraries Government Documents Department
3-D field computation: The near-triumph of commerical codes

3-D field computation: The near-triumph of commerical codes

Date: July 1995
Creator: Turner, L. R.
Description: In recent years, more and more of those who design and analyze magnets and other devices are using commercial codes rather than developing their own. This paper considers the commercial codes and the features available with them. Other recent trends with 3-D field computation include parallel computation and visualization methods such as virtual reality systems.
Contributing Partner: UNT Libraries Government Documents Department
3-D Finite Element Analyses of the Egan Cavern Field

3-D Finite Element Analyses of the Egan Cavern Field

Date: February 1, 1999
Creator: Klamerus, E.W. & Ehgartner, B.L.
Description: Three-dimensional finite element analyses were performed for the two gas-filled storage caverns at the Egan field, Jennings dome, Louisiana. The effects of cavern enlargement on surface subsidence, storage loss, and cavern stability were investigated. The finite element model simulated the leaching of caverns to 6 and 8 billion cubic feet (BCF) and examined their performance at various operating conditions. Operating pressures varied from 0.15 psi/ft to 0.9 psi/ft at the bottom of the lowest cemented casing. The analysis also examined the stability of the web or pillar of salt between the caverns under differential pressure loadings. The 50-year simulations were performed using JAC3D, a three dimensional finite element analysis code for nonlinear quasistatic solids. A damage criterion based on onset of dilatancy was used to evaluate cavern instability. Dilation results from the development of microfractures in salt and, hence, potential increases in permeability onset occurs well before large scale failure. The analyses predicted stable caverns throughout the 50-year period for the range of pressures investigated. Some localized salt damage was predicted near the bottom walls of the caverns if the caverns are operated at minimum pressure for long periods of time. Volumetric cavern closures over time due to creep were ...
Contributing Partner: UNT Libraries Government Documents Department
3-D Finite Element Analysis of Induction Logging in a Dipping Formation

3-D Finite Element Analysis of Induction Logging in a Dipping Formation

Date: July 20, 2000
Creator: EVERETT,MARK E.; BADEA,EUGENE A.; SHEN,LIANG C.; MERCHANT,GULAMABBAS A. & WEISS,CHESTER J.
Description: Electromagnetic induction by a magnetic dipole located above a dipping interface is of relevance to the petroleum well-logging industry. The problem is fully three-dimensional (3-D) when formulated as above, but reduces to an analytically tractable one-dimensional (1-D) problem when cast as a small tilted coil above a horizontal interface. The two problems are related by a simple coordinate rotation. An examination of the induced eddy currents and the electric charge accumulation at the interface help to explain the inductive and polarization effects commonly observed in induction logs from dipping geological formations. The equivalence between the 1-D and 3-D formulations of the problem enables the validation of a previously published finite element solver for 3-D controlled-source electromagnetic induction.
Contributing Partner: UNT Libraries Government Documents Department
3-d finite element model development for biomechanics: a software demonstration

3-d finite element model development for biomechanics: a software demonstration

Date: March 1, 1997
Creator: Hollerbach, K.; Hollister, A.M. & Ashby, E.
Description: Finite element analysis is becoming an increasingly important part of biomechanics and orthopedic research, as computational resources become more powerful, and data handling algorithms become more sophisticated. Until recently, tools with sufficient power did not exist or were not accessible to adequately model complicated, three-dimensional, nonlinear biomechanical systems. In the past, finite element analyses in biomechanics have often been limited to two-dimensional approaches, linear analyses, or simulations of single tissue types. Today, we have the resources to model fully three-dimensional, nonlinear, multi-tissue, and even multi-joint systems. The authors will present the process of developing these kinds of finite element models, using human hand and knee examples, and will demonstrate their software tools.
Contributing Partner: UNT Libraries Government Documents Department
3-D Force-balanced Magnetospheric Configurations

3-D Force-balanced Magnetospheric Configurations

Date: February 10, 2003
Creator: Zaharia, Sorin; Cheng, C. Z. & Maezawa, K.
Description: The knowledge of plasma pressure is essential for many physics applications in the magnetosphere, such as computing magnetospheric currents and deriving magnetosphere-ionosphere coupling. A thorough knowledge of the 3-D pressure distribution has however eluded the community, as most in-situ pressure observations are either in the ionosphere or the equatorial region of the magnetosphere. With the assumption of pressure isotropy there have been attempts to obtain the pressure at different locations by either (a) mapping observed data (e.g., in the ionosphere) along the field lines of an empirical magnetospheric field model or (b) computing a pressure profile in the equatorial plane (in 2-D) or along the Sun-Earth axis (in 1-D) that is in force balance with the magnetic stresses of an empirical model. However, the pressure distributions obtained through these methods are not in force balance with the empirical magnetic field at all locations. In order to find a global 3-D plasma pressure distribution in force balance with the magnetospheric magnetic field, we have developed the MAG-3D code, that solves the 3-D force balance equation J x B = (upside-down delta) P computationally. Our calculation is performed in a flux coordinate system in which the magnetic field is expressed in terms ...
Contributing Partner: UNT Libraries Government Documents Department
3-D full waveform inversion of seismic data; Part I. Theory

3-D full waveform inversion of seismic data; Part I. Theory

Date: May 12, 2003
Creator: Lee, Ki Ha
Description: Full waveform inversion of seismic data is a challenging subject partly because of the lack of precise knowledge of the source. Since currently available approaches involve some form of approximations to the source, inversion results are subject to the quality and the choice of the source information used. A new full waveform inversion scheme has been introduced (Lee and Kim, 2003) using normalized wavefield for simple two-dimensional (2-D) scalar problems. The method does not require source information, so potential inversion errors due to source estimation may be eliminated. A gather of seismic traces is first Fourier-transformed into the frequency domain and a normalized wavefield is obtained for each trace in the frequency domain. Normalization is done with respect to the frequency response of a reference trace selected from the gather, so the complex-valued normalized wavefield is source-independent and dimensionless. The inversion algorithm minimizes misfits between measured normalized wavefield and numerically computed normalized wavefield. In this paper the full waveform inversion is extended to three-dimensional (3-D) problems.
Contributing Partner: UNT Libraries Government Documents Department