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A nonlinear model of thermoelectricity with two temperatures: Application to quasicrystalline nanowires
A general two temperature nonlinear thermodynamic model to describe thermoelectric effects is introduced. Its compatibility with the second law of thermodynamics is investigated. We specialize the model in the framework of thermomass theory and estimate the maximum efficiency of a one-dimensional thermoelectric generator.
Monte Carlo Perturbation Analysis of Fuel Temperature Variations in the MCNP Model of the Annular Core Research Reactor
The Annular Core Research Reactor (ACRR) Monte Carlo N-Particle (MCNP) model is used by ACRR reactor operators and experiment designers at Sandia National Laboratories for a variety of computational calculations ranging from reactor kinetics parameter estimates and safety analyses to experimental planning. To understand the dominant source of uncertainty within the MCNP model, perturbations in temperature were applied to individual ACRR MCNP fuel rods. Fuel rod temperatures were randomly sampled from a uniform distribution from operational temperatures to quantify temperature-related uncertainty effects. Stochastic mixing was used to blend the cross sections of the desired temperatures using the MCNP continuous and Thermal Neutron Scattering Treatment [S(α,β)] libraries in ENDF/B-VII.1. Furthermore, this uncertainty analysis produced a 640 row × 640 column correlation and covariance matrix of the neutron energy spectra. Positive covariance was produced around the 1-MeV region and the 0.2-eV region. Correlation was found in the thermal and fast energy regions, but no correlation was observed in the slowing-down energy region because interactions in this region are not dominated by fuel.
Modeling Inside Storage Temperatures from Outside Weather Service Temperatures
Abstract Not Provided
Improved Axisymmetric and High Temperature Material Structural Modeling in MOOSE and NEML
This report describes improvements made to the solid mechanics formulation in the MOOSE open source finite element simulation environment and the open source Nuclear Engineering Material model Library (NEML) for mechanical constitutive models. The focus of these improvements is to improve the usability and performance of simulations involving one or both pieces of software. Specifically, this work completes a new system for solid mechanics simulations in the MOOSE ecosystem providing exact linearizations and optimal (quadratic) convergence, for a variety of coordinate systems and material types, including large deformation simulations. This work then provides users a framework to build highly efficient mechanical simulations of structures or materials or to couple in additional MOOSE physics modules to build complex, scalable multiphysics simulations.
Genetic Algorithm Optimization of A Theory-Based Low-Temperature Cyclopentane Oxidation Model.
Abstract not provided.
Modeling Assisted Room Temperature Operation of Atomic Precision Advanced Manufacturing Devices.
Abstract not provided.
Stress and Strain Modeling of Low Temperature Cofired Ceramic (LTCC) Seal Frame and Lid
Low temperature cofired ceramic (LTCC) is established as an excellent packaging technology for high reliability, high density microelectronics. LTCC multichip modules (MCMs) comprising both ‘surface mount’ and ‘chip and wire’ technologies provide additional customization for performance. Long term robustness of the packages is impacted by the selection of seal frame and lid materials used to enclose the components inside distinct rooms in LTCC MCMs. An LTCC seal frame and lid combination has been developed that is capable of meeting the sealing and electromagnetic shielding requirements of MCMs. Here, we analyze the stress and strain performance of various seal frame and lid materials, sealing materials, and configurations. The application for the MCM will affect selection of the seal frame, lid, and sealing materials based on this analysis.
Interactive initialization of heat flux parameters for numerical models using satellite temperature measurements
Day/night Heat Capacity Mapping Mission image pairs over Kansas and Indiana were used to examine the spatial variation of moisture availability on the mesoscale. Of particular concern was whether patterns of moisture availability and thermal inertia, as well as surface heat fluxes, respond to significant spatial variations in the rainfall pattern. A temperature analysis for the Indiana case is presented.
Interactive initialization of heat flux parameters for numerical models using satellite temperature measurements
Progress made in HCMM research, including testing the interactive minicomputer system and preparation of a paper on the analysis of regional scale soil moisture patterns, is summarized. An exhibit on remote sensing including a videotape display of HCMM images, most of them of the State College area, was prepared.
Considerations in development and implementation of elasto-viscoplastic constitutive model for high temperature applications
The prediction of inelastic behavior of metallic materials at elevated temperatures has increased in importance in recent years. The operating conditions within the hot section of a rocket motor or a modern gas turbine engine present an extremely harsh thermomechanical environment. Large thermal transients are induced each time the engine is started or shut down. Additional thermal transients from an elevated ambient occur whenever the engine power level is adjusted to meet flight requirements. The structural elements employed in such hot sections, as well as any engine components located therein, must be capable of withstanding such extreme conditions. Failure of a component would, due to the critical nature of the hot section, lead to an immediate and catastrophic loss in power. Consequently, assuring satisfactory long term performance for such components is a major concern. Nonisothermal loading of structures often causes excursion of stress well into the inelastic range. Moreover, the influence of geometry changes on the response is also significant in most cases. Therefore, both material and geometric nonlinear effects are considered.
Gamma-Ray Spectra and Variability of Cygnus Z-1 Observed by BATSE
We present new BATSE earth occultation observations of the 25 keV-1.8 MeV spectrum and variability of Cygnus X-1 made between August 1993 and May 1994. We observed that the normal soft gamma ray spectrum (gamma2) of Cygnus X-1 has two components: a Comptonized part seen below 300 keV, and a high-energy tail in the 0.3 - 2 MeV range. We interpret it in terms of a two-layer region, consisting of a high-energy core (with an equivalent electron temperature of approximately 210-250 keV) near the event horizon, embedded in an about 50 keV corona. In this scenario, the observed 25-300 keV photons were produced by Compton scattering of soft photons (about 0.5 keV) by the hot electrons in the outer corona. These same hard x rays were further up-scattered by a population of energetic electrons in the inner core, producing the spectral tail above 300 keV. Cygnus X-1 went through an extended sequence of transitions between August 1993 and May 1994, when the 45-140 keV flux first decreased steadily from approximately gamma2 to roughly one-quarter of its intensity over a period of about 140 days. The flux remained at this low level for about 40 days before returning, swiftly (approximately 20 days) to approximately the initial gamma2 level. During the transition, the spectrum evolved to a shape consistent with either a power law with photon index of about 2.6 or a single temperature Compton model with electron temperature kT = 110 +/- 11 keV, and optical depth t = 0.40 +/- 0.06, and then returned essentially to the original gamma2 spectrum at the end of the active period. The overall cooling of the system during the low flux period may be due to an increase in the soft photon population which effectively quenched the hot electrons in these regions through Compton scattering.
Soil Moisture Controls on Rainfall and Temperature Variability: A Modeler Searches Through Observational Data
The degree to which atmospheric processes respond to variations in soil moisture - a potentially important but largely untapped element of subseasonal to seasonal prediction - can be determined easily and directly for an atmospheric model but cannot be determined directly for nature through an analysis of observations. In atmospheric models) directions of causality can be artificially manipulated; we can avoid difficulties associated with the fact that atmospheric variations have a much larger impact on land state variations than vice-versa. In nature) on the other hand) the dominant direction of causality (the atmosphere forcing the ground) cannot be artificially "turned off") and the statistics associated with this dominant direction overwhelm those of the feedback signal. Observational data) however) do allow a number of indirect measures of landatmosphere feedback. This seminar reports on a series of joint analyses of observational and model data designed to illuminate the degree of land-atmosphere feedback present in the real world. The indirect measures do in fact suggest that feedback in nature, though small) is significant - enough to warrant the development of realistic land initialization strategies for subseasonal and seasonal forecasts.
Temperature Knowledge and Model Correlation for the Soil Moisture Active and Passive (SMAP) Reflector Mesh
No abstract available
A Multivibrational Mode Relaxation Scheme for Two-Temperature Thermochemical State Models
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A simple model for closure temperature of a trace element in cooling bi-mineralic systems
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On the Accuracy of Reconstructing Plasma Sheet Electron Fluxes From Temperature and Density Models
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Extension of the WIPP Actinide Oxidation State Analog Models to Elevated Temperatures Under Reducing Conditions.
Abstract not provided.