Inelastic Constitutive Properties and shear Localization in Tennessee Marble

Shear bands and faults are ubiquitous features of brittle rock deformation at a variety of length scales. Despite the prevalence of these features, understandhg of their inception remains rudimentary. Laboratory experiments suggest a casual association of localization of deformation (faulting) with peak stress, but more detailed examination reveals that localization can precede or follow the peak. Rudnicki and Rice (1975, hereafter abbreviated as RR) have suggested a the- ory of the inception of localization as a bifurcation or nonuniqueness of the so- lution for homogeneous deformation. They predict a strong dependence of local- ization on deformation state. In particular, they predict that localization can occur prepeak for deformation states near deviatoric pure shear and does not occur until well after peak for axisymmetric compression. This prediction is roughly in ac- cord with the true triaxial experiments of Mogi (1967, 1971). More recently, Ord et al. (1991) and Wwersik et al. (1991) have reported observations of localization prior to peak stress in plane strain experiments. The predictions of RR depend strongly on the constitutive properties of the rock and detailed comparison has been impeded by inadequate knowledge of those properties. Even the idealized constitutive model used by RR requires knowledge of the evolution of the constitutive properties with inelastic deformation that is not readily obtainable from the typical axisymmetric compression test. Although it is conceptually advantageous to consider inelastic deformation at fixed mean stress, the mean stress changes throughout the axisymmetric compression test. In this paper, we present a synthesis of a number of axisymmetric compres- sion tests to extract a detailed implementation of the constitutive framework used by RR. The resulting constitutive relation is then used to -predict the response for plane strain. Conditions for localization of deformation derived by RR are evalu- ated for both plane strain and axisymmetric compression

Unique N170 Signatures to Words and Faces in Deaf ASL Signers Reflect Experience-Specific Adaptations During Early Visual Processing

Previous studies with deaf adults reported reduced N170 waveform asymmetry to visual words, a finding attributed to reduced phonological mapping in left-hemisphere temporal regions compared to hearing adults. An open question remains whether this pattern indeed results from reduced phonological processing or from general neurobiological adaptations in visual processing of deaf individuals. Deaf ASL signers and hearing nonsigners performed a same-different discrimination task with visually presented words, faces, or cars, while scalp EEG time-locked to the onset of the first item in each pair was recorded. For word recognition, the typical left-lateralized N170 in hearing participants and reduced left-sided asymmetry in deaf participants were replicated. The groups did not differ on word discrimination but better orthographic skill was associated with larger N170 in the right hemisphere only for deaf participants. Face recognition was characterized by unique N170 signatures for both groups, and deaf individuals exhibited superior face discrimination performance. Laterality or discrimination performance effects did not generalize to the N170 responses to cars, confirming that deaf signers are not inherently less lateralized in their electrophysiological responses to words and critically, giving support to the phonological mapping hypothesis. P1 was attenuated for deaf participants compared to the hearing, but in both groups, P1 selectively discriminated between highly learned familiar objects – words and faces versus less familiar objects – cars. The distinct electrophysiological signatures to words and faces reflected experience-driven adaptations to words and faces that do not generalize to object recognition

Disposable fiber optics telemetry for measuring while drilling

The project addressed the need of the oil and gas industry for real-time information about the drilling process and the formations being drilled. An ideal system would allow measuring while drilling (MWD) and would transmit data to the surface immediately at a rate high enough to support video or televiewer systems. A proposed solution was to use an optical fiber as a link between the surface and the instrumentation package. We explored the use of a disposable MWD telemetry cable, drawing on the technology developed for missile guidance which deploys miles of fiber from a small spool at missile speeds approaching half the speed of sound. Emphasis In was on the questions of survivability of the unarmored fiber in the drill string environment and deployability. Laboratory and field testing showed the concept worked under realistic conditions; a field demonstration transmitted data at 10 kilobits per second from a depth of 3500 feet

AHTR Refueling Systems and Process Description

The Advanced High-Temperature Reactor (AHTR) is a design concept for a central station-type [1500 MW(e)] Fluoride salt-cooled High-temperature Reactor (FHR) that is currently undergoing development by Oak Ridge National Laboratory for the US. Department of Energy, Office of Nuclear Energy's Advanced Reactor Concepts program. FHRs, by definition, feature low-pressure liquid fluoride salt cooling, coated-particle fuel, a high-temperature power cycle, and fully passive decay heat rejection. The overall goal of the AHTR development program is to demonstrate the technical feasibility of FHRs as low-cost, large-size power producers while maintaining full passive safety. The AHTR is approaching a preconceptual level of maturity. An initial integrated layout of its major systems, structures, and components (SSCs), and an initial, high-level sequence of operations necessary for constructing and operating the plant is nearing completion. An overview of the current status of the AHTR concept has been recently published and a report providing a more detailed overview of the AHTR structures and mechanical systems is currently in preparation. This report documents the refueling components and processes envisioned at this early development phase. The report is limited to the refueling aspects of the AHTR and does not include overall reactor or power plant design information. The report, however, does include a description of the materials envisioned for the various components and the instrumentation necessary to control the refueling process. The report begins with an overview of the refueling strategy. Next a mechanical description of the AHTR fuel assemblies and core is provided. The reactor vessel upper assemblies are then described. Following this the refueling path structures and the refueling mechanisms and components are described. The sequence of operations necessary to fuel and defuel the reactor is then discussed. The report concludes with a discussion of the levels of maturity of the various SSCs to provide guidance for future technology developments. The conceptual design information presented in this report is very preliminary in nature. Significant uncertainty remains about several aspects of the process and even the radiation and mechanical performance of plate-type coated-particle fuel

Electrodynamics of Media

Contains research objectives, summary of research and reports on two research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300U. S. Army Research Office - Durham (Contract l)AHC04-72-C-0044)California Institute of Technology Contract 953524M.I.T. Sloan Fund for Basic Researc

HTGR Measurements and Instrumentation Systems

This report provides an integrated overview of measurements and instrumentation for near-term future high-temperature gas-cooled reactors (HTGRs). Instrumentation technology has undergone revolutionary improvements since the last HTGR was constructed in the United States. This report briefly describes the measurement and communications needs of HTGRs for normal operations, maintenance and inspection, fuel fabrication, and accident response. The report includes a description of modern communications technologies and also provides a potential instrumentation communications architecture designed for deployment at an HTGR. A principal focus for the report is describing new and emerging measurement technologies with high potential to improve operations, maintenance, and accident response for the next generation of HTGRs, known as modular HTGRs, which are designed with passive safety features. Special focus is devoted toward describing the failure modes of the measurement technologies and assessing the technology maturity

The Effects of High Volume Aquatic Plyometric Training on Vertical Jump, Muscle Power, and Torque

The purpose of this study was to examine the effects of high volume aquatic-based plyometrics versus lower volume land and aquatic plyometric training on vertical jump (VJ), muscular peak power and torque in the dominant knee. Thirty-nine adult participants were randomly assigned to 1 of 4 groups: aquatic group 1 (APT1), aquatic group 2 (APT2), land group (LPT1), and control group (CON). All groups performed a 6-week plyometric training program. The APT1 and LPT performed the same volume of training where, APT2 doubled the volume. All participants were pre- and post-tested on performance variables. A 4 (group) X 2 (time) ANOVA with repeated measures was used to determine differences between the performance variables. We found no significant differences between groups for all tested variables. However, APT2 showed the greatest increased average in the performance variables. The high volume aquatic plyometric protocol is useful to help increase performance and minimize muscle soreness

Advanced High Temperature Reactor Systems and Economic Analysis

The Advanced High Temperature Reactor (AHTR) is a design concept for a large-output [3400 MW(t)] fluoride-salt-cooled high-temperature reactor (FHR). FHRs, by definition, feature low-pressure liquid fluoride salt cooling, coated-particle fuel, a high-temperature power cycle, and fully passive decay heat rejection. The AHTR's large thermal output enables direct comparison of its performance and requirements with other high output reactor concepts. As high-temperature plants, FHRs can support either high-efficiency electricity generation or industrial process heat production. The AHTR analysis presented in this report is limited to the electricity generation mission. FHRs, in principle, have the potential to be low-cost electricity producers while maintaining full passive safety. However, no FHR has been built, and no FHR design has reached the stage of maturity where realistic economic analysis can be performed. The system design effort described in this report represents early steps along the design path toward being able to predict the cost and performance characteristics of the AHTR as well as toward being able to identify the technology developments necessary to build an FHR power plant. While FHRs represent a distinct reactor class, they inherit desirable attributes from other thermal power plants whose characteristics can be studied to provide general guidance on plant configuration, anticipated performance, and costs. Molten salt reactors provide experience on the materials, procedures, and components necessary to use liquid fluoride salts. Liquid metal reactors provide design experience on using low-pressure liquid coolants, passive decay heat removal, and hot refueling. High temperature gas-cooled reactors provide experience with coated particle fuel and graphite components. Light water reactors (LWRs) show the potentials of transparent, high-heat capacity coolants with low chemical reactivity. Modern coal-fired power plants provide design experience with advanced supercritical-water power cycles. The current design activities build upon a series of small-scale efforts over the past decade to evaluate and describe the features and technology variants of FHRs. Key prior concept evaluation reports include the SmAHTR preconceptual design report,1 the PB-AHTR preconceptual design, and the series of early phase AHTR evaluations performed from 2004 to 2006. This report provides a power plant-focused description of the current state of the AHTR. The report includes descriptions and sizes of the major heat transport and power generation components. Component configuration and sizing are based upon early phase AHTR plant thermal hydraulic models. The report also provides a top-down AHTR comparative economic analysis. A commercially available advanced supercritical water-based power cycle was selected as the baseline AHTR power generation cycle both due to its superior performance and to enable more realistic economic analysis. The AHTR system design, however, has several remaining gaps, and the plant cost estimates consequently have substantial remaining uncertainty. For example, the enriched lithium required for the primary coolant cannot currently be produced on the required scale at reasonable cost, and the necessary core structural ceramics do not currently exist in a nuclear power qualified form. The report begins with an overview of the current, early phase, design of the AHTR plant. Only a limited amount of information is included about the core and vessel as the core design and refueling options are the subject of a companion report. The general layout of an AHTR system and site showing the relationship of the major facilities is then provided. Next is a comparative evaluation of the AHTR anticipated performance and costs. Finally, the major system design efforts necessary to bring the AHTR design to a pre-conceptual level are then presented