A novel electrical-impedance tomography (EIT) diagnostic system, including hardware and software, has been developed and used to quantitatively measure material distributions in multiphase flows within electrically-conducting (i.e., industrially relevant or metal) vessels. The EIT system consists of energizing and measuring electronics and seven ring electrodes, which are equally spaced on a thin nonconducting rod that is inserted into the vessel. The vessel wall is grounded and serves as the ground electrode. Voltage-distribution measurements are used to numerically reconstruct the time-averaged impedance distribution within the vessel, from which the material distributions are inferred. Initial proof-of-concept and calibration was completed using a stationary solid-liquid mixture in a steel bench-top standpipe. The EIT system was then deployed in Sandia's pilot-scale slurry bubble-column reactor (SBCR) to measure material distributions of gas-liquid two-phase flows over a range of column pressures and superficial gas flow rates. These two-phase quantitative measurements were validated against an established gamma-densitometry tomography (GDT) diagnostic system, demonstrating agreement to within 0.05 volume fraction for most cases, with a maximum difference of 0.15 volume fraction. Next, the EIT system was combined with the GDT system to measure material distributions of gas-liquid-solid three-phase flows in Sandia's SBCR for two different solids loadings. Accuracy for the three-phase flow measurements is estimated to be within 0.15 volume fraction. The stability of the energizing electronics, the effect of the rod on the surrounding flow field, and the unsteadiness of the liquid temperature all degrade measurement accuracy and need to be explored further. This work demonstrates that EIT may be used to perform quantitative measurements of material distributions in multiphase flows in metal vessels.
In this report we describe the performance of the ALEGRA shock wave physics code on a set of gas dynamic shock reflection problems that have associated experimental pressure data. These reflections cover three distinct regimes of oblique shock reflection in gas dynamics--regular, Mach, and double Mach reflection. For the selected data, the use of an ideal gas equation of state is appropriate, thus simplifying to a considerable degree the task of validating the shock wave computational capability of ALEGRA in the application regime of the experiments. We find good agreement of ALEGRA with reported experimental data for sufficient grid resolution. We discuss the experimental data, the nature and results of the corresponding ALEGRA calculations, and the implications of the presented experiment--calculation comparisons.
Sandia National Laboratories, New Mexico (SNL/NM) is a government-owned, contractor-operated facility overseen by the U.S. Department of Energy (DOE), National Nuclear Security Administration (NNSA) through the Albuquerque Operations Office (AL), Office of Kirtland Site Operations (OKSO). Sandia Corporation, a wholly-owned subsidiary of Lockheed Martin Corporation, operates SNL/NM. Work performed at SNL/NM is in support of the DOE and Sandia Corporation's mission to provide weapon component technology and hardware for the needs of the nation's security. Sandia Corporation also conducts fundamental research and development (R&D) to advance technology in energy research, computer science, waste management, microelectronics, materials science, and transportation safety for hazardous and nuclear components. In support of Sandia Corporation's mission, the Integrated Safety and Security (ISS) Center and the Environmental Restoration (ER) Project at SNL/NM have established extensive environmental programs to assist Sandia Corporation's line organizations in meeting all applicable local, state, and federal environmental regulations and DOE requirements. This annual report summarizes data and the compliance status of Sandia Corporation's environmental protection and monitoring programs through December 31, 2001. Major environmental programs include air quality, water quality, groundwater protection, terrestrial surveillance, waste management, pollution prevention (P2), environmental remediation, oil and chemical spill prevention, and the National Environmental Policy Act (NEPA). Environmental monitoring and surveillance programs are required by DOE Order 5400.1, General Environmental Protection Program (DOE 1990) and DOE Order 231.1, Environment, Safety, and Health Reporting (DOE 1996).
We present a set of novel design principles to aid in the development of complex collective behaviors in fleets of mobile robots. The key elements are: the use of a graph algorithm that we have created, with certain proven properties, that guarantee scalable local communications for fleets of arbitrary size; the use of artificial forces to simplify the design of motion control; the use of certain proximity values in the graph algorithm to simplify the sharing of robust navigation and sensor information among the robots. We describe these design elements and present a computer simulation that illustrates the behaviors readily achievable with these design tools.
Sandia Corporation (a subsidiary of Lockheed Martin Corporation through its contract with the U.S. Department of Energy [DOE]), National Nuclear Security Administration (NNSA) operates the Tonopah Test Range (TTR) in Nevada. Westinghouse Government Service, TTR's operations and maintenance contractor, performs most all environmental program functions. This Annual Site Environmental Report (ASER), which is published to inform the public about environmental conditions at TTR, describes environmental protection programs and summarizes the compliance status with major environmental laws and regulations during Calendar Year (CY) 2001.
The National Nuclear Security Administration is creating a ''Knowledge Base'' to store technical information to support the United States nuclear explosion monitoring mission. This guide is intended to be used by researchers who wish to contribute their work to the ''Knowledge Base''. It provides de.nitions of the kinds of data sets or research products in the ''Knowledge Base'', acceptable data formats, and templates to complete to facilitate the documentation necessary for the ''Knowledge Base''.
The process of developing the National Nuclear Security Administration (NNSA) Knowledge Base (KB) must result in high-quality Information Products in order to support activities for monitoring nuclear explosions consistent with United States treaty and testing moratoria monitoring missions. The validation, verification, and management of the Information Products is critical to successful scientific integration, and hence, will enable high-quality deliveries to be made to the United States National Data Center (USNDC) at the Air Force Technical Applications Center (AFTAC). As an Information Product passes through the steps necessary to become part of a delivery to AFTAC, domain experts (including technical KB Working Groups that comprise NNSA and DOE laboratory staff and the customer) will provide coordination and validation, where validation is the determination of relevance and scientific quality. Verification is the check for completeness and correctness, and will be performed by both the Knowledge Base Integrator and the Scientific Integrator with support from the Contributor providing two levels of testing to assure content integrity and performance. The Information Products and their contained data sets will be systematically tracked through the integration portion of their life cycle. The integration process, based on lessons learned during its initial implementations, is presented in this report.
The Navruz Project is a cooperative, transboundary, river monitoring project involving rivers and institutions in Kazakhstan, Kyrgyzstan, Tajikistan, and Uzbekistan facilitated by Sandia National Laboratories in the U.S. The Navruz Project focuses on waterborne radionuclides and metals because of their importance to public health and nuclear materials proliferation concerns in the region. Data obtained in this project are shared among all participating countries and the public through an internet web site and are available for use in further studies and in regional transboundary water resource management efforts. Overall, the project addresses three main goals: to help increase capabilities in Central Asian nations for sustainable water resources management; to provide a scientific basis for supporting nuclear transparency and non-proliferation in the region; and to help reduce the threat of conflict in Central Asia over water resources, proliferation concerns, or other factors. The Navruz project has a duration of three years. This document contains the reports from each of the participating institutions following the first year of data collection. While a majority of samples from the Navruz project are within normal limits, a preliminary analysis does indicate a high concentration of selenium in the Kazakhstan samples. Uzbekistan samples contain high uranium and thorium concentrations, as well as elevated levels of chromium, antimony and cesium. Additionally, elevated concentrations of radioactive isotopes have been detected at one Tajikistan sampling location. Further analysis will be published in a subsequent report.
The Entero Software Project emphasizes flexibility, integration and scalability in modeling complex engineering systems. The GUIGenerator project supports the Entero environment by providing a user-friendly graphical representation of systems, mutable at runtime. The first phase requires formal language specification describing the syntax and semantics of extensible Markup Language (XML) elements to he utilized, depicted through an XML schema. Given a system, front end user interaction with stored system data occurs through Java Graphical User Interfaces (GUIs), where often only subsets of system data require user input. The second phase demands interpreting well-formed XML documents into predefined graphical components, including the addition of fixed components not represented in systems such as buttons. The conversion process utilizes the critical features of JDOM, a Java based XML parser, and Core Java Reflection, an advanced Java feature that generates objects at runtime using XML input data. Finally, a searching mechanism provides the capability of referencing specific system components through a combination of established search engine techniques and regular expressions, useful for altering visual properties of output. The GUIGenerator will be used to create user interfaces for the Entero environment's code coupling in support of the ASCI Hostile Environments Level 2 milestones in 2003.
Imaging systems such as Synthetic Aperture Radar collect band-limited data from which an image of a target scene is rendered. The band-limited nature of the data generates sidelobes, or ''spilled energy'' most evident in the neighborhood of bright point-like objects. It is generally considered desirable to minimize these sidelobes, even at the expense of some generally small increase in system bandwidth. This is accomplished by shaping the spectrum with window functions prior to inversion or transformation into an image. A window function that minimizes sidelobe energy can be constructed based on prolate spheroidal wave functions. A parametric design procedure allows doing so even with constraints on allowable increases in system bandwidth. This approach is extended to accommodate spectral notches or holes, although the guaranteed minimum sidelobe energy can be quite high in this case. Interestingly, for a fixed bandwidth, the minimum-mean-squared-error image rendering of a target scene is achieved with no windowing at all (rectangular or boxcar window).
The Zone 4 Stage Right Shielded Lift Trucks (SLT's) will likely need refurbishment or replacement within the next two to five years, due to wear. This document discusses the options to provide a long term and reliable means of satisfying Zone 4 material movement and inventory requirements.
The National Nuclear Security Administration is creating a Knowledge Base to store technical information to support the United States nuclear explosion monitoring mission. This document defines the core database tables that are used in the Knowledge Base. The purpose of this document is to present the ORACLE database tables in the NNSA Knowledge Base that on modifications to the CSS3.0 Database Schema developed in 1990. (Anderson et al., 1990). These modifications include additional columns to the affiliation table, an increase in the internal ORACLE format from 8 integers to 9 integers for thirteen IDs, and new primary and unique key definitions for six tables. It is intended to be used as a reference by researchers inside and outside of NNSA/DOE as they compile information to submit to the NNSA Knowledge Base. These ''core'' tables are separated into two groups. The Primary tables are dynamic and consist of information that can be used in automatic and interactive processing (e.g. arrivals, locations). The Lookup tables change infrequently and are used for auxiliary information used by the processing. In general, the information stored in the core tables consists of: arrivals; events, origins, associations of arrivals; magnitude information; station information (networks, site descriptions, instrument responses); pointers to waveform data; and comments pertaining to the information. This document is divided into four sections, the first being this introduction. Section two defines the sixteen tables that make up the core tables of the NNSA Knowledge Base database. Both internal (ORACLE) and external formats for the attributes are defined, along with a short description of each attribute. In addition, the primary, unique and foreign keys are defined. Section three of the document shows the relationships between the different tables by using entity-relationship diagrams. The last section, defines the columns or attributes of the various tables. Information that is included is the Not Applicable (NA) value, the format of the data and the applicable range for the attribute.
The authors present a VHDL design that incorporates optimizations intended to provide digital signature generation with as little power, space, and time as possible. These three primary objectives of power, size, and speed must be balanced along with other important goals, including flexibility of the hardware and ease of use. The highest-level function doffered by their hardware design is Elliptic Curve Optimal El Gamal digital signature generation. The parameters are defined over the finite field GF(2{sup 178}), which gives security that is roughly equivalent to that provided by 1500-bit RSA signatures. The optimizations include using the point-halving algorithm for elliptic curves, field towers to speed up the finite field arithmetic in general, and further enhancements of basic finite field arithmetic operations. The result is a synthesized VHDL digital signature design (using a CMOS 0.5{micro}m, 5V, 25 C library) of 191,000 gates that generates a signature in 4.4 ms at 20 MHz.
This paper is the latest in a series of papers that attempt to relate the multiple observed gas breakdown phenomena to useful switch design parameters. This series started when the as density, not the gas type, was observed to give a power law relationship for the breakdown delay time delays of several gases to the applied electric field. This paper will show that this triggering or breakdown initiating process is similar to, if not the same as, a corona discharge. A hypothesis is made and a simple voltage breakdown relationship is shown to exist for air gaps between 1 and 1000 cm for sharp electrodes to a plane.
Specially designed synchronous ac generators can provide a high energy pulse power source capable of supplying energy to various pulse forming networks. One such generator, which is the subject of this paper, is presently being used as the prime power source for the Repetitive High Energy Pulsed Power Module (RHEPP) at Sandia National Laboratories. The generator has been designed to operate continuously in two distinct modes. In the first mode the generator can supply 50-kJ, 9.5-kV, 11,000-amp, 1-msec pulses continuously (500 kW average power) with a rep rate from 1 to 10 Hs. In the second mode, 20.8-kJ, 9.5-kV, 1052-amp, 4-msec pulses can be supplied continuously (5000 kW average power) at a rep rate of 240 pulses per second. The latter mode is being used in the RHEPP application at a reduced energy and voltage level. The generator was successfully tested in 9/89 to verify the performance at its maximum rating. Test results are presented along with details of the generator design and its applications.
Microwave two-port S-parameter measurements and modeling were performed on superconducting flux flow transistors. These transistors, based on the magnetic control of flux flow in an array of high-temperature superconducting weak links, can exhibit significant available power gain at microwave frequencies (over 20 dB at 7-10 GHz in some devices). The input impedance is largely inductive, while the output impedance is resistive and inductive. These devices are potentially useful in numerous applications, including matched amplifiers.< >
Pulse transformer conceptual design and system studies were conducted at the Westinghouse Science and Technology Center for the Sandia National Laboratories' Repetitive High Energy Pulsed Power (RHEPP) System. The RHEPP system relies on magnetic switches to achieve pulse compression from 120 Hz ac to microsecond pulses. A 600 kW, 120 Hz Westinghouse alternator supplies ac prime power at 10 kV (rms). Two magnetic switching stages will compress the pulses to 115 usec prior to the pulse transformer. The transformer steps the voltage up to 254 kV. The pulse transformer has an 18:1 turns ratio and is capable of continuous duty operation. System studies were conducted to minimize transformer loss and leakage inductance within transformer size constraints. The optimized design had a 3-step nickel iron core with 9 primary turns.
Flash x-ray sources at Sandia National Laboratories routinely test the hardness of electronic components to simulated threat spectra. While it is traditional to calculate the x-ray spectra produced in a given exposure from measurements of free-field dose, current, and voltage, these experimental quantities may not be accurately known for some source geometries. It is appropriate, therefore, to include a direct measurement of the x-ray spectrum for such tests. Random error propagation and unfold accuracy have been studied for the spectral unfold method used in the x-ray absorption spectrometer reported by Carlson. This system of 13 measurements and 30 spectral bins (0.01 -- 8 MeV) is underdetermined; a trial spectrum prevents unphysical solutions. Accuracy of the unfold was tested with simulated data from known spectra; the unfolds agreed with the known spectra to better than 10%, between 0.05 MeV and near the endpoints. Error propagation was studied by perturbing the input data randomly and unfolding the resulting data sets. In each unfold energy bin the standard deviation was taken as the propagated error. Above 0.05 MeV the unfold roughly doubled the input errors. The trail spectrum affects the unfold accuracy more strongly than the propagated errors.