20 Matching Results

Search Results

Advanced search parameters have been applied.

Contribution towards statistical intercomparison of general circulation models

Description: The Atmospheric Model Intercomparison Project (AMIP) of the World Climate Research Programme`s Working Group on Numerical Experimentation (WGNE) is an ambitious attempt to comprehensively intercompare atmospheric General Circulation Models (GCMs). The participants in AMIP simulate the global atmosphere for the decade 1979 to 1988 using, a common solar constant and Carbon Dioxide(CO{sub 2}) concentration and a common monthly averaged sea surface temperature (SST) and sea ice data set. In this work we attempt to present a statistical framework to address the difficult task of model intercomparison and verification.
Date: June 1, 1995
Creator: Sengupta, S. & Boyle, J.
Partner: UNT Libraries Government Documents Department

Nonlinear principal component analysis of climate data

Description: This paper presents the details of the nonlinear principal component analysis of climate data. Topic discussed include: connection with principal component analysis; network architecture; analysis of the standard routine (PRINC); and results.
Date: June 1, 1995
Creator: Boyle, J. & Sengupta, S.
Partner: UNT Libraries Government Documents Department

The NSTX Trouble Reporting System

Description: An online Trouble Reporting System (TRS) has been introduced at the National Spherical Torus Experiment (NSTX). The TRS is used by NSTX operators to report problems that affect NSTX operations. The purpose of the TRS is to enhance NSTX reliability and maintainability by identifying components, occurrences, and trends that contribute to machine downtime. All NSTX personnel have access to the TRS. The user interface is via a web browser, such as Netscape or Internet Explorer. This web-based feature permits any X-terminal, PC, or MAC access to the TRS. The TRS is based upon a trouble reporting system developed at the DIII-D Tokamak, at General Atomics Technologies. This paper will provide a detailed description of the TRS software architecture, user interface, MS SQL server interface and operational experiences. In addition, sample data from the TRS database will be summarized and presented.
Date: January 28, 2002
Creator: Sengupta, S. & Oliaro, G.
Partner: UNT Libraries Government Documents Department

Analysis of hyper-spectral data derived from an imaging Fourier transform: A statistical perspective

Description: Fourier transform spectrometers (FTS) using optical sensors are increasingly being used in various branches of science. Typically, a FTS generates a three-dimensional data cube with two spatial dimensions and one frequency/wavelength dimension. The number of frequency dimensions in such data cubes is generally very large, often in the hundreds, making data analytical procedures extremely complex. In the present report, the problem is viewed from a statistical perspective. A set of procedures based on the high degree of inter-channel correlation structure often present in such hyper-spectral data, has been identified and applied to an example data set of dimension 100 x 128 x 128 comprising 128 spectral bands. It is shown that in this case, the special eigen-structure of the correlation matrix has allowed the authors to extract just a few linear combinations of the channels (the significant principal vectors) that effectively contain almost all of the spectral information contained in the data set analyzed. This in turn, enables them to segment the objects in the given spatial frame using, in a parsimonious yet highly effective way, most of the information contained in the data set.
Date: January 10, 1996
Creator: Sengupta, S.K.; Clark, G.A. & Fields, D.J.
Partner: UNT Libraries Government Documents Department

Computer vision for detecting and quantifying gamma-ray sources in coded-aperture images

Description: The authors report the development of an automatic image analysis system that detects gamma-ray source regions in images obtained from a coded aperture, gamma-ray imager. The number of gamma sources in the image is not known prior to analysis. The system counts the number (K) of gamma sources detected in the image and estimates the lower bound for the probability that the number of sources in the image is K. The system consists of a two-stage pattern classification scheme in which the Probabilistic Neural Network is used in the supervised learning mode. The algorithms were developed and tested using real gamma-ray images from controlled experiments in which the number and location of depleted uranium source disks in the scene are known.
Date: November 2, 1994
Creator: Schaich, P.C.; Clark, G.A.; Sengupta, S.K. & Ziock, K.P.
Partner: UNT Libraries Government Documents Department

Remote secure proof of identity using biometrics

Description: Biometric measurements derived from finger- or voiceprints, hand geometry, retinal vessel pattern and iris texture characteristics etc. can be identifiers of individuals. In each case, the measurements can be coded into a statistically unique bit-string for each individual. While in electronic commerce and other electronic transactions the proof of identity of an individual is provided by the use of either public key cryptography or biometric data, more secure applications can be achieved by employing both. However the former requires the use of exact bit patterns. An error correction procedure allows us to successfully combine the use of both to provide a general procedure for remote secure proof of identity using a generic biometric device. One such procedure has been demonstrated using a device based on hand geometry.
Date: June 10, 1997
Creator: Sengupta, S. K.; Pearson, P. & Strait, R.S.
Partner: UNT Libraries Government Documents Department

Upgrade to the Tritium Remote Control and Monitoring System for TFTR D and D

Description: Since 1988, the Tritium Remote Control and Monitoring System (TRECAMS) has performed crucial functions in support of D-T [deuterium-tritium] operations of the Tokamak Fusion Test Reactor (TFTR) at the Princeton Plasma Physics Laboratory (PPPL). Although plasma operations on TFTR were completed in 1997, the need for TRECAMS continued. During this period TRECAMS supported the TFTR tritium systems, the TFTR's Shutdown and Safing phase, and the TFTR Decontamination and Decommissioning (D and D) project. The most critical function of the TRECAMS in the post-TFTR era has been to provide a real-time indication of the airborne tritium levels in the tritium areas and the (HVAC) stacks. TRECAMS is a critical tool in conducting safe TFTR D and D tritium-line breaks and other tritium-related work activities. Beginning in 1998, the failure rate of the system's hardware sharply increased. Furthermore, the specialized knowledge required to maintain the original software and hardware was diminishing. It soon became apparent that a failure of the TRECAMS could significantly impact the TFTR D and D project's cost and schedule. To preclude this, the TRECAMS hardware and software was upgraded in the year 2000 to use modern components. This paper will describe that successful upgrade, including a review of the engineering processes and our operating experiences with the upgraded system.
Date: January 28, 2002
Creator: Sichta, P.; Oliaro, G. & Sengupta, S.
Partner: UNT Libraries Government Documents Department

Fabrication of large domain YBa{sub 2}Cu{sub 3}O{sub x} for magnetic suspension applications

Description: Large domain YBa{sub 2}Cu{sub 3}O{sub x} levitators have been fabricated using a seeded melt processing technique. Depending upon the seed, either a single or five domained sample can be obtained. The grain boundaries separating each domains in the five domain levitator are found to be 90 degrees. Similar levitation forces can be observed for single and five domained samples. After thermal cycling, however, a small decrease in the levitation force of the five domain levitator was observed as a function of thermal cycles while nearly no change in force was observed in the single domain levitator. Finally it is shown that both, single and five domain YBCO, behave similarly as a function of sample thickness.
Date: December 31, 1995
Creator: Todt, V.R.; Zhang, X.; Miller, D.J.; Sengupta, S.; Corpus, J. & Gains, J.R. Jr.
Partner: UNT Libraries Government Documents Department

Pilot test of ANSI draft standard N13.29 environmental dosimetry -- Performance criteria for testing

Description: American National Standards Institute Draft N13.29 describes performance tests for environmental radiation dosimetry providers. If approved it would be the first step toward applying the types of performance testing now required in personnel dosimetry to environmental radiation monitoring. The objective of this study was to pilot test the draft standard, before it undergoes final balloting, on a small group of dosimetry providers that were selected to provide a mix of facility types, thermoluminescent dosimeter designs and monitoring program applications. The first phase of the pilot test involved exposing dosimeters to laboratory photon, beta, and x-ray sources at routine and accident dose levels. In the second phase, dosimeters were subjected to ninety days of simulated environmental conditions in an environmental chamber that cycled through extremes of temperature and humidity. Two out of seven participants passed all categories of the laboratory testing phase, and all seven passed the environmental test phase. While some relatively minor deficiencies were uncovered in the course of the pilot test, the results show that draft N13.29 describes useful tests that could be appropriate for environmental dosimetry providers. An appendix to this report contains recommendations that should be addressed by the N13.29 working group before draft N13.29 is submitted for balloting.
Date: September 1, 1998
Creator: Klemic, G.; Shebell, P.; Monetti, M.; Raccah, F.; Shobe, J.; Lamperti, P. et al.
Partner: UNT Libraries Government Documents Department

Updated flux information for neutron scattering and irradiation facilities at the BNL High Flux Beam Reactor

Description: The HFBR is a heavy water, D{sub 2}O, cooled and moderated reactor with twenty-eight fuel elements containing a maximum of 9.8 kilograms of {sup 235}U. While most reactors attempt to minimize the escape of neutrons from the core, the HFBR`s D{sub 2}O design allows the thermal neutron flux to peak in the reflector region and maximizes the number of thermal neutrons available to nine horizontal external beams, H-1 to H-9, used for neutron scattering and capture reactions, supporting physics, chemistry and biology experiments. All horizontal beam tubes were built tangential to the direction of the emerging neutrons, except for the H-2 beam tube, which looks directly at the core and has been used for neutron cross section measurements utilizing fast neutrons and for the TRISTAN fission product studies. In recent years, there have been some beam modifications and new instrumentation introduced at the HFBR. A high resolution neutron powder diffractometer instrument is now operating with a resolution of 5 {times} 10{sup {minus}4} at horizontal beam line H-1. To study scattering from liquid surfaces, a neutron reflection spectrometer was introduced on the CNF beam line at H-9. In the past year, a fourth beam line has been added to the CNF line at H-9. The existing beam plug at the H-6 beam line has recently been removed and a new plug, which will feature super mirrored surfaces, is now being installed. Last year, the vertical beam thimble, V-13, a fixed port filled with thirty year old samples used for HFBR material surveillance studies was replaced by a new thimble and charging station at the core edge creating an irradiation facility to substitute for the original V-13. A neutron dosimetry program has begun to measure and calculate the energy dependent neutron and gamma ray flux densities and/or dose rates at horizontal beam ...
Date: August 1997
Creator: Holden, N. E.; Hu, J. P.; Reciniello, R. N.; Sengupta, S.; Greenwood, L. R. & Farrell, K.
Partner: UNT Libraries Government Documents Department

Melt-texturing of carbon containing YBa{sub 2}Cu{sub 3}O{sub 7-x}: Influence of processing parameters on microstructure and flux-pinning behavior

Description: A detailed study of the flux-pinning behavior of sintered and melt-textured YBa{sub 2}Cu{sub 3}O{sub 7-x} has been carried out by means of microstructural investigations (optical microscopy, SEM, TEM, EDS, DTA, and XRD) and magnetization measurements. It was found that both microstructure and magnetization behavior strongly depend on the starting material, the production method, and the maximum processing temperature. In our experiments, the critical current density, J{sub c}, increased with increasing processing temperature between 920{degrees}C and 1050{degrees}C (25 - 130 emu/cm{sup 3}), but those samples processed at temperatures just above the peritectic transformation point (1020 OC and 1030 OC) exhibited a decreased J{sub c}. The carbon content of the starting powder and the powder`s melting behavior seem to play an important role in the development of microstructure and flux-pinning behavior during melt-texturing. A comparison of our data with previously published results shows that an optimized melt-texturing process can result in materials with critical current densities comparable to those of samples produced by Quench-Melt Growth.
Date: January 1, 1994
Creator: Todt, V.R.; Sengupta, S.; Chen, Y.L.; Shi, Donglu; Poeppel, R.; McGinn, P.J. et al.
Partner: UNT Libraries Government Documents Department

Land mine detection using multispectral image fusion

Description: Our system fuses information contained in registered images from multiple sensors to reduce the effects of clutter and improve the ability to detect surface and buried land mines. The sensor suite currently consists of a camera that acquires images in six bands (400nm, 500nm, 600nm, 700nm, 800nm and 900nm). Past research has shown that it is extremely difficult to distinguish land mines from background clutter in images obtained from a single sensor. It is hypothesized, however, that information fused from a suite of various sensors is likely to provide better detection reliability, because the suite of sensors detects a variety of physical properties that are more separable in feature space. The materials surrounding the mines can include natural materials (soil, rocks, foliage, water, etc.) and some artifacts. We use a supervised learning pattern recognition approach to detecting the metal and plastic land mines. The overall process consists of four main parts: Preprocessing, feature extraction, feature selection, and classification. These parts are used in a two step process to classify a subimage. We extract features from the images, and use feature selection algorithms to select only the most important features according to their contribution to correct detections. This allows us to save computational complexity and determine which of the spectral bands add value to the detection system. The most important features from the various sensors are fused using a supervised learning pattern classifier (the probabilistic neural network). We present results of experiments to detect land mines from real data collected from an airborne platform, and evaluate the usefulness of fusing feature information from multiple spectral bands.
Date: March 29, 1995
Creator: Clark, G.A.; Sengupta, S.K.; Aimonetti, W.D.; Roeske, F.; Donetti, J.G.; Fields, D.J. et al.
Partner: UNT Libraries Government Documents Department

Multispectral image fusion for detecting land mines

Description: This report details a system which fuses information contained in registered images from multiple sensors to reduce the effects of clutter and improve the ability to detect surface and buried land mines. The sensor suite currently consists of a camera that acquires images in six bands (400nm, 500nm, 600nm, 700nm, 800nm and 900nm). Past research has shown that it is extremely difficult to distinguish land mines from background clutter in images obtained from a single sensor. It is hypothesized, however, that information fused from a suite of various sensors is likely to provide better detection reliability, because the suite of sensors detects a variety of physical properties that are more separable in feature space. The materials surrounding the mines can include natural materials (soil, rocks, foliage, water, etc.) and some artifacts.
Date: April 1, 1995
Creator: Clark, G.A.; Sengupta, S.K.; Aimonetti, W.D.; Roeske, F.; Donetti, J.G.; Fields, D.J. et al.
Partner: UNT Libraries Government Documents Department

A Peer Review of the Strategy for Characterizing Ransuranics and Technetium Contamination in Uranium Hexafluoride Tails Cylinders

Description: This document provides the findings from a peer review of the Oak Ridge National Laboratory (ORNL) Hightower 2000 study, which set forth a strategy for characterization of low levels of radioactive contaminants in depleted uranium hexafluoride (DUF{sub 6}) cylinders at the Oak Ridge, Paducah, and Portsmouth gaseous diffusion plants. The information from that study will be used in a DOE-issued request for proposal (RFP) for conversion services from the private sector, to assist vendors in reducing costs associated with contingencies relating to handling this DUF{sub 6} with elevated transuranics (TRUs) and technetium (Tc). The Hightower study developed a general strategy for DUF{sub 6} sampling and analysis in accordance with their task but also recommended the following courses of action: (a) Collect and analyze liquid samples from the two identified Paducah Gaseous Diffusion Plant (PGDP) feed cylinders, feed the DUF{sub 6} into the cascades, and conduct an analysis on the resulting heels by washing and analyzing the wash rinsate; (b) Characterize the cylinder coatings to determine the extent and levels of polychlorinated biphenyl (PCB) contamination; and (c) Verify the characterization of the cylinder inventory's compliance with Department of Transportation (DOT) regulations and the American Society of Mechanical Engineers (ASME) pressure vessel code In addition to the above recommendations, the study also concluded that additional characterization is not likely to result in lower bids by prospective vendors, and that direct sampling of many older tails cylinders may be impractical.
Date: September 1, 2000
Creator: Sengupta, S.K.; Randich, E.; Avci, H.I.; Steindler, M.J. & Brumburgh, G.P.
Partner: UNT Libraries Government Documents Department

Characterization and environmental studies of Pompano Beach anaerobic digestion facility. Annual report

Description: Municipal solid wastes contain numerous substances of potential environmental concern. While some understanding of the composition of raw municipal waste and its leachate products is available, no information regarding characteristics of solid, liquid and gaseous outputs from anaerobic digestion exists. If centralized anaerobic digestion plants are to be environmentally viable, the characteristics and environmental effects of effluents from these plants must be acceptable. The environmental concerns are particularly acute where ground water supplies are precariously low and the water table is high, South Florida is such a location. A characterization and environmental study was initiated by the Resource Recovery Group on August 1978. The specific objectives are: (1) systematic characterization of solid, liquid and gaseous inputs and outputs; (2) investigations of leaching characteristic of output solid and liquid effluents, and the transport of pollutants to and through ground water systems; and (3) analysis of environmental and process parameters to obtain causal relationships.
Date: August 1, 1980
Creator: Sengupta, S.; Gerrish, H. P.; Wong, K. F..; Nemerow, N.; Daly, E. L., Jr.; Farooq, S. et al.
Partner: UNT Libraries Government Documents Department

Properties of hot isostatically pressed Bi sub 2 Sr sub 1. 7 CaCu sub 2 O sub x

Description: Dense Bi{sub 2}Sr{sub 1.7}CaCu{sub 2}O{sub x} (2212) superconductor pellets were made by hot isostatic pressing in an inert atmosphere. The pellets exhibited a small amount of preferred orientation of the grains. The transport critical current density (J{sub c}) values were very low for all specimens. Dislocations, planar faults, and intergrowths of the Bi{sub 2}Sr{sub 2}CuO{sub x} phase, which were produced during the pressing, caused the intragranular J{sub c} to increase substantially. 10 refs.
Date: April 1, 1992
Creator: Nash, S. (Marquette Univ., Milwaukee, WI (United States)); Goretta, K.C.; Miller, D.J.; Biondo, A.C.; Shi, D.; Sengupta, S. et al.
Partner: UNT Libraries Government Documents Department

Fabrication and characterization of melt-processed YBCO

Description: Large domain YBCO are fabricated by using a melt processing technique for magnetic levitation applications. A Nd{sub 1+x}Ba{sub 2{minus}x}Cu{sub 3}O{sub y} seed is used to initiate grain growth and to control the orientation of YBCO grains. Samples as large as 2 inch have been fabricated by utilizing this method. Microstructural studies reveals two distinct regions in these levitators due to different growth mechanism along a/b and c axis. Some initial results on the mass production of these levitators are also reported.
Date: November 1996
Creator: Sengupta, S.; Corpus, J.; Gaines, J. R., Jr.; Todt, V. R.; Zhang, X. F.; Miller, D. J. et al.
Partner: UNT Libraries Government Documents Department

Grain boundary weak links in high- Tc superconductors

Description: The transport critical current density (Jc) for high-{Tc} thin films, bicrystals, and bulk ceramics is shown to be determined by magnetic field penetration into the grain boundaries. The gross grain orientations may not in all cases be an important factor in determining this penetration. The parameter ({lambda}{sub G}/{lambda}{sub J}){sup 2} can characterize the strength of the grain boundary coupling, which depends mainly on the crystal coherence and connectivity at the boundary area.
Date: April 1, 1992
Creator: Shi, D.; Sengupta, S.; Goretta, K.C.; Salem-Sugui, S. Jr. (Argonne National Lab., IL (United States)); Smith, M. & Lwin, Y.N. (Western Illinois Univ., Macomb, IL (United States). Dept. of Physics)
Partner: UNT Libraries Government Documents Department

Processing and properties of silver-clad Tl-Ba-Ca-Cu-O wires and tapes

Description: TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} and Tl{sub 2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} powders were synthesized, loaded into Ag tubes, and worked into wires and tapes by drawing and rolling. All processing outside of furnaces was in a dry-N{sub 2} glovebox. All heat treatments were performed in O{sub 2}. The Ag-clad wires fabricated from these powders exhibited onset of superconductivity at {approx}118 K and critical current densities at 77K of 2{times}10{sup 3} to 4{times}10{sup 3} A/cm{sup 2}.
Date: March 1, 1992
Creator: Goretta, K.C.; Wu, C.T.; Lanagan, M.T.; Boling, M.A.; Shi, D.; Miller, D.J. et al.
Partner: UNT Libraries Government Documents Department