| Comprehensive Nuclear-Test-Ban Treaty: Updated 'Safeguards' and Net Assessments |
03-Jun-2009 |
|
| Authors:
Jonathan Medalia; LIBRARY OF CONGRESS WASHINGTON DC CONGRESSIONAL RESEARCH SERVICE
|
 | Limitations on nuclear testing have been on the international agenda since 1954. The United States ratified one such treaty in 1963 and two in 1990 that together bar all but underground nuclear tests with an explosive yield of 150 kilotons or less. The United States has observed a unilateral moratorium on nuclear tests since 1992. In 1996, this nation signed the Comprehensive Nuclear-Test-Ban Treaty (CTBT), which would ban all nuclear ... |
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| Frequency Dependence of Q in the Crust and Upper Mantle of China and Surrounding Regions, from Computations of Lg Q and the Attenuation of High-Frequency P-Waves |
MAY 2006 |
45 pages |
| Authors:
B. J. Mitchell; A. L. Jemberie; F. Leyton; R. Chu; A. Fatehi; SAINT LOUIS UNIV MO DEPT OF EARTH AND ATMOSPHERIC SCIENCES
|
 | Starting with fundamental-mode Rayleigh-wave attenuation coefficient values predicted by previously determined frequency-independent model of shear-wave Q we have obtained frequency-dependent Q models that explain both the measured values of yr as well as of Lg coda Q and its frequency dependence at 1 Hz (Q and n respectively) for China and some adjacent regions. The process combines trial-and-error selection of a model for the depth distribution of the frequency parameter ... |
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| The Use of Hydroacoustic Phases for the Detection of Oceanic Events: Observations and Numerical Modeling |
JUL 2004 |
63 pages |
| Authors:
Catherine DE Groot-Hedlin; Donna Blackman; John Orcutt; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA
|
| Hydroacoustic monitoring of the Comprehensive Nuclear Test Ban Treaty (CTBT) requires the ability to detect and locate phenomena that give rise to acoustic signals. An improved understanding of the coupling of seismic energy to acoustic energy is necessary to improve location estimates of earthquakes and volcanic eruptions. Using known variations in near-source bathymetry, the authors demonstrated that scattering of seismic to acoustic energy at a rough seafloor yields the approximate ... |
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| Discrimination, Detection, Depth, Location, and Wave Propagation Studies Using Intermediate Period Surface Waves in the Middles East, Central Asia, and the Far East |
JUL 2003 |
152 pages |
| Authors:
Anatoli L. Levshin; Michael H. Ritzwoller; COLORADO UNIV AT BOULDER DEPT OF PHYSICS
|
| The objective of this research was to construct surface wave group velocity maps at intermediate periods for the Near East, Central Asia and the Far East and to estimate the possibility of using these maps to extract weak surface wave signals and measure their amplitude spectra. To reach these goals we acquired broadband digital records of more than 1600 events that occurred in and around Eurasia during the period 1976-1998 ... |
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| Technical Operations Division - Heritage Remembered |
09 APR 1999 |
124 pages |
| Authors:
AIR FORCE TECHNICAL APPLICATIONS CENTERPATRICK AFB FL
|
| The Technical Operations Division (TOD) at McClellan Air Force Base will be inactivated on 30 September 1999 after nearly 50 years of vigilance over the nuclear world. TOD was the largest subordinate unit of the Air Force Technical Applications Center, (AFTAC), headquartered at Patrick Air Force Base, Florida. AFTAC is responsible for monitoring several nuclear testing treaties by detecting and identifying nuclear explosions, anywhere on or in the planet. As ... |
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| High Frequency 3-Component Waveform Inversion for Source and Structural Parameters |
01 SEP 1998 |
57 pages |
| Authors:
Danny J. Harvey; Anatoli L. Lavehio; COLORADO UNIV AT BOULDER DEPT OF PHYSICS
|
| We present the results of three studies to develop and verify techniques to classify weak seismic events. (1) The method and results of full waveform inversion for both detailed source parameters and structure parameters are described. Input data were seismograms from industrial explosions in Eastern Kazakhstan recorded by the NRDC seismic network in 1987. Very good fits were produced between the synthetic seismograms and the observed data on all three ... |
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| Special Event Discrimination Analysis: The TEXAR Blind Test and Identification of the August 16, 1997 Kara Sea Event |
31 MAR 1998 |
78 pages |
| Authors:
Douglas Baumgardt; ENSCO INC SPRINGFIELD VA
|
| The International Monitoring System (IMS) for the Comprehensive Test Ban Treaty (CTBT) faces the serious challenge of being able to accurately and reliably identify seismic events in any region of the world. Extensive research has been performed in recent years on developing discrimination techniques which appear to classify seismic events into broad categories of source types, such as nuclear explosion, earthquake, and mine blast. This report examines ... |
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| A Fifty Year Commemorative History of Long Range Detection: The Creation, Development, and Operation of the United States Atomic Energy Detection System |
SEP 97 |
|
| Authors:
SCIENCE APPLICATIONS INTERNATIONAL CORP SATELLITE BEACH FL
|
| This document publicly commemorates the art and science of 50 years of US Long Range Detection (LRD). LRD is the technical ability to detect, locate, and identify nuclear explosions occurring at remote distances on (or under) the surface of the earth, under its oceans, in its atmosphere, or deep in outer space. |
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| Broadband Seismology and the Detection and Verification of Underground Nuclear Explosions |
31 JAN 97 |
69 pages |
| Authors:
Mark A. Tinker; ARIZONA UNIV TUCSON DEPT OF GEOSCIENCES
|
| The detection and identification of low yield explosions requires seismic stations at regional distances. However, because the regional wavefield propagates within the extremely heterogeneous crustal waveguide, the seismic waveforms are also very complicated. Therefore, it is necessary to have a solid understanding of how the phases used in regional discriminants develop within different tectonic regimes. Thus, the development of the seismic phases Pn and Lg, which compose the seismic discriminant ... |
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| Physical Mechanisms of Quarry Blast Sources |
JAN 97 |
52 pages |
| Authors:
T. G. Barker; K. L. McLaughlin; J. Bonner; MAXWELL TECHNOLOGIES INC SAN DIEGO CA FEDERAL DIV
|
| Models of quarry blasts may serve to develop efficient and robust methods for discriminating quarry blasts from other sources. In this report, we present progress on modeling quarry blasts at the Chemline quarry in central Texas and the Black Thunder mine in the Powder River Basin of Wyoming. We observe strong variations in near field ground motions at the Black Thunder mine. Using estimates of site response derived from signal ... |
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| Surface Topography Effects on Lg Wave Propagation in Heterogeneous Crustal Waveguides |
JAN 97 |
35 pages |
| Authors:
R. Wu; T. Lay; X. Xie; X. Chen; PHILLIPS LAB HANSCOM AFB MA
|
| The object of this research is to study the effects of surface topography, near surface (sedimentary) structure and the associated small scale heterogeneities on regional wave propagation which is critical for both discrimination and yield estimation in monitoring a Comprehensive Test Ban Treaty and the current Nuclear Non-Proliferation Treaty. We aim at developing a hybrid method which couples the recently developed fast screen propagator theory and methods (Wu, 1994; Wu ... |
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| Source Functions of Nuclear Explosions from Spectral Synthesis and Inversion |
20 NOV 96 |
32 pages |
| Authors:
Peter Puster; Thomas H. Jordan; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| We apply methods for the recovery of the frequency dependent moment rate tensor, M(w), to the study of Lop Nor nuclear explosions. This approach encompasses many source parameter diagnostics that have been traditionally used to discriminate nuclear explosions from chemical explosions and earthquakes and has the potential to provide new discrimination tools. We parameterize the source as M(w) = M1(a)) + MD(a)), where M1(co) and MD((O) are isotropic and deviatoric ... |
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| Investigation of Lg Blockage and the Transportability of Regional Discriminants in the Middle East |
NOV 96 |
85 pages |
| Authors:
Douglas Baumgardt; ENSCO INC SPRINGFIELD VA
|
| To investigate nuclear explosion monitoring in the Middle East, the characteristics of regional phase propagation and regional discriminants have been investigated for events and propagation paths in Israel, Jordan, Lebanon, Syria, Egypt, and Iran. Mostly earthquake recordings from stations in the Middle East, including Iranian Long Period Array (ILPA) and Mednet and IRIS stations, have been studied with the goal of relating regional characterization of events in the Middle East ... |
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| Infrasound and the Infrasonic Monitoring or Atmospheric Nuclear Explosions: An Annotated Bibliography |
31 OCT 96 |
155 pages |
| Authors:
J. M. McKisic; TRACOR APPLIED SCIENCES INC ROCKVILLE MD
|
| This report presents an annotated and unclassified bibliography of selected references from refereed and other literature sources which are deemed relevant to those governmental, industry and academic institutions interested in the technical aspects of infrasound, in general, and in the particular use of infrasound to monitor compliance within the context of a comprehensive nuclear test ban treaty (CTBT). The review covers papers published during the time period extending from 1874 ... |
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| Research on Seismic Monitoring at Regional Distances |
15 OCT 96 |
87 pages |
| Authors:
Wenjie Dong; Richard L. Gibson Jr.; Matthias G. Imhof; M. N. Toksoez; MASSACHUSETTS INST OF TECH CAMBRIDGE EARTH RESOURCES LAB
|
| We report two studies related to numerical modeling of seismic wave generation and propagation. In the first, numerical calculations of seismic wave scattering using the multiple multipole technique are compared to laboratory data that we collected in an ultrasonic experiment. The results demonstrate the validity of the multiple multipole approach for seismic wave propagation modeling. The second study investigates seismic radiation from explosively loaded cavities in isotropic and transversely isotropic ... |
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| Development of a Comprehensive Hydroacoustic Coverage Assessment Model |
SEP 96 |
76 pages |
| Authors:
Ted Farrell; Kevin LePage; BBN SYSTEMS AND TECHNOLOGIES CORP ARLINGTON VA
|
| A model for predicting the detection and localization performance of hydroacoustic monitoring networks has been developed. The model accounts for major factors affecting global-scale acoustic propagation in the ocean, such as horizontal refraction from bathymetric features and horizontal changes in sound speed, travel time variability due to spatial and temporal fluctuations in the ocean, and detailed characteristics of the source. In this report, a summary description of the component submodels, ... |
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| Report on Phase Blockage Phenomenology Session, SSA 91st Annual Meeting, 2 April 1996, St. Louis, Missouri |
05 JUN 96 |
27 pages |
| Authors:
Delaine T. Reiter; Rong-Song Jih; PHILLIPS LAB HANSCOM AFB MA
|
| This report details the results of a special session on regional phase blockage which was held during the Seismological Society of America's 91st Annual Meeting in St. Louis, Missouri on April 2, 1996. The session consisted of seven orally presented papers by members of the seismic monitoring research community and a follow-up meeting that was intended to be a discussion session about the scientific problem of phase blockage. The report ... |
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| Cemented Particulate Materials: From Grain-to-Grain Contact to Macro- Behavior |
20 APR 96 |
113 pages |
| Authors:
Jack Dvorkin; STANFORD UNIV CA DEPT OF GEOPHYSICS
|
| The overall objective of the proposed research was to provide a quantitative description of the microstructural, as well as macroscopic mechanical behavior of particulate materials with intergranular cementation in a wide range of strain amplitudes and for various types of the cementation material. By cementation, a material is meant which fills the space between two surfaces that are (a) separated or (b) contact directly. This objective was achieved by deriving ... |
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| Nuclear Monitoring Research and Development Project |
MAR 96 |
|
| Authors:
Thomas J. Sereno Jr; SCIENCE APPLICATIONS INTERNATIONAL CORP SAN DIEGO CA
|
| This is the final report for the Nuclear Monitoring Research and Development (NMRD) Project covering the period November 1991 through March 1996. This project is a follow on to a previous project to develop the next generation system for nuclear explosion monitoring called the Intelligent Monitoring System or IMS (Bache et aL, 1993). The IMS consists of automated and interactive systems to detect, locate and identify seismic events to facilitate ... |
|
| 'On Detecting Outliers in Mixed Populations' |
FEB 96 |
54 pages |
| Authors:
H. L. Gray; S. R. Sain; W. H. Frawley; W. A. Woodward; SOUTHERN METHODIST UNIV DALLAS TX DEPT OF STATISTICAL SCIENCE
|
| In this report we introduce an operational methodology for detecting outliers in data which is a mixture of events from a variety of sources. The only assumption required is that the data contain no previous nuclear events. Thus ground truth data is not required. The method models the data as a mixture of two or more event types. It then develops a test statistic based on a modified likelihood ratio ... |
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| A Simple, Causal Method to Incorporate Anelastic Attenuation into Finite-Difference Calculations |
21 DEC 95 |
58 pages |
| Authors:
Rong-Song Jih; PHILLIPS LAB HANSCOM AFB MA
|
| Current nuclear treaty monitoring interest has shifted to the verification of a comprehensive test ban treaty (CTBT), including the detection of the first test of potential proliferators. Predictive modeling capabilities are crucial, not just desirable, in the context of CTBT and proliferation monitoring. Synthetic seismograms generated with the linear-finite-difference (LFD) code are particularly useful for regions where earthquake or explosion data are not available. However, to date many LFD modeling ... |
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| Investigation of Ionospheric Disturbances and Associated Diagnostic Techniques |
12 DEC 95 |
21 pages |
| Authors:
L. M. Duncan; CLEMSON UNIV SC
|
| The objectives of this research and development program were to conduct simulation modeling of the generation and propagation of atmospheric acoustic signals associated with surface and subsurface ground disturbances; to construct an experimental measurement system for exploratory research studies of acoustic generated ionospheric disturbances; to model high power radio wave propagation through the ionosphere, including nonlinear wave plasma interaction effects; and to assist in the assessment of diagnostic systems for ... |
|
| Calibration Studies at TXAR, |
14 AUG 1995 |
10 pages |
| Authors:
Ileana Tibuleac; Eugene Herrin; Paul Golden; SOUTHERN METHODIST UNIV DALLAS TX DEPT OF GEOLOGICAL SCIENCES
|
| This poster presents some of the results of calibration studies at TXAR. Well over 100 regional and teleseismic events that were located by the USGS were used in this study. A time domain correlation method was used to process the TXAR data and obtain estimates of phase velocity and back azimuth for these events. A magnitude scale and an azimuth correction table was then constructed for TXAR. |
|
| Case Studies of Seismic Discrimination Problems and Regional Discriminant Transportability |
31 JUL 95 |
87 pages |
| Authors:
Douglas R. Baumgardt; ENSCO INC SPRINGFIELD VA SIGNAL ANALYSIS SYSTEMS DIV
|
| This report describes case studies of regional seismic discriminants, using the Intelligent Seismic Event Identification System (ISEIS), and addresses issues related to the transportability of regional discriminants. Some of the key results of this study include: (1) Observations of large Lg waves from mine blasts. (2) Investigation of the P/S frequency-dependence discriminant. (3)The importance of signal decorrelation in the generation of spectral scalloping by ripple fired mine blasts. (4) Path ... |
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| Discriminating Underground Explosions from Earthquakes Using Seismic Coda Waves |
15 JAN 95 |
35 pages |
| Authors:
Keiiti Aki; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES CENTER FOR EARTH SCIENCES
|
| We successfully discriminated quarry blasts and earthquakes at local distance from the observed source power spectra by using the coda Q method. To extend this discrimination method to events at regional distances, we developed the energy transfer theory for a mixture of Rayleigh and S wave propagation in a random scattering and attenuation medium. Applying this theory to the quarry blast earthquake problem at local distance, we can explain the ... |
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| Analysis of 3D Complex Structure and Heterogeneity Effects on Formation and Propagation of Regional Phases in Eurasia |
13 DEC 94 |
66 pages |
| Authors:
Thorne Lay; Ru-Shan Wu; CALIFORNIA UNIV SANTA CRUZ INST OF TECTONICS
|
| This is the final report for this grant to develop new three- dimensional wave propagation techniques for high frequency waves in heterogeneous media. The report is divided into four sections, each being a published paper sponsored by this grant. In the first section we formulate a one-way wide-angle elastic wave propagation method for arbitrarily heterogeneous media in both the space and wavenumber domains using elastic Rayleigh integrals and local elastic ... |
|
| Semiannual Technical Summary, 1 April - 30 September 1994 (Royal Norwegian Council for Scientific and Industrial Research) |
NOV 94 |
136 pages |
| Authors:
ROYAL NORWEGIAN COUNCIL FOR SCIENTIFIC AND INDUSTRIAL RESEARCH KJELLER
|
| This Semiannual Technical Summary describes the operation, maintenance and research activities at the Norwegian Seismic Array (NORSAR), the Norwegian Regional Seismic Array (NORESS), the Arctic Regional Seismic Array (ARCESS) and the experimental Spitsbergen Regional Array for the period for the period 1 April - 30 September 1994. Statistics are also presented for additional seismic stations, which through cooperative agreements with institutions in the host countries provide continuous data to the ... |
|
| Design, Evaluation, and Construction of Texess and Luxess, and Research in Mini-Array Technology and use of Data from Single Stations and Sparse Networks. Phase 3 |
OCT 94 |
54 pages |
| Authors:
Eugene Herrin; Paul Golden; Herbert Robertson; SOUTHERN METHODIST UNIV DALLAS TX
|
| Objectives are : (1) conduct research in seismic mini-array technology and single stations and sparse networks data, (CLIN 1) and (2) design, evaluate, and construct TEXESS, in Southwest Texas, and LUXESS, northeast of Luxor, Egypt, (CLIN 2), along the lines of a GSE Alpha Station. TEXESS was installed by SMU personnel in August 1993, and the first event was a local recorded on 31 August. With deinstallation on hold awaiting ... |
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| Advanced Waveform Research Methods for GERESS Recordings. Monitoring Nuclear Test Sites with GERESS |
15 JUN 94 |
103 pages |
| Authors:
H. P. Harjes; M. Jost; J. Schweitzer; G. Bokelmann; BOCHUM UNIV (GERMANY F R)
|
| This report summarizes research activities with GERESS data carried out at the institute of Geophysics in Bochum during the second semiannual period (December 1993- May 1994) of the current grant. GERESS data are continuously transmitted from the array hub in Bavaria to Bochum and analyzed by an on-line processing system, based on RONAPP, to detect and locate seismic events in near real-time. The GERESS data centre in Bochum continued to ... |
|
| Advanced Waveform Research Methods for GERESS Recordings |
15 JUN 94 |
98 pages |
| Authors:
H. -p. Harjes; M. Jost; J. Schweitzer; G. Bokelmann; BOCHUM UNIV (GERMANY F R)
|
| Two major research projects were finished and separated papers are included in this report. The first paper (Jost et al) summarizes the GERESS recordings of underground nuclear explosions. Path-specific detection thresholds at GERESS are derived for NTS, Tuamotu Archipelago, Kazakhstan, Novaya Zemlya, and Lop Nor. These empirical detection thresholds substantially deviate from those calculated from global amplitude-distance relations (i.e. Gutenbergy- Richter). This case history again casts some doubts on theoretical ... |
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| Seismic Identification Analyses of Cavity Decoupled Nuclear and Chemical Explosions |
JAN 94 |
82 pages |
| Authors:
John R. Murphy; Brian W. Barker; S-CUBED LA JOLLA CA
|
| Successful seismic monitoring of any eventual Comprehensive Test Ban Treaty will require development of a capability to identify signals from small cavity decoupled nuclear explosions from among numerous signals to be expected from earthquakes, rockbursts and chemical explosion (CE) events of comparable magnitude. The investigations summarized in this report focus on preliminary studies which have been carried out in an attempt to distinguish between decoupled nuclear explosions and CE events ... |
|
| Arms Control and Nonproliferation Technologies, First Quarter 1994 |
94 |
|
| Authors:
DEPARTMENT OF ENERGY WASHINGTON DC OFFICE OF ARMS CONTROL AND NONPROLIFERATIO N
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| Advanced Discrimination Technology |
11 NOV 93 |
|
| Authors:
L. J. Burdick; D. V. Helmberger; C. K. Saikia; WOODWARD-CLYDE CONSULTANTS PASADENA CA
|
| In this era of increased concern for the proliferation of nuclear weapons, the need for effective seismic discrimination techniques is as important as ever. As more countries attain or near the technology threshold needed to develop nuclear weapons, more regions of the world need to be monitored for verification purposes. Many of these countries are within tectonically active environments, and since small magnitude events are too weak to be seen ... |
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| Proceedings of the Numerical Modeling for Underground Nuclear Test Monitoring Symposium Durango, Colorado March 23-25, 1993 |
NOV 93 |
|
| Authors:
Steven R. Taylor; James R. Kamm; CALIFORNIA UNIV LOS ANGELES DEPT OF ENERGY AND KINETICS
|
|
| Monitoring Earthquake and Explosion Sources in the Soviet Union |
30 SEP 93 |
50 pages |
| Authors:
Alan L. Kafka; Joseph I. Blaney; Allyn K. Bowers; Susan E. D'Annolfo; Matthew R. Jacobson-Carroll; WESTON OBSERVATORY MA
|
| This report describes the results of five research projects conducted at Weston Observatory under Contract No. F19628-90-K-0035. The research conducted under this contract covers a range of topics related to seismology in general and to nuclear test monitoring in particular. Details of the results of each project are described in the following five Scientific Reports: (1) Database Relations for Seismic Phases Reported by Stations in the Former Soviet Union. (2) ... |
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| Database Relations for Seismic Phases Reported by Stations in the Former Soviet Union |
30 SEP 93 |
60 pages |
| Authors:
A. L. Kafka; WESTON OBSERVATORY MA
|
| This report is one of five Scientific Reports describing specific research projects conducted at Weston Observatory under Contract No. F19628-90- K-0035. The research conducted under this contract covers a range of topics related to seismology in general and to nuclear test monitoring in particular. This Scientific Report (No. 5) describes a project in which computer software was developed to produce database relations for seismic phases reported by stations in the ... |
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| The Intelligent Monitoring System Extensions to the Center Version 3 Database. Revision 1 |
27 AUG 93 |
103 pages |
| Authors:
J. Anderson; T. J. Sereno Jr.; H. Swanger; J. Given; D. Williams; SCIENCE APPLICATIONS INTERNATIONAL CORP SAN DIEGO CA
|
| This technical report updates SAIC-91/1138, published February 1991. It describes the IMS extensions to the Center Version 3.0 database schema, documented in Technical Report C90-01 (Sept. 1990). This report briefly describes IMS pipeline processing and the application-specific tables designed to support this processing. |
|
| CenterView Version 2 Tutorial |
AUG 93 |
48 pages |
| Authors:
David Corley; Christine Ferraro; SCIENCE APPLICATIONS INTERNATIONAL CORP ARLINGTON VA CENTER FOR SEISMIC STUDI ES
|
| This report serves as a tutorial for Version 2 of the CenterView program, menu based interface to the Center for Seismic Studies Version 3.0 format databases. This report guides the user through several of the more common queries performed in CenterView. It contains an appendix that describes how to set up communications between CenterView and other programs at the Center for Seismic Studies. Seismology, Database management systems, Nuclear test detection ... |
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| Regional Characterization of Mine Blasts, Earthquakes, Mine Tremors, and Nuclear Explosions using the Intelligent Seismic Event Identification System |
31 JUL 93 |
99 pages |
| Authors:
Douglas R. Baumgardt; ENSCO INC SPRINGFIELD VA
|
| This report describes the results of a study of the Intelligent Seismic Event Identification System (ISEIS) which was installed at the Center for Seismic Studies and applied to regional events in the Intelligent Monitoring System (IMS) database. A subset of IMS data has been collected for known events in a database called the Ground Truth Database (GTD) and these events were processed by ISEIS. This has shown that the regional ... |
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| A Geological and Geophysical Information System for Eurasia |
29 JUN 93 |
16 pages |
| Authors:
Eric J. Fielding; Muawia Barazangi; Bryan L. Isacks; CORNELL UNIV ITHACA NY INST FOR THE STUDY OF THE CONTINENTS
|
| Topography and heterogeneous crustal structure have major effects on the propagation of regional seismic phases. We are collecting topographical, geological, and geophysical datasets for Eurasia into an information system that can be accessed via Internet connections. Now available are digital topography, satellite imagery, and data on sedimentary basins and crustal structure thicknesses. We are expanding the scope of our information system to include data on the Middle East and North ... |
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| Discrimination of Earthquakes and Explosions at Regional Distances Using Complexity |
17 JUN 93 |
|
| Authors:
Robert R. Blanford; AIR FORCE TECHNICAL APPLICATIONS CENTER PATRICK AFB FL
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| Computational Modeling of Metal Matrix Composite Materials-I. Isothermal Deformation Patterns in Ideal Microstructures. |
1993 |
|
| Authors:
P. E. McHugh; R. J. Asaro; C. F. Shih; BROWN UNIV PROVIDENCE RI DEPT OF ENGINEERING
|
| The mechanical behavior of particulate reinforced mmc, in particular an sic reinforced al-3wt% cu model system, was analyzed numerically. the computational micromechanics approach was taken, i.e. a detailed representation of microstructure in which the material was characterized by a finite deformation, thermo-elastic-viscoplastic crystallographic theory. individual matrix grains and reinforcing particles were represented, in the context of two dimensional repeating unit cell models. the performance of the microstructure under variation in ... |
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| Computational Modeling of Metal Matrix Composite Materials-II. Isothermal Stress-Strain Behavior. |
1993 |
|
| Authors:
P. E. McHugh; R. J. Asaro; C. F. Shih; BROWN UNIV PROVIDENCE RI DEPT OF ENGINEERING
|
| The mechanical behavior of particulate reinforced mmc, in particular an sic reinforced al-3wt% cu model system, was analyzed numerically using the computational micromechanics approach. the isothermal overall stress-strain behavior and its relation to microstructural deformation is examined in detail. the macroscopic strengthening effect of the reinforcement is quantified in terms of a hardness increment. inhomogeneous and localized stress patterns develop in the microstructures. these are predominantly controlled by the positions ... |
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| Computational Modeling of Metal Matrix Composite Materials-III. Comparisons With Phenomenological Models. |
1993 |
|
| Authors:
P. E. McHugh; R. J. Asaro; C. F. Shih; BROWN UNIV PROVIDENCE RI DEPT OF ENGINEERING
|
| The mechanical behavior of particulate mmc, an sic reinforced al-3wt% cu model system, was analyzed numerically and analytically. the results of computational micromechanics modeling are compared with those of simpler analytical/numerical models. models that predict overall composite behavior make use of a result, valid for incompressible materials in small strain, that both pure matrix material and composite harden with the same hardening exponent. results of micromechanical simulations, with power-law hardening ... |
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| Computational Modeling of Metal Matrix Composite Materials-IV. Thermal Deformations. |
1993 |
|
| Authors:
P. E. McHugh; R. J. Asaro; C. F. Shih; BROWN UNIV PROVIDENCE RI DEPT OF ENGINEERING
|
| The mechanical behavior of particulate reinforced mmc, an sic reinforced al-3wt% cu model system, was analyzed using the computational micromechanics approach. the microscale effects of thermo-mechanical processing is investigated in detail. two ideal processes are considered. the first represents a simple quench and the second combines a high temperature compression with a quench. these processes, through applied deformation and thermal expansion mismatch, produce inhomogeneous, and localized, stress and plastic strain ... |
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| Effects of Thermal Residual Stresses and Fiber Packing on Deformation of Metal-Matrix Composites. |
1993 |
|
| Authors:
T. Nakamura; S. Suresh; BROWN UNIV PROVIDENCE RI DEPT OF ENGINEERING
|
| The combined effects of thermal residual stresses and fiber spatial distribution on the deformation of a 6061 aluminum alloy containing a fixed concentration unidirectional boron fibers have been analyzed using detailed finite element models. the geometrical structure includes perfectly periodic, uniformly spaced fiber arrangements in square and hexagonal cells, as well as different cells in which either 30 or 60 fibers are randomly placed in the ductile matrix. the model ... |
|
| Cavity Formation During Tensile Straining of Particulate and Short Fibre Metal Matrix Composites. |
1993 |
|
| Authors:
A. F. Whitehouse; T. W. Clyne; CAMBRIDGE UNIV (UNITED KINGDOM) DEPT OF METALLURGY AND MATERIALS SCIENCE
|
| The formulation of cavities in commercially pure aluminum composites, made by both powder and casting routes and reinforced with alumina, has been monitored using periodic density measurements during tensile testing and microstructural examinations. stable cavities always form well before final failure, usually adjacent to the reinforcement, particularly when it is elongated in the loading direction and has a relatively flat surface normal to the stress axis. sharp corners are not ... |
|
| Role of Coatings in Axial Tensile Strength of Long Fibre-Reinforced Metal-Matrix Composites. |
1993 |
|
| Authors:
Zhenhai Xia; HEBEI INST OF TECH TIANJIN (CHINA)
|
| A model that includes effects of coatings, interfacial behavior, plastic deformation of matrix and reaction zone has been developed for analysis of the behavior of mmc reinforced by coated fibers. the stress concentration caused by the cracks in the reaction zone was calculated from the model and the results show that it can be relaxed by choosing coatings of low modulus and controlling interfacial strength to a relatively low value. ... |
|
| Fracture Mechanics of Ti/Al2O3 Interfaces. |
1993 |
|
| Authors:
H. F. Wang; W. W. Gerberich; C. J. Skowronek; MINNESOTA UNIV MINNEAPOLIS DEPT OF CHEMICAL ENGINEERING AND MATERIALS SCIENCE
|
| Measurement of mixed mode interfacial fracture toughness in ti/al2o3 bimaterial couples has been accomplished by the four-point bending test of sandwich specimens with symmetrical cracks for different processing temperatures and thicknesses of ti interlayers. fracture surfaces and sample cross sections were analyzed by sem, wps, edax, epma and aes. the interfacial fracture toughness measured with four-point bending tests increases with increasing applied bonding temperature up to 950c. above this temperature ... |
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| The Creep and Fracture Resistance of Gamma-TiAl Reinforced With Al2O3 Fibers. |
1993 |
|
| Authors:
C. H. Weber; J. Y. Yang; J. P. A. Loefvander; C. G. Levi; A. G. Evans; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
|
| The creep properties and microstructures of gamma-tial reinforced with continuous al2o3 fibers have been investigated. novel fiber coating concepts have been used to create "weak" fiber/matrix interfaces that allow the fibers to impart enhanced creep and fracture resistance, simultaneously. several major facets of the creep behavior were identified. under conditions of limited fiber fracture, creep-resistant sapphire fibers were found to limit longitudinal creep to a short transient strain, consistent with ... |
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Reports by Keyword(s)
NUCLEAR EXPLOSION DETECTION
