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At least 631 records · Page 35

NASA/NOAA implementation of the USAID-sponsored satellite ground station and data processing facility for Bangladesh

A description is given of a project to transfer multiple environmental satellite data reception, processing, and interpretation capabilities from the U.S. to Bangladesh. The goal of the project is to improve the management of resources related primarily to agriculture, water development, forestry, and fisheries. It is also hoped to improve the existing cyclone/storm surge warning system. An account is given of the interagency and international cooperation underlying the project. The remote-sensing installation in Dhaka, Bangladesh, is described, and the most likely system applications are summarized. Attention is also given to the special requirements concerning this type of technology transfer, and an assessment is made of the project's practical value to Bangladesh.

Dodge, J. C.↗

Pilot climate data system user's guide

Instructions for using the Pilot Climate Data System (PCDS), an interactive, scientific data management system for locating, obtaining, manipulating, and displaying climate-research data are presented. The PCDS currently provides this supoort for approximately twenty data sets. Figures that illustrate the terminal displays which a user sees when he/she runs the PCDS and some examples of the output from this system are included. The capabilities which are described in detail allow a user to perform the following: (1) obtain comprehensive descriptions of a number of climate parameter data sets and the associated sensor measurements from which they were derived; (2) obtain detailed information about the temporal coverage and data volume of data sets which are readily accessible via the PCDS; (3) extract portions of a data set using criteria such as time range and geographic location, and output the data to tape, user terminal, system printer, or online disk files in a special data-set-independent format; (4) access and manipulate the data in these data-set-independent files, performing such functions as combining the data, subsetting the data, and averaging the data; and (5) create various graphical representations of the data stored in the data-set-independent files.

Reph, M. G.↗

DDL system: Design systhesis of digital systems

Digital Systems Design Language was integrated into the CADAT system environment of NASA-MSFC. The major technical aspects of this integration are summarized. Automatic hardware synthesis is now possible starting with a high level description of the system to be synthesized. The DDL system provides a high level design verification capability, thereby minimizing design changes in the later stages of the design cycle. An overview of the DDL system covering the translation, simulation and synthesis capabilities is provided. Two companion documents (the user's and programmer's manuals) are to be consulted for detailed discussions.

Shiva, S. G.↗

DSN frequency and timing system, Mark 4-85

As part of the Deep Space Network (DSN) Mark IVA implementation program, the DSN frequency and timing system is currently undergoing changes. With the implementation of signal processing centers (SPC) at each deep space communications complex (DSCC), major changes to the frequency and timing distribution equipment were necessary. A functional description of the Mark IVA frequency and timing system (FTS) as it exists today and planned capabilities through 1988 is given.

Falin, B. W.↗

Feasibility of mapping velocity flowfields in an SSME powerhead using laser anemometry techniques

Nonintrusive anemometry measurement techniques are investigated for a NASA study of steady and unsteady aerothermal flow phenomena present in three engine component flow environments in the Space Shuttle Main Engine powerhead, the: (1) high-pressure fuel turbopump preburner; (2) turbine; and (3) turnaround duct. Issues considered include identification of feasible means of optical access to the high-pressure high-temperature measurement flow regions, and measurement system compatibility with the test environment. Descriptions of the two-component LDV and Laser Two Focus measurement systems are given whose capabilities include measurements of the time-averaged values of velocity magnitude and flow direction, turbulence intensity, and velocity component correlations.

Pelaccio, D. G.↗

A laboratory breadboard system for dual-arm teleoperation

The computing architecture of a novel dual-arm teleoperation system is described. The novelty of this system is that: (1) the master arm is not a replica of the slave arm; it is unspecific to any manipulator and can be used for the control of various robot arms with software modifications; and (2) the force feedback to the general purpose master arm is derived from force-torque sensor data originating from the slave hand. The computing architecture of this breadboard system is a fully synchronized pipeline with unique methods for data handling, communication and mathematical transformations. The computing system is modular, thus inherently extendable. The local control loops at both sites operate at 100 Hz rate, and the end-to-end bilateral (force-reflecting) control loop operates at 200 Hz rate, each loop without interpolation. This provides high-fidelity control. This end-to-end system elevates teleoperation to a new level of capabilities via the use of sensors, microprocessors, novel electronics, and real-time graphics displays. A description is given of a graphic simulation system connected to the dual-arm teleoperation breadboard system. High-fidelity graphic simulation of a telerobot (called Phantom Robot) is used for preview and predictive displays for planning and for real-time control under several seconds communication time delay conditions. High fidelity graphic simulation is obtained by using appropriate calibration techniques.

Bejczy, A. K.↗

Lunar Observer - Scouting for a moon base

The proposed 1996 Lunar Observer mission to the moon is described. Lunar Observer is intended to acquire the definitive data set of the moon from which an enduring and flexible lunar base site selection can be made. A mission profile is summarized and mission phases defined. The fourteen proposed experiments are described and their measurement capabilities outlined. The spacecraft, a derivation of the planned Mars Observer spacecraft design, is described. A description is included of a subsatellite, which is used to obtain the first measurements of the lunar far side gravity field.

Parker, G. L.↗

Space-tethered atmospheric systems

This paper describes the concept of a space-tethered atmospheric system, a hybrid craft consisting of an orbiting spacecraft and a downward-deployed aerodynamically-configured satellite. Such a system could conduct hypersonic aerothermodynamics and atmospheric science research in the lower thermosphere (150-90 km). Descriptions of specific tethered atmospheric systems, scheduled tether flight validation experiments, candidate research topics and envisioned capabilities and benefits are provided.

Anderson, J. L.↗

Shock and vibration isolation for cyclic exercise in spacecraft

A unique feature of undisturbed space flight is vibration and weight free environments not available on Earth. On long flights, exercise and especially locomotor exercise will be required if the crew is to function in a relatively normal fashion and avoid lengthy rehabilitation on return to Earth. Exercise forces in the low frequency range can amount to 2 to 3 times crew body weight in the frequency range most critical to material science. Therefore, the amount of isolation will need to be orders of magnitude greater than present techniques. The following is a brief rationale of the need for these exercises and a description of exercise forces. Current isolation means and their deficiencies will be described, and a method capable of providing the isolation proposed and work to date will be mentioned.

Thornton, W.↗

The NASA ASTP Combined-Cycle Propulsion Database Project

The National Aeronautics and Space Administration (NASA) communicated its long-term R&D goals for aeronautics and space transportation technologies in its 1997-98 annual progress report (Reference 1). Under "Pillar 3, Goal 9" a 25-year-horizon set of objectives has been stated for the Generation 3 Reusable Launch Vehicle ("Gen 3 RLV") class of space transportation systems. An initiative referred to as "Spaceliner 100" is being conducted to identify technology roadmaps in support of these objectives. Responsibility for running "Spaceliner 100" technology development and demonstration activities have been assigned to NASA's agency-wide Advanced Space Transportation Program (ASTP) office located at the Marshall Space Flight Center. A key technology area in which advances will be required in order to meet these objectives is propulsion. In 1996, in order to expand their focus beyond "allrocket" propulsion systems and technologies (see Appendix A for further discussion), ASTP initiated technology development and demonstration work on combined-cycle airbreathing/rocket propulsion systems (ARTT Contracts NAS8-40890 through 40894). Combined-cycle propulsion (CCP) activities (see Appendix B for definitions) have been pursued in the U.S. for over four decades, resulting in a large documented knowledge base on this subject (see Reference 2). In the fall of 1999 the Combined-Cycle Propulsion Database (CCPD) project was established with the primary purpose of collecting and consolidating CCP related technical information in support of the ASTP's ongoing technology development and demonstration program. Science Applications International Corporation (SAIC) was selected to perform the initial development of the Database under its existing support contract with MSFC (Contract NAS8-99060) because of the company's unique combination of capabilities in database development, information technology (IT) and CCP knowledge. The CCPD is summarized in the descriptive 2-page flyer appended to this paper as Appendix C. The purpose of this paper is to provide the reader with an understanding of the objectives of the CCPD and relate the progress that has been made toward meeting those objectives.

Hyde, Eric H.↗

NASA Programs in Advanced Sensors and Measurement Technology for Aeronautical Applications

There are many challenges facing designers and operators of our next-generation aircraft in meeting the demands for efficiency, safety, and reliability which are will be imposed. This paper discusses aeronautical sensor requirements for a number of research and applications areas pertinent to the demands listed above. A brief overview will be given of aeronautical research measurements, along with a discussion of requirements for advanced technology. Also included will be descriptions of emerging sensors and instrumentation technology which may be exploited for enhanced research and operational capabilities. Finally, renewed emphasis of the National Aeronautics and Space Administration in advanced sensor and instrumentation technology development will be discussed, including project of technology advances over the next 5 years. Emphasis on NASA efforts to more actively advance the state-of-the-art in sensors and measurement techniques is timely in light of exciting new opportunities in airspace development and operation. An up-to-date summary of the measurement technology programs being established to respond to these opportunities is provided.

Conway, Bruce A.↗

Full-Scale Development and Piloting of a Hybrid Digital Twin for Wastewater Operations Optimization

This full-scale pilot of a machine learning based nutrient controller/digital twin is being done as part of The Water Research Foundation (WRF) project 5121: Development of Innovative Predictive Control Strategies for Nutrient Removal. The overall goal of this project is to develop and full-scale test a hybrid (machine learning + mechanistic model) nutrient management controller at four different water resource recovery facilities (WRRFs). The controller demonstrates both short-term optimization functions and predictive capabilities. This project includes the design of the controller, its performance at the WRRFs, and a description of the future improvements.

Johnson, Bruce↗

Design Variants of a Common Habitat for Moon and Mars Exploration

The Common Habitat is a long-duration habitat concept based on the Skylab II architecture that leverages a single, multi-destination design applicable to microgravity Mars transit, 1/6 g lunar surface, 3/8 g Mars surface, and 1 g Earth. A trade study for the Common Habitat will address vertical versus horizontal internal orientation and a crew size of four or eight crew. This has resulted in the creation of four variants of the Common Habitat: Four Crew Horizontal Configuration, Four Crew Vertical Configuration, Eight Crew Horizontal Configuration, and Eight Crew Vertical Configuration. Design guidelines that shaped the four configurations are discussed, including: mission duration, destinations/missions, pressure vessel, hatches and docking, subsystems and utilities, lander integration and offloading, and eight-crew extensibility. Functional capabilities for crew-related systems are also discussed, including: private habitation, meal preparation, meal consumption, medical operations, exercise, group socialization and recreation, human waste collection, hygiene, logistics, spacecraft monitoring and commanding, mission planning, robotics and teleoperation, scientific research, maintenance and fabrication, and EVA. Each of the four Common Habitat designs will be presented, with a deck-by-deck description of each workstation, crew station, or subsystem along with an assessment of its degree of compliance with the guidelines and functional capabilities. Finally, forward work will be identified that will down-select a single Common Habitat. This includes multiple analyses that will be performed on the four variants, a down-selection process, and design refinement goals for the selected variant.

Habitability↗

Model for Process Description: From Picture to Information System

A new model for the development of proces information systems is proposed. It is robust and inexpensive, capable of providing timely, neccessary information to the user by integrating Products, Instructions, Examples, Tools, and Process.

faster better cheaper low cost missions reengineer↗

NASA Simulation Capabilities

This presentation provides a high-level overview of NASA's Future ATM Concepts Evaluation Tool (FACET) with a high-level description of the system's inputs and outputs. This presentation is designed to support the joint simulations that NASA and the Chinese Aeronautical Establishment (CAE) will conduct under an existing Memorandum of Understanding.

ICD↗

Implementation of J-A Methodology Elastic-Plastic Crack Instability Analysis Capability into the WARP-3D Code

Characterization of the near crack-tip stress/strain fields is the foundation of fracture mechanics. The description of the near tip stress field and the prediction of when fracture occurs is well established for brittle materials that exhibit linear elastic behavior. However, in ductile materials or conditions that violate linear elastic assumptions (Aluminum alloys, Al 2024-T3, Al 2024- T351 etc.), the elastic-plastic crack-tip stress fields are characterized by the Hutchison-Rice-Rosengren (HRR) field. The J-integral is commonly used to characterize amplitude of the HRR field under elastic-plastic conditions. The J-integral has been demonstrated for crack-tip fields that are under high constraint conditions (i.e., small-scale plasticity where the J-dominance is maintained). However, as the external load increases, yielding changes from small- to largescale plasticity and usually a loss of constraint (i.e., reduction in the triaxial stress field along the crack front). The loss of constraint leads to the deviation of the crack-tip stress fields from that given by the HRR field. Hence, the J-dominance will be gradually lost and additional parameter(s) are required to quantify the crack-tip stress fields and predict fracture behavior. The assessment objectives were to: 1) implement a two-parameter (i.e., J-A) fracture criterion into an elastic-plastic three-dimensional (3D) finite element analysis (FEA), 2) validate the implementation by comparison with the A parameter from literature data, 3) conduct material characterization tests to quantify the material behavior and provide fracture data for validation of the J-A fracture criteria, and (4) perform evaluations to establish if the J-A criteria can be used to predict fracture in a ductile metallic material (e.g., aluminum alloys). The A parameter in these criteria is the second parameter in a three-term elastic-plastic asymptotic expansion of the neartip stress behavior. A series of extensive FEAs were performed using WARP3D software package to obtain solutions for the A parameter for different specimen configurations. The methodology needed for the estimation of the A parameter in the asymptotic expansion was developed and implemented using Matlab®. A user material (UMAT) routine was used to model the material stress-strain response using a Ramberg-Osgood power law with a hardening exponent (n) and a material coefficient (alpha). This UMAT routine was successfully implemented in WARP3D software and validated through comparison with the experimental data. Three configurations were extracted from published results: 1) center cracked plate (CCP), 2) single edge-cracked plate (SECP), and 3) double edge-cracked plate (DECP). These configurations and four other configurations (three-hole tension (THT)), three-point bend (3PTB), three-hole compact tension (3PCT), and compact tension (CT)) were analyzed to verify the methodology that was developed and implemented into WARP3D. Solutions of the A parameter were obtained for remote tension loading conditions that started with small-scale yielding and continued into the large-scale plasticity regime. The results indicate that the methodology developed can be used to calculate the elastic-plastic J-A parameters for test specimens with a range of crack geometries, material strain hardening behaviors, and loading conditions. The J-A parameters were implemented as fracture criteria and used to predict the test results. For comparison, other fracture criteria were used to predict the same test results. Major findings include: The A constraint parameter A varies with specimen type and applied load thus accurate determination is crucial in predicting the failure load, and the A parameter is asymptotic as the failure load is approached, making an accurate determination difficult (i.e., small differences in the A parameter can cause large variations in failure load) for materials exhibiting elastic-plastic behavior. The failure predictions from J-A methodology were more accurate than the traditionally used KC and J methods, and have comparable scatter to that observed when using the crack-tip opening angle (CTOA) method. However, the J-A methodology requires considerable effort (expertise level and labor) to implement and to evaluate the A parameter for different specimen types and materials, or to apply this methodology to part-through crack (e.g., 3D problems) structural applications.

Hamm, Kenneth R., Jr.↗

The MPACT 2020 Milestone: Safeguards and Security by Design of Future Nuclear Fuel Cycle Facilities.

The Materials Protection, Accounting, and Control Technologies (MPACT) campaign, within the U.S. Department of Energy Office of Nuclear Energy, has developed a Virtual Facility Distributed Test Bed for safeguards and security design for future nuclear fuel cycle facilities. The purpose of the Virtual Test Bed is to bring together experimental and modeling capabilities across the U.S. national laboratory and university complex to provide a one-stop-shop for advanced Safeguards and Security by Design (SSBD). Experimental testing alone of safeguards and security technologies would be cost prohibitive, but testbeds and laboratory processing facilities with safeguards measurement opportunities, coupled with modeling and simulation, provide the ability to generate modern, efficient safeguards and security systems for new facilities. This Virtual Test Bed concept has been demonstrated using a generic electrochemical reprocessing facility as an example, but the concept can be extended to other facilities. While much of the recent work in the MPACT program has focused on electrochemical safeguards and security technologies, the laboratory capabilities have been applied to other facilities in the past (including aqueous reprocessing, fuel fabrication, and molten salt reactors as examples). This paper provides an overview of the Virtual Test Bed concept, a description of the design process, and a baseline safeguards and security design for the example facility. Parallel papers in this issue go into more detail on the various technologies, experimental testing, modeling capabilities, and performance testing.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

SAS4A/SASSYS-1 Verification Testing for Sodium Fast Reactor Application: Acceptance Testing Report

AS4A/SASSYS-1 (SAS) is a simulation tool used to perform deterministic analyses of anticipated events as well as design basis and beyond design basis accidents for advanced liquid-metal-cooled nuclear reactors. With its origin as SAS1A in the late 1960s, the SAS series of codes has been under continuous use and development for over sixty years and represents a critical investment in safety analysis capabilities for the U.S. Department of Energy. To support the dedication effort, this report has been generated to provide a detailed description of the available verification testing. The verification testing presented in this report captures functionality testing, focusing mainly on the testing of specific functions and algorithms for accuracy and precision of output, and interface testing, focusing mainly on the testing of critical input parameters and their valid ranges. Although SAS was developed to support the analysis of any liquid-metal-cooled nuclear reactor, the testing described in this document primarily focuses on the verification of SAS capabilities as they relate to a generic pool-type Sodium Fast Reactor (SFR).

22 GENERAL STUDIES OF NUCLEAR REACTORS↗