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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 595 records · Page 33

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NASA NTRS1997

ATM Quality of Service Parameters at 45 Mbps Using a Satellite Emulator: Laboratory Measurements

Results of 45-Mbps DS3 intermediate-frequency loopback measurements of asynchronous transfer mode (ATM) quality of service parameters (cell error ratio and cell loss ratio) are presented. These tests, which were conducted at the NASA Lewis Research Center in support of satellite-ATM interoperability research, represent initial efforts to quantify the minimum parameters for stringent ATM applications, such as MPEG-1 and MPEG-2 video transmission. Portions of these results were originally presented to the International Telecommunications Union's ITU-R Working Party 4B in February 1996 in support of their Draft Preliminary Recommendation on the Transmission of ATM Traffic via Satellite.

Ivancic, William D.↗

NASA NTRS2000

Multi-Agent Diagnosis and Control of an Air Revitalization System for Life Support in Space

An architecture of interoperating agents has been developed to provide control and fault management for advanced life support systems in space. In this adjustable autonomy architecture, software agents coordinate with human agents and provide support in novel fault management situations. This architecture combines the Livingstone model-based mode identification and reconfiguration (MIR) system with the 3T architecture for autonomous flexible command and control. The MIR software agent performs model-based state identification and diagnosis. MIR identifies novel recovery configurations and the set of commands required for the recovery. The AZT procedural executive and the human operator use the diagnoses and recovery recommendations, and provide command sequencing. User interface extensions have been developed to support human monitoring of both AZT and MIR data and activities. This architecture has been demonstrated performing control and fault management for an oxygen production system for air revitalization in space. The software operates in a dynamic simulation testbed.

Malin, Jane T.↗

NASA NTRS1999

Reflections on Descriptive Psychology: NASA, Media and Technology, Observation

At NASA, we have used methods of Descriptive Psychology (DP) to solve problems in several areas: Simulation of proposed Lunar/Mars missions at high level to assess feasibility and needs in the robotics and automation areas. How we would go about making a "person-like" robot. Design and implementation of Systems Engineering practices on behalf of future projects with emphasis on interoperability. Design of a Question and Answer dialog system to handle student questions about Advanced Life Support (ALS) systems - students learn biology by applying it to ALS projects.

Aucoin, Paschal J., Jr.↗

NASA NTRS2000

NASA/University JOint VEnture (JOVE) Program. VIXEN(tm): Object-Oriented, Technology-Adaptive, Virtual Information Exchange Environment

Vixen is a collection of enabling technologies for uninhibited distributed object computing. In the Spring of 1995 when Vixen was proposed, it was an innovative idea very much ahead of its time. But today the technologies proposed in Vixen have become standard technologies for Enterprise Computing. Sun Microsystems J2EE/EJB specifications, among others, are independently proposed technologies of the Vixen type. I have brought Vixen completely under the J2EE standard in order to maximize interoperability and compatibility with other computing industry efforts. Vixen and the Enterprise JavaBean (EJB) Server technologies are now practically identical; OIL, another Vixen technology, and the Java Messaging System (JMS) are practically identical; and so on. There is no longer anything novel or patentable in the Vixen work performed under this grant. The above discussion, notwithstanding, my independent development of Vixen has significantly helped me, my university, my students and the local community. The undergraduate students who worked with me in developing Vixen have enhanced their expertise in what has become the cutting edge technology of their industry and are therefore well positioned for lucrative employment opportunities in the industry. My academic department has gained a new course: "Multi-media System Development", which provides a highly desirable expertise to our students for employment in any enterprise today. The many Outreach Programs that I conducted during this grant period have exposed local Middle School students to the contributions that NASA is making in our society as well as awakened desires in many such students for careers in Science and Technology. I have applied Vixen to the development of two software packages: (a) JAS: Joshua Application Server - which allows a user to configure an EJB Server to serve a J2EE compliant application over the world wide web; (b) PCM: Professor Course Manager: a J2EE compliant application for configuring a course for distance learning. These types of applications are, however, generally available in the industry today.

Anyiwo, Joshua C.↗

NASA NTRS2000

ACTS Ka-Band Earth Stations: Technology, Performance, and Lessons Learned

The Advanced Communications Technology Satellite (ACTS) Project invested heavily in prototype Ka-band satellite ground terminals to conduct an experiments program with the ACTS satellite. The ACTS experiment's program proposed to validate Ka-band satellite and ground station technology. demonstrate future telecommunication services. demonstrate commercial viability and market acceptability of these new services, evaluate system networking and processing technology, and characterize Ka-band propagation effects, including development of techniques to mitigate signal fading. This paper will present a summary of the fixed ground terminals developed by the NASA Glenn Research Center and its industry partners, emphasizing the technology and performance of the terminals (Part 1) and the lessons learned throughout their six year operation including the inclined orbit phase of operations (Full Report). An overview of the Ka-band technology and components developed for the ACTS ground stations is presented. Next. the performance of the ground station technology and its evolution during the ACTS campaign are discussed to illustrate the technical tradeoffs made during the program and highlight technical advances by industry to support the ACTS experiments program and terminal operations. Finally. lessons learned during development and operation of the user terminals are discussed for consideration of commercial adoption into future Ka-band systems. The fixed ground stations used for experiments by government, academic, and commercial entities used reflector based offset-fed antenna systems ranging in size from 0.35m to 3.4m antenna diameter. Gateway earth stations included two systems, referred to as the NASA Ground Station (NGS) and the Link Evaluation Terminal (LET). The NGS provides tracking, telemetry, and control (TT&C) and Time Division Multiple Access (TDMA) network control functions. The LET supports technology verification and high data rate experiments. The ground stations successfully demonstrated many services and applications at Ka-band in three different modes of operation: circuit switched TDMA using the satellite on-board processor, satellite switched SS-TDMA applications using the on-board Microwave Switch Matrix (MSM), and conventional transponder (bent-pipe) operation. Data rates ranged from 4.8 kbps up to 622 Mbps. Experiments included: 1) low rate (4.8- 1 00's kbps) remote data acquisition and control using small earth stations, 2) moderate rate (1-45 Mbps) experiments included full duplex voice and video conferencing and both full duplex and asymmetric data rate protocol and network evaluation using mid-size ground stations, and 3) link characterization experiments and high data rate (155-622 Mbps) terrestrial and satellite interoperability application experiments conducted by a consortium of experimenters using the large transportable ground stations.

Reinhart, Richard C.↗

NASA NTRS2000

Endpoint Security Using Biometric Authentication for Secure Remote Mission Operations

We propose a flexible security authentication solution for the spacecraft end-user, which will allow the user to interact over Internet with the spacecraft, its instruments, or with the ground segment from anywhere, anytime based on the user's pre-defined set of privileges. This package includes biometrics authentication products, such as face, voice or fingerprint recognition, authentication services and procedures, such as: user registration and verification over the Internet and user database maintenance, with a configurable schema of spacecraft users' privileges. This fast and reliable user authentication mechanism will become an integral part of end-to-end ground-to-space secure Internet communications and migration from current practice to the future. All modules and services of the proposed package are commercially available and built to the NIST BioAPI standard, which facilitates "pluggability" and interoperability.

Donohue, John T.↗

NASA NTRS2000

Are Fibre Channel SANs a Commodity?

The goal of this work is to evaluate the feasibility of putting together a Fibre Channel Storage Area Network with heterogeneous hardware running both open-source and commercial operating systems. Adherence to the Fibre Channel Specification is supposed to guarantee interoperability in such an environment. We also want to evaluate how difficult it might be to put together a SAN using open-source components. While all the commercial vendors provide Fibre Channel support, this comes at a cost, e.g., not only O/S and drivers, but usually an expensive support contract. The open-source model could lower the cost of building and maintaining a SAN. Of course, for this to be the case, the open-source platforms would have to provide the functionality to construct a SAN. We are assembling a Fibre Channel SAN from heterogeneous hardware (i386, alpha, sparc) running *BSD, Linux, Tru64, NT and Solaris operating systems. We are running several tests to investigate the level of Fibre Channel support provided by each OS. Our current testbed is specified in the table below. Currently, it only contains open-source platforms. We plan to add a PC running OpenBSD, as well as the following commercial systems: Sun Ultra 1/Solaris, DEC AlphaServer 4000/Tru64 Unix, Pentium Pro PC/Windows NT.

Becker, Jeff↗

NASA NTRS2001

Processors, Pipelines, and Protocols for Advanced Modeling Networks

Predictive capabilities arise from our understanding of natural processes and our ability to construct models that accurately reproduce these processes. Although our modeling state-of-the-art is primarily limited by existing computational capabilities, other technical areas will soon present obstacles to the development and deployment of future predictive capabilities. Advancement of our modeling capabilities will require not only faster processors, but new processing algorithms, high-speed data pipelines, and a common software engineering framework that allows networking of diverse models that represent the many components of Earth's climate and weather system. Development and integration of these new capabilities will pose serious challenges to the Information Systems (IS) technology community. Designers of future IS infrastructures must deal with issues that include performance, reliability, interoperability, portability of data and software, and ultimately, the full integration of various ES model systems into a unified ES modeling network.

Coughlan, Joseph↗

NASA NTRS2001

Considerations and Architectures for Inter-Satellite Communications in Distributed Spacecraft Systems

This paper will identify the important characteristics and requirements necessary for inter-satellite communications in distributed spacecraft systems and present analysis results focusing on architectural and protocol comparisons. Emerging spacecraft systems plan to deploy multiple satellites in various "distributed" configurations ranging from close proximity formation flying to widely separated constellations. Distributed spacecraft configurations provide advantages for science exploration and operations since many activities useful for missions may be better served by distributing them between spacecraft. For example, many scientific observations can be enhanced through spatially separated platforms, such as for deep space interferometry. operating multiple distributed spacecraft as a mission requires coordination that may be best provided through inter-satellite communications. For example, several future distributed spacecraft systems envision autonomous operations requiring relative navigational calculations and coordinated attitude and position corrections. To conduct these operations, data must be exchanged between spacecraft. Direct cross-links between satellites provides an efficient and practical method for transferring data and commands. Unlike existing "bent-pipe" relay networks supporting space missions, no standard or widely-used method exists for cross-link communications. Consequently, to support these future missions, the characteristics necessary for inter-satellite communications need to be examined. At first glance, all of the missions look extremely different. Some missions call for tens to hundreds of nano-satellites in constant communications in close proximity to each other. Other missions call for a handful of satellites communicating very slowly over thousands to hundreds of thousands of kilometers. The paper will first classify distributed spacecraft missions to help guide the evaluation and definition of cross-link architectures and approaches. Based on this general classification, the paper will examine general physical layer parameters, such as frequency bands and data rates, necessary to support the missions. The paper will also identify classes of communication architectures that may be employed, ranging from fully distributed to centralized topologies. Numerous factors, such as number of spacecraft, must be evaluated when attempting to pick a communications architecture. Also important is the stability of the formation from a communications standpoint. For example, do all of the spacecraft require equal bandwidth and are spacecraft allowed to enter and leave a formation? The type of science mission being attempted may also heavily influence the communications architecture. In addition, the paper will assess various parameters and characteristics typically associated with the data link layer. The paper will analyze the performance of various multiple access techniques given the operational scenario, requirements, and communication topologies envisioned for missions. This assessment will also include a survey of existing standards and their applicability for distributed spacecraft systems. An important consideration includes the interoperability of the lower layers (physical and data link) examined in this paper with the higher layer protocols(network) envisioned for future space internetworking. Finally, the paper will define a suggested path, including preliminary recommendations, for defining and developing a standard for intersatellite communications based on the classes of distributed spacecraft missions and analysis results.

Edwards, Bernard↗

NASA NTRS2001

The State of NASA's Information Power Grid

This viewgraph presentation transfers the concept of the power grid to information sharing in the NASA community. An information grid of this sort would be characterized as comprising tools, middleware, and services for the facilitation of interoperability, distribution of new technologies, human collaboration, and data management. While a grid would increase the ability of information sharing, it would not necessitate it. The onus of utilizing the grid would rest with the users.

Johnston, William E.↗

NASA NTRS2001

Runway Incursion Prevention System ADS-B and DGPS Data Link Analysis Dallas-Fort Worth International Airport

A Runway Incursion Prevention System (RIPS) was tested at the Dallas - Ft. Worth International Airport in October 2000. The system integrated airborne and ground components to provide both pilots and controllers with enhanced situational awareness, supplemental guidance cues, a real-time display of traffic information, and warning of runway incursions in order to prevent runway incidents while also improving operational capability. Rockwell Collins provided and supported a prototype Automatic Dependent Surveillance - Broadcast (ADS-B) system using 1090 MHz and a prototype Differential GPS (DGPS) system onboard the NASA Boeing 757 research aircraft. This report describes the Rockwell Collins contributions to the RIPS flight test, summarizes the development process, and analyzes both ADS-B and DGPS data collected during the flight test. In addition, results are report on interoperability tests conducted between the NASA Advanced General Aviation Transport Experiments (AGATE) ADS-B flight test system and the NASA Boeing 757 ADS-B system.

Timmerman, J.↗

NASA NTRS2001

Toward a Virtual Solar Observatory: Starting Before the Petabytes Fall

Although a few, large, space- and groundbased solar physics databases exist at selected locations, there is as yet only limited standardization or interoperability. I describe the outline of a plan to facilitate access to a distributed network of online solar data archives, both large and small. The underlying principle is that the user need not know where- the data are, only how to specify which data are desired. At the least, such an approach could considerably simplify the scientific user's access to the enormous amount of solar physics data to be obtained in the next decade. At best, it might mean the withering away of traditional data centers, and all the bureaucracy they entail. This work is supported by the Sun-Earth Connections Division of NASA Office of Space Science, thanks to an anomalous act of largess on the part of the 2001 SEC Senior Review.

Gurman, Joseph↗

NASA NTRS2002

MDP: Reliable File Transfer for Space Missions

This paper presents work being done at NASA/GSFC (Goddard Space Flight Center) by the Operating Missions as Nodes on the Internet (OMNI) project to demonstrate the application of the Multicast Dissemination Protocol (MDP) to space missions to reliably transfer files. This work builds on previous work by the OMNI project to apply Internet communication technologies to space communication. The goal of this effort is to provide an inexpensive, reliable, standard, and interoperable mechanism for transferring files in the space communication environment. Limited bandwidth, noise, delay, intermittent connectivity, link asymmetry, and one-way links are all possible issues for space missions. Although these are link-layer issues, they can have a profound effect on the performance of transport and application level protocols. MDP, a UDP (User Datagram Protocol)-based reliable file transfer protocol, was designed for multicast environments which have to address these same issues, and it has done so successfully. Developed by the Naval Research Lab in the mid 1990s, MDP is now in daily use by both the US Post Office and the DoD (Department of Defense). This paper describes the use of MDP to provide automated end-to-end data flow for space missions. It examines the results of a parametric study of MDP in a simulated space link environment and discusses the results in terms of their implications for space missions. Lessons learned are addressed, which suggest minor enhancements to the MDP user interface to add specific features for space mission requirements, such as dynamic control of data rate, and a checkpoint/resume capability. These are features that are provided for in the protocol, but are not implemented in the sample MDP application that was provided. A brief look is also taken at the status of standardization. A version of MDP known as NORM (Nack Oriented Reliable Multicast) is in the process of becoming an IETF (Internet Engineering Task Force) standard.

Rash, James↗

NASA NTRS2002

MDP: Reliable File Transfer for Space Missions

This paper presents work being done at NASA/GSFC by the Operating Missions as Nodes on the Internet (OMNI) project to demonstrate the application of the Multicast Dissemination Protocol (MDP) to space missions to reliably transfer files. This work builds on previous work by the OMNI project to apply Internet communication technologies to space communication. The goal of this effort is to provide an inexpensive, reliable, standard, and interoperable mechanism for transferring files in the space communication environment. Limited bandwidth, noise, delay, intermittent connectivity, link asymmetry, and one-way links are all possible issues for space missions. Although these are link-layer issues, they can have a profound effect on the performance of transport and application level protocols. MDP, a UDP-based reliable file transfer protocol, was designed for multicast environments which have to address these same issues, and it has done so successfully. Developed by the Naval Research Lab in the mid 1990's, MDP is now in daily use by both the US Post Office and the DoD. This paper describes the use of MDP to provide automated end-to-end data flow for space missions. It examines the results of a parametric study of MDP in a simulated space link environment and discusses the results in terms of their implications for space missions. Lessons learned are addressed, which suggest minor enhancements to the MDP user interface to add specific features for space mission requirements, such as dynamic control of data rate, and a checkpoint/resume capability. These are features that are provided for in the protocol, but are not implemented in the sample MDP application that was provided. A brief look is also taken at the status of standardization. A version of MDP known as NORM (Neck Oriented Reliable Multicast) is in the process of becoming an IETF standard.

Rash, James↗

NASA NTRS2002

NETMARK

This presentation discuss NASA's proposed NETMARK knowledge management tool which aims 'to control and interoperate with every block in a document, email, spreadsheet, power point, database, etc. across the lifecycle'. Topics covered include: system software requirements and hardware requirements, seamless information systems, computer architecture issues, and potential benefits to NETMARK users.

Maluf, David A.↗

NASA NTRS2002

Secure Remote Access Issues in a Control Center Environment

The ISS finally reached an operational state and exists for local and remote users. Onboard payload systems are managed by the Huntsville Operations Support Center (HOSC). Users access HOSC systems by internet protocols in support of daily operations, preflight simulation, and test. In support of this diverse user community, a modem security architecture has been implemented. The architecture has evolved over time from an isolated but open system to a system which supports local and remote access to the ISS over broad geographic regions. This has been accomplished through the use of an evolved security strategy, PKI, and custom design. Through this paper, descriptions of the migration process and the lessons learned are presented. This will include product decision criteria, rationale, and the use of commodity products in the end architecture. This paper will also stress the need for interoperability of various products and the effects of seemingly insignificant details.

Pitts, Lee↗

NASA NTRS2002

Inter-Satellite Communications Considerations and Requirements for Distributed Spacecraft and Formation Flying Systems

In order to avoid selecting inadequate inter-spacecraft cross-link communications standards for Distributed Spacecraft System (DSS) missions, it is first necessary to identify cross-link communications strategies and requirements common to a cross-section of proposed missions. This paper addresses the cross-link communication strategies and requirements derived from a survey of 39 DSS mission descriptions that are projected for potential launch within the next 20 years. The inter-spacecraft communications strategies presented are derived from the topological and communications constraints from the DSS missions surveyed. Basic functional requirements are derived from an analysis of the fundamental activities that must be undertaken to establish and maintain a cross-link between two DSS spacecraft. Cross-link bandwidth requirements are derived from high-level assessments of mission science objectives and operations concepts. Finally, a preliminary assessment of possible cross-link standards is presented within the context of the basic operational and interoperability requirements.

Kwadrat, Carl F.↗

NASA NTRS2003

Compressing Aviation Data in XML Format

Design, operations and maintenance activities in aviation involve analysis of variety of aviation data. This data is typically in disparate formats making it difficult to use with different software packages. Use of a self-describing and extensible standard called XML provides a solution to this interoperability problem. XML provides a standardized language for describing the contents of an information stream, performing the same kind of definitional role for Web content as a database schema performs for relational databases. XML data can be easily customized for display using Extensible Style Sheets (XSL). While self-describing nature of XML makes it easy to reuse, it also increases the size of data significantly. Therefore, transfemng a dataset in XML form can decrease throughput and increase data transfer time significantly. It also increases storage requirements significantly. A natural solution to the problem is to compress the data using suitable algorithm and transfer it in the compressed form. We found that XML-specific compressors such as Xmill and XMLPPM generally outperform traditional compressors. However, optimal use of Xmill requires of discovery of optimal options to use while running Xmill. This, in turn, depends on the nature of data used. Manual disc0ver.y of optimal setting can require an engineer to experiment for weeks. We have devised an XML compression advisory tool that can analyze sample data files and recommend what compression tool would work the best for this data and what are the optimal settings to be used with a XML compression tool.

Patel, Hemil↗