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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

The df: A proposed data format standard

A standard is proposed describing a portable format for electronic exchange of data in the physical sciences. Writing scientific data in a standard format has three basic advantages: portability; the ability to use metadata to aid in interpretation of the data (understandability); and reusability. An improperly formulated standard format tends towards four disadvantages: (1) it can be inflexible and fail to allow the user to express his data as needed; (2) reading and writing such datasets can involve high overhead in computing time and storage space; (3) the format may be accessible only on certain machines using certain languages; and (4) under some circumstances it may be uncertain whether a given dataset actually conforms to the standard. A format was designed which enhances these advantages and lessens the disadvantages. The fundamental approach is to allow the user to make her own choices regarding strategic tradeoffs to achieve the performance desired in her local environment. The choices made are encoded in a specific and portable way in a set of records. A fully detailed description and specification of the format is given, and examples are used to illustrate various concepts. Implementation is discussed.

Lait, Leslie R.↗
NASA NTRS1993

Interoperability through standardization: Electronic mail, and X Window systems

Since the introduction of computing machines, there has been continual advances in computer and communication technologies and approaching limits. The user interface has evolved from a row of switches, character based interface using teletype terminals and then video terminals, to present day graphical user interface. It is expected that next significant advances will come in the availability of services, such as electronic mail and directory services, as the standards for applications are developed and in the 'easy to use' interfaces, such as Graphical User Interface for example Window and X Window, which are being standardized. Various proprietary electronic mail (email) systems are in use within organizations at each center of NASA. Each system provides email services to users within an organization, however the support for email services across organizations and across centers exists at centers to a varying degree and is often easy to use. A recent NASA email initiative is intended 'to provide a simple way to send email across organizational boundaries without disruption of installed base.' The initiative calls for integration of existing organizational email systems through gateways connected by a message switch, supporting X.400 and SMTP protocols, to create a NASA wide email system and for implementation of NASA wide email directory services based on OSI standard X.500. A brief overview of MSFC efforts as a part of this initiative are described. Window based graphical user interfaces make computers easy to use. X window protocol has been developed at Massachusetts Institute of Technology in 1984/1985 to provide uniform window based interface in a distributed computing environment with heterogenous computers. It has since become a standard supported by a number of major manufacturers. Z Windows systems, terminals and workstations, and X Window applications are becoming available. However impact of its use in the Local Area Network environment on the network traffic are not well understood. It is expected that the use of X Windows systems will increase at MSFC especially for Unix based systems. An overview of X Window protocol is presented and its impact on the network traffic is examined. It is proposed that an analytical model of X Window systems in the network environment be developed and validated through the use of measurements to generate application and user profiles.

Amin, Ashok T.↗
NASA NTRS1994

Frequency standards from industry over the next 25 years

Present and possible future performance for many of the existing and new commercial frequency standards is presented here. Recent progress in the gas cell atomic standards with regards to size and cost is significant and considerable improvement is expected. Cesium beam standards will benefit in stability and accuracy from optical pumping. Cooled hydrogen masers will offer extremely good stability. Advances in trapped ion and cesium fountain technologies make them good high performance candidates for the future. The quartz oscillator field is more mature and consequently performance improvements for the future are going to be less spectacular. Oscillators stabilized to GPS will have many applications. Recent performance of cooled microwave dielectric resonator oscillators is very good and they offer the promise of serving as flywheel oscillators for advanced performance atomic standards.

Cutler, Leonard S.↗
NASA NTRS1995

Implementation of a standard format for GPS common view data

A new format for standardizing common view time transfer data, recommended by the Consultative Committee for the Definition of the Second, is being implemented in receivers commonly used for contributing data for the generation of International Atomic Time. We discuss three aspects of this new format that potentially improve GPS common-view time transfer: (1) the standard specifies the method for treating short term data, (2) it presents data in consistent formats including needed terms not previously available, and (3) the standard includes a header of parameters important for the GPS common-view process. In coordination with the release of firmware conforming to this new format the Bureau International des Poids et Mesures will release future international track schedules consistent with the new standard.

Weiss, Marc A.↗
NASA NTRS1996

Digital optical tape: Technology and standardization issues

During the coming years, digital data storage technologies will continue an aggressive growth to satisfy the user's need for higher storage capacities, higher data transfer rates and long-term archival media properties. Digital optical tape is a promising technology to satisfy these user's needs. As any emerging data storage technology, the industry faces many technological and standardization challenges. The technological challenges are great, but feasible to overcome. Although it is too early to consider formal industry standards, the optical tape industry has decided to work together by initiating prestandardization efforts that may lead in the future to formal voluntary industry standards. This paper will discuss current industry optical tape drive developments and the types of standards that will be required for the technology. The status of current industry prestandardization efforts will also be discussed.

Podio, Fernando L.↗
NASA NTRS1998

Study Methods to Standardize Thermography NDE

The purpose of this work is to develop thermographic inspection methods and standards for use in evaluating structural composites and aerospace hardware. Qualification techniques and calibration methods are investigated to standardize the thermographic method for use in the field. Along with the inspections of test standards structural hardware, support hardware is designed and fabricated to aid in the thermographic process. Also, a standard operating procedure is developed for performing inspections with the Bales Thermal Image Processor (TIP). Inspections are performed on a broad range of structural composites. These materials include various graphite/epoxies, graphite/cyanide-ester, graphite/silicon-carbide, graphite phenolic and Keviar/epoxy. Also metal honeycomb (titanium and aluminum faceplates over an aluminum honeycomb core) structures are investigated. Various structural shapes are investigated and the thickness of the structures vary from as few as 3 plies to as many as 80 plies. Special emphasis is placed on characterizing defects in attachment holes and bondlines, in addition to those resulting from impact damage and the inclusion of foreign matter. Image processing through statistical analysis and digital filtering is investigated to enhance the quality and quantify the NDE thermal images when necessary.

Walker, James L.↗
NASA NTRS1993

Software Formal Inspections Standard

This Software Formal Inspections Standard (hereinafter referred to as Standard) is applicable to NASA software. This Standard defines the requirements that shall be fulfilled by the software formal inspections process whenever this process is specified for NASA software. The objective of this Standard is to define the requirements for a process that inspects software products to detect and eliminate defects as early as possible in the software life cycle. The process also provides for the collection and analysis of inspection data to improve the inspection process as well as the quality of the software.

Source record↗
NASA NTRS1998

Study Methods to Standardize Thermography NDE

The purpose of this work is to develop thermographic inspection methods and standards for use in evaluating structural composites and aerospace hardware. Qualification techniques and calibration methods are investigated to standardize the thermographic method for use in the field. Along with the inspections of test standards structural hardware, support hardware is designed and fabricated to aid in the thermographic process. Also, a standard operating procedure is developed for performing inspections with the Bales Thermal Image Processor (TIP). Inspections are performed on a broad range of structural composites. These materials include graphite/epoxies, graphite/cyanide-ester, graphite/silicon-carbide, graphite phenolic and Kevlar/epoxy. Also metal honeycomb (titanium and aluminum faceplates over an aluminum honeycomb core) structures are investigated. Various structural shapes are investigated and the thickness of the structures vary from as few as 3 plies to as many as 80 plies. Special emphasis is placed on characterizing defects in attachment holes and bondlines, in addition to those resulting from impact damage and the inclusion of foreign matter. Image processing through statistical analysis and digital filtering is investigated to enhance the quality and quantify the NDE thermal images when necessary.

Walker, James L.↗
NASA NTRS1999

The Role of Metadata Standards in EOSDIS Search and Retrieval Applications

Metadata standards play a critical role in data search and retrieval systems. Metadata tie software to data so the data can be processed, stored, searched, retrieved and distributed. Without metadata these actions are not possible. The process of populating metadata to describe science data is an important service to the end user community so that a user who is unfamiliar with the data, can easily find and learn about a particular dataset before an order decision is made. Once a good set of standards are in place, the accuracy with which data search can be performed depends on the degree to which metadata standards are adhered during product definition. NASA's Earth Observing System Data and Information System (EOSDIS) provides examples of how metadata standards are used in data search and retrieval.

Pfister, Robin↗
NASA NTRS1999

Plug and Play Integration through Space Object Standardization

Plug and play is an industry standard promoted by Intel and Microsoft, and others that allows users to add and remove various input and output devices without making specific customizations to their systems. The idea behind concept is that using standard products eases integration of components and promotes capabilities of conforming products. The concept works because vendors comply with a standard specification. This paper reports the development of a reference architecture for the mission control domain, which is leveraging off this revolutionary concept. Standards are being developed at the application layer, which enable "plug and play" of mission software products. A Mission Control, reference architecture has been defined. For each sub-domain, the interfaces are modeled in Interface Definition Language (IDL). A subset of the IDL has been developed within both commercial off-the-shelf (COTS) and government (GOTS) products. Selected vendors have agreed to modify their products to be compatible with the defined IDL. The plug and play integration of these different products has been validated in a demonstration testbed.

Boyce, Leslye↗
NASA NTRS2000

Using the World Primary Standard Dobson Spectrometer to Monitor the Stability of a Multi-Instrument Satellite Ozone Dataset

NASA is creating a long term satellite ozone time series by combining data from multiple instruments: Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) (1978 - 1993), Meteor 3 TOMS (1991 - 1994), Earth Probe TOMS (1996 - present), Nimbus 7 SB-JV (1978 - 1990), NOAA-9 Solar Backscatter UV Spectrometer (SBUV/2) (1984 - 1997), NOAA-11 SBUV/2 (1989 - 1994), and NOAA-14 SBUV/2 (1995 - present). The stability of individual data sets and possible instrument-to-instrument differences are best checked by comparison with ground-based measurements. We have examined the time dependence of the calibrations of these instruments by comparing satellite derived ozone with that measured by the world primary standard Dobson spectrometer No. 83. This instrument has been maintained since 1962 as a standard for total ozone to an uncertainty of plus or minus 0.5%. Measurements of AD pair ozone made with instrument No. 83 at Mauna Loa observatory most summers since 1979 were compared with coincident TOMS and SBUV(/2) ozone measurements. The comparison shows that the various instruments were stable relative to instrument No. 83 to within about plus or minus 1%, but that there are instrument-to-instrument biases of as much as 3%. Earth Probe TOMS, for example, is 1% to 2% high relative to Nimbus 7 TOMS when the world standard instrument is used as a transfer standard. Similar results are seen when comparisons are made with an ensemble of 41 Dobson stations throughout the world, demonstrating that the ensemble as a whole is stable despite the fact that many instruments within the ensemble have clear calibration changes.

McPeters, R.D.↗
NASA NTRS2003

Engineering Lessons Learned and Technical Standards Integration: Capturing Key Technologies for Future Space Missions

Capturing engineering lessons learned derived from past experiences and new technologies, then integrating them with technical standards, provides a viable process for enhancing engineering capabilities. The development of future space missions will require ready access, not only to the latest technical standards, but also to lessons learned derived from past experiences and new technologies. The integration of this information such that it is readily accessible by engineering and programmatic personnel is a key aspect of enabling technology. This paper addresses the development of a new and innovative Lessons Learned/Best Practices/Applications Notes--Standards Integration System, including experiences with its initial implementation as a pilot effort within the NASA Technical Standards Program. Included are metrics on the Program, feedbacks from users, future plans, and key issues that are being addressed to expand the System's utility. The objective is the enhancement of engineering capabilities on all aspects of systems development applicable to the success of future space missions.

Mellen, Daniele P.↗
NASA NTRS2003

A Gold Standards Approach to Training Instructors to Evaluate Crew Performance

The Advanced Qualification Program requires that airlines evaluate crew performance in Line Oriented Simulation. For this evaluation to be meaningful, instructors must observe relevant crew behaviors and evaluate those behaviors consistently and accurately against standards established by the airline. The airline industry has largely settled on an approach in which instructors evaluate crew performance on a series of event sets, using standardized grade sheets on which behaviors specific to event set are listed. Typically, new instructors are given a class in which they learn to use the grade sheets and practice evaluating crew performance observed on videotapes. These classes emphasize reliability, providing detailed instruction and practice in scoring so that all instructors within a given class will give similar scores to similar performance. This approach has value but also has important limitations; (1) ratings within one class of new instructors may differ from those of other classes; (2) ratings may not be driven primarily by the specific behaviors on which the company wanted the crews to be scored; and (3) ratings may not be calibrated to company standards for level of performance skill required. In this paper we provide a method to extend the existing method of training instructors to address these three limitations. We call this method the "gold standards" approach because it uses ratings from the company's most experienced instructors as the basis for training rater accuracy. This approach ties the training to the specific behaviors on which the experienced instructors based their ratings.

Baker, David P.↗
NASA NTRS2003

Standards Development Activities at White Sands Test Facility

The development of standards and standard activities at the JSC White Sands Test Facility (WSTF) has been expanded to include the transfer of technology and standards to voluntary consensus organizations in five technical areas of importance to NASA. This effort is in direct response to the National Technology Transfer Act designed to accelerate transfer of technology to industry and promote government-industry partnerships. Technology transfer is especially important for WSTF, whose longterm mission has been to develop and provide vital propellant safety and hazards information to aerospace designers, operations personnel, and safety personnel. Meeting this mission is being accomplished through the preparation of consensus guidelines and standards, propellant hazards analysis protocols, and safety courses for the propellant use of hydrogen, oxygen, and hypergols, as well as the design and inspection of spacecraft pressure vessels and the use of pyrovalves in spacecraft propulsion systems. The overall WSTF technology transfer program is described and the current status of technology transfer activities are summarized.

Baker, D. L.↗
NASA NTRS2004

A Standard Atmosphere of the Antarctic Plateau

Climate models often rely on standard atmospheres to represent various regions; these broadly capture the important physical and radiative characteristics of regional atmospheres, and become benchmarks for simulations by researchers. The high Antarctic plateau is a significant region of the earth for which such standard atmospheres are as yet unavailable. Moreover, representative profiles from atmospheres over other regions of the planet, including &om the northern high latitudes, are not comparable to the atmosphere over the Antarctic plateau, and are therefore only of limited value as substitutes in climate models. Using data from radiosondes, ozonesondes and satellites along with other observations from South Pole station, typical seasonal atmospheric profiles for the high plateau are compiled. Proper representations of rapidly changing ozone concentrations (during the ozone hole) and the effect of surface elevation on tropospheric temperatures are discussed. The differences between standard profiles developed here and the most similar standard atmosphere that already exists - namely, the Arctic Winter profile - suggest that these new profiles will be extremely useful to make accurate representations of the atmosphere over the high plateau.

Mahesh, Ashwin↗
NASA NTRS2002

CAD/CAE Integration Enhanced by New CAD Services Standard

A Government-industry team led by the NASA Glenn Research Center has developed a computer interface standard for accessing data from computer-aided design (CAD) systems. The Object Management Group, an international computer standards organization, has adopted this CAD services standard. The new standard allows software (e.g., computer-aided engineering (CAE) and computer-aided manufacturing software to access multiple CAD systems through one programming interface. The interface is built on top of a distributed computing system called the Common Object Request Broker Architecture (CORBA). CORBA allows the CAD services software to operate in a distributed, heterogeneous computing environment.

Claus, Russell W.↗
NASA NTRS2006

Development of Standardized Lunar Regolith Simulant Materials

Lunar exploration requires studies using standardized testing procedures. Previous lunar simulants focused on physical aspects of the lunar regolith. Renewed lunar exploration requires standardized lunar regolith simulant (SLRS) materials that simulate the physical, chemical, and mineralogical properties of the regolith [l]. A root simulant models an end-member, and a derivative is formed by addition of material [2]. The 2005 Workshop recommended a low-Ti mare basalt and a high-Ca highland anorthosite set of roots. Derivatives involve addition of ilmenite and glassy agglutinates [3]. An ideal SLRS material is homogeneous. Geochemical standards are finely-ground to reduce chemical variability, but lunar simulants have a grain size variation and mineralogy that must match the lunar regolith. The simulant homogeneity is monitored using major, minor, and trace element data of progressively smaller samples compared to bulk material. Both chemical and geotechnical properties depend on the contrast from grain to grain. The variability of simulant material is an inherent property that must be taken into account. Simulant production requires monitoring of adherence to simulant requirements and homogeneity during production. Quality control establishes a traceability to a master set of reference standards.

Carpenter, P.↗
NASA NTRS2006

Lunar Regolith Simulant Materials: Recommendations for Standardization, Production, and Usage

Experience gained during the Apollo program demonstrated the need for extensive testing of surface systems in relevant environments, including regolith materials similar to those encountered on the lunar surface. As NASA embarks on a return to the Moon, it is clear that the current lunar sample inventory is not only insufficient to support lunar surface technology and system development, but its scientific value is too great to be consumed by destructive studies. Every effort must be made to utilize standard simulant materials, which will allow developers to reduce the cost, development, and operational risks to surface systems. The Lunar Regolith Simulant Materials Workshop held in Huntsville, AL, on January 24 26, 2005, identified the need for widely accepted standard reference lunar simulant materials to perform research and development of technologies required for lunar operations. The workshop also established a need for a common, traceable, and repeatable process regarding the standardization, characterization, and distribution of lunar simulants. This document presents recommendations for the standardization, production and usage of lunar regolith simulant materials.

Sibille, L.↗