SEARCH · Engineering Papers

Results for “Issue Brief”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21

All sources NASA NTRS DOE OSTI

NASA NTRS2017

Tidal Prediction

Tides are the most predictable of oceanographic phenomena, due both to the simplicity and predictability of the astronomical forcing and to the near linearity of the ocean's dynamical response. In the classical and simplest scenario, tidal prediction is based on harmonic analysis of past measurements at a fixed location. Limits to predictability arise because isolated astronomical spectral lines are broadened into "cusps" of incoherent energy, for example through interactions with non-tidal flows. Tidal prediction at locations without past measurements has historically been a major challenge, but, owing to near-global observations of modern satellite altimeters, the empirical harmonic approach now yields reasonably accurate predictions throughout most of the open ocean. Advances in numerical modeling and data assimilation allow these predictions to be refined (especially in shallow seas where observations remain insufficient to directly constrain tidal wave structure) and extended to include tidal currents. We review recent progress in the development of global and regional-scale tidal prediction capabilities, summarize accuracy of available charts, and briefly consider outstanding issues. Satellite altimetry has also helped unravel the global tidal energy budget and has clarified the role of internal tides as a sink of tidal energy. We summarize these results, and then turn to the challenging problem of predicting internal tides. To the extent that low modes remain coherent with the surface tide, elevations can be directly mapped. We review current efforts in this direction, which are already producing charts with predictive capability. However, internal tides (especially higher modes) interact much more strongly with lower-frequency ocean flows, so a significant fraction of this tidal signal is intermittent and incoherent. We close with a brief review of ongoing efforts to model global tides in combination with wind-forced ocean motions.

Harmonic Constants↗

NASA NTRS1994

Current and future issues in USAF full pressure suit research and development

Although the full pressure suits currently in the USAF operational inventory provide acceptable performance and crew protection for these missions, there is considerable room for improvement, especially in the areas of comfort, mobility, glove and helmet performance, and maintenance/supportability. As future aircraft push the envelope towards operations at higher and higher altitudes and transatmospheric flight, advances in full pressure suit technology will be needed. Also, enhanced pressure suit technology will be required to meet NASA's need for protection during future EVA operations for both on-orbit and planetary surface missions. This presentation will review the results of efforts at the Armstrong Laboratory to develop and demonstrate advanced full pressure suit technology for use in future high-altitude reconnaissance aircraft and transatmospheric vehicle operations. For those readers who may not be familiar with this area of life support equipment, a brief review of the important physiological and operational requirements for full pressure suits used in these applications will be addressed first, followed by a summary of the current state-of-the-art in USAF pressure suit technology. Ongoing and recently completed work on enhanced mobility pressure suit joints and improved pressure suit gloves will then be reviewed. The presentation will conclude with discussion of the technical challenges for successful development of an advanced full pressure suit for aerospace operations in the 21st century.

Scoggins, Terrell E.↗

NASA NTRS1976

Space benefits: The secondary application of aerospace technology in other sectors of the economy

A 'Benefit Briefing Notebook' was prepared for the NASA Technology Utilization Office to provide accurate, convenient, and integrated resource information on the transfer of aerospace technology to other sectors of the U.S. economy. The contents are divided into three sections: (1) transfer overview, (2) benefit cases, and (3) indexes. The transfer overview section provides a general perspective for technology transfer from NASA to other organizations. In addition to a description of the basic transfer modes, the selection criteria for notebook examples and the kinds of benefit data they contain are also presented. The benefits section is subdivided into nineteen subject areas. Each subsection presents one or more key issues of current interest, with discrete transfer cases related to each key issue. Additional transfer examples relevant to each subject area are then presented. Pertinent transfer data are given at the end of each example.

Source record↗

NASA NTRS2009

Human Research Program Human Health Countermeasures Element Extravehicular Activity (EVA) Risk Standing Review Panel (SRP)

The Extravehicular Activity (EVA) Risk Standing Review Panel (SRP) was favorably impressed by the operational risk management approach taken by the Human Research Program (HRP) Integrated Research Plan (IRP) to address the stated life sciences issues. The life sciences community at the Johnson Space Center (JSC) seems to be focused on operational risk management. This approach is more likely to provide risk managers with the information they need at the time they need it. Concerning the information provided to the SRP by the EVA Physiology, Systems, and Performance Project (EPSP), it is obvious that a great deal of productive activity is under way. Evaluation of this information was hampered by the fact that it often was not organized in a fashion that reflects the "Gaps and Tasks" approach of the overall Human Health Countermeasures (HHC) effort, and that a substantial proportion of the briefing concerned subjects that, while interesting, are not part of the HHC Element (e.g., the pressurized rover presentation). Additionally, no information was provided on several of the tasks or how they related to work underway or already accomplished. This situation left the SRP having to guess at the efforts and relationship to other elements, and made it hard to easily map the EVA Project efforts currently underway, and the data collected thus far, to the gaps and tasks in the IRP. It seems that integration of the EPSP project into the HHC Element could be improved. Along these lines, we were concerned that our SRP was split off from the other participating SRPs at an early stage in the overall agenda for the meeting. In reality, the concerns of EPSP and other projects share much common ground. For example, the commonality of the concerns of the EVA and exercise physiology groups is obvious, both in terms of what reduced exercise capacity can do to EVA capability, and how the exercise performed during an EVA could contribute to an overall exercise countermeasure prescription.

Norfleet, William↗

NASA NTRS2014

Pratt and Whitney/Boeing Engine Validation of Noise Reduction Concepts: Final Report for NASA Contract NAS3-97144, Phase 1

Major airports in the world's air transportation systems face a serious problem in providing greater capacity to meet the ever increasing demands of air travel. This problem could be relieved if airports are allowed to increase their operating time, now restricted by curfews and by relaxing present limits on takeoffs and landings. The key operational issue in extending the present curfews is noise. In response to these increasing restrictive noise regulations, NASA has launched a program to validate through engine testing, noise reduction concepts and technologies that have evolved from the Advanced Subsonic Technologies (AST) Noise Reduction Program. The goal of this AST program was to develop and validate technology that reduces engine noise and improves nacelle suppression effectiveness relative to 1992 technology. Contract NAS3-97144 titled "Engine Validation of Noise Reduction Concepts" (EVNRC) was awarded to P&W on August 12, 1997 to conduct full scale noise reduction tests in two Phases on a PW4098 engine. The following Section 1.2 provides a brief description of the overall program. The remainder of this report provides a detailed documentation of Phase I of the program.

Mathews, Douglas↗

NASA NTRS1992

Update on Douglas' high-speed civil transport studies

A summary is presented of high speed civil transport (HSCT) studies underway at Douglas Aircraft. A brief review is given of experience with design and development of advanced supersonic transport concepts and associated technology. A review is then presented of past NASA funded contract research studies focused on selection of appropriate concepts for high speed civil transport aircraft to be introduced in the year 2000 time frame for commercial service. Follow-on activities to those studies are then presented which were conducted under independent research studies as well as under further NASA funded efforts. Design Mach number selections and associated baseline design missions are then discussed along with forecasted passenger traffic and associated supersonic fleet sizes, and then proceeds into a discussion of individual issues related either to environmental acceptability or overall technology requirements in order to achieve the required economic viability of the program. A summary is given of current and future plans and activities.

Bunin, Bruce L.↗

NASA NTRS1996

Report on Alternative Devices to Pyrotechnics on Spacecraft

Pyrotechnics accomplish many functions on today's spacecraft, possessing minimum volume/weight, providing instantaneous operation on demand, and requiring little input energy. However, functional shock, safety, and overall system cost issues, combined with emergence and availability of new technologies question their continued use on space missions. Upon request from the National Aeronautics and Space Administration's (NASA) Program Management Council (PMC), Langley Research Center (LaRC) conducted a survey to identify and evaluate state-of-the-art non-explosively actuated (NEA) alternatives to pyrotechnics, identify NEA devices planned for NASA use, and investigate potential interagency cooperative efforts. In this study, over 135 organizations were contacted, including NASA field centers, Department of Defense (DOD) and other government laboratories, universities, and American and European industrial sources resulting in further detailed discussions with over half, and 18 face-to-face briefings. Unlike their single use pyrotechnic predecessors, NEA mechanisms are typically reusable or refurbishable, allowing flight of actual tested units. NEAs surveyed include spool-based devices, thermal knife, Fast Acting Shockless Separation Nut (FASSN), paraffin actuators, and shape memory alloy (SMA) devices (e.g., Frangibolt). The electro-mechanical spool, paraffin actuator and thermal knife are mature, flight proven technologies, while SMA devices have a limited flight history. There is a relationship between shock, input energy requirements, and mechanism functioning rate. Some devices (e.g., Frangibolt and spool based mechanisms) produce significant levels of functional shock. Paraffin, thermal knife, and SMA devices can provide gentle, shock-free release but cannot perform critically timed, simultaneous functions. The FASSN flywheel-nut release device possesses significant potential for reducing functional shock while activating nearly instantaneously. Specific study recommendations include: (1) development of NEA standards, specifically in areas of material characterization, functioning rates, and test methods; (2) a systems level approach to assure successful NEA technology application; and (3) further investigations into user needs, along with industry/government system-level real spacecraft cost benefit trade studies to determine NEA application foci and performance requirements. Additional survey observations reveal an industry and government desire to establish partnerships to investigate remaining unknowns and formulate NEA standards, specifically those driven by SMAs. Finally, there is increased interest and need to investigate alternative devices for such functions as stage/shroud separation and high pressure valving. This paper summarizes results of the NASA-LaRC survey of pyrotechnic alternatives. State of-the-art devices with their associated weight and cost savings are presented. Additionally, a comparison of functional shock characteristics of several devices are shown, and potentially related technology developments are highlighted.

Lucy, M. H.↗

NASA NTRS2000

VCL Laser Altimeter Surface Return Expected Geolocation Performance

The Vegetation Canopy Lidar (VCL) mission, expected to launch in the spring of 2002, will carry a unique Multi-Beam Laser Altimeter (MBLA) instrument designed to observe vegetative canopy structure for a nominal mission duration of 2 years. The VCL MBLA is a three-beam instrument where each laser is capable of producing returns with 30-m along-track spacing and 25-m-diameter footprints. Identifying the precise location of the point on the Earth's surface from which the laser energy reflects is a critical issue in the validation and application of the data. The resultant geolocation accuracy is dependent on the performance of many components of the VCL system including: laser pulse round trip travel time observation to surface, navigation tracking data, attitude determination system data, timing, laser pointing and body orientation stability, knowledge of instrument and navigation tracking point positions, media and geophysical corrections. Additionally, it is critical to calibrate on-orbit instrument parameters including pointing and range corrections. The geolocation and calibration methodology and algorithms will be summarized. A detailed geolocation error analysis identifying the contributions from each system component, along with the resultant expected geolocation accuracy, will be presented. A brief discussion of the operational geolocation process will also be presented. Science and data validation implications from geolocation performance will be summarized.

Luthcke, S. B.↗

NASA NTRS1998

Summary of Proton Test on the Quick Logic QL3025 at Indiana University

This issue of the Programmable Logic Application Notes is a compilation of topics: (1) Proton irradiation tests were performed on the Quick Logic QL3025 at the Indian University Cyclotron facility. The devices, tests, and results are discussed; (2) The functional failure of EEPROM's in heavy ion environment is presented; (3) the Act 1 architecture is summarized; (4) Antifuse hardness and hardness testing is updated; the single even upset (SEU) response of hardwired flip-flops is also presented; (4) Total dose results of the ACT 2 and ACT 3 circuits is presented in a chart; (5) Recent sub-micron devices testing of total dose is presented in a chart along with brief discussion; and (6) a reference to the WWW site for more articles of interest.

Katz, Richard↗

NASA NTRS1997

Computer based imaging and analysis of root gravitropism

Two key issues in studies of the nature of the gravitropic response in roots have been the determination of the precise pattern of differential elongation responsible for downward bending and the identification of the cells that show the initial motor response. The main approach for examining patterns of differential growth during root gravitropic curvature has been to apply markers to the root surface and photograph the root at regular intervals during gravitropic curvature. Although these studies have provided valuable information on the characteristics of the gravitropic motor response in roots, their labor intensive nature limits sample size and discourages both high frequency of sampling and depth of analysis of surface expansion data. In this brief review we describe the development of computer-based video analysis systems for automated measurement of root growth and shape change and discuss some key features of the root gravitropic response that have been revealed using this methodology. We summarize the capabilities of several new pieces of software designed to measure growth and shape changes in graviresponding roots and describe recent progress in developing analysis systems for studying the small, but experimentally popular, primary roots of Arabidopsis. A key finding revealed by such studies is that the initial gravitropic response of roots of maize and Arabidopsis occurs in the distal elongation zone (DEZ) near the root apical meristem, not in the main elongation zone. Another finding is that the initiation of rapid elongation in the DEZ following gravistimulation appears to be related to rapid membrane potential changes in this region of the root. These observations have provided the incentive for ongoing studies examining possible links between potential growth modifying factors (auxin, calcium, protons) and gravistimulated changes in membrane potential and growth patterns in the DEZ.

NASA Discipline Plant Biology↗

NASA NTRS1997

An Approach to Building a Traceability Tool for Software Development

It is difficult in a large, complex computer program to ensure that it meets the specified requirements. As the program evolves over time, a11 program constraints originally elicited during the requirements phase must be maintained. In addition, during the life cycle of the program, requirements typically change and the program must consistently reflect those changes. Imagine the following scenario. Company X wants to develop a system to automate its assembly line. With such a large system, there are many different stakeholders, e.g., managers, experts such as industrial and mechanical engineers, and end-users. Requirements would be elicited from all of the stake holders involved in the system with each stakeholder contributing their point of view to the requirements. For example, some of the requirements provided by an industrial engineer may concern the movement of parts through the assembly line. A point of view provided by the electrical engineer may be reflected in constraints concerning maximum power usage. End-users may be concerned with comfort and safety issues, whereas managers are concerned with the efficiency of the operation. With so many points of view affecting the requirements, it is difficult to manage them, communicate information to relevant stakeholders. and it is likely that conflicts in the requirements will arise. In the coding process, the implementors will make additional assumptions and interpretations on the design and the requirements of the system. During any stage of development, stakeholders may request that a requirement be added or changed. In such a dynamic environment, it is difficult to guarantee that the system will preserve the current set of requirements. Tracing, the mapping between objects in the artifacts of the system being developed, addresses this issue. Artifacts encompass documents such as the system definition, interview transcripts, memoranda, the software requirements specification, user's manuals, the functional specifications, design reports, and system code. Tracing helps 1) validate system features against, the requirement specification, 2) identify error sources and, most importantly, 3) manage change. With so many people involved in the development of the system, it becomes necessary to identify the reasons behind the design requirements or the implementation decisions. This paper is concerned with an approach that maps documents to constraints that capture properties of and relationships between the objects being modeled by the program. Section 2 provides the reader with a background on traceability tools. Section 3 gives a brief description of the context monitoring system on which the approach suggested in this paper is based. Section 4 presents an overview of our approach to providing traceability. The last section presents our future direction of research.

Delgado, Nelly↗

NASA NTRS2000

Nonintrusive Diagnostic Strategies for Arcjet Stream Characterization

In the previous lecture, the issues related to arcjet flow modeling were introduced, and the limitations of conventional instrumentation in addressing these issues were discussed. The general level of understanding of the arcjet flows was seen to preclude the use of arcjets as aerothermodynamic test facilities beyond the current role in aerothermal material testing, despite their long test duration capability. In this section, the focus will be on new developments in spectroscopic instrumentation and techniques that can be brought to bear on the fundamental problem of arcjet stream characterization. Although a wide selection of arcjet facilities were introduced in the previous section, the discussion of nonintrusive diagnostic instrumentation will be restricted to the large-scale, segmented, constricted-arc heater facilities that are most widely used in thermal protection material testing for aerospace applications. After a brief review of the important features of arcjet flows, the topic of nonintrusive, optical diagnostics is introduced with a discussion of some of the basic aspects of radiative transitions. The lecture is then organized into two sections covering emission measurements and laser-induced fluorescence measurements. Emission measurements are presented next for different regions of arcjet flows, while the fluorescence measurements are presented for the free stream region only. Summaries are given for each of the two main sections, and observations on arcjet characterization by optical diagnostics in general are given at the end.

Fletcher, Douglas G.↗

NASA NTRS1986

Stellar and galactic jets - Theoretical issues

Theoretical issues pertaining to the modelling of jets in young stellar objects and in active galactic nuclei are reviewed. The strong morphological similarities between these two types of sources are emphasized, and observational constraints on the basic physical mechanisms that may be responsible for the jet phenomenon are outlined. Particular attention is given to the 'momentum-discharge problem' in molecular-cloud outflows and to its possible resolution in terms of a centrifugally driven magnetohydrodynamic wind from an accretion disk. In addition, various propagation effects are discussed, and the relevance to stellar jets of the de Laval collimation mechanism and of the accelerated-clump model for emission knots is assessed. The review concludes with a brief list of potentially useful observational tests.

Konigl, A.↗

NASA NTRS1993

Laser-based firing systems for prompt initiation of secondary explosives

Motivated by issues of weapon safety and security, laser based firing systems for promptly initiating secondary explosives have been under active development at Sandia National Laboratories for more than four years. Such a firing system consists of miniaturized, Q-switched, solid-state laser, optical detonators, optical safety switches, and elements for splitting, coupling, and transmitting the laser output. Potential system applications pose significant challenges in terms of server mechanical and thermal environments and packaging constraints, while requiring clear demonstration of safety enhancements. The Direct Optical Initiation (DOI) Program at Sandia is addressing these challenges through progress development phases during which the design, fabrication, and testing of prototype hardware is aimed at more difficult application requirements. A brief history of the development program, and a summary of current and planned activities, will be presented.

Meeks, Kent D.↗

NASA NTRS2005

Long-Range Emergency Preemption of Traffic Lights

A forwarding system could prove beneficial as an addition to an electronic communication-and-control system that automatically modifies the switching of traffic lights to give priority to emergency vehicles. A system to which the forwarding system could be added could be any of a variety of emergency traffic-signal-preemption systems: these include systems now used in some municipalities as well as advanced developmental systems described in several NASA Tech Briefs articles in recent years. Because of a variety of physical and design limitations, emergency traffic-signal- preemption systems now in use are often limited in range to only one intersection at a time: in a typical system, only the next, closest intersection is preempted for an emergency vehicle. Simulations of gridlock have shown that such systems offer minimal advantages and can even cause additional delays. In analogy to what happens in fluid dynamics, the forwarding system insures that flow at a given location is sustained by guaranteeing downstream flow along the predicted route (typically a main artery) and intersecting routes (typically, side streets). In simplest terms, the forwarding system starts by taking note of any preemption issued by the preemption system to which it has been added. The forwarding system predicts which other intersections could be encountered by the emergency vehicle downstream of the newly preempted intersection. The system then forwards preemption triggers to those intersections. Beyond affording a right of way for the emergency vehicle at every intersection that lies ahead along any likely route from the current position of the vehicle, the forwarding system also affords the benefit of clearing congested roads far ahead of the vehicle. In a metropolitan environment with heavy road traffic, forwarding of preemption triggers could greatly enhance the performance of a pre-existing preemption system.

Bachelder, Aaron↗

NASA NTRS1994

Intelsat solar array coupon atomic oxygen flight experiment

A Hughes communications satellite (INTELSAT series) belonging to the INTELSAT Organization was marooned in low-Earth orbit (LEO) on March 14, 1990, following failure of the Titan launch vehicle third stage to separate properly. The satellite, INTELSAT 6, was designed for service in geosynchronous orbit and contains several materials that are potentially susceptible to attack by atomic oxygen. Analysis showed that direct exposure of the silver interconnects in the satellite photovoltaic array to atomic oxygen in LEO was the key materials issue. Available data on atomic oxygen degradation of silver are limited and show high variance, so solar array configurations of the INTELSAT 6 type and individual interconnects were tested in ground-based facilities and during STS-41 (Space Shuttle Discovery, October 1990) as part of the ISAC flight experiment. Several materials for which little or no flight data exist were also tested for atomic oxygen reactivity. Dry lubricants, elastomers, and polymeric and inorganic materials were exposed to an oxygen atom fluence of 1.1 x 10(exp 20) atoms cm(exp 2). Many of the samples were selected to support Space Station Freedom design and decision making. This paper provides an overview of the ISAC flight experiment and a brief summary of results. In addition to new data on materials not before flown, ISAC provided data supporting the decision to rescue INTELSAT 6, which was successfully undertaken in May 1992.

TRT-GENERAL REVIEW↗

NASA NTRS1989

Galileo Mission Science Briefing

The first of two tapes of the Galileo Mission Science press briefing is presented. The panel is moderated by George Diller from the Kennedy Space Center (KSC) Public Affairs Office. The participants are John Conway, the director of Payload and operations at Kennedy; Donald E. Williams, Commander of STS-43, the shuttle mission which will launch the Galileo mission; John Casani, the Deputy Assistant Director of Flight Projects at the Jet Propulsion Lab (JPL); Dick Spehalski, Galileo Project Manager at JPL; and Terrence Johnson, Galileo Project Scientist at JPL. The briefing begins with an announcement of the arrival of the Galileo Orbiter at KSC. The required steps prior to the launch are discussed. The mission trajectory and gravity assists from planetary and solar flybys are reviewed. Detailed designs of the orbiter are shown. The distance that Galileo will travel from the sun precludes the use of solar energy for heat. Therefore Radioisotope heater units are used to keep the equipment at operational temperature. A video of the arrival of the spacecraft at KSC and final tests and preparations is shown. Some of the many science goals of the mission are reviewed. Another video showing an overview of the Galileo mission is presented. During the question and answer period, the issue of the use of plutonium on the mission is broached, which engenders a review of the testing methods used to ensure the safety of the capsules containing the hazardous substance. This video has actual shots of the orbiter, as it is undergoing the final preparations and tests for the mission.

Source record↗

NASA NTRS2016

MoonRIDERS: NASA and Hawaiis Innovative Lunar Surface Flight Experiment for Landing in Late 2017

Recently, NASA Kennedy Space Center, Hawaii's state aerospace agency PISCES, and two Hawaii high schools Iolani and Kealakehe have come together in a unique collaboration called MoonRIDERS. This strategic partnership will allow Hawaii students to participate directly in sending a science experiment to the surface of the moon. The MoonRIDERS project started in the spring of 2014, with each institution responsible for its own project costs and activities. PISCES, given its legislative direction in advancing planetary surface systems, saw this collaboration as an important opportunity to inspire a young generation and encourage STEM (Science, Technology, Engineering, and Mathematics) learning. Under the guidance of PISCES and NASA, the students will be involved hands-on from start to finish in the engineering, testing, and validation of a space technology called the Electrodynamic Dust Shield (EDS). Dust is a critical issue for space exploration, as evidenced by the Apollo lunar missions and Mars rovers and landers. Dust creates a number of problems for humans and hardware, including inhalation, mechanical interference, wear and tear on spacesuits, inhibition of heat transfer on radiators, and reduced efficiency of solar panels. To address this, the EDS is designed to work on a variety of materials, and functions by generatingelectrodynamic fields to clear away the dust. The Google Lunar XPRIZE (GLXP), a space competition "designed to inspire pioneers to do robotic space transport on a budget," serves as a likely method for the MoonRIDERS to get their project to the moon. The EDS would potentially be flown as a hosted payload on a competitor's lander (still to be chosen). This briefing will provide an overview of the technology, the unique partnership, progress update and testing leading to this flight opportunity.

Payload experiment↗