SEARCH · Search NASA

Results for “small scale processes”

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 469 records · Page 26

All sources NASA NTRS DOE OSTI

NASA NTRS1999

Production and Characterization of Carbon Nanotubes and Nanotube-Based Composites

The Nobel Prize winning discovery of the Buckuball (C60) in 1985 at Rice University by a group including Dr. Richard Smalley led to the whole new class of carbon allotropes including fullerenes and nanotubes. Especially interesting from many viewpoints are single-walled carbon nanotubes, which structurally are like a single graphitic sheet wrapped around a cylinder and capped at the ends. This cylinders have diameter as small as 0.5 - 2 nm (1/100,000th the diameter of a human hair) and are as long as 0.1 - 1 mm. Nanotubes are really individual molecules and believed to be defect-free, leading to high tensile strength despite their low density. Additionally, these fibers exhibit electrical conductivity as high as copper, thermal conductivity as high as diamond, strength 100 times higher than steel at one-sixth the weight, and high strain to failure. Thus it is believed that developments in the field of nanotechnology will lead to stronger and lighter composite materials for next generation spacecraft. Lack of a bulk method of production is the primary reason nanotubes are not used widely today. Toward this goal JSC nanotube team is exploring three distinct production techniques: laser ablation, arc discharge and chemical vapor deposition (CVD, in collaboration with Rice University). In laser ablation technique high-power laser impinges on the piece of carbon containing small amount of catalyst, and nanotubes self-assemble from the resulting carbon vapor. In arc generator similar vapor is created in arc discharge between carbon electrodes with catalyst. In CVD method nanotubes grow at much lower temperature on small catalyst particles from carbon-containing feedstock gas (methane or carbon monoxide). As of now, laser ablation produces cleanest material, but mass yield is rather small. Arc discharge produces grams of material, but purity is low. CVD technique is still in baby steps, but preliminary results look promising, as well as perspective of scaling the process up. We are also working on necessary purification of nanotubes. Applications of nanotubes are in such various fields as lightweight composites, molecular electronics, energy storage (electrodes in Li ion batteries), flat panel displays, conductive polymers, etc. JSC nanotube team is focused on development of lightweight materials. We work on the injection thermoset epoxies reinforced with nanotubes. Early results show good wetting of nanotube surface with epoxy, which is very important. More research will be possible as more nanotubes become available.

Nikolaev, Pavel↗

NASA NTRS2005

The Flow of Plasma in the Solar-Terrestrial Environment

The overall goal of our NASA theory research is to trace the flow of mass, momentum, and energy through the magnetosphere-ionosphere-atmosphere system taking into account the coupling, time delays, and feedback mechanisms that are characteristic of the system. Our approach is to model the magnetosphere-ionosphere-atmosphere (M-I-A) system in a self-consistent quantitative manner using unique global models that allow us to study the coupling between the different regions on a range of spatial and temporal scales. The uniqueness of our global models stems from their high spatial and temporal resolutions, the physical processes included, and the numerical techniques employed. Currently, we have time-dependent global models of the ionosphere, thermosphere, polar wind, plasmasphere, and electrodynamics. It is now becoming clear that a significant fraction of the flow of mass, momentum, and energy in the M-I-A system occurs on relatively small spatial scales. Therefore, an important aspect of our NASA Theory program concerns the effect that mesoscale (100-l000 km) density structures have on the macroscopic flows in the ionosphere, thermosphere, and polar wind. The structures can be created either by structured magnetospheric inputs (i.e., structured electric field, precipitation, or Birkeland current patterns) or by time variations of these inputs due to geomagnetic storms and substorms. Some of the mesoscale structures of interest include sun-aligned polar cap arcs, propagating plasma patches, traveling convection vortices, subauroral ion drift (SAID) channels, gravity waves, and the polar hole.

Schunk, Robert W.↗

NASA NTRSDate not supplied

Tailoring Early Concept Maturity Levels for Small Satellite Missions

The Concept Maturity Level (CML) framework has gained widespread acceptance as a process to assess mission concept maturity, particularly for early mission concepts in the formulation phase. Popularized by the Jet Propulsion Laboratory almost 15 years ago to evaluate large NASA science mission concepts, the CML method offers wide-ranging programmatic and technical evaluation criteria to assess and measure the progress of mission concepts at all stages of maturity. It also provides a useful tool to facilitate stakeholder relationships through effective engagement, interaction, and communication. The CML approach is modeled largely after the widespread Technology Readiness Level (TRL) scale, a measure of how new technology progresses from early concept through to being operational at the mission flight system level. Tailoring the CML framework for small satellites allows for more relevant technical and programmatic evaluations for these missions. Given the diversity of small satellite mission objectives, cost constraints, complexity, and risk tolerance, this modified CML framework enables study teams and stakeholders to determine the appropriate CML fidelity to implement based upon the opportunity and strategic investment approach. A decision process flow method is proposed to guide teams through the logic of determining what CML fidelity to implement in evaluating small satellite mission concepts. The goal is to provide enhanced stakeholder engagement such that CML assessments are clearly articulated and understood early in the design study. This would allow for more appropriate application of CML methodology by study teams developing University led missions, technology demonstrations, commercial constellations, and more complex planetary science missions.

Concept Maturity Level↗

DOE OSTI2024

Electricity use in big area additive manufacturing of fiber-reinforced polymer composites

In recent years, additive manufacturing (AM), especially large-format additive manufacturing (LFAM), has gained momentum in the manufacturing industry. While LFAM offers benefits over conventional manufacturing processes, such as minimizing material waste and providing vast geometric freedom, assessing its sustainability remains challenging due to limited data, particularly on energy consumption. Most existing data pertain to small-scale or desktop AM and are not directly applicable to LFAM. In this study, we conducted real-time measurements of electricity usage for a type of LFAM known as big area additive manufacturing (BAAM), which typically uses fiber-reinforced polymer pellets as feedstock. We collected electricity usage data from fifteen printing jobs over two months in an industrial production setting. These data fill the existing gap and can be reused to enhance the community’s understanding of LFAM electricity usage, support further research, and promote sustainable development in advanced manufacturing technologies.

ecology↗

NASA NTRS1977

Size distribution of particles in planetary rings

Harris (1975) has suggested that the maximum size of particles in a planetary ring is controlled by collisional fragmentation rather than tidal stress. While this conclusion is probably true, estimated radius limits must be revised upward from Harris' values of a few kilometers by at least an order of magnitude. Accretion of particles within the Roche limit is also possible. These considerations affect theories concerning the evolution of Saturn's rings, of the moon, and of possible former satellites of Mercury and Venus. In the case of Saturn's rings, comparison of various theoretical scenarios with available observational evidence suggests that the rings formed from the breakup of larger particles rather than from original condensation as small particles. This process implies a distribution of particle sizes in Saturn's rings possibly ranging up to about 100 km but with most of the cross section in centimeter-scale particles.

Greenberg, R.↗

NASA NTRS1982

Evidence for the three-stage cooling history of olivine-porphyritic fluid droplet chondrules

A three-stage model for the cooling of olivine-porphyritic fluid droplet chondrules found in ordinary chondrites is proposed, in light of an experimental examination of three haplochondritic melts to determine thermal parameters in a pre-accretionary chondrule environment. The model encompasses: (1) initial continuous cooling from at least liquidus temperatures, at 300-4000 C/hour, to about 1300 C, over approximately 5-60 min; (2) interruption of the initial cooling by a short-duration isothermal event at about 1300 C; and (3) quenching. This thermal model, in which the entire history of fluid droplet chondrules is only a brief process in the early history of the solar system, suggests a specific and restricted physical origin for chondrules which is not likely to have been achieved by such repetitive, small-scale events as planetary surface impact splattering or volcanism. A single, large-scale event is postulated.

Planner, H. N.↗

NASA NTRS1986

Radar investigation of asteroids

The number of radar detected asteroids has climbed from 6 to 40 (27 mainbelt plus 13 near-Earth). The dual-circular-polarization radar sample now comprises more than 1% of the numbered asteroids. Radar results for mainbelt asteroids furnish the first available information on the nature of these objects at macroscopic scales. At least one object (2 Pallas) and probably many others are extraordinarily smooth at centimeter-to-meter scales but are extremely rough at some scale between several meters and many kilometers. Pallas has essentially no small-scale structure within the uppermost several meters of the regolith, but the rms slope of this regolith exceeds 20 deg., much larger than typical lunar values (approx. 7 deg.). The origin of these slopes could be the hypervelocity impact cratering process, whose manifestations are likely to be different on low-gravity, low-radius-of-curvature objects from those on the terrestrial planets. The range of mainbelt asteroid radar albedoes is very broad and implies big variations in regolith porosity or metal concentration, or both. The highest albedo estimate, for 16 Psyche, is consistent with a surface having porosities typical of lunar soil and a composition nearly completely metallic. Therefore, Psyche might be the collisionally stripped core of a differentiated small plant, and might resemble mineralogically the parent bodies of iron meteorites.

Ostro, S. J.↗

NASA NTRS1989

Measurement of vertical velocity using clear-air Doppler radars

A new clear air Doppler radar was constructed, called the Flatland radar, in very flat terrain near Champaign-Urbana, Illinois. The radar wavelength is 6.02 m. The radar has been measuring vertical velocity every 153 s with a range resolution of 750 m almost continuously since March 2, 1987. The variance of vertical velocity at Flatland is usually quite small, comparable to the variance at radars located near rough terrain during periods of small background wind. The absence of orographic effects over very flat terrain suggests that clear air Doppler radars can be used to study vertical velocities due to other processes, including synoptic scale motions and propagating gravity waves. For example, near rough terrain the shape of frequency spectra changes drastically as the background wind increases. But at Flatland the shape at periods shorter than a few hours changes only slowly, consistent with the changes predicted by Doppler shifting of gravity wave spectra. Thus it appears that the short period fluctuations of vertical velocity at Flatland are alsmost entirely due to the propagating gravity waves.

Vanzandt, T. E.↗

NASA NTRS2011

Low Cost Nuclear Thermal Rocket Cermet Fuel Element Environment Testing

Deep space missions with large payloads require high specific impulse (Isp) and relatively high thrust in order to achieve mission goals in reasonable time frames. Conventional, storable propellants produce average Isp. Nuclear thermal rockets (NTR) capable of high Isp thrust have been proposed. NTR employs heat produced by fission reaction to heat and therefore accelerate hydrogen which is then forced through a rocket nozzle providing thrust. Fuel element temperatures are very high (up to 3000K) and hydrogen is highly reactive with most materials at high temperatures. Data covering the effects of high temperature hydrogen exposure on fuel elements is limited. The primary concern is the mechanical failure of fuel elements which employ high-melting-point metals, ceramics or a combination (cermet) as a structural matrix into which the nuclear fuel is distributed. It is not necessary to include fissile material in test samples intended to explore high temperature hydrogen exposure of the structural support matrices. A small-scale test bed designed to heat fuel element samples via non-contact RF heating and expose samples to hydrogen is being developed to assist in optimal material and manufacturing process selection without employing fissile material. This paper details the test bed design and results of testing conducted to date.

Bradley, David E.↗

NASA NTRS2016

A Model for Straight and Helical Solar Jets: II. Parametric Study of the Plasma Beta

Context. Jets are dynamic, impulsive, well-collimated plasma events that develop at many different scales and in different layers of the solar atmosphere. Aims. Jets are believed to be induced by magnetic reconnection, a process central to many astrophysical phenomena. Within the solar atmosphere, jet-like events develop in many different environments, e.g. in the vicinity of active regions as well as in coronal holes, and at various scales, from small photospheric spicules to large coronal jets. In all these events, signatures of helical structure and/or twisting/rotating motions are regularly observed. The present study aims to establish that a single model can generally reproduce the observed properties of these jet-like events. Methods. In this study, using our state-of-the-art numerical solver ARMS, we present a parametric study of a numerical tridimensional magnetohydrodynamic (MHD) model of solar jet-like events. Within the MHD paradigm, we study the impact of varying the atmospheric plasma beta on the generation and properties of solar-like jets. Results. The parametric study validates our model of jets for plasma beta ranging from 10(sup 3) to 1, typical of the different layers and magnetic environments of the solar atmosphere. Our model of jets can robustly explain the generation of helical solar jet-like events at various beta less than or equal to 1. We show that the plasma beta modifies the morphology of the helical jet, explaining the different observed shapes of jets at different scales and in different layers of the solar atmosphere. Conclusions. Our results allow us to understand the energisation, triggering, and driving processes of jet-like events. Our model allows us to make predictions of the impulsiveness and energetics of jets as determined by the surrounding environment, as well as the morphological properties of the resulting jets.

Magnetic Field↗

NASA NTRS1983

Electronic Force Gage for Welders

Welding force monitored in process. Electronic force gage uses strain gage on deformable member. Oscilloscope trace of welding force photographed and compared with standard trace during calibration and troubleshooting of resistance welding equipment. Adaptable to small scale resistance welding in electronics industry.

Bradley, J. W.↗

NASA NTRS1982

Opportunities for composites in commercial transport structures

Manufacturers are developing composite versions of structural components on existing aircraft. Development involves testing of various material options before selecting one and then extensive testing to develop an adequate data base of material strength and stiffness properties. Design options are narrowed through analysis and a varied spectrum of development tests on small and large subcomponents. In parallel with this, a suitable production process including economical ply preparation and cure at high temperature and pressure is evolved, tools are designed and fabricated, and full scale components are then manufactured for ground qualification tests, flight tests, and airline service. The various tests include many that are required by the FAA for flight certification, which must precede airline service. Inspection and repair methods to insure adequate maintenance in service are also developed.

Herman L. Bohon↗

NASA NTRS1988

Automatic line generalization using zero-crossings

The problem of automating the process of line generalization has been very difficult. It has not been solved yet despite the concerted effort of many private firms as well as government agencies. There does not exist an algorithm which can automatically perform this process when there is a drastic change in scale between the original and generalized maps. In this paper, an algorithm which is successful in automatically generalizing lines from any large scale to any small scale is presented. The algorthm achieves different levels of smoothing the line while preserving the overall shape of the line. The results are compared with those obtained by manual methods. It was found that the results obtained by the algorithm are very close to those obtained by cartographers using manual methods.

Thapa, K.↗

NASA NTRS1991

Production of solar photovoltaic cells on the Moon

Solar energy is directly available on the sunward lunar surface. Most, if not all, the materials are available on the Moon to make silicon based solar photovoltaic cells. A few additional types are possible. There is a small but growing literature on production of lunar derived solar cells. This literature is reviewed. Topics explored include trade-offs of local production versus import of key materials, processing options, the scale and nature of production equipment, implications of storage requirements, and the end-uses of the energy. Directions for future research and demonstrations are indicated.

Criswell, David R.↗

NASA NTRS2000

Magnetic Flux Compression Concept for Nuclear Pulse Propulsion and Power

The desire for fast, efficient interplanetary transport requires propulsion systems having short acceleration times and very high specific impulse attributes. Unfortunately, most highly efficient propulsion systems which are within the capabilities of present day technologies are either very heavy or yield very low impulse such that the acceleration time to final velocity is too long to be of lasting interest, One exception, the nuclear thermal thruster, could achieve the desired acceleration but it would require inordinately large mass ratios to reach the range of desired final velocities. An alternative approach, among several competing concepts that are beyond our modern technical capabilities, is a pulsed thermonuclear device utilizing microfusion detonations. In this paper, we examine the feasibility of an innovative magnetic flux compression concept for utilizing microfusion detonations, assuming that such low yield nuclear bursts can be realized in practice. In this concept, a magnetic field is compressed between an expanding detonation driven diamagnetic plasma and a stationary structure formed from a high temperature superconductor (HTSC). In general, we are interested in accomplishing two important functions: (1) collimation of a hot diamagnetic plasma for direct thrust production; and (2) pulse power generation for dense plasma ignition. For the purposes of this research, it is assumed that rnicrofusion detonation technology may become available within a few decades, and that this approach could capitalize on recent advances in inertial confinement fusion ICF) technologies including magnetized target concepts and antimatter initiated nuclear detonations. The charged particle expansion velocity in these detonations can be on the order of 10 (exp 6)- 10 (exp 7) meters per second, and, if effectively collimated by a magnetic nozzle, can yield the Isp and the acceleration levels needed for practical interplanetary spaceflight. The ability to ignite pure fusion micro-bursts with reasonable levels of input energy is an equally challenging scientific problem. It remains to be seen, however, whether an effective ignition driver can be developed which meets the requirements for practical spaceflight application (namely high power density, compactness, low weight, and low cost). In this paper, system level performance and design issues are examined including generator performance, magnetic flux compression processes, magnetic diffusion processes, high temperature superconductor (HTSC) material properties, plasmadynamic processes, detonation plasma expansion processes, magnetohydrodynamic instabilities, magnetic nozzle performance, and thrust production performance. Representative generator performance calculations based on a simplified skin layer formulation are presented as well as the results of exploratory small-scale laboratory experiments on magnetic flux diffusion in HTSC materials. In addition, planned follow-on scientific feasibility experiments are described which utilize high explosive detonations and high energy gas discharges to simulate the plasma conditions associated with thermonuclear micro-detonations.

Litchford, Ronald J.↗

NASA NTRS1981

Sampling problems: The small scale structure of precipitation

The quantitative measurement of precipitation characteristics for any area on the surface of the Earth is not an easy task. Precipitation is rather variable in both space and time, and the distribution of surface rainfall data given location typically is substantially skewed. There are a number of precipitation process at work in the atmosphere, and few of them are well understood. The formal theory on sampling and estimating precipitation appears considerably deficient. Little systematic attention is given to nonsampling errors that always arise in utilizing any measurement system. Although the precipitation measurement problem is an old one, it continues to be one that is in need of systematic and careful attention. A brief history of the presently competing measurement technologies should aid us in understanding the problem inherent in this measurement task.

Crane, R. K.↗

DOE OSTI2024

Enabling high-throughput enzyme discovery and engineering with a low-cost, robot-assisted pipeline

Abstract As genomic databases expand and artificial intelligence tools advance, there is a growing demand for efficient characterization of large numbers of proteins. To this end, here we describe a generalizable pipeline for high-throughput protein purification using small-scale expression in E. coli and an affordable liquid-handling robot. This low-cost platform enables the purification of 96 proteins in parallel with minimal waste and is scalable for processing hundreds of proteins weekly per user. We demonstrate the performance of this method with the expression and purification of the leading poly(ethylene terephthalate) hydrolases reported in the literature. Replicate experiments demonstrated reproducibility and enzyme purity and yields (up to 400 µg) sufficient for comprehensive analyses of both thermostability and activity, generating a standardized benchmark dataset for comparing these plastic-degrading enzymes. The cost-effectiveness and ease of implementation of this platform render it broadly applicable to diverse protein characterization challenges in the biological sciences.

36 MATERIALS SCIENCE↗

NASA NTRS1973

Characteristics of a gelled liquid hyprogen polyphenylene oxide (PPO) foam open-cell insulation system, phase 1

A large scale gel production and storage facility and a small scale facility, the latter used for detailed visual examination of the gel/PPO foam interface, were developed. A subcontract was given to investigate techniques for the production of gelled liquid hydrogen, develop a process design for scale-up to a 1.89 cu m (500 gallon) gel production and storage facility, determine gel transfer characteristics, determine the solubility rate of gaseous helium in the gel, and investigate the gross gel/PPO foam interfacial phenomena. An inside-tank process for scaled-up production of gelled liquid hydrogen was selected. No detectable gel structure degradation occurred during repeated shearing. The viscosity of gelled liquid hydrogen at shear rates of 300/sec and higher is 2 to 5-fold greater than that of neat liquid hydrogen. No clogging problems were encountered during the transfer of gelled liquid hydrogen through warmed transfer lines. The solubility rate of helium in liquid hydrogen was significantly reduced by the presence of gel structure. The boil-off rates from gelled liquid hydrogen were reduced from 25 to 50 percent compared to those observed for the neat liquid hydrogen under compatible conditions. The polyphenylene oxide (PPO) foam insulation was found to be compatible with liquid ethane.

Source record↗