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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 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Magnetic flux transport of decaying active regions and enhanced magnetic network

Several series of coordinated observations on decaying active regions and enhanced magnetic network regions on the sun were carried out jointly at Big Bear Solar Observatory and at the Huairou Solar Observing Station of the Bejing Astronomical Observatory in China. The magnetic field evolution in several regions was followed closely for three to seven days. The magnetic flux transport from the remnants of decayed active regions was studied, along with the evolution and lifetime of the magnetic network which defines the boundaries of supergranules. The magnetic flux transport in an enhanced network region was studied in detail and found to be negative. Also briefly described are some properties of moving magnetic features around a sunspot. Results of all of the above studies are presented.

Wang, Haimin↗
NASA NTRS1991

The extraordinary 1989 December 14/15 optical flare events on V711 Tauri

Photometry in B and V taken with the Vanderbilt Tennessee State 16 inch (41 cm) robotic telescope confirms the intense broad-band optical continuum flare activity reported by Chinese observers on the active chromosphere binary V711 Tau on December 14/15, 1989. Twelve hours after the flare reported from China, there occurred a separate and more intense flare with B and V amplitudes of 0.69 and 0.42 mag, respectively. These amplitudes correspond to peak flare luminosities of approximately 2 x 10 to the 33rd ergs/s in B and 1 x 10 to the 33rd ergs/s in V. The observed color of its excess light implies that the flaring region covered approximately 8 percent of the surface of the K1 subgiant star on which it erupted. Although the shape of the light curve was unchanged after the flare, the mean brightness of the star was enhanced by 3 percent in B, and it required nearly three months to decay to its preflare mean brightness. This is the first confirmed and, by far, the brightest example of broad-band optical flaring activity on an evolved, magnetically active star more luminous than the sun.

Henry, Gregory W.↗
NASA NTRS1991

Research on inverse, hybrid and optimization problems in engineering sciences with emphasis on turbomachine aerodynamics: Review of Chinese advances

Advances in inverse design and optimization theory in engineering fields in China are presented. Two original approaches, the image-space approach and the variational approach, are discussed in terms of turbomachine aerodynamic inverse design. Other areas of research in turbomachine aerodynamic inverse design include the improved mean-streamline (stream surface) method and optimization theory based on optimal control. Among the additional engineering fields discussed are the following: the inverse problem of heat conduction, free-surface flow, variational cogeneration of optimal grid and flow field, and optimal meshing theory of gears.

Liu, Gao-Lian↗
NASA NTRS1991

Nonlinear optical polymers for electro-optic signal processing

Photonics is an emerging technology, slated for rapid growth in communications systems, sensors, imagers, and computers. Its growth is driven by the need for speed, reliability, and low cost. New nonlinear polymeric materials will be a key technology in the new wave of photonics devices. Electron-conjubated polymeric materials offer large electro-optic figures of merit, ease of processing into films and fibers, ruggedness, low cost, and a plethora of design options. Several new broad classes of second-order nonlinear optical polymers were developed at the Navy's Michelson Laboratory at China Lake, California. Polar alignment in thin film waveguides was achieved by electric-field poling and Langmuir-Blodgett processing. Our polymers have high softening temperatures and good aging properties. While most of the films can be photobleached with ultraviolet (UV) light, some have excellent stability in the 500-1600 nm range, and UV stability in the 290-310 nm range. The optical nonlinear response of these polymers is subpicosecond. Electro-optic switches, frequency doublers, light modulators, and optical data storage media are some of the device applications anticipated for these polymers.

Lindsay, Geoffrey A.↗
NASA NTRS1991

Fuzzy logic applications to expert systems and control

A considerable amount of work on the development of fuzzy logic algorithms and application to space related control problems has been done at the Johnson Space Center (JSC) over the past few years. Particularly, guidance control systems for space vehicles during proximity operations, learning systems utilizing neural networks, control of data processing during rendezvous navigation, collision avoidance algorithms, camera tracking controllers, and tether controllers have been developed utilizing fuzzy logic technology. Several other areas in which fuzzy sets and related concepts are being considered at JSC are diagnostic systems, control of robot arms, pattern recognition, and image processing. It has become evident, based on the commercial applications of fuzzy technology in Japan and China during the last few years, that this technology should be exploited by the government as well as private industry for energy savings.

Lea, Robert N.↗
NASA NTRS1992

Structural analysis of low-speed composite propfan blades for the LRCSW wind tunnel model

The Naval Weapons Center at China Lake, CA, is currently in the process of evaluating propulsion systems for the Long Range Conventional Standoff Weapons (LRCSW). At present, the Advanced Counter-Rotating Propfan system is being considered. The methodologies are documented which were used to structurally analyze the 0.55 scale CM1 composite propfan blades for the LRCSW with COBSTRAN and MSC/NASTRAN. Significant results are also reported.

Ernst, Michael A.↗
NASA NTRS1992

A Developing Multiple-wavelength Lidar for Detecting Mainly Ozone and Aerosol Distributions in the Stratosphere

A multiple wavelength lidar is being developed at the Institute of Atmospheric Physics, Beijing, China, for measuring mainly ozone and aerosol distributions in the stratosphere. The system is based on a Xecl excimer laser operating at 308nm and an Nd-YAG laser with three wavelengths of 1060nm, 532nm, and 355nm. The specifications of the lidar system are given in tabular form. The system is designed to measure the following parameters: 1) ozone vertical distribution (15-45km); 2) aerosol distribution (6-35km); 3) atmospheric temperature (30-70km); and 4) high clouds. The expected performances of the lidar system are simulated.

Zheng, Siping↗
NASA NTRS1992

The evolutionary development of high specific impulse electric thruster technology

Electric propulsion flight and technology demonstrations conducted primarily by Europe, Japan, China, the U.S., and the USSR are reviewed. Evolutionary mission applications for high specific impulse electric thruster systems are discussed, and the status of arcjet, ion, and magnetoplasmadynamic thrusters and associated power processor technologies are summarized.

Sovey, James S.↗
NASA NTRS1992

The 30th AAS Goddard Memorial Symposium. World space programs and fiscal reality: Synopsis

A full proceedings of the symposium will be issued later in the year. This synopsis consists of summations of three sessions by appointed rapporteurs. International figures in space and in politics spoke at the sessions. Themes of international cooperation and fiscal reality pervaded the conference. International speakers from Canada, the European Space Agency, Russia, Japan and China and other countries addressed the topic of the symposium. American representation included Senator Barbara Mikulski, former NASA administrator James Beggs and other speakers.

Source record↗
NASA NTRS1990

Nimbus 7 SMMR precipitation observations calibrated against surface radar during TAMEX

This paper compares recent (Petty and Katsaros, 1990) satellite passive microwave observations of tropical cloud clusters over the South China Sea, using the 37-GHz channels of the Nimbus-7 SMMR, to the surface digital radar observations of oceanic precipitation during the Taiwan Area Mesoscale Experiment (TAMEX) conducted in May and June, 1987 (Kuo and Chen, 1990). The data confirm the existence of useful statistical relationships between surface rainfall parameters and satellite microwave observations. It is suggested that the approach applied in this study can be expanded to include other microwave frequencies (for example, the 19- and 85-GHz channels of the SSM/I)

Petty, Grant W.↗
NASA NTRS1992

A data base describing low-gravity fluids and materials processing experiments

A data base documenting information on approximately 600 fluids and materials processing experiments performed in a low-gravity environment has been prepared at NASA Marshall Space Flight Center (MSFC). The compilation was designed to document all such experimental efforts performed: (1) on U.S. manned space vehicles; (2) on payloads deployed from U.S. manned space vehicles; and (3) on all domestic and international sounding rocket programs (excluding those of the U.S.S.R. and China). Identification of major (reported) sources of significant anomalies during 100 of the experiments is reported and discussed. Further, a preliminary summary of the number of these 100 investigations which experienced an anomaly affecting a certain percentage of the experimental results/objectives is presented.

Winter, C. A.↗
NASA NTRS1990

Convective and stratiform components of a Winter Monsoon Cloud Cluster determined from geosynchronous infrared satellite data

The horizontal precipitation structure of cloud clusters observed over the South China Sea during the Winter Monsoon Experiment (WMONEX) is analyzed using a convective-stratiform technique (CST) developed by Adler and Negri (1988). The technique was modified by altering the method for identifying convective cells in the satellite data, accounting for the extremely cold cloud tops characteristic of the WMONEX region, and modifying the threshold infrared temperature for the boundary of the stratiform rain area. The precipitation analysis was extended to the entire history of the cloud cluster by applying the modified CST to IR imagery from geosynchronous-satellite observations. The ship and aircraft data from the later period of the cluster's lifetime make it possible to check the locations of convective and stratiform precipitation identified by the CST using in situ observations. The extended CST is considered to be effective for determining the climatology of the convective-stratiform structure of tropical cloud clusters.

Goldenberg, Stanley B.↗
NASA NTRS1991

The great Chinese fire of 1987 - A view from space

One of the largest forest fires ever recorded burned in the People's Republic of China (PRC) and the Soviet Union in May 1987. The fire covered over 1.0 million hectares in the PRC and almost 4 million hectares in the Soviet Union. The progress and areal extent of the fire were measured using satellite images analyzed in the imaging facilities at NASA-Langley and Forestry Canada. The analyses show the utility and value of satellite measurements to assess the areal extent and geographical distribution of fires, and have important implications for future measurements to be obtained from space platforms, such as the Earth Observing System.

Cahoon, Donald R., Jr.↗
NASA NTRS1992

The evolutionary development of high specific impulse electric thruster technology

Electric propulsion flight and technology demonstrations conducted in the USA, Europe, Japan, China, and USSR are reviewed with reference to the major flight qualified electric propulsion systems. These include resistojets, ion thrusters, ablative pulsed plasma thrusters, stationary plasma thrusters, pulsed magnetoplasmic thrusters, and arcjets. Evolutionary mission applications are presented for high specific impulse electric thruster systems. The current status of arcjet, ion, and magnetoplasmadynamic thrusters and their associated power processor technologies are summarized.

Sovey, James S.↗
NASA NTRS1991

Fiber optic and laser sensors VIII; Proceedings of the Meeting, San Jose, CA, Sept. 17-19, 1990

This issue presents topics on the advances in fiber-optic sensor technology, fiber-optic gyroscope, fiber-optic position and pressure sensors, fiber-optic magnetic and temperature sensors, and generic fiber-optic sensors. Papers included are on a novel analog phase tracker for interferometric fiber-optic sensor applications, recent development status of fiber-optic sensors in China, the magnetic-field sensitivity of depolarized fiber-optic gyros, a depolarized fiber-optic gyro for future tactical applications, fiber-optic position transducers for aircraft controls, and a metal embedded optical-fiber pressure sensor. Attention is also given to a fiber-optic magnetic field sensor using spectral modulation encoding, a bare-fiber temperature sensor, an interferometric fiber-optic accelerometer, improvement of specular reflection pyrometer, a theoretical analysis of two-mode elliptical-core optical fiber sensors, and a fiber probe for ring pattern.

Depaula, Ramon P.↗
NASA NTRS1992

Calculations of surface radiation in arid regions - A case study

The surface and satellite data measured during the preliminary field experiment for the Land-Atmosphere Interactions Experiment conducted at the Heihe River basin in western China are used to investigate the difficulties encountered in the derivation of the surface radiation budget in arid regions. The surface radiation is derived by coupling theoretical radiative transfer calculations with satellite cloud retrievals. For cloud-free cases, the modeled downward solar fluxes are systematically larger than the measured fluxes. It is found that the error can be reduced and that good agreement between the computed and measured surface solar fluxes can be obtained by using an aerosol single-scattering albedo of 0.5 and an optical thickness of about 0.2 in the afternoon hours. For all the cases studied when both surface and satellite data are available, the mean errors are 4.3 and -4.7 W/sq m for the net downward surface solar flux and the downward surface IR flux, respectively. The rms errors are 17.4 and 22.1 W/sq m for the respective surface fluxes. The importance of aerosols in surface radiation calculations is underscored.

Chou, Ming-Dah↗
NASA NTRS1992

U.S. international initiatives in orbital debris

The paper discusses NASA's efforts in international cooperation in the field of orbital debris research, primarily since 1989. Cooperative activities and coordination with ESA, Germany, France, Russia, Japan, and China are described. Plans for future directions in cooperation are outlined.

Jacobs, Daniel V.↗
NASA NTRS1992

Hong Kong is an impact crater: Proof from the geomorphological and geological evidence

Hong Kong is a city in southern China. The urban districts of Hong Kong, Kowloon, and Victoria Harbour are situated within Hong Kong. Hong Kong is surrounded by mountains with a diameter of 11 km. Three million people live inside the basin. The round structure of the mountains in Hong Kong has been describd as a granite dome that is deeply eroded (batholith). The circularity of the mountains, the existence of a central hill, the inner slope of the mountains being greater than the outer slope, the presence of deep layer rock inside the basin, and the depth-to-diameter ratio were studied. All this evidence shows that the Hong Kong structure satisfies the geomorphological requirement of an impact crater. Some shock metamorphic phenomena of the rocks in Hong Kong such as planar features, microspherilitic silica glass (lechaterlierite), fused margins of rock fragments, concussion fractures, impact glass in which some schlierens are consistent with pyroxene spiculites, etc., were first discovered in Oct. 1990. In Hong Kong Island, an impact melt sheet was observed from the Victoria Peak to the southern shore. Quenching fractures of quartz in Kowloon fine-grained granite was also discovered. In our work, the K-Ar age (83.34 + 1.26 m.y.) of the impact melt rock, which is younger in comparison to the K-Ar age (117 m.y.) in Hong Kong and Kowloon granite, was measured, and the phenomena indicate that after the granite body formed, there was another geologic event. Maybe it is the Hong Kong cratering event.

Chan, Chu-Lok↗