Influence of Agricultural Practice on Surface Temperature

NASA Astrophysics Data System (ADS)

Czajkowski, K.; Ault, T.; Hayase, R.; Benko, T.

2006-12-01

Changes in land uses/covers can have a significant effect on the temperature of the Earth's surface. Agricultural fields exhibit a significant change in land cover within a single year and from year to year as different crops are planted. These changes in agricultural practices including tillage practice and crop type influence the energy budget as reflected in differences in surface temperature. In this project, Landsat 5 and 7 imagery were used to investigate the influence of crop type and tillage practice on surface temperature in Iowa and NW Ohio. In particular, the three crop rotation of corn, soybeans and wheat, as well as no-till, conservation tillage and tradition tillage methods, were investigated. Crop type and conservation tillage practices were identified using supervised classification. Student surface temperature observations from the GLOBE program were used to correct for the effects of the atmosphere for some of the satellite thermal observations. Students took surface temperature observations in field sites near there schools using hand- held infrared thermometers.

Topoclimatological survey of Switzerland

NASA Technical Reports Server (NTRS)

Winiger, M. (Principal Investigator)

1982-01-01

The application of Heat Capacity Mapping Mission data to subsynoptic climate analysis of Switzerland was examined. The data included the surface temperature distributions of urban heat islands and the Swiss Alps. Analog and digital data evaluation procedures are described as well as the ground truth acquisition and comparison program. The dependence of the temperature distributions on topography and surface coverage types is assessed. The results indicate that air temperature inversion zones are detectable.

Botswana water and surface energy balance research program. Part 1: Integrated approach and field campaign results

NASA Technical Reports Server (NTRS)

Vandegriend, A. A.; Owe, M.; Vugts, H. F.; Ramothwa, G. K.

1992-01-01

The Botswana water and surface energy balance research program was developed to study and evaluate the integrated use of multispectral satellite remote sensing for monitoring the hydrological status of the Earth's surface. Results of the first part of the program (Botswana 1) which ran from 1 Jan. 1988 - 31 Dec. 1990 are summarized. Botswana 1 consisted of two major, mutually related components: a surface energy balance modeling component, built around an extensive field campaign; and a passive microwave research component which consisted of a retrospective study of large scale moisture conditions and Nimbus scanning multichannel microwave radiometer microwave signatures. The integrated approach of both components in general are described and activities performed during the surface energy modeling component including the extensive field campaign are summarized. The results of the passive microwave component are summarized. The key of the field campaign was a multilevel approach, whereby measurements by various similar sensors were made at several altitudes and resolution. Data collection was performed at two adjacent sites of contrasting surface character. The following measurements were made: micrometeorological measurements, surface temperatures, soil temperatures, soil moisture, vegetation (leaf area index and biomass), satellite data, aircraft data, atmospheric soundings, stomatal resistance, and surface emissivity.

Real-time observation of coadsorption layers on Ru(001) using a temperature-programmed ESDIAD/TOF system

NASA Astrophysics Data System (ADS)

Sasaki, T.; Itai, Y.; Iwasawa, Y.

1997-11-01

For the purpose of utilizing ESDIAD as a real-time probe for surface processes, we have developed an instrument which can measure ESDIAD images and time of flight (TOF) spectra of desorbing ions in temperature-programmed surface processes. TOF measurements are carried out to identify the mass and to determine the kinetic energy distribution of the desorbed ions. This temperature-programmed (TP-) ESDIAD/TOF system was used to observe coadsorption layers of methylamine and CO on Ru(001) which have been previously studied by our group using LEED, TPD and HREELS, also drawing upon a comparison of findings with the coadsorption system of CO and ammonia. ESDIAD images acquired for temperature-programmed surface processes in real time were found to provide new insight into the dynamic behaviour of the coadsorption layers. As to the pure adsorption of ammonia and methylamine, the second and the first (chemisorbed) layers can be easily discriminated in their different ESD detection efficiency due to the difference in neutralization rate. The intensity change of H + ions with temperature shows the process of the decomposition of methylamine to be dependent on CO coverage. The intensity of O + originating from CO changes due to the change of CO adsorption site in the reaction process. The angular distribution of H + ions which correspond to CH2NH…Ru species appears at 250-300 K in the presence of high CO pre-coverage.

Use of GLOBE Observations to Derive a Landsat 8 Split Window Algorithm for Urban Heat Island

NASA Astrophysics Data System (ADS)

Fagerstrom, L.; Czajkowski, K. P.

2017-12-01

Surface temperature has been studied to investigate the warming of urban climates, also known as urban heat islands, which can impact urban planning, public health, pollution levels, and energy consumption. However, the full potential of remotely sensed images is limited when analyzing land surface temperature due to the daunting task of correcting for atmospheric effects. Landsat 8 has two thermal infrared sensors. With two bands in the infrared region, a split window algorithm (SWA), can be applied to correct for atmospheric effects. This project used in situ surface temperature measurements from NASA's ground observation program, the Global Learning and Observations to Benefit the Environment (GLOBE), to derive the correcting coefficients for use in the SWA. The GLOBE database provided land surface temperature data that coincided with Landsat 8 overpasses. The land surface temperature derived from Landsat 8 SWA can be used to analyze for urban heat island effect.

Surface studies of water isotopes in Antarctica for quantitative interpretation of deep ice core data

NASA Astrophysics Data System (ADS)

Landais, Amaelle; Casado, Mathieu; Prié, Frédéric; Magand, Olivier; Arnaud, Laurent; Ekaykin, Alexey; Petit, Jean-Robert; Picard, Ghislain; Fily, Michel; Minster, Bénédicte; Touzeau, Alexandra; Goursaud, Sentia; Masson-Delmotte, Valérie; Jouzel, Jean; Orsi, Anaïs

2017-07-01

Polar ice cores are unique climate archives. Indeed, most of them have a continuous stratigraphy and present high temporal resolution of many climate variables in a single archive. While water isotopic records (δD or δ18O) in ice cores are often taken as references for past atmospheric temperature variations, their relationship to temperature is associated with a large uncertainty. Several reasons are invoked to explain the limitation of such an approach; in particular, post-deposition effects are important in East Antarctica because of the low accumulation rates. The strong influence of post-deposition processes highlights the need for surface polar research programs in addition to deep drilling programs. We present here new results on water isotopes from several recent surface programs, mostly over East Antarctica. Together with previously published data, the new data presented in this study have several implications for the climatic reconstructions based on ice core isotopic data: (1) The spatial relationship between surface mean temperature and mean snow isotopic composition over the first meters in depth can be explained quite straightforwardly using simple isotopic models tuned to d-excess vs. δ18O evolution in transects on the East Antarctic sector. The observed spatial slopes are significantly higher (∼ 0.7-0.8‰·°C-1 for δ18O vs. temperature) than seasonal slopes inferred from precipitation data at Vostok and Dome C (0.35 to 0.46‰·°C-1). We explain these differences by changes in condensation versus surface temperature between summer and winter in the central East Antarctic plateau, where the inversion layer vanishes in summer. (2) Post-deposition effects linked to exchanges between the snow surface and the atmospheric water vapor lead to an evolution of δ18O in the surface snow, even in the absence of any precipitation event. This evolution preserves the positive correlation between the δ18O of snow and surface temperature, but is associated with a much slower δ18O-vs-temperature slope than the slope observed in the seasonal precipitation. (3) Post-deposition effects clearly limit the archiving of high-resolution (seasonal) climatic variability in the polar snow, but we suggest that sites with an accumulation rate of the order of 40 kg.m-2.yr-1 may record a seasonal cycle at shallow depths.

Advanced High Temperature Structural Seals

NASA Astrophysics Data System (ADS)

Newquist, Charles W.; Verzemnieks, Juris; Keller, Peter C.; Rorabaugh, Michael; Shorey, Mark

2002-10-01

This program addresses the development of high temperature structural seals for control surfaces for a new generation of small reusable launch vehicles. Successful development will contribute significantly to the mission goal of reducing launch cost for small, 200 to 300 pound payloads. Development of high temperature seals is mission enabling. For instance, ineffective control surface seals can result in high temperature (3100 F) flows in the elevon area exceeding structural material limits. Longer sealing life will allow use for many missions before replacement, contributing to the reduction of hardware, operation and launch costs.

Advanced High Temperature Structural Seals

NASA Technical Reports Server (NTRS)

Newquist, Charles W.; Verzemnieks, Juris; Keller, Peter C.; Rorabaugh, Michael; Shorey, Mark

2002-01-01

This program addresses the development of high temperature structural seals for control surfaces for a new generation of small reusable launch vehicles. Successful development will contribute significantly to the mission goal of reducing launch cost for small, 200 to 300 pound payloads. Development of high temperature seals is mission enabling. For instance, ineffective control surface seals can result in high temperature (3100 F) flows in the elevon area exceeding structural material limits. Longer sealing life will allow use for many missions before replacement, contributing to the reduction of hardware, operation and launch costs.

Modified Ni-Cu catalysts for ethanol steam reforming

NASA Astrophysics Data System (ADS)

Dan, M.; Mihet, M.; Almasan, V.; Borodi, G.; Katona, G.; Muresan, L.; Lazar, M. D.

2013-11-01

Three Ni-Cu catalysts, having different Cu content, supported on γ-alumina were synthesized by wet co-impregnation method, characterized and tested in the ethanol steam reforming (ESR) reaction. The catalysts were characterized for determination of: total surface area and porosity (N2 adsorption - desorption using BET and Dollimer Heal methods), Ni surface area (hydrogen chemisorption), crystallinity and Ni crystallites size (X-Ray Diffraction), type of catalytic active centers (Hydrogen Temperature Programmed Reduction). Total surface area and Ni crystallites size are not significantly influenced by the addition of Cu, while Ni surface area is drastically diminished by increasing of Cu concentration. Steam reforming experiments were performed at atmospheric pressure, temperature range 150-350°C, and ethanol - water molar ration of 1 at 30, using Ar as carrier gas. Ethanol conversion and hydrogen production increase by the addition of Cu. At 350°C there is a direct connection between hydrogen production and Cu concentration. Catalysts deactivation in 24h time on stream was studied by Transmission Electron Microscopy (TEM) and temperature-programmed reduction (TPR) on used catalysts. Coke deposition was observed at all studied temperatures; at 150°C amorphous carbon was evidenced, while at 350°C crystalline, filamentous carbon is formed.

Structural and surface properties of CuO-ZnO-Cr{sub 2}O{sub 3} catalysts and their relationship with selectivity to higher alcohol synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campos-Martin, J.M.; Fierro, J.L.G.; Guerrero-Ruiz, A.

1995-10-01

A series of copper-zinc-chromium catalysts of different compositions and calcination temperatures has been prepared, characterized by several techniques (BET specific surface area, XRD, gravimetric TPR, TPD-CO, and XPS), and tested under high alcohol synthesis (HAS) conditions. CO hydrogenation was carried out at reaction temperatures of 523-598 K and 50 bar total pressure. The influence of catalyst composition, calcination temperature, and surface characteristics on the HAS selectivity was studied. The optimum HAS yields were found in the low Cr content region, but chromium was needed. Although chromium oxide does not seem to be involved in the catalytic site, its presence inmore » the catalyst composition is essential, owing to the larger specific surfaces and catalyst stability obtained at the highest reaction temperatures. For low Cr content composition, the temperature-programmed reduction (TPR) profiles were shifted to higher temperatures and simultaneously larger CO{sub 2} amounts were found in the temperature-programmed desorption profiles of adsorbed CO (TPD-CO). Photoelectron spectra (XPS) revealed that the oxidation state of copper is Cu{sup 2+} in the calcined catalysts and Cu{sup O} in the reduced ones; Cu{sup +} was only stabilized in a CuCr{sub 2}O{sub 4} spinel in the Cr-rich catalysts. These features derived from catalyst characterization are discussed in the framework of the catalytic behaviour for HAS synthesis. 53 refs., 7 figs., 4 tabs.« less

Thermal transformation of bioactive caffeic acid on fumed silica seen by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry and quantum chemical methods.

PubMed

Kulik, Tetiana V; Lipkovska, Natalia O; Barvinchenko, Valentyna M; Palyanytsya, Borys B; Kazakova, Olga A; Dudik, Olesia O; Menyhárd, Alfréd; László, Krisztina

2016-05-15

Thermochemical studies of hydroxycinnamic acid derivatives and their surface complexes are important for the pharmaceutical industry, medicine and for the development of technologies of heterogeneous biomass pyrolysis. In this study, structural and thermal transformations of caffeic acid complexes on silica surfaces were studied by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry (TPD MS) and quantum chemical methods. Two types of caffeic acid surface complexes are found to form through phenolic or carboxyl groups. The kinetic parameters of the chemical reactions of caffeic acid on silica surface are calculated. The mechanisms of thermal transformations of the caffeic chemisorbed surface complexes are proposed. Thermal decomposition of caffeic acid complex chemisorbed through grafted ester group proceeds via three parallel reactions, producing ketene, vinyl and acetylene derivatives of 1,2-dihydroxybenzene. Immobilization of phenolic acids on the silica surface improves greatly their thermal stability. Copyright © 2016 Elsevier Inc. All rights reserved.

Development of sensors for ceramic components in advanced propulsion systems: Survey and evaluation of measurement techniques for temperature, strain and heat flux for ceramic components in advanced propulsion systems

NASA Technical Reports Server (NTRS)

Atkinson, W. H.; Cyr, M. A.; Strange, R. R.

1988-01-01

The report presents the final results of Tasks 1 and 2, Development of Sensors for Ceramic Components in Advanced Propulsion Systems (NASA program NAS3-25141). During Task 1, an extensive survey was conducted of sensor concepts which have the potential for measuring surface temperature, strain and heat flux on ceramic components for advanced propulsion systems. Each sensor concept was analyzed and evaluated under Task 2; sensor concepts were then recommended for further development. For temperature measurement, both pyrometry and thermographic phosphors are recommended for measurements up to and beyond the melting point of ceramic materials. For lower temperature test programs, the thin-film techniques offer advantages in the installation of temperature sensors. Optical strain measurement techniques are recommended because they offer the possibility of being useful at very high temperature levels. Techniques for the measurement of heat flux are recommended for development based on both a surface mounted sensor and the measurement of the temperature differential across a portion of a ceramic component or metallic substrate.

The reactions of thiophene on Mo(110) and Mo(110)-p(2×2)-S

NASA Astrophysics Data System (ADS)

Roberts, Jeffrey T.; Friend, C. M.

1987-07-01

The reactions of thiophene and 2,5-dideuterothiophene on Mo(110) and Mo(110)-p(2×2)-S have been investigated under ultrahigh vacuum conditions using temperature programmed reaction spectroscopy and Auger electron spectroscopy. Thiophene chemisorbed on Mo(110) decomposes during temperature programmed reaction to yield only gaseous dihydrogen, surface carbon, and surface sulfur. At low thiophene exposures, dihydrogen evolves from Mo(110) in a symmetric peak at 440 K. At saturation exposures, three dihydrogen peaks are detected at 360 K, at 420 K and at 565 K. Multilayers of thiophene desorb at 180 K. Temperature programmed reaction of 2,5-dideuterothiophene demonstrates that at high thiophene coverages, one of the α-C-H bonds (those nearest sulfur) breaks first. No bond breaking selectivity is observed at low thiophene exposures. The Mo(110)-p(2×2)-S surface is less active for thiophene decomposition. Thiophene adsorbed on Mo(110)-p(2×2)-S to low coverages decomposes to surface carbon surface sulfur, and hydrogen at 430 K. At reaction saturation, dihydrogen production is observed at 375 and 570 K. In addition, at moderate and high exposures, chemisorbed thiophene desorbs from Mo(110)-p(2×2)-S. At saturation the desorption temperature of the reversibly chemisorbed state is 215 K. Experiments with 2,5-dideuterothiophene demonstrate no surface selectivity for α-C-H bond breaking reactions on Mo(110)-p(2×2)-S. The decomposition mechanism and energetics of thiophene decomposition are proposed to be dependent on the coverage of thiophene. At low thiophene exposures, the ring is proposed to bond parallel to the surface. All C-H bonds in the parallel geometry are sterically available for activation by the surface, accounting for the lack of selectivity in C-H bond breaking. High thiophene coverages are suggested to result in perpendicularly bound thiophene which undergoes selective α-dehydrogenation to an α)-thiophenyl intermediate. The presence of sulfur leads to a high energy pathway for cleavage of C-H bonds in a thiophene derived intermediate. Carbon-hydrogen bonds survive on the surface up to temperatures of 650 K. Comparison of this study with work on Mo(100) demonstrates that the reaction of thiophene on molybdenum is relatively insensitive to the surface geometric structure.

An atlas of monthly mean distributions of GEOSAT sea surface height, SSMI surface wind speed, AVHRR/2 sea surface temperature, and ECMWF surface wind components during 1988

NASA Technical Reports Server (NTRS)

Halpern, D.; Zlotnicki, V.; Newman, J.; Brown, O.; Wentz, F.

1991-01-01

Monthly mean global distributions for 1988 are presented with a common color scale and geographical map. Distributions are included for sea surface height variation estimated from GEOSAT; surface wind speed estimated from the Special Sensor Microwave Imager on the Defense Meteorological Satellite Program spacecraft; sea surface temperature estimated from the Advanced Very High Resolution Radiometer on NOAA spacecrafts; and the Cartesian components of the 10m height wind vector computed by the European Center for Medium Range Weather Forecasting. Charts of monthly mean value, sampling distribution, and standard deviation value are displayed. Annual mean distributions are displayed.

Adsorption and Reaction of Acetaldehyde on Shape-Controlled CeO2 Nanocrystals: Elucidation of Structure-function Relationships

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mann, Amanda K; Wu, Zili; Calaza, Florencia

2014-01-01

CeO2 cubes with {100} facets, octahedra with {111} facets, and wires with highly defective structures were utilized to probe the structure-dependent reactivity of acetaldehyde. Using temperature-programmed desorption (TPD), temperature-programmed surface reactions (TPSR), and in situ infrared spectroscopy it was found that acetaldehyde desorbs unreacted or undergoes reduction, coupling, or C-C bond scission reactions depending on the surface structure of CeO2. Room temperature FTIR indicates that acetaldehyde binds primarily as 1-acetaldehyde on the octahedra, in a variety of conformations on the cubes, including coupling products and acetate and enolate species, and primarily as coupling products on the wires. The percent consumptionmore » of acetaldehyde follows the order of wires > cubes > octahedra. All the nanoshapes produce the coupling product crotonaldehyde; however, the selectivity to produce ethanol follows the order wires cubes >> octahedra. The selectivity and other differences can be attributed to the variation in the basicity of the surfaces, defects densities, coordination numbers of surface atoms, and the reducibility of the nanoshapes.« less

Multicolor pyrometer for materials processing in space, phase 2

NASA Technical Reports Server (NTRS)

Frish, Michael; Frank, Jonathan; Beerman, Henry

1988-01-01

The program goals were to design, construct, and program a prototype passive imaging pyrometer capable of measuring, as accurately as possible, the temperature distribution across the surface of a moving object suspended in space.

Real-time observation of the dehydrogenation processes of methanol on clean Ru(001) and Ru(001)-p(2×2) O surfaces by a temperature-programmed electron-stimulated desorption ion angular distribution/time-of-flight system

NASA Astrophysics Data System (ADS)

Sasaki, Takehiko; Itai, Yuichiro; Iwasawa, Yasuhiro

1999-12-01

Decomposition processes of methanol on clean and oxygen-precovered Ru(001) surfaces have been visualized in real time with a temperature-programmed (TP) electron-stimulated desorption ion angular distribution (ESDIAD)/time-of-flight (TOF) system. The mass of desorbed ions during temperature-programmed surface processes was identified by TOF measurements. In the case of methanol (CH 3OD) adsorption on Ru(001)-p(2×2)-O, a halo pattern of H + from the methyl group of methoxy species was observed at 100-200 K, followed by a broad pattern from the methyl group at 230-250 K and by a near-center pattern from O + ions originating from adsorbed CO above 300 K. The halo pattern is attributed to a perpendicular conformation of the CO bond axis of the methoxy species, leading to off-normal CH bond scission. On the other hand, methanol adsorbed on clean Ru(001) did not give any halo pattern but a broad pattern was observed along the surface normal, indicating that the conformation of the methoxy species is not ordered on the clean surface. Comparison between the ESDIAD images of the oxygen-precovered surface and the clean surface suggests that the precovered oxygen adatoms induce ordering of the methoxy species. Real-time ESDIAD measurements revealed that the oxygen atoms at the Ru(001)-p(2×2)-O surface have a positive effect on selective dehydrogenation of the methoxy species to CO+H 2 and a blocking effect on CO bond breaking of the methoxy species.

Effect of non-equilibrium flow chemistry and surface catalysis on surface heating to AFE

NASA Technical Reports Server (NTRS)

Stewart, David A.; Henline, William D.; Chen, Yih-Kanq

1991-01-01

The effect of nonequilibrium flow chemistry on the surface temperature distribution over the forebody heat shield on the Aeroassisted Flight Experiment (AFE) vehicle was investigated using a reacting boundary-layer code. Computations were performed by using boundary-layer-edge properties determined from global iterations between the boundary-layer code and flow field solutions from a viscous shock layer (VSL) and a full Navier-Stokes solution. Surface temperature distribution over the AFE heat shield was calculated for two flight conditions during a nominal AFE trajectory. This study indicates that the surface temperature distribution is sensitive to the nonequilibrium chemistry in the shock layer. Heating distributions over the AFE forebody calculated using nonequilibrium edge properties were similar to values calculated using the VSL program.

In situ supported MnOx-CeOx on carbon nanotubes for the low-temperature selective catalytic reduction of NO with NH3

NASA Astrophysics Data System (ADS)

Zhang, Dengsong; Zhang, Lei; Shi, Liyi; Fang, Cheng; Li, Hongrui; Gao, Ruihua; Huang, Lei; Zhang, Jianping

2013-01-01

The MnOx and CeOx were in situ supported on carbon nanotubes (CNTs) by a poly(sodium 4-styrenesulfonate) assisted reflux route for the low-temperature selective catalytic reduction (SCR) of NO with NH3. X-Ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD) have been used to elucidate the structure and surface properties of the obtained catalysts. It was found that the in situ prepared catalyst exhibited the highest activity and the most extensive operating-temperature window, compared to the catalysts prepared by impregnation or mechanically mixed methods. The XRD and TEM results indicated that the manganese oxide and cerium oxide species had a good dispersion on the CNT surface. The XPS results demonstrated that the higher atomic concentration of Mn existed on the surface of CNTs and the more chemisorbed oxygen species exist. The H2-TPR results suggested that there was a strong interaction between the manganese oxide and cerium oxide on the surface of CNTs. The NH3-TPD results demonstrated that the catalysts presented a larger acid amount and stronger acid strength. In addition, the obtained catalysts exhibited much higher SO2-tolerance and improved the water-resistance as compared to that prepared by impregnation or mechanically mixed methods.The MnOx and CeOx were in situ supported on carbon nanotubes (CNTs) by a poly(sodium 4-styrenesulfonate) assisted reflux route for the low-temperature selective catalytic reduction (SCR) of NO with NH3. X-Ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD) have been used to elucidate the structure and surface properties of the obtained catalysts. It was found that the in situ prepared catalyst exhibited the highest activity and the most extensive operating-temperature window, compared to the catalysts prepared by impregnation or mechanically mixed methods. The XRD and TEM results indicated that the manganese oxide and cerium oxide species had a good dispersion on the CNT surface. The XPS results demonstrated that the higher atomic concentration of Mn existed on the surface of CNTs and the more chemisorbed oxygen species exist. The H2-TPR results suggested that there was a strong interaction between the manganese oxide and cerium oxide on the surface of CNTs. The NH3-TPD results demonstrated that the catalysts presented a larger acid amount and stronger acid strength. In addition, the obtained catalysts exhibited much higher SO2-tolerance and improved the water-resistance as compared to that prepared by impregnation or mechanically mixed methods. Electronic supplementary information (ESI) available: SEM images and EDS analysis, TEM images, and XPS spectrum of samples. See DOI: 10.1039/c2nr33006g

Soil temperature investigations using satellite acquired thermal-infrared data in semi-arid regions. Thesis. Final Report; [Utah

NASA Technical Reports Server (NTRS)

Day, R. L.; Petersen, G. W.

1983-01-01

Thermal-infrared data from the Heat Capacity Mapping Mission satellite were used to map the spatial distribution of diurnal surface temperatures and to estimate mean annual soil temperatures (MAST) and annual surface temperature amplitudes (AMP) in semi-arid east central Utah. Diurnal data with minimal snow and cloud cover were selected for five dates throughout a yearly period and geometrically co-registered. Rubber-sheet stretching was aided by the WARP program which allowed preview of image transformations. Daytime maximum and nighttime minimum temperatures were averaged to generation average daily temperature (ADT) data set for each of the five dates. Five ADT values for each pixel were used to fit a sine curve describing the theoretical annual surface temperature response as defined by a solution of a one-dimensinal heat flow equation. Linearization of the equation produced estimates of MAST and AMP plus associated confidence statistics. MAST values were grouped into classes and displayed on a color video screen. Diurnal surface temperatures and MAST were primarily correlated with elevation.

Atmospheric model development in support of SEASAT. Volume 2: Analysis models

NASA Technical Reports Server (NTRS)

Langland, R. A.

1977-01-01

As part of the SEASAT program of NASA, two sets of analysis programs were developed for the Jet Propulsion Laboratory. One set of programs produce 63 x 63 horizontal mesh analyses on a polar stereographic grid. The other set produces 187 x 187 third mesh analyses. The parameters analyzed include sea surface temperature, sea level pressure and twelve levels of upper air temperature, height and wind analyses. The analysis output is used to initialize the primitive equation forecast models.

Computer-Generated Phase Diagrams for Binary Mixtures.

ERIC Educational Resources Information Center

Jolls, Kenneth R.; And Others

1983-01-01

Computer programs that generate projections of thermodynamic phase surfaces through computer graphics were used to produce diagrams representing properties of water and steam and the pressure-volume-temperature behavior of most of the common equations of state. The program, program options emphasizing thermodynamic features of interest, and…

Temperature-programmed desorption study of NO reactions on rutile TiO2(110)-1×1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Boseong; Dohnálek, Zdenek; Szanyi, János

2016-10-01

Systematic temperature-programmed desorption (TPD) studies of NO adsorption and reactions on rutile TiO2(110)-1×1 surface reveal several distinct reaction channels in a temperature range of 50 – 500 K. NO readily reacts on TiO2(110) to form N2O which desorbs between 50 and 200 K (LT N2O channels), which leaves the TiO2 surface populated with adsorbed oxygen atoms (Oa) as a byproduct of N2O formation. In addition, we observe simultaneous desorption peaks of NO and N2O at 270 K (HT1 N2O) and 400 K (HT2 N2O), respectively, both of which are attributed to reaction-limited processes. No N-derived reaction product desorbs from TiO2(110)more » surface above 500 K or higher, while the surface may be populated with Oa’s and oxidized products such as NO2 and NO3. The adsorbate-free TiO2 surface with oxygen vacancies can be regenerated by prolonged annealing at 850 K or higher. Detailed analysis of the three N2O desorption yields reveals that the surface species for the HT channels are likely to be various forms of NO dimers.« less

Temperature-programmed desorption study of NO reactions on rutile TiO 2(110)-1×1

DOE PAGES

Kim, Boseong; Dohnalek, Zdenek; Szanyi, Janos; ...

2016-02-24

In this study, systematic temperature-programmed desorption (TPD) studies of NO adsorption and reactions on rutile TiO 2(110)-1 × 1 surface reveal several distinct reaction channels in a temperature range of 50–500 K. NO readily reacts on TiO 2(110) to form N 2O, which desorbs between 50 and 200 K (LT N 2O channels), which leaves the TiO 2 surface populated with adsorbed oxygen atoms (O a) as a by-product of N 2O formation. In addition, we observe simultaneous desorption peaks of NO and N 2O at 270 K (HT1 N 2O) and 400 K (HT2 N 2O), respectively, both ofmore » which are attributed to reaction-limited processes. No N-derived reaction product desorbs from TiO 2(110) surface above 500 K or higher, while the surface may be populated with Oa's and oxidized products such as NO 2 and NO 3. The adsorbate-free TiO 2 surface with oxygen vacancies can be regenerated by prolonged annealing at 850 K or higher. Detailed analysis of the three N 2O desorption yields reveals that the surface species for the HT channels are likely to be various forms of NO dimers.« less

A preview of a modular surface light scattering instrument with autotracking optics

NASA Technical Reports Server (NTRS)

Meyer, William V.; Tin, Padetha; Mann, J. Adin, Jr.; Cheung, H. Michael; Rogers, Richard B.; Lading, Lars

1994-01-01

NASA's Advanced Technology Development (ATD) program is sponsoring the development of a new generation of surface light scattering hardware. This instrument is designed to non-invasively measure the surface response function of liquids over a wide range of operating conditions while automatically compensating for a sloshing surface. The surface response function can be used to compute surface tension, properties of monolayers present, viscosity, surface tension gradient and surface temperature. The instrument uses optical and electronic building blocks developed for the laser light scattering program at NASA Lewis along with several unique surface light scattering components. The emphasis of this paper is the compensation for bulk surface motion (slosh). Some data processing background information is also included.

Coadsorbed species explain the mechanism of methanol temperature-desorption on CeO 2(111)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sutton, Jonathan E.; Steven H. Overbury; Beste, Ariana

2016-03-24

Here, we have used density functional theory calculations to investigate the temperature-programmed desorption (TPD) of methanol from CeO 2(111). For the first time, low-temperature water formation and high-temperature methanol desorption are explained by our calculations. High coverages of methanol, which correspond to experimental conditions, are required to properly describe these features of the TPD spectrum. We identify a mechanism for the low-temperature formation of water involving the dissociation of two methanol molecules on the same surface O atom and filling of the resulting surface vacancy with one of the methoxy products. After water desorption, methoxy groups are stabilized on themore » surface and react at higher temperatures to form methanol and formaldehyde by a disproportionation mechanism. Alternatively, the stabilized methoxy groups undergo sequential C–H scission reactions to produce formaldehyde. Calculated energy requirements and methanol/formaldehyde selectivity agree with the experimental data.« less

Symmetric Imidazolium-Based Paramagnetic Ionic Liquids

DTIC Science & Technology

2017-11-29

REPORT DATE 2. REPORT TYPE 3 . DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER...ADDRESS(ES) 12. DISTRIBUTION/AVAILABILITY STATEMENT 13. SUPPLEMENTARY NOTES 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: a...Number: 17717 3 Motivation •SLIPS at high temperatures •ILs: stable at high temperatures but high surface tension •Alkyl chains to reduce surface tension

Computer programs for thermodynamic and transport properties of hydrogen (tabcode-II)

NASA Technical Reports Server (NTRS)

Roder, H. M.; Mccarty, R. D.; Hall, W. J.

1972-01-01

The thermodynamic and transport properties of para and equilibrium hydrogen have been programmed into a series of computer routines. Input variables are the pair's pressure-temperature and pressure-enthalpy. The programs cover the range from 1 to 5000 psia with temperatures from the triple point to 6000 R or enthalpies from minus 130 BTU/lb to 25,000 BTU/lb. Output variables are enthalpy or temperature, density, entropy, thermal conductivity, viscosity, at constant volume, the heat capacity ratio, and a heat transfer parameter. Property values on the liquid and vapor boundaries are conveniently obtained through two small routines. The programs achieve high speed by using linear interpolation in a grid of precomputed points which define the surface of the property returned.

Segregation effects during solidification in weightless melts

NASA Technical Reports Server (NTRS)

Li, C.; Gershinsky, M.

1974-01-01

The generalized problem of determining the temperature and solute concentration profiles during directional solidification of binary alloys with surface evaporation was mathematically formulated. Realistic initial and boundary conditions were defined, and a computer program was developed and checked out. The programs computes the positions of two moving boundaries, evaporation and solidification, and their velocities. Temperature and solute concentration profiles in the semiinfinite material body at selected instances of time are also computed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, Sean W., E-mail: sean.king@intel.com; Davis, Robert F.; Carter, Richard J.

The desorption kinetics of molecular hydrogen (H{sub 2}) from silicon (001) surfaces exposed to aqueous hydrogen fluoride and remote hydrogen plasmas were examined using temperature programmed desorption. Multiple H{sub 2} desorption states were observed and attributed to surface monohydride (SiH), di/trihydride (SiH{sub 2/3}), and hydroxide (SiOH) species, subsurface hydrogen trapped at defects, and hydrogen evolved during the desorption of surface oxides. The observed surface hydride species were dependent on the surface temperature during hydrogen plasma exposure with mono, di, and trihydride species being observed after low temperature exposure (150 °C), while predominantly monohydride species were observed after higher temperature exposure (450 °C).more » The ratio of surface versus subsurface H{sub 2} desorption was also found to be dependent on the substrate temperature with 150 °C remote hydrogen plasma exposure generally leading to more H{sub 2} evolved from subsurface states and 450 °C exposure leading to more H{sub 2} desorption from surface SiH{sub x} species. Additional surface desorption states were observed, which were attributed to H{sub 2} desorption from Si (111) facets formed as a result of surface etching by the remote hydrogen plasma or aqueous hydrogen fluoride treatment. The kinetics of surface H{sub 2} desorption were found to be in excellent agreement with prior investigations of silicon surfaces exposed to thermally generated atomic hydrogen.« less

Scanning Tunneling Microscopy Study of Carbon Tetrachloride Adsorption and Degradation on a Natural a-Fe2O3(0001) Surface in Ultrahigh Vacuum

NASA Astrophysics Data System (ADS)

Taeg Rim, Kwang; Fitts, Jeffrey; Adib, Kaveh; Camillone, Nicholas, III; Schlosser, Peter; Osgood, Richard, Jr.; Flynn, George; Joyce, Stephen

2001-03-01

Scanning tunneling microscopy and low energy electron diffraction have been used to study a natural a-Fe2O3(0001) surface and the adsorption and degradation of carbon tetrachloride on the reduced Fe3O4(111) terminated surface. A natural a-Fe2O3 (0001) surface was prepared by repeated cycles of Ar+ ion sputtering and annealing in vacuum or in O2 at 850 K. STM images and a LEED pattern indicate that an Fe3O4(111) terminated surface and a bi-phase can be formed depending on annealing conditions. The Fe3O4(111) terminated surface was dosed with CCl4 at room temperature, and flashed up to 590 K and 850 K. STM images show adsorbates on the surface at room temperature and the degradation products of CCl4 are isolated on the surface as the flashing temperature increases up to 850 K. Results from a companion temperature programmed desorption investigation are used in conjunction with the STM images to propose site specific reactions of CCl4 on the Fe3O4(111) terminated surface.

The FEI-TPS on the Upper Surface of the X-38

NASA Astrophysics Data System (ADS)

Antonenko, Johann; Kowal, John

2002-01-01

The X-38 is being developed by NASA-JSC as a technology demonstrator of a future Crew Rescue Vehicle. The size of the vehicle is limited to fit into the cargo bay of the shuttle. Due to its small size and shuttle-like trajectory all surfaces will receive comparably high heat rates leading to high surface temperatures. Temperatures on the nose are calculated to reach 1750°C, which is significantly higher than on the shuttle. Due to the lifting body shape, large areas of the central fuselage will be exposed to flow of hot gases around the vehicle. Here temperatures of the upper surface are calculated to reach up to 1000°C and the application of a high temperature blanket thermal protection system (TPS) becomes mandatory. Consecutively, the temperature level of the upper surface and the base area will be significantly high. Unlike on the shuttle, where large areas of the surface are covered by flexible reusable surface insulation (FRSI), locations with temperatures below 400°C will be scarce on the X-38. During development of the European shuttle HERMES the Flexible External Insulation (FEI) was developed for the upper surface TPS. This development was continued by ESA and DLR funded programs and currently a product family is available for temperatures ranging from 450°C to 1100°C for re-usable application. For a single re- entry under ultimate conditions temperatures may reach up to 1400°C. Under funding of DLR and ESA, the FEI assembly is one of the European contributions to the X-38. Three subassemblies have been chosen: the FEI-450, FEI-650 and FEI- 1000, capable of limit temperatures of 450°C, 650°C and 1000°C, respectively. The FEI-650 and FEI-1000 were already developed in the HERMES program. The FEI- 450 was developed in the German TETRA program. The qualification for X-38 application was performed for temperatures up to 510°C for the FEI-450 and up to 1130°C for the FEI-1000. Acoustic noise loads of up to 160dB have been endured, far beyond what X-38 will ever experience. The paper presents the design of the flexible blanket TPS in a joint effort by NASA-JSC and Astrium. The design process at NASA had to consider aerothermal loads and constraints of the structure and parachute subsystems. It provided the configuration of the FEI assembly and the requirements design of the FEI blankets. Astrium first designed the concept and lay-out of the FEI-assembly. Proceeding from NASA furnished model files, the design to manufacturing of the FEI-blankets was established. In addition, Astrium qualified the FEI for X-38 application. The FEI design is constrained by the aeroshell concept that distinguishes acreage panels, carrier panels and close-out areas, with dedicated blankets for each. Close out areas cover the locations of the parafoil system and create an uneven surface requiring vaulted blankets. The total of these requirements leads to an assembly of a large number of blankets, several of which have a complex shape.

Performance Simulation of a Flat-Plate Thermoelectric Module Consisting of Square Truncated Pyramid Elements

NASA Astrophysics Data System (ADS)

Oki, Sae; Suzuki, Ryosuke O.

2017-05-01

The performance of a flat-plate thermoelectric (TE) module consisting of square truncated pyramid elements is simulated using commercial software and original TE programs. Assuming that the temperatures of both the hot and cold surfaces are constant, the performance can be varied by changing the element shape and element alignment pattern. When the angle between the edge and the base is 85° and the small square surfaces of all n-type element faces are connected to the low-temperature surface, the efficiency becomes the largest among all the 17 examined shapes and patterns. By changing the shape to match the temperature distribution, the performance of the TE module is maximized.

Mathematical model of the metal mould surface temperature optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mlynek, Jaroslav, E-mail: jaroslav.mlynek@tul.cz; Knobloch, Roman, E-mail: roman.knobloch@tul.cz; Srb, Radek, E-mail: radek.srb@tul.cz

2015-11-30

The article is focused on the problem of generating a uniform temperature field on the inner surface of shell metal moulds. Such moulds are used e.g. in the automotive industry for artificial leather production. To produce artificial leather with uniform surface structure and colour shade the temperature on the inner surface of the mould has to be as homogeneous as possible. The heating of the mould is realized by infrared heaters located above the outer mould surface. The conceived mathematical model allows us to optimize the locations of infrared heaters over the mould, so that approximately uniform heat radiation intensitymore » is generated. A version of differential evolution algorithm programmed in Matlab development environment was created by the authors for the optimization process. For temperate calculations software system ANSYS was used. A practical example of optimization of heaters locations and calculation of the temperature of the mould is included at the end of the article.« less

Temperature-dependent Study of Isobutanol Decomposition

DTIC Science & Technology

2012-11-01

dimensional Al2O3 alumina CO2 carbon dioxide FTIR Fourier transform infrared Pd palladium Rh rhodium TPD temperature-programmed desorption TPO...that increasing temperature promotes aldehyde formation on the surface of each catalyst. In addition, it is shown that palladium (Pd) activates the...formation of aldehydes and CO2 at a lower temperature than a rhodium (Rh) catalyst. 15. SUBJECT TERMS Isobutanol, FTIR, spectroscopy 16. SECURITY

Strong Temperature Dependence in the Reactivity of H 2 on RuO 2 (110)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henderson, Michael A.; Dahal, Arjun; Dohnálek, Zdenek

2016-08-04

The ability of hydrogen to facilitate many types of heterogeneous catalysis starts with its adsorption. As such, understanding the temperature-dependence sticking of H2 is critical toward controlling and optimizing catalytic conditions in those cases where adsorption is rate-limiting. In this work, we examine the temperature-dependent sticking of H2/D2 to the clean RuO2(110) surface using the King & Wells molecular beam approach, temperature programmed desorption (TPD) and scanning tunneling microscopy (STM). We show that the sticking probability (molecular or dissociative) of H2/D2 on this surface is highly temperature-dependent, decreasing from ~0.4-0.5 below 25 K to effectively zero above 200 K. Bothmore » STM and TPD reveal that OH/OD formation is severely limited for adsorption temperatures above ~150 K. Previous literature reports of extensive surface hydroxylation from H2/D2 exposures at room temperature were most likely the result of inadvertent contamination brought about from dosing by chamber backfilling.« less

NECAP 4.1: NASA's Energy-Cost Analysis Program input manual

NASA Technical Reports Server (NTRS)

Jensen, R. N.

1982-01-01

The computer program NECAP (NASA's Energy Cost Analysis Program) is described. The program is a versatile building design and energy analysis tool which has embodied within it state of the art techniques for performing thermal load calculations and energy use predictions. With the program, comparisons of building designs and operational alternatives for new or existing buildings can be made. The major feature of the program is the response factor technique for calculating the heat transfer through the building surfaces which accounts for the building's mass. The program expands the response factor technique into a space response factor to account for internal building temperature swings; this is extremely important in determining true building loads and energy consumption when internal temperatures are allowed to swing.

Development of ultralow energy (1–10 eV) ion scattering spectrometry coupled with reflection absorption infrared spectroscopy and temperature programmed desorption for the investigation of molecular solids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bag, Soumabha; Bhuin, Radha Gobinda; Methikkalam, Rabin Rajan J.

2014-01-15

Extremely surface specific information, limited to the first atomic layer of molecular surfaces, is essential to understand the chemistry and physics in upper atmospheric and interstellar environments. Ultra low energy ion scattering in the 1–10 eV window with mass selected ions can reveal extremely surface specific information which when coupled with reflection absorption infrared (RAIR) and temperature programmed desorption (TPD) spectroscopies, diverse chemical and physical properties of molecular species at surfaces could be derived. These experiments have to be performed at cryogenic temperatures and at ultra high vacuum conditions without the possibility of collisions of neutrals and background deposition inmore » view of the poor ion intensities and consequent need for longer exposure times. Here we combine a highly optimized low energy ion optical system designed for such studies coupled with RAIR and TPD and its initial characterization. Despite the ultralow collision energies and long ion path lengths employed, the ion intensities at 1 eV have been significant to collect a scattered ion spectrum of 1000 counts/s for mass selected CH{sub 2}{sup +}.« less

On the organization and thermal behavior of functional groups on Ti3C2 MXene surfaces in vacuum

NASA Astrophysics Data System (ADS)

Persson, Ingemar; Näslund, Lars-Åke; Halim, Joseph; Barsoum, Michel W.; Darakchieva, Vanya; Palisaitis, Justinas; Rosen, Johanna; Persson, Per O. Å.

2018-03-01

The two-dimensional (2D) MXene Ti3C2T x is functionalized by surface groups (T x ) that determine its surface properties for, e.g. electrochemical applications. The coordination and thermal properties of these surface groups has, to date, not been investigated at the atomic level, despite strong variations in the MXene properties that are predicted from different coordinations and from the identity of the functional groups. To alleviate this deficiency, and to characterize the functionalized surfaces of single MXene sheets, the present investigation combines atomically resolved in situ heating in a scanning transmission electron microscope (STEM) and STEM simulations with temperature-programmed x-ray photoelectron spectroscopy (TP-XPS) in the room temperature to 750 °C range. Using these techniques, we follow the surface group coordination at the atomic level. It is concluded that the F and O atoms compete for the DFT-predicted thermodynamically preferred site and that at room temperature that site is mostly occupied by F. At higher temperatures, F desorbs and is replaced by O. Depending on the O/F ratio, the surface bare MXene is exposed as F desorbs, which enables a route for tailored surface functionalization.

Surface dynamics of micellar diblock copolymer films

NASA Astrophysics Data System (ADS)

Song, Sanghoon; Cha, Wonsuk; Kim, Hyunjung; Jiang, Zhang; Narayanan, Suresh

2011-03-01

We studied the structure and surface dynamics of poly(styrene)-b-poly(dimethylsiloxane) (PS-b-PDMS) diblock copolymer films with micellar PDMS surrounded by PS shells. By `in-situ' high resolution synchrotron x-ray reflectivity and diffuse scattering, we obtained exact thickness, electron density and surface tension. A segregation layer near the top surface was appeared with increasing temperature Surface dynamics were measured as a function of film thickness and temperature by x-ray photon correlation spectroscopy. The best fit to relaxation time constants as a function of in-plane wavevectors were analyzed with a theory based on capillary waves with hydrodynamics with bilayer model Finally the viscosities for the top segregated layer as well as for the bottom layer are obtained at given temperatures This work was supported by National Research Foundation of Korea (R15-2008-006-01001-0), Seoul Research and Business Development Program (10816), and Sogang University Research Grant (2010).

Assimilation of Goes-Derived Skin Temperature Tendencies into Mesoscale Models to Improve Forecasts of near Surface Air Temperature and Mixing Ratio

NASA Technical Reports Server (NTRS)

Lapenta, William M.; McNider, Richard T.; Suggs, Ron; Jedlovec, Gary; Robertson, Franklin R.

1998-01-01

A technique has been developed for assimilating GOES-FR skin temperature tendencies into the surface energy budget equation of a mesoscale model so that the simulated rate of temperature chance closely agrees with the satellite observations. A critical assumption of the technique is that the availability of moisture (either from the soil or vegetation) is the least known term in the model's surface energy budget. Therefore, the simulated latent heat flux, which is a function of surface moisture availability, is adjusted based upon differences between the modeled and satellite-observed skin temperature tendencies. An advantage of this technique is that satellite temperature tendencies are assimilated in an energetically consistent manner that avoids energy imbalances and surface stability problems that arise from direct assimilation of surface shelter temperatures. The fact that the rate of change of the satellite skin temperature is used rather than the absolute temperature means that sensor calibration is not as critical. An advantage of this technique for short-range forecasts (0-48 h) is that it does not require a complex land-surface formulation within the atmospheric model. As a result, the need to specify poorly known soil and vegetative characteristics is eliminated. The GOES assimilation technique has been incorporated into the PSU/NCAR MM5. Results will be presented to demonstrate the ability of the assimilation scheme to improve short- term (0-48h) simulations of near-surface air temperature and mixing ratio during the warm season for several selected cases which exhibit a variety of atmospheric and land-surface conditions. In addition, validation of terms in the simulated surface energy budget will be presented using in situ data collected at the Southern Great Plains (SGP) Cloud And Radiation Testbed (CART) site as part of the Atmospheric Radiation Measurements Program (ARM).

Effect of Temperature on the Desorption of Lithium from Molybdenum(110) Surfaces: Implications for Fusion Reactor First Wall Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Mohan; Roszell, John; Scoullos, Emanuel V.

2016-03-30

Determining the strength of Li binding to Mo is critical to assessing the survivability of Li as a potential first wall material in fusion reactors. Here, we present the results of a joint experimental and theoretical investigation into how Li desorbs from Mo(110) surfaces, based on what can be deduced from temperature-programmed desorption measurements and density functional theory (DFT). Li desorption peaks measured at temperatures ranging from 711 K (1 monolayer, ML) to 1030 K (0.04 ML), with corresponding desorption onsets from 489 to 878 K, follow a trend similar to predicted Gibbs free energies for Li adsorption. Bader chargemore » analysis of DFT densities reveals that repulsive forces between neighboring positively charged Li atoms increase with coverage and thus reduce the bond strength between Mo and Li, thereby lowering the desorption temperature as the coverage increases. In addition, DFT predicts that Li desorbs at higher temperatures from a surface with vacancies than from a perfect surface, offering an explanation for the anomalously high desorption temperatures for the last Li to desorb from Mo(110). Analysis of simulated local densities of states indicates that the stronger binding to the defective surface is correlated with enhanced interaction between Li and Mo, involving the Li 2s electrons and not only the Mo 4d electrons as in the case of the pristine surface, but also the Mo 5s electrons in the case with surface vacancies. We suggest that steps and kinks present on the Mo(110) surface behave similarly and contribute to the high desorption temperatures. These findings imply that roughened Mo surfaces may strengthen Li film adhesion at higher temperatures.« less

Chemistry of CCl 4 on Fe 3O 4(1 1 1)-(2 × 2) surfaces in the presence of adsorbed D 2O studied by temperature programmed desorption

NASA Astrophysics Data System (ADS)

Adib, K.; Totir, G. G.; Fitts, J. P.; Rim, K. T.; Mueller, T.; Flynn, G. W.; Joyce, S. A.; Osgood, R. M.

2003-07-01

Temperature programmed desorption (TPD) was used to study surface reactions of Fe 3O 4(1 1 1)-(2 × 2) sequentially exposed, at ˜100 K, to vapor-phase D 2O and CCl 4. Previous TPD and XPS results have indicated that in the absence of D 2O, CCl 4 dissociatively adsorbs on Fe 3O 4(1 1 1) producing chemisorbed Cl and CCl 2. Subsequent heating of the surface results in abstraction of lattice iron and oxygen atoms and causes them to desorb as FeCl 2 and OCCl 2, respectively. This study shows that when this Fe 3O 4 surface is exposed only to D 2O, TPD measures a rich surface chemistry with multiple desorption events extending as high as ˜800 K, indicating dissociative adsorption of D 2O on the Fe 3O 4(1 1 1) surface. After sequential exposure to D 2O and then CCl 4, the production of FeCl 2 and OCCl 2 from adsorbed CCl 4 is suppressed, indicating that D 2O fragments block the surface reactive sites.

A study of surface temperatures, clouds and net radiation

NASA Technical Reports Server (NTRS)

Dhuria, Harbans

1994-01-01

The study is continuing and it is focused on examining seasonal relationships between climate parameters such as the surface temperatures, the net radiation and cloud types and amount on a global basis for the period February 1985 to January 1987. The study consists of an analysis of the combined Earth Radiation Budget Experiment (ERBE) and International Satellite Cloud Climatology Program (ISCCP) products. The main emphasis is on obtaining the information about the interactions and relationships of Earth Radiation Budget parameters, cloud and temperature information. The purpose is to gain additional qualitative and quantitative insight into the cloud climate relationship.

Hydrogen retention in lithium and lithium oxide films

NASA Astrophysics Data System (ADS)

Buzi, L.; Yang, Y.; Domínguez-Gutiérrez, F. J.; Nelson, A. O.; Hofman, M.; Krstić, P. S.; Kaita, R.; Koel, B. E.

2018-04-01

Pure lithium (Li) surfaces are difficult to maintain in fusion devices due to rapid oxide formation, therefore, parameterizing and understanding the mechanisms of hydrogen (H, D) retention in lithium oxide (Li2O) in addition to pure Li is crucial for Li plasma-facing material applications. To compare H retention in Li and Li2O films, measurements were made as a function of surface temperature (90-520 K) under ultrahigh vacuum (UHV) conditions using temperature programmed desorption (TPD). In both cases, the total retention dropped with surface temperature, from 95% at 90 K to 35% at 520 K Li2O films retained H in similar amounts as pure Li. Molecular Dynamics (MD) modeling was used to elucidate the mechanisms of H retention, and results were consistent with experiments in terms of both retention fraction and the drop of retention with temperature.

White Dwarfs in Cataclysmic Variables: An Update

PubMed Central

Sion, Edward M.; Godon, Patrick

2018-01-01

In this review, we summarize what is currently known about the surface temperatures of accreting white dwarfs in non-magnetic and magnetic cataclysmic variables (CVs) based upon synthetic spectral analyses of far ultraviolet data. We focus only on white dwarf surface temperatures, since in the area of chemical abundances, rotation rates, WD masses and accretion rates, relatively little has changed since our last review, pending the results of a large HST GO program involving 48 CVs of different CV types. The surface temperature of the white dwarf in SS Cygni is re-examined in the light of its revised distance. We also discuss new HST spectra of the recurrent nova T Pyxidis as it transitioned into quiescence following its April 2011 nova outburst. PMID:29505036

Ground temperature measurement by PRT-5 for maps experiment

NASA Technical Reports Server (NTRS)

Gupta, S. K.; Tiwari, S. N.

1978-01-01

A simple algorithm and computer program were developed for determining the actual surface temperature from the effective brightness temperature as measured remotely by a radiation thermometer called PRT-5. This procedure allows the computation of atmospheric correction to the effective brightness temperature without performing detailed radiative transfer calculations. Model radiative transfer calculations were performed to compute atmospheric corrections for several values of the surface and atmospheric parameters individually and in combination. Polynomial regressions were performed between the magnitudes or deviations of these parameters and the corresponding computed corrections to establish simple analytical relations between them. Analytical relations were also developed to represent combined correction for simultaneous variation of parameters in terms of their individual corrections.

Comparative thermal analysis of the Space Station Freedom photovoltaic deployable boom structure using TRASYS, NEVADA, and SINDA programs

NASA Technical Reports Server (NTRS)

Baumeister, Joseph F.; Beach, Duane E.; Armand, Sasan C.

1989-01-01

The proposed Space Station Photovoltaic Deployable Boom was analyzed for operating temperatures. The boom glass/epoxy structure design needs protective shielding from environmental degradation. The protective shielding optical properties (solar absorptivity and emissivity) dictate the operating temperatures of the boom components. The Space Station Boom protective shielding must also withstand the effects of the extendible/retractable coiling acting within the mast canister. A thermal analysis method was developed for the Space Station Deployable Boom to predict transient temperatures for a variety of surface properties. The modeling procedures used to evaluate temperatures within the boom structure incorporated the TRASYS, NEVADA, and SINDA thermal analysis programs. Use of these programs led to a comparison between TRASYS and NEVADA analysis methods. Comparing TRASYS and NEVADA results exposed differences in the environmental solar flux predictions.

Comparative thermal analysis of the space station Freedom photovoltaic deployable boom structure using TRASYS, NEVADA, and SINDA programs

NASA Technical Reports Server (NTRS)

Baumeister, Joseph F.; Beach, Duane E.; Armand, Sasan C.

1989-01-01

The proposed Space Station Photovoltaic Deployable Boom was analyzed for operating temperatures. The boom glass/epoxy structure design needs protective shielding from environmental degradation. The protective shielding optical properties (solar absorptivity and emissivity) dictate the operating temperatures of the boom components. The Space Station Boom protective shielding must also withstand the effects of the extendible/retractable coiling action within the mast canister. A thermal analysis method was developed for the Space Station Deployable Boom to predict transient temperatures for a variety of surface properties. The modeling procedures used to evaluate temperatures within the boom structure incorporated the TRASYS, NEVADA, and SINDA thermal analysis programs. Use of these programs led to a comparison between TRASYS and NEVADA analysis methods. Comparing TRASYS and NEVADA results exposed differences in the environmental solar flux predictions.

Methanol Oxidation Using Ozone on Titania-Supported Vanadium Catalyst

EPA Science Inventory

Ozone-enhanced catalytic oxidation of methanol has been conducted at mild temperatures of 100 to 250NC using V2O5/TiO2 catalyst prepared by the sol-gel method. The catalyst was characterized using XRD, surface area measurements, and temperature-programmed desorption of methanol. ...

Performance of Surface-Mount Ceramic and Solid Tantalum Capacitors for Cryogenic Applications

NASA Technical Reports Server (NTRS)

Patterson, Richard L.; MacDonald, Thomas L.; Hammoud, Ahmad; Gerber, Scott

1998-01-01

Low temperature electronics are of great interest for space exploration programs. These include missions to the outer planets, earth-orbiting and deep-space probes, remote-sensing and communication satellites. Terrestrial applications would also benefit from the availability of low temperature electronics. Power components capable of low temperature operation would, thus, enhance the technologies needed for the development of advanced power systems suitable for use in harsh environments. In this work, ceramic and solid tantalum capacitors were evaluated in terms of their dielectric properties as a function of temperature and at various frequencies. The surface-mount devices were characterized in terms of their capacitance stability and dissipation factor in the frequency range of 50 Hz to 100 kHz at temperatures ranging from room temperature (20 deg. C) to about liquid nitrogen temperature (-190 deg. C). The results are discussed and conclusions made concerning the suitability of the capacitors investigated for low temperature applications.

Temperature distributions and thermal stresses in a graded zirconia/metal gas path seal system for aircraft gas turbine engines

NASA Technical Reports Server (NTRS)

Taylor, C. M.; Bill, R. C.

1978-01-01

A ceramic/metallic aircraft gas turbine outer gas path seal designed for improved engine performance was studied. Transient temperature and stress profiles in a test seal geometry were determined by numerical analysis. During a simulated engine deceleration cycle from sea-level takeoff to idle conditions, the maximum seal temperature occurred below the seal surface, therefore the top layer of the seal was probably subjected to tensile stresses exceeding the modulus of rupture. In the stress analysis both two- and three-dimensional finite element computer programs were used. Predicted trends of the simpler and more easily usable two-dimensional element programs were borne out by the three-dimensional finite element program results.

Columbia: The first five flights entry heating data series. Volume 2: The OMS Pod

NASA Technical Reports Server (NTRS)

Williams, S. D.

1983-01-01

Entry heating flight data and wind tunnel data on the OMS Pod are presented for the first five flights of the Space Shuttle Orbiter. The heating rate data are presented in terms of normalized film heat transfer coefficients as a function of angle-of-attack, Mach number, and normal shock Reynolds number. The surface heating rates and temperatures were obtained via the JSC NONLIN/INVERSE computer program. Time history plots of the surface heating rates and temperatures are also presented.

Pathways for Ethanol Dehydrogenation and Dehydration Catalyzed by Ceria (111) and (100) Surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beste, Ariana; Steven Overbury

2015-01-08

We have performed computations to better understand how surface structure affects selectivity in dehydrogenation and dehydration reactions of alcohols. Ethanol reactions on the (111) and (100) ceria surfaces were studied starting from the dominant surface species, ethoxy. We used DFT (PBE+U) to explore reaction pathways leading to ethylene and acetaldehyde and calculated estimates of rate constants employing transition state theory. To assess pathway contributions, we carried out kinetic analysis. Our results show that intermediate and transition state structures are stabilized on the (100) surface compared to the (111) surface. Formation of acetaldehyde over ethylene is kinetically and thermodynamically preferred onmore » both surfaces. Our results are consistent with temperature programmed surface reaction and steady-state experiments, where acetaldehyde was found as the main product and evidence was presented that ethylene formation at higher temperature originates from changes in adsorbate and surface structure.« less

Experimental and theoretical study of shuttle lee-side heat transfer rates

NASA Technical Reports Server (NTRS)

Mruk, G. K.; Bertin, J.; Lamb, J. P.

1975-01-01

The experimental program which was conducted in the Calspan 96-inch hypersonic shock tunnel to investigate what effect the windward surface temperature had on the heat transfer to the leeward surface of the space shuttle orbiter is discussed. Heat-transfer distributions, surface-pressure distributions, and schlieren photographs were obtained for an 0.01-scale model of the 139 configuration space shuttle orbiter at angles-of-attack of 30 and 40 deg. Similar data were obtained for an 0.01 scale wingless model of the 139 configuration at angles-of-attack of 30 and 90 deg. Data were obtained for Mach numbers from Reynolds numbers, and surface temperatures and compared with theoretical results.

Multidimensional effects in the thermal response of fuel rod simulators. [PWR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dabbs, R.D.; Ott, L.J.

1980-01-01

One of the primary objectives of the Oak Ridge National Laboratory Pressurized-Water Reactor Blowdown Heat Transfer Separate-Effects Program is the determination of the transient surface temperature and surface heat flux of fuel pin simulators (FPSs) from internal thermocouple signals obtained during a loss-of-coolant experiment (LOCE) in the Thermal-Hydraulics Test Facility. This analysis requires the solution of the classical inverse heat conduction problem. The assumptions that allow the governing differential equation to be reduced to one dimension can introduce significant errors in the computed surface heat flux and surface temperature. The degree to which these computed variables are perturbed is addressedmore » and quantified.« less

Automated calculation of surface energy fluxes with high-frequency lake buoy data

USGS Publications Warehouse

Woolway, R. Iestyn; Jones, Ian D; Hamilton, David P.; Maberly, Stephen C; Muroaka, Kohji; Read, Jordan S.; Smyth, Robyn L; Winslow, Luke A.

2015-01-01

Lake Heat Flux Analyzer is a program used for calculating the surface energy fluxes in lakes according to established literature methodologies. The program was developed in MATLAB for the rapid analysis of high-frequency data from instrumented lake buoys in support of the emerging field of aquatic sensor network science. To calculate the surface energy fluxes, the program requires a number of input variables, such as air and water temperature, relative humidity, wind speed, and short-wave radiation. Available outputs for Lake Heat Flux Analyzer include the surface fluxes of momentum, sensible heat and latent heat and their corresponding transfer coefficients, incoming and outgoing long-wave radiation. Lake Heat Flux Analyzer is open source and can be used to process data from multiple lakes rapidly. It provides a means of calculating the surface fluxes using a consistent method, thereby facilitating global comparisons of high-frequency data from lake buoys.

MR thermometry analysis program for laser- or high-intensity focused ultrasound (HIFU)-induced heating at a clinical MR scanner

NASA Astrophysics Data System (ADS)

Kim, Eun Ju; Jeong, Kiyoung; Oh, Seung Jae; Kim, Daehong; Park, Eun Hae; Lee, Young Han; Suh, Jin-Suck

2014-12-01

Magnetic resonance (MR) thermometry is a noninvasive method for monitoring local temperature change during thermal therapy. In this study, a MR temperature analysis program was established for a laser with gold nanorods (GNRs) and high-intensity focused ultrasound (HIFU)-induced heating MR thermometry. The MR temperature map was reconstructed using the water proton resonance frequency (PRF) method. The temperature-sensitive phase difference was acquired by using complex number subtraction instead of direct phase subtraction in order to avoid another phase unwrapping process. A temperature map-analyzing program was developed and implemented in IDL (Interactive Data Language) for effective temperature monitoring. This one program was applied to two different heating devices at a clinical MR scanner. All images were acquired with the fast spoiled gradient echo (fSPGR) pulse sequence on a 3.0 T GE Discovery MR750 scanner with an 8-channel knee array coil or with a home-built small surface coil. The analyzed temperature values were confirmed by using values simultaneously measured with an optical temperature probe (R2 = 0.996). The temperature change in small samples induced by a laser or by HIFU was analyzed by using a raw data, that consisted of complex numbers. This study shows that our MR thermometry analysis program can be used for thermal therapy study with a laser or HIFU at a clinical MR scanner. It can also be applied to temperature monitoring for any other thermal therapy based on the PRF method.

Hydrogen retention in lithium and lithium oxide films

DOE PAGES

Buzi, L.; Yang, Y.; Dominguez-Gutierrez, F. J.; ...

2018-02-09

Pure lithium (Li) surfaces are difficult to maintain in fusion devices due to rapid oxide formation, therefore, parameterizing and understanding the mechanisms of hydrogen (H, D) retention in lithium oxide (Li 2O) in addition to pure Li is crucial for Li plasma-facing material applications. To compare H retention in Li and Li 2O films, measurements were made as a function of surface temperature (90–520 K) under ultrahigh vacuum (UHV) conditions using temperature programmed desorption (TPD). In both cases, the total retention dropped with surface temperature, from 95% at 90 K to 35% at 520 K Li 2O films retained Hmore » in similar amounts as pure Li. Finally, Molecular Dynamics (MD) modeling was used to elucidate the mechanisms of H retention, and results were consistent with experiments in terms of both retention fraction and the drop of retention with temperature.« less

Hydrogen retention in lithium and lithium oxide films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buzi, L.; Yang, Y.; Dominguez-Gutierrez, F. J.

Pure lithium (Li) surfaces are difficult to maintain in fusion devices due to rapid oxide formation, therefore, parameterizing and understanding the mechanisms of hydrogen (H, D) retention in lithium oxide (Li 2O) in addition to pure Li is crucial for Li plasma-facing material applications. To compare H retention in Li and Li 2O films, measurements were made as a function of surface temperature (90–520 K) under ultrahigh vacuum (UHV) conditions using temperature programmed desorption (TPD). In both cases, the total retention dropped with surface temperature, from 95% at 90 K to 35% at 520 K Li 2O films retained Hmore » in similar amounts as pure Li. Finally, Molecular Dynamics (MD) modeling was used to elucidate the mechanisms of H retention, and results were consistent with experiments in terms of both retention fraction and the drop of retention with temperature.« less

Menu driven heat treatment control of thin walled bodies

DOEpatents

Kothmann, Richard E.; Booth, Jr., Russell R.; Grimm, Noel P.; Batenburg, Abram; Thomas, Vaughn M.

1992-01-01

A process for controlling the heating of a thin-walled body according to a predetermined temperature program by means of electrically controllable heaters, comprising: disposing the heaters adjacent one surface of the body such that each heater is in facing relation with a respective zone of the surface; supplying heat-generating power to each heater and monitoring the temperature at each surface zone; and for each zone: deriving (16,18,20), on the basis of the temperature values obtained in the monitoring step, estimated temperature values of the surface at successive time intervals each having a first selected duration; generating (28), on the basis of the estimated temperature values derived in each time interval, representations of the temperature, THSIFUT, which each surface zone will have, based on the level of power presently supplied to each heater, at a future time which is separated from the present time interval by a second selected duration; determining (30) the difference between THSIFUT and the desired temperature, FUTREFTVZL, at the future time which is separated from the present time interval by the second selected duration; providing (52) a representation indicating the power level which sould be supplied to each heater in order to reduce the difference obtained in the determining step; and adjusting the power level supplied to each heater by the supplying step in response to the value of the representation provided in the providing step.

Structural-Thermal-Optical Program (STOP)

NASA Technical Reports Server (NTRS)

Lee, H. P.

1972-01-01

A structural thermal optical computer program is developed which uses a finite element approach and applies the Ritz method for solving heat transfer problems. Temperatures are represented at the vertices of each element and the displacements which yield deformations at any point of the heated surface are interpolated through grid points.

Calculation methods for steadily loaded, off-set pivot, tilting pad thrust bearings. (Guide to use of computer program A9235.)

NASA Astrophysics Data System (ADS)

1992-12-01

ESDU 92035 provides details of a FORTRAN program that implements the calculation method of ESDU 83004. It allows performance analysis of an existing design, or the design of a bearing dimensions, subject to any space constraint, are recommended. The predicted performance includes the lubricant film thickness under load, its temperature and flow rate, the power loss, and the bearing temperature. Recommendations are also made on surface finish. Warning messages are output in the following cases, for each of which possible remedial actions are suggested: drain or pad temperature too high, churning losses too great, film thickness too small, pad number too high, ratio or inner to outer pad radius too large, flow rate too great, lubricant or pad temperature outside usable range. A lubricant database is provided that may be extended or edited. The program applies to Newtonian lubricants in laminar flow. Worked examples illustrate the use of the program.

Atmospheric radiation measurement program facilities newsletter, September 2001.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holdridge, D. J.

Our Changing Climate--Is our climate really changing? How do we measure climate change? How can we predict what Earth's climate will be like for generations to come? One focus of the Atmospheric Radiation Measurement (ARM) Program is to improve scientific climate models enough to achieve reliable regional prediction of future climate. According to the Environmental Protection Agency (EPA), the global mean surface temperature has increased by 0.5-1.0 F since the late 19th century. The 20th century's 10 warmest years all occurred in the last 15 years of the century, with 1998 being the warmest year of record. The global meanmore » surface temperature is measured by a network of temperature-sensing instruments distributed around the world, including ships, ocean buoys, and weather stations on land. The data from this network are retrieved and analyzed by various organizations, including the National Aeronautics and Space Administration, the National Oceanic and Atmospheric Administration, and the World Meteorological Organization. Worldwide temperature records date back to 1860. To reconstruct Earth's temperature history before 1860, scientists use limited temperature records, along with proxy indicators such as tree rings, pollen records, and analysis of air frozen in ancient ice. The solar energy received from the sun drives Earth's weather and climate. Some of this energy is reflected and filtered by the atmosphere, but most is absorbed by Earth's surface. The absorbed solar radiation warms the surface and is re-radiated as heat energy into the atmosphere. Some atmospheric gases, called greenhouse gases, trap some of the re-emitted heat, keeping the surface temperature regulated and suitable for sustaining life. Although the greenhouse effect is natural, some evidence indicates that human activities are producing increased levels of some greenhouse gases such as carbon dioxide, methane, and nitrous oxide. Scientists believe that the combustion of fossil fuels is responsible for the increased levels of carbon dioxide in the atmosphere. According to the EPA, the burning of fossil fuels for cars and trucks, the heating of homes and businesses, and the operation of power plants account for approximately 98% of U.S. carbon dioxide emissions. The increase of greenhouse gases will, theoretically, enhance the greenhouse effect by trapping more of the heat energy emitted by Earth's surface, thus increasing the surface temperatures on a global scale. Scientists expect that the global average surface temperature could rise 1-4.5 F in the next 50 years and as much as 10 F in the next century. Global warming could potentially have harmful effects on human health, water resources, forests, agriculture, wildlife, and coastal areas. A few degrees of warming might lead to more frequent and severe heat waves, worsened air pollution with adverse effects on human respiratory health, and wider spread of tropical disease such as malaria. The world's hydrologic cycle might be affected by an increase in evaporation and, thus, in precipitation. An increase in evaporation will increase atmospheric water vapor, a significant natural greenhouse gas. The increase in water vapor might further enhance the global warming caused by the greenhouse effect. This is known as a positive feedback. The increase in water vapor could also change the amount of clouds present in the atmosphere, which could reduce temperatures in a negative feedback. Many interrelated factors affect the global climate and are responsible for climate change. Predicting the outcome of the interactions among the many factors is not easy, but it must be addressed. The ARM Program is taking a lead in this effort by collecting vast amounts of data whose analysis will improve our forecasting models for both daily weather and long-term climate. For more information on the ARM Program, please visit our web site at www.arm.gov.« less

Heat Transfer Measurements during DC Casting of Aluminium Part I: Measurement Technique

NASA Astrophysics Data System (ADS)

Bakken, J. A.; Bergström, T.

A method for determination of surface heat transfer to the cooling water and mould based on in-situ temperature measurements in the DC cast ingot has been developed. Three or more steel mantled coaxial thermocouples (0.5 mm diam.) are mounted on a wire frame called a "harp". Allowing the "harp" to freeze into the solid ingots during the casting time-temperature plots T1 (t), T2(t), T3 (t) are obtained for three moving points positioned typically 3, 7 and 11 mm from the ingot surface. From these measurements surface temperature, heat flux and heat transfer coefficients are computed as functions of vertical distance. The computer program is based on steady-state two-dimensional heat balances with convective terms for two fixed volume elements: one around thermocouple T1 and one surface element. A special numerical smoothing procedure is incorporated. The heat of solidification is taken into account.

Calculation of the Naval Long and Short Waste Package Three-Dimensional Thermal Interface Temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

H. Marr

2006-10-25

The purpose of this calculation is to evaluate the thermal performance of the Naval Long and Naval Short spent nuclear fuel (SNF) waste packages (WP) in the repository emplacement drift. The scope of this calculation is limited to the determination of the temperature profiles upon the surfaces of the Naval Long and Short SNF waste package for up to 10,000 years of emplacement. The temperatures on the top of the outside surface of the naval canister are the thermal interfaces for the Naval Nuclear Propulsion Program (NNPP). The results of this calculation are intended to support Licensing Application design activities.

Manufacture of Cryoshroud Surfaces for Space Simulation Chambers

NASA Technical Reports Server (NTRS)

Ash, Gary S.

2008-01-01

Environmental test chambers for space applications use internal shrouds to simulate temperature conditions encountered in space. Shroud temperatures may range from +150 C to -253 C (20 K), and internal surfaces are coated with special high emissivity/absorptivity paints. To obtain temperature uniformity over large areas, detailed thermal design is required for placement of tubing for gaseous or liquid nitrogen and helium and other exotic heat exchange fluids. The recent increase in space simulation activity related to the James Webb Space Telescope has led to the design of new cryogenic shrouds to meet critical needs in instrument package testing. This paper will review the design and manufacturing of shroud surfaces for several of these programs, including fabrication methods and the selection and application of paints for simulation chambers.

Novel Phenylethynyl Imide Silanes as Coupling Agents for Titanium Alloy

NASA Technical Reports Server (NTRS)

Park, C.; Lowther, S. E.; Smith, J. G., Jr.; Conell, J. W.; Hergenrother, P. M.; SaintClair, T. L.

2004-01-01

The durability of titanium (Ti) alloys bonded with high temperature adhesives such as polyimides has failed to attain the level of performance required for many applications. The problem to a large part is attributed to the instability of the surface treatment on the Ti substrate. Although Ti alloy adhesive specimens with surface treatments such as chromic acid anodization, Pasa-Jell, Turco, etc. have provided high initial mechanical properties, these properties have decreased as a function of aging at ambient temperature and faster, when aged at elevated temperatures or in a hot-wet environment. As part of the High Speed Civil Transport program where Ti honeycomb sandwich structure must perform for 60,000 hours at 177 C, work was directed to the development of environmentally safe, durable Ti alloy surface treatments.

Spatial-temporal analysis of building surface temperatures in Hung Hom

NASA Astrophysics Data System (ADS)

Zeng, Ying; Shen, Yueqian

2015-12-01

This thesis presents a study on spatial-temporal analysis of building surface temperatures in Hung Hom. Observations were collected from Aug 2013 to Oct 2013 at a 30-min interval, using iButton sensors (N=20) covering twelve locations in Hung Hom. And thermal images were captured in PolyU from 05 Aug 2013 to 06 Aug 2013. A linear regression model of iButton and thermal records is established to calibrate temperature data. A 3D modeling system is developed based on Visual Studio 2010 development platform, using ArcEngine10.0 component, Microsoft Access 2010 database and C# programming language. The system realizes processing data, spatial analysis, compound query and 3D face temperature rendering and so on. After statistical analyses, building face azimuths are found to have a statistically significant relationship with sun azimuths at peak time. And seasonal building temperature changing also corresponds to the sun angle and sun azimuth variations. Building materials are found to have a significant effect on building surface temperatures. Buildings with lower albedo materials tend to have higher temperatures and larger thermal conductivity material have significant diurnal variations. For the geographical locations, the peripheral faces of campus have higher temperatures than the inner faces during day time and buildings located at the southeast are cooler than the western. Furthermore, human activity is found to have a strong relationship with building surface temperatures through weekday and weekend comparison.

High Speed Surface Thermocouples Interface to Wireless Transmitters

DTIC Science & Technology

2017-03-15

Government and/or Private Sector Use Being able to measure high-speed surface temperatures in hostile environments where wireless transmission of the data...09/16/2016 See Item 16 Draft Reg Repro 16. REMARKS Eric Gingrich, COR I Item 0: High Speed Surface Thermocouples Interface to Wireless ...Speed Surface Thermocouples Interface to Wireless Transmitters W56HZV-16-C-0149 Sb. GRANT NUMBER Sc. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Sd. PROJECT

An investigation of satellite sounding products for the remote sensing of the surface energy balance and soil moisture

NASA Technical Reports Server (NTRS)

Diak, George R.

1989-01-01

Improved techniques for the remote sensing of the land surface energy balance (SEB) and soil moisture would greatly improve prediction of climate and weather as well as be of benefit to agriculture, hydrology and many associated fields. Most of the satellite remote sensing methods which were researched to date rely upon satellite-measured infrared surface temperatures or their time changes as a remote sensing signal. Optimistically, only four or five levels of information (wet to dry) in surface heating/evaporation are discernable by surface temperature methods and a good understanding of atmospheric conditions is necessary to bring them to this accuracy level. Skin temperature methods were researched as well as begun work on several new methods for the remote sensing of the SEB, some elements of which are applicable to current and retrospective data sources and some which will rely on instrumentation from the Earth Observing System (EOS) program in the 1990s.

Surface atmospheric extremes (launch and transportation areas)

NASA Technical Reports Server (NTRS)

1974-01-01

Criteria are provided on atmospheric extremes from the surface to 150 meters for geographical locations of interest to NASA. Thermal parameters (temperature and solar radiation), humidity, precipitation, pressure, and atmospheric electricity (lightning and static) are presented. Available data are also provided for the entire continental United States for use in future space programs.

Pattern Analysis of El Nino and La Nina Phenomenon Based on Sea Surface Temperature (SST) and Rainfall Intensity using Oceanic Nino Index (ONI) in West Java Area

NASA Astrophysics Data System (ADS)

Prasetyo, Yudo; Nabilah, Farras

2017-12-01

Climate change occurs in 1998-2016 brings significant alteration in the earth surface. It is affects an extremely anomaly temperature such as El Nino and La Nina or mostly known as ENSO (El Nino Southern Oscillation). West Java is one of the regions in Indonesia that encounters the impact of this phenomenon. Climate change due to ENSO also affects food production and other commodities. In this research, processing data method is conducted using programming language to process SST data and rainfall data from 1998 to 2016. The data are sea surface temperature from NOAA satellite, SST Reynolds (Sea Surface Temperature) and daily rainfall temperature from TRMM satellite. Data examination is done using analysis of rainfall spatial pattern and sea surface temperature (SST) where is affected by El Nino and La Nina phenomenon. This research results distribution map of SST and rainfall for each season to find out the impacts of El Nino and La Nina around West Java. El Nino and La Nina in Java Sea are occurring every August to February. During El Nino, sea surface temperature is between 27°C - 28°C with average temperature on 27.71°C. Rainfall intensity is 1.0 mm/day - 2.0 mm/day and the average are 1.63 mm/day. During La Nina, sea surface temperature is between 29°C - 30°C with average temperature on 29.06°C. Rainfall intensity is 9.0 mm/day - 10 mm/day, and the average is 9.74 mm/day. The correlation between rainfall and SST is 0,413 which is expresses a fairly strong correlation between parameters. The conclusion is, during La Nina SST and rainfall increase. While during El Nino SST and rainfall decrease. Hopefully this research could be a guideline to plan disaster mitigation in West Java region that is related extreme climate change.

1DTempPro: analyzing temperature profiles for groundwater/surface-water exchange

USGS Publications Warehouse

Voytek, Emily B.; Drenkelfuss, Anja; Day-Lewis, Frederick D.; Healy, Richard; Lane, John W.; Werkema, Dale D.

2014-01-01

A new computer program, 1DTempPro, is presented for the analysis of vertical one-dimensional (1D) temperature profiles under saturated flow conditions. 1DTempPro is a graphical user interface to the U.S. Geological Survey code Variably Saturated 2-Dimensional Heat Transport (VS2DH), which numerically solves the flow and heat-transport equations. Pre- and postprocessor features allow the user to calibrate VS2DH models to estimate vertical groundwater/surface-water exchange and also hydraulic conductivity for cases where hydraulic head is known.

Radiometer Calibrations: Saving Time by Automating the Gathering and Analysis Procedures

NASA Technical Reports Server (NTRS)

Sadino, Jeffrey L.

2005-01-01

Mr. Abtahi custom-designs radiometers for Mr. Hook's research group. Inherently, when the radiometers report the temperature of arbitrary surfaces, the results are affected by errors in accuracy. This problem can be reduced if the errors can be accounted for in a polynomial. This is achieved by pointing the radiometer at a constant-temperature surface. We have been using a Hartford Scientific WaterBath. The measurements from the radiometer are collected at many different temperatures and compared to the measurements made by a Hartford Chubb thermometer with a four-decimal point resolution. The data is analyzed and fit to a fifth-order polynomial. This formula is then uploaded into the radiometer software, enabling accurate data gathering. Traditionally, Mr. Abtahi has done this by hand, spending several hours of his time setting the temperature, waiting for stabilization, taking measurements, and then repeating for other temperatures. My program, written in the Python language, has enabled the data gathering and analysis process to be handed off to a less-senior member of the team. Simply by entering several initial settings, the program will simultaneously control all three instruments and organize the data suitable for computer analyses, thus giving the desired fifth-order polynomial. This will save time, allow for a more complete calibration data set, and allow for base calibrations to be developed. The program is expandable to simultaneously take any type of measurement from up to nine distinct instruments.

Finding Blackbody Temperature and Emissivity on a Sub-Pixel Scale

NASA Astrophysics Data System (ADS)

Bernstein, D. J.; Bausell, J.; Grigsby, S.; Kudela, R. M.

2015-12-01

Surface temperature and emissivity provide important insight into the ecosystem being remotely sensed. Dozier (1981) proposed a an algorithm to solve for percent coverage and temperatures of two different surface types (e.g. sea surface, cloud cover, etc.) within a given pixel, with a constant value for emissivity assumed. Here we build on Dozier (1981) by proposing an algorithm that solves for both temperature and emissivity of a water body within a satellite pixel by assuming known percent coverage of surface types within the pixel. Our algorithm generates thermal infrared (TIR) and emissivity end-member spectra for the two surface types. Our algorithm then superposes these end-member spectra on emissivity and TIR spectra emitted from four pixels with varying percent coverage of different surface types. The algorithm was tested preliminarily (48 iterations) using simulated pixels containing more than one surface type, with temperature and emissivity percent errors of ranging from 0 to 1.071% and 2.516 to 15.311% respectively[1]. We then tested the algorithm using a MASTER image from MASTER collected as part of the NASA Student Airborne Research Program (NASA SARP). Here the temperature of water was calculated to be within 0.22 K of in situ data. The algorithm calculated emissivity of water with an accuracy of 0.13 to 1.53% error for Salton Sea pixels collected with MASTER, also collected as part of NASA SARP. This method could improve retrievals for the HyspIRI sensor. [1] Percent error for emissivity was generated by averaging percent error across all selected bands widths.

Deuterium sputtering of Li and Li-O films

NASA Astrophysics Data System (ADS)

Nelson, Andrew; Buzi, Luxherta; Kaita, Robert; Koel, Bruce

2017-10-01

Lithium wall coatings have been shown to enhance the operational plasma performance of many fusion devices, including NSTX and other tokamaks, by reducing the global wall recycling coefficient. However, pure lithium surfaces are extremely difficult to maintain in experimental fusion devices due to both inevitable oxidation and codeposition from sputtering of hot plasma facing components. Sputtering of thin lithium and lithium oxide films on a molybdenum target by energetic deuterium ion bombardment was studied in laboratory experiments conducted in a surface science apparatus. A Colutron ion source was used to produce a monoenergetic, mass-selected ion beam. Measurements were made under ultrahigh vacuum conditions as a function of surface temperature (90-520 K) using x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and temperature programmed desorption (TPD). Results are compared with computer simulations conducted on a temperature-dependent data-calibrated (TRIM) model.

Investigation of the reaction of 5Al-2.5Sn titanium with hydrogen at subzero temperature

NASA Technical Reports Server (NTRS)

Williams, D. N.; Wood, R. A.

1972-01-01

An investigation of the effect of temperature on the surface hydriding reaction of 5Al-2.5Sn titanium exposed to hydrogen at 250 psig was made. The temperature range studied extended from 160 F to -160 F. Reaction conditions were controlled so as to expose a vacuum-cleaned, oxide-free alloy surface to an ultrapure hydrogen atmosphere. Reaction times up to 1458 hours were studied. The hydriding reaction was extremely sensitive to experimental variables and the reproducibility of reaction behavior was poor. However, it was demonstrated that the reaction proceeded quite rapidly at 160 F; as much as 1 mil surface hydriding being observed after exposure for 162 hours. The amount of hydriding appeared to decrease with decreasing temperature at 75 F, -36 F, and -76 F. No surface hydriding was detected either by vacuum fusion analysis or by metallographic examination after exposure for 1458 hours at -110 F or -160 F. Tensile properties were unaffected by surface hydriding of the severity developed in this program (up to 1 mil thick) as determined by slow strain rate testing of hydrided sheet tensile samples.

Programmable thermal emissivity structures based on bioinspired self-shape materials

NASA Astrophysics Data System (ADS)

Athanasopoulos, N.; Siakavellas, N. J.

2015-12-01

Programmable thermal emissivity structures based on the bioinspired self-shape anisotropic materials were developed at macro-scale, and further studied theoretically at smaller scale. We study a novel concept, incorporating materials that are capable of transforming their shape via microstructural rearrangements under temperature stimuli, while avoiding the use of exotic shape memory materials or complex micro-mechanisms. Thus, programmed thermal emissivity behaviour of a surface is achievable. The self-shape structure reacts according to the temperature of the surrounding environment or the radiative heat flux. A surface which incorporates self-shape structures can be designed to quickly absorb radiative heat energy at low temperature levels, but is simultaneously capable of passively controlling its maximum temperature in order to prevent overheating. It resembles a “game” of colours, where two or more materials coexist with different values of thermal emissivity/ absorptivity/ reflectivity. The transformation of the structure conceals or reveals one of the materials, creating a surface with programmable - and therefore, variable- effective thermal emissivity. Variable thermal emissivity surfaces may be developed with a total hemispherical emissivity ratio (ɛEff_H/ɛEff_L) equal to 28.

Programmable thermal emissivity structures based on bioinspired self-shape materials

PubMed Central

Athanasopoulos, N.; Siakavellas, N. J.

2015-01-01

Programmable thermal emissivity structures based on the bioinspired self-shape anisotropic materials were developed at macro-scale, and further studied theoretically at smaller scale. We study a novel concept, incorporating materials that are capable of transforming their shape via microstructural rearrangements under temperature stimuli, while avoiding the use of exotic shape memory materials or complex micro-mechanisms. Thus, programmed thermal emissivity behaviour of a surface is achievable. The self-shape structure reacts according to the temperature of the surrounding environment or the radiative heat flux. A surface which incorporates self-shape structures can be designed to quickly absorb radiative heat energy at low temperature levels, but is simultaneously capable of passively controlling its maximum temperature in order to prevent overheating. It resembles a “game” of colours, where two or more materials coexist with different values of thermal emissivity/ absorptivity/ reflectivity. The transformation of the structure conceals or reveals one of the materials, creating a surface with programmable – and therefore, variable- effective thermal emissivity. Variable thermal emissivity surfaces may be developed with a total hemispherical emissivity ratio (εEff_H/εEff_L) equal to 28. PMID:26635316

Global mean sea level - Indicator of climate change

NASA Technical Reports Server (NTRS)

Robock, A.; Hansen, J.; Gornitz, V.; Lebedeff, S.; Moore, E.; Etkins, R.; Epstein, E.

1983-01-01

A critical discussion is presented on the use by Etkins and Epstein (1982) of combined surface air temperature and sea level time series to draw conclusions concerning the discharge of the polar ice sheets. It is objected by Robock that they used Northern Hemisphere land surface air temperature records which are unrepresentative of global sea surface temperature, and he suggests that externally imposed volcanic dust and CO2 forcings can adequately account for observed temperature changes over the last century, with global sea level changing in passive response to sea change as a result of thermal expansion. Hansen et al. adduce evidence for global cooling due to ice discharge that has not exceeded a few hundredths of a degree centigrade in the last century, precluding any importance of this phenomenon in the interpretation of global mean temperature trends for this period. Etkins and Epstein reply that since their 1982 report additional evidence has emerged for the hypothesis that the polar ice caps are diminishing. It is reasserted that each of the indices discussed, including global mean sea surface temperature and sea level, polar ice sheet mass balance, water mass characteristics, and the spin rate and axis of rotation displacement of the earth, are physically linked and can be systematically monitored, as is currently being planned under the auspices of the National Climate Program.

Drastic reduction of adsorption of CO and H2 on (111)-type Pd layers

NASA Technical Reports Server (NTRS)

Poppa, H.; Soria, F.

1983-01-01

Clean surfaces of (111)-type Pd layers, grown from the vapor phase on Mo(110) at room temperature, were used to study the adsorption of CO and H2 by temperature-programmed desorption, Auger electron spectroscopy, and low-energy electron diffraction. Mild annealing of the as-grown layers during a single desorption cycle (to about 600 K) drastically reduces the adsorption for both adsorbates. Low-dose argon-ion bombardment introduces surface imperfections which restore a high adsorption probability. The results are interpreted in terms of particular (111)-type surface structures that persist tp layer thicknesses of about four monolayers; the results raise questions with respect to the surface structure of supported thin epitaxial islands and particles of Pd and possibly also with respect to conventional methods of preparing bulk surfaces of Pd for adsorption studies.

Measurements of Polyatomic Molecule Formation on an Icy Grain Analog Using Fast Atoms

NASA Technical Reports Server (NTRS)

Chutjian, A.; Madsunkov, S.; Shortt, B. J.; MacAskill, J. A.; Darrach, M. R.

2006-01-01

Carbon dioxide has been produced from the impact of a monoenergetic O(P-3) beam upon a surface cooled to 4.8 K and covered with a CO ice. Using temperature-programmed desorption and mass spectrometer detection, we have detected increasing amounts of CO2 formation with O(P-3) energies of 2, 5, 10, and 14 eV. This is the first measurement of polyatomic molecule formation on a surface with superthermal atoms. The goal of this work is to detect other polyatomic species, such as CH3OH, which can be formed under conditions that simulate the grain temperature, surface coverage, and superthermal atoms present in shock-heated circumstellar and interstellar regions.

Proof test criteria for thin-walled 2219 aluminum pressure vessels. Volume 1: Program summary and data analysis

NASA Technical Reports Server (NTRS)

Finger, R. W.

1976-01-01

This experimental program was undertaken to investigate the crack growth behavior of deep surface flaws in 2219 aluminum. The program included tests of uniaxially loaded surface flaw and center crack panels at temperatures ranging from 20K (-423 F) to ambient. The tests were conducted on both the base metal and as-welded weld metal material. The program was designed to provide data on the mechanisms of failure by ligament penetration, and the residual cyclic life, after proof-testing, of a vessel which has been subjected to incipient penetration by the proof test. The results were compared and analyzed with previously developed data to develop guidelines for the proof testing of thin walled 2219 pressure vessels.

Atmospheric Downscaling using Genetic Programming

NASA Astrophysics Data System (ADS)

Zerenner, Tanja; Venema, Victor; Simmer, Clemens

2013-04-01

Coupling models for the different components of the Soil-Vegetation-Atmosphere-System requires up-and downscaling procedures. Subject of our work is the downscaling scheme used to derive high resolution forcing data for land-surface and subsurface models from coarser atmospheric model output. The current downscaling scheme [Schomburg et. al. 2010, 2012] combines a bi-quadratic spline interpolation, deterministic rules and autoregressive noise. For the development of the scheme, training and validation data sets have been created by carrying out high-resolution runs of the atmospheric model. The deterministic rules in this scheme are partly based on known physical relations and partly determined by an automated search for linear relationships between the high resolution fields of the atmospheric model output and high resolution data on surface characteristics. Up to now deterministic rules are available for downscaling surface pressure and partially, depending on the prevailing weather conditions, for near surface temperature and radiation. Aim of our work is to improve those rules and to find deterministic rules for the remaining variables, which require downscaling, e.g. precipitation or near surface specifc humidity. To accomplish that, we broaden the search by allowing for interdependencies between different atmospheric parameters, non-linear relations, non-local and time-lagged relations. To cope with the vast number of possible solutions, we use genetic programming, a method from machine learning, which is based on the principles of natural evolution. We are currently working with GPLAB, a Genetic Programming toolbox for Matlab. At first we have tested the GP system to retrieve the known physical rule for downscaling surface pressure, i.e. the hydrostatic equation, from our training data. We have found this to be a simple task to the GP system. Furthermore we have improved accuracy and efficiency of the GP solution by implementing constant variation and optimization as genetic operators. Next we have worked on an improvement of the downscaling rule for the two-meter-temperature. We have added an if-function with four input arguments to the function set. Since this has shown to increase bloat we have additionally modified our fitness function by including penalty terms for both the size of the solutions and the number intron nodes, i.e program parts that are never evaluated. Starting from the known downscaling rule for the two-meter temperature, which linearly exploits the orography anomalies allowed or disallowed by a certain temperature gradient, our GP system has been able to find an improvement. The rule produced by the GP clearly shows a better performance concerning the reproduced small-scale variability.

Thermal conductivity study of warm dense matter by differential heating on LCLS and Titan

NASA Astrophysics Data System (ADS)

Hill, M.; McKelvey, A.; Jiang, S.; Shepherd, R.; Hau-Riege, S.; Whitley, H.; Sterne, P.; Hamel, S.; Collins, G.; Ping, Y.; Brown, C.; Floyd, E.; Fyrth, J.; Hoarty, D.; Hua, R.; Bailly-Grandvaux, M.; Beg, F.; Cho, B.; Kim, M.; Lee, J.; Lee, H.; Galtier, E.

2017-10-01

A differential heating platform has been developed for thermal conduction study, where a temperature gradient is induced and subsequent heat flow is probed by time-resolved diagnostics. Multiple experiment using this platform have been carried out at LCLS-MEC and Titan laser facilities for warm dense Al, Fe, amorphous carbon and diamond. Two single-shot time-resolved diagnostics are employed, SOP (streaked optical pyrometry) for surface temperature and FDI (Fourier Domain Interferometry) for surface expansion. Both diagnostics provided excellent data to constrain release equation-of-state (EOS) and thermal conductivity. Data sets with varying target thickness and comparison between simulations with different thermal conductivity models are presented. This work was performed under DOE contract DE-AC52-07NA27344 with support from DOE OFES Early Career program and LLNL LDRD program.

Thermal conduction study of warm dense aluminum by proton differential heating

NASA Astrophysics Data System (ADS)

Ping, Y.; Kemp, G.; McKelvey, A.; Fernandez-Panella, A.; Shepherd, R.; Collins, G.; Sio, H.; King, J.; Freeman, R.; Hua, R.; McGuffey, C.; Kim, J.; Beg, F.

2016-10-01

A differential heating platform has been developed for thermal conduction study (Ping et al. PoP 2015), where a temperature gradient is induced and subsequent heat flow is probed by time-resolved diagnostics. An experiment using proton differential heating has been carried out at Titan laser for Au/Al targets. Two single-shot time-resolved diagnostics are employed, SOP (streaked optical pyrometry) for surface temperature and FDI (Fourier Domain Interferometry) for surface expansion. Hydrodynamic simulations show that after 15ps, absorption in underdense plasma needs to be taken into account to correctly interpret SOP data. Comparison between simulations with different thermal conductivity models and a set of data with varying target thickness will be presented. This work was performed under DOE contract DE-AC52-07NA27344 with support from OFES Early Career program and LLNL LDRD program.

Engaging Communities to Understand and Adapt to Environmental Changes with The GLOBE Program

NASA Astrophysics Data System (ADS)

Wegner, K.; Malmberg, J. S.; Murphy, T.; Mauriello, H.

2015-12-01

During the past twenty years, The GLOBE Program (www.globe.gov) has connected scientists, K-12 students, teachers, and other stakeholders to "co-create" scientific understanding of their local, regional, and global environment in more than 110 countries. Through the support and collaboration of federal agencies- NASA, NSF, and NOAA- the community-driven GLOBE database has more than 130 million Earth science measurements (atmosphere, biosphere, hydrosphere, and pedosphere) that align with the USGCRP's indicators of climate change, such as air and surface temperature (Indicator: Global Surface Temperature), land cover (Indicators: 1) Forest Cover; 2) Grassland, Shrubland, and Pasture Cover), and plant phenology (Indicator: Start of Spring). GLOBE contributes to climate literacy while encouraging community members of all ages to enrich their scientific understanding, define issues of local relevance, and engage in broader action, such as regional and global science campaigns. In this session, we will present case studies of how GLOBE data has been used to inspire "homegrown" research campaigns such as the GLOBE Surface Temperature Campaign and European Aerosols Campaign, as well as solution-based action in response to environmental changes, including the development of a mosquito protocol in Thailand and across Africa and a toad service project in the Czech Republic. We will also discuss some of the initiatives we have led as a program in order to promote and share local and regional community-led efforts with our worldwide GLOBE community, as well as some of the challenges and opportunities presented by supporting climate research.

Implicit Coupling Approach for Simulation of Charring Carbon Ablators

NASA Technical Reports Server (NTRS)

Chen, Yih-Kanq; Gokcen, Tahir

2013-01-01

This study demonstrates that coupling of a material thermal response code and a flow solver with nonequilibrium gas/surface interaction for simulation of charring carbon ablators can be performed using an implicit approach. The material thermal response code used in this study is the three-dimensional version of Fully Implicit Ablation and Thermal response program, which predicts charring material thermal response and shape change on hypersonic space vehicles. The flow code solves the reacting Navier-Stokes equations using Data Parallel Line Relaxation method. Coupling between the material response and flow codes is performed by solving the surface mass balance in flow solver and the surface energy balance in material response code. Thus, the material surface recession is predicted in flow code, and the surface temperature and pyrolysis gas injection rate are computed in material response code. It is demonstrated that the time-lagged explicit approach is sufficient for simulations at low surface heating conditions, in which the surface ablation rate is not a strong function of the surface temperature. At elevated surface heating conditions, the implicit approach has to be taken, because the carbon ablation rate becomes a stiff function of the surface temperature, and thus the explicit approach appears to be inappropriate resulting in severe numerical oscillations of predicted surface temperature. Implicit coupling for simulation of arc-jet models is performed, and the predictions are compared with measured data. Implicit coupling for trajectory based simulation of Stardust fore-body heat shield is also conducted. The predicted stagnation point total recession is compared with that predicted using the chemical equilibrium surface assumption

Advanced high temperature instrument for hot section research applications

NASA Technical Reports Server (NTRS)

Englund, D. R.; Seasholtz, R. G.

1989-01-01

Programs to develop research instrumentation for use in turbine engine hot sections are described. These programs were initiated to provide improved measurements capability as support for a multidisciplinary effort to establish technology leading to improved hot section durability. Specific measurement systems described here include heat flux sensors, a dynamic gas temperature measuring system, laser anemometry for hot section applications, an optical system for viewing the interior of a combustor during operation, thin film sensors for surface temperature and strain measurements, and high temperature strain measuring systems. The state of development of these sensors and measuring systems is described, and, in some cases, examples of measurements made with these instruments are shown. Work done at the NASA Lewis Research Center and at various contract and grant facilities is covered.

Tile Surface Thermocouple Measurement Challenges from the Orbiter Boundary Layer Transition Flight Experiment

NASA Technical Reports Server (NTRS)

Campbell, Charles H.; Berger, Karen; Anderson, Brian

2012-01-01

Hypersonic entry flight testing motivated by efforts seeking to characterize boundary layer transition on the Space Shuttle Orbiters have identified challenges in our ability to acquire high quality quantitative surface temperature measurements versus time. Five missions near the end of the Space Shuttle Program implemented a tile surface protuberance as a boundary layer trip together with tile surface thermocouples to capture temperature measurements during entry. Similar engineering implementations of these measurements on Discovery and Endeavor demonstrated unexpected measurement voltage response during the high heating portion of the entry trajectory. An assessment has been performed to characterize possible causes of the issues experienced during STS-119, STS-128, STS-131, STS-133 and STS-134 as well as similar issues encountered during other orbiter entries.

Validation of Surface Bio-Optical Properties in the Gulf of Maine as a Means for Improving Satellite Primary Production Estimates. Chapter 4

NASA Technical Reports Server (NTRS)

Balch, William M.

2001-01-01

One of the greatest challenges in providing sea-truth data for various ocean color sensors is climatology. This is particularly true in the Gulf of Maine since it is cloudy and foggy more than it is clear; the climatology shows on average, about one in four to five days has clear skies with clear days slightly more frequent in the late summer and early fall. Our strategy has been to use a ship of opportunity where one has choice of the sampling days. This provides much better flexibility to sample during clear periods with good satellite coverage. Our Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) contract has been to use the M/S Scotia Prince ferry as a ship of opportunity, running between Portland, Maine and Yarmouth, NS. Measurements include continuous, surface, along-track fluorescence, two independent measures of backscattering, total light scattering, absorption, beam attenuation, above-water remote sensing reflectance, calcite-dependent light scattering, temperature, and salinity. Expendable bathythermography (XBT) drops allow acquisition of vertical temperature information, useful for defining isopycnal slope, which affects primary production. These data are comparable to a previous program from early 1982, where a ship of opportunity program (SOOP) was run on the truck ferry, M/V Marine Evangeline, which ran along the same transect. These surface data were combined with satellite-derived sea surface temperature fields to examine the Maine coastal current. Unfortunately, this program stopped in 1982. The ongoing SIMBIOS results will dovetail nicely with the previous work (which also had Coastal Zone Color Scanner (CZCS) coverage) for looking at any long-term changes in the Gulf of Maine hydrography, bio-optics, and biogeochemistry.

Experimental Investigation of Turbine Vane Heat Transfer for Alternative Fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nix, Andrew Carl

The focus of this program was to experimentally investigate advanced gas turbine cooling schemes and the effects of and factors that contribute to surface deposition from particulate matter found in coal syngas exhaust flows on turbine airfoil heat transfer and film cooling, as well as to characterize surface roughness and determine the effects of surface deposition on turbine components. The program was a comprehensive, multi-disciplinary collaborative effort between aero-thermal and materials faculty researchers and the Department of Energy, National Energy Technology Laboratory (NETL). The primary technical objectives of the program were to evaluate the effects of combustion of syngas fuelsmore » on heat transfer to turbine vanes and blades in land-based power generation gas turbine engines. The primary questions to be answered by this investigation were; What are the factors that contribute to particulate deposition on film cooled gas turbine components? An experimental program was performed in a high-temperature and pressure combustion rig at the DOE NETL; What is the effect of coal syngas combustion and surface deposition on turbine airfoil film cooling? Deposition of particulate matter from the combustion gases can block film cooling holes, decreasing the flow of the film coolant and the film cooling effectiveness; How does surface deposition from coal syngas combustion affect turbine surface roughness? Increased surface roughness can increase aerodynamic losses and result in decreased turbine hot section efficiency, increasing engine fuel consumption to maintain desired power output. Convective heat transfer is also greatly affected by the surface roughness of the airfoil surface; Is there any significant effect of surface deposition or erosion on integrity of turbine airfoil thermal barrier coatings (TBC) and do surface deposits react with the TBC in any way to decrease its thermal insulating capability? Spallation and erosion of TBC is a persistent problem in modern turbine engines; and What advancements in film cooling hole geometry and design can increase effectiveness of film cooling in turbines burning high-hydrogen coal syngas due to the higher heat loads and mass flow rates of the core flow? Experimental and numerical investigations of advanced cooling geometries that can improve resistance to surface deposition were performed. The answers to these questions were investigated through experimental measurements of turbine blade surface temperature and coolant coverage (via infrared camera images and thermocouples) and time-varying surface roughness in the NETL high-pressure combustion rig with accelerated, simulated surface deposition and advanced cooling hole concepts, coupled with detailed materials analysis and characterization using conventional methods of Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), 3-D Surface Topography (using a 3-D stylus profilometer). Detailed surface temperatures and cooling effectiveness could not be measured due to issues with the NETL infrared camera system. In collaboration with faculty startup funding from the principal investigator, experimental and numerical investigations were performed of an advanced film cooling hole geometry, the anti-vortex hole (AVH), focusing on improving cooling effectiveness and decreasing the counter-rotating vortex of conventional cooling holes which can entrain mainstream particulate matter to the surface. The potential benefit of this program is in gaining a fundamental understanding of how the use of alternative fuels will effect the operation of modern gas turbine engines, providing valuable data for more effective cooling designs for future turbine systems utilizing alternative fuels.« less

Effects of temperature and surface contamination on D retention in ultrathin Li films on TZM

DOE PAGES

Capece, A. M.; Roszell, J. P.; Skinner, C. H.; ...

2014-10-29

Here in this work, we investigate deuterium retention at the Mo-Li interface by studying thin Li films three monolayers thick on a TZM Mo alloy. Li films at temperatures between 315 and 460 K were exposed to a deuterium ion beam and D retention was measured using temperature programmed desorption. In the absence of oxygen, D is retained as LiD, and the relative amount of retained D decreases with increasing substrate temperature. In three-monolayer thick lithium oxide films, the amount of D retained was 2.5 times higher than the amount retained as LiD in the metallic Li film. However, oxygenmore » reduces the thermal stability of D in the film, causing D 2O and D 2 to be released from the surface at temperatures 150-200 K below the LiD decomposition temperature. These results highlight the importance of maintaining a metallic Li layer for high D retention in Li films on TZM at elevated temperatures.« less

Effects of temperature and surface contamination on D retention in ultrathin Li films on TZM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capece, A. M.; Roszell, J. P.; Skinner, C. H.

Here in this work, we investigate deuterium retention at the Mo-Li interface by studying thin Li films three monolayers thick on a TZM Mo alloy. Li films at temperatures between 315 and 460 K were exposed to a deuterium ion beam and D retention was measured using temperature programmed desorption. In the absence of oxygen, D is retained as LiD, and the relative amount of retained D decreases with increasing substrate temperature. In three-monolayer thick lithium oxide films, the amount of D retained was 2.5 times higher than the amount retained as LiD in the metallic Li film. However, oxygenmore » reduces the thermal stability of D in the film, causing D 2O and D 2 to be released from the surface at temperatures 150-200 K below the LiD decomposition temperature. These results highlight the importance of maintaining a metallic Li layer for high D retention in Li films on TZM at elevated temperatures.« less

Spectral Dependence of Stratified Electrothermal Instability in Tamped Aluminum 6061 with Current in a Skin Layer

NASA Astrophysics Data System (ADS)

Bauer, Bruno; Hutchinson, Trevor; Awe, Thomas

2017-10-01

The stratified electrothermal instability (ETI) was recently observed on the surface of thick aluminum 6061 pulsed with rapidly rising lineal current density (3 ×1015 A m-1s-1) for 70 ns. A transparent 70- μm-thick Parylene-N coating tamped the aluminum expansion and suppressed surface plasma. The evolution of the aluminum surface emission pattern was recorded with time-resolved microscopy (3- μm resolution). The images were converted into a series of blackbody surface-temperature maps. Analysis of these temperature maps provides information on the evolution of temperature fluctuations, as a function of axial wavelength and azimuthal width. Perturbations with axial wavelength longer than 20 μm grow, while those with axial wavelength shorter than 10 μm decay. Comparing the spectral dependence of growth/decay rates with MHD simulations could test the modeling of ETI positive feedback and of damping by thermal conduction. Work supported by Sandia National Laboratories LDRD program, PO 1742766.

Gas-phase measurements of combustion interaction with materials for radiation-cooled chambers

NASA Technical Reports Server (NTRS)

Barlow, R. S.; Lucht, R. P.; Jassowski, D. M.; Rosenberg, S. D.

1991-01-01

Foil samples of Ir and Pt are exposed to combustion products in a controlled premixed environment at atmospheric pressure. Electrical heating of the foil samples is used to control the surface temperature and to elevate it above the radiative equilibrium temperature within the test apparatus. Profiles of temperature and OH concentration in the boundary layer adjacent to the specimen surface are measured by laser-induced fluorescence. Measured OH concentrations are significantly higher than equilibrium concentrations calculated for the known mixture ratio and the measured temperature profiles. This result indicates that superequilibrium concentrations of H-atoms and O-atoms are also present in the boundary layer, due to partial equilibrium of the rapid binary reactions of the H2/O2 chemical kinetic system. These experiments are conducted as part of a research program to investigate fundamental aspects of the interaction of combustion gases with advanced high-temperature materials for radiation-cooled thrusters.

Theoretical research program to study transition metal trimers and embedded clusters

NASA Technical Reports Server (NTRS)

Walch, Stephen P.

1987-01-01

The results of ab-initio calculations are reported for (1) small transition metal clusters and (2) potential energy surfaces for chemical reactions important in hydrogen combustion and high temperature air chemistry.

Development of a satellite microwave radiometer to sense the surface temperature of the world oceans

NASA Technical Reports Server (NTRS)

Hidy, G. M.; Hall, W. F.; Hardy, W. N.; Ho, W. W.; Jones, A. C.; Love, A. W.; Vannmell, M. J.; Wang, H. H.; Wheeler, A. E.

1972-01-01

A proposed S-band radiometer for determining the ocean surface temperature with an absolute accuracy of + or - 1 Kelvin and a resolution of + or - .1 Kelvin was placed under the Advanced Applications Flight Experiment for further development into Nimbus readiness state. The results of assessing the following are described: effects due to the state of the sea surface, effects caused by the intervening atmosphere, and effects associated with imperfections in the instrument itself. An extensive sea truth program is also described for correlation of aircraft test flight measurements or of satellite remote measurement to in-situ data. An improved radiometer design is a modified Dicke-switch type with temperature stabilized, microwave integrated circuit, front-end and with a pulsed injection-noise nulling system. The radiometer has a multimode rectangular horn antenna with very low ohmic losses and a beam efficiency of 98% or better.

Microwave brightness temperature of a windblown sea

NASA Technical Reports Server (NTRS)

Hall, F. G.

1972-01-01

A mathematical model is developed for the apparent temperature of the sea at all microwave frequencies. The model is a numerical model in which both the clear water structure and white water are accounted for as a function of wind speed. The model produces results similar to Stogryn's model at 19.35 GHz for wind speeds less than 8 m/sec; it can use radiosonde data to calculate atmospheric effects and can incorporate an empirically determined antenna gain pattern. The corresponding computer program is of modular design and the logic of the main program is capable of treating a horizontally inhomogeneous surface or atmosphere. It is shown that a variation of microwave brightness temperature with zenith angle is necessary to produce the wind sensitivity of the horizontally polarized brightness temperature; the variation of sky temperature with frequency is sufficient to produce a frequency dependent wind sensitivity.

Columbia: The first five flights entry heating data series. Volume 4: The lower windward wing 50 percent and 80 percent semispans

NASA Technical Reports Server (NTRS)

Williams, S. D.

1983-01-01

Entry heating flight data and wind tunnel data on the lower wing 50% and 80% Semi-Spans are presented for the first five flights of the Space Shuttle Orbiter. The heating rate data is presented in terms of normalized film heat transfer coefficients as a function of angle-of-attack, Mach number, and Normal Shock Reynolds number. The surface heating rates and temperatures were obtained via the JSC NONLIN/INVERSE computer program. Time history plots of the surface heating rates and temperatures are also presented.

A Study of Surface Temperatures, Clouds and Net Radiation

NASA Technical Reports Server (NTRS)

Dhuria, Harbans

1996-01-01

This study focused on the seasonal relationships and interactions of climate parameters such as the surface temperatures, net radiation, long wave flux, short wave flux, and clouds on a global basis. Five years of observations (December 1984 to November 1989) from the Earth Radiation Budget Experiment (ERBE) and the International Satellite Cloud Climatology Program (ISCCP) were used to study both seasonal variations and interannual variations by use of a basic radiation budget equation. In addition, the study was extended to include an analysis of the cloud forcing due El-Nino's impact on the ERBE parameters.

ALMA observation of Ceres' Surface Temperature.

NASA Astrophysics Data System (ADS)

Titus, T. N.; Li, J. Y.; Sykes, M. V.; Ip, W. H.; Lai, I.; Moullet, A.

2016-12-01

Ceres, the largest object in the main asteroid belt, has been mapped by the Dawn spacecraft. The mapping includes measuring surface temperatures using the Visible and Infrared (VIR) spectrometer at high spatial resolution. However, the VIR instrument has a long wavelength cutoff at 5 μm, which prevents the accurate measurement of surface temperatures below 180 K. This restricts temperature determinations to low and mid-latitudes at mid-day. Observations from the Atacama Large Millimeter/submillimeter Array (ALMA) [1], while having lower spatial resolution, are sensitive to the full range of surface temperatures that are expected at Ceres. Forty reconstructed images at 75 km/beam resolution were acquired of Ceres that were consistent with a low thermal inertia surface. The diurnal temperature profiles were compared to the KRC thermal model [2, 3], which has been extensively used for Mars [e.g. 4, 5]. Variations in temperature as a function of local time are observed and are compared to predictions from the KRC model. The model temperatures are converted to radiance (Jy/Steradian) and are corrected for near-surface thermal gradients and limb effects for comparison to observations. Initial analysis is consistent with the presence of near-surface water ice in the north polar region. The edge of the ice table is between 50° and 70° North Latitude, consistent with the enhanced detection of hydrogen by the Dawn GRaND instrument [6]. Further analysis will be presented. This work is supported by the NASA Solar System Observations Program. References: [1] Wootten A. et al. (2015) IAU General Assembly, Meeting #29, #2237199 [2] Kieffer, H. H., et al. (1977) JGR, 82, 4249-4291. [3] Kieffer, Hugh H., (2013) Journal of Geophysical Research: Planets, 118(3), 451-470. [4] Titus, T. N., H. H. Kieffer, and P. N. Christensen (2003) Science, 299, 1048-1051. [5] Fergason, R. L. et al. (2012) Space Sci. Rev, 170, 739-773[6] Prettyman, T. et al. (2016) LPSC 47, #2228.

Sensitivity of potential evapotranspiration and simulated flow to varying meteorological inputs, Salt Creek watershed, DuPage County, Illinois

USGS Publications Warehouse

Whitbeck, David E.

2006-01-01

The Lamoreux Potential Evapotranspiration (LXPET) Program computes potential evapotranspiration (PET) using inputs from four different meteorological sources: temperature, dewpoint, wind speed, and solar radiation. PET and the same four meteorological inputs are used with precipitation data in the Hydrological Simulation Program-Fortran (HSPF) to simulate streamflow in the Salt Creek watershed, DuPage County, Illinois. Streamflows from HSPF are routed with the Full Equations (FEQ) model to determine water-surface elevations. Consequently, variations in meteorological inputs have potential to propagate through many calculations. Sensitivity of PET to variation was simulated by increasing the meteorological input values by 20, 40, and 60 percent and evaluating the change in the calculated PET. Increases in temperatures produced the greatest percent changes, followed by increases in solar radiation, dewpoint, and then wind speed. Additional sensitivity of PET was considered for shifts in input temperatures and dewpoints by absolute differences of ?10, ?20, and ?30 degrees Fahrenheit (degF). Again, changes in input temperatures produced the greatest differences in PET. Sensitivity of streamflow simulated by HSPF was evaluated for 20-percent increases in meteorological inputs. These simulations showed that increases in temperature produced the greatest change in flow. Finally, peak water-surface elevations for nine storm events were compared among unmodified meteorological inputs and inputs with values predicted 6, 24, and 48 hours preceding the simulated peak. Results of this study can be applied to determine how errors specific to a hydrologic system will affect computations of system streamflow and water-surface elevations.

Water adsorption on the Fe3O4(111) surface: dissociation and network formation.

PubMed

Zaki, Eman; Mirabella, Francesca; Ivars-Barceló, Francisco; Seifert, Jan; Carey, Spencer; Shaikhutdinov, Shamil; Freund, Hans-Joachim; Li, Xiaoke; Paier, Joachim; Sauer, Joachim

2018-06-13

We monitored adsorption of water on a well-defined Fe3O4(111) film surface at different temperatures as a function of coverage using infrared reflection-absorption spectroscopy, temperature programmed desorption, and single crystal adsorption calorimetry. Additionally, density functional theory was employed using a Fe3O4(111)-(2 × 2) slab model to generate 15 energy minimum structures for various coverages. Corresponding vibrational properties of the adsorbed water species were also computed. The results show that water molecules readily dissociate on regular surface Fetet1-O ion pairs to form "monomers", i.e., terminal Fe-OH and surface OH groups. Further water molecules adsorb on the hydroxyl covered surface non-dissociatively and form "dimers" and larger oligomers, which ultimately assemble into an ordered (2 × 2) hydrogen-bonded network structure with increasing coverage prior to the formation of a solid water film.

NASA Cold Land Processes Experiment (CLPX 2002/03): Field measurements of snowpack properties and soil moisture

Treesearch

Kelly Elder; Don Cline; Glen E. Liston; Richard Armstrong

2009-01-01

A field measurement program was undertaken as part NASA's Cold Land Processes Experiment (CLPX). Extensive snowpack and soil measurements were taken at field sites in Colorado over four study periods during the two study years (2002 and 2003). Measurements included snow depth, density, temperature, grain type and size, surface wetness, surface roughness, and...

An atlas of monthly mean distributions of SSMI surface wind speed, AVHRR/2 sea surface temperature, AMI surface wind velocity, TOPEX/POSEIDON sea surface height, and ECMWF surface wind velocity during 1993

NASA Technical Reports Server (NTRS)

Halpern, D.; Fu, L.; Knauss, W.; Pihos, G.; Brown, O.; Freilich, M.; Wentz, F.

1995-01-01

The following monthly mean global distributions for 1993 are presented with a common color scale and geographical map: 10-m height wind speed estimated from the Special Sensor Microwave Imager (SSMI) on a United States (U.S.) Air Force Defense Meteorological Satellite Program (DMSP) spacecraft; sea surface temperature estimated from the Advanced Very High Resolution Radiometer (AVHRR/2) on a U.S. National Oceanic and Atmospheric Administration (NOAA) satellite; 10-m height wind speed and direction estimated from the Active Microwave Instrument (AMI) on the European Space Agency (ESA) European Remote Sensing (ERS-1) satellite; sea surface height estimated from the joint U.S.-France Topography Experiment (TOPEX)/POSEIDON spacecraft; and 10-m height wind speed and direction produced by the European Center for Medium-Range Weather Forecasting (ECMWF). Charts of annual mean, monthly mean, and sampling distributions are displayed.

TACT1- TRANSIENT THERMAL ANALYSIS OF A COOLED TURBINE BLADE OR VANE EQUIPPED WITH A COOLANT INSERT

NASA Technical Reports Server (NTRS)

Gaugler, R. E.

1994-01-01

As turbine-engine core operating conditions become more severe, designers must develop more effective means of cooling blades and vanes. In order to design reliable, cooled turbine blades, advanced transient thermal calculation techniques are required. The TACT1 computer program was developed to perform transient and steady-state heat-transfer and coolant-flow analyses for cooled blades, given the outside hot-gas boundary condition, the coolant inlet conditions, the geometry of the blade shell, and the cooling configuration. TACT1 can analyze turbine blades, or vanes, equipped with a central coolant-plenum insert from which coolant-air impinges on the inner surface of the blade shell. Coolant-side heat-transfer coefficients are calculated with the heat transfer mode at each station being user specified as either impingement with crossflow, forced convection channel flow, or forced convection over pin fins. A limited capability to handle film cooling is also available in the program. The TACT1 program solves for the blade temperature distribution using a transient energy equation for each node. The nodal energy balances are linearized, one-dimensional, heat-conduction equations which are applied at the wall-outer-surface node, at the junction of the cladding and the metal node, and at the wall-inner-surface node. At the mid-metal node a linear, three-dimensional, heat-conduction equation is used. Similarly, the coolant pressure distribution is determined by solving the set of transfer momentum equations for the one-dimensional flow between adjacent fluid nodes. In the coolant channel, energy and momentum equations for one-dimensional compressible flow, including friction and heat transfer, are used for the elemental channel length between two coolant nodes. The TACT1 program first obtains a steady-state solution using iterative calculations to obtain convergence of stable temperatures, pressures, coolant-flow split, and overall coolant mass balance. Transient calculations are based on the steady-state solutions obtained. Input to the TACT1 program includes a geometrical description of the blade and insert, the nodal spacing to be used, and the boundary conditions describing the outside hot-gas and the coolant-inlet conditions. The program output includes the value of nodal temperatures and pressures at each iteration. The final solution output includes the temperature at each coolant node, and the coolant flow rates and Reynolds numbers. This program is written in FORTRAN IV for batch execution and has been implemented on an IBM 360 computer with a central memory requirement of approximately 480K of 8 bit bytes. The TACT1 program was developed in 1978.

Surface temperature measurements of a levitated water drop during laser irradiation

NASA Astrophysics Data System (ADS)

Brownell, Cody; Tracey, Timothy

2016-11-01

Simulation of high energy laser propagation and scattering in the maritime environment is problematic, due to the high liklihood of turbulence, fog, and rain or sea spray within the beam path. Laser interactions with large water drops (diameters of approximately 1-mm), such as those found in a light rain, have received relatively less attention. In this regime a high energy laser will rapidly heat and vaporize a water drop as it traverses the beam path, but the exact heating / vaporization rate, its dependence on impurities, and ancillary effects on the drop or surroundings are unclear. In this work we present surface temperature measurements of a water drop obtained using a FLIR IR camera. The drop is acoustically levitated, and subject to a continuous wave laser with a wavelength of 1070-nm and a mean irradiance of approximately 500 W/cm2. These measurements show that the steady-state surface temperature of the drop is well below the saturation temperature, yet based on the time history of the drop volume vaporization begins almost immediately upon laser strike. Inferences on the turbulence characteristics within the drop are also made from measurements of the fluctuations in the surface temperature. Supported by ONR, HEL-JTO, and USNA Trident Scholar Program.

Needs, opportunities and strategies for a long-term oceanic sciences satellite program

NASA Technical Reports Server (NTRS)

Ruttenberg, S. (Editor)

1981-01-01

Several areas of the National Oceanic Satellite System are addressed including Satellite-borne communication systems, subsurface remote sensing, data coordination, color scanners, formatting important historical data sets, and sea surface temperature observations.

Metals and Ceramics Division Materials Sciences Program. Annual progress report for period ending December 31, 1985

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stiegler, J.O.

1986-06-01

The report is divided into the following: structural characterization, high-temperature alloy research, structural ceramics, radiation effects, structure and properties of surfaces and interfaces, and collaborative research centers. (DLC)

Heat Flux and Wall Temperature Estimates for the NASA Langley HIFiRE Direct Connect Rig

NASA Technical Reports Server (NTRS)

Cuda, Vincent, Jr.; Hass, Neal E.

2010-01-01

An objective of the Hypersonic International Flight Research Experimentation (HIFiRE) Program Flight 2 is to provide validation data for high enthalpy scramjet prediction tools through a single flight test and accompanying ground tests of the HIFiRE Direct Connect Rig (HDCR) tested in the NASA LaRC Arc Heated Scramjet Test Facility (AHSTF). The HDCR is a full-scale, copper heat sink structure designed to simulate the isolator entrance conditions and isolator, pilot, and combustor section of the HIFiRE flight test experiment flowpath and is fully instrumented to assess combustion performance over a range of operating conditions simulating flight from Mach 5.5 to 8.5 and for various fueling schemes. As part of the instrumentation package, temperature and heat flux sensors were provided along the flowpath surface and also imbedded in the structure. The purpose of this paper is to demonstrate that the surface heat flux and wall temperature of the Zirconia coated copper wall can be obtained with a water-cooled heat flux gage and a sub-surface temperature measurement. An algorithm was developed which used these two measurements to reconstruct the surface conditions along the flowpath. Determinations of the surface conditions of the Zirconia coating were conducted for a variety of conditions.

Application of remote sensing to thermal pollution analysis. [satellite sea surface temperature measurement assessment

NASA Technical Reports Server (NTRS)

Hiser, H. W.; Lee, S. S.; Veziroglu, T. N.; Sengupta, S.

1975-01-01

A comprehensive numerical model development program for near-field thermal plume discharge and far field general circulation in coastal regions is being carried on at the University of Miami Clean Energy Research Institute. The objective of the program is to develop a generalized, three-dimensional, predictive model for thermal pollution studies. Two regions of specific application of the model are the power plants sites at the Biscayne Bay and Hutchinson Island area along the Florida coastline. Remote sensing from aircraft as well as satellites are used in parallel with in situ measurements to provide information needed for the development and verification of the mathematical model. This paper describes the efforts that have been made to identify problems and limitations of the presently available satellite data and to develop methods for enhancing and enlarging thermal infrared displays for mesoscale sea surface temperature measurements.

Experimental and theoretical studies of near-ground acoustic radiation propagation in the atmosphere

NASA Astrophysics Data System (ADS)

Belov, Vladimir V.; Burkatovskaya, Yuliya B.; Krasnenko, Nikolai P.; Rakov, Aleksandr S.; Rakov, Denis S.; Shamanaeva, Liudmila G.

2017-11-01

Results of experimental and theoretical studies of the process of near-ground propagation of monochromatic acoustic radiation on atmospheric paths from a source to a receiver taking into account the contribution of multiple scattering on fluctuations of atmospheric temperature and wind velocity, refraction of sound on the wind velocity and temperature gradients, and its reflection by the underlying surface for different models of the atmosphere depending the sound frequency, coefficient of reflection from the underlying surface, propagation distance, and source and receiver altitudes are presented. Calculations were performed by the Monte Carlo method using the local estimation algorithm by the computer program developed by the authors. Results of experimental investigations under controllable conditions are compared with theoretical estimates and results of analytical calculations for the Delany-Bazley impedance model. Satisfactory agreement of the data obtained confirms the correctness of the suggested computer program.

The 1979 Southeastern Virginia Urban Plume Study. Volume 1: Description of experiments and selected aircraft data

NASA Technical Reports Server (NTRS)

Gregory, G. L.; Lee, R. B., III; Mathis, J. J., Jr.

1981-01-01

The Southeastern Virginia Urban Plume Study (SEV-UPS) utilizes remote sensors and satellite platforms to monitor the Earth's environment and resources. SEV-UPS focuses on the application of specific remote sensors to the monitoring and study of specific air quality problems. The 1979 SEV-UPS field program was conducted with specific objectives: (1) to provide correlative data to evaluate the Laser Absorption spectrometer ozone remote sensors; (2) to demonstrate the utility of the sensor for the study of urban ozone problems; (3) to provide additional insights into air quality phenomena occuring in Southeastern Virginia; and (4) to compare measurement results of various in situ measurement platforms. The field program included monitoring from 12 surface stations, 4 aircraft, 2 tethered balloons, 2 radiosonde release sites, and numerous surface meteorological observation sites. The aircraft monitored 03, NO, NOX, Bscat, temperature, and dewpoint temperature.

Small Cold Temperature Instrument Packages

NASA Astrophysics Data System (ADS)

Clark, P. E.; Millar, P. S.; Yeh, P. S.; Feng, S.; Brigham, D.; Beaman, B.

We are developing a small cold temperature instrument package concept that integrates a cold temperature power system with ultra low temperature ultra low power electronics components and power supplies now under development into a 'cold temperature surface operational' version of a planetary surface instrument package. We are already in the process of developing a lower power lower temperature version for an instrument of mutual interest to SMD and ESMD to support the search for volatiles (the mass spectrometer VAPoR, Volatile Analysis by Pyrolysis of Regolith) both as a stand alone instrument and as part of an environmental monitoring package. We build on our previous work to develop strategies for incorporating Ultra Low Temperature/Ultra Low Power (ULT/ULP) electronics, lower voltage power supplies, as well as innovative thermal design concepts for instrument packages. Cryotesting has indicated that our small Si RHBD CMOS chips can deliver >80% of room temperature performance at 40K (nominal minimum lunar surface temperature). We leverage collaborations, past and current, with the JPL battery development program to increase power system efficiency in extreme environments. We harness advances in MOSFET technology that provide lower voltage thresholds for power switching circuits incorporated into our low voltage power supply concept. Conventional power conversion has a lower efficiency. Our low power circuit concept based on 'synchronous rectification' could produce stable voltages as low as 0.6 V with 85% efficiency. Our distributed micro-battery-based power supply concept incorporates cold temperature power supplies operating with a 4 V or 8 V battery. This work will allow us to provide guidelines for applying the low temperature, low power system approaches generically to the widest range of surface instruments.

Lignin-derived oxygenate reforming on a bimetallic surface: The reaction of benzaldehyde on Zn/Pt(111)

NASA Astrophysics Data System (ADS)

Shi, Daming; Vohs, John M.

2016-08-01

Temperature programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS) were used to characterize the adsorption and reaction of benzaldehyde (C6H5CHO) on hydrogen-covered Pt(111) and Zn-modified Pt(111) surfaces. Benzaldehyde was found to interact with Pt(111) via both the phenyl ring and carbonyl of the aldehyde group. This bonding configuration facilitates unselective decomposition of the benzaldehyde to produce CO, H2, and small hydrocarbon fragments at relatively low temperatures. On the other hand, benzaldehyde was found to bond to Zn-decorated Pt(111) surface exclusively via the carbonyl group in an η2(C, O) configuration, with the phenyl ring tilted away from the surface. This configuration weakens Csbnd O bond in the carbonyl facilitating its cleavage and helps prevent hydrogenation of the phenyl ring.

An atlas of monthly mean distributions of SSMI surface wind speed, ARGOS buoy drift, AVHRR/2 sea surface temperature, and ECMWF surface wind components during 1990

NASA Technical Reports Server (NTRS)

Halpern, D.; Knauss, W.; Brown, O.; Wentz, F.

1993-01-01

The following monthly mean global distributions for 1990 are proposed with a common color scale and geographical map: 10-m height wind speed estimated from the Special Sensor Microwave Imager (SSMI) on a United States (US) Air Force Defense Meteorological Satellite Program (DMSP) spacecraft; sea surface temperature estimated from the advanced very high resolution radiometer (AVHRR/2) on a U.S. National Oceanic and Atmospheric Administration (NOAA) spacecraft; Cartesian components of free drifting buoys which are tracked by the ARGOS navigation system on NOAA satellites; and Cartesian components on the 10-m height wind vector computed by the European Center for Medium-Range Weather Forecasting (ECMWF). Charts of monthly mean value, sampling distribution, and standard deviation values are displayed. Annual mean distributions are displayed.

An atlas of monthly mean distributions of SSMI surface wind speed, ARGOS buoy drift, AVHRR/2 sea surface temperature, and ECMWF surface wind components during 1991

NASA Technical Reports Server (NTRS)

Halpern, D.; Knauss, W.; Brown, O.; Wentz, F.

1993-01-01

The following monthly mean global distributions for 1991 are presented with a common color scale and geographical map: 10-m height wind speed estimated from the Special Sensor Microwave Imager (SSMI) on a United States Air Force Defense Meteorological Satellite Program (DMSP) spacecraft; sea surface temperature estimated from the advanced very high resolution radiometer (AVHRR/2) on a U.S. National Oceanic and Atmospheric Administration (NOAA) spacecraft; Cartesian components of free-drifting buoys which are tracked by the ARGOS navigation system on NOAA satellites; and Cartesian components of the 10-m height wind vector computed by the European Center for Medium-Range Weather Forecasting (ECMWF). Charts of monthly mean value, sampling distribution, and standard deviation value are displayed. Annual mean distributions are displayed.

Development of measurement simulation of the laser dew-point hygrometer using an optical fiber cable

NASA Astrophysics Data System (ADS)

Matsumoto, Shigeaki

2005-02-01

In order to improve the initial and the response times of the Laser Dew-Point Hygrometer (LDH), the measurement simulation was developed on the basis of the loop computation of the surface temperature of a gold plate for dew depostition, the quantity of deposited dew and the intensity of scattered light from the surface of the plate at time interval of 5 sec during measurement. A more detailed relationship between the surface temperature of the plate and the cooling current, and the time constant of the integrator in the control circuit of the LDH were introduced in the simulation program as a function of atmospheric temperature. The simulation was more close to the actual measurement by the LDH. The simulation results indicated the possibility of improving both the times of teh LDH by the increase of the sensitivity of dew and that of the mass transfer coefficient of dew deposited on the plate surface. It was concluded that the initial and the response times could be improved to below 100sec and 120 sec, respectively in the dew-point range at room temperature, that are almost half of the those times of the original LDH.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tam, M.S.; Antal, M.J. Jr.

A novel, three-step process for the production of high-quality activated carbons from macadamia nut shell and coconut shell charcoals is described. In this process the charcoal is (1) heated to a high temperature (carbonized), (2) oxidized in air following a stepwise heating program from low (ca. 450 K) to high (ca. 660 K) temperatures (oxygenated), and (3) heated again in an inert environment to a high temperature (activated). By use of this procedure, activated carbons with surface areas greater than 1,000 m{sub 2}/g are manufactured with an overall yield of 15% (based on the dry shell feed). Removal of carbonmore » mass by the development of mesopores and macropores is largely responsible for increases in the surface area of the carbons above 600 m{sub 2}/g. Thus, the surface area per gram of activated carbon can be represented by an inverse function of the yield for burnoffs between 15 and 60%. These findings are supported by mass-transfer calculations and pore-size distribution measurements. A kinetic model for gasification of carbon by oxygen, which provides for an Eley-Rideal type reaction of a surface oxide with oxygen in air, fits the measured gasification rates reasonably well over the temperature range of 550--660 K.« less

Feasibility of solar power for Mars

NASA Technical Reports Server (NTRS)

Appelbaum, Joseph; Landis, Geoffrey A.

1991-01-01

NASA, through Project Pathfinder, has put in place an advanced technology program to address future needs of manned space exploration. Included in the missions under study is the establishment of outposts on the surface of Mars. The Surface Power program in Pathfinder is aimed at providing photovoltaic array technology for such an application (as well as for the lunar surface). Another important application is for unmanned precursor missions, such as the photovoltaic-power aircraft, which will scout landing sites and investigate Mars geology for a 1 to 2 year mission without landing on the surface. Effective design and utilization of solar energy depend to a large extent on adequate knowledge of solar radiation characteristics in the region of solar energy system operation. The two major climatic components needed for photovoltaic system designs are the distributions of solar insolation and ambient temperature. These distributions for the Martian climate are given at the two Viking lander locations but can also be used, to the first approximation, for other latitudes. One of the most important results is that there is a large diffuse component of the insolation, even at high optical depth, so that solar energy system operation is still possible. If the power system is to continue to generate power even on high optical opacity days, it is thus important that the photovoltaic system be designed to collect diffuse irradiance as well as direct. In absence of long term insolation and temperature data for Mars, the data presented can be used until updated data are available. The ambient temperature data are given as measured directly by the temperature sensor; the insolation data are calculated from optical depth measurements of the atmosphere.

Thermographic analysis of surface damage in teeth

NASA Astrophysics Data System (ADS)

Conde-Contreras, M.; Bante-Guerra, J.; Hernandez-Garcia, E.; Hernandez, A. M.; Trujillo, S.; Quintana, P.; Alvarado-Gil, J. J.

2008-02-01

The analysis of the surface of teeth is an important field of research and technological development due to the importance of dental pieces in health and aesthetics. The presence of cracks as well as the etching effects on teeth surface, due to different chemical agents, affects not only the appearance of teeth but its integrity. In this work, laser thermography analysis of dental pieces with damage in the form of cracks is presented. The technique consists in the illumination of the surface at the center of the sample, using a 300 mW pulsed solid state laser beam focused with a gradium lens, and monitoring the spatial and temporal distribution of the temperature field. The heating of the sample is monitored using a focal plane array infrared camera, sensitive in the spectral range 7.5-13 μm with a noise equivalent temperature difference of 0.12°C. The data acquisition was performed by the PC firewire port using a PCI-8254R card and a home-made program in Labview 8.0 was used for data acquisition. The images were processed in a home-made linux program to obtain the experimental table values. Our results are compared with position and frequency scans obtained by infrared photothermal radiometry. It is shown that the crack in the tooth appears as an increase in the photothermal signal. In contrast, the thermographic image shows a more detailed structure in which close to the crack the temperature increases, but at the crack the signal falls.

Effect of the Mn oxidation state and lattice oxygen in Mn-based TiO2 catalysts on the low-temperature selective catalytic reduction of NO by NH3.

PubMed

Lee, Sang Moon; Park, Kwang Hee; Kim, Sung Su; Kwon, Dong Wook; Hong, Sung Chang

2012-09-01

TiO2-supported manganese oxide catalysts formed using different calcination temperatures were prepared by using the wet-impregnation method and were investigated for their activity in the low-temperature selective catalytic reduction (SCR) of NO by NH3 with respect to the Mn valence and lattice oxygen behavior. The surface and bulk properties of these catalysts were examined using Brunauer-Emmett-Teller (BET) surface area, X-ray diffraction (XRD), temperature-programmed reduction (TPR), and temperature-programmed desorption (TPD). Catalysts prepared using lower calcination temperatures, which contained Mn4+ displayed high SCR activity at low temperatures and possessed several acid sites and active oxygen. The TPD analysis determined that the Brönsted and Lewis acid sites in the Mn/TiO2 catalysts were important for the low-temperature SCR at 80-160 and 200-350 degrees C, respectively. In addition, the available lattice oxygen was important for attaining high NO to NO2 oxidation at low temperatures. Recently, various Mn catalysts have been evaluated as SCR catalysts. However, there have been no studies on the relationship of adsorption and desorption properties and behavior of lattice oxygen according to the valence state for manganese oxides (MnO(x)). Therefore, in this study, the catalysts were prepared by the wet-impregnation method at different calcination temperatures in order to show the difference of manganese oxidation state. These catalysts were then characterized using various physicochemical techniques, including BET, XRD, TPR, and TPD, to understand the structure, oxidation state, redox properties, and adsorption and desorption properties of the Mn/TiO2 catalysts.

Botswana water and surface energy balance research program. Part 2: Large scale moisture and passive microwaves

NASA Technical Reports Server (NTRS)

Vandegriend, A. A.; Owe, M.; Chang, A. T. C.

1992-01-01

The Botswana water and surface energy balance research program was developed to study and evaluate the integrated use of multispectral satellite remote sensing for monitoring the hydrological status of the Earth's surface. The research program consisted of two major, mutually related components: a surface energy balance modeling component, built around an extensive field campaign; and a passive microwave research component which consisted of a retrospective study of large scale moisture conditions and Nimbus scanning multichannel microwave radiometer microwave signatures. The integrated approach of both components are explained in general and activities performed within the passive microwave research component are summarized. The microwave theory is discussed taking into account: soil dielectric constant, emissivity, soil roughness effects, vegetation effects, optical depth, single scattering albedo, and wavelength effects. The study site is described. The soil moisture data and its processing are considered. The relation between observed large scale soil moisture and normalized brightness temperatures is discussed. Vegetation characteristics and inverse modeling of soil emissivity is considered.

Sea surface temperature estimates for the mid-Piacenzian Indian Ocean—Ocean Drilling Program sites 709, 716, 722, 754, 757, 758, and 763

USGS Publications Warehouse

Robinson, Marci M.; Dowsett, Harry J.; Stoll, Danielle K.

2018-01-30

Despite the wealth of global paleoclimate data available for the warm period in the middle of the Piacenzian Stage of the Pliocene Epoch (about 3.3 to 3.0 million years ago [Ma]; Dowsett and others, 2013, and references therein), the Indian Ocean has remained a region of sparse geographic coverage in terms of microfossil analysis. In an effort to characterize the surface Indian Ocean during this interval, we examined the planktic foraminifera from Ocean Drilling Program (ODP) sites 709, 716, 722, 754, 757, 758, and 763, encompassing a wide range of oceanographic conditions. We quantitatively analyzed the data for sea surface temperature (SST) estimation using both the modern analog technique (MAT) and a factor analytic transfer function. The data will contribute to the U.S. Geological Survey (USGS) Pliocene Research, Interpretation and Synoptic Mapping (PRISM) Project’s global SST reconstruction and climate model SST boundary condition for the mid-Piacenzian and will become part of the PRISM verification dataset designed to ground-truth Pliocene climate model simulations (Dowsett and others, 2013).

Surface Tension and Viscosity of SCN and SCN-acetone Alloys at Melting Points and Higher Temperatures Using Surface Light Scattering Spectrometer

NASA Technical Reports Server (NTRS)

Tin, Padetha; deGroh, Henry C., III.

2003-01-01

Succinonitrile has been and is being used extensively in NASA's Microgravity Materials Science and Fluid Physics programs and as well as in several ground-based and microgravity studies including the Isothermal Dendritic Growth Experiment (IDGE). Succinonitrile (SCN) is useful as a model for the study of metal solidification, although it is an organic material, it has a BCC crystal structure and solidifies dendriticly like a metal. It is also transparent and has a low melting point (58.08 C). Previous measurements of succinonitrile (SCN) and alloys of succinonitrile and acetone surface tensions are extremely limited. Using the Surface Light Scattering technique we have determined non invasively, the surface tension and viscosity of SCN and SCN-Acetone Alloys at different temperatures. This relatively new and unique technique has several advantages over the classical methods such as, it is non invasive, has good accuracy and measures the surface tension and viscosity simultaneously. The accuracy of interfacial energy values obtained from this technique is better than 2% and viscosity about 10 %. Succinonitrile and succinonitrile-acetone alloys are well-established model materials with several essential physical properties accurately known - except the liquid/vapor surface tension at different elevated temperatures. We will be presenting the experimentally determined liquid/vapor surface energy and liquid viscosity of succinonitrile and succinonitrile-acetone alloys in the temperature range from their melting point to around 100 C using this non-invasive technique. We will also discuss about the measurement technique and new developments of the Surface Light Scattering Spectrometer.

Analysis of Tank 38H (HTF-38-15-119, 127) Surface, Subsurface and Tank 43H (HTF-43-15-116, 117 and 118) Surface, Feed Pump Suction and Jet Suction Subsurface Supernatant Samples in Support of Enrichment, Corrosion Control and Salt Batch Planning Programs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oji, L.

Compositional feed limits have been established to ensure that a nuclear criticality event for the 2H and 3H Evaporators is not possible. The Enrichment Control Program (ECP) requires feed sampling to determine the equivalent enriched uranium content prior to transfer of waste other than recycle transfers (requires sampling to determine the equivalent enriched uranium at two locations in Tanks 38H and 43H every 26 weeks) The Corrosion Control Program (CCP) establishes concentration and temperature limits for key constituents and periodic sampling and analysis to confirm that waste supernate is within these limits. This report provides the results of analyses onmore » Tanks 38H and 43H surface and subsurface supernatant liquid samples in support of the ECP, the CCP, and the Salt Batch 10 Planning Program.« less

New Technology-Large-Area Three- Dimensional Surface Profiling Using Only Focused Air-Coupled Ultrasound-Given 1999 R&D 100 Award

NASA Technical Reports Server (NTRS)

Roth, Don J.; Kautz, Harold E.; Abel, Phillip B.; Whalen, Mike F.; Hendricks, J. Lynne; Bodis, James R.

2000-01-01

Surface topography, which significantly affects the performance of many industrial components, is normally measured with diamond-tip profilometry over small areas or with optical scattering methods over larger areas. To develop air-coupled surface profilometry, the NASA Glenn Research Center at Lewis Field initiated a Space Act Agreement with Sonix, Inc., through two Glenn programs, the Advanced High Temperature Engine Materials Program (HITEMP) and COMMTECH. The work resulted in quantitative surface topography profiles obtained using only high-frequency, focused ultrasonic pulses in air. The method is nondestructive, noninvasive, and noncontact, and it does not require light-reflective surfaces. Air surface profiling may be desirable when diamond-tip or laserbased methods are impractical, such as over large areas, when a significant depth range is required, or for curved surfaces. When the configuration is optimized, the method is reasonably rapid and all the quantitative analysis facilities are online, including two- and three-dimensional visualization, extreme value filtering (for faulty data), and leveling.

Multicolor pyrometer for materials processing in space

NASA Technical Reports Server (NTRS)

Frish, M. B.; Frank, J.; Baker, J. E.; Foutter, R. R.; Beerman, H.; Allen, M. G.

1990-01-01

This report documents the work performed by Physical Sciences Inc. (PSI), under contract to NASA JPL, during a 2.5-year SBIR Phase 2 Program. The program goals were to design, construct, and program a prototype passive imaging pyrometer capable of measuring, as accurately as possible, and controlling the temperature distribution across the surface of a moving object suspended in space. These goals were achieved and the instrument was delivered to JPL in November 1989. The pyrometer utilizes an optical system which operates at short wavelengths compared to the peak of the black-body spectrum for the temperature range of interest, thus minimizing errors associated with a lack of knowledge about the heated sample's emissivity. To cover temperatures from 900 to 2500 K, six wavelengths are available. The preferred wavelength for measurement of a particular temperature decreases as the temperature increases. Images at all six wavelengths are projected onto a single CCD camera concurrently. The camera and optical system have been calibrated to relate the measured intensity at each pixel to the temperature of the heated object. The output of the camera is digitized by a frame grabber installed in a personal computer and analyzed automatically to yield temperature information. The data can be used in a feedback loop to alter the status of computer-activated switches and thereby control a heating system.

Climate reconstruction from borehole temperatures influenced by groundwater flow

NASA Astrophysics Data System (ADS)

Kurylyk, B.; Irvine, D. J.; Tang, W.; Carey, S. K.; Ferguson, G. A. G.; Beltrami, H.; Bense, V.; McKenzie, J. M.; Taniguchi, M.

2017-12-01

Borehole climatology offers advantages over other climate reconstruction methods because further calibration steps are not required and heat is a ubiquitous subsurface property that can be measured from terrestrial boreholes. The basic theory underlying borehole climatology is that past surface air temperature signals are reflected in the ground surface temperature history and archived in subsurface temperature-depth profiles. High frequency surface temperature signals are attenuated in the shallow subsurface, whereas low frequency signals can be propagated to great depths. A limitation of analytical techniques to reconstruct climate signals from temperature profiles is that they generally require that heat flow be limited to conduction. Advection due to groundwater flow can thermally `contaminate' boreholes and result in temperature profiles being rejected for regional climate reconstructions. Although groundwater flow and climate change can result in contrasting or superimposed thermal disturbances, groundwater flow will not typically remove climate change signals in a subsurface thermal profile. Thus, climate reconstruction is still possible in the presence of groundwater flow if heat advection is accommodated in the conceptual and mathematical models. In this study, we derive a new analytical solution for reconstructing surface temperature history from borehole thermal profiles influenced by vertical groundwater flow. The boundary condition for the solution is composed of any number of sequential `ramps', i.e. periods with linear warming or cooling rates, during the instrumented and pre-observational periods. The boundary condition generation and analytical temperature modeling is conducted in a simple computer program. The method is applied to reconstruct climate in Winnipeg, Canada and Tokyo, Japan using temperature profiles recorded in hydrogeologically active environments. The results demonstrate that thermal disturbances due to groundwater flow and climate change must be considered in a holistic manner as opposed to isolating either perturbation as was done in prior analytical studies.

Navy High-Strength Steel Corrosion-Fatigue Modeling Program

DTIC Science & Technology

2006-10-01

interest. In the global analysis, the axial loading and residual stress (via the temperature profile discussed in the previous section) were applied to...developed based on observa- tions from analyses of axial load components with sinusoidally varying surface geometries. These observations indicated that...profile parameters (height and wavelength in each surface direction) and the applied axial loading . Stress Varies Sinusoidally 180° Out of Phase

Development of Advanced Thermal and Environmental Barrier Coatings Using a High-Heat-Flux Testing Approach

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

2003-01-01

The development of low conductivity, robust thermal and environmental barrier coatings requires advanced testing techniques that can accurately and effectively evaluate coating thermal conductivity and cyclic resistance at very high surface temperatures (up to 1700 C) under large thermal gradients. In this study, a laser high-heat-flux test approach is established for evaluating advanced low conductivity, high temperature capability thermal and environmental barrier coatings under the NASA Ultra Efficient Engine Technology (UEET) program. The test approach emphasizes the real-time monitoring and assessment of the coating thermal conductivity, which initially rises under the steady-state high temperature thermal gradient test due to coating sintering, and later drops under the cyclic thermal gradient test due to coating cracking/delamination. The coating system is then evaluated based on damage accumulation and failure after the combined steady-state and cyclic thermal gradient tests. The lattice and radiation thermal conductivity of advanced ceramic coatings can also be evaluated using laser heat-flux techniques. The external radiation resistance of the coating is assessed based on the measured specimen temperature response under a laser- heated intense radiation-flux source. The coating internal radiation contribution is investigated based on the measured apparent coating conductivity increases with the coating surface test temperature under large thermal gradient test conditions. Since an increased radiation contribution is observed at these very high surface test temperatures, by varying the laser heat-flux and coating average test temperature, the complex relation between the lattice and radiation conductivity as a function of surface and interface test temperature may be derived.

COSIM: A Finite-Difference Computer Model to Predict Ternary Concentration Profiles Associated With Oxidation and Interdiffusion of Overlay-Coated Substrates

NASA Technical Reports Server (NTRS)

Nesbitt, James A.

2001-01-01

A finite-difference computer program (COSIM) has been written which models the one-dimensional, diffusional transport associated with high-temperature oxidation and interdiffusion of overlay-coated substrates. The program predicts concentration profiles for up to three elements in the coating and substrate after various oxidation exposures. Surface recession due to solute loss is also predicted. Ternary cross terms and concentration-dependent diffusion coefficients are taken into account. The program also incorporates a previously-developed oxide growth and spalling model to simulate either isothermal or cyclic oxidation exposures. In addition to predicting concentration profiles after various oxidation exposures, the program can also be used to predict coating life based on a concentration dependent failure criterion (e.g., surface solute content drops to 2%). The computer code is written in FORTRAN and employs numerous subroutines to make the program flexible and easily modifiable to other coating oxidation problems.

Modeling of Lunar Dust Contamination Due to Plume Impingement

NASA Technical Reports Server (NTRS)

Woronowicz, Michael

2009-01-01

During the Apollo missions it became apparent that lunar dust was a significant hazard. Problems included: surface obscuration during landing sequence; abrasion damage to gouge faces and helmet visors; mechanism clogging; development of space suit pressurization leaks; loss of radiator heat rejection capabilities to the point where vulnerable equipment exceeded maximum survival temperature ratings; temporary vision and respiratory problems within the Apollo Lunar Module (LM). NASA Constellation Program features many system-level components, including the Altair Lunar Lander. Altair to endure longer periods at lunar surface conditions: Apollo LM, about three days; Altair, over seven months. Program managers interested in plume-generated dust transport onto thermal control surface radiators of the first Altair created by its own landing operations.

Elucidation of Active Sites for the Reaction of Ethanol on TiO 2 /Au(111)

DOE PAGES

Boyle, David T.; Wilke, Jeremy A.; Palomino, Robert M.; ...

2017-03-17

Obtaining a molecular-level understanding of the reaction of alcohols with heterogeneous model catalysts is critical for improving industrial catalytic processes, such as the production of H 2 from alcohols. Gold has been shown to be an excellent oxidation catalyst once oxygen is added to it. The use of reducible oxides provides a source of oxygen on Au(111) for the reaction of ethanol, which is easily regenerated in the presence of an oxygen background. In this work, ethanol operates as a probe molecule to investigate the role of Au(111), TiO 2 nanoparticles, and TiO 2/Au interfacial surface sites on the catalyticmore » properties of TiO 2/Au(111). Ultrahigh vacuum temperature-programmed desorption (TPD) studies with ethanol/Au(111) elucidate previously unreported adsorption sites for ethanol. Ethanol molecularly adsorbs to Au terrace sites, step edges, and undercoordinated kink sites with adsorption energies of -51.7, -55.8, and -65.1 kJ/mol, respectively. In a TPD coverage study of ethanol on TiO 2/Au(111) indicates ethanol undergoes dissociative adsorption to form H*(a) and CH 3CH 2O*(a) on the inverse model catalyst surface. The desorption temperature of low coverages of ethanol from TiO2/Au(111) (Tdes ≈ 235 K) is at an intermediate temperature between the desorption temperatures from bulk Au(111) and TiO 2(110), indicating both Au and TiO 2 play a role in the adsorption of ethanol. Both low-temperature adsorption and high-temperature reactions are studied and indicate that ethanol-derived products such as acetaldehyde and ethylene desorb from TiO 2/Au(111) at ~500 K. Here, we report the identification of catalytically active sites on TiO 2/Au(111) as interfacial sites between the oxide and Au(111) surface through the use of temperature-programmed desorption and infrared reflection absorption spectroscopy.« less

Elucidation of Active Sites for the Reaction of Ethanol on TiO 2 /Au(111)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyle, David T.; Wilke, Jeremy A.; Palomino, Robert M.

Obtaining a molecular-level understanding of the reaction of alcohols with heterogeneous model catalysts is critical for improving industrial catalytic processes, such as the production of H 2 from alcohols. Gold has been shown to be an excellent oxidation catalyst once oxygen is added to it. The use of reducible oxides provides a source of oxygen on Au(111) for the reaction of ethanol, which is easily regenerated in the presence of an oxygen background. In this work, ethanol operates as a probe molecule to investigate the role of Au(111), TiO 2 nanoparticles, and TiO 2/Au interfacial surface sites on the catalyticmore » properties of TiO 2/Au(111). Ultrahigh vacuum temperature-programmed desorption (TPD) studies with ethanol/Au(111) elucidate previously unreported adsorption sites for ethanol. Ethanol molecularly adsorbs to Au terrace sites, step edges, and undercoordinated kink sites with adsorption energies of -51.7, -55.8, and -65.1 kJ/mol, respectively. In a TPD coverage study of ethanol on TiO 2/Au(111) indicates ethanol undergoes dissociative adsorption to form H*(a) and CH 3CH 2O*(a) on the inverse model catalyst surface. The desorption temperature of low coverages of ethanol from TiO2/Au(111) (Tdes ≈ 235 K) is at an intermediate temperature between the desorption temperatures from bulk Au(111) and TiO 2(110), indicating both Au and TiO 2 play a role in the adsorption of ethanol. Both low-temperature adsorption and high-temperature reactions are studied and indicate that ethanol-derived products such as acetaldehyde and ethylene desorb from TiO 2/Au(111) at ~500 K. Here, we report the identification of catalytically active sites on TiO 2/Au(111) as interfacial sites between the oxide and Au(111) surface through the use of temperature-programmed desorption and infrared reflection absorption spectroscopy.« less

Continued Development of a Global Heat Transfer Measurement System at AEDC Hypervelocity Wind Tunnel 9

NASA Technical Reports Server (NTRS)

Kurits, Inna; Lewis, M. J.; Hamner, M. P.; Norris, Joseph D.

2007-01-01

Heat transfer rates are an extremely important consideration in the design of hypersonic vehicles such as atmospheric reentry vehicles. This paper describes the development of a data reduction methodology to evaluate global heat transfer rates using surface temperature-time histories measured with the temperature sensitive paint (TSP) system at AEDC Hypervelocity Wind Tunnel 9. As a part of this development effort, a scale model of the NASA Crew Exploration Vehicle (CEV) was painted with TSP and multiple sequences of high resolution images were acquired during a five run test program. Heat transfer calculation from TSP data in Tunnel 9 is challenging due to relatively long run times, high Reynolds number environment and the desire to utilize typical stainless steel wind tunnel models used for force and moment testing. An approach to reduce TSP data into convective heat flux was developed, taking into consideration the conditions listed above. Surface temperatures from high quality quantitative global temperature maps acquired with the TSP system were then used as an input into the algorithm. Preliminary comparison of the heat flux calculated using the TSP surface temperature data with the value calculated using the standard thermocouple data is reported.

International Coordination of and Contributions to Environmental Satellite Programs.

DTIC Science & Technology

1985-06-01

the international coordination of, and contributions to, environmental satellite programs. It re- views the background and history of international...Earth’s atmos- phere, surface temperature, cloud cover, water-ice boundaries, * and proton and electron flux near the Earth. They have the capability of...Islands Madagascar Sweden Chile Malaysia Switzerland China, People’s Rep. of Mali Syria Colombia Malta Tahiti Costa Rica Martinique Taiwan Curacao

Relative sliding durability of two candidate high temperature oxide fiber seal materials

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher; Steinetz, Bruce M.

1991-01-01

A test program to determine the relative sliding durability of two candidate ceramic fibers for high temperature sliding seal applications is described. Pin on disk tests were used to evaluate potential seal materials. Friction during the tests and fiber wear, indicated by the extent of fibers broken in a test bundle or yarn, was measured at the end of a test. In general, friction and wear increase with test temperature. This may be due to a reduction in fiber strength, a change in the surface chemistry at the fiber/counterface interface due to oxidation, adsorption and/or desorption of surface species and, to a lesser extent, an increase in counterface surface roughness due to oxidation at elevated temperatures. The relative fiber durability correlates with tensile strength indicating that tensile data, which is more readily available than sliding durability data, may be useful in predicting fiber wear behavior under various conditions. A simple model developed using dimensional analysis shows that the fiber durability is related to a dimensionless parameter which represents the ratio of the fiber strength to the fiber stresses imposed by sliding.

Air and ground temperatures along elevation and continentality gradients in Southern Norway

NASA Astrophysics Data System (ADS)

Farbrot, Herman; Hipp, Tobias; Etzelmüller, Bernd; Humlum, Ole; Isaksen, Ketil; Strand Ødegârd, Rune

2010-05-01

The modern southern boundary for Scandinavian permafrost is located in the mountains of Southern Norway. Permafrost and seasonal frost are considered key components of the cryosphere, and the climate-permafrost relation has acquired added importance with the increasing awareness and concern of rising air temperatures. The three-year research project CRYOLINK ("Permafrost and seasonal frost in southern Norway") aims at improving knowledge on past and present ground temperatures, seasonal frost, and distribution of mountain permafrost in Southern Norway by addressing the fundamental problem of heat transfer between the atmosphere and the ground surface. Hence, several shallow boreholes have been drilled, and a monitoring program to measure air and ground temperatures was started August 2008. The borehole areas (Juvvass, Jetta and Tron) are situated along a west-east transect and, hence, a continentality gradient, and each area provides boreholes at different elevations. Here we present the first year of air and ground temperatures from these sites and discuss the influence of air temperature and ground surface charcteristics (snow conditions, sediments/bedrock, vegetation) on ground temperatures.

1DTempPro: analyzing temperature profiles for groundwater/surface-water exchange.

PubMed

Voytek, Emily B; Drenkelfuss, Anja; Day-Lewis, Frederick D; Healy, Richard; Lane, John W; Werkema, Dale

2014-01-01

A new computer program, 1DTempPro, is presented for the analysis of vertical one-dimensional (1D) temperature profiles under saturated flow conditions. 1DTempPro is a graphical user interface to the U.S. Geological Survey code Variably Saturated 2-Dimensional Heat Transport (VS2DH), which numerically solves the flow and heat-transport equations. Pre- and postprocessor features allow the user to calibrate VS2DH models to estimate vertical groundwater/surface-water exchange and also hydraulic conductivity for cases where hydraulic head is known. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Columbia: The first 5 flights entry heating data series. Volume 5: The side fuselage and payload bay door

NASA Technical Reports Server (NTRS)

Williams, S. D.

1984-01-01

Entry heating flight data and wind tunnel data on the side fuselage and payload bay door, Z = 400 and 440 trace aft of X/L=0.2, for the first five flights of the Space Shuttle Orbiter are presented. The heating rate data are reviewed in terms of normalized film heat transfer coefficients as a function of angle of attack, Mach number, and normal shock Reynolds number. The surface heatings rates and temperatures were obtained by the JSC NONLIN/INVERSE computer program. Time history plots of the surface heating rates and temperatures are outlined.

Greenhouse models of the atmosphere of Titan.

NASA Technical Reports Server (NTRS)

Pollack, J. B.

1973-01-01

The greenhouse effect is calculated for a series of Titanian atmosphere models with different proportions of methane, hydrogen, helium, and ammonia. A computer program is used in temperature-structure calculations based on radiative-convective thermal transfer considerations. A brightness temperature spectrum is derived for Titan and is compared with available observational data. It is concluded that the greenhouse effect on Titan is generated by pressure-induced transitions of methane and hydrogen. The helium-to-hydrogen ratio is found to have a maximum of about 1.5. The surface pressure is estimated to be at least 0.4 atm, with a daytime temperature of about 155 K at the surface. The presence of methane clouds in the upper troposphere is indicated. The clouds have a significant optical depth in the visible, but not in the thermal, infrared.

In Situ UV-Visible Assessment of Iron-Based High-Temperature Water-Gas Shift Catalysts Promoted with Lanthana: An Extent of Reduction Study

DOE PAGES

Hallac, Basseem B.; Brown, Jared C.; Stavitski, Eli; ...

2018-02-04

Here, the extent of reduction of unsupported iron-based high-temperature water-gas shift catalysts with small (<5 wt %) lanthana contents was studied using UV-visible spectroscopy. Temperature- programmed reduction measurements showed that lanthana content higher than 0.5 wt % increased the extent of reduction to metallic Fe, while 0.5 wt % of lanthana facilitated the reduction to Fe 3O 4. In situ measurements on the iron oxide catalysts using mass and UV-visible spectroscopies permitted the quantification of the extent of reduction under temperature-programmed reduction and high-temperature water-gas shift conditions. The oxidation states were successfully calibrated against normalized absorbance spectra of visible lightmore » using the Kubelka-Munk theory. The normalized absorbance relative to the fully oxidized Fe 2O 3 increased as the extent of reduction increased. XANES suggested that the average bulk iron oxidation state during the water-gas shift reaction was Fe +2.57 for the catalyst with no lanthana and Fe +2.54 for the catalysts with 1 wt % lanthana. However, the UV-vis spectra suggest that the surface oxidation state of iron would be Fe +2.31 for the catalyst with 1 wt % lanthana if the oxidation state of iron in the catalyst with 0 wt % lanthana were Fe +2.57. The findings of this paper emphasize the importance of surface sensitive UV-visible spectroscopy for determining the extent of catalyst reduction during operation. Furthermore, the paper highlights the potential to use bench-scale UV-visible spectroscopy to study the surface chemistry of catalysts instead of less-available synchrotron X-ray radiation facilities.« less

In Situ UV-Visible Assessment of Iron-Based High-Temperature Water-Gas Shift Catalysts Promoted with Lanthana: An Extent of Reduction Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hallac, Basseem B.; Brown, Jared C.; Stavitski, Eli

Here, the extent of reduction of unsupported iron-based high-temperature water-gas shift catalysts with small (<5 wt %) lanthana contents was studied using UV-visible spectroscopy. Temperature- programmed reduction measurements showed that lanthana content higher than 0.5 wt % increased the extent of reduction to metallic Fe, while 0.5 wt % of lanthana facilitated the reduction to Fe 3O 4. In situ measurements on the iron oxide catalysts using mass and UV-visible spectroscopies permitted the quantification of the extent of reduction under temperature-programmed reduction and high-temperature water-gas shift conditions. The oxidation states were successfully calibrated against normalized absorbance spectra of visible lightmore » using the Kubelka-Munk theory. The normalized absorbance relative to the fully oxidized Fe 2O 3 increased as the extent of reduction increased. XANES suggested that the average bulk iron oxidation state during the water-gas shift reaction was Fe +2.57 for the catalyst with no lanthana and Fe +2.54 for the catalysts with 1 wt % lanthana. However, the UV-vis spectra suggest that the surface oxidation state of iron would be Fe +2.31 for the catalyst with 1 wt % lanthana if the oxidation state of iron in the catalyst with 0 wt % lanthana were Fe +2.57. The findings of this paper emphasize the importance of surface sensitive UV-visible spectroscopy for determining the extent of catalyst reduction during operation. Furthermore, the paper highlights the potential to use bench-scale UV-visible spectroscopy to study the surface chemistry of catalysts instead of less-available synchrotron X-ray radiation facilities.« less

Spreading of lithium on a stainless steel surface at room temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skinner, C. H.; Capece, A. M.; Roszell, J. P.

Lithium conditioned plasma facing surfaces have lowered recycling and enhanced plasma performance on many fusion devices and liquid lithium plasma facing components are under consideration for future machines. A key factor in the performance of liquid lithium components is the wetting by lithium of its container. We have observed the surface spreading of lithium from a mm-scale particle to adjacent stainless steel surfaces using a scanning Auger microprobe that has elemental discrimination. Here, the spreading of lithium occurred at room temperature (when lithium is a solid) from one location at a speed of 0.62 μm/day under ultrahigh vacuum conditions. Separatemore » experiments using temperature programmed desorption (TPD) investigated bonding energetics between monolayer-scale films of lithium and stainless steel. While multilayer lithium desorption from stainless steel begins to occur just above 500 K (E des = 1.54 eV), sub-monolayer Li desorption occurred in a TPD peak at 942 K (E des = 2.52 eV) indicating more energetically favorable lithium-stainless steel bonding (in the absence of an oxidation layer) than lithium lithium bonding.« less

Spreading of lithium on a stainless steel surface at room temperature

DOE PAGES

Skinner, C. H.; Capece, A. M.; Roszell, J. P.; ...

2015-11-10

Lithium conditioned plasma facing surfaces have lowered recycling and enhanced plasma performance on many fusion devices and liquid lithium plasma facing components are under consideration for future machines. A key factor in the performance of liquid lithium components is the wetting by lithium of its container. We have observed the surface spreading of lithium from a mm-scale particle to adjacent stainless steel surfaces using a scanning Auger microprobe that has elemental discrimination. Here, the spreading of lithium occurred at room temperature (when lithium is a solid) from one location at a speed of 0.62 μm/day under ultrahigh vacuum conditions. Separatemore » experiments using temperature programmed desorption (TPD) investigated bonding energetics between monolayer-scale films of lithium and stainless steel. While multilayer lithium desorption from stainless steel begins to occur just above 500 K (E des = 1.54 eV), sub-monolayer Li desorption occurred in a TPD peak at 942 K (E des = 2.52 eV) indicating more energetically favorable lithium-stainless steel bonding (in the absence of an oxidation layer) than lithium lithium bonding.« less

Spreading of lithium on a stainless steel surface at room temperature

NASA Astrophysics Data System (ADS)

Skinner, C. H.; Capece, A. M.; Roszell, J. P.; Koel, B. E.

2016-01-01

Lithium conditioned plasma facing surfaces have lowered recycling and enhanced plasma performance on many fusion devices and liquid lithium plasma facing components are under consideration for future machines. A key factor in the performance of liquid lithium components is the wetting by lithium of its container. We have observed the surface spreading of lithium from a mm-scale particle to adjacent stainless steel surfaces using a scanning Auger microprobe that has elemental discrimination. The spreading of lithium occurred at room temperature (when lithium is a solid) from one location at a speed of 0.62 μm/day under ultrahigh vacuum conditions. Separate experiments using temperature programmed desorption (TPD) investigated bonding energetics between monolayer-scale films of lithium and stainless steel. While multilayer lithium desorption from stainless steel begins to occur just above 500 K (Edes = 1.54 eV), sub-monolayer Li desorption occurred in a TPD peak at 942 K (Edes = 2.52 eV) indicating more energetically favorable lithium-stainless steel bonding (in the absence of an oxidation layer) than lithium-lithium bonding.

TranAir: A full-potential, solution-adaptive, rectangular grid code for predicting subsonic, transonic, and supersonic flows about arbitrary configurations. User's manual

NASA Technical Reports Server (NTRS)

Johnson, F. T.; Samant, S. S.; Bieterman, M. B.; Melvin, R. G.; Young, D. P.; Bussoletti, J. E.; Hilmes, C. L.

1992-01-01

The TranAir computer program calculates transonic flow about arbitrary configurations at subsonic, transonic, and supersonic freestream Mach numbers. TranAir solves the nonlinear full potential equations subject to a variety of boundary conditions modeling wakes, inlets, exhausts, porous walls, and impermeable surfaces. Regions with different total temperature and pressure can be represented. The user's manual describes how to run the TranAir program and its graphical support programs.

Roles of oxyanions in promoting the partial oxidation of styrene on Ag(110): nitrate, carbonate, sulfite, and sulfate.

PubMed

Zhou, Ling; Madix, Robert J

2010-11-02

The promotion roles of nitrate, carbonate, sulfite, and sulfate in oxidation of styrene on Ag(110) have been studied by means of temperature-programmed reaction spectroscopy (TPRS) and X-ray photoelectron spectroscopy (XPS). While isolated nitrate leads only to the secondary oxidation of styrene, a surface co-covered by nitrate, oxygen, and 0.1 ML cesium promotes a low-temperature epoxidation pathway. XPS indicates that adsorbed surface oxygen is the oxidant in this selective reaction pathway, and, though it affects the reactivity of the surface oxygen, nitrate is a spectator. Carbonate acts as an oxygen transfer agent and exhibits similar reactivity and selectivity as an oxidant for styrene as does atomic oxygen on Ag(110). The reactivities of sulfite and sulfate are strongly dependent on their surface structures, the c(6 × 2) sulfite showing the capacity to transfer oxygen to styrene.

Ceramic Composite Intermediate Temperature Stress-Rupture Properties Improved Significantly

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.; Hurst, Janet B.

2002-01-01

Silicon carbide (SiC) composites are considered to be potential materials for future aircraft engine parts such as combustor liners. It is envisioned that on the hot side (inner surface) of the combustor liner, composites will have to withstand temperatures in excess of 1200 C for thousands of hours in oxidizing environments. This is a severe condition; however, an equally severe, if not more detrimental, condition exists on the cold side (outer surface) of the combustor liner. Here, the temperatures are expected to be on the order of 800 to 1000 C under high tensile stress because of thermal gradients and attachment of the combustor liner to the engine frame (the hot side will be under compressive stress, a less severe stress-state for ceramics). Since these composites are not oxides, they oxidize. The worst form of oxidation for strength reduction occurs at these intermediate temperatures, where the boron nitride (BN) interphase oxidizes first, which causes the formation of a glass layer that strongly bonds the fibers to the matrix. When the fibers strongly bond to the matrix or to one another, the composite loses toughness and strength and becomes brittle. To increase the intermediate temperature stress-rupture properties, researchers must modify the BN interphase. With the support of the Ultra-Efficient Engine Technology (UEET) Program, significant improvements were made as state-of-the-art SiC/SiC composites were developed during the Enabling Propulsion Materials (EPM) program. Three approaches were found to improve the intermediate-temperature stress-rupture properties: fiber-spreading, high-temperature silicon- (Si) doped boron nitride (BN), and outside-debonding BN.

An investigation of the effect of surface impurities on the adsorption kinetics of hydrogen chemisorbed onto iron

NASA Technical Reports Server (NTRS)

Shanabarger, Mickey R.

1994-01-01

The goal of this program has been to develop an understanding of heterogeneous kinetic processes for those molecular species which produce gaseous hydrogen degradation of the mechanical properties of metallic structural materials. During the present program, the interaction of hydrogen with the surfaces of alpha-2 (Ti3Al) titanium aluminide, gamma (TiAl) titanium aluminide, and beryllium were studied. The interaction of low pressure hydrogen with gamma titanium aluminide and beryllium was found to be relatively weak. Weak in the sense that adsorption leads to a low surface concentration of dissociated hydrogen, i.e., the chemisorption process is reversible at room temperature (300 K) for gamma titanium aluminide and the sticking coefficient for chemisorption is extremely small for beryllium. Hydrogen was found to interact readily with alpha-2 titanium aluminide to form a stable surface hydride at 300 K. These results correlate well with other recent studies which show that the mechanical properties for alpha-2 titanium aluminide are readily degraded in hydrogen while gamma titanium aluminide exhibits less degradation and beryllium essentially no degradation. The interaction of oxygen with the surface of several of these materials was studied. More recently, preliminary hydrogen permeation studies were completed for three high temperature alloys, Incoloy 909, Mo-47.5Re (wt. %), and this past year, Haynes 188.

Hydrogen desorption from hydrogen fluoride and remote hydrogen plasma cleaned silicon carbide (0001) surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, Sean W., E-mail: sean.king@intel.com; Tanaka, Satoru; Davis, Robert F.

2015-09-15

Due to the extreme chemical inertness of silicon carbide (SiC), in-situ thermal desorption is commonly utilized as a means to remove surface contamination prior to initiating critical semiconductor processing steps such as epitaxy, gate dielectric formation, and contact metallization. In-situ thermal desorption and silicon sublimation has also recently become a popular method for epitaxial growth of mono and few layer graphene. Accordingly, numerous thermal desorption experiments of various processed silicon carbide surfaces have been performed, but have ignored the presence of hydrogen, which is ubiquitous throughout semiconductor processing. In this regard, the authors have performed a combined temperature programmed desorptionmore » (TPD) and x-ray photoelectron spectroscopy (XPS) investigation of the desorption of molecular hydrogen (H{sub 2}) and various other oxygen, carbon, and fluorine related species from ex-situ aqueous hydrogen fluoride (HF) and in-situ remote hydrogen plasma cleaned 6H-SiC (0001) surfaces. Using XPS, the authors observed that temperatures on the order of 700–1000 °C are needed to fully desorb C-H, C-O and Si-O species from these surfaces. However, using TPD, the authors observed H{sub 2} desorption at both lower temperatures (200–550 °C) as well as higher temperatures (>700 °C). The low temperature H{sub 2} desorption was deconvoluted into multiple desorption states that, based on similarities to H{sub 2} desorption from Si (111), were attributed to silicon mono, di, and trihydride surface species as well as hydrogen trapped by subsurface defects, steps, or dopants. The higher temperature H{sub 2} desorption was similarly attributed to H{sub 2} evolved from surface O-H groups at ∼750 °C as well as the liberation of H{sub 2} during Si-O desorption at temperatures >800 °C. These results indicate that while ex-situ aqueous HF processed 6H-SiC (0001) surfaces annealed at <700 °C remain terminated by some surface C–O and Si–O bonding, they may still exhibit significant chemical reactivity due to the creation of surface dangling bonds resulting from H{sub 2} desorption from previously undetected silicon hydride and surface hydroxide species.« less

Adsorption, polymerization and decomposition of acetaldehyde on clean and carbon-covered Rh(111) surfaces

NASA Astrophysics Data System (ADS)

Kovács, Imre; Farkas, Arnold Péter; Szitás, Ádám; Kónya, Zoltán; Kiss, János

2017-10-01

The adsorption and dissociation of acetaldehyde were investigated on clean and carbon-covered Rh(111) single crystal surfaces by electron energy loss spectroscopy (EELS), temperature programmed desorption (TPD), high-resolution electron energy loss spectroscopy (HREELS) and work function (Δφ) measurements. Acetaldehyde is a starting material for the catalytic production of many important chemicals and investigation of its reactions motivated by environmental purposes too. The adsorption of acetaldehyde on clean Rh(111) surface produced various types of adsorption forms. η1-(O)-CH3CHOa and η2-(O,C)-CH3CHOa are developing and characterized by HREELS. η1-CH3CHOa partly desorbed at Tp = 150 K, another part of these species are incorporated in trimer and linear 2D polimer species. The desorption of trimers (at amu 132) were observed in TPD with a peak maximum at Tp = 225 K. Above this temperature acetaldehyde either desorbed or bonded as a stable surface intermediate (η2-CH3CHOa) on the rhodium surface. The molecules decomposed to adsorbed products, and only hydrogen and carbon monoxide were analyzed in TPD. Surface carbon decreased the uptake of adsorbed acetaldehyde, inhibited the formation of polymers, nevertheless, it induced the Csbnd O bond scission and CO formation with 40-50 K lower temperature after higher acetaldehyde exposure.

Evaluation of Finite-Rate Gas/Surface Interaction Models for a Carbon Based Ablator

NASA Technical Reports Server (NTRS)

Chen, Yih-Kanq; Goekcen, Tahir

2015-01-01

Two sets of finite-rate gas-surface interaction model between air and the carbon surface are studied. The first set is an engineering model with one-way chemical reactions, and the second set is a more detailed model with two-way chemical reactions. These two proposed models intend to cover the carbon surface ablation conditions including the low temperature rate-controlled oxidation, the mid-temperature diffusion-controlled oxidation, and the high temperature sublimation. The prediction of carbon surface recession is achieved by coupling a material thermal response code and a Navier-Stokes flow code. The material thermal response code used in this study is the Two-dimensional Implicit Thermal-response and Ablation Program, which predicts charring material thermal response and shape change on hypersonic space vehicles. The flow code solves the reacting full Navier-Stokes equations using Data Parallel Line Relaxation method. Recession analyses of stagnation tests conducted in NASA Ames Research Center arc-jet facilities with heat fluxes ranging from 45 to 1100 wcm2 are performed and compared with data for model validation. The ablating material used in these arc-jet tests is Phenolic Impregnated Carbon Ablator. Additionally, computational predictions of surface recession and shape change are in good agreement with measurement for arc-jet conditions of Small Probe Reentry Investigation for Thermal Protection System Engineering.

Dissociative adsorption of CCl 4 on the Fe 3O 4(1 1 1)-(2×2) selvedge of α-Fe 2O 3(0 0 0 1)

NASA Astrophysics Data System (ADS)

Adib, K.; Mullins, D. R.; Totir, G.; Camillone, N.; Fitts, J. P.; Rim, K. T.; Flynn, G. W.; Osgood, R. M.

2003-02-01

The surface reactions of CCl 4 with the Fe 3O 4(1 1 1)-(2×2) selvedge of naturally occurring α-Fe 2O 3(0 0 0 1) single-crystals have been investigated using synchrotron X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD). CCl 4 was found to dissociate on the Fe 3O 4 surface at 100 K producing chemisorbed Cl and adsorbed CCl 2. TPD shows that the large majority of the dissociatively adsorbed CCl 2 fragments extract lattice oxygen and desorb as phosgene at >275 K. However, the XPS spectra show no evidence for the formation of surface-bound phosgene, at 100 K, indicating that its formation involves two steps. The first step, dissociation, is spontaneous at 100 K, whereas the second, oxygen atom abstraction to form phosgene, requires thermal excitation. Cl chemisorption yielded two separate species, the mono- and dichloride terminations of surface iron sites. The identification of these two surface terminations is based on the coverage dependence and the surface temperature history of their Cl 2p 3/2 peak intensity. For example, heating to >450 K allows the monochloride to transform into iron dichloride, indicating Cl adatom mobility at these temperatures.

Kinetic Model Development for the Combustion of Particulate Matter from Conventional and Soy Methyl Ester Diesel Fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strzelec, Andrea

2009-12-01

The primary objective of this research has been to investigate how the oxidation characteristics of diesel particulate matter (PM) are affected by blending soy-based biodiesel fuel with conventional ultra low sulfur diesel (ULSD) fuel. PM produced in a light duty engine from different biodiesel-conventional fuel blends was subjected to a range of physical and chemical measurements in order to better understand the mechanisms by which fuel-related changes to oxidation reactivity are brought about. These observations were then incorporated into a kinetic model to predict PM oxidation. Nanostructure of the fixed carbon was investigated by HR-TEM and showed that particulates frommore » biodiesel had a more open structure than particulates generated from conventional diesel fuel, which was confirmed by BET surface area measurements. Surface area evolution with extent of oxidation reaction was measured for PM from ULSD and biodiesel. Biodiesel particulate has a significantly larger surface area for the first 40% of conversion, at which point the samples become quite similar. Oxidation characteristics of nascent PM and the fixed carbon portion were measured by temperature programmed oxidation (TPO) and it was noted that increased biodiesel blending lowered the light-off temperature as well as the temperature where the peak rate of oxidation occurred. A shift in the oxidation profiles of all fuels was seen when the mobile carbon fraction was removed, leaving only the fixed carbon, however the trend in temperature advantage of the biofuel blending remained. The mobile carbon fraction was measured by temperature programmed desorption found to generally increase with increasing biodiesel blend level. The relative change in the light-off temperatures for the nascent and fixed carbon samples was found to be related to the fraction of mobile carbon. Effective Arrhenius parameters for fixed carbon oxidation were directly measured with isothermal, differential oxidation experiments. Normalizing the reaction rate to the total carbon surface area available for reaction allowed for the definition of a single reaction rate with constant activation energy (112.5 {+-} 5.8 kJ/mol) for the oxidation of PM, independent of its fuel source. A kinetic model incorporating the surface area dependence of fixed carbon oxidation rate and the impact of the mobile carbon fraction was constructed and validated against experimental data.« less

The Geostationary Operational Environmental Satellite (GOES) Product Generation System

NASA Technical Reports Server (NTRS)

Haines, S. L.; Suggs, R. J.; Jedlovec, G. J.

2004-01-01

The Geostationary Operational Environmental Satellite (GOES) Product Generation System (GPGS) is introduced and described. GPGS is a set of computer programs developed and maintained at the Global Hydrology and Climate Center and is designed to generate meteorological data products using visible and infrared measurements from the GOES-East Imager and Sounder instruments. The products that are produced by GPGS are skin temperature, total precipitable water, cloud top pressure, cloud albedo, surface albedo, and surface insolation. A robust cloud mask is also generated. The retrieval methodology for each product is described to include algorithm descriptions and required inputs and outputs for the programs. Validation is supplied where applicable.

Space Shuttle Orbiter flight heating rate measurement sensitivity to thermal protection system uncertainties

NASA Technical Reports Server (NTRS)

Bradley, P. F.; Throckmorton, D. A.

1981-01-01

A study was completed to determine the sensitivity of computed convective heating rates to uncertainties in the thermal protection system thermal model. Those parameters considered were: density, thermal conductivity, and specific heat of both the reusable surface insulation and its coating; coating thickness and emittance; and temperature measurement uncertainty. The assessment used a modified version of the computer program to calculate heating rates from temperature time histories. The original version of the program solves the direct one dimensional heating problem and this modified version of The program is set up to solve the inverse problem. The modified program was used in thermocouple data reduction for shuttle flight data. Both nominal thermal models and altered thermal models were used to determine the necessity for accurate knowledge of thermal protection system's material thermal properties. For many thermal properties, the sensitivity (inaccuracies created in the calculation of convective heating rate by an altered property) was very low.

(100) facets of γ-Al2O3: the active surfaces for alcohol dehydration reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwak, Ja Hun; Mei, Donghai; Peden, Charles HF

2011-05-01

Temperature programmed desorption (TPD) of ethanol, and methanol dehydration reaction were studied on γ-Al2O3 in order to identify the catalytic active sites for alcohol dehydration reactions. Two high temperature (> 473 K) desorption features were observed following ethanol adsorption. Samples calcined at T≤473 K displayed a desorption feature in the 523-533 K temperature range, while those calcined at T ≥ 673 K showed a single desorption feature at 498 K. The switch from the high to low temperature ethanol desorption correlated well with the dehydroxylation of the (100) facets of γ-Al2O3 that was predicted at 550 K DFT calculations. Theoreticalmore » DFT simulations of the mechanism of dehydration. on clean and hydroxylated γ-Al2O3(100) surfaces, find that a concerted elimination of ethylene from an ethanol molecule chemisorbed at an Al3+ pentacoordinated site is the rate limiting step for catalytic cycle on both surfaces. Furthermore, titration of the pentacoordinate Al3+ sites on the (100) facets of γ-Al2O3 by BaO completely turned off the methanol dehydration reaction activity. These results unambiguously demonstrate that only the (100) facets on γ-Al2O3 are the catalytic active surfaces for alcohol dehydration.« less

Multilevel measurements of surface temperature over undulating terrain planted to barley

NASA Technical Reports Server (NTRS)

Reginato, R. J. (Principal Investigator); Millard, J. P.; Hatfield, J. L.; Jackson, R. D.

1981-01-01

A ground and aircraft program was conducted to extend ground based methods for measuring soil moisture and crop water stress to aircraft and satellite altitudes. A 260ha agricultural field in California was used over the 1977-78 growing season. For cloud free days ground based temperature measurements over bare soil were related to soil moisture content. Water stress resulted from too much water, not from lack of it, as was expected. A theoretical examination of the canopy air temperature difference as affected by vapor pressure deficit and net radiation was developed. This analysis shows why surface temperatures delineate crop water stress under conditions of low humidity, but not under high humidity conditions. Multilevel temperatures acquired from the ground, low and high altitude aircraft, and the Heat Capacity Mapping Mission (HCMM) spacecraft were compared for two day and one night overpasses. The U-2 and low altitude temperatures were within 0.5 C. The HCMM data were analyzed using both the pre- and post-launch calibrations, with the former being considerably closer in agreement with the aircraft data than the latter.

Advanced Control Surface Seal Development for Future Space Vehicles

NASA Technical Reports Server (NTRS)

DeMange, J. J.; Dunlap, P. H., Jr.; Steinetz, B. M.

2004-01-01

NASA s Glenn Research Center (GRC) has been developing advanced high temperature structural seals since the late 1980's and is currently developing seals for future space vehicles as part of the Next Generation Launch Technology (NGLT) program. This includes control surface seals that seal the edges and hinge lines of movable flaps and elevons on future reentry vehicles. In these applications, the seals must operate at temperatures above 2000 F in an oxidizing environment, limit hot gas leakage to protect underlying structures, endure high temperature scrubbing against rough surfaces, and remain flexible and resilient enough to stay in contact with sealing surfaces for multiple heating and loading cycles. For this study, three seal designs were compared against the baseline spring tube seal through a series of compression tests at room temperature and 2000 F and flow tests at room temperature. In addition, canted coil springs were tested as preloaders behind the seals at room temperature to assess their potential for improving resiliency. Addition of these preloader elements resulted in significant increases in resiliency compared to the seals by themselves and surpassed the performance of the baseline seal at room temperature. Flow tests demonstrated that the seal candidates with engineered cores had lower leakage rates than the baseline spring tube design. However, when the seals were placed on the preloader elements, the flow rates were higher as the seals were not compressed as much and therefore were not able to fill the groove as well. High temperature tests were also conducted to asses the compatibility of seal fabrics against ceramic matrix composite (CMC) panels anticipated for use in next generation launch vehicles. These evaluations demonstrated potential bonding issues between the Nextel fabrics and CMC candidates.

Performance Technology Program (PTP-S 2). Volume 9: Evaluation of reentry vehicle nosetip transition and heat transfer in the AEDC hyperballistics track G

NASA Astrophysics Data System (ADS)

Wassel, A. T.; Shih, W. C. L.; Curtis, R. J.

1981-01-01

Boundary layer transition and surface heating distributions on graphite fine weave carbon-carbon, and metallic nosetip materials were derived from surface temperature responses measured in nitrogen environments during both free-flight and track-guided testing in the AEDC Hyperballistics Range/Track G. Innovative test procedures were developed, and heat transfer results were validated against established theory through experiments using a super-smooth tungsten model. Quantitative definitions of mean transition front locations were established by deriving heat flux distributions from measured temperatures, and comparisons made with existing nosetip transition correlations. Qualitative transition locations were inferred directly from temperature distributions to investigate preferred orientations on fine weave nosetips. Levels of roughness augmented heat transfer were generally shown to be below values predicted by state of the art methods.

Two-phase working fluids for the temperature range of 50 to 350 deg, phase 2

NASA Technical Reports Server (NTRS)

Saaski, E. W.; Hartl, J. H.

1980-01-01

Several two phase heat transfer fluids were tested in aluminum and carbon steel reflux capsules for over 25,000 hours at temperatures up to 300 C. Several fluids showed very good stability and would be useful for long duration heat transfer applications over the range 100 to 350 C. Instrumentation for the measurement of surface tension and viscosity were constructed for use with heat transfer fluids over the temperature range 0 to 300 C and with pressures from 0 to 10 atmospheres. The surface tension measuring device constructed requires less than a 1.0 cc sample and displays an accuracy of about 5 percent in preliminary tests, while the viscometer constructed for this program requires a 0.05 cc sample and shows an accuracy of about 5 percent in initial tests.

Cyclic arc plasma tests of RSI materials using a preheater

NASA Technical Reports Server (NTRS)

Stewart, D. A.

1973-01-01

The results of a test program are reported in which a preheater was used with an arc plasma stream to study the thermal response of samples of candidate reusable surface insulation materials for the space shuttle. The preheater simulated the shuttle temperature history during the first and last portions of the test cycle, which could not be simulated by the air arc plasma flow. Pre- and post-test data taken for each of the materials included magnified views, optical properties, and chemical analyses. The test results indicate that the mullite base samples experience higher surface temperatures than the other materials at heating rates greater than 225 kw/sq m. The ceramic fibrous mullite and silica coatings show noncatalytic wall behavior. Internal temperature response data for the materials are compared and correlated with analytical predictions.

Electronic Components and Systems for Cryogenic Space Applications

NASA Technical Reports Server (NTRS)

Patterson, R. L.; Hammoud, A.; Dickman, J. E.; Gerber, S.; Elbuluk, M. E.; Overton, E.

2001-01-01

Electronic components and systems capable of operation at cryogenic temperatures are anticipated in many future NASA space missions such as deep space probes and planetary surface exploration. For example, an unheated interplanetary probe launched to explore the rings of Saturn would reach an average temperature near Saturn of about - 183 C. In addition to surviving the deep space harsh environment, electronics capable of low temperature operation would contribute to improving circuit performance, increasing system efficiency, and reducing payload development and launch costs. Terrestrial applications where components and systems must operate in low temperature environments include cryogenic instrumentation, superconducting magnetic energy storage, magnetic levitation transportation system, and arctic exploration. An on-going research and development program at the NASA Glenn Research Center focuses on the development of reliable electronic devices and efficient power systems capable of surviving in low temperature environments. An overview of the program will be presented in this paper. A description of the low temperature test facilities along with selected data obtained from in-house component testing will also be discussed. Ongoing research activities that are being performed in collaboration with various organizations will also be presented.

Global ocean monitoring for the World Climate Research Programme.

PubMed

Revelle, R; Bretherton, F

1986-07-01

Oceanic research and modelling for the World Climate Research Program will utilize several recently-developed instruments and measuring techniques as well as well-tested, long-used instruments. Ocean-scanning satellites will map the component of the ocean-surface topography related to ocean currents and mesoscale eddies and to fluctuating water volumes caused by ocean warming and cooling. Other satellite instruments will measure the direction and magnitude of wind stress on the sea surface, surface water temperatures, the distribution of chlorophyll and other photosynthetic pigments, the characteristics of internal waves, and possible precipitation over the ocean. Networks of acoustic transponders will obtain a three-dimensional picture of the distribution of temperature from the surface down to mid-depth and of long-term changes in temperature at depth. Ocean research vessels will determine the distribution and fate of geochemical tracers and will also make high-precision, deep hydrographic casts. Ships of opportunity, using expendable instruments, will measure temperature, salinity and currents in the upper water layers. Drifting and anchored buoys will also measure these properties as well as those of the air above the sea surface. Tide gauges installed on islands and exposed coastal locations will measure variations in monthly and shorter-period mean sea level. These tide gauges will provide 'ground truth' for the satellite maps of sea-surface topography, and will also determine variations in ocean currents and temperature.All these instruments will be used in several major programs, the most ambitious of which is the World Ocean Circulation Experiment (WOCE) designed to obtain global measurements of major currents throughout the world ocean, greater understanding of the transformation of water masses, and the role of advective, convective, and turbulent processes in exchange of properties between surface and deep-ocean layers.A five- to ten-year experiment-"Tropical Oceans and Global Atmosphere (TOGA)"-will be undertaken to sudy the sequence of events of air-sea interactions in the tropical oceans and their impact on climatic variations on land-for example, variations in the strength and location of the Indian Ocean monsoon, droughts in low latitudes, and climatic fluctuations in temperate latitudes.Experimental and continuing time series will be taken at fixed locations to obtain a better picture of the magnitude and causes of ocean climate variability. National and multinational systematic repeated measurements along selected ocean transects or in specific ocean areas will be taken to determine oceanic variability and teleconnections between oceanic and atmospheric processes. Examples are the long Japanese section along the meridian of 137° E and the 'Sections' program of the USSR and several other countries in Energy-Active zones.The results from this wide range of observations and experiments will be used to guide and define mathematical models of the ocean circulation and its interactions with the atmosphere.It can be shown that biogeochemical processes in the ocean play an important role in determining the carbon dioxide content of the atmosphere and thus in causing long-term climatic changes. Variations in the biological productivity of sub-surface waters cause variations in the effectveness of the biological pump which carries organic carbon down into deeper waters where it is oxidized. Studies of ice cores from 20 000 to 30 000 yr before the present indicate that atmospheric carbon dioxide varied by a factor of 2 within times of the order of 100 yr, and these variations were accompanied by large excursions in atmospheric temperature. Thus, ocean climatic monitoring must take into account measurements of both biological and physical variations in the ocean.

Radiative, actively cooled panel tests results

NASA Technical Reports Server (NTRS)

Shore, C. P.; Nowak, R. J.; Sharpe, E. L.

1978-01-01

The radiative, actively cooled panel designed to withstand a uniform incident heat flux of 136 kW/sq m to a 444 K surface temperature was evaluated. The test program consisted of preliminary static thermal mechanical loading and aerothermal flow tests. Test results are briefly discussed.

Development of sensors for ceramic components in advanced propulsion systems

NASA Technical Reports Server (NTRS)

Atkinson, William H.; Cyr, M. A.; Strange, R. R.

1994-01-01

The 'Development of Sensors for Ceramics Components in Advanced Propulsion Systems' program was divided into two phases. The objectives of Phase 1 were to analyze, evaluate and recommend sensor concepts for the measurement of surface temperature, strain and heat flux on ceramic components for advanced propulsion systems. The results of this effort were previously published in NASA CR-182111. As a result of Phase 1, three approaches were recommended for further development: pyrometry, thin-film sensors, and thermographic phosphors. The objectives of Phase 2 were to fabricate and conduct laboratory demonstration tests of these systems. A summary report of the Phase 2 effort, together with conclusions and recommendations for each of the categories evaluated, has been submitted to NASA. Emittance tests were performed on six materials furnished by NASA Lewis Research Center. Measurements were made of various surfaces at high temperature using a Thermogage emissometer. This report describes the emittance test program and presents a summary of the results.

Arctic (and Antarctic) Observing Experiment - an Assessment of Methods to Measure Temperature over Polar Environments

NASA Astrophysics Data System (ADS)

Rigor, I. G.; Clemente-Colon, P.; Nghiem, S. V.; Hall, D. K.; Woods, J. E.; Henderson, G. R.; Zook, J.; Marshall, C.; Gallage, C.

2014-12-01

The Arctic environment has been undergoing profound changes; the most visible is the dramatic decrease in Arctic sea ice extent (SIE). These changes pose a challenge to our ability to measure surface temperature across the Polar Regions. Traditionally, the International Arctic Buoy Programme (IABP) and International Programme for Antarctic Buoys (IPAB) have measured surface air temperature (SAT) at 2-m height, which minimizes the ambiguity of measurements near of the surface. Specifically, is the temperature sensor measuring open water, snow, sea ice, or air? But now, with the dramatic decrease in Arctic SIE, increase in open water during summer, and the frailty of the younger sea ice pack, the IABP has had to deploy and develop new instruments to measure temperature. These instruments include Surface Velocity Program (SVP) buoys, which are commonly deployed on the world's ice-free oceans and typically measure sea surface temperature (SST), and the new robust Airborne eXpendable Ice Beacons (AXIB), which measure both SST and SAT. "Best Practice" requires that these instruments are inter-compared, and early results showing differences in collocated temperature measurements of over 2°C prompted the establishment of the IABP Arctic Observing Experiment (AOX) buoy test site at the US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) site in Barrow, Alaska. Preliminary results showed that the color of the hull of SVP buoys introduces a bias due to solar heating of the buoy. Since then, we have recommended that buoys should be painted white to reduce biases in temperature measurements due to different colors of the buoys deployed in different regions of the Arctic or the Antarctic. Measurements of SAT are more robust, but some of the temperature shields are susceptible to frosting. During our presentation we will provide an intercomparison of the temperature measurements at the AOX test site (i.e. high quality DOE/ARM observations compared with unattended buoy measurements, and satellite retrievals). We will also show how these data may be used to improve our record of temperature over polar environments.

Advanced high temperature static strain sensor development

NASA Technical Reports Server (NTRS)

Hulse, C. O.; Stetson, K. A.; Grant, H. P.; Jameikis, S. M.; Morey, W. W.; Raymondo, P.; Grudkowski, T. W.; Bailey, R. S.

1986-01-01

An examination was made into various techniques to be used to measure static strain in gas turbine liners at temperatures up to 1150 K (1600 F). The methods evaluated included thin film and wire resistive devices, optical fibers, surface acoustic waves, the laser speckle technique with a heterodyne readout, optical surface image and reflective approaches and capacitive devices. A preliminary experimental program to develop a thin film capacitive device was dropped because calculations showed that it would be too sensitive to thermal gradients. In a final evaluation program, the laser speckle technique appeared to work well up to 1150 K when it was used through a relatively stagnant air path. The surface guided acoustic wave approach appeared to be interesting but to require too much development effort for the funds available. Efforts to develop a FeCrAl resistive strain gage system were only partially successful and this part of the effort was finally reduced to a characterization study of the properties of the 25 micron diameter FeCrAl (Kanthal A-1) wire. It was concluded that this particular alloy was not suitable for use as the resistive element in a strain gage above about 1000 K.

Advanced high temperature static strain sensor development

NASA Astrophysics Data System (ADS)

Hulse, C. O.; Stetson, K. A.; Grant, H. P.; Jameikis, S. M.; Morey, W. W.; Raymondo, P.; Grudkowski, T. W.; Bailey, R. S.

1986-08-01

An examination was made into various techniques to be used to measure static strain in gas turbine liners at temperatures up to 1150 K (1600 F). The methods evaluated included thin film and wire resistive devices, optical fibers, surface acoustic waves, the laser speckle technique with a heterodyne readout, optical surface image and reflective approaches and capacitive devices. A preliminary experimental program to develop a thin film capacitive device was dropped because calculations showed that it would be too sensitive to thermal gradients. In a final evaluation program, the laser speckle technique appeared to work well up to 1150 K when it was used through a relatively stagnant air path. The surface guided acoustic wave approach appeared to be interesting but to require too much development effort for the funds available. Efforts to develop a FeCrAl resistive strain gage system were only partially successful and this part of the effort was finally reduced to a characterization study of the properties of the 25 micron diameter FeCrAl (Kanthal A-1) wire. It was concluded that this particular alloy was not suitable for use as the resistive element in a strain gage above about 1000 K.

Numerical analysis of one-dimensional temperature data for groundwater/surface-water exchange with 1DTempPro

NASA Astrophysics Data System (ADS)

Voytek, E. B.; Drenkelfuss, A.; Day-Lewis, F. D.; Healy, R. W.; Lane, J. W.; Werkema, D. D.

2012-12-01

Temperature is a naturally occurring tracer, which can be exploited to infer the movement of water through the vadose and saturated zones, as well as the exchange of water between aquifers and surface-water bodies, such as estuaries, lakes, and streams. One-dimensional (1D) vertical temperature profiles commonly show thermal amplitude attenuation and increasing phase lag of diurnal or seasonal temperature variations with propagation into the subsurface. This behavior is described by the heat-transport equation (i.e., the convection-conduction-dispersion equation), which can be solved analytically in 1D under certain simplifying assumptions (e.g., sinusoidal or steady-state boundary conditions and homogeneous hydraulic and thermal properties). Analysis of 1D temperature profiles using analytical models provides estimates of vertical groundwater/surface-water exchange. The utility of these estimates can be diminished when the model assumptions are violated, as is common in field applications. Alternatively, analysis of 1D temperature profiles using numerical models allows for consideration of more complex and realistic boundary conditions. However, such analyses commonly require model calibration and the development of input files for finite-difference or finite-element codes. To address the calibration and input file requirements, a new computer program, 1DTempPro, is presented that facilitates numerical analysis of vertical 1D temperature profiles. 1DTempPro is a graphical user interface (GUI) to the USGS code VS2DH, which numerically solves the flow- and heat-transport equations. Pre- and post-processor features within 1DTempPro allow the user to calibrate VS2DH models to estimate groundwater/surface-water exchange and hydraulic conductivity in cases where hydraulic head is known. This approach improves groundwater/ surface-water exchange-rate estimates for real-world data with complexities ill-suited for examination with analytical methods. Additionally, the code allows for time-varying temperature and hydraulic boundary conditions. Here, we present the approach and include examples for several datasets from stream/aquifer systems.

Studies of the kinetics and mechanisms of perfluoroether reactions on iron and oxidized iron surfaces

NASA Technical Reports Server (NTRS)

Napier, Mary E.; Stair, Peter C.

1992-01-01

Polymeric perfluoroalkylethers are being considered for use as lubricants in high temperature applications, but have been observed to catalytically decompose in the presence of metals. X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) were used to explore the decomposition of three model fluorinated ethers on clean polycrystalline iron surfaces and iron surfaces chemically modified with oxygen. Low temperature adsorption of the model fluorinated ethers on the clean, oxygen modified and oxidized iron surfaces was molecular. Thermally activated defluorination of the three model compounds was observed on the clean iron surface at remarkably low temperatures, 155 K and below, with formation of iron fluoride. Preferential C-F bond scission occurred at the terminal fluoromethoxy, CF3O, of perfluoro-1-methoxy-2-ethoxy ethane and perfluoro-1-methoxy-2-ethoxy propane and at CF3/CF2O of perfluoro-1,3-diethoxy propane. The reactivity of the clean iron toward perfluoroalkylether decomposition when compared to other metals is due to the strength of the iron fluoride bond and the strong electron donating ability of the metallic iron. Chemisorption of an oxygen overlayer lowered the reactivity of the iron surface to the adsorption and decomposition of the three model fluorinated ethers by blocking active sites on the metal surface. Incomplete coverage of the iron surface with chemisorbed oxygen results in a reaction which resembles the defluorination reaction observed on the clean iron surface. Perfluoro-1-methoxy-2-ethoxy ethane reacts on the oxidized iron surface at 138 K, through a Lewis acid assisted cleavage of the carbon oxygen bond, with preferential attack at the terminal fluoromethoxy, CF3O. The oxidized iron surface did not passivate, but became more reactive with time. Perfluoro-1-methoxy-2-ethoxy propane and perfluoro-1,3-diethoxy propane desorbed prior to the observation of decomposition on the oxidized iron surface.

An overview of the NSCAT/N-ROSS program

NASA Technical Reports Server (NTRS)

Martin, B. D.; Freilich, Michael H.; Li, F. K.; Callahan, Phillip S.

1986-01-01

The NASA Scatterometer (NSCAT) to fly on the U.S. Navy Remote Ocean Sensing System (N-ROSS) mission is presented. The overall N-ROSS mission, the NSCAT flight instrument and groundbased data processing/distribution system, and NASA-supported science and verification activities are described. The N-ROSS system is designed to provide measurements of near-surface wind, ocean topography, wave height, sea-surface temperature, and atmospheric water content over the global oceans. The NSCAT is an improved version of the Seasat scatterometer. It will measure near surface vector winds.

Water Quality Research Program: Abstracts of the International Symposium on Gas Transfer at Water Surfaces (2nd) Held in Minneapolis, Minnesota on 11-14 September 1990

DTIC Science & Technology

1990-08-01

layer on the surface) it is 2 - 3 times less. Many in- situ observations show that different patterns of temperature distribution in the surface water...Coeficiente de Reaeracao dos Escoamentos Naturais da Agua com o Emprego de Tracador Gasoso. M.Sc Dissertation, Universidade de Sao Paulo, EESC, Depto. de...structure. If methane is present in measurable quantities it may prove to be an excellent in- situ tracer of gas transfer. Transfer efficiency has been used

Structure and Spectroscopy of Buried Interfaces in Organic Thin Films and Colloids

DTIC Science & Technology

2012-03-01

A systematic study of adsorption of linear acenes, from benzene to pentacene , on metal surfaces has been conducted using Temperature Programmed...inter- adsorbate repulsive interaction resulted from local dipole moment at the adsorption site induced by the adsorbate-surface charge transfer...adsorbate interactions resulting from a local dipole moment of 4.3 D at the adsorbate-substrate complex. The interface dipole of naphthalene on Ag is 51

Photodecomposition of Mo(CO)/sub 6/ adsorbed on Si(100)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Creighton, J.R.

1985-01-01

The photochemical decomposition of Mo(CO)/sub 6/ layers physisorbed on Si(100) was investigated to determine the feasibility of molybdenum deposition and also to examine the photochemical reaction mechanism and efficiency. Temperature programmed desorption (TPD) was used to investigate the interaction of Mo(CO)/sub 6/ with the silicon surface before and after irradiation. Auger spectroscopy was used to determine surface elemental composition before Mo(CO)/sub 6/ adsorption and after photodecomposition.

An Investigation of Turbulent Heat Exchange in the Subtropics

DTIC Science & Technology

2014-09-30

meteorological sensors aboard the research vessel the R/V Revelle during the DYNAMO field program. In situ meteorology and high-rate flux sensors operated...continuously while in the sampling period for DYNAMO Leg 3. This included all sensors operating during Leg 2 with the addition of a closed-path LI...stress; wave data; surface and near surface sea temperatures, salinity and currents; and other key variables specifically requested by DYNAMO /LASP PIs

Collisional quenching of atoms and molecules on spacecraft thermal protection surfaces

NASA Technical Reports Server (NTRS)

Marinelli, W. J.; Green, B. D.

1988-01-01

Preliminary results of a research program to determine energy partitioning in spacecraft thermal protection materials due to atom recombination at the gas-surface interface are presented. The primary focus of the research is to understand the catalytic processes which determine heat loading on Shuttle, Aeroassisted OTV, and NASP thermal protection surfaces in nonequilibrium flight regimes. Highly sensitive laser diagnostics based on laser-induced fluorescence and resonantly-enhanced multiphoton ionization spectroscopy are used to detect atoms and metastable molecules. At low temperatures, a discharge flow reactor is employed to measure deactivation/recombination coefficients for O-atoms, N-atoms, and O2. Detection methods are presented for measuring O-atoms, O2 and N2, and results for deactivation of O2 and O-atoms on reaction-cured glass and Ni surfaces. Both atom recombination and metastable product formation are examined. Radio-frequency discharges are used to produce highly dissociated beams of atomic species at energies characteristic of the surface temperature. Auger electron spectroscopy is employed as a diagnostic of surface composition in order to accurately define and control measurement conditions.

Development of design allowables data for adhesives for attaching reusables surface insulation, addendum 1A

NASA Technical Reports Server (NTRS)

Owen, H. P.; Carroll, M. T.

1973-01-01

The task consisted of conducting mechanical and thermal tests to establish design allowables data on a new room temperature vulcanizing (RTV) silicone adhesive, X3-6004. Low modulus, coupled with relatively low density and good low-temperature properties of this adhesive, places it in contention as a candidate for attaching reusable surface insulation on the space shuttle. Data obtained show that the modulus values of X3-6004 are significantly lower than those of RTV-560 and the other three adhesives characterized at test temperatures from 550 to -175 F. At -175, -200 and -270 F, the modulus of X3-6004 is approximately the same as GE RTV-560 and the other three silicone adhesives. The X3-6004 adhesive exhibits good processing properties. It has a 12 percent lower density than RTV-560. Although lower in overall strength properties as compared to the other adhesives in the program, X3-6004 has adequate adhesion to 2024T81 aluminum to compete as an adhesive for attaching reusable surface insulation. It does exhibit some tendency to revert and soften at temperatures above 350 F when in a confined area.

Reentry heat transfer analysis of the space shuttle orbiter

NASA Technical Reports Server (NTRS)

Ko, W. L.; Quinn, R. D.; Gong, L.

1982-01-01

A structural performance and resizing finite element thermal analysis computer program was used in the reentry heat transfer analysis of the space shuttle. Two typical wing cross sections and a midfuselage cross section were selected for the analysis. The surface heat inputs to the thermal models were obtained from aerodynamic heating analyses, which assumed a purely turbulent boundary layer, a purely laminar boundary layer, separated flow, and transition from laminar to turbulent flow. The effect of internal radiation was found to be quite significant. With the effect of the internal radiation considered, the wing lower skin temperature became about 39 C (70 F) lower. The results were compared with fight data for space transportation system, trajectory 1. The calculated and measured temperatures compared well for the wing if laminar flow was assumed for the lower surface and bay one upper surface and if separated flow was assumed for the upper surfaces of bays other than bay one. For the fuselage, good agreement between the calculated and measured data was obtained if laminar flow was assumed for the bottom surface. The structural temperatures were found to reach their peak values shortly before touchdown. In addition, the finite element solutions were compared with those obtained from the conventional finite difference solutions.

Why Do Elephants Flap Their Ears?

NASA Astrophysics Data System (ADS)

Koffi, Moise; Jiji, Latif; Andreopoulos, Yiannis

2009-11-01

It is estimated that a 4200 kg elephant generates as much as 5.12 kW of heat. How the elephant dissipates its metabolic heat and regulates its body temperature has been investigated during the past seven decades. Findings and conclusions differ sharply. The high rate of metabolic heat coupled with low surface area to volume ratio and the absence of sweat glands eliminate surface convection as the primary mechanism for heat removal. Noting that the elephant ears have high surface area to volume ratio and an extensive vascular network, ear flapping is thought to be the principal thermoregulatory mechanism. A computational and experimental program is carried out to examine flow and heat transfer characteristics. The ear is modeled as a uniformly heated oscillating rectangular plate. Our computational work involves a three-dimensional time dependent CFD code with heat transfer capabilities to obtain predictions of the flow field and surface temperature distributions. This information was used to design an experimental setup with a uniformly heated plate of size 0.2m x 0.3m oscillating at 1.6 cycles per second. Results show that surface temperature increases and reaches a steady periodic oscillation after a period of transient oscillation. The role of the vortices shed off the plate in heat transfer enhancement will be discussed.

Seasat-A and the commercial ocean community

NASA Technical Reports Server (NTRS)

Montgomery, D. R.; Wolff, P.

1977-01-01

The Seasat-A program has been initiated as a 'proof-of-concept' mission to evaluate the effectiveness of remotely sensing oceanology and related meteorological phenomena from a satellite platform in space utilizing sensors developed on previous space and aircraft test programs. The sensors include three active microwave sensors; a radar altimeter, a windfield scatterometer, and a synthetic aperture radar. A passive scanning multifrequency microwave radiometer, visual and infrared radiometer are also included. All weather, day-night measurements of sea surface temperature, surface wind speed/direction and sea state and directional wave spectra will be made. Two key programs are planned for data utilization with users during the mission. Foremost is a program with the commercial ocean community to test the utility of Seasat-A data and to begin the transfer of ocean remote sensing technology to the civil sector. A second program is a solicitation of investigations, led by NOAA, to involve the ocean science community in a series of scientific investigations.

COSIM: A Finite-Difference Computer Model to Predict Ternary Concentration Profiles Associated with Oxidation and Interdiffusion of Overlay-Coated Substrates

NASA Technical Reports Server (NTRS)

Nesbitt, James A.

2000-01-01

A finite-difference computer program (COSIM) has been written which models the one-dimensional, diffusional transport associated with high-temperature oxidation and interdiffusion of overlay-coated substrates. The program predicts concentration profiles for up to three elements in the coating and substrate after various oxidation exposures. Surface recession due to solute loss is also predicted. Ternary cross terms and concentration-dependent diffusion coefficients are taken into account. The program also incorporates a previously-developed oxide growth and spalling model to simulate either isothermal or cyclic oxidation exposures. In addition to predicting concentration profiles after various oxidation exposures, the program can also be used to predict coating fife based on a concentration dependent failure criterion (e.g., surface solute content drops to two percent). The computer code, written in an extension of FORTRAN 77, employs numerous subroutines to make the program flexible and easily modifiable to other coating oxidation problems.

Adsorption and Desorption of Hydrogen by Gas-Phase Palladium Clusters Revealed by In Situ Thermal Desorption Spectroscopy.

PubMed

Takenouchi, Masato; Kudoh, Satoshi; Miyajima, Ken; Mafuné, Fumitaka

2015-07-02

Adsorption and desorption of hydrogen by gas-phase Pd clusters, Pdn(+), were investigated by thermal desorption spectroscopy (TDS) experiments and density functional theory (DFT) calculations. The desorption processes were examined by heating the clusters that had adsorbed hydrogen at room temperature. The clusters remaining after heating were monitored by mass spectrometry as a function of temperature up to 1000 K, and the temperature-programmed desorption (TPD) curve was obtained for each Pdn(+). It was found that hydrogen molecules were released from the clusters into the gas phase with increasing temperature until bare Pdn(+) was formed. The threshold energy for desorption, estimated from the TPD curve, was compared to the desorption energy calculated by using DFT, indicating that smaller Pdn(+) clusters (n ≤ 6) tended to have weakly adsorbed hydrogen molecules, whereas larger Pdn(+) clusters (n ≥ 7) had dissociatively adsorbed hydrogen atoms on the surface. Highly likely, the nonmetallic nature of the small Pd clusters prevents hydrogen molecule from adsorbing dissociatively on the surface.

Ro-vibrational averaging of the isotropic hyperfine coupling constant for the methyl radical

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adam, Ahmad Y.; Jensen, Per, E-mail: jensen@uni-wuppertal.de; Yachmenev, Andrey

2015-12-28

We present the first variational calculation of the isotropic hyperfine coupling constant of the carbon-13 atom in the CH{sub 3} radical for temperatures T = 0, 96, and 300 K. It is based on a newly calculated high level ab initio potential energy surface and hyperfine coupling constant surface of CH{sub 3} in the ground electronic state. The ro-vibrational energy levels, expectation values for the coupling constant, and its temperature dependence were calculated variationally by using the methods implemented in the computer program TROVE. Vibrational energies and vibrational and temperature effects for coupling constant are found to be in verymore » good agreement with the available experimental data. We found, in agreement with previous studies, that the vibrational effects constitute about 44% of the constant’s equilibrium value, originating mainly from the large amplitude out-of-plane bending motion and that the temperature effects play a minor role.« less

Electronics for Low Temperature Space Exploration Missions

NASA Technical Reports Server (NTRS)

Patterson, Richard L.; Hammoud, Ahmad; Elbuluk, Malik

2007-01-01

Exploration missions to outer planets and deep space require spacecraft, probes, and on-board data and communication systems to operate reliably and efficiently under severe harsh conditions. On-board electronics, in particular those in direct exposures to the space environment without any shielding or protection, will encounter extreme low temperature and thermal cycling in their service cycle in most of NASA s upcoming exploration missions. For example, Venus atmosphere, Jupiter atmosphere, Moon surface, Pluto orbiter, Mars, comets, Titan, Europa, and James Webb Space Telescope all involve low-temperature surroundings. Therefore, electronics for space exploration missions need to be designed for operation under such environmental conditions. There are ongoing efforts at the NASA Glenn Research Center (GRC) to establish a database on the operation and reliability of electronic devices and circuits under extreme temperature operation for space applications. This work is being performed under the Extreme Temperature Electronics Program with collaboration and support of the NASA Electronic Parts and Packaging (NEPP) Program. The results of these investigations will be used to establish safe operating areas and to identify degradation and failure modes, and the information will be disseminated to mission planners and system designers for use as tools for proper part selection and in risk mitigation. An overview of this program along with experimental data will be presented.

Methylene migration and coupling on a non-reducible metal oxide: The reaction of dichloromethane on stoichiometric α-Cr 2O 3(0001)

DOE PAGES

Dong, Yujung; Brooks, John D.; Chen, Tsung-Liang; ...

2014-09-17

The reaction of CH 2Cl 2 over the nearly-stoichiometric α-Cr 2O 3(0001) surface produces gas phase ethylene, methane and surface chlorine adatoms. The reaction is initiated by the decomposition of CH 2Cl 2 into surface methylene and chlorine. Photoemission indicates that surface cations are the preferred binding sites for both methylene and chlorine adatoms. Two reaction channels are observed for methylene coupling to ethylene in temperature-programmed desorption (TPD). A desorption-limited, low-temperature route is attributed to two methylenes bound at a single site. The majority of ethylene is produced by a reaction-limited process involving surface migration (diffusion) of methylene as themore » rate-limiting step. DFT calculations indicate the surface diffusion mechanism is mediated by surface oxygen anions. The source of hydrogen for methane formation is adsorbed background water. Chlorine adatoms produced by the dissociation of CH 2Cl 2 deactivate the surface by simple site-blocking of surface Cr 3+ sites. Finally, a comparison of experiment and theory shows that DFT provides a better description of the surface chemistry of the carbene intermediate than DFT+U using reported parameters for a best representation of the bulk electronic properties of α-Cr 2O 3.« less

The READY program: Building a global potential energy surface and reactive dynamic simulations for the hydrogen combustion.

PubMed

Mogo, César; Brandão, João

2014-06-30

READY (REActive DYnamics) is a program for studying reactive dynamic systems using a global potential energy surface (PES) built from previously existing PESs corresponding to each of the most important elementary reactions present in the system. We present an application to the combustion dynamics of a mixture of hydrogen and oxygen using accurate PESs for all the systems involving up to four oxygen and hydrogen atoms. Results at the temperature of 4000 K and pressure of 2 atm are presented and compared with model based on rate constants. Drawbacks and advantages of this approach are discussed and future directions of research are pointed out. Copyright © 2014 Wiley Periodicals, Inc.

Thermodynamic and related properties of parahydrogen from the triple point to 300 K at pressures to 1000 bar

NASA Technical Reports Server (NTRS)

Weber, L. A.

1975-01-01

Compressibility measurements and thermodynamic properties data for parahydrogen were extended to higher temperatures and pressures. Results of an experimental program are presented in the form of new pressure, volume and temperature data in the temperature range 23 to 300 K at pressures up to 800 bar. Also given are tables of thermodynamic properties on isobars to 1000 bar including density, internal energy, enthalpy, entropy, specific heats at constant volume and constant pressure, velocity of sound, and surface derivatives. The accuracy of the data is discussed and comparisons are made with previous data.

High field 27Al MAS NMR and TPD studies of active sites in ethanol dehydration using thermally treated transitional aluminas as catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Jian Zhi; Xu, Suochang; Kwak, Ja Hun

High field quantitative 27Al MAS NMR and temperature programmed desorption (TPD) of ethanol are used to study the surface and phase transformation of gamma-Al2O3 during calcination in the temperature range of 500 to 1300 degrees C. Following ethanol adsorption, ethylene is generated during TPD with a desorption temperature > 200 degrees C. With increasing calcination temperature prior to TPD, the amount of ethylene produced decreases monotonically. Significantly, 27Al MAS NMR reveals that the amount of penta-coordinate Al3+ ions (Lewis acid sites) also decreases with increasing calcination temperature. In fact, a strong correlation between the amount of penta-coordinate Al3+ ions andmore » the amount of strongly adsorbed ethanol molecules (i.e., the ones that convert to ethylene during TPD) is obtained. This result indicates that the penta-coordinate aluminum sites are the catalytic active sites on alumina surfaces during ethanol dehydration reaction across the entire course of gamma- to alpha-Al2O3 phase transformations.« less

Hierarchically porous LaFeO3 perovskite prepared from the pomelo peel bio-template for catalytic oxidation of NO

NASA Astrophysics Data System (ADS)

Zhao, Shaojun; Wang, Li; Wang, Ying; Li, Xing

2018-05-01

In this paper, pomelo peel was used as biological template to obtain hierarchically porous LaFeO3 perovskite for the catalytic oxidation of NO to NO2. In addition, X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption-desorption analyses, X-ray photoelectron spectra (XPS), NO temperature-programmed desorption (NO-TPD), oxygen temperature-programmed desorption (O2-TPD) and hydrogen temperature-programmed reduction (H2-TPR) were used to investigate the micro-structure and the redox properties of the hierarchically porous LaFeO3 perovskite prepared from pomelo peel biological template and the LaFeO3 perovskite without the biological template. The results indicated that the hierarchically porous LaFeO3 perovskite successfully replicated the porous structure of pomelo peel with high specific surface area. Compared to the LaFeO3 perovskite prepared without the pomelo peel template, the hierarchically porous LaFeO3 perovskite showed better catalytic oxidization of NO to NO2 under the same conditions. The maximum NO conversions for LaFeO3 prepared with and without template were 90% at 305 °C and 76% at 313 °C, respectively. This is mainly attributed to the higher ratio of Fe4+/Fe3+, the hierarchically porous structure with more adsorbed oxygen species and higher surface area for the hierarchically porous LaFeO3 perovskite compared with the sample prepared without the pomelo peel template.

Evaluation of two transport aircraft and several ground test vehicle friction measurements obtained for various runway surface types and conditions. A summary of test results from joint FAA/NASA Runway Friction Program

NASA Technical Reports Server (NTRS)

Yager, Thomas J.; Vogler, William A.; Baldasare, Paul

1990-01-01

Tests with specially instrumented NASA Boeing 737 and 727 aircraft together with several different ground friction measuring devices were conducted for a variety of runway surface types and conditions. These tests are part of joint FAA/NASA Aircraft/Ground Vehicle Runway Friction Program aimed at obtaining a better understanding of aircraft ground handling performance under adverse weather conditions and defining relationships between aircraft and ground vehicle tire friction measurements. Aircraft braking performance on dry, wet, snow and ice-covered runway conditions is discussed as well as ground vehicle friction data obtained under similar runway conditions. For a given contaminated runway surface condition, the correlation between ground vehicles and aircraft friction data is identified. The influence of major test parameters on friction measurements such as speed, test tire characteristics, type and amount of surface contaminant, and ambient temperature are discussed. The effect of surface type on wet friction levels is also evaluated from comparative data collected on grooved and ungrooved concrete and asphalt surfaces.

Effects of specific surface area of metallic nickel particles on carbon deposition kinetics

NASA Astrophysics Data System (ADS)

Chen, Zhi-yuan; Bian, Liu-zhen; Yu, Zi-you; Wang, Li-jun; Li, Fu-shen; Chou, Kuo-Chih

2018-02-01

Carbon deposition on nickel powders in methane involves three stages in different reaction temperature ranges. Temperature programing oxidation test and Raman spectrum results indicated the formation of complex and ordered carbon structures at high deposition temperatures. The values of I(D)/ I(G) of the deposited carbon reached 1.86, 1.30, and 1.22 in the first, second, and third stages, respectively. The structure of carbon in the second stage was similar to that in the third stage. Carbon deposited in the first stage rarely contained homogeneous pyrolytic deposit layers. A kinetic model was developed to analyze the carbon deposition behavior in the first stage. The rate-determining step of the first stage is supposed to be interfacial reaction. Based on the investigation of carbon deposition kinetics on nickel powders from different resources, carbon deposition rate is suggested to have a linear relation with the square of specific surface area of nickel particles.

Geophysical, geochemical, and geological investigations of the Dunes geothermal system, Imperial Valley, California

NASA Technical Reports Server (NTRS)

Elders, W. A.; Combs, J.; Coplen, T. B.; Kolesar, P.; Bird, D. K.

1974-01-01

The Dunes anomaly is a water-dominated geothermal system in the alluvium of the Salton Trough, lacking any surface expression. It was discovered by shallow-temperature gradient measurements. A 612-meter-deep test well encountered several temperature-gradient reversals, with a maximum of 105 C at 114 meters. The program involves surface geophysics, including electrical, gravity, and seismic methods, down-hole geophysics and petrophysics of core samples, isotopic and chemical studies of water samples, and petrological and geochemical studies of the cores and cuttings. The aim is (1) to determine the source and temperature history of the brines, (2) to understand the interaction between the brines and rocks, and (3) to determine the areal extent, nature, origin, and history of the geothermal system. These studies are designed to provide better definition of exploration targets for hidden geothermal anomalies and to contribute to improved techniques of exploration and resource assessment.

A mosaic infrared sensor for space astronomy, phase 3

NASA Technical Reports Server (NTRS)

Sood, A. K.

1985-01-01

Short wavelength (1 to 3 micron) HgCdTe mosaic detector arrays for space astronomy purposes were fabricated and studied. Honeywell will test and analyze these arrays at moderate temperatures (300-130K). Low temperature testing will be performed at the University of Hawaii. Short wavelength mosaic arrays were fabricated on three wafers and one array from each wafer was tested and analyzed. The p-type base carrier concentration on these wafers was an order of magnitude lower than typically used so far on this program (10 to the 14/cc as compared to 10 to the 15/cc). Tunneling currents are expected to decrease with this decrease in carrier concentration, resulting in improved performance at very low temperatures. The risk with such a low carrier concentration is that fixed charge in the surface passivating layer must be carefully controlled to prevent surface inversion layers.

CCl 4 chemistry on the magnetite selvedge of single-crystal hematite: competitive surface reactions

NASA Astrophysics Data System (ADS)

Adib, K.; Camillone, N., III; Fitts, J. P.; Rim, K. T.; Flynn, G. W.; Joyce, S. A.; Osgood, R. M., Jr.

2002-01-01

Temperature programmed reaction/desorption (TPR/D) studies were undertaken to characterize the surface chemistry which occurs between CCl 4 and the Fe 3O 4 (1 1 1) selvedge of single crystal α-Fe 2O 3 (0 0 0 1). Six separate desorption events are clearly observed and four desorbing species are identified: CCl 4, OCCl 2, C 2Cl 4 and FeCl 2. It is proposed that OCCl 2, CCl 4 and C 2Cl 4 are produced in reactions involving the same precursor, CCl 2. Three reaction paths compete for the CCl 2 precursor: oxygen atom abstraction (for OCCl 2), molecular recombinative desorption (for CCl 4) and associative desorption (for C 2Cl 4). During the TPR/D temperature ramp, the branching ratio is observed to depend upon temperature and the availability of reactive sites. The data are consistent with a rich site-dependent chemistry.

Enhanced Hydrogen Transport over Palladium Ultrathin Films through Surface Nanostructure Engineering.

PubMed

Abate, Salvatore; Giorgianni, Gianfranco; Gentiluomo, Serena; Centi, Gabriele; Perathoner, Siglinda

2015-11-01

Palladium ultrathin films (around 2 μm) with different surface nanostructures are characterized by TEM, SEM, AFM, and temperature programmed reduction (TPR), and evaluated in terms of H2 permeability and H2-N2 separation. A change in the characteristics of Pd seeds by controlled oxidation-reduction treatments produces films with the same thickness, but different surface and bulk nanostructure. In particular, the films have finer and more homogeneous Pd grains, which results in lower surface roughness. Although all samples show high permeo-selectivity to H2 , the samples with finer grains exhibit enhanced permeance and lower activation energy for H2 transport. The analysis of the data suggests that grain boundaries between the Pd grains at the surface favor H2 transfer from surface to subsurface. Thus, the surface nanostructure plays a relevant role in enhancing the transport of H2 over the Pd ultrathin film, which is an important aspect to develop improved membranes that function at low temperatures and toward new integrated process architectures in H2 and syngas production with enhanced sustainability. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

SURFACE CHEMKIN-III: A Fortran package for analyzing heterogeneous chemical kinetics at a solid-surface - gas-phase interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coltrin, M.E.; Kee, R.J.; Rupley, F.M.

1996-05-01

This document is the user`s manual for the SURFACE CHEMKIN-III package. Together with CHEMKIN-III, this software facilitates the formation, solution, and interpretation of problems involving elementary heterogeneous and gas-phase chemical kinetics in the presence of a solid surface. The package consists of two major software components: an Interpreter and a Surface Subroutine Library. The Interpreter is a program that reads a symbolic description of a user-specified chemical reaction mechanism. One output from the Interpreter is a data file that forms a link to the Surface Subroutine Library, which is a collection of about seventy modular Fortran subroutines that may bemore » called from a user`s application code to return information on chemical production rates and thermodynamic properties. This version of SURFACE CHEMKIN-III includes many modifications to allow treatment of multi-fluid plasma systems, for example modeling the reactions of highly energetic ionic species with a surface. Optional rate expressions allow reaction rates to depend upon ion energy rather than a single thermodynamic temperature. In addition, subroutines treat temperature as an array, allowing an application code to define a different temperature for each species. This version of SURFACE CHEMKIN-III allows use of real (non-integer) stoichiometric coefficients; the reaction order with respect to species concentrations can also be specified independent of the reaction`s stoichiometric coefficients. Several different reaction mechanisms can be specified in the Interpreter input file through the new construct of multiple materials.« less

The HYTHIRM Project: Flight Thermography of the Space Shuttle During the Hypersonic Re-entry

NASA Technical Reports Server (NTRS)

Horvath, Thomas J.; Tomek, Deborah M.; Berger, Karen T.; Zalameda, Joseph N.; Splinter, Scott C.; Krasa, Paul W.; Schwartz, Richard J.; Gibson, David M.; Tietjen, Alan B.; Tack, Steve

2010-01-01

This report describes a NASA Langley led endeavor sponsored by the NASA Engineering Safety Center, the Space Shuttle Program Office and the NASA Aeronautics Research Mission Directorate to demonstrate a quantitative thermal imaging capability. A background and an overview of several multidisciplinary efforts that culminated in the acquisition of high resolution calibrated infrared imagery of the Space Shuttle during hypervelocity atmospheric entry is presented. The successful collection of thermal data has demonstrated the feasibility of obtaining remote high-resolution infrared imagery during hypersonic flight for the accurate measurement of surface temperature. To maximize science and engineering return, the acquisition of quantitative thermal imagery and capability demonstration was targeted towards three recent Shuttle flights - two of which involved flight experiments flown on Discovery. In coordination with these two Shuttle flight experiments, a US Navy NP-3D aircraft was flown between 26-41 nautical miles below Discovery and remotely monitored surface temperature of the Orbiter at Mach 8.4 (STS-119) and Mach 14.7 (STS-128) using a long-range infrared optical package referred to as Cast Glance. This same Navy aircraft successfully monitored the Orbiter Atlantis traveling at approximately Mach 14.3 during its return from the successful Hubble repair mission (STS-125). The purpose of this paper is to describe the systematic approach used by the Hypersonic Thermodynamic Infrared Measurements team to develop and implement a set of mission planning tools designed to establish confidence in the ability of an imaging platform to reliably acquire, track and return global quantitative surface temperatures of the Shuttle during entry. The mission planning tools included a pre-flight capability to predict the infrared signature of the Shuttle. Such tools permitted optimization of the hardware configuration to increase signal-to-noise and to maximize the available dynamic range while mitigating the potential for saturation. Post flight, analysis tools were used to assess atmospheric effects and to convert the 2-D intensity images to 3-D temperature maps of the windward surface. Comparison of the spatially resolved global thermal measurements to surface thermocouples and CFD prediction is made. Successful demonstration of a quantitative, spatially resolved, global temperature measurement on the Shuttle suggests future applications towards hypersonic flight test programs within NASA, DoD and DARPA along with flight test opportunities supporting NASA's project Constellation.

Hypersonic Navier-Stokes Comparisons to Orbiter Flight Data

NASA Technical Reports Server (NTRS)

Candler, Graham V.; Campbell, Charles H.

2010-01-01

During the STS-119 flight of Space Shuttle Discovery, two sets of surface temperature measurements were made. Under the HYTHIRM program3 quantitative thermal images of the windward side of the Orbiter with a were taken. In addition, the Boundary Layer Transition Flight Experiment 4 made thermocouple measurements at discrete locations on the Orbiter wind side. Most of these measurements were made downstream of a surface protuberance designed to trip the boundary layer to turbulent flow. In this paper, we use the US3D computational fluid dynamics code to simulate the Orbiter flow field at conditions corresponding to the STS-119 re-entry. We employ a standard two-temperature, five-species finite-rate model for high-temperature air, and the surface catalysis model of Stewart.1 This work is similar to the analysis of Wood et al . 2 except that we use a different approach for modeling turbulent flow. We use the one-equation Spalart-Allmaras turbulence model8 with compressibility corrections 9 and an approach for tripping the boundary layer at discrete locations. In general, the comparison between the simulations and flight data is remarkably good

Modern average global sea-surface temperature

USGS Publications Warehouse

Schweitzer, Peter N.

1993-01-01

The data contained in this data set are derived from the NOAA Advanced Very High Resolution Radiometer Multichannel Sea Surface Temperature data (AVHRR MCSST), which are obtainable from the Distributed Active Archive Center at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif. The JPL tapes contain weekly images of SST from October 1981 through December 1990 in nine regions of the world ocean: North Atlantic, Eastern North Atlantic, South Atlantic, Agulhas, Indian, Southeast Pacific, Southwest Pacific, Northeast Pacific, and Northwest Pacific. This data set represents the results of calculations carried out on the NOAA data and also contains the source code of the programs that made the calculations. The objective was to derive the average sea-surface temperature of each month and week throughout the whole 10-year series, meaning, for example, that data from January of each year would be averaged together. The result is 12 monthly and 52 weekly images for each of the oceanic regions. Averaging the images in this way tends to reduce the number of grid cells that lack valid data and to suppress interannual variability.

NBS (National Bureau of Standards): Materials measurements

NASA Technical Reports Server (NTRS)

Manning, J. R.

1985-01-01

NBS work for NASA in support of NASA's Microgravity Science and Applications Program under NASA Government Order H-27954B (Properties of Electronic Materials) covering the period April 1, 1984 to March 31, 1985 is described. The work has been carried out in three independent tasks: Task 1--Surface Tensions and Their Variations with Temperature and Impurities; Task 2--Convention during Unidirectional Solidification; Task 3--Measurement of High Temperature Thermodynamic Properties. The results for each task are given separately in the body of the report.

Combining Thermal And Structural Analyses

NASA Technical Reports Server (NTRS)

Winegar, Steven R.

1990-01-01

Computer code makes programs compatible so stresses and deformations calculated. Paper describes computer code combining thermal analysis with structural analysis. Called SNIP (for SINDA-NASTRAN Interfacing Program), code provides interface between finite-difference thermal model of system and finite-element structural model when no node-to-element correlation between models. Eliminates much manual work in converting temperature results of SINDA (Systems Improved Numerical Differencing Analyzer) program into thermal loads for NASTRAN (NASA Structural Analysis) program. Used to analyze concentrating reflectors for solar generation of electric power. Large thermal and structural models needed to predict distortion of surface shapes, and SNIP saves considerable time and effort in combining models.

Optical sensors for mapping temperature and winds in the thermosphere from a CubeSat platform

NASA Astrophysics Data System (ADS)

Sullivan, Stephanie Whalen

The thermosphere is the region between approximately 80 km and 320 or more km above the earth's surface. While many people consider this elevation to be space rather than atmosphere, there is a small quantity of gasses in this region. The behavior of these gasses influences the orbits of satellites, including the International Space Station, causes space weather events, and influences the weather closer to the surface of the earth. Due to the location and characteristics of the thermosphere, even basic properties such as temperature are very difficult to measure. High spatial and temporal resolution data on temperatures and winds in the thermosphere are needed by both the space weather and earth climate modeling communities. To address this need, Space Dynamics Laboratory (SDL) started the Profiling Oxygen Emissions of the Thermosphere (POET) program. POET consists of a series of sensors designed to fly on sounding rockets, CubeSats, or larger platforms, such as IridiumNEXT SensorPODS. While each sensor design is different, they all use characteristics of oxygen optical emissions to measure space weather properties. The POET program builds upon the work of the RAIDS, Odin, and UARS programs. Our intention is to dramatically reduce the costs of building, launching, and operating spectrometers in space, thus allowing for more sensors to be in operation. Continuous long-term data from multiple sensors is necessary to understand the underlying physics required to accurately model and predict weather in the thermosphere. While previous spectrometers have been built to measure winds and temperatures in the thermosphere, they have all been large and expensive. The POET sensors use new focal plane technology and optical designs to overcome these obstacles. This thesis focuses on the testing and calibration of the two POET sensors: the Oxygen Profiling of the Atmospheric Limb (OPAL) temperature sensor and the Split-field Etalon Doppler Imager (SEDI) wind sensor.

Heat transfer to a full-coverage film-cooled surface with 30 degree slant-hole injection

NASA Technical Reports Server (NTRS)

Crawford, M. E.; Kays, W. M.; Moffat, R. J.

1976-01-01

Heat transfer behavior was studied in a turbulent boundary layer with full coverage film cooling through an array of discrete holes and with injection 30 deg to the wall surface in the downstream direction. Stanton numbers were measured for a staggered hole pattern with pitch-to-diameter ratios of 5 and 10, an injection mass flux ratio range of 0.1 to 1.3, and a range of Reynolds number Re sub x of 150,000 to 5 million. Air was used as the working fluid, and the mainstream velocity varied from 9.8 to 34.2 m/sec (32 to 112 ft/sec). The data were taken for secondary injection temperature equal to the wall temperature and also equal to the mainstream temperature. The data may be used to obtain Stanton number as a continuous function of the injectant temperature by use of linear superposition theory. The heat transfer coefficient is defined on the basis of a mainstream-to-wall temperature difference. This definition permits direct comparison of performance between film cooling and transpiration cooling. A differential prediction method was developed to predict the film cooling data base. The method utilizes a two-dimensional boundary layer program with routines to model the injection process and turbulence augmentation. The program marches in the streamwise direction, and when a row of holes is encountered, it stops and injects fluid into the boundary layer. The turbulence level is modeled by algebraically augmenting the mixing length, with the augmentation keyed to a penetration distance for the injected fluid.

The NATA code: Theory and analysis, volume 1. [user manuals (computer programming) - gas dynamics, wind tunnels

NASA Technical Reports Server (NTRS)

Bade, W. L.; Yos, J. M.

1975-01-01

A computer program for calculating quasi-one-dimensional gas flow in axisymmetric and two-dimensional nozzles and rectangular channels is presented. Flow is assumed to start from a state of thermochemical equilibrium at a high temperature in an upstream reservoir. The program provides solutions based on frozen chemistry, chemical equilibrium, and nonequilibrium flow with finite reaction rates. Electronic nonequilibrium effects can be included using a two-temperature model. An approximate laminar boundary layer calculation is given for the shear and heat flux on the nozzle wall. Boundary layer displacement effects on the inviscid flow are considered also. Chemical equilibrium and transport property calculations are provided by subroutines. The code contains precoded thermochemical, chemical kinetic, and transport cross section data for high-temperature air, CO2-N2-Ar mixtures, helium, and argon. It provides calculations of the stagnation conditions on axisymmetric or two-dimensional models, and of the conditions on the flat surface of a blunt wedge. The primary purpose of the code is to describe the flow conditions and test conditions in electric arc heated wind tunnels.

Bearing tester data compilation, analysis, and reporting and bearing math modeling

NASA Technical Reports Server (NTRS)

1983-01-01

The Shaberth bearing analysis computer program was developed for the analysis of jet engine shaft/bearing systems operating above room temperature with normal hydrocarbon lubricants. It is also possible to use this tool to evaluate the shaft bearing systems operating in cryogenics. Effects such as fluid drag, radial temperature gradients, outer race misalignments and clearance changes were simulated and evaluated. In addition, the speed and preload effects on bearing radial stiffness was evaluated. The Shaberth program was also used to provide contact stresses from which contact geometry was calculated to support other analyses such as the determination of cryogenic fluid film thickness in the contacts and evaluation of surface and subsurface stresses necessary for bearing failure evaluation. This program was a vital tool for the thermal analysis of the bearing in that it provides the heat generation rates at the rolling element/race contacts for input into a thermal model of the bearing/shaft assembly.

1DTempPro V2: new features for inferring groundwater/surface-water exchange

USGS Publications Warehouse

Koch, Franklin W.; Voytek, Emily B.; Day-Lewis, Frederick D.; Healy, Richard W.; Briggs, Martin A.; Lane, John W.; Werkema, Dale D.

2016-01-01

A new version of the computer program 1DTempPro extends the original code to include new capabilities for (1) automated parameter estimation, (2) layer heterogeneity, and (3) time-varying specific discharge. The code serves as an interface to the U.S. Geological Survey model VS2DH and supports analysis of vertical one-dimensional temperature profiles under saturated flow conditions to assess groundwater/surface-water exchange and estimate hydraulic conductivity for cases where hydraulic head is known.

Fatigue flaw growth and NDI evaluation for preventing through cracks in spacecraft tankage structures

NASA Technical Reports Server (NTRS)

Pettit, D. E.; Hoeppner, D. W.

1972-01-01

A program was conducted to determine the fatigue-crack propagation behavior of parent and welded 2219-T87 aluminum alloy sheet under controlled cyclic stress conditions in room temperature air and 300 F air. Specimens possessing an initial surface defect of controlled dimensions were cycled under constant load amplitude until the propagating fatigue crack penetrated the back surface of the specimen. A series of precracked specimens were prepared to determine optimum penetrant, X-ray, ultrasonic, and eddy current nondestructive inspection procedures.

Documentation of a deep percolation model for estimating ground-water recharge

USGS Publications Warehouse

Bauer, H.H.; Vaccaro, J.J.

1987-01-01

A deep percolation model, which operates on a daily basis, was developed to estimate long-term average groundwater recharge from precipitation. It has been designed primarily to simulate recharge in large areas with variable weather, soils, and land uses, but it can also be used at any scale. The physical and mathematical concepts of the deep percolation model, its subroutines and data requirements, and input data sequence and formats are documented. The physical processes simulated are soil moisture accumulation, evaporation from bare soil, plant transpiration, surface water runoff, snow accumulation and melt, and accumulation and evaporation of intercepted precipitation. The minimum data sets for the operation of the model are daily values of precipitation and maximum and minimum air temperature, soil thickness and available water capacity, soil texture, and land use. Long-term average annual precipitation, actual daily stream discharge, monthly estimates of base flow, Soil Conservation Service surface runoff curve numbers, land surface altitude-slope-aspect, and temperature lapse rates are optional. The program is written in the FORTRAN 77 language with no enhancements and should run on most computer systems without modifications. Documentation has been prepared so that program modifications may be made for inclusions of additional physical processes or deletion of ones not considered important. (Author 's abstract)

Interaction of D2 with H2O amorphous ice studied by temperature-programmed desorption experiments.

PubMed

Amiaud, L; Fillion, J H; Baouche, S; Dulieu, F; Momeni, A; Lemaire, J L

2006-03-07

The gas-surface interaction of molecular hydrogen D2 with a thin film of porous amorphous solid water (ASW) grown at 10 K by slow vapor deposition has been studied by temperature-programmed-desorption (TPD) experiments. Molecular hydrogen diffuses rapidly into the porous network of the ice. The D2 desorption occurring between 10 and 30 K is considered here as a good probe of the effective surface of ASW interacting with the gas. The desorption kinetics have been systematically measured at various coverages. A careful analysis based on the Arrhenius plot method has provided the D2 binding energies as a function of the coverage. Asymmetric and broad distributions of binding energies were found, with a maximum population peaking at low energy. We propose a model for the desorption kinetics that assumes a complete thermal equilibrium of the molecules with the ice film. The sample is characterized by a distribution of adsorption sites that are filled according to a Fermi-Dirac statistic law. The TPD curves can be simulated and fitted to provide the parameters describing the distribution of the molecules as a function of their binding energy. This approach contributes to a correct description of the interaction of molecular hydrogen with the surface of possibly porous grain mantles in the interstellar medium.

Cloud Properties Derived From GOES-7 for Spring 1994 ARM Intensive Observing Period Using Version 1.0.0 of ARM Satellite Data Analysis Program

NASA Technical Reports Server (NTRS)

Minnis, Patrick; Smith, William L., Jr.; Garber, Donald P.; Ayers, J. Kirk; Doelling, David R.

1995-01-01

This document describes the initial formulation (Version 1.0.0) of the Atmospheric Radiation Measurement (ARM) program satellite data analysis procedures. Techniques are presented for calibrating geostationary satellite data with Sun synchronous satellite radiances and for converting narrowband radiances to top-of-the-atmosphere fluxes and albedos. A methodology is documented for combining geostationary visible and infrared radiances with surface-based temperature observations to derive cloud amount, optical depth, height, thickness, temperature, and albedo. The analysis is limited to two grids centered over the ARM Southern Great Plains central facility in north-central Oklahoma. Daytime data taken during 5 Apr. - 1 May 1994, were analyzed on the 0.3 deg and 0.5 deg latitude-longitude grids that cover areas of 0.9 deg x 0.9 deg and 10 deg x 14 deg, respectively. Conditions ranging from scattered low cumulus to thin cirrus and thick cumulonimbus occurred during the study period. Detailed comparisons with hourly surface observations indicate that the mean cloudiness is within a few percent of the surface-derived sky cover. Formats of the results are also provided. The data can be accessed through the World Wide Web computer network.

An efficient routine for infrared radiative transfer in a cloudy atmosphere

NASA Technical Reports Server (NTRS)

Chou, M. D.; Kouvaris, L.

1981-01-01

A FORTRAN program that calculates the atmospheric cooling rate and infrared fluxes for partly cloudy atmospheres is documented. The IR fluxes in the water bands and the 9.6 and 15 micron bands are calculated at 15 levels ranging from 1.39 mb to the surface. The program is generalized to accept any arbitrary atmospheric temperature and humidity profiles and clouds as input and return the cooling rate and fluxes as output. Sample calculations for various atmospheric profiles and cloud situations are demonstrated.

Potential energy hypersurface and molecular flexibility

NASA Astrophysics Data System (ADS)

Koča, Jaroslav

1993-02-01

The molecular flexibility phenomenon is discussed from the conformational potential energy(hyper) surface (PES) point of view. Flexibility is considered as a product of three terms: thermodynamic, kinetic and geometrical. Several expressions characterizing absolute and relative molecular flexibility are introduced, depending on a subspace studied of the entire conformational space, energy level E of PES as well as absolute temperature. Results obtained by programs DAISY, CICADA and PANIC in conjunction with molecular mechanics program MMX for flexibility analysis of isopentane, 2,2-dimethylpentane and isohexane molecules are introduced.

The Maximum Cross-Correlation approach to detecting translational motions from sequential remote-sensing images

NASA Astrophysics Data System (ADS)

Gao, J.; Lythe, M. B.

1996-06-01

This paper presents the principle of the Maximum Cross-Correlation (MCC) approach in detecting translational motions within dynamic fields from time-sequential remotely sensed images. A C program implementing the approach is presented and illustrated in a flowchart. The program is tested with a pair of sea-surface temperature images derived from Advanced Very High Resolution Radiometer (AVHRR) images near East Cape, New Zealand. Results show that the mean currents in the region have been detected satisfactorily with the approach.

Performance Technology Program (PTP-S II), Volume IX. Evaluation of Reentry Vehicle Nosetip Transition and Heat Transfer in the AEDC Hyperballistics Track G

DTIC Science & Technology

1981-01-01

8217qround test programs, has shown that nosetip related effects markedly influence reentry vehicle performance. In clear air environments e’:he twc major...free flight configuration, extraneous shock layer radia- tion and surface chemiluminescence which may influence the sur- face temperature measurements...in the postf light model may result from range debris or thermal stress in the graphite from the large tem- perature gradients, their influence on

Fundamental studies of catalytic processing of synthetic liquids. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watson, P.R.

1994-06-15

Liquids derived from coal contain relatively high amounts of oxygenated organic compounds, mainly in the form of phenols and furans that are deleterious to the stability and quality of these liquids as fuels. Hydrodeoxygenation (HDO) using Mo/W sulfide catalysts is a promising method to accomplish this removal, but our understanding of the reactions occurring on the catalyst surface during HDO is very limited. Rather than attempting to examine the complexities of real liquids and catalysts we have adopted an approach here using model systems amenable to surface-sensitive techniques that enable us to probe in detail the fundamental processes occurring duringmore » HDO at the surfaces of well-defined model catalysts. The results of this work may lead to the development of more efficient, selective and stable catalysts. Above a S/Mo ratio of about 0.5 ML, furan does not adsorb on sulfided Mo surfaces; as the sulfur coverage is lowered increasing amounts of furan can be adsorbed. Temperature-programmed reaction spectroscopy (TPRS) reveals that C-H, C-C and C-O bond scission occurs on these surfaces. Auger spectra show characteristic changes in the nature and amount of surface carbon. Comparisons with experiments carried out with CO, H{sub 2} and alkenes show that reaction pathways include -- direct abstraction of CO at low temperatures; cracking and release of hydrogen below its normal desorption temperature; dehydrogenatin of adsorbed hydrocarbon fragments; recombination of C and O atoms and dissolution of carbon into the bulk at high temperatures. Performing the adsorption or thermal reaction in 10{sup {minus}5} torr of hydrogen does not change the mode of reaction significantly.« less

Dynamic alterations of hepatocellular function by on-demand elasticity and roughness modulation.

PubMed

Uto, K; Aoyagi, T; DeForest, C A; Ebara, M

2018-05-01

Temperature-responsive cell culture substrates reported here can be dynamically programmed to induce bulk softening and surface roughness changes in the presence of living cells. Alterations in hepatocellular function following temporally controlled substrate softening depend on the extent of stiff mechanical priming prior to user-induced material transition.

Thermal analysis of radiometer containers for the 122m hoop column antenna concept

NASA Technical Reports Server (NTRS)

Dillon-Townes, L. A.

1986-01-01

A thermal analysis was conducted for the 122 Meter Hoop Column Antenna (HCA) Radiometer electronic package containers. The HCA radiometer containers were modeled using the computer aided graphics program, ANVIL 4000, and thermally simulated using two thermal programs, TRASYS and MITAS. The results of the analysis provided relationships between the absorptance-emittance ratio and the average surface temperature of the orbiting radiometer containers. These relationships can be used to specify the surface properties, absorptance and reflectance, of the radiometer containers. This is an initial effort in determining the passive thermal protection needs for the 122 m HCA radiometer containers. Several recommendations are provided which expand this effort so specific passive and active thermal protection systems can be defined and designed.

Advanced Key Technologies for Hot Control Surfaces in Space Re- Entry Vehicles

NASA Astrophysics Data System (ADS)

Dogigli, Michael; Pradier, Alain; Tumino, Giorgio

2002-01-01

(1)MAN Technologie AG, D- 86153 Augsburg, Germany (2,3) ESA, 2200 Noordwijk ZH, The Netherlands Current space re-entry vehicles (e.g. X-38 vehicle 201, the prototype of the International Space Station's Crew Return Vehicle (CRV)) require advanced control surfaces (so called body flaps). Such control surfaces allow the design of smaller and lighter vehicles as well as faster re-entries (compared to the US Shuttle). They are designed as light-weight structures that need no metallic parts, need no mass or volume consuming heat sinks to protect critical components (e.g. bearings) and that can be operated at temperatures of more than 1600 "C in air transferring high mechanical loads (dynamic 40 kN, static 70 kN) at the same time. Because there is a need for CRV and also for Reusable Launch Vehicles (RLV) in future, the European Space Agency (ESA) felt compelled to establish a "Future European Space Transportation and Investigation Program,, (FESTIP) and a "General Support for Technology Program,, (GSTP). One of the main goals of these programs was to develop and qualify key-technologies that are able to master the above mentioned challenging requirements for advanced hot control surfaces and that can be applied for different vehicles. In 1996 MAN Technologie has started the development of hot control surfaces for small lifting bodies in the national program "Heiü Strukturen,,. One of the main results of this program was that especially the following CMC (Ceramic Matrix Composite) key technologies need to be brought up to space flight standard: Complex CMC Structures, CMC Bearings, Metal-to-CMC Joining Technologies, CMC Fasteners, Oxidation Protection Systems and Static and Dynamic Seals. MAN Technologie was contracted by ESA to continue the development and qualification of these key technologies in the frame of the FESTIP and the GSTP program. Development and qualification have successfully been carried out. The key technologies have been applied for the X-38 vehicle 201 body flaps that have been designed, manufactured and qualified also by MAN Technologie in the frame of the national TETRA program ("Technologien fu zuku ftige Raum-Transportsysteme,,). A set of two body flaps will be delivered to NASA at the beginning of 2002 to be integrated into the vehicle 201. Based on development- and qualification tests, the paper describes main technical properties and features of these key technologies that at the same time represent the status of the art. In a qualification test (simultaneous application of thermal and mechanical loads with bearing movements in oxidising atmosphere) of a full scaled CMC bearing, five complete re-entries have been simulated successfully. The paper informs about applied mechanical load and temperature histories as well as about the number of intermittent bearing movements. The paper further informs about the complex CMC attachment structures (attachment of bearing into the body flap and load introduction) that have been qualified together with the CMC bearing. The attachment of the body flap to the vehicle's aft structure has also been qualified by tests in which also four re- entries have been simulated successfully. The attachment in principle is an interfacing structure between the "hot" (1600 "C) CMC body flap and the "cold,, (175 "C) metallic vehicle's aft structure that is able to transfer high me- chanical loads at high temperatures and minimise the heat flux through interfacing components in such way that the temperature difference of 1600 "C 175 "C = 1425 "C is brought down over a structure-length of only 200 mm. The paper informs about applied mechanical load and temperature histories and about the safety margins that have been demonstrated by rupture tests. Mechanical load carrying capacity and thermal resistance of ceramic fasteners have been demonstrated in several development tests which cover tension-, shear-, fatigue- and self locking-tests as well as tests with fastener assemblies representative for the body flaps. The reliability of these fasteners has also been demonstrated in the bearing and body flap qualification tests. In a comprehensive development test campaign, oxidation protection systems as well as repair methods have been developed and successfully applied for the body flap structure and components that reliably can be protected at least for four re-entries. The development of key technologies is continued in the national ASTRA program ("Basistechnologien fu keramische Hochtemperatur-Komponenten,,) and in international programs that among others focus on to improve the reusability of high temperature CMC components for RLVs.

Integrated High Payoff Rocket Propulsion Technology (IHPRPT) SiC Recession Model

NASA Technical Reports Server (NTRS)

Opila, E. J.

2009-01-01

SiC stability and recession rates were modeled in hydrogen/oxygen combustion environments for the Integrated High Payoff Rocket Propulsion Technology (IHPRPT) program. The IHPRPT program is a government and industry program to improve U.S. rocket propulsion systems. Within this program SiC-based ceramic matrix composites are being considered for transpiration cooled injector faceplates or rocket engine thrust chamber liners. Material testing under conditions representative of these environments was conducted at the NASA Glenn Research Center, Cell 22. For the study described herein, SiC degradation was modeled under these Cell 22 test conditions for comparison to actual test results: molar mixture ratio, MR (O2:H2) = 6, material temperatures to 1700 C, combustion gas pressures between 0.34 and 2.10 atm, and gas velocities between 8,000 and 12,000 fps. Recession was calculated assuming rates were controlled by volatility of thermally grown silica limited by gas boundary layer transport. Assumptions for use of this model were explored, including the presence of silica on the SiC surface, laminar gas boundary layer limited volatility, and accuracy of thermochemical data for volatile Si-O-H species. Recession rates were calculated as a function of temperature. It was found that at 1700 C, the highest temperature considered, the calculated recession rates were negligible, about 200 m/h, relative to the expected lifetime of the material. Results compared favorably to testing observations. Other mechanisms contributing to SiC recession are briefly described including consumption of underlying carbon and pitting. A simple expression for liquid flow on the material surface was developed from a one-dimensional treatment of the Navier-Stokes Equation. This relationship is useful to determine under which conditions glassy coatings or thermally grown silica would flow on the material surface, removing protective layers by shear forces. The velocity of liquid flow was found to depend on the gas velocity, the viscosity of gas and liquid, as well as the thickness of the gas boundary layer and the liquid layer. Calculated flow rates of a borosilicate glass coating compared well to flow rates observed for this coating tested on a SiC panel in Cell 22.

Innovative potential of plasma technology

NASA Astrophysics Data System (ADS)

Budaev, V. P.

2017-11-01

The review summarizes recent experimental observations of materials exposed to extreme hot plasma loads in fusion devices and plasma facilities with high-temperature plasma. Plasma load on the material in such devices lead to the stochastic clustering and fractal growth of the surface on scales from tens of nanometers to hundreds of micrometers forming statistical self-similarity of the surface roughness with extremely high specific area. Statistical characteristics of hierarchical granularity and scale invariance of such materials surface qualitatively differ from the properties of the roughness of the ordinary Brownian surface which provides a potential of innovative plasma technologies for synthesis of new nanostructured materials with programmed roughness properties, for hypersonic technologies, for biotechnology and biomedical applications.

Surface reaction modification: The effect of structured overlayers of sulfur on the kinetics and mechanism of the decomposition of formic acid on Pt(111)

NASA Astrophysics Data System (ADS)

Abbas, N.; Madix, R. J.

The reaction of formic acid (DCOOH) on Pt(111), Pt(111)-(2×2)S and Pt(111)-(√3×√3)R30°S surfaces was examined by temperature programmed reaction spectroscopy. On the clean surface formic acid decomposed to yield primarily carbon dioxide and the hydrogenic species (H 2, HD and D 2) at low coverages. Although the formation of water and carbon monoxide via a dehydration reaction was observed at these coverages, the yield of these products was small when compared to the other products of reaction. The evolution of CO 2 at low temperature was ascribed to the decomposition of the formate intermediate. In the presence of sulfur the amount of molecularly adsorbed formic acid decreased up to a factor of three on the (√3×√3)R30°S surface, and a decline in the reactivity of over an order of magnitude was also observed. The only products formed were the hydrogenic species and carbon dioxide. The absence of carbon monoxide indicated that the dehydration pathway was blocked by sulfur. In addition to the low temperature CO 2 peak a high temperature CO 2-producing path was also evident. It was inferred from both the stoichiometry and the coincident evolution of D 2 and CO 2 in the high temperature states that these products also evolved due to the decomposition of the formate intermediate. On increasing the sulfur coverage to one-third monolayer this intermediate was further stabilized, and a predominance of the decomposition via the high temperature path was observed. Stability of the formate intermediate was attributed to inhibition of the decomposition reaction by sulfur atoms. The activation energy for formate decomposition increased from 15 kcal/gmole on the clean surface to 24.3 kcal/gmol on the (√3×√3)R30°S overlayer.

Planetary quarantine program

NASA Technical Reports Server (NTRS)

1971-01-01

A quantitative means was developed to investigate the sensitivity of current spacecraft sterilization plans to variations in D-values. A quantitative expression was derived to represent the distribution of D-values among a population of naturally occurring organisms. An investigation was made of (1) the inactivation of both Bacillus subtilis var. niger spores and Cape Kennedy soil spores by gamma-radiation at room temperature in a nitrogen environment, and (2) the thermoradiation resistance of Cape Kennedy soil spores at elevated temperatures below 125 C. The relation between standard survival experiments with bacterial spores in soils and results obtained on spacecraft surfaces is discussed. Sporocidal properties of aqueous formaldehyde can be increased by elevating the temperature.

Alkaline fuel cell performance investigation

NASA Technical Reports Server (NTRS)

Martin, R. E.; Manzo, M. A.

1988-01-01

An exploratory experimental fuel cell test program was conducted to investigate the performance characteristics of alkaline laboratory research electrodes. The objective of this work was to establish the effect of temperature, pressure, and concentration upon performance and evaluate candidate cathode configurations having the potential for improved performance. The performance characterization tests provided data to empirically establish the effect of temperature, pressure, and concentration upon performance for cell temperatures up to 300 F and reactant pressures up to 200 psia. Evaluation of five gold alloy cathode catalysts revealed that three doped gold alloys had more that two times the surface areas of reference cathodes and therefore offered the best potential for improved performance.

Alkaline fuel cell performance investigation

NASA Technical Reports Server (NTRS)

Martin, R. E.; Manzo, M. A.

1988-01-01

An exploratory experimental fuel cell test program was conducted to investigate the performance characteristics of alkaline laboratory research electrodes. The objective of this work was to establish the effect of temperature, pressure, and concentration upon performance and evaluate candidate cathode configurations having the potential for improved performance. The performance characterization tests provided data to empirically establish the effect of temperature, pressure, and concentration upon performance for cell temperatures up to 300 F and reactant pressures up to 200 psia. Evaluation of five gold alloy cathode catalysts revealed that three doped gold alloys had more than two times the surface areas of reference cathodes and therefore offered the best potential for improved performance.

Global Surface Thermal Inertia Derived from Dawn VIR Observations

NASA Astrophysics Data System (ADS)

Titus, T. N.; Becker, K. J.; Anderson, J.; Capria, M.; Tosi, F.; Prettyman, T. H.; De Sanctis, M. C.; Palomba, E.; Grassi, D.; Capaccioni, F.; Ammannito, E.; Combe, J.; McCord, T. B.; Li, J. Y.; Russell, C. T.; Raymond, C. A.

2012-12-01

Comparisons of surface temperatures, derived from Dawn [1] Visible and Infrared Mapping Spectrometer (VIR-MS) [2] observations , to thermal models suggest that Vesta generally has a low-thermal-inertia surface, between 25 and 35 J m^-2 K^-1 s^-½, consistent with a thick layer of fine-grain material [3]. Temperatures were calculated using a Bayesian approach to nonlinear inversion as described by Tosi et al. [4]. In order to compare observed temperatures of Vesta to model calculations, several geometric and photometric parameters must be known or estimated. These include local mean solar time, latitude, local slope, bond bolometric albedo, and the effective emissivity at 5μm. Local time, latitude, and local slope are calculated using the USGS ISIS software system [5]. We employ a multi-layered thermal-diffusion model called 'KRC' [6], which has been used extensively in the study of Martian thermophysical properties. This thermal model is easily modified for use with Vesta by replacing the Martian ephemeris input with the Vesta ephemeris and disabling the atmosphere. This model calculates surface temperatures throughout an entire Vesta year for specific sets of slope, azimuth, latitude and elevation, and a range of albedo and thermal-inertia values. The ranges of albedo and thermal inertia values create temperature indices that are closely matched to the dates and times observed by VIR. Based on observed temperatures and best-fit KRC thermal models, estimates of the annual mean surface temperatures were found to range from 176 K - 188 K for flat zenith-facing equatorial surfaces, but these temperatures can drop as low as 112 K for polar-facing slopes at mid-latitudes. [7] In this work, we will compare observed temperatures of the surface of Vesta (using data acquired by Dawn VIR-MS [2] during the approach, survey, high-altitude mapping and departure phases) to model temperature results using the KRC thermal model [5]. Where possible, temperature observations from multiple times of day or seasons will be used to better constrain the thermal inertia. The authors gratefully acknowledge the support of the Dawn Instrument, Operations, and Science Teams. This work was funded by the Dawn at Vesta Participating Science Program. [1] C.T. Russell et al. (2004) P&SS, 52, 465-489. [2] M.C. De Sanctis et al. (2011) SSRv 163, 329. [3] M.T. Capria et al. (2012) LPSC XLIII #1863 [4] F. Tosi et al. (2012) LPSC XLIII #1886. [5] J. Anderson et al. (2011) AGU Fall Meeting, #U31A-0009. [6] H.H. Kieffer H., et al. (1977) JGR, 82, 4249-4291. [7] Titus et al. (2012) EPSC, #800.

Interaction of Ester-Functionalized Ionic Liquids with Atomically-Defined Cobalt Oxides Surfaces: Adsorption, Reaction and Thermal Stability.

PubMed

Xu, Tao; Waehler, Tobias; Vecchietti, Julia; Bonivardi, Adrian; Bauer, Tanja; Schwegler, Johannes; Schulz, Peter S; Wasserscheid, Peter; Libuda, Joerg

2017-12-06

Hybrid materials consisting of ionic liquid (ILs) films on supported oxides hold a great potential for applications in electronic and energy materials. In this work, we have performed surface science model studies scrutinizing the interaction of ester-functionalized ILs with atomically defined Co 3 O 4 (111) and CoO(100) surfaces. Both supports are prepared under ultra-high vacuum (UHV) conditions in form of thin films on Ir(100) single crystals. Subsequently, thin films of three ILs, 3-butyl-1-methyl imidazolium bis(trifluoromethyl-sulfonyl) imide ([BMIM][NTf 2 ]), 3-(4-methoxyl-4-oxobutyl)-1-methylimidazolium bis(trifluoromethyl-sulfonyl) imide ([MBMIM][NTf 2 ]), and 3-(4-isopropoxy-4-oxobutyl)-1-methylimidazolium bis(trifluoromethyl-sulfonyl) imide ([IPBMIM][NTf 2 ]), were deposited on these surfaces by physical vapor deposition (PVD). Time-resolved and temperature-programmed infrared reflection absorption spectroscopy (TR-IRAS, TP-IRAS) were applied to monitor in situ the adsorption, film growth, and thermally induced desorption. By TP-IRAS, we determined the multilayer desorption temperature of [BMIM][NTf 2 ] (360±5 K), [MBMIM][NTf 2 ] (380 K) and [IPBMIM][NTf 2 ] (380 K). Upon deposition below the multilayer desorption temperature, all three ILs physisorb on both cobalt oxide surfaces. However, strong orientation effects are observed in the first monolayer, where the [NTf 2 ] - ion interacts with the surface through the SO 2 groups and the CF 3 groups point towards the vacuum. For the two functionalized ILs, the [MBMIM] + and [IPBMIM] + interact with the surface Co 2+ ions of both surfaces via the CO group of their ester function. A very different behavior is found, if the ILs are deposited above the multilayer desorption temperature (400 K). While for [BMIM][NTf 2 ] and [MBMIM][NTf 2 ] a molecularly adsorbed monolayer film is formed, [IPBMIM][NTf 2 ] undergoes a chemical transformation on the CoO(100) surface. Here, the ester group is cleaved and the cation is chemically linked to the surface by formation of a surface carboxylate. The IL-derived species in the monolayer desorb at temperatures around 500 to 550 K. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Radiation heat transfer simulation in a window for a small particle solar receiver using the Monte Carlo method

NASA Astrophysics Data System (ADS)

Whitmore, Alexander Jason

Concentrating solar power systems are currently the predominant solar power technology for generating electricity at the utility scale. The central receiver system, which is a concentrating solar power system, uses a field of mirrors to concentrate solar radiation onto a receiver where a working fluid is heated to drive a turbine. Current central receiver systems operate on a Rankine cycle, which has a large demand for cooling water. This demand for water presents a challenge for the current central receiver systems as the ideal locations for solar power plants have arid climates. An alternative to the current receiver technology is the small particle receiver. The small particle receiver has the potential to produce working fluid temperatures suitable for use in a Brayton cycle which can be more efficient when pressurized to 0.5 MPa. Using a fused quartz window allows solar energy into the receiver while maintaining a pressurized small particle receiver. In this thesis, a detailed numerical investigation for a spectral, three dimensional, cylindrical glass window for a small particle receiver was performed. The window is 1.7 meters in diameter and 0.0254 meters thick. There are three Monte Carlo Ray Trace codes used within this research. The first MCRT code, MIRVAL, was developed by Sandia National Laboratory and modified by a fellow San Diego State University colleague Murat Mecit. This code produces the solar rays on the exterior surface of the window. The second MCRT code was developed by Steve Ruther and Pablo Del Campo. This code models the small particle receiver, which creates the infrared spectral direction flux on the interior surface of the window used in this work. The third MCRT, developed for this work, is used to model radiation heat transfer within the window itself and is coupled to an energy equation solver to produce a temperature distribution. The MCRT program provides a source term to the energy equation. This in turn, produces a new temperature field for the MCRT program; together the equations are solved iteratively. These iterations repeat until convergence is reached for a steady state temperature field. The energy equation was solved using a finite volume method. The window's thermal conductivity is modeled as a function of temperature. This thermal model is used to investigate the effects of different materials, receiver geometries, interior convection coefficients and exterior convection coefficients. To prevent devitrification and the ultimate failure of the window, the window needs to stay below the devitrification temperature of the material. In addition, the temperature gradients within the window need to be kept to a minimum to prevent thermal stresses. A San Diego State University colleague E-Fann Saung uses these temperature maps to insure that the mounting of the window does not produce thermal stresses which can cause cracking in the brittle fused quartz. The simulations in this thesis show that window temperatures are below the devitrification temperature of the window when there are cooling jets on both surfaces of the window. Natural convection on the exterior window surface was explored and it does not provide adequate cooling; therefore forced convection is required. Due to the low thermal conductivity of the window, the edge mounting thermal boundary condition has little effect on the maximum temperature of the window. The simulations also showed that the solar input flux absorbed less than 1% of the incoming radiation while the window absorbed closer to 20% of the infrared radiation emitted by the receiver. The main source of absorbed power in the window is located directly on the interior surface of the window where the infrared radiation is absorbed. The geometry of the receiver has a large impact on the amount of emitted power which reached the interior surface of the window, and using a conical shaped receiver dramatically reduced the receiver's infrared flux on the window. The importance of internal emission is explored within this research. Internal emission produces a more even emission field throughout the receiver than applying radiation surface emission only. Due to a majority of the infrared receiver re-radiation being absorbed right at the interior surface, the surface emission only approximation method produces lower maximum temperatures.

Estimation of Surface Air Temperature from MODIS 1km Resolution Land Surface Temperature Over Northern China

NASA Technical Reports Server (NTRS)

Shen, Suhung; Leptoukh, Gregory G.; Gerasimov, Irina

2010-01-01

Surface air temperature is a critical variable to describe the energy and water cycle of the Earth-atmosphere system and is a key input element for hydrology and land surface models. It is a very important variable in agricultural applications and climate change studies. This is a preliminary study to examine statistical relationships between ground meteorological station measured surface daily maximum/minimum air temperature and satellite remotely sensed land surface temperature from MODIS over the dry and semiarid regions of northern China. Studies were conducted for both MODIS-Terra and MODIS-Aqua by using year 2009 data. Results indicate that the relationships between surface air temperature and remotely sensed land surface temperature are statistically significant. The relationships between the maximum air temperature and daytime land surface temperature depends significantly on land surface types and vegetation index, but the minimum air temperature and nighttime land surface temperature has little dependence on the surface conditions. Based on linear regression relationship between surface air temperature and MODIS land surface temperature, surface maximum and minimum air temperatures are estimated from 1km MODIS land surface temperature under clear sky conditions. The statistical errors (sigma) of the estimated daily maximum (minimum) air temperature is about 3.8 C(3.7 C).

Urban remote sensing applications: TIMS observations of the City of Scottsdale

NASA Technical Reports Server (NTRS)

Christensen, Philip R.; Melendrez, David E.; Anderson, Donald L.; Hamilton, Victoria E.; Wenrich, Melissa L.; Howard, Douglas

1995-01-01

A research program has been initiated between Arizona State University and the City of Scottsdale, Arizona to study the potential applications of TIMS (Thermal Infrared Multispectral Scanner) data for urban scene classification, desert environmental assessment, and change detection. This program is part of a long-term effort to integrate remote sensing observations into state and local planning activities to improve decision making and future planning. Specific test sites include a section of the downtown Scottsdale region that has been mapped in very high detail as part of a pilot program to develop an extensive GIS database. This area thus provides excellent time history of the evolution of the city infrastructure, such as the timing and composition of street repavement. A second area of study includes the McDowell intensive study by state and local agencies to assess potential sites for urban development as well as preservation. These activities are of particular relevance as the Phoenix metropolitan area undergoes major expansion into the surrounding desert areas. The objectives of this study in urban areas are aimed at determining potential applications of TIMS data for classifying and assessing land use and surface temperatures. Land use centers on surface impermeability studies for storm runoff assessment and pollution control. These studies focus on determining the areal abundance of urban vegetation and undeveloped soil. Highly experimental applications include assessment and monitoring of pavement condition. Temperature studies focus on determining swimming pool area and temperature for use in monitoring evaporating and urban water consumption. These activities are of particular relevance as the Phoenix metropolitan area undergoes major expansion into the surrounding desert area.

Interaction of dimethylamine with clean and partially oxidized copper surfaces

NASA Astrophysics Data System (ADS)

Kelber, J. A.; Rogers, J. W.; Banse, B. A.; Koel, B. E.

1990-05-01

The interaction of dimethylamine (DMA) with partially oxidized polycrystalline copper [Cu(poly)] and clean and partially oxidized Cu(110) between 110 and 500 K has been examined using electron stimulated desorption (ESD), high resolution electron energy loss spectroscopy (HREELS) and temperature programmed desorption (TPD). ESD mass spectra of the DMA adsorbed on O/Cu(poly) between 112 and 230 K consistently display peaks at 44 amu [(CH 3) 2N] + and 46 amu [(CH 3) 2NH-H] +, but no significant parent peak at 45 amu [(CH 3) 2NH] +, even though this last feature is prominent in the gas-phase mass spectrum. OH - is not observed at temperatures below 184 K and the yield at higher temperatures is much less than that of O +. HREELS of DMA on clean and oxygen covered Cu(110) obtained at temperatures between 100 and 320 K show characteristic vibrational spectra for molecular DMA and no OH(a) vibrational modes. TPD results show that the desorption profiles of all the major peaks in the DMA mass spectrum follow that of the parent peak with no evidence for production of H 2O. The ESD, HREELS and TPD results all indicate that DMA is molecularly and reversibly adsorbed, with no significant formation of surface hydroxyl species. The results indicate that preferential adsorption of amines from amine/epoxy mixtures onto metal oxide surfaces could passivate the surface and prevent subsequent bonding to the epoxy resin.

Evaluation of high temperature structural adhesives for extended service

NASA Technical Reports Server (NTRS)

Hendricks, C. L.; Hill, S. G.

1984-01-01

High temperature stable adhesive systems were evaluated for potential Supersonic Cruise Research (SCR) vehicle applications. The program was divided into two major phases: Phase I 'Adhesive Screening' evaluated eleven selected polyimide (PI) and polyphenylquinoxaline (PPQ) adhesive resins using eight different titanium (6Al-4V) adherend surface preparations; Phase II 'Adhesive Optimization and Characterization' extensively evaluated two adhesive systems, selected from Phase I studies, for chemical characterization and environmental durability. The adhesive systems which exhibited superior thermal and environmental bond properties were LARC-TPI polyimide and polyphenylquinoxaline both developed at NASA Langley. The latter adhesive system did develop bond failures at extended thermal aging due primarily to incompatibility between the surface preparation and the polymer. However, this study did demonstrate that suitable adhesive systems are available for extended supersonic cruise vehicle design applications.

Skylab program earth resources experiment package: Ground truth data for test sites (SL-2)

NASA Technical Reports Server (NTRS)

1975-01-01

Field measurements were performed at selected ground sites in order to provide comparative calibration measurements of sensors for the Earth Resources Experiment Package. Specifically, the solar radiation (400 to 1300 namometers) and thermal radiation (8-14 micrometers) were measured. Sites employed for the thermal measurements consisted of warm and cold water lakes. The thermal brightness temperature of the lake water, the temperature and humidity profile above the lake, and near surface meteorology (wind speed, pressure, etc.) were measured near the time of overpass. Sites employed for the solar radiation measurements were two desert type sites. Ground measurements consisted of: (1) direct solar radiation - optical depth; (2) diffuse solar radiation; (3) total solar radiation, (4) target directional (normal) reflectance; (5) target hemispherical reflectance; and (6) near surface meteorology.

Using Temperature-Dependent Phenomena at Oxide Surfaces for Species Recognition in Chemical Sensing.

NASA Astrophysics Data System (ADS)

Semancik, Steve; Meier, Douglas; Evju, Jon; Benkstein, Kurt; Boger, Zvi; Montgomery, Chip

2006-03-01

Nanostructured films of SnO2 and TiO2 have been deposited on elements in MEMS arrays to fabricate solid state conductometric gas microsensors. The multilevel platforms within an array, called microhotplates, are individually addressable for localized temperature control and measurement of sensing film electrical conductance. Temperature variations of the microhotplates are employed in thermally-activated CVD oxide film growth, and for rapid temperature-programmed operation of the microsensors. Analytical information on environmental gas phase composition is produced temporally as purposeful thermal fluctuations provide energetic and kinetic control of surface reaction and adsorption/desorption phenomena. Resulting modulations of oxide adsorbate populations cause changing charge transfer behavior and measurable conductance responses. Rich data streams from different sensing films in the arrays have been analyzed by Artificial Neural Networks (ANN) to successfully recognize low concentration species in mixed gases. We illustrate capabilities of the approach and technology in the homeland security area, where dangerous chemicals (TICs, CWSs and CWAs) have been detected at 10-100 ppb levels in interference-spiked air backgrounds.

User's guide to PHREEQC (Version 2) : a computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations

USGS Publications Warehouse

Parkhurst, David L.; Appelo, C.A.J.

1999-01-01

PHREEQC version 2 is a computer program written in the C programming language that is designed to perform a wide variety of low-temperature aqueous geochemical calculations. PHREEQC is based on an ion-association aqueous model and has capabilities for (1) speciation and saturation-index calculations; (2) batch-reaction and one-dimensional (1D) transport calculations involving reversible reactions, which include aqueous, mineral, gas, solid-solution, surface-complexation, and ion-exchange equilibria, and irreversible reactions, which include specified mole transfers of reactants, kinetically controlled reactions, mixing of solutions, and temperature changes; and (3) inverse modeling, which finds sets of mineral and gas mole transfers that account for differences in composition between waters, within specified compositional uncertainty limits.New features in PHREEQC version 2 relative to version 1 include capabilities to simulate dispersion (or diffusion) and stagnant zones in 1D-transport calculations, to model kinetic reactions with user-defined rate expressions, to model the formation or dissolution of ideal, multicomponent or nonideal, binary solid solutions, to model fixed-volume gas phases in addition to fixed-pressure gas phases, to allow the number of surface or exchange sites to vary with the dissolution or precipitation of minerals or kinetic reactants, to include isotope mole balances in inverse modeling calculations, to automatically use multiple sets of convergence parameters, to print user-defined quantities to the primary output file and (or) to a file suitable for importation into a spreadsheet, and to define solution compositions in a format more compatible with spreadsheet programs. This report presents the equations that are the basis for chemical equilibrium, kinetic, transport, and inverse-modeling calculations in PHREEQC; describes the input for the program; and presents examples that demonstrate most of the program's capabilities.

Simulating air temperature in an urban street canyon in all weather conditions using measured data at a reference meteorological station

NASA Astrophysics Data System (ADS)

Erell, E.; Williamson, T.

2006-10-01

A model is proposed that adapts data from a standard meteorological station to provide realistic site-specific air temperature in a city street exposed to the same meso-scale environment. In addition to a rudimentary description of the two sites, the canyon air temperature (CAT) model requires only inputs measured at standard weather stations; yet it is capable of accurately predicting the evolution of air temperature in all weather conditions for extended periods. It simulates the effect of urban geometry on radiant exchange; the effect of moisture availability on latent heat flux; energy stored in the ground and in building surfaces; air flow in the street based on wind above roof height; and the sensible heat flux from individual surfaces and from the street canyon as a whole. The CAT model has been tested on field data measured in a monitoring program carried out in Adelaide, Australia, in 2000-2001. After calibrating the model, predicted air temperature correlated well with measured data in all weather conditions over extended periods. The experimental validation provides additional evidence in support of a number of parameterisation schemes incorporated in the model to account for sensible heat and storage flux.

An investigation of current and future satellite and in-situ data for the remote sensing of the land surface energy balance

NASA Technical Reports Server (NTRS)

Diak, George R.

1994-01-01

This final report from the University of Wisconsin-Madison Cooperative Institute for Meteorological Satellite Studies (CIMSS) summarizes a research program designed to improve our knowledge of the water and energy balance of the land surface through the application of remote sensing and in-situ data sources. The remote sensing data source investigations to be detailed involve surface radiometric ('skin') temperatures and also high-spectral-resolution infrared radiance data from atmospheric sounding instruments projected to be available at the end of the decade, which have shown promising results for evaluating the land-surface water and energy budget. The in-situ data types to be discussed are measurements of the temporal changes of the height of the planetary boundary layer and measurements of air temperature within the planetary boundary layer. Physical models of the land surface, planetary boundary layer and free atmosphere have been used as important tools to interpret the in-situ and remote sensing signals of the surface energy balance. A prototype 'optimal' system for combining multiple data sources into a three-dimensional estimate of the surface energy balance was developed and first results from this system will be detailed. Potential new sources of data for this system and suggested continuation research will also be discussed.

Reaction of methyl formate with VC(1 0 0) and TiC(1 0 0) surfaces

NASA Astrophysics Data System (ADS)

Frantz, Peter; Kim, Hyun I.; Didziulis, Stephen V.; Li, Shuang; Chen, Zhiying; Perry, Scott S.

2005-12-01

The chemistry of the (1 0 0) surface of the tribologically important materials vanadium carbide (VC) and titanium carbide (TiC) with methyl formate (CH 3OCHO) has been studied with X-ray photoelectron spectroscopy (XPS), high resolution electron energy loss spectroscopy (HREELS), and temperature programmed desorption (TPD). The molecule reacts with each surface at temperatures below 150 K, although the extent of reaction is greater on the TiC surface. XPS and HREELS results indicate that the first step in this chemistry is the cleavage of the CH 3O-CHO bond, generating surface methoxy groups (CH 3O-) and either carbon monoxide on VC or a formyl (CHO) group on TiC. The methoxy group reacts further on both surfaces via pathways expected based on previous methanol adsorption studies, primarily decomposing through a formyl intermediate on VC to generate formaldehyde and evolving methanol on TiC. The formyl group formed directly from methyl formate on TiC enables the production and evolution of formaldehyde, and also appears to break down further to the elements. These results indicate a propensity for these carbides to react with esters, leading potentially to the beneficial formation of friction lowering surface films or the deleterious degradation of ester-based lubricants.

One-Pot synthesis of phosphorylated mesoporous carbon heterogeneous catalysts with tailored surface acidity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fulvio, Pasquale F; Mahurin, Shannon Mark; Mayes, Richard T

2012-01-01

Soft-templated phosphorylated mesoporous carbons with homogeneous distributions of phosphate groups were prepared by a 'one-pot' synthesis method using mixtures of phosphoric acid with hydrochloric, or nitric acids in the presence of Pluronic F127 triblock copolymer. Adjusting the various ratios of phosphoric acid used in these mixtures resulted in carbons with distinct adsorption, structural and surface acidity properties. The pore size distributions (PSDs) from nitrogen adsorption at -196 C showed that mesoporous carbons exhibit specific surface areas as high as 551 m{sup 2}/g and mesopores as large as 13 nm. Both structural ordering of the mesopores and the final phosphate contentsmore » were strongly dependent on the ratios of H{sub 3}PO{sub 4} in the synthesis gels, as shown by transmission electron microscopy (TEM), X-ray photoelectron (XPS) and energy dispersive X-ray spectroscopy (EDS). The number of surface acid sites determined from temperature programmed desorption of ammonia (NH{sub 3}-TPD) were in the range of 0.3-1.5 mmol/g while the active surface areas are estimated to comprise 5-54% of the total surface areas. Finally, the conversion temperatures for the isopropanol dehydration were lowered by as much as 100 C by transitioning from the least acidic to the most acidic catalysts surface.« less

ASRM Case Insulation development

NASA Technical Reports Server (NTRS)

Tam, W. F. S.; Bell, M.

1993-01-01

The ASRM Case Insulation Program used design of experiments to develop a high performance case insulation. The program traded-off more than thirty properties in areas of ablation performance, material properties, processibility, bonding/aging. Kevlar pulp was found to be the most significant factor. The low-molecular weight ethylene propylene diene monomer, EPDM was the second most significant factor. The curative was the third most significant factor. The tackifier was the fourth most significant factor. The stripwinding process for applying the insulation onto the case inner surfaces was also studied. The parameters selected for experiment were extruder speed, upper roller temperature and extruder nozzle temperature. The extrudability results showed that non-Kevlar filled formulations displayed optimum edges but poor thickness continuity. High Kevlar filled formulations displayed optimum thickness continuity but poor strip edge ratings.

ASRM Case Insulation development

NASA Astrophysics Data System (ADS)

Tam, W. F. S.; Bell, M.

1993-06-01

The ASRM Case Insulation Program used design of experiments to develop a high performance case insulation. The program traded-off more than thirty properties in areas of ablation performance, material properties, processibility, bonding/aging. Kevlar pulp was found to be the most significant factor. The low-molecular weight ethylene propylene diene monomer, EPDM was the second most significant factor. The curative was the third most significant factor. The tackifier was the fourth most significant factor. The stripwinding process for applying the insulation onto the case inner surfaces was also studied. The parameters selected for experiment were extruder speed, upper roller temperature and extruder nozzle temperature. The extrudability results showed that non-Kevlar filled formulations displayed optimum edges but poor thickness continuity. High Kevlar filled formulations displayed optimum thickness continuity but poor strip edge ratings.

Multiproxy record of the last interglacial (MIS 5e) off central and northern California, U.S.A., from Ocean Drilling Program sites 1018 and 1020

USGS Publications Warehouse

Poore, Richard Z.; Dowsett, H.J.; Barron, J.A.; Heusser, L.; Ravelo, A.C.; Mix, A.

2000-01-01

Environmental and climatic conditions during the last interglacial (about 125,000 years ago) along the Central and Northern California coastal region are interpreted from study of marine cores recovered by the Ocean Drilling Program at sites 1018 and 1020. Marine microfossil and pollen assemblages, oxygen isotopes in benthic foraminifers, physical properties, and calcium carbonate contents of cored sediments are proxies indicating strong links between the marine and terrestrial environments during marine isotope stage 5 (MIS 5). At the beginning of the last interglacial (MIS 5e), reduction in global ice volume, increase in surface temperature, and warming of air temperature along the Central and Northern California coast were synchronous within the resolution of our sampling record.

Heat Pipe Materials Compatibility

NASA Technical Reports Server (NTRS)

Eninger, J. E.; Fleischman, G. L.; Luedke, E. E.

1976-01-01

An experimental program to evaluate noncondensable gas generation in ammonia heat pipes was completed. A total of 37 heat pipes made of aluminum, stainless steel and combinations of these materials were processed by various techniques, operated at different temperatures and tested at low temperature to quantitatively determine gas generation rates. In order of increasing stability are aluminum/stainless combination, all aluminum and all stainless heat pipes. One interesting result is the identification of intentionally introduced water in the ammonia during a reflux step as a means of surface passivation to reduce gas generation in stainless-steel/aluminum heat pipes.

NBS (National Bureau of Standards): Materials measurements

NASA Technical Reports Server (NTRS)

Manning, J. R.

1984-01-01

Work in support of NASA's Microgravity Science and Applications Program is described. The results of the following three tasks are given in detail: (1) surface tensions and their variations with temperature and impurities; (2) convection during unidirectional solidification; and (3) measurement of high temperature thermophysical properties. Tasks 1 and 2 were directed toward determining how the reduced gravity obtained in space flight can affect convection and solidification processes. Emphasis in task 3 was on development of levitation and containerless processing techniques which can be applied in space flight to provide thermodynamic measurements of reactive materials.

Orbiting passive microwave sensor simulation applied to soil moisture estimation

NASA Technical Reports Server (NTRS)

Newton, R. W. (Principal Investigator); Clark, B. V.; Pitchford, W. M.; Paris, J. F.

1979-01-01

A sensor/scene simulation program was developed and used to determine the effects of scene heterogeneity, resolution, frequency, look angle, and surface and temperature relations on the performance of a spaceborne passive microwave system designed to estimate soil water information. The ground scene is based on classified LANDSAT images which provide realistic ground classes, as well as geometries. It was determined that the average sensitivity of antenna temperature to soil moisture improves as the antenna footprint size increased. Also, the precision (or variability) of the sensitivity changes as a function of resolution.

Alloy Design Workbench-Surface Modeling Package Developed

NASA Technical Reports Server (NTRS)

Abel, Phillip B.; Noebe, Ronald D.; Bozzolo, Guillermo H.; Good, Brian S.; Daugherty, Elaine S.

2003-01-01

NASA Glenn Research Center's Computational Materials Group has integrated a graphical user interface with in-house-developed surface modeling capabilities, with the goal of using computationally efficient atomistic simulations to aid the development of advanced aerospace materials, through the modeling of alloy surfaces, surface alloys, and segregation. The software is also ideal for modeling nanomaterials, since surface and interfacial effects can dominate material behavior and properties at this level. Through the combination of an accurate atomistic surface modeling methodology and an efficient computational engine, it is now possible to directly model these types of surface phenomenon and metallic nanostructures without a supercomputer. Fulfilling a High Operating Temperature Propulsion Components (HOTPC) project level-I milestone, a graphical user interface was created for a suite of quantum approximate atomistic materials modeling Fortran programs developed at Glenn. The resulting "Alloy Design Workbench-Surface Modeling Package" (ADW-SMP) is the combination of proven quantum approximate Bozzolo-Ferrante-Smith (BFS) algorithms (refs. 1 and 2) with a productivity-enhancing graphical front end. Written in the portable, platform independent Java programming language, the graphical user interface calls on extensively tested Fortran programs running in the background for the detailed computational tasks. Designed to run on desktop computers, the package has been deployed on PC, Mac, and SGI computer systems. The graphical user interface integrates two modes of computational materials exploration. One mode uses Monte Carlo simulations to determine lowest energy equilibrium configurations. The second approach is an interactive "what if" comparison of atomic configuration energies, designed to provide real-time insight into the underlying drivers of alloying processes.

Development of advanced material composites for use as internal insulation for LH2 tanks (gas layer concept)

NASA Technical Reports Server (NTRS)

Gille, J. P.

1972-01-01

A program is described that was conducted to develop an internal insulation system for potential application to the liquid hydrogen tanks of a reusable booster, where the tanks would be subjected to repeated high temperatures. The design of the internal insulation is based on a unique gas layer concept, in which capillary or surface tension effects are used to maintain a stable gas layer, within a cellular core structure, between the tank wall and the contained liquid hydrogen. Specific objectives were to select materials for insulation systems that would be compatible with wall temperatures of 350 F and 650 F during reentry into the earth's atmosphere, and to fabricate and test insulation systems under conditions simulating the operating environment. A materials test program was conducted to evaluate the properties of candidate materials at elevated temperatures and at the temperature of liquid hydrogen, and to determine the compatibility of the materials with a hydrogen atmosphere at the appropriate elevated temperature. The materials that were finally selected included Kapton polyimide films, silicone adhesives, fiber glass batting, and in the case of the 350 F system, Teflon film.

Evaluation of geophysical parameters measured by the Nimbus-7 microwave radiometer for the TOGA Heat Exchange Project

NASA Technical Reports Server (NTRS)

Liu, W. Timothy; Mock, Donald R.

1986-01-01

The data distributed by the National Space Science Data Center on the Geophysical parameters of precipitable water, sea surface temperature, and surface-level wind speed, measured by the Scanning Multichannel Microwave Radiometer (SMMR) on Nimbus-7, are evaluated with in situ measurements between Jan. 1980 and Oct. 1983 over the tropical oceans. In tracking annual cycles and the 1982-83 E1 Nino/Southern Oscillation episode, the radiometer measurements are coherent with sea surface temperatures and surface-level wind speeds measured at equatorial buoys and with precipitable water derived from radiosonde soundings at tropical island stations. However, there are differences between SMMR and in situ measurements. Corrections based on radiosonde and ship data were derived supplementing correction formulae suggested in the databook. This study is the initial evaluation of the data for quantitative description of the 1982-83 E1 Nino/Southern Oscillation episode. It paves the way for determination of the ocean-atmosphere moisture and latent heat exchanges, a priority of the Tropical Ocean and Global Atmosphere (TOGA) Heat Exchange Program.

Adsorption and electron-induced polymerization of methyl methacrylate on Ru(101xAF0)

NASA Astrophysics Data System (ADS)

Hedhili, M. N.; Yakshinskiy, B. V.; Wasielewski, R.; Ciszewski, A.; Madey, T. E.

2008-05-01

The adsorption and electron irradiation of methyl methacrylate (MMA) on a Ru(101¯0) surface have been studied using x-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD), and low energy ion scattering. TPD analysis indicates that a monolayer of MMA chemisorbs and dissociates on the Ru(101¯0) surface. The reaction products observed upon heating include H2, CO, CO2, and a small amount of MMA. Physisorbed multilayers of MMA desorb at temperatures around 170K. Electron irradiation of physisorbed MMA at 140K leads to a modification of the MMA film: The XPS spectra show an increase in thermal stability of the film with retention of the MMA structure, and indicate that electron irradiation induces polymerization. An increase in the electron bombardment fluence induces a degradation of the formed polymerized species and leads to the accumulation of carbon on the Ru surface. These results are relevant to the accumulation of carbon on surfaces of Ru films that serve as capping layers on Mo /Si multilayer mirrors used in extreme ultraviolet lithography.

Methanethiol chemistry on TiO 2-supported Ni clusters

NASA Astrophysics Data System (ADS)

Ozturk, O.; Park, J. B.; Black, T. J.; Rodriguez, J. A.; Hrbek, J.; Chen, D. A.

2008-10-01

The thermal decomposition of methanethiol on Ni clusters grown on TiO 2(1 1 0) was studied by temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS). On all of the Ni surfaces investigated, methane and hydrogen were observed as gaseous products in the TPD experiments, and the only sulfur-containing species that desorbed from the surface was methanethiol itself at low temperatures. The two pathways for methanethiol reaction were hydrodesulfurization to produce methane and nonselective decomposition, which leaves atomic carbon and sulfur on the surface. From high resolution XPS studies, methyl thiolate was identified as the surface intermediate for reaction on TiO 2 and on all of the Ni surfaces investigated, similar to what is observed on single-crystal Ni surfaces. However, the binding sites for methyl thiolate on the 1 ML (monolayer) Ni clusters were different from those on the Ni clusters at coverages of 2.5 ML and higher, based on the S(2p) binding energies for methyl thiolate. No distinct changes in activity or selectivity were observed for the smaller Ni clusters grown at low coverage compared to the more film-like Ni surfaces other than what could be accounted for by changes in total surface area. Interactions between the Ni clusters and the TiO 2 support had two main effects on chemical activity. First, carbon was oxidized by oxygen from the TiO 2 lattice to produce CO at temperatures above 800 K. Second, annealing induced encapsulation of the Ni clusters by reduced TiO x and chemisorbed oxygen. At 800 K, the Ni clusters were totally encapsulated, resulting in a complete loss of methanethiol activity; partial encapsulation at 700 K caused a smaller decrease in activity accompanied by increased oxidation of carbon by lattice oxygen.

Installation Restoration Program. Preliminary Assessment for the 153rd Tactical Airlift Group, Wyoming Air National Guard, Cheyenne Municipal Airport, Cheyenne, Wyoming

DTIC Science & Technology

1988-03-01

Cheyenne area is characterized by semi-arid conditions and large diurnal and annual temperature changes. The summers are generally warm with humidity...contaminants through pathways (groundwater, surface water, soil, and air). MIOCENE - An epoch of the upper Tertiary period, after the Oligocene and before the

Celebrate with SATELLITES: An International Polar Year Partnership to Study Earth's Materials

ERIC Educational Resources Information Center

Hedley, Mikell Lynne; Czajkowski, Kevin; Struble, Janet; Benko, Terri; Shellito, Brad; Sheridan, Scott; Stasiuk, Mandy Munroe

2009-01-01

The SATELLITES program uses geospatial technologies to study surface temperatures of Earth's materials, such as sand, soil, grass, and water. Data are collected using Global Learning and Observations to Benefit the Environment (GLOBE) protocols, which are then used in research projects that are a part of the International Polar Year (IPY).…

The temperature and ion energy dependence of deuterium retention in lithium films

NASA Astrophysics Data System (ADS)

Buzi, Luxherta; Koel, Bruce E.; Skinner, Charles H.

2016-10-01

Lithium conditioning of plasma facing components in magnetic fusion devices has improved plasma performance and lowered hydrogen recycling. For applications of lithium in future high heat flux and long pulse duration machines it is important to understand and parameterize deuterium retention in lithium. This work presents surface science studies of deuterium retention in lithium films as a function of surface temperature, incident deuterium ion energy and flux. Initial experiments are performed on thin (3-30 ML) lithium films deposited on a single crystal molybdenum substrate to avoid effects due to grain boundaries, intrinsic defects and impurities. A monoenergetic and mass-filtered deuterium ion beam was generated in a differentially pumped Colutron ion gun. Auger electron spectroscopy and X-ray photoelectron spectroscopy were used to identify the elemental composition and temperature programmed desorption was used to measure the deuterium retention under the different conditions. Support was provided through DOE Contract Number DE-AC02-09CH11466.

A method to achieve comparable thermal states of car brakes during braking on the road and on a high-speed roll-stand

NASA Astrophysics Data System (ADS)

Wolff, Andrzej

2010-01-01

The temperature of a brake friction surface influences significantly the braking effectiveness. The paper describes a heat transfer process in car brakes. Using a developed program of finite element method, the temperature distributions in brake rotors (disc and drum brake) of a light truck have been calculated. As a preliminary consistency criterion of the brake thermal state in road and roll-stand braking conditions, a balance of the energy cumulated in the brake rotor has been taken into account. As the most reliable consistency criterion an equality of average temperatures of the friction surface has been assumed. The presented method allows to achieve on a roll-stand the analogical thermal states of automotive brakes, which are observed during braking in road conditions. Basing on this method, it is possible to calculate the braking time and force for a high-speed roll-stand. In contrast to the previous papers of the author, new calculation results have been presented.

Insights on How NASA's Earth Observing System (EOS) Monitors Our World Environment

NASA Technical Reports Server (NTRS)

King, Michael D.

2000-01-01

The Earth Observing System (EOS) is a space-based observing system comprised of a series of satellite sensors by which scientists can monitor the Earth, a Data and Information System (EOSDIS) enabling researchers worldwide to access the satellite data, and an interdisciplinary science research program to interpret the satellite data. During this year, four EOS science missions were launched, representing observations of (1) total solar irradiance, (2) Earth radiation budget, (3) land cover and land use change, (4) ocean processes (vector wind, sea surface temperature, and ocean color), (5) atmospheric processes (aerosol and cloud properties, water vapor, and temperature and moisture profiles), and (6) tropospheric chemistry. In succeeding years many more satellites will be launched that will contribute immeasurably to our understanding of the Earth's environment. In this presentation I will describe how scientists are using EOS data to examine land use and natural hazards, environmental air quality, including dust storms over the world's deserts, cloud and radiation properties, sea surface temperature, and winds over the ocean.

Enhanced Fe2O3 Reducibility via Surface Modification with Pd: Characterizing the Synergy within Pd/Fe Catalysts for Hydrodeoxygenation Reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hensley, Alyssa; Hong, Yongchun; Zhang, Renqin

2014-10-03

The synergistic catalysis in the hydrodeoxygenation of phenolic compounds over a Pd/Fe bimetallic surface has been well established. However, the nature of this synergy is still in part a mystery. In this work, we used a combined experimental and theoretical approach to understand a potential function of the surface Pd in the reduction of Pd/Fe2O3. This function of Pd was investigated via the comparison of the reduction properties as well as other physicochemical properties of samples synthesized by the reduction of Fe2O3 nanoparticles with and without surface Pd. Temperature-programmed reduction studies demonstrated the remarkable facilitation of reduction by addition ofmore » Pd, evidenced by a 150 degrees C shift toward lower temperature of the reduction peak of Fe3+. From X-ray photoelectron spectroscopy and theoretical calculation results, the interaction between Pd and the Fe2O3 surface occurs through the exchange of electrons with both the surface Fe and O atoms. This bonding between the Pd and surface oxide elements causes the Pd to partially donate electrons to the oxide surface, making the surface electrons more delocalized. This electron delocalization stabilizes the reduced oxide surfaces, as suggested by the TPR results and theoretical prediction. Therefore, the stabilization of the reduced Fe surface as well as the facilitated water formation by introduction of Pd is expected to significantly contribute to the Pd-Fe synergy in hydrodeoxygenation catalysis.« less

Dynamic response of induced pressures, suckdown, and temperatures for two tandem jet STOVL configurations

NASA Technical Reports Server (NTRS)

Wardwell, Douglas A.; Corsiglia, Victor R.; Kuhn, Richard E.

1992-01-01

NASA Ames Research Center has been conducting a program to improve the methods for predicting the jet-induced lift loss (suckdown) and hot gas ingestion on jet Short Takeoff and Vertical Landing (STOVL) aircraft during hover near the ground. As part of that program, small-scale hover tests were conducted to expand the current data base and to improve upon the current empirical methods for predicting jet-induced lift loss and hot gas ingestion (HGI) effects. This report is one of three data reports covering data obtained from hover tests conducted at Lockheed Aeronautical Systems, Rye Canyon Facility. It will include dynamic (time dependent) test data for both lift loss and HGI parameters (height, nozzle temperature, nozzle pressure ratio, and inlet location). The flat plate models tested were tandem jet configurations with three planform variations and variable position side-by-side sucking inlets mounted above the planform. Temperature time lags from 8-15 seconds were observed before the model temperatures stabilize. This was larger than the expected 1.5-second lag calculated from literature. Several possible explanations for the flow temperatures to stabilize may include some, or all, of the following: thermocouple lag, radiation to the model surface, and heat loss to the ground board. Further investigations are required to understand the reasons for this temperature lag.

Hydrogen retention in Li and Li-C-O films

NASA Astrophysics Data System (ADS)

Buzi, Luxherta; Nelson, Andrew O.; Yang, Yuxin; Kaita, Robert; Koel, Bruce E.

2017-10-01

The efficiency of Li in binding H isotopes has led to reduced recycling in magnetic fusion devices and improved plasma performance. Since elemental Li surfaces are challenging to maintain in fusion devices due to the presence of impurities, parameterizing and understanding the mechanisms for H retention in various Li compounds (Li-C-O), in addition to pure Li, is crucial for Li plasma-facing material applications. To determine H retention in Li and Li-C-O films, measurements were done under ultrahigh vacuum conditions using temperature programmed desorption (TPD). Thin Li films (20 monolayers) were deposited on a nickel single crystal substrate and irradiated with 500 eV H2+ions at surface temperatures from 90K to 520K. Initial measurements on Li and Li-O films showed that the retention was comparable and dropped exponentially with surface temperature, from 95% at 90 K to 35% at 520 K. Auger electron spectroscopy and TPD showed that H was retained as lithium hydride (LiH) in pure Li and as lithium hydroxide (LiOH) in Li2O, which decomposed to H2O and Li2O at temperatures higher than 470K. H retention in Li-C and Li-C-O films will be determined over a similar temperature range, and the sputtering rate of these layers with H ions will also be reported. This material is based upon work supported by the U.S. Department of Energy, Office of Science/Fusion Energy Sciences under Award Number DE-SC0012890.

A Model of Loggerhead Sea Turtle (Caretta caretta) Habitat and Movement in the Oceanic North Pacific

PubMed Central

Abecassis, Melanie; Senina, Inna; Lehodey, Patrick; Gaspar, Philippe; Parker, Denise; Balazs, George; Polovina, Jeffrey

2013-01-01

Habitat preferences for juvenile loggerhead turtles in the North Pacific were investigated with data from two several-year long tagging programs, using 224 satellite transmitters deployed on wild and captive-reared turtles. Animals ranged between 23 and 81 cm in straight carapace length. Tracks were used to investigate changes in temperature preferences and speed of the animals with size. Average sea surface temperatures along the tracks ranged from 18 to 23 °C. Bigger turtles generally experienced larger temperature ranges and were encountered in warmer surface waters. Seasonal differences between small and big turtles suggest that the larger ones dive deeper than the mixed layer and subsequently target warmer surface waters to rewarm. Average swimming speeds were under 1 km/h and increased with size for turtles bigger than 30 cm. However, when expressed in body lengths per second (bl s−1), smaller turtles showed much higher swimming speeds (>1 bl s −1) than bigger ones (0.5 bl s−1). Temperature and speed values at size estimated from the tracks were used to parameterize a habitat-based Eulerian model to predict areas of highest probability of presence in the North Pacific. The model-generated habitat index generally matched the tracks closely, capturing the north-south movements of tracked animals, but the model failed to replicate observed east-west movements, suggesting temperature and foraging preferences are not the only factors driving large-scale loggerhead movements. Model outputs could inform potential bycatch reduction strategies. PMID:24039901

Ultra Stable Microwave Radiometers for Future Sea Surface Salinity Missions

NASA Technical Reports Server (NTRS)

Wilson, William J.; Tanner, Alan B.; Pellerano, Fernando A.; Horgan, Kevin A.

2005-01-01

The NASA Earth Science System Pathfinder (ESSP) mission Aquarius will measure global sea surface salinity with 100-km spatial resolution every 8 days with an average monthly salinity accuracy of 0.2 psu (parts per thousand). This requires an L-band low-noise radiometer with the long-term calibration stability of less than 0.1 K over 8 days. This three-year research program on ultra stable radiometers has addressed the radiometer requirements and configuration necessary to achieve this objective for Aquarius and future ocean salinity missions. The system configuration and component performance have been evaluated with radiometer testbeds at both JPL and GSFC. The research has addressed several areas including component characterization as a function of temperature, a procedure for the measurement and correction for radiometer system non-linearity, noise diode calibration versus temperature, low noise amplifier performance over voltage, and temperature control requirements to achieve the required stability. A breadboard radiometer, utilizing microstrip-based technologies, has been built to demonstrate this long-term stability. This report also presents the results of the radiometer test program, a detailed radiometer noise model, and details of the operational switching sequence optimization that can be used to achieve the low noise and stability requirements. Many of the results of this research have been incorporated into the Aquarius radiometer design and will allow this instrument to achieve its goals.

The black rock series supported SCR catalyst for NO x removal.

PubMed

Xie, Bin; Luo, Hang; Tang, Qing; Du, Jun; Liu, Zuohua; Tao, Changyuan

2017-09-01

Black rock series (BRS) is of great potential for their plenty of valued oxides which include vanadium, iron, alumina and silica oxides, etc. BRS was used for directly preparing of selective catalytic reduction (SCR) catalyst by modifying its surface texture with SiO 2 -TiO 2 sols and regulating its catalytic active constituents with V 2 O 5 and MoO 3 . Consequently, 90% NO removal ratio was obtained within 300-400 °C over the BRS-based catalyst. The structure and properties of the BRS-based catalyst were characterized by the techniques of N 2 adsorption-desorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), H 2 -temperature programmed reduction (H 2 -TPR), and NH 3 -temperature programmed desorption (NH 3 -TPD). The results revealed that the BRS-based catalyst possesses favorable properties for NO x removal, including highly dispersed active components, abundant surface-adsorbed oxygen O α , well redox property, and numerous Brønsted acid sites. Particularly, the BRS-based catalyst exhibited considerable anti-poisoning performance compared with commercial TiO 2 -based catalyst. The former catalyst shows a NO conversion surpassing 80% from 300 to 400 °C for potassium poisoning, and a durability of SO 2 and H 2 O exceeding 85% at temperatures from 300 to 450 °C.

Characterization of the thermal conductivity for Advanced Toughened Uni-piece Fibrous Insulations

NASA Technical Reports Server (NTRS)

Stewart, David A.; Leiser, Daniel B.

1993-01-01

Advanced Toughened Uni-piece Fibrous Insulations (TUFI) is discussed in terms of their thermal response to an arc-jet air stream. A modification of the existing Ames thermal conductivity program to predict the thermal response of these functionally gradient materials is described in the paper. The modified program was used to evaluate the effect of density, surface porosity, and density gradient through the TUFI materials on the thermal response of these insulations. Predictions using a finite-difference code and calculated thermal conductivity values from the modified program were compared with in-depth temperature measurements taken from TUFI insulations during short exposures to arc-jet hypersonic air streams.

Remote sensing of atmosphere and oceans; Proceedings of Symposium 1 and of the Topical Meeting of the 27th COSPAR Plenary Meeting, Espoo, Finland, July 18-29, 1988

NASA Technical Reports Server (NTRS)

Raschke, E. (Editor); Ghazi, A. (Editor); Gower, J. F. R. (Editor); Mccormick, P. (Editor); Gruber, A. (Editor); Hasler, A. F. (Editor)

1989-01-01

Papers are presented on the contribution of space remote sensing observations to the World Climate Research Program and the Global Change Program, covering topics such as space observations for global environmental monitoring, experiments related to land surface fluxes, studies of atmospheric composition, structure, motions, and precipitation, and remote sensing for oceanography, observational studies of the atmosphere, clouds, and the earth radiation budget. Also, papers are given on results from space observations for meteorology, oceanography, and mesoscale atmospheric and ocean processes. The topics include vertical atmospheric soundings, surface water temperature determination, sea level variability, data on the prehurricane atmosphere, linear and circular mesoscale convective systems, Karman vortex clouds, and temporal patterns of phytoplankton abundance.

Materials characterization study of conductive flexible second surface mirrors

NASA Technical Reports Server (NTRS)

Levadou, F.; Bosma, S. J.; Paillous, A.

1981-01-01

The status of prequalification and qualification work on conductive flexible second surface mirrors is described. The basic material is FEP Teflon witn either aluminium or silver vacuum deposited reflectors. The top layer has been made conductive by deposition of layer of a indium oxide. The results of a prequalification program comprised of decontamination, humidity, thermal cycling, thermal shock and vibration tests are presented. Thermo-optical and electrical properties. The results of a prequalification program comprised of decontamination, humidity, thermal cycling, thermal shock and vibration tests are presented. Thermo-optical and electrical properties, the electrostatic behavior of the materials under simulated substorm environment and electrical conductivity at low temperatures are characterized. The effects of simulated ultra violet and particles irradiation on electrical and thermo-optical properties of the materials are also presented.

Personal Computer Program for Chemical Hazard Prediction (D2PC)

DTIC Science & Technology

1987-01-01

20, LENGTH OF SURFACE DOWNWIND (m) LEN ..... 17 3.21 Question 21, FMW, FMV, VAP (mm Hg), BPT (deg K) ............ 17 3.22 Question 22, TIME AFTER...Temperature of stack (CC) VAP Vapor pressure (mm Hg) "VST Velocity of effluent from stack (m/sec WND Transport wind speed (m/sec) WOO Woods type, see...LEN. This is the estimated fetch of the vapor over the wetted surface of the puddle. 3.21 Question 21, FtiW, FMV, VAP (mm Hg), BPT (deg K). If the

Bulk versus surface contributions to the Shubnikov-de Haas Effect

NASA Astrophysics Data System (ADS)

Maniv, E.; Petrushevsky, M.; Lahoud, E.; Ron, A.; Neder, I.; Wiedmann, S.; Guduru, V. K.; Zeitler, U.; Maan, J. C.; Chashka, K.; Kanigel, A.; Dagan, Y.

2013-03-01

Among the bulk materials that are considered as experimental realizations of topological insulators Bi2Se3 is of particular interest due to its large bulk band gap and surface states with a single Dirac cone. It has been recently shown that Bi2Se3 can become superconducting when Cuintercalation is introduced (Hor, Y. S.; Williams, A. J. et al. Phys. Rev. Lett.2010, 104, 057001). We report on transport measurements of cleaved flakes ~1 -100 μm thick of Cu intercalated Bi2Se2. Clear Shubnikov-de Haas oscillations are observed. We study the temperature and angular dependence of these oscillations together with the Hall coefficient at low temperatures for various Cu concentrations. We discuss possible contributions from bulk and the protected surface states to the various transport channels. Support from the infrastructure program of the Israeli Ministry of Science and Technology is acknowledged. Part of this work has been supported by EuroMagNET under the EU Contract No. 228043.

Performance of LI-1542 reusable surface insulation system in a hypersonic stream

NASA Technical Reports Server (NTRS)

Hunt, L. R.; Shideler, J. L.; Weinstein, I.

1976-01-01

The thermal and structural performance LI-1542 reusable surface insulation (RSI) tiles was investigated. The test panel was designed to represent part of the surface structure on a space shuttle orbiter fuselage along a 1250 K isotherm. Aerothermal tests were conducted at a free-stream Mach number of 6.6, a total temperature of 1820 K, Reynolds numbers of 2 millon and 5 million per meter, and dynamic pressures of 26 and 65 kPa. The RSI tiles demonstrated good thermal protection and structural integrity. High temperatures were caused by misalinement in tile height, offset the tile longitudinal alinement, and leakage around thermal seals when differential pressure existed across the panel. The damage tolerance of LI-1542 RSI appeared high. The tile coating crazed early in the test program, but this did not effect the tile integrity. Erosion of the tile edges occurred at forward-facing steps and at the ends of longitudinal gaps because of particle impacts and flow shear.

Surface Characterization of Mesoporous CoOx/SBA-15 Catalyst upon 1,2-Dichloropropane Oxidation.

PubMed

Finocchio, Elisabetta; Gonzalez-Prior, Jonatan; Gutierrez-Ortiz, Jose Ignacio; Lopez-Fonseca, Ruben; Busca, Guido; de Rivas, Beatriz

2018-05-29

The active combustion catalyst that is based on 30 wt % cobalt oxide on mesoporous SBA-15 has been tested in 1,2-dichloropropane oxidation and is characterized by means of FT-IR (Fourier transform infrared spectroscopy) and ammonia-TPD (temperature-programmed desorption). In this work, we report the spectroscopic evidence for the role of surface acidity in chloroalkane conversion. Both Lewis acidity and weakly acidic silanol groups from SBA support are involved in the adsorption and initial conversion steps. Moreover, total oxidation reaction results in the formation of new Bronsted acidic sites, which are likely associated with the generation of HCl at high temperature and its adsorption at the catalyst surface. Highly dispersed Co oxide on the mesoporous support and Co-chloride or oxychloride particles, together with the presence of several families of acidic sites originated from the conditioning effect of reaction products may explain the good activity of this catalyst in the oxidation of Chlorinated Volatile Organic Compounds.

Enhanced capture of elemental mercury by bamboo-based sorbents.

PubMed

Tan, Zengqiang; Xiang, Jun; Su, Sheng; Zeng, Hancai; Zhou, Changsong; Sun, Lushi; Hu, Song; Qiu, Jianrong

2012-11-15

To develop cost-effective sorbent for gas-phase elemental mercury removal, the bamboo charcoal (BC) produced from renewable bamboo and KI modified BC (BC-I) were used for elemental mercury removal. The effect of NO, SO2 on gas-phase Hg0 adsorption by KI modified BC was evaluated on a fixed bed reactor using an online mercury analyzer. BET surface area analysis, temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS) were used to determine the pore structure and surface chemistry of the sorbents. The results show that KI impregnation reduced the sorbents' BET surface area and total pore volume compared with that of the original BC. But the BC-I has excellent adsorption capacity for elemental mercury at a relatively higher temperature of 140 °C and 180 °C. The presence of NO or SO2 could inhibit Hg0 capture, but BC-I has strong anti-poisoning ability. The specific reaction mechanism has been further analyzed. Copyright © 2012 Elsevier B.V. All rights reserved.

Assessment of surface acidity in mesoporous materials containing aluminum and titanium

NASA Astrophysics Data System (ADS)

Araújo, Rinaldo S.; Maia, Débora A. S.; Azevedo, Diana C. S.; Cavalcante, Célio L., Jr.; Rodríguez-Castellón, E.; Jimenez-Lopez, A.

2009-04-01

The surface acidity of mesoporous molecular sieves of aluminum and titanium was evaluated using four different techniques: n-butylamine volumetry, cyclohexylamine thermodesorption, temperature-programmed desorption of ammonia and adsorption of pyridine. The nature, strength and concentration of the acid sites were determined and correlated to the results of a probe reaction of anthracene oxidation to 9,10-anthraquinone (in liquid phase). In general, the surface acidity was highly influenced by the nature, location and coordination of the metal species (Al and Ti) in the mesoporous samples. Moderate to strong Brönsted acid sites were identified for the Al-MCM-41 sample in a large temperature range. For mesoporous materials containing Ti, the acidity was represented by a combination of weak to moderate Brönsted and Lewis acid sites. The Ti-HMS sample exhibits a higher acidity of moderate strength together with a well-balanced concentration of Brönsted and Lewis acid sites, which enhanced both conversion and selectivity in the oxidation reaction of anthracene.

The Impact of Transported Pollution on Arctic Climate

NASA Astrophysics Data System (ADS)

Quinn, P.; Stohl, A.; Arneth, A.; Berntsen, T.; Burkhart, J. F.; Flanner, M. G.; Kupiainen, K.; Shepherd, M.; Shevchenko, V. P.; Skov, H.; Vestreng, V.

2011-12-01

Arctic temperatures have increased at almost twice the global average rate over the past 100 years. Warming in the Arctic has been accompanied by an earlier onset of spring melt, a lengthening of the melt season, changes in the mass balance of the Greenland ice sheet, and a decrease in sea ice extent. Short-lived, climate warming pollutants such as black carbon (BC) have recently gained attention as a target for immediate mitigation of Arctic warming in addition to reductions in long lived greenhouse gases. Model calculations indicate that BC increases surface temperatures within the Arctic primarily through deposition on snow and ice surfaces with a resulting decrease in surface albedo and increase in absorbed solar radiation. In 2009, the Arctic Monitoring and Assessment Program (AMAP) established an Expert Group on BC with the goal of identifying source regions and energy sectors that have the largest impact on Arctic climate. Here we present the results of this work and investigate links between mid-latitude pollutants and Arctic climate.

Eutectic superalloys strengthened by sigma, Ni3CB lamellae and gamma prime, Ni3Al precipitates

NASA Technical Reports Server (NTRS)

Lemkey, F. D.

1973-01-01

By means of a screening and solidification optimization study of certain alloys located on the gamma-sigma liquidus surface within the Ni-Cb-Cr-Al system, alloys with high temperature properties superior to those of all known superalloys were defined. One alloy, Ni - 19.7w/o Cb - 6.0w/o Cr - 2.5w/o Al, directionally solidified at 3 cm/hr met or exceeded each program goal. A second alloy, Ni-21.75 w/o Cb-2.55 w/o Al, although deficient in its inherent oxidation resistance, met the other program goals and combined a remarkable insensitivity of composite microstructure to solidification parameters with excellent low temperature toughness. This investigation demonstrated that useful properties for gas turbine airfoil application have been achieved by reinforcing a strong and tough gamma solid solution matrix containing precipitated gamma prime by a lamellar intermetallic compound Ni3 Cb having greater strength at elevated temperature.

Evaluation of dispersion strengthened nickel-base alloy heat shields for space shuttle application

NASA Technical Reports Server (NTRS)

Johnson, R., Jr.; Killpatrick, D. H.

1976-01-01

The results obtained in a program to evaluate dispersion-strengthened nickel-base alloys for use in a metallic radiative thermal protection system operating at surface temperatures to 1477 K for the space shuttle were presented. Vehicle environments having critical effects on the thermal protection system are defined; TD Ni-20Cr characteristics of material used in the current study are compared with previous results; cyclic load, temperature, and pressure effects on sheet material residual strength are investigated; the effects of braze reinforcement in improving the efficiency of spotwelded joints are evaluated; parametric studies of metallic radiative thermal protection systems are reported; and the design, instrumentation, and testing of full scale subsize heat shield panels in two configurations are described. Initial tests of full scale subsize panels included simulated meteoroid impact tests, simulated entry flight aerodynamic heating, programmed differential pressure loads and temperatures simulating mission conditions, and acoustic tests simulating sound levels experienced during boost flight.

Transformations of C2-C4 alcohols on the surface of a copper catalyst

NASA Astrophysics Data System (ADS)

Magaeva, A. A.; Lyamina, G. V.; Sudakova, N. N.; Shilyaeva, L. P.; Vodyankina, O. V.

2007-10-01

The interaction of monoatomic alcohols C2-C4 with the surface of a copper catalyst preliminarily oxidized under various conditions was studied by the temperature-programmed reaction method to determine the detailed mechanism of partial oxidation. The conditions of oxygen preadsorption on the surface of copper for the preparation of the desired products were determined. The selective formation of carbonyl compounds was shown to occur at the boundary between reduced and oxidized copper surface regions. The role played by Cu2O was the deep oxidation of alcohols to CO2. Alcohols with branched hydrocarbon structures experienced parallel partial oxidation and dehydrogenation, which was related to the high stability of intermediate keto-type compounds.

Integrated analyses in plastics forming

NASA Astrophysics Data System (ADS)

Bo, Wang

This is the thesis which explains the progress made in the analysis, simulation and testing of plastics forming. This progress can be applied to injection and compression mould design. Three activities of plastics forming have been investigated, namely filling analysis, cooling analysis and ejecting analysis. The filling section of plastics forming has been analysed and calculated by using MOLDFLOW and FILLCALC V. software. A comparing of high speed compression moulding and injection moulding has been made. The cooling section of plastics forming has been analysed by using MOLDFLOW software and a finite difference computer program. The latter program can be used as a sample program to calculate the feasibility of cooling different materials to required target temperatures under controlled cooling conditions. The application of thermal imaging has been also introduced to determine the actual process temperatures. Thermal imaging can be used as a powerful tool to analyse mould surface temperatures and to verify the mathematical model. A buckling problem for ejecting section has been modelled and calculated by PATRAN/ABAQUS finite element analysis software and tested. These calculations and analysis are applied to the special case but can be use as an example for general analysis and calculation in the ejection section of plastics forming.

Mars global reference atmosphere model (Mars-GRAM)

NASA Technical Reports Server (NTRS)

Justus, C. G.; James, Bonnie F.

1992-01-01

Mars-GRAM is an empirical model that parameterizes the temperature, pressure, density, and wind structure of the Martian atmosphere from the surface through thermospheric altitudes. In the lower atmosphere of Mars, the model is built around parameterizations of height, latitudinal, longitudinal, and seasonal variations of temperature determined from a survey of published measurements from the Mariner and Viking programs. Pressure and density are inferred from the temperature by making use of the hydrostatic and perfect gas laws relationships. For the upper atmosphere, the thermospheric model of Stewart is used. A hydrostatic interpolation routine is used to insure a smooth transition from the lower portion of the model to the Stewart thermospheric model. Other aspects of the model are discussed.

Environmental Barrier Coatings (EBC) for Ceramic Matrix Composite (CMC) Materials

NASA Technical Reports Server (NTRS)

Lee,Kang

2001-01-01

The upper use temperature of current Environmental Barrier Coatings (EBC's) based on mullite and BSAS (EPM EBC's) is limited to -255 F due to silica volatility, chemical reactions, and high thermal conductivity. Therefore, new EBC s having low CTE, good chemical compatibility, and high melting point (greater than 2700 F ) are being investigated. Sinter-resistant, low thermal conductivity EBC s are strongly desired to achieve the UEET EBC goal of 270 F EBC surface temperature and 30 F AT over long exposures (greater than 1000 hr). Key areas affecting the upper temperature limit of current EBC s as well as the ongoing efforts to develop next generation EBC s in the UEET Program will be discussed.

Fundamental studies on the nature and properties of ceramic fiber insulation

NASA Technical Reports Server (NTRS)

Mueller, J. I.; Whittemore, O. J., Jr.; Scott, W. D.; Miller, A. D.; Smiser, L. W.; Leiser, D. B.

1975-01-01

Silica and mullite fibers used to fabricate reusable surface insulation (RSI) for the space shuttle orbiter may devitrify/recrystallize within the temperature range anticipated upon reentry. This is shown to be dependent upon impurity level, temperature, and time at temperature. It is determined that the effects of the material improvement and optimization program are positive. The degree of crystallinity is shown to have a predominant effect upon the strength of fabricated RSI tile, and limits are determined. Models are developed to predict tensile strengths and shrinkage rates of silica tile based upon readily measurable parameters. Thermal cycling which simulates reentry results in an increase in the crystallinity and in the porosity of tile coatings.

ITER structural design criteria and their extension to advanced reactor blankets*1

NASA Astrophysics Data System (ADS)

Majumdar, S.; Kalinin, G.

2000-12-01

Applications of the recent ITER structural design criteria (ISDC) are illustrated by two components. First, the low-temperature-design rules are applied to copper alloys that are particularly prone to irradiation embrittlement at relatively low fluences at certain temperatures. Allowable stresses are derived and the impact of the embrittlement on allowable surface heat flux of a simple first-wall/limiter design is demonstrated. Next, the high-temperature-design rules of ISDC are applied to evaporation of lithium and vapor extraction (EVOLVE), a blanket design concept currently being investigated under the US Advanced Power Extraction (APEX) program. A single tungsten first-wall tube is considered for thermal and stress analyses by finite-element method.

Method for in-situ restoration of plantinum resistance thermometer calibration

DOEpatents

Carroll, Radford M.

1989-01-01

A method is provided for in-situ restoration of platinum resistance thermometers (PRT's) that have undergone surface oxide contamination and/or strain-related damage causing decalibration. The method, which may be automated using a programmed computer control arrangement, consists of applying a dc heating current to the resistive sensing element of the PRT of sufficient magnitude to heat the element to an annealing temperature and maintaining the temperature for a specified period to restore the element to a stress-free calibration condition. The process anneals the sensing element of the PRT without subjecting the entire PRT assembly to the annealing temperature and may be used in the periodic maintenance of installed PRT's.

Method for in-situ restoration of platinum resistance thermometer calibration

DOEpatents

Carroll, R.M.

1987-10-23

A method is provided for in-situ restoration of platinum resistance thermometers (PRT's) that have undergone surface oxide contamination and/or stain-related damage causing decalibration. The method, which may be automated using a programmed computer control arrangement, consists of applying a dc heating current to the resistive sensing element of the PRT of sufficient magnitude to heat the element to an annealing temperature and maintaining the temperature for a specified period to restore the element to a stress-free calibration condition. The process anneals the sensing element of the PRT without subjecting the entire PRT assembly to the annealing temperature and may be used in the periodic maintenance of installed PRT's. 1 fig.

Neogene sea surface temperature reconstructions from the Southern McMurdo Sound and the McMurdo Ice Shelf (ANDRILL Program, Antarctica)

NASA Astrophysics Data System (ADS)

Sangiorgi, Francesca; Willmott, Veronica; Kim, Jung-Hyun; Schouten, Stefan; Brinkhuis, Henk; Sinninghe Damsté, Jaap S.; Florindo, Fabio; Harwood, David; Naish, Tim; Powell, Ross

2010-05-01

During the austral summers 2006 and 2007 the ANtarctic DRILLing Program (ANDRILL) drilled two cores, each recovering more than 1000m of sediment from below the McMurdo Ice-Shelf (MIS, AND-1B), and sea-ice in Southern McMurdo Sound (SMS, AND-2A), respectively, revealing new information about Neogene Antarctic cryosphere evolution. Core AND-1B was drilled in a more distal location than core AND-2A. With the aim of obtaining important information for the understanding of the history of Antarctic climate and environment during selected interval of the Neogene, we applied novel organic geochemistry proxies such as TEX86 (Tetra Ether IndeX of lipids with 86 carbon atoms) using a new calibration equation specifically developed for polar areas and based on 116 surface sediment samples collected from polar oceans (Kim et al., subm.), and BIT (Branched and Isoprenoid Tetraether), to derive absolute (sea surface) temperature values and to evaluate the relative contribution of soil organic matter versus marine organic matter, respectively. We will present the state-of-the-art of the methodology applied, discussing its advantages and limitations, and the results so far obtained from the analysis of 60 samples from core AND-2A covering the Miocene Climatic Optimum (and the Mid-late Miocene transition) and of 20 pilot samples from core AND-1B covering the late Pliocene.

Propylene oxidation mechanisms and intermediates using in situ soft X-ray fluorescence methods on the Pt(111) surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gabelnick, A.M.; Capitano, A.T.; Kane, S.M.

2000-01-12

The oxidation of propylene preabsorbed on the Pt(111) surface has been characterized in oxygen pressures up to 0.02 Torr using fluorescence yield near-edge spectroscopy (FYNES) and temperature-programmed fluorescence yield near-edge spectroscopy (TP-FYNES) above the carbon K edge. During oxidation of adsorbed propylene, a stable intermediate was observed and characterized using these soft X-ray methods. A general in situ method for determining the stoichiometry of carbon-containing reaction intermediate species has been developed and demonstrated for the first time. Total carbon concentration measured during temperature-programmed reaction studies clearly indicates a reaction intermediate is formed in the 300 K temperature range with amore » surface concentration of 0.55 x 10{sup 15} carbon atoms/cm{sup 2}. By comparing the intensity of the C-H {sigma}* resonance at the magic angle with the intensity in the carbon continuum, the stoichiometry of this intermediate can be determined unambiguously. Based on calibration with molecular propylene (C{sub 3}H{sub 6}) and propylidyne (C{sub 3}H{sub 5}), the intermediate has a C{sub 3}H{sub 5} stoichiometry for oxygen pressures up to 0.02 Torr. A set of normal and glancing angle FYNES spectra above the carbon K edge was used to characterize the bonding and structure of this intermediate. Spectra of known coverages of adsorbed propylene and propylidyne served as standards. The spectra of di-{sigma} propylene, propylidyne, and the intermediate were curve fit as a group with consistent energies and widths of all primary features. Based on this procedure, the intermediate is 1,1,2-tri-{sigma} 1-methylvinyl. The stoichiometry and temperature stability range of the 1-methylvinyl intermediate formed in oxygen pressures up to 0.02 Torr is identical with the stoichiometry and stability of the same intermediate formed during oxidation of preadsorbed propylene by excess coadsorbed atomic oxygen.« less

Facile Dehydrogenation of Ethane on the IrO2(110) Surface.

PubMed

Bian, Yingxue; Kim, Minkyu; Li, Tao; Asthagiri, Aravind; Weaver, Jason F

2018-02-21

Realizing the efficient and selective conversion of ethane to ethylene is important for improving the utilization of hydrocarbon resources, yet remains a major challenge in catalysis. Herein, ethane dehydrogenation on the IrO 2 (110) surface is investigated using temperature-programmed reaction spectroscopy (TPRS) and density functional theory (DFT) calculations. The results show that ethane forms strongly bound σ-complexes on IrO 2 (110) and that a large fraction of the complexes undergo C-H bond cleavage during TPRS at temperatures below 200 K. Continued heating causes as much as 40% of the dissociated ethane to dehydrogenate and desorb as ethylene near 350 K, with the remainder oxidizing to CO x species. Both TPRS and DFT show that ethylene desorption is the rate-controlling step in the conversion of ethane to ethylene on IrO 2 (110) during TPRS. Partial hydrogenation of the IrO 2 (110) surface is found to enhance ethylene production from ethane while suppressing oxidation to CO x species. DFT predicts that hydrogenation of reactive oxygen atoms of the IrO 2 (110) surface effectively deactivates these sites as H atom acceptors, and causes ethylene desorption to become favored over further dehydrogenation and oxidation of ethane-derived species. The study reveals that IrO 2 (110) exhibits an exceptional ability to promote ethane dehydrogenation to ethylene near room temperature, and provides molecular-level insights for understanding how surface properties influence selectivity toward ethylene production.

Computing Reliabilities Of Ceramic Components Subject To Fracture

NASA Technical Reports Server (NTRS)

Nemeth, N. N.; Gyekenyesi, J. P.; Manderscheid, J. M.

1992-01-01

CARES calculates fast-fracture reliability or failure probability of macroscopically isotropic ceramic components. Program uses results from commercial structural-analysis program (MSC/NASTRAN or ANSYS) to evaluate reliability of component in presence of inherent surface- and/or volume-type flaws. Computes measure of reliability by use of finite-element mathematical model applicable to multiple materials in sense model made function of statistical characterizations of many ceramic materials. Reliability analysis uses element stress, temperature, area, and volume outputs, obtained from two-dimensional shell and three-dimensional solid isoparametric or axisymmetric finite elements. Written in FORTRAN 77.

Review of NASA antiskid braking research

NASA Technical Reports Server (NTRS)

Tanner, J. A.

1982-01-01

NASA antiskid braking system research programs are reviewed. These programs include experimental studies of four antiskid systems on the Langley Landing Loads Track, flights tests with a DC-9 airplane, and computer simulation studies. Results from these research efforts include identification of factors contributing to degraded antiskid performance under adverse weather conditions, tire tread temperature measurements during antiskid braking on dry runway surfaces, and an assessment of the accuracy of various brake pressure-torque computer models. This information should lead to the development of better antiskid systems in the future.

Investigation of the Use of Laser Shock Peening for Enhancing Fatigue and Stress Corrosion Cracking Resistance of Nuclear Energy Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vasudevan, Vijay K.; Jackson, John; Teysseyre, Sebastien

The objective of this project, which includes close collaboration with scientists from INL and ANL, is to investigate and demonstrate the use of advanced mechanical surface treatments like laser shock peening (LSP) and ultrasonic nanocrystal surface modification (UNSM) and establish baseline parameters for enhancing the fatigue properties and SCC resistance of nuclear materials like nickel-based alloy 600 and 304 stainless steel. The research program includes the following key elements/tasks: 1) Procurement of Alloy 600 and 304 SS, heat treatment studies; 2) LSP and UNSM processing of base metal and welds/HAZ of alloys 600 and 304; (3) measurement and mapping ofmore » surface and sub-surface residual strains/stresses and microstructural changes as a function of process parameters using novel methods; (4) determination of thermal relaxation of residual stresses (macro and micro) and microstructure evolution with time at high temperatures typical of service conditions and modeling of the kinetics of relaxation; (5) evaluation of the effects of residual stress, near surface microstructure and temperature on SCC and fatigue resistance and associated microstructural mechanisms; and (6) studies of the effects of bulk and surface grain boundary engineering on improvements in the SCC resistance and associated microstructural and cracking mechanisms« less

Evaluation of Surface Fatigue Strength Based on Surface Temperature

NASA Astrophysics Data System (ADS)

Deng, Gang; Nakanishi, Tsutomu

Surface temperature is considered to be an integrated index that is dependent on not only the load and the dimensions at the contact point but also the sliding velocity, rolling velocity, surface roughness, and lubrication conditions. Therefore, the surface durability of rollers and gears can be evaluated more exactly and simply by the use of surface temperature rather than Hertzian stress. In this research, surface temperatures of rollers under different rolling and sliding conditions are measured using a thermocouple. The effects of load P, mean velocity Vm and sliding velocity Vs on surface temperature are clarified. An experimental formula, which expresses the linear relationship between surface temperature and the P0.86Vs1.31Vm-0.83 value, is used to determine surface temperature. By comparing calculated and measured temperature on the tooth surface of a gear, this formula is confirmed to be applicable for gear tooth surface temperature calculation.

Physical Activation of Oil Palm Empty Fruit Bunch via CO2 Activation Gas for CO2 Adsorption

NASA Astrophysics Data System (ADS)

Joseph, C. G.; Quek, K. S.; Daud, W. M. A. W.; Moh, P. Y.

2017-06-01

In this study, different parameters for the preparation of activated carbon were investigated for their yield and CO2 capture capabilities. The activated carbon was prepared from Oil Palm Empty Fruit Bunch (OPEFB) via a 2-step physical activation process. The OPEFB was pyrolyzed under inert conditions at 500 °C and activated via CO2. A 2-factorial design was employed and the effects of activation temperature, activation dwell time and gas flow rate on yield and CO2 capture capabilities were compared and studied. The yield obtained ranged from between 20 - 26, whereby the temperature was determined to be the most significant factor in influencing CO2 uptake. The CO2 capture capacity was determined using Temperature Programmed Desorption (TPD) technique. The CO2 uptake of EFB activated carbon achieved was between 1.85 - 2.09 mmol/g. TPD analysis has shown that the surface of AC were of basic nature. AC was found to be able to withhold the CO2 up to 663°C before maximum desorption occurs. The surface area and pore size of OPEFB obtained from BET analysis is 2.17 m2 g-1 and 0.01 cm3 g-1. After activation, both surface area and pore size increased with a maximum observed surface area and pore size of 548.07 m2 g-1 and 0.26 cm3 g-1. Surface morphology, functional groups, pore size and surface area were analyzed using SEM, FT-IR, TPD and BET.

Solid State Division progress report for period ending September 30, 1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Green, P.H.; Hinton, L.W.

1994-08-01

This report covers research progress in the Solid State Division from April 1, 1992, to September 30, 1993. During this period, the division conducted a broad, interdisciplinary materials research program with emphasis on theoretical solid state physics, neutron scattering, synthesis and characterization of materials, ion beam and laser processing, and the structure of solids and surfaces. This research effort was enhanced by new capabilities in atomic-scale materials characterization, new emphasis on the synthesis and processing of materials, and increased partnering with industry and universities. The theoretical effort included a broad range of analytical studies, as well as a new emphasismore » on numerical simulation stimulated by advances in high-performance computing and by strong interest in related division experimental programs. Superconductivity research continued to advance on a broad front from fundamental mechanisms of high-temperature superconductivity to the development of new materials and processing techniques. The Neutron Scattering Program was characterized by a strong scientific user program and growing diversity represented by new initiatives in complex fluids and residual stress. The national emphasis on materials synthesis and processing was mirrored in division research programs in thin-film processing, surface modification, and crystal growth. Research on advanced processing techniques such as laser ablation, ion implantation, and plasma processing was complemented by strong programs in the characterization of materials and surfaces including ultrahigh resolution scanning transmission electron microscopy, atomic-resolution chemical analysis, synchrotron x-ray research, and scanning tunneling microscopy.« less

Remarkable support effect on the reactivity of Pt/In2O3/MOx catalysts for methanol steam reforming

NASA Astrophysics Data System (ADS)

Liu, Xin; Men, Yong; Wang, Jinguo; He, Rong; Wang, Yuanqiang

2017-10-01

Effects of supports over Pt/In2O3/MOx catalysts with extremely low loading of Pt (1 wt%) and In2O3 loadings (3 wt%) are investigated for the hydrogen production of methanol steam reforming (MSR) in the temperature range of 250-400 °C. Under practical conditions without the pre-reduction, the 1Pt/3In2O3/CeO2 catalyst shows the highly efficient catalytic performance, achieving almost complete methanol conversion (98.7%) and very low CO selectivity of 2.6% at 325 °C. The supported Pt/In2O3 catalysts are characterized by means of Brunauer-Emmett-Teller (BET) surface area, X-ray diffraction (XRD), high-resolution transmission microscopy (HRTEM), temperature programmed reduction with hydrogen (H2-TPR), CO pulse chemisorption, temperature programmed desorption of methanol and water (CH3OH-TPD and H2O-TPD). These demonstrate that the nature of catalyst support of Pt/In2O3/MOx plays crucial roles in the Pt dispersion associated by the strong interaction among Pt, In2O3 and supporting materials and the surface redox properties at low temperature, and thus affects their capability to activate the reactants and determines the catalytic activity of methanol steam reforming. The superior 1Pt/3In2O3/CeO2 catalyst, exhibiting a remarkable reactivity and stability for 32 h on stream, demonstrates its potential for efficient hydrogen production of methanol steam reforming in mobile and de-centralized H2-fueled PEMFC systems.

Evaluating the Impact of the Summit Station, Greenland Radiosonde Program on Science and Forecast Services

NASA Astrophysics Data System (ADS)

Martinez, C. J.; Starkweather, S.; Cox, C. J.; Solomon, A.; Shupe, M.

2015-12-01

Radiosondes are balloon-borne meteorological sensors used to acquire profiles of temperature and humidity. Radiosonde data are essential inputs for numerical weather prediction models and are used for climate research, particularly in the creation of reanalysis products. However, radiosonde programs are costly to maintain, in particular in the remote regions of the Arctic (e.g., $440,000/yr at Summit, Greenland), where only 40 of approximately 1000 routine global launches are made. The climate of this data-sparse region is poorly understood and forecast data assimilation procedures are designed for global applications. Thus, observations may be rejected from the data assimilation because they are too far from the model expectations. For the most cost-efficient deployment of resources and to improve forecasting methods, analyses of the effectiveness of individual radiosonde programs are necessary. Here, we evaluate how radiosondes launched twice daily (0 and 12 UTC) from Summit Station, Greenland, (72.58⁰N, 38.48⁰W, 3210 masl) influence the European Centre for Medium Range Weather Forecasting (ECMWF) operational forecasts from June 2013 through May of 2015. A statistical analysis is conducted to determine the impact of the observations on the forecast model and the meteorological regimes that the model fails to reproduce are identified. Assimilation rates in the inversion layer are lower than any other part of the troposphere. Above the inversion, assimilation rates range from 85%-100%, 60%-98%, and > 99% for temperature, humidity, and wind, respectively. The lowest assimilation rates are found near the surface, possibly associated with biases in the representation of the temperature inversion by the ECMWF model at Summit. Consequently, assimilation rates are lower near the surface during winter when strong temperature inversions are frequently observed. Our findings benefit the scientific community who uses this information for climatological analysis of the Greenland Ice Sheet, and thus further analysis is warranted.

Eye surface temperature detects stress response in budgerigars (Melopsittacus undulatus).

PubMed

Ikkatai, Yuko; Watanabe, Shigeru

2015-08-05

Previous studies have suggested that stressors not only increase body core temperature but also body surface temperature in many animals. However, it remains unclear whether surface temperature could be used as an alternative to directly measure body core temperature, particularly in birds. We investigated whether surface temperature is perceived as a stress response in budgerigars. Budgerigars have been used as popular animal models to investigate various neural mechanisms such as visual perception, vocal learning, and imitation. Developing a new technique to understand the basic physiological mechanism would help neuroscience researchers. First, we found that cloacal temperature correlated with eye surface temperature. Second, eye surface temperature increased after handling stress. Our findings suggest that eye surface temperature is closely related to cloacal temperature and that the stress response can be measured by eye surface temperature in budgerigars.

Study of the temperature rise induced by a focusing transducer with a wide aperture angle on biological tissue containing ribs

NASA Astrophysics Data System (ADS)

Xin, Wang; Jiexing, Lin; Xiaozhou, Liu; Jiehui, Liu; Xiufen, Gong

2016-04-01

We used the spheroidal beam equation to calculate the sound field created by focusing a transducer with a wide aperture angle to obtain the heat deposition, and then we used the Pennes bioheat equation to calculate the temperature field in biological tissue with ribs and to ascertain the effects of rib parameters on the temperature field. The results show that the location and the gap width between the ribs have a great influence on the axial and radial temperature rise of multilayer biological tissue. With a decreasing gap width, the location of the maximum temperature rise moves forward; as the ribs are closer to the transducer surface, the sound energy that passes through the gap between the ribs at the focus decreases, the maximum temperature rise decreases, and the location of the maximum temperature rise moves forward with the ribs. Project supported by the National Basic Research Program of China (Grant Nos. 2012CB921504 and 2011CB707902), the National Natural Science Foundation of China (Grant No. 11274166), the Fundamental Research Funds for the Central Universities, China (Grant No. 020414380001), the Fund from State Key Laboratory of Acoustics, Chinese Academy of Sciences (Grant No. SKLA201401), China Postdoctoral Science Foundation (Grant No. 2013M531313), and the Priority Academic Program Development of Jiangsu Higher Education Institutions and SRF for ROCS, SEM.

Spallation modeling in the Charring Material Thermal Response and Ablation (CMA) computer program

NASA Astrophysics Data System (ADS)

Sullivan, J. M.; Kobayashi, W. S.

1987-06-01

It has been observed during tests of certain laminated composite materials exposed to relatively high continuous wave laser irradiation, that the heated surface will spall. To model this phenomenon, the Charring Material Thermal Response and Ablation code has been updated. In addition to temperature response, in-depth decomposition, and surface recession, thermal and mechanical stresses are calculated. Spall is modeled as a discrete mass removal event occurring when the stresses exceed the ultimate strength of the char through a critical depth. Comparisons are made with test data for a carbon phenolic cylinder exposed to a shock tube environment and for a flat plate Kevlar epoxy test specimen exposed to high intensity laser irradiation. Good agreement is shown; however, the results indicate a requirement for more comprehensive elevated-temperature material properties for further validation.

Thermal-Structural Evaluation of TD Ni-20Cr Thermal Protection System Panels

NASA Technical Reports Server (NTRS)

Eidinoff, H. L.; Rose, L.

1974-01-01

The results of a thermal-structural test program to verify the performance of a metallic/radiative Thermal Protection System (TPS) under reentry conditions are presented. This TPS panel is suitable for multiple reentry, high L/D space vehicles, such as the NASA space shuttle, having surface temperatures up to 1200 C (2200 F). The TPS panel tested consists of a corrugation-stiffened, beaded-skin TD Ni-20Cr metallic heat shield backed by a flexible fibrous quartz and radiative shield insulative system. Test conditions simulated the critical heating and aerodynamic pressure environments expected during 100 repeated missions of a reentry vehicle. Temperatures were measured during each reentry cycle; heat-shield flatness surveys to measure permanent set of the metallic components were made every 10 cycles. The TPS panel, in spite of localized surface failures, performed its designated function.

Heat transfer and pressure measurements for the SSME fuel turbine

NASA Technical Reports Server (NTRS)

Dunn, Michael G.; Kim, Jungho

1991-01-01

A measurement program is underway using the Rocketdyne two-stage Space Shuttle Main Engine (SSME) fuel turbine. The measurements use a very large shock tunnel to produce a short-duration source of heated and pressurized gas which is subsequently passed through the turbine. Within this environment, the turbine is operated at the design values of flow function, stage pressure ratio, stage temperature ratio, and corrected speed. The first stage vane row and the first stage blade row are instrumented in both the spanwise and chordwise directions with pressure transducers and heat flux gages. The specific measurements to be taken include time averaged surface pressure and heat flux distributions on the vane and blade, flow passage static pressure, flow passage total pressure and total temperature distributions, and phase resolved surface pressure and heat flux on the blade.

Preliminary Analysis of a Water Shield for a Surface Power Reactor

NASA Technical Reports Server (NTRS)

Pearson, J. Boise

2006-01-01

A water based shielding system is being investigated for use on initial lunar surface power systems. The use of water may lower overall cost (as compared to development cost for other materials) and simplify operations in the setup and handling. The thermal hydraulic performance of the shield is of significant interest. The mechanism for transferring heat through the shield is natural convection. A simple 1-D thermal model indicates the necessity of natural convection to maintain acceptable temperatures and pressures in the water shield. CFD analysis is done to quantify the natural convection in the shield, and predicts sufficient natural convection to transfer heat through the shield with small temperature gradients. A test program will he designed to experimentally verify the thermal hydraulic performance of the shield, and to anchor the CFD models to experimental results.

Characterization of the liquid Li-solid Mo (1 1 0) interface from classical molecular dynamics for plasma-facing applications

DOE PAGES

Vella, Joseph R.; Chen, Mohan; Fürstenberg, Sven; ...

2017-08-11

An understanding of the wetting properties and a characterization of theinterface between liquid lithium (Li) and solid molybdenum (Mo) are relevant to assessing the efficacy of Li as a plasma-facing component in fusion reactors. Here, a new second-nearest neighbor modified embedded-atom method (2NN MEAM) force eld is parameterized to describe the interactions between Li and Mo. The new force eld reproduces several benchmark properties obtained from first-principles quantum mechanics simulations, including binding curves for Li at three different adsorption sites and the corresponding forces on Li atoms adsorbed on the Mo (110) surface. This force field is then used tomore » study the wetting of liquid Li on the (110) surface of Mo and to examine the Li-Mo interface using molecular dynamics simulations. From droplet simulations, we nd that liquid Li tends to completely wet the perfect Mo (110) surface, in contradiction with previous experimental measurements that found non-zero contact angles for liquid Li on a Mo substrate. However, these experiments were not carried out under ultra-high vacuum conditions or with a perfect (110) Mo surface, suggesting that the presence of impurities, such as oxygen, and surface structure play a crucial role in this wetting process. From thin- lm simulations, it is observed that the first layer of Li on the Mo (110) surface has many solid-like properties such as a low mobility and a larger degree of ordering when compared to layers further away from the surface, even at temperatures well above the bulk melting temperature of Li. Our findings are consistent with temperature-programmed desorption experiments.« less

Characterization of the liquid Li-solid Mo (1 1 0) interface from classical molecular dynamics for plasma-facing applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vella, Joseph R.; Chen, Mohan; Fürstenberg, Sven

An understanding of the wetting properties and a characterization of theinterface between liquid lithium (Li) and solid molybdenum (Mo) are relevant to assessing the efficacy of Li as a plasma-facing component in fusion reactors. Here, a new second-nearest neighbor modified embedded-atom method (2NN MEAM) force eld is parameterized to describe the interactions between Li and Mo. The new force eld reproduces several benchmark properties obtained from first-principles quantum mechanics simulations, including binding curves for Li at three different adsorption sites and the corresponding forces on Li atoms adsorbed on the Mo (110) surface. This force field is then used tomore » study the wetting of liquid Li on the (110) surface of Mo and to examine the Li-Mo interface using molecular dynamics simulations. From droplet simulations, we nd that liquid Li tends to completely wet the perfect Mo (110) surface, in contradiction with previous experimental measurements that found non-zero contact angles for liquid Li on a Mo substrate. However, these experiments were not carried out under ultra-high vacuum conditions or with a perfect (110) Mo surface, suggesting that the presence of impurities, such as oxygen, and surface structure play a crucial role in this wetting process. From thin- lm simulations, it is observed that the first layer of Li on the Mo (110) surface has many solid-like properties such as a low mobility and a larger degree of ordering when compared to layers further away from the surface, even at temperatures well above the bulk melting temperature of Li. Our findings are consistent with temperature-programmed desorption experiments.« less

Characterization of the liquid Li-solid Mo (1 1 0) interface from classical molecular dynamics for plasma-facing applications

NASA Astrophysics Data System (ADS)

Vella, Joseph R.; Chen, Mohan; Fürstenberg, Sven; Stillinger, Frank H.; Carter, Emily A.; Debenedetti, Pablo G.; Panagiotopoulos, Athanassios Z.

2017-11-01

An understanding of the wetting properties and a characterization of the interface between liquid lithium (Li) and solid molybdenum (Mo) are relevant to assessing the efficacy of Li as a plasma-facing component in fusion reactors. In this work, a new second-nearest neighbor modified embedded-atom method (2NN MEAM) force field is parameterized to describe the interactions between Li and Mo. The new force field reproduces several benchmark properties obtained from first-principles quantum mechanics simulations, including binding curves for Li at three different adsorption sites and the corresponding forces on Li atoms adsorbed on the Mo (1 1 0) surface. This force field is then used to study the wetting of liquid Li on the (1 1 0) surface of Mo and to examine the Li-Mo interface using molecular dynamics simulations. From droplet simulations, we find that liquid Li tends to completely wet the perfect Mo (1 1 0) surface, in contradiction with previous experimental measurements that found non-zero contact angles for liquid Li on a Mo substrate. However, these experiments were not carried out under ultra-high vacuum conditions or with a perfect (1 1 0) Mo surface, suggesting that the presence of impurities, such as oxygen, and surface structure play a crucial role in this wetting process. From thin-film simulations, it is observed that the first layer of Li on the Mo (1 1 0) surface has many solid-like properties such as a low mobility and a larger degree of ordering when compared to layers further away from the surface, even at temperatures well above the bulk melting temperature of Li. These findings are consistent with temperature-programmed desorption experiments.

Microstructures and growth mechanisms of GaN films epitaxially grown on AlN/Si hetero-structures by pulsed laser deposition at different temperatures.

PubMed

Wang, Wenliang; Yang, Weijia; Lin, Yunhao; Zhou, Shizhong; Li, Guoqiang

2015-11-13

2 inch-diameter GaN films with homogeneous thickness distribution have been grown on AlN/Si(111) hetero-structures by pulsed laser deposition (PLD) with laser rastering technique. The surface morphology, crystalline quality, and interfacial property of as-grown GaN films are characterized in detail. By optimizing the laser rastering program, the ~300 nm-thick GaN films grown at 750 °C show a root-mean-square (RMS) thickness inhomogeneity of 3.0%, very smooth surface with a RMS surface roughness of 3.0 nm, full-width at half-maximums (FWHMs) for GaN(0002) and GaN(102) X-ray rocking curves of 0.7° and 0.8°, respectively, and sharp and abrupt AlN/GaN hetero-interfaces. With the increase in the growth temperature from 550 to 850 °C, the surface morphology, crystalline quality, and interfacial property of as-grown ~300 nm-thick GaN films are gradually improved at first and then decreased. Based on the characterizations, the corresponding growth mechanisms of GaN films grown on AlN/Si hetero-structures by PLD with various growth temperatures are hence proposed. This work would be beneficial to understanding the further insight of the GaN films grown on Si(111) substrates by PLD for the application of GaN-based devices.

Improved method for producing catalytic carbon and the potential for increasing its use in commercial applications

USGS Publications Warehouse

Kruse, C.W.; Lizzio, A.A.; DeBarr, J.A.; Feizoulof, C.A.

1997-01-01

This paper describes an improved method for producing a catalytic carbon, which was first produced in the late 1960s. The new activated carbon (AC) removes and destroys organic pollutants in aqueous solutions. To determine the effects of altering the pore structure and surface chemistry of activated carbons, carbons differing in the amount of functional groups on their surfaces were prepared in three steps: (1) oxidizing AC with boiling nitric acid, (2) washing oxidized AC with water to remove the acid, and (3) heating oxidized AC to temperatures beteween 100 and 925 ??C. The surfaces of the products were characterized by determining the amount of CO2 and CO evolved during temperature-programmed desorption. Depending on the desorption temperature, these modified carbons showed enhanced adsorptive and/or catalytic properties that included (1) carbon molecular sieves for separating oxygen from nitrogen, (2) increased capacity for adsorbing sulfur dioxide, (3) stronger adsorption of p-nitrophenol from water, and (4) catalysis of dehydrochlorination reactions. A dehydrohalogenation catalyst produced by the oxidation/ desorption steps was found to be similar to one prepared in the 1960s by oxidizing AC with air at 500-700 ??C. The dehydrohalogenation catalyst produced by either the old method or the new method involves an oxidized surface that has been exposed to a 500-700 ??C temperature range. This carbon catalyst retains modified adsorptive properties of the AC from which it is produced. It can be used both to adsorb pollutants from liquid or gaseous streams and to convert them to recyclable products.

Defense Small Business Innovation Research Program (SBIR) FY 1985.

DTIC Science & Technology

1985-01-31

EO)/ INFRARED (IR) COUNTERMEASURES W CATEGORY: Exploratory Development DESCRIPTION: Analysis needs to be performed to determine how to counter weapon...MHz to 2 GHz. Electrically conducting surfaces of interest are cable shields and braids, and optically transparent (to visible and infrared ) screens...conjunction with a particular method of low temperature depositions from organometallics. 37 .. . -. . . . . . -67 - . ... . 43. TITLE: TUNABLE INFRARED LASER

A binary genetic programing model for teleconnection identification between global sea surface temperature and local maximum monthly rainfall events

NASA Astrophysics Data System (ADS)

Danandeh Mehr, Ali; Nourani, Vahid; Hrnjica, Bahrudin; Molajou, Amir

2017-12-01

The effectiveness of genetic programming (GP) for solving regression problems in hydrology has been recognized in recent studies. However, its capability to solve classification problems has not been sufficiently explored so far. This study develops and applies a novel classification-forecasting model, namely Binary GP (BGP), for teleconnection studies between sea surface temperature (SST) variations and maximum monthly rainfall (MMR) events. The BGP integrates certain types of data pre-processing and post-processing methods with conventional GP engine to enhance its ability to solve both regression and classification problems simultaneously. The model was trained and tested using SST series of Black Sea, Mediterranean Sea, and Red Sea as potential predictors as well as classified MMR events at two locations in Iran as predictand. Skill of the model was measured in regard to different rainfall thresholds and SST lags and compared to that of the hybrid decision tree-association rule (DTAR) model available in the literature. The results indicated that the proposed model can identify potential teleconnection signals of surrounding seas beneficial to long-term forecasting of the occurrence of the classified MMR events.

The EUSTACE project: delivering global, daily information on surface air temperature

NASA Astrophysics Data System (ADS)

Rayner, Nick

2017-04-01

Day-to-day variations in surface air temperature affect society in many ways; however, daily surface air temperature measurements are not available everywhere. A global daily analysis cannot be achieved with measurements made in situ alone, so incorporation of satellite retrievals is needed. To achieve this, in the EUSTACE project (2015-June 2018, https://www.eustaceproject.eu) we are developing an understanding of the relationships between traditional (land and marine) surface air temperature measurements and retrievals of surface skin temperature from satellite measurements, i.e. Land Surface Temperature, Ice Surface Temperature, Sea Surface Temperature and Lake Surface Water Temperature. Here we discuss the science needed to produce a fully-global daily analysis (or ensemble of analyses) of surface air temperature on the centennial scale, integrating different ground-based and satellite-borne data types. Information contained in the satellite retrievals is used to create globally-complete fields in the past, using statistical models of how surface air temperature varies in a connected way from place to place. As the data volumes involved are considerable, such work needs to include development of new "Big Data" analysis methods. We will present recent progress along this road in the EUSTACE project: 1. providing new, consistent, multi-component estimates of uncertainty in surface skin temperature retrievals from satellites; 2. identifying inhomogeneities in daily surface air temperature measurement series from weather stations and correcting for these over Europe; 3. estimating surface air temperature over all surfaces of Earth from surface skin temperature retrievals; 4. using new statistical techniques to provide information on higher spatial and temporal scales than currently available, making optimum use of information in data-rich eras. Information will also be given on how interested users can become involved.

The EUSTACE project: delivering global, daily information on surface air temperature

NASA Astrophysics Data System (ADS)

Ghent, D.; Rayner, N. A.

2016-12-01

Day-to-day variations in surface air temperature affect society in many ways; however, daily surface air temperature measurements are not available everywhere. A global daily analysis cannot be achieved with measurements made in situ alone, so incorporation of satellite retrievals is needed. To achieve this, in the EUSTACE project (2015-June 2018, https://www.eustaceproject.eu) we are developing an understanding of the relationships between traditional (land and marine) surface air temperature measurements and retrievals of surface skin temperature from satellite measurements, i.e. Land Surface Temperature, Ice Surface Temperature, Sea Surface Temperature and Lake Surface Water Temperature. Here we discuss the science needed to produce a fully-global daily analysis (or ensemble of analyses) of surface air temperature on the centennial scale, integrating different ground-based and satellite-borne data types. Information contained in the satellite retrievals is used to create globally-complete fields in the past, using statistical models of how surface air temperature varies in a connected way from place to place. As the data volumes involved are considerable, such work needs to include development of new "Big Data" analysis methods. We will present recent progress along this road in the EUSTACE project, i.e.: • providing new, consistent, multi-component estimates of uncertainty in surface skin temperature retrievals from satellites; • identifying inhomogeneities in daily surface air temperature measurement series from weather stations and correcting for these over Europe; • estimating surface air temperature over all surfaces of Earth from surface skin temperature retrievals; • using new statistical techniques to provide information on higher spatial and temporal scales than currently available, making optimum use of information in data-rich eras. Information will also be given on how interested users can become involved.

Development of Sensors for Ceramic Components in Advanced Propulsion Systems. Phase 2; Temperature Sensor Systems Evaluation

NASA Technical Reports Server (NTRS)

Atkinson, W. H.; Cyr, M. A.; Strange, R. R.

1994-01-01

The 'development of sensors for ceramic components in advanced propulsion systems' program is divided into two phases. The objectives of Phase 1 were to analyze, evaluate and recommend sensor concepts for the measurement of surface temperature, strain and heat flux on ceramic components for advanced propulsion systems. The results of this effort were previously published in NASA CR-182111. As a result of Phase 1, three approaches were recommended for further development: pyrometry, thin-film sensors, and thermographic phosphors. The objective of Phase 2 were to fabricate and conduct laboratory demonstration tests of these systems. Six materials, mutually agreed upon by NASA and Pratt & Whitney, were investigated under this program. This report summarizes the Phase 2 effort and provides conclusions and recommendations for each of the categories evaluated.

Mars Global Reference Atmospheric Model 2001 Version (Mars-GRAM 2001): Users Guide

NASA Technical Reports Server (NTRS)

Justus, C. G.; Johnson, D. L.

2001-01-01

This document presents Mars Global Reference Atmospheric Model 2001 Version (Mars-GRAM 2001) and its new features. As with the previous version (mars-2000), all parameterizations fro temperature, pressure, density, and winds versus height, latitude, longitude, time of day, and season (Ls) use input data tables from NASA Ames Mars General Circulation Model (MGCM) for the surface through 80-km altitude and the University of Arizona Mars Thermospheric General Circulation Model (MTGCM) for 80 to 70 km. Mars-GRAM 2001 is based on topography from the Mars Orbiter Laser Altimeter (MOLA) and includes new MGCM data at the topographic surface. A new auxiliary program allows Mars-GRAM output to be used to compute shortwave (solar) and longwave (thermal) radiation at the surface and top of atmosphere. This memorandum includes instructions on obtaining Mars-GRAN source code and data files and for running the program. It also provides sample input and output and an example for incorporating Mars-GRAM as an atmospheric subroutine in a trajectory code.

The inverse Numerical Computer Program FLUX-BOT for estimating Vertical Water Fluxes from Temperature Time-Series.

NASA Astrophysics Data System (ADS)

Trauth, N.; Schmidt, C.; Munz, M.

2016-12-01

Heat as a natural tracer to quantify water fluxes between groundwater and surface water has evolved to a standard hydrological method. Typically, time series of temperatures in the surface water and in the sediment are observed and are subsequently evaluated by a vertical 1D representation of heat transport by advection and dispersion. Several analytical solutions as well as their implementation into user-friendly software exist in order to estimate water fluxes from the observed temperatures. Analytical solutions can be easily implemented but assumptions on the boundary conditions have to be made a priori, e.g. sinusoidal upper temperature boundary. Numerical models offer more flexibility and can handle temperature data which is characterized by irregular variations such as storm-event induced temperature changes and thus cannot readily be incorporated in analytical solutions. This also reduced the effort of data preprocessing such as the extraction of the diurnal temperature variation. We developed a software to estimate water FLUXes Based On Temperatures- FLUX-BOT. FLUX-BOT is a numerical code written in MATLAB which is intended to calculate vertical water fluxes in saturated sediments, based on the inversion of measured temperature time series observed at multiple depths. It applies a cell-centered Crank-Nicolson implicit finite difference scheme to solve the one-dimensional heat advection-conduction equation. Besides its core inverse numerical routines, FLUX-BOT includes functions visualizing the results and functions for performing uncertainty analysis. We provide applications of FLUX-BOT to generic as well as to measured temperature data to demonstrate its performance.

The EUSTACE project: delivering global, daily information on surface air temperature

NASA Astrophysics Data System (ADS)

Ghent, D.; Rayner, N. A.

2017-12-01

Day-to-day variations in surface air temperature affect society in many ways; however, daily surface air temperature measurements are not available everywhere. A global daily analysis cannot be achieved with measurements made in situ alone, so incorporation of satellite retrievals is needed. To achieve this, in the EUSTACE project (2015-2018, https://www.eustaceproject.eu) we have developed an understanding of the relationships between traditional (land and marine) surface air temperature measurements and retrievals of surface skin temperature from satellite measurements, i.e. Land Surface Temperature, Ice Surface Temperature, Sea Surface Temperature and Lake Surface Water Temperature. Here we discuss the science needed to produce a fully-global daily analysis (or ensemble of analyses) of surface air temperature on the centennial scale, integrating different ground-based and satellite-borne data types. Information contained in the satellite retrievals is used to create globally-complete fields in the past, using statistical models of how surface air temperature varies in a connected way from place to place. This includes developing new "Big Data" analysis methods as the data volumes involved are considerable. We will present recent progress along this road in the EUSTACE project, i.e.: • identifying inhomogeneities in daily surface air temperature measurement series from weather stations and correcting for these over Europe; • estimating surface air temperature over all surfaces of Earth from surface skin temperature retrievals; • using new statistical techniques to provide information on higher spatial and temporal scales than currently available, making optimum use of information in data-rich eras. Information will also be given on how interested users can become involved.

Guide to the Revised Ground-Water Flow and Heat Transport Simulator: HYDROTHERM - Version 3

USGS Publications Warehouse

Kipp, Kenneth L.; Hsieh, Paul A.; Charlton, Scott R.

2008-01-01

The HYDROTHERM computer program simulates multi-phase ground-water flow and associated thermal energy transport in three dimensions. It can handle high fluid pressures, up to 1 ? 109 pascals (104 atmospheres), and high temperatures, up to 1,200 degrees Celsius. This report documents the release of Version 3, which includes various additions, modifications, and corrections that have been made to the original simulator. Primary changes to the simulator include: (1) the ability to simulate unconfined ground-water flow, (2) a precipitation-recharge boundary condition, (3) a seepage-surface boundary condition at the land surface, (4) the removal of the limitation that a specified-pressure boundary also have a specified temperature, (5) a new iterative solver for the linear equations based on a generalized minimum-residual method, (6) the ability to use time- or depth-dependent functions for permeability, (7) the conversion of the program code to Fortran 90 to employ dynamic allocation of arrays, and (8) the incorporation of a graphical user interface (GUI) for input and output. The graphical user interface has been developed for defining a simulation, running the HYDROTHERM simulator interactively, and displaying the results. The combination of the graphical user interface and the HYDROTHERM simulator forms the HYDROTHERM INTERACTIVE (HTI) program. HTI can be used for two-dimensional simulations only. New features in Version 3 of the HYDROTHERM simulator have been verified using four test problems. Three problems come from the published literature and one problem was simulated by another partially saturated flow and thermal transport simulator. The test problems include: transient partially saturated vertical infiltration, transient one-dimensional horizontal infiltration, two-dimensional steady-state drainage with a seepage surface, and two-dimensional drainage with coupled heat transport. An example application to a hypothetical stratovolcano system with unconfined ground-water flow is presented in detail. It illustrates the use of HTI with the combination precipitation-recharge and seepage-surface boundary condition, and functions as a tutorial example problem for the new user.

Energy Saving Melting and Revert Reduction Technology: Improved Die Casting Process to Preserve the Life of the Inserts

DOE Office of Scientific and Technical Information (OSTI.GOV)

David Schwam, PI; Xuejun Zhu, Sr. Research Associate

2012-09-30

The goal of this project was to study the combined effects of die design, proper internal cooling and efficient die lubricants on die life. The project targeted improvements in die casting insert life by: Optomized Die Design for Reduced Surface Temperature: The life of die casting dies is significantly shorter when the die is exposed to elevated temperature for significant periods of time. Any die operated under conditions leading to surface temperature in excess of 1050oF undergoes structural changes that reduce its strength. Optimized die design can improve die life significantly. This improvement can be accomplished by means of coolingmore » lines, baffles and bubblers in the die. A key objective of the project was to establish criteria for the minimal distance of the cooling lines from the surface. This effort was supported with alloys and machining by BohlerUddeholm, Dunn Steel, HH Stark and Rex Buckeye. In plant testing and evaluation was conducted as in-kind cost share at St. Clair Die Casting. The Uddeholm Dievar steel evaluated in this program showed superior resistance to thermal fatigue resistance. Based on the experimental evidence, cooling lines could be placed as close as 0.5" from the surface. Die Life Extension by Optimized Die Lubrication: The life of die casting dies is affected by additions made to its surface with the proper lubricants. These lubricants will protect the surface from the considerable temperature peaks that occur when the molten melt enters the die. Dies will reach a significantly higher temperature without this lubricant being applied. The amount and type of the lubricant are critical variables in the die casting process. However, these lubricants must not corrode the die surface. This effort was supported with alloys and machining by BohlerUddeholm, Dunn Steel, HH Stark and Rex Buckeye. In plant testing and evaluation was conducted as in-kind cost share at St. Clair Die Casting. Chem- Trend participated in the program with die lubricants and technical support. Experiments conducted with these lubricants demonstrated good protection of the substrate steel. Graphite and boron nitride used as benchmarks are capable of completely eliminating soldering and washout. However, because of cost and environmental considerations these materials are not widely used in industry. The best water-based die lubricants evaluated in this program were capable of providing similar protection from soldering and washout. In addition to improved part quality and higher production rates, improving die casting processes to preserve the life of the inserts will result in energy savings and a reduction in environmental wastes. Improving die life by means of optimized cooling line placement, baffles and bubblers in the die will allow for reduced die temperatures during processing, saving energy associated with production. The utilization of optimized die lubricants will also reduce heat requirements in addition to reducing waste associated with soldering and washout. This new technology was predicted to result in an average energy savings of 1.1 trillion BTU's/year over a 10 year period. Current (2012) annual energy saving estimates, based on commercial introduction in 2010, a market penetration of 70% by 2020 is 1.26 trillion BTU's/year. Along with these energy savings, reduction of scrap and improvement in casting yield will result in a reduction of the environmental emissions associated with the melting and pouring of the metal which will be saved as a result of this technology. The average annual estimate of CO2 reduction per year through 2020 is 0.025 Million Metric Tons of Carbon Equivalent (MM TCE).« less

Chemical surface modification of polycrystalline platinum thin-films to promote preferential chemisorption of n-hexane, piperidine, and cyclohexane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, V.; Schwank, J.; Gland, J.

In this study, hard/soft Lewis acid-base (HSAB) principles are used to modify a thin-polycrystalline platinum film to promote preferential chemisorption of molecules such as piperidine, n-hexane, and cyclohexane. Specifically, the particle size and electron density distribution of the platinum surface is modified using thermal treatment and co-adsorption of electro-positive and negative species. These studies are conducted in an ultra-high vacuum chamber. The platinum surface is characterized, before and after modification protocols, using a variety of in-situ and ex-situ techniques. These include temperature programmed desorption (TPD), both resistance change and work function measurements, and both X-ray photoelectron spectroscopy and diffraction.

Effect of steam baking on acrylamide formation and browning kinetics of cookies.

PubMed

Isleroglu, Hilal; Kemerli, Tansel; Sakin-Yilmazer, Melike; Guven, Gonul; Ozdestan, Ozgul; Uren, Ali; Kaymak-Ertekin, Figen

2012-10-01

Effects of baking method and temperature on surface browning and acrylamide concentration of cookies were investigated. Cookies were baked in natural and forced convection and steam-assisted hybrid ovens at 165, 180, and 195 °C and at different times. For all oven types, the acrlyamide concentration and surface color of cookies increased with increasing baking temperature. Significant correlation was observed between acrylamide formation and browning index, BI, which was calculated from Hunter L, a, and b color values, and it showed that the BI may be considered as a reliable indicator of acrylamide concentration in cookies. Acrylamide formation and browning index in cookies were considered as the first-order reaction kinetics and the reaction rate constants, k, were in the range of 0.023 to 0.077 (min(-1) ) and 0.019 to 0.063 (min(-1) ), respectively. The effect of baking temperature on surface color and acrylamide concentration followed the Arrhenius type of equation, with activation energies for acrylamide concentration as 6.87 to 27.84 kJ/mol; for BI value as 19.54 to 35.36 kJ/mol, for all oven types. Steam-assisted baking resulted in lower acrylamide concentration at 165 °C baking temperature and lower surface color for all temperatures. Steam-assisted baking is recommended as a healthy way of cooking providing the reduction of harmful compounds such as acrylamide for bakery goods, at a minimal level, while keeping the physical quality. The kinetics of acrylamide formation and browning of cookies will possibly allow definition of optimum baking temperatures and times at convectional and steam-assisted baking ovens. The kinetic model can be used by developing baking programs that can automatically control especially a new home-scale steam-assisted hybrid oven producing healthy products, for the use of domestic consumers. © 2012 Institute of Food Technologists®

EASI - EQUILIBRIUM AIR SHOCK INTERFERENCE

NASA Technical Reports Server (NTRS)

Glass, C. E.

1994-01-01

New research on hypersonic vehicles, such as the National Aero-Space Plane (NASP), has raised concerns about the effects of shock-wave interference on various structural components of the craft. State-of-the-art aerothermal analysis software is inadequate to predict local flow and heat flux in areas of extremely high heat transfer, such as the surface impingement of an Edney-type supersonic jet. EASI revives and updates older computational methods for calculating inviscid flow field and maximum heating from shock wave interference. The program expands these methods to solve problems involving the six shock-wave interference patterns on a two-dimensional cylindrical leading edge with an equilibrium chemically reacting gas mixture (representing, for example, the scramjet cowl of the NASP). The inclusion of gas chemistry allows for a more accurate prediction of the maximum pressure and heating loads by accounting for the effects of high temperature on the air mixture. Caloric imperfections and specie dissociation of high-temperature air cause shock-wave angles, flow deflection angles, and thermodynamic properties to differ from those calculated by a calorically perfect gas model. EASI contains pressure- and temperature-dependent thermodynamic and transport properties to determine heating rates, and uses either a calorically perfect air model or an 11-specie, 7-reaction reacting air model at equilibrium with temperatures up to 15,000 K for the inviscid flowfield calculations. EASI solves the flow field and the associated maximum surface pressure and heat flux for the six common types of shock wave interference. Depending on the type of interference, the program solves for shock-wave/boundary-layer interaction, expansion-fan/boundary-layer interaction, attaching shear layer or supersonic jet impingement. Heat flux predictions require a knowledge (from experimental data or relevant calculations) of a pertinent length scale of the interaction. Output files contain flow-field information for the various shock-wave interference patterns and their associated maximum surface pressure and heat flux predictions. EASI is written in FORTRAN 77 for a DEC VAX 8500 series computer using the VAX/VMS operating system, and requires 75K of memory. The program is available on a 9-track 1600 BPI magnetic tape in DEC VAX BACKUP format. EASI was developed in 1989. DEC, VAX, and VMS are registered trademarks of the Digital Equipment Corporation.

F-16XL ship #1 - CAWAP boundary layer hot film, left wing

NASA Technical Reports Server (NTRS)

1996-01-01

This photo shows the boundary layer hot film on the left wing of NASA's single-seat F-16XL (ship #1) used for the Cranked-Arrow Wing Aerodynamic Project (CAWAP) at Dryden Flight Research Center, Edwards, California. Hot film is used to measure temperature changes on a surface. The modified airplane features a delta 'cranked-arrow' wing with strips of tubing along the leading edge to the trailing edge to sense static on the wing and obtain pressure distribution data. The right wing receives data on pressure distribution and the left wing has three types of instrumentation - preston tubes to measure local skin friction, boundary layer rakes to measure boundary layer profiles (the layer where the air interacts with the surfaces of a moving aircraft), and hot films to determine boundary layer transition locations. The program also gathered aero data on two wing planforms for NASA's High Speed Research Program. The first flight of CAWAP occurred on November 21, 1995, and the test program ended in April 1996.

Simulation and measurement of nanometer-scale resistivity of copper films for interconnect applications

NASA Astrophysics Data System (ADS)

Yarimbiyik, Arif Emre

2007-12-01

A highly versatile simulation program is developed and used to examine how the resistivity of thin metal films and lines increases as their dimensions approach and become smaller than the mean fee path of electrons in metals such as copper (size effect). The simulation program: (1) provides a more accurate calculation of surface scattering effects than that obtained from the usual formulation of Fuchs' theory, (2) calculates grain-boundary effects that are consistent with the theory of Mayadas and Shatzkes, (3) includes the effects of surface and grain-boundary scattering either separately or together, and (4) simulates the effect on resistivity if a surface of a film or line has a different value for the scattering parameter. The increase in resistivity with decreasing thickness of thin, evaporated copper films (approximately 10 nm to 150 nm thick) was determined from sheet resistance and film thickness measurements. Good agreement between the experimental results with those of the simulation program was obtained when the measured mean grain sizes were used by the simulation program. The mean of the grain sizes tend to decrease with decreasing film thickness and thereby increase the impact of grain-boundary scattering on the effective resistivity of the film. Estimates of the mean grain size for each film were determined from using, in combination, the electron backscatter diffraction (EBSD) and the X-ray diffraction (XRD) methods. With values for the measured change in sheet resistance with temperature of these films, it is shown that measurements of the electrical film thickness, using Matthiessen's rule, agreed to within 3 nm of the physical measurements (profilometer) of these films. Hence, Matthiessen's rule can continue to be used to measure the thickness of a copper film and, by inference, the cross-sectional area of a copper line for dimensions well below the mean free path of electrons in copper at room temperature (39 nm).

Formation of Germa-ketenimine on the Ge(100) Surface by Adsorption of tert-Butyl Isocyanide.

PubMed

Shong, Bonggeun; Yoo, Jong Suk; Sandoval, Tania E; Bent, Stacey F

2017-06-28

Reactions of the (100) surfaces of Ge and Si with organic molecules have been generally understood within the concept of "dimers" formed by the 2 × 1 surface reconstruction. In this work, the adsorption of tert-butyl isocyanide on the Ge(100)-2 × 1 surface at large exposures is investigated under ultrahigh vacuum conditions. A combination of infrared spectroscopy, X-ray photoelectron spectroscopy, and temperature-programmed desorption experiments along with dispersion-corrected density functional theory calculations is used to determine the surface products. Upon adsorption of a dense monolayer of tert-butyl isocyanide, a product whose structure resembles a germa-ketenimine (N=C=Ge) with σ donation toward and π back-donation from the Ge(100) surface appears. Formation of this structure involves divalent-type surface Ge atoms that arise from cleavage of the Ge(100)-2 × 1 surface dimers. Our results reveal an unprecedented class of reactions of organic molecules at the Ge(100) surface.

Liquid oxygen liquid acquisition device bubble point tests with high pressure lox at elevated temperatures

NASA Astrophysics Data System (ADS)

Jurns, J. M.; Hartwig, J. W.

2012-04-01

When transferring propellant in space, it is most efficient to transfer single phase liquid from a propellant tank to an engine. In earth's gravity field or under acceleration, propellant transfer is fairly simple. However, in low gravity, withdrawing single-phase fluid becomes a challenge. A variety of propellant management devices (PMDs) are used to ensure single-phase flow. One type of PMD, a liquid acquisition device (LAD) takes advantage of capillary flow and surface tension to acquire liquid. The present work reports on testing with liquid oxygen (LOX) at elevated pressures (and thus temperatures) (maximum pressure 1724 kPa and maximum temperature 122 K) as part of NASA's continuing cryogenic LAD development program. These tests evaluate LAD performance for LOX stored in higher pressure vessels that may be used in propellant systems using pressure fed engines. Test data shows a significant drop in LAD bubble point values at higher liquid temperatures, consistent with lower liquid surface tension at those temperatures. Test data also indicates that there are no first order effects of helium solubility in LOX on LAD bubble point prediction. Test results here extend the range of data for LOX fluid conditions, and provide insight into factors affecting predicting LAD bubble point pressures.

Temperature dependent evolution of wrinkled single-crystal silicon ribbons on shape memory polymers.

PubMed

Wang, Yu; Yu, Kai; Qi, H Jerry; Xiao, Jianliang

2017-10-25

Shape memory polymers (SMPs) can remember two or more distinct shapes, and thus can have a lot of potential applications. This paper presents combined experimental and theoretical studies on the wrinkling of single-crystal Si ribbons on SMPs and the temperature dependent evolution. Using the shape memory effect of heat responsive SMPs, this study provides a method to build wavy forms of single-crystal silicon thin films on top of SMP substrates. Silicon ribbons obtained from a Si-on-insulator (SOI) wafer are released and transferred onto the surface of programmed SMPs. Then such bilayer systems are recovered at different temperatures, yielding well-defined, wavy profiles of Si ribbons. The wavy profiles are shown to evolve with time, and the evolution behavior strongly depends on the recovery temperature. At relatively low recovery temperatures, both wrinkle wavelength and amplitude increase with time as evolution progresses. Finite element analysis (FEA) accounting for the thermomechanical behavior of SMPs is conducted to study the wrinkling of Si ribbons on SMPs, which shows good agreement with experiment. Merging of wrinkles is observed in FEA, which could explain the increase of wrinkle wavelength observed in the experiment. This study can have important implications for smart stretchable electronics, wrinkling mechanics, stimuli-responsive surface engineering, and advanced manufacturing.

Satellite Validation: A Project to Create a Data-Logging System to Monitor Lake Tahoe

NASA Technical Reports Server (NTRS)

Roy, Rudy A.

2005-01-01

Flying aboard the satellite Terra, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is an imaging instrument used to acquire detailed maps of Earth's surface temperature, elevation, emissivity, and reflectance. An automated site consisting of four buoys was established 6 years ago at Lake Tahoe for the validation of ASTERS thermal infrared data. Using Campbell CR23X Dataloggers, a replacement system to be deployed on a buoy was designed and constructed for the measurement of the lake's temperature profile, surrounding air temperature, humidity, wind direction and speed, net radiation, and surface skin temperature. Each Campbell Datalogger has been programmed to control, power, and monitor 14 different temperature sensors, a JPL-built radiometer, and an RM Young 32500 meteorological station. The logger communicates with the radiometer and meteorological station through a Campbell SDM-SIO4 RS232 serial interface, sending polling commands, and receiving filtered data back from the sensors. This data is then cataloged and sent back across a cellular modem network every hour to JPL. Each instrument is wired via a panel constructed with 18 individual plugs that allow for simple installation and expansion. Data sent back from the system are analyzed at JPL, where they are used to calibrate ASTER data.

Liquid Oxygen Liquid Acquisition Device Bubble Point Tests with High Pressure LOX at Elevated Temperatures

NASA Technical Reports Server (NTRS)

Jurns, John M.; Hartwig, Jason W.

2011-01-01

When transferring propellant in space, it is most efficient to transfer single phase liquid from a propellant tank to an engine. In earth s gravity field or under acceleration, propellant transfer is fairly simple. However, in low gravity, withdrawing single-phase fluid becomes a challenge. A variety of propellant management devices (PMD) are used to ensure single-phase flow. One type of PMD, a liquid acquisition device (LAD) takes advantage of capillary flow and surface tension to acquire liquid. The present work reports on testing with liquid oxygen (LOX) at elevated pressures (and thus temperatures) (maximum pressure 1724 kPa and maximum temperature 122K) as part of NASA s continuing cryogenic LAD development program. These tests evaluate LAD performance for LOX stored in higher pressure vessels that may be used in propellant systems using pressure fed engines. Test data shows a significant drop in LAD bubble point values at higher liquid temperatures, consistent with lower liquid surface tension at those temperatures. Test data also indicates that there are no first order effects of helium solubility in LOX on LAD bubble point prediction. Test results here extend the range of data for LOX fluid conditions, and provide insight into factors affecting predicting LAD bubble point pressures.

Effects of silver and group 2 fluorides addition to plasma sprayed chromium carbide high temperature solid lubricant for foil gas bearing to 650 deg C

NASA Technical Reports Server (NTRS)

Wagner, R. C.; Sliney, H. E.

1984-01-01

A new self-lubricating coating composition of nickel aluminide-bonded chromium carbide formulated with silver and Group II fluorides was developed in a research program on high temperature solid lubricants. One of the proposed applications for this new coating composition is as a wide temperature spectrum solid lubricant for complaint foil gas bearings. Friction and wear properties were obtained using a foil gas bearing start/stop apparatus at temperatures from 25 to 650 C. The journals were Inconel 718. Some were coated with the plasma sprayed experimental coating, others with unmodified nickel aluminide/chromium carbide as a baseline for comparison. The addtitional components were provided to assist in achieving low friction over the temperature range of interest. Uncoated, preoxidized Inconel X-750 foil bearings were operated against these surfaces. The foils were subjected to repeated start/stop cycles under a 14-kPa (2-psi) bearing unit loading. Sliding contact occurred during lift-off and coastdown at surface velocities less than 6 m/s (3000 rpm). Testing continued until 9000 start/stop cycles were accumulated or until a rise in starting torque indicated the journal/bearing had failed. Comparison in coating performance as well as discussions of their properties and methods of application are given.

Ethanol surface chemistry on MBE-grown GaN(0001), GaOx/GaN(0001), and Ga2O3(2 \\xAF 01 )

NASA Astrophysics Data System (ADS)

Kollmannsberger, Sebastian L.; Walenta, Constantin A.; Winnerl, Andrea; Knoller, Fabian; Pereira, Rui N.; Tschurl, Martin; Stutzmann, Martin; Heiz, Ueli

2017-09-01

In this work, ethanol is used as a chemical probe to study the passivation of molecular beam epitaxy-grown GaN(0001) by surface oxidation. With a high degree of oxidation, no reaction from ethanol to acetaldehyde in temperature-programmed desorption experiments is observed. The acetaldehyde formation is attributed to a mechanism based on α -H abstraction from the dissociatively bound alcohol molecule. The reactivity is related to negatively charged surface states, which are removed upon oxidation of the GaN(0001) surface. This is compared with the Ga2O3(2 ¯ 01 ) single crystal surface, which is found to be inert for the acetaldehyde production. These results offer a toolbox to explore the surface chemistry of nitrides and oxynitrides on an atomic scale and relate their intrinsic activity to systems under ambient atmosphere.

Ethanol surface chemistry on MBE-grown GaN(0001), GaOx/GaN(0001), and Ga2O3(2¯01).

PubMed

Kollmannsberger, Sebastian L; Walenta, Constantin A; Winnerl, Andrea; Knoller, Fabian; Pereira, Rui N; Tschurl, Martin; Stutzmann, Martin; Heiz, Ueli

2017-09-28

In this work, ethanol is used as a chemical probe to study the passivation of molecular beam epitaxy-grown GaN(0001) by surface oxidation. With a high degree of oxidation, no reaction from ethanol to acetaldehyde in temperature-programmed desorption experiments is observed. The acetaldehyde formation is attributed to a mechanism based on α-H abstraction from the dissociatively bound alcohol molecule. The reactivity is related to negatively charged surface states, which are removed upon oxidation of the GaN(0001) surface. This is compared with the Ga 2 O 3 (2¯01) single crystal surface, which is found to be inert for the acetaldehyde production. These results offer a toolbox to explore the surface chemistry of nitrides and oxynitrides on an atomic scale and relate their intrinsic activity to systems under ambient atmosphere.

Differences between near-surface equivalent temperature and temperature trends for the Eastern United States. Equivalent temperature as an alternative measure of heat content

USGS Publications Warehouse

Davey, C.A.; Pielke, R.A.; Gallo, K.P.

2006-01-01

There is currently much attention being given to the observed increase in near-surface air temperatures during the last century. The proper investigation of heating trends, however, requires that we include surface heat content to monitor this aspect of the climate system. Changes in heat content of the Earth's climate are not fully described by temperature alone. Moist enthalpy or, alternatively, equivalent temperature, is more sensitive to surface vegetation properties than is air temperature and therefore more accurately depicts surface heating trends. The microclimates evident at many surface observation sites highlight the influence of land surface characteristics on local surface heating trends. Temperature and equivalent temperature trend differences from 1982-1997 are examined for surface sites in the Eastern U.S. Overall trend differences at the surface indicate equivalent temperature trends are relatively warmer than temperature trends in the Eastern U.S. Seasonally, equivalent temperature trends are relatively warmer than temperature trends in winter and are relatively cooler in the fall. These patterns, however, vary widely from site to site, so local microclimate is very important. ?? 2006 Elsevier B.V. All rights reserved.

An Examination of Intertidal Temperatures Through Remotely Sensed Satellite Observations

NASA Astrophysics Data System (ADS)

Lakshmi, V.

2010-12-01

MODIS Aqua and Terra satellites produce both land surface temperatures and sea surface temperatures using calibrated algorithms. In this study, the land surface temperatures were retrieved during clear-sky (non-cloudy) conditions at a 1 km2 resolution (overpass time at 10:30 am) whereas the sea surface temperatures are also retrieved during clear-sky conditions at approximately 4 km resolution (overpass time at 1:30 pm). The purpose of this research was to examine remotely sensed sea surface (SST), intertidal (IST), and land surface temperatures (LST), in conjunction with observed in situ mussel body temperatures, as well as associated weather and tidal data. In Strawberry Hill, Oregon, it was determined that intertidal surface temperatures are similar to but distinctly different from land surface temperatures although influenced by sea surface temperatures. The air temperature and differential heating throughout the day, as well as location in relation to the shore, can greatly influence the remotely sensed surface temperatures. Therefore, remotely sensed satellite data is a very useful tool in examining intertidal temperatures for regional climatic changes over long time periods and may eventually help researchers forecast expected climate changes and help determine associated biological implications.

Computer modeling of a hot filament diamond deposition reactor

NASA Technical Reports Server (NTRS)

Kuczmarski, Maria A.; Washlock, Paul A.; Angus, John C.

1991-01-01

A commercial fluid mechanics program, FLUENT, has been applied to the modeling of a hot-filament diamond deposition reactor. Streamlines and contours of constant temperature and species concentrations are obtained for practical reactor geometries and conditions. The modeling is presently restricted to two-dimensional simulations and to a chemical mechanism of ten independent homogeneous and surface reactions. Comparisons are made between predicted power consumption, substrate temperature, and concentrations of atomic hydrogen and methyl-radical with values taken from the literature. The results to date indicate that the modeling can aid in the rational design and analysis of practical reactor configurations.

Acetone Chemistry on Oxidized and Reduced TiO 2(110)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henderson, Michael A

2004-12-09

The chemistry of acetone on the oxidized and reduced surfaces of TiO 2(110) was examined using temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS). The reduced surface was prepared with about 7% oxygen vacancy sites by annealing in ultrahigh vacuum (UHV) at 850 K, and the oxidized surface was prepared by exposure of the reduced surface to molecular oxygen at 95 K followed by heating the surface to a variety of temperatures between 200 and 500 K. Acetone adsorbs molecularly on the reduced surface with no evidence for either decomposition or preferential binding at vacancy sites.more » Based on HREELS, the majority of acetone molecules adsorbed in an η¹ configuration at Ti⁴⁺ sites through interaction of lone pair electrons on the carbonyl oxygen atom. Repulsive acetone-acetone interactions shift the desorption peak from 345 K at low coverage to 175 K as the first layer saturates with a coverage of ~ 1 ML. In contrast, about 7% of the acetone adlayer decomposes when the surface is pretreated with molecular oxygen. Acetate is among the detected decomposition products, but only comprises about 1/3rd of the amount of acetone decomposed and its yield depends on the temperature at which the O₂ exposed surface was preheated to prior to acetone adsorption. Aside from the small level of irreversible decomposition, about 0.25 ML of acetone is stabilized to 375 K by coadsorbed oxygen. These acetone species exhibit an HREELS spectrum unlike that of η¹-acetone or of any other species proposed to exist from the interaction of acetone with TiO₂ powders. Based on the presence of extensive ¹⁶O/¹⁸O exchange between acetone and coadsorbed oxygen in the 375 K acetone TPD state, it is proposed that a polymeric form of acetone forms on the TiO₂(110) surface through nucleophilic attack of oxygen on the carbonyl carbon atom of acetone, and is propagated to neighboring η¹-acetone molecules. This process is initiated at temperatures as low as 135 K based on HREELS. Although the dominant thermal pathway of this surface species is to liberate acetone in UHV, it may be a key intermediate in acetone thermal and photolytic chemistry on TiO₂ surfaces.« less

The Effects of Temperature and Oxidation on Deuterium Retention in Solid and Liquid Lithium Films on Molybdenum Plasma-Facing Components

NASA Astrophysics Data System (ADS)

Capece, Angela

2014-10-01

Liquid metal plasma-facing components (PFCs) enable in-situ renewal of the surface, thereby offering a solution to neutron damage, erosion, and thermal fatigue experienced by solid PFCs. Lithium in particular has a high chemical affinity for hydrogen, which has resulted in reduced recycling and enhanced plasma performance on many fusion devices including TFTR, T11-M, FTU, CDX-U, LTX, TJ-II, and NSTX. A key component to the improvement in plasma performance is deuterium retention in Li; however, this process is not well understood in the complex tokamak environment. Recent surface science experiments conducted at the Princeton Plasma Physics Laboratory have used electron spectroscopy and temperature programmed desorption to understand the mechanisms for D retention in Li coatings on Mo substrates. The experiments were designed to give monolayer-control of Li films and were conducted in ultrahigh vacuum under controlled environments. An electron cyclotron resonance plasma source was used to deliver a beam of deuterium ions to the surface over a range of ion energies. Our work shows that D is retained as LiD in metallic Li films. However, when oxygen is present in the film, either by diffusion from the subsurface at high temperature or as a contaminant during the deposition process, Li oxides are formed that retain D as LiOD. Experiments indicate that LiD is more thermally stable than LiOD, which decomposes to liberate D2 gas and D2O at temperatures 100 K lower than the LiD decomposition temperature. Other experiments show how D retention varies with substrate temperature to provide insight into the differences between solid and liquid lithium films. This work was supported by DOE Contract No. DE AC02-09CH11466.

Coverage-Dependent Anchoring of 4,4'-Biphenyl Dicarboxylic Acid to CoO(111) Thin Films.

PubMed

Mohr, Susanne; Schmitt, Tobias; Döpper, Tibor; Xiang, Feifei; Schwarz, Matthias; Görling, Andreas; Schneider, M Alexander; Libuda, Jörg

2017-05-02

We investigated the adsorption behavior of 4,4'-biphenhyl dicarboxylic acid (BDA) on well-ordered CoO(111) films grown on Ir(100) as a function of coverage and temperature using time-resolved and temperature-programmed infrared reflection absorption spectroscopy (TR-IRAS, TP-IRAS) in combination with density functional theory (DFT) and scanning tunneling microscopy (STM) under ultrahigh vacuum (UHV) conditions. To compare the binding behavior of BDA as a function of the oxide film thickness, three different CoO(111) film thicknesses were explored: films of about 20 bilayers (BLs) (approximately 5 nm), 2 BLs, and 1 BL. The two carboxylic acid groups of BDA offer two potential anchoring points to the oxide surface. At 150 K, intact BDA adsorbs on 20 BL thick oxide films in planar geometry with the phenyl rings aligned parallel to the surface. With decreasing oxide film thickness, we observe an increasing tendency for deprotonation and the formation of flat-lying BDA molecules anchored as dicarboxylates. After saturation of the first monolayer, intact BDA multilayers grow with molecules aligned parallel to the surface. The BDA multilayer desorbs at around 360 K. Completely different growth behavior is observed if BDA is deposited above the multilayer desorption temperature. Initially, doubly deprotonated dicarboxylates are formed by adopting a flat-lying orientation. With increasing exposure, however, the adsorbate layer transforms into upright standing monocarboxylates. A sharp OH stretching band (3584 cm -1 ) and a blue-shifted CO stretching band (1759 cm -1 ) indicate weakly interacting apical carboxylic acid groups at the vacuum interface. The anchored monocarboxylate phase slowly desorbs in a temperature range of up to 470 K. At higher temperature, a flat-lying doubly deprotonated BDA is formed, which desorbs and decomposes in a temperature range of up to 600 K.

An Overview of High Temperature Seal Development and Testing Capabilities at the NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Demange, Jeffrey J.; Taylor, Shawn C.; Dunlap, Patrick H.; Steinetz, Bruce M.; Finkbeiner, Joshua R.; Proctor, Margaret P.

2014-01-01

The NASA Glenn Research Center (GRC), partnering with the University of Toledo, has a long history of developing and testing seal technologies for high-temperature applications. The GRC Seals Team has conducted research and development on high-temperature seal technologies for applications including advanced propulsion systems, thermal protection systems (airframe and control surface thermal seals), high-temperature preloading technologies, and other extreme-environment seal applications. The team has supported several high-profile projects over the past 30 years and has partnered with numerous organizations, including other government entities, academic institutions, and private organizations. Some of these projects have included the National Aerospace Space Plane (NASP), Space Shuttle Space Transport System (STS), the Multi-Purpose Crew Vehicle (MPCV), and the Dream Chaser Space Transportation System, as well as several high-speed vehicle programs for other government organizations. As part of the support for these programs, NASA GRC has developed unique seal-specific test facilities that permit evaluations and screening exercises in relevant environments. The team has also embarked on developing high-temperature preloaders to help maintain seal functionality in extreme environments. This paper highlights several propulsion-related projects that the NASA GRC Seals Team has supported over the past several years and will provide an overview of existing testing capabilities

ISS and TPD study of the adsorption and interaction of CO and H2 on polycrystalline Pt

NASA Technical Reports Server (NTRS)

Melendez, Orlando; Hoflund, Gar B.; Schryer, David R.

1990-01-01

The adsorption and interaction of CO and H2 on polycrystalline Pt has been studied using ion scattering spectroscopy (ISS) and temperature programmed desorption (TPD). The ISS results indicate that the initial CO adsorption on Pt takes place very rapidly and saturates the Pt surface with coverage close to a monolayer. ISS also shows that the CO molecules adsorb at an angular orientation from the surface normal and perhaps parallel to the surface. A TPD spectrum obtained after coadsorbing C-12 O-16 and C-13 O-18 on Pt shows no isotopic mixing, which is indicative of molecular CO adsorption. TPD spectra obtained after coadsorbing H2 and CO on polycrystalline Pt provides evidence for the formation of a CO-H surface species.

Inventory of File nam.t00z.smartpr12.tm00.grib2

Science.gov Websites

Temperature [K] 002 surface DPT 12 hour fcst Dew Point Temperature [K] 003 surface SPFH 12 hour fcst Specific 11 hour fcst Temperature [K] 032 surface TMP 10 hour fcst Temperature [K] 033 surface DPT 11 hour fcst Dew Point Temperature [K] 034 surface DPT 10 hour fcst Dew Point Temperature [K] 035 surface TMAX

Inventory of File nam.t00z.smartak12.tm00.grib2

Science.gov Websites

Temperature [K] 002 surface DPT 12 hour fcst Dew Point Temperature [K] 003 surface SPFH 12 hour fcst Specific 11 hour fcst Temperature [K] 032 surface TMP 10 hour fcst Temperature [K] 033 surface DPT 11 hour fcst Dew Point Temperature [K] 034 surface DPT 10 hour fcst Dew Point Temperature [K] 035 surface TMAX

Inventory of File nam.t00z.smarthi12.tm00.grib2

Science.gov Websites

Temperature [K] 002 surface DPT 12 hour fcst Dew Point Temperature [K] 003 surface SPFH 12 hour fcst Specific 11 hour fcst Temperature [K] 032 surface TMP 10 hour fcst Temperature [K] 033 surface DPT 11 hour fcst Dew Point Temperature [K] 034 surface DPT 10 hour fcst Dew Point Temperature [K] 035 surface TMAX

Inventory of File nam.t00z.smartconus03.tm00.grib2

Science.gov Websites

Temperature [K] 002 surface DPT 3 hour fcst Dew Point Temperature [K] 003 surface SPFH 3 hour fcst Specific Temperature [K] 026 surface TMP 1 hour fcst Temperature [K] 027 surface DPT 2 hour fcst Dew Point Temperature [K] 028 surface DPT 1 hour fcst Dew Point Temperature [K] 029 surface TMAX 0-3 hour acc Maximum

Inventory of File gfs.t06z.smartguam18.tm00.grib2

Science.gov Websites

Temperature [K] 002 surface DPT 18 hour fcst Dew Point Temperature [K] 003 surface SPFH 18 hour fcst Specific TMP 17 hour fcst Temperature [K] 022 surface TMP 16 hour fcst Temperature [K] 023 surface DPT 17 hour fcst Dew Point Temperature [K] 024 surface DPT 16 hour fcst Dew Point Temperature [K] 025 surface TMAX

HEATING 7. 1 user's manual

DOE Office of Scientific and Technical Information (OSTI.GOV)

Childs, K.W.

1991-07-01

HEATING is a FORTRAN program designed to solve steady-state and/or transient heat conduction problems in one-, two-, or three- dimensional Cartesian, cylindrical, or spherical coordinates. A model may include multiple materials, and the thermal conductivity, density, and specific heat of each material may be both time- and temperature-dependent. The thermal conductivity may be anisotropic. Materials may undergo change of phase. Thermal properties of materials may be input or may be extracted from a material properties library. Heating generation rates may be dependent on time, temperature, and position, and boundary temperatures may be time- and position-dependent. The boundary conditions, which maymore » be surface-to-boundary or surface-to-surface, may be specified temperatures or any combination of prescribed heat flux, forced convection, natural convection, and radiation. The boundary condition parameters may be time- and/or temperature-dependent. General graybody radiation problems may be modeled with user-defined factors for radiant exchange. The mesh spacing may be variable along each axis. HEATING is variably dimensioned and utilizes free-form input. Three steady-state solution techniques are available: point-successive-overrelaxation iterative method with extrapolation, direct-solution (for one-dimensional or two-dimensional problems), and conjugate gradient. Transient problems may be solved using one of several finite-difference schemes: Crank-Nicolson implicit, Classical Implicit Procedure (CIP), Classical Explicit Procedure (CEP), or Levy explicit method (which for some circumstances allows a time step greater than the CEP stability criterion). The solution of the system of equations arising from the implicit techniques is accomplished by point-successive-overrelaxation iteration and includes procedures to estimate the optimum acceleration parameter.« less

PERSPECTIVE Working towards a community-wide understanding of satellite skin temperature observations

NASA Astrophysics Data System (ADS)

Shreve, Cheney

2010-12-01

With more than sixty free and publicly available high-quality datasets, including ecosystem variables, radiation budget variables, and land cover products, the MODIS instrument and the MODIS scientific team have contributed significantly to scientific investigations of ecosystems across the globe. The MODIS instrument, launched in December 1999, has 36 spectral bands, a viewing swath of 2330 km, and acquires data at 250 m, 500 m, and 1000 m spatial resolution every one to two days. Radiation budget variables include surface reflectance, skin temperature, emissivity, and albedo, to list a few. Ecosystem variables include several vegetation indices and productivity measures. Land cover characteristics encompass land cover classifications as well as model parameters and vegetation classifications. Many of these products are instrumental in constraining global climate models and climate change studies, as well as monitoring events such as the recent flooding in Pakistan, the unprecedented oil spill in the Gulf of Mexico, or phytoplankton bloom in the Barents Sea. While product validation efforts by the MODIS scientific team are both vigorous and continually improving, validation is unquestionably one of the most difficult tasks when dealing with remotely derived datasets, especially at the global scale. The quality and availability of MODIS data have led to widespread usage in the scientific community that has further contributed to validation and development of the MODIS products. In their recent paper entitled 'Land surface skin temperature climatology: benefitting from the strengths of satellite observations', Jin and Dickinson review the scientific theory behind, and demonstrate application of, a MODIS temperature product: surface skin temperature. Utilizing datasets from the Global Historical Climatological Network (GHCN), daily skin and air temperature from the Atmospheric Radiation Measurement (ARM) program, and MODIS products (skin temperature, albedo, land cover, water vapor, cloud cover), they show that skin temperature is clearly a different physical parameter from air temperature and varies from air temperature in magnitude, response to atmospheric conditions, and diurnal phase. Although the accuracy of skin temperature (Tskin) algorithms has improved to within 0.5-1°C for field measurements and clear-sky satellite observations (Becker and Li 1995, Goetz et al 1995, Wan and Dozier 1996), general confusion regarding the physical definition of 'surface temperature' and how it can be used for climate studies has persisted throughout the scientific community and limited the applications of these data (Jin and Dickinson 2010). For example, satellite sea surface temperature was used as evidence of global climate change instead of skin temperature in the IPCC 2001 and 2007 reports (Jin and Dickinson 2010). This work provides clarity in the theoretical definition of temperature variables, demonstrates the difference between air and skin temperature, and aids the understanding of the MODIS Tskin product, which could be very beneficial for future climate studies. As outlined by Jin and Dickinson, 'surface temperature' is a vague term commonly used in reference to air temperature, aerodynamic temperature, and skin temperature. Air temperature (Tair), or thermodynamic temperature, is measured by an in situ instrument usually 1.5-2 m above the ground. Aerodynamic temperature (Taero) refers to the temperature at the height of the roughness length of heat. Satellite derived skin temperature (Tskin) is the radiometric temperature derived from the inverse of Planck's function. While these different temperature variables are typically correlated, they differ as a result of environmental conditions (e.g. land cover and sky conditions; Jin and Dickinson 2010). With an extensive network of Tair measurements, some have questioned the benefits of using Tskin at all (Peterson et al 1997, 1998). Tskin and Tair can vary depending on land cover or sky conditions and variations may be large, e.g., for sparsely vegetated areas where net radiation is largely balanced by sensible heat flux (Hall et al 1992, Sun and Mahrt 1995, Jin et al 1997). Tskin can be higher than Taero at midday and lower at night (Sun and Mahrt 1995) and some models use Taero to approximate surface radiative temperature (Hubband and Monteith 1986). One of the strengths of the MODIS instrument is the simultaneous collection of surface and atmospheric conditions. By incorporating a range of MODIS variables in their comparison to Tskin, the authors examine the relationship of Tskin to atmospheric and surface conditions. Results from their global evaluation of Tskin highlight its variability on an inter-annual basis, its variation with solar zenith angle, and diurnal variations, which are not achievable with Tair measurements. Comparison with land cover type illustrates the seasonality of Tskin for different land covers. Comparison with the enhanced vegetation index (EVI) suggests more vegetation reduces skin temperature. Using the MODIS albedo, they demonstrate a clear relationship between yearly averaged Tskin and land surface albedo. Lastly, their examination of water vapor and cloud cover in comparison to Tskin suggests similar seasonality between these two variables. The MODIS Tskin product is not without uncertainty; retrieving Tskin requires a calculation of radiative transfer to account for atmospheric emission and molecular absorption, which is time and resource intensive (Jin and Dickinson 2010). Additionally, surface emissivity, instrument noise, and view angle geometry contribute to error in Tskin estimations (Jin and Dickinson 2010). The transparency of the scientific theory underlying this work, and the clear demonstration of the distinction between temperature measures on varying scales, demonstrates the usefulness of Tskin despite the uncertainties. Perhaps equally as important is the tone; in a time when the controversy surrounding climate change is peaking and the very ethics of the scientific community are being questioned, it is more critical than ever to be transparent in one's work and to assist the scientific community in understanding the tools we have available to us for investigating climate change. References Becker F and Li Z-L 1995 Surface temperature and emissivity at different scales: definition, measurement and related problems Remote Sensing Rev. 12 225-53 Goetz S J, Halthore R, Hall F G and Markham B L 1995 Surface temperature retrieval in a temperate grassland with multi-resolution sensors J. Geophys. Res. Atmos. 100 25397-410 Hall F G, Huemmrich K F, Goetz P J, Sellers P J and Nickeson J E 1992 Satellite remote sensing of the surface energy balance: success, failures and unresolved issues in FIFE J. Geophys. Res. Atmos. 97 19061-90 Jin M and Dickinson R E 2010 Land surface skin temperature climatology: benefitting from the strengths of satellite observations Environ. Res. Lett. 5 044004 Jin M, Dickinson R E and Vogelmann A M 1997 A comparison of CCM2/BATS skin temperature and surface-air temperature with satellite and surface observations J. Climate 10 1505-24 Hubband N D S and Monteith J L 1986 Radiative surface temperature and energy balance of a wheat canopy Boundary Layer Meteorol. 36 107-16 Peterson T C and Vose R S 1997 An overview of the Global Historical Climatology Network temperature data base Bull. Am. Meteorol. Soc. 78 2837-49 Peterson T C, Karl T R, Jamason P F, Knight R and Easterling D R 1998 The first difference method: maximizing station density for the calculation of long-term global temperature change J. Geophys. Res. Atmos. 103 25967-74 Sun J and Mahrt L 1995 Determination of surface fluxes from the surface radiative temperature Atmos. Sci. 52 1096-106 Wan Z and Dozier J 1996 A generalized split-window algorithm for retrieving land-surface temperature from space IEEE Trans. Geosci. Remote Sensing 34 892-905

Textural evolution of partially-molten planetary materials in microgravity

NASA Technical Reports Server (NTRS)

Watson, E. B.

1987-01-01

Recent Earth-based experiments examining the textural evolution of partially-molten rocks have revealed two important ways in which surface energy considerations affect magma. An initial experimental program addressing surface-energy effects on partially-molten materials in microgravity would involve simple, isothermal treatment of natural samples (meteorites, perioditic komatiite) at preselected temperatures in the melting range. Textural evolution would be assessed by time studies in which the only experiment variable would be run duration. Textural characterization of each sample would be done by quenching, recover, and sectioning for generally later, computer-aided interpretation of features.

Shaded-Color Picture Generation of Computer-Defined Arbitrary Shapes

NASA Technical Reports Server (NTRS)

Cozzolongo, J. V.; Hermstad, D. L.; Mccoy, D. S.; Clark, J.

1986-01-01

SHADE computer program generates realistic color-shaded pictures from computer-defined arbitrary shapes. Objects defined for computer representation displayed as smooth, color-shaded surfaces, including varying degrees of transparency. Results also used for presentation of computational results. By performing color mapping, SHADE colors model surface to display analysis results as pressures, stresses, and temperatures. NASA has used SHADE extensively in sign and analysis of high-performance aircraft. Industry should find applications for SHADE in computer-aided design and computer-aided manufacturing. SHADE written in VAX FORTRAN and MACRO Assembler for either interactive or batch execution.

ALMA Thermal Mapping of Ceres – Search for Subsurface Water Ice

NASA Astrophysics Data System (ADS)

Moullet, Arielle; Li, Jian-Yang; Titus, Timothy N.; Sykes, Mark V.; Hsieh, Henry H.

2018-06-01

Spectroscopic observations of the surface of Ceres by Dawn have demonstrated that hydrated minerals are ubiquitous, but only few smaller sites are enriched with water ice. This is somewhat surprising as Ceres is believed to host a large amount a water in its interior.The possibility of inhomogeneous subsurface water distribution can be investigated by tracing thermal inertia distribution. To that effect, we mapped the temperature of Ceres using 1.3mm maps of the whole surface obtained with the Atacama Large Millimeter Array (ALMA) over three different epochs during one Ceres’ year. Assessing the thermal conditions at the depths probed by sub millimeter observations (a few cm below the surface, within the annual thermal skin depth) is critical to constrain the effective thermal inertia, and hence the status of subsurface water ice. We will present preliminary results in terms of temperature features and the corresponding thermal inertia derived based on comparisons from the KRC thermal model which has been extensively used for Mars. Initial analysis is consistent with the presence of near-surface high thermal inertia layer, presumably water ice, in the north polar region.This work is supported by the NASA Solar System Observations Program NNX15AE02G.

Factors Influencing NO2 Adsorption/Reduction on Microporous Activated Carbon: Porosity vs. Surface Chemistry

PubMed Central

Ghouma, Imen; Limousy, Lionel; Bennici, Simona

2018-01-01

The textural properties and surface chemistry of different activated carbons, prepared by the chemical activation of olive stones, have been investigated in order to gain insight on the NO2 adsorption mechanism. The parent chemical activated carbon was prepared by the impregnation of olive stones in phosphoric acid followed by thermal carbonization. Then, the textural properties and surface chemistry were modified by chemical treatments including nitric acid, sodium hydroxide and/or a thermal treatment at 900 °C. The main properties of the parent and modified activated carbons were analyzed by N2-adsorption, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) techniques, in order to enlighten the modifications issued from the chemical and thermal treatments. The NO2 adsorption capacities of the different activated carbons were measured in fixed bed experiments under 500 ppmv NO2 concentrations at room temperature. Temperature programmed desorption (TPD) was applied after adsorption tests in order to quantify the amount of the physisorbed and chemisorbed NO2. The obtained results showed that the development of microporosity, the presence of oxygen-free sites, and the presence of basic surface groups are key factors for the efficient adsorption of NO2. PMID:29670008

Exploring the nonequilibrium reactivity of molecules with platinum(111)

NASA Astrophysics Data System (ADS)

Dewitt, Kristin Marie

Various aspects of the nonequilibrium reactivity of several, catalytically important, small molecules with Pt(111)were explored. The effect of alkali metal promotion on the thermal chemistry and photochemistry of CH4,N 2, and CO2 was studied. Dissociative sticking coefficients for methane and ethane were measured as a function of gas temperature ( Tg) and surface temperature (Ts) using effusive molecular beam and angle-integrated gas dosing methods. Coupled with physisorbed complex microcanonical unimolecular rate theory these measurements provide a predictive understanding for the kinetics of these C-H bond activation reactions, i.e. allowing us to predict the sticking coefficient of CH 4 and C2H6 for any combination of T s and Tg. Work function thermal programmed desorption was used to examine the correlation between surface structure and surface work function for CH3Br and CO2. Preliminary two-photon photoemission and broad-band infrared-visible sum frequency generation experiments introduce these nonlinear spectroscopy techniques to the arsenal of surface characterization techniques available in our group. All of the disparate components of this work are tied together by one overall theme, developing an improved molecular-level understanding of the reaction dynamics of catalysis.

Chemisorption studies of Pt/SnO2 catalysts

NASA Technical Reports Server (NTRS)

Brown, Kenneth G.; Ohorodnik, Susan K.; Vannorman, John D.; Schryer, Jacqueline; Upchurch, Billy T.; Schryer, David R.

1990-01-01

The low temperature CO oxidation catalysts that are being developed and tested at NASA-Langley are fairly unique in their ability to efficiently oxidize CO at low temperatures (approx. 303 K). The bulk of the reaction data that has been collected in the laboratory has been determined using plug flow reactors with a low mass of Pt/SnO2/SiO2 catalyst (approx. 0.1 g) and a modest flow rate (5 to 10 sc sm). The researchers have previously characterized the surface solely in terms of N2 BET surface areas. These surface areas have not been that indicative of reaction rate. Indeed, some of the formulations with high BET surface area have yielded lower reaction rates than those with lower BET surface areas. As a result researchers began a program of determining the chemisorption of the various species involved in the reaction; CO, O2 and CO2. Such a determination of will lead to a better understanding of the mechanism and overall kinetics of the reaction. The pulsed-reactor technique, initially described by Freel, is used to determine the amount of a particular molecule that is adsorbed on the catalyst. Since there is some reaction of CO with the surface to produce CO2, the pulsed reactor had to be coupled with a gas chromatograph in order to distinguish between the loss of CO that is due to adsorption by the surface and the loss that is due to reaction with the surface.

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Progress is reported on fundamental research in: crystal physics, reactions at metal surfaces, spectroscopy of ionic media, structure of metals, theory of alloying, physical properties, sintering, deformation of crystalline solids, x ray diffraction, metallurgy of superconducting materials, and electron microscope studies. Long-randge applied research studies were conducted for: zirconium metallurgy, materials compatibility, solid reactions, fuel element development, mechanical properties, non-destructive testing, and high-temperature materials. Reactor development support work was carried out for: gas-cooled reactor program, molten-salt reactor, high-flux isotope reactor, space-power program, thorium-utilization program, advanced-test reactor, Army Package Power Reactor, Enrico Fermi fast-breeder reactor, and water desalination program. Other programmore » activities, for which research was conducted, included: thermonuclear project, transuraniunn program, and post-irradiation examination laboratory. Separate abstracts were prepared for 30 sections of the report. (B.O.G.)« less

The Mars Microprobe Mission: Advanced Micro-Avionics for Exploration Surface

NASA Astrophysics Data System (ADS)

Blue, Randel

2000-01-01

The Mars Microprobe Mission is the second spacecraft developed as part of the New Millennium Program deep space missions. The objective of the Microprobe Project is to demonstrate the applicability of key technologies for future planetary missions by developing two probes for deployment on Mars. The probes are designed with a single stage entry, descent, and landing system and impact the Martian surface at speeds of approximately 200 meters per second. The microprobes are composed of two main sections, a forebody section that penetrates to a depth below the Martian surface of 0.5 to 2 meters, and an aftbody section that remains on the surface. Each probe system consists of a number of advanced technology components developed specifically for this mission. These include a non-erosive aeroshell for entry into. the atmosphere, a set of low temperature batteries to supply probe power, an advanced microcontroller to execute the mission sequence, collect the science data, and react to possible system fault conditions, a telecommunications subsystem implemented on a set of custom integrated circuits, and instruments designed to provide science measurements from above and below the Martian surface. All of the electronic components have been designed and fabricated to withstand the severe impact shock environment and to operate correctly at predicted temperatures below -100 C.

Determination of Yield and Flow Surfaces for Inconel 718 Under Axial-Torsional Loading at Temperatures Up to 649 C

NASA Technical Reports Server (NTRS)

Gil, Christopher M.

1998-01-01

An experimental program to determine flow surfaces has been established and implemented for solution annealed and aged IN718. The procedure involved subjecting tubular specimens to various ratios of axial-torsional stress at temperatures between 23 and 649 C and measuring strain with a biaxial extensometer. Each stress probe corresponds to a different direction in stress space, and unloading occurs when a 30 microstrain (1 micro eplison = 10(exp -6) mm/mm) offset is detected. This technique was used to map out yield loci in axial-torsional stress space. Flow surfaces were determined by post-processing the experimental data to determine the inelastic strain rate components. Surfaces of constant inelastic strain rate (SCISRS) and surfaces of constant inelastic power (SCIPS) were mapped out in the axial-shear stress plane. The von Mises yield criterion appeared to closely fit the initial loci for solutioned IN718 at 23 C. However, the initial loci for solutioned IN718 at 371 and 454 C, and all of the initial loci for aged IN718 were offset in the compression direction. Subsequent loci showed translation, distortion, and for the case of solutioned IN718, a slight cross effect. Aged IN718 showed significantly more hardening behavior than solutioned IN718.

ASTM E 1559 method for measuring material outgassing/deposition kinetics has applications to aerospace, electronics, and semiconductor industries

NASA Technical Reports Server (NTRS)

Garrett, J. W.; Glassford, A. P. M.; Steakley, J. M.

1994-01-01

The American Society for Testing and Materials has published a new standard test method for characterizing time and temperature-dependence of material outgassing kinetics and the deposition kinetics of outgassed species on surfaces at various temperatures. This new ASTM standard, E 1559(1), uses the quartz crystal microbalance (QCM) collection measurement approach. The test method was originally developed under a program sponsored by the United States Air Force Materials Laboratory (AFML) to create a standard test method for obtaining outgassing and deposition kinetics data for spacecraft materials. Standardization by ASTM recognizes that the method has applications beyond aerospace. In particular, the method will provide data of use to the electronics, semiconductor, and high vacuum industries. In ASTM E 1559 the material sample is held in vacuum in a temperature-controlled effusion cell, while its outgassing flux impinges on several QCM's which view the orifice of the effusion cell. Sample isothermal total mass loss (TML) is measured as a function of time from the mass collected on one of the QCM's which is cooled by liquid nitrogen, and the view factor from this QCM to the cell. The amount of outgassed volatile condensable material (VCM) on surfaces at higher temperatures is measured as a function of time during the isothermal outgassing test by controlling the temperatures of the remaining QCM's to selected values. The VCM on surfaces at temperatures in between those of the collector QCM's is determined at the end of the isothermal test by heating the QCM's at a controlled rate and measuring the mass loss from the end of the QCM's as a function of time and temperature. This reevaporation of the deposit collected on the QCM's is referred to as QCM thermogravimetric analysis. Isothermal outgassing and deposition rates can be determined by differentiating the isothermal TML and VCM data, respectively, while the evaporation rates of the species can be obtained as a function of temperature by differentiating the QCM thermogravimetric analysis data.

Inventory of File gfs.t06z.smartguam03.tm00.grib2

Science.gov Websites

Temperature [K] 002 surface DPT 3 hour fcst Dew Point Temperature [K] 003 surface SPFH 3 hour fcst Specific surface 4LFTX 3 hour fcst Best (4 layer) Lifted Index [K] 019 surface TMP 2 hour fcst Temperature [K] 020 surface TMP 1 hour fcst Temperature [K] 021 surface DPT 2 hour fcst Dew Point Temperature [K] 022 surface

Optical Fiber Strain Instrumentation for High Temperature Aerospace Structural Monitoring

NASA Technical Reports Server (NTRS)

Wang, A.

2002-01-01

The objective of the program is the development and laboratory demonstration of sensors based on silica optical fibers for measurement of high temperature strain for aerospace materials evaluations. A complete fiber strain sensor system based on white-light interferometry was designed and implemented. An experiment set-up was constructed to permit testing of strain measurement up to 850 C. The strain is created by bending an alumina cantilever beam to which is the fiber sensor is attached. The strain calibration is provided by the application of known beam deflections. To ensure the high temperature operation capability of the sensor, gold-coated single-mode fiber is used. Moreover, a new method of sensor surface attachment which permits accurate sensor gage length determination is also developed. Excellent results were obtained at temperatures up to 800-850 C.

Differential response of surface temperature and atmospheric temperature to the biogeophysical effects of deforestation

NASA Astrophysics Data System (ADS)

Winckler, J.; Reick, C. H.; Lejeune, Q.; Pongratz, J.

2017-12-01

Deforestation influences temperature locally by changing the water, energy and momentum balance. While most observation-based studies and some modeling studies focused on the effects on surface temperature, other studies focused on the effects on near-surface air temperature. However, these two variables may respond differently to deforestation because changes in albedo and surface roughness may alter the land-atmosphere coupling and thus the vertical temperature distribution. Thus it is unclear whether it is possible to compare studies that assess the impacts of deforestation on these two different variables. Here, we analyze the biogeophysical effects of global-scale deforestation in the climate model MPI-ESM separately for surface temperature, 2m-air temperature and temperature the lowest atmospheric model layer. We investigate why the response of these variables differs by isolating the effects of only changing surface albedo and only changing surface roughness and by separating effects that are induced at the location of deforestation (local effects) from effects that are induced by advection and changes in circulation (nonlocal effects). Concerning surface temperature, we find that the local effects of deforestation lead to a global mean warming which is overcompensated by the nonlocal effects (up to 0.1K local warming versus -0.3K nonlocal cooling). The surface warming in the local effects is largely driven by the change in surface roughness while the cooling in the nonlocal effects is largely driven by the change in surface albedo. The nonlocal effects are largely consistent across surface temperature, 2m-air temperature, and the temperature of the lowest atmospheric layer. However, the local effects strongly differ across the three considered variables. The local effects are strong for surface temperature, but substantially weaker in the 2m-air temperature and largely absent in the lowest atmospheric layer. We conclude that studies focusing on the deforestation effects on surface temperature should not be compared to studies focusing on the effects on air temperature. While the local effects on surface temperature are useful for model evaluation, they might be less relevant for local adaptation and mitigation than previously thought because they might largely be absent in the atmosphere.

Mid-Piacenzian sea surface temperature record from ODP Site 1115 in the western equatorial Pacific

USGS Publications Warehouse

Stoll, Danielle

2010-01-01

Planktic foraminifer assemblages and alkenone unsaturation ratios have been analyzed for the mid-Piacen-zian (3.3 to 2.9 Ma) section of Ocean Drilling Program (ODP) Site 1115B, located in the western equatorial Pacific off the coast of New Guinea. Cold and warm season sea surface temperature (SST) estimates were determined using a modern analog technique. ODP Site 1115 is located just south of the transition between the planktic foraminifer tropical and subtropical faunal provinces and approximates the southern boundary of the western equatorial Pacific (WEP) warm pool. Comparison of the faunal and alkenone SST estimates (presented here) with an existing nannofossil climate proxy shows similar trends. Results of this analysis show increased seasonal variability during the middle of the sampled section (3.22 to 3.10 Ma), suggesting a possible northward migration of both the subtropical faunal province and the southern boundary of the WEP warm pool.

Long-term Isothermal Aging Effects on Weight Loss, Compression Properties, and Dimensions of T650-35 Fabric-reinforced PMR-15 Composites-data

NASA Technical Reports Server (NTRS)

Bowles, Kenneth J.; Tsuji, Luis; Kamvouris, John; Roberts, Gary D.

2003-01-01

A cooperative program was conducted with the General Electric Aircraft Engines plant in Evendale, Ohio, to study the effects of long-term isothermal aging at elevated temperatures on compression and thermal durability properties of T650 35 fabric-reinforced PMR 15 composites. This degradation study was conducted over an approximate time period of 3 1/2 yr. The aging temperatures were 204, 260, 288, 316, and 343 C. Specimens of different dimensions were evaluated. Specimens with ratios of the cut edge to total surface area of 0.03 to 0.89 were fabricated and aged. The aged and unaged specimens were tested in compression as specified in Test Method for Compressive Properties of Rigid Plastics (ASTM D695M). Thickness changes, degraded surface layer growth, weight loss, and failure modes were monitored and recorded. All property changes were thickness dependent.

An ab initio variationally computed room-temperature line list for (32)S(16)O3.

PubMed

Underwood, Daniel S; Tennyson, Jonathan; Yurchenko, Sergei N

2013-07-07

Ab initio potential energy and dipole moment surfaces are computed for sulfur trioxide (SO3) at the CCSD(T)-F12b level of theory with appropriate triple-zeta basis sets. The analytical representations of these surfaces are used, with a slight correction, to compute pure rotational and rotation-vibration spectra of (32)S(16)O3 using the variational nuclear motion program TROVE. The calculations considered transitions in the region 0-4000 cm(-1) with rotational states up to J = 85. The resulting line list of 174,674,257 transitions is appropriate for modelling room temperature (32)S(16)O3 spectra. Good agreement is found with the observed infrared absorption spectra and the calculations are used to place the measured relative intensities on an absolute scale. A list of 10,878 experimental transitions is provided in a form suitable for inclusion in standard atmospheric and planetary spectroscopic databases.

Thermal elastohydrodynamic lubrication of spur gears

NASA Technical Reports Server (NTRS)

Wang, K. L.; Cheng, H. S.

1980-01-01

An analysis and computer program called TELSGE were developed to predict the variations of dynamic load, surface temperature, and lubricant film thickness along the contacting path during the engagement of a pair of involute spur gears. The analysis of dynamic load includes the effect of gear inertia, the effect of load sharing of adjacent teeth, and the effect of variable tooth stiffness which are obtained by a finite-element method. Results obtained from TELSGE for the dynamic load distributions along the contacting path for various speeds of a pair of test gears show patterns similar to that observed experimentally. Effects of damping ratio, contact ratio, tip relief, and tooth error on the dynamic load were examined. In addition, two dimensionless charts are included for predicting the maximum equilibrium surface temperature, which can be used to estimate directly the lubricant film thickness based on well established EHD analysis.

The Infrared Sensor Suite for SnowEx 2017

NASA Technical Reports Server (NTRS)

Hall, D. K.; Chickadel, C. C.; Crawford, C. J.; DeMarco, E. L.; Jennings, D. E.; Jhabvala, M. D.; Kim, E. J.; Lundquist, J. D.; Lunsford, A. W.

2017-01-01

SnowEx is a winter airborne and field campaign designed to measure snow-water equivalent in forested landscapes. A major focus of Year 1 (2016-17) of NASA's SnowEx campaign will be an extensive field program involving dozens of participants from U.S. government agencies and from many universities and institutions, both domestic and foreign. Along with other instruments, two infrared (IR) sensors will be flown on a Naval Research Laboratory P-3 aircraft. Surface temperature is a critical input to hydrologic models and will be measured during the SnowEx mission. A Quantum Well Infrared Photodetector (QWIP) IR imaging camera system will be flown along with a KT-15 remote thermometer to aid in the calibration of the IR image data. Together, these instruments will measure surface temperature of snow and ice targets to an expected accuracy of less than 1C.

BOREAS Level-2 MAS Surface Reflectance and Temperature Images in BSQ Format

NASA Technical Reports Server (NTRS)

Hall, Forrest G. (Editor); Newcomer, Jeffrey (Editor); Lobitz, Brad; Spanner, Michael; Strub, Richard; Lobitz, Brad

2000-01-01

The BOReal Ecosystem-Atmosphere Study (BOREAS) Staff Science Aircraft Data Acquisition Program focused on providing the research teams with the remotely sensed aircraft data products they needed to compare and spatially extend point results. The MODIS Airborne Simulator (MAS) images, along with other remotely sensed data, were collected to provide spatially extensive information over the primary study areas. This information includes biophysical parameter maps such as surface reflectance and temperature. Collection of the MAS images occurred over the study areas during the 1994 field campaigns. The level-2 MAS data cover the dates of 21-Jul-1994, 24-Jul-1994, 04-Aug-1994, and 08-Aug-1994. The data are not geographically/geometrically corrected; however, files of relative X and Y coordinates for each image pixel were derived by using the C130 navigation data in a MAS scan model. The data are provided in binary image format files.

LOX/Methane Main Engine Igniter Tests and Modeling

NASA Technical Reports Server (NTRS)

Breisacher, Kevin J.; Ajmani, Kumund

2008-01-01

The LOX/methane propellant combination is being considered for the Lunar Surface Access Module ascent main engine propulsion system. The proposed switch from the hypergolic propellants used in the Apollo lunar ascent engine to LOX/methane propellants requires the development of igniters capable of highly reliable performance in a lunar surface environment. An ignition test program was conducted that used an in-house designed LOX/methane spark torch igniter. The testing occurred in Cell 21 of the Research Combustion Laboratory to utilize its altitude capability to simulate a space vacuum environment. Approximately 750 ignition test were performed to evaluate the effects of methane purity, igniter body temperature, spark energy level and frequency, mixture ratio, flowrate, and igniter geometry on the ability to obtain successful ignitions. Ignitions were obtained down to an igniter body temperature of approximately 260 R with a 10 torr back-pressure. The data obtained is also being used to anchor a CFD based igniter model.

Stabilization of Co{sup 2+} in layered double hydroxides (LDHs) by microwave-assisted ageing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herrero, M.; Benito, P.; Labajos, F.M.

2007-03-15

Co-containing layered double hydroxides at different pH have been prepared, and aged following different routes. The solids prepared have been characterized by element chemical analysis, powder X-ray diffraction, thermogravimetric and differential thermal analyses (both in nitrogen and in oxygen), FT-IR and Vis-UV spectroscopies, temperature-programmed reduction and surface area assessment by nitrogen adsorption at -196 deg. C. The best conditions found to preserve the cobalt species in the divalent oxidation state are preparing the samples at controlled pH, and then submit them to ageing under microwave irradiation. - Graphical abstract: The use of microwave-hydrothermal treatment, controlling both temperature and ageing time,more » permits to synthesize well-crystallized nanomaterials with controlled surface properties. An enhancement in the crystallinity degree and an increase in the particle size are observed when the irradiation time is prolonged.« less

Improving estimates of forest disturbance by combining observations from Landsat time series with U.S

Treesearch

Todd A. Schroeder; Sean P. Healey; Gretchen G. Moisen; Tracey S. Frescino; Warren B. Cohen; Chengquan Huang; Robert E. Kennedy; Zhiqiang Yang

2014-01-01

With earth's surface temperature and human population both on the rise a new emphasis has been placed on monitoring changes to forested ecosystems the world over. In the United States the U.S. Forest Service Forest Inventory and Analysis (FIA) program monitors the forested land base with field data collected over a permanent network of sample plots. Although these...

Air-Sea Enthalpy and Momentum Exchange at Major Hurricane Wind Speeds

DTIC Science & Technology

2010-06-01

momentum fluxes. Hurricane simulations using the Navy Coupled Ocean / Atmosphere Mesoscale Prediction System are also sensitive to the surface flux and sea... Atmospheric Research NWP Numerical Weather Prediction NOAA National Oceanic and Atmospheric Administration PTH Pressure, Temperature, relative Humidity RE87... Oceanic and Atmospheric Administration for organizing the CBLAST field program and collecting the data used for this study. xx THIS PAGE

Infrared Spectra and Binding Energies of Chemical Warfare Nerve Agent Simulants on the Surface of Amorphous Silica

DTIC Science & Technology

2013-06-24

Limited TPD of Water from Zeolite Linde 4A. Thermochim. Acta 1998, 319 (1), 177−184. (43) Palermo, A.; Löffler, D. G. Kinetics of Water Desorption...from Pelletized 4A and 5A Zeolites . Thermochim. Acta 1990, 159, 171−176. (44) Gorte, R. J. Design Parameters for Temperature Programmed Desorption from

Influence of oxygen partial pressure on surface tension and its temperature coefficient of molten iron

NASA Astrophysics Data System (ADS)

Ozawa, S.; Suzuki, S.; Hibiya, T.; Fukuyama, H.

2011-01-01

Influences of oxygen partial pressure, PO2, of ambient atmosphere and temperature on surface tension and its temperature coefficient for molten iron were experimentally investigated by an oscillating droplet method using an electromagnetic levitation furnace. We successfully measured the surface tension of molten iron over a very wide temperature range of 780 K including undercooling condition in a well controlled PO2 atmosphere. When PO2 is fixed at 10-2 Pa at the inlet of the chamber, a "boomerang shape" temperature dependence of surface tension was experimentally observed; surface tension increased and then decreased with increasing temperature. The pure surface tension of molten iron was deduced from the negative temperature coefficient in the boomerang shape temperature dependence. When the surface tension was measured under the H2-containing gas atmosphere, surface tension did not show a linear relationship against temperature. The temperature dependence of the surface tension shows anomalous kink at around 1850 K due to competition between the temperature dependence of PO2 and that of the equilibrium constant of oxygen adsorption.

Comparison of the Defense Meteorological Satellite Program (DMSP) and the NOAA Polar-Orbiting Operational Environmental Satellite (POES) Program,

DTIC Science & Technology

1985-10-01

grid points on 1 /20 lat /long meshI 4 c. SST global scale analysis ( 1 or 100 km lat /long grid) .. d. SST climatic scale analysis (50 or 500 km lat ...long grid) e. SST monthly means (2 1 /20 or 250 km lat /long grid) 3. Analog Sea Surface Temperature Product Set ’-%". V" " a. GOSSTCOMP charts - weekly...Mercator contour charts, each a ., 500 by 500 lat /long segment, 1 °C contour interval b. Regional charts - set of three charts covering the U.S

Deactivation of Pd particles supported on Nb 2O 5/Cu 3Au(1 0 0): SFG and TPD studies from UHV to 100 mbar

NASA Astrophysics Data System (ADS)

Höbel, Frank; Bandara, Athula; Rupprechter, Günther; Freund, Hans-Joachim

2006-02-01

Structural changes that occur on Pd-Nb 2O 5/Cu 3Au(1 0 0) model catalysts upon thermal annealing were followed by sum frequency generation (SFG) and temperature-programmed desorption (TPD) using CO as probe molecule. SFG experiments were performed both under ultrahigh vacuum and mbar pressure. Heating the catalyst to temperatures above 300 K lead to an irreversible 50% decrease in the CO adsorption capacity and modified the remaining adsorption sites. Alterations of the phase between resonant and non-resonant SFG signals upon annealing indicate a change in the electronic structure of the surface, which excludes Pd sintering or migration of Nb 2O 5 over Pd particles to cause the observed effect and rather suggests the formation of "mixed Pd-NbO x" sites. The same changes in surface properties also occur during CO hydrogenation at 1 bar and high temperature, pointing to an involvement of "mixed Pd-NbO x" sites in catalytic reactions.

Validation and Sensitivity Analysis of a New Atmosphere-Soil-Vegetation Model.

NASA Astrophysics Data System (ADS)

Nagai, Haruyasu

2002-02-01

This paper describes details, validation, and sensitivity analysis of a new atmosphere-soil-vegetation model. The model consists of one-dimensional multilayer submodels for atmosphere, soil, and vegetation and radiation schemes for the transmission of solar and longwave radiations in canopy. The atmosphere submodel solves prognostic equations for horizontal wind components, potential temperature, specific humidity, fog water, and turbulence statistics by using a second-order closure model. The soil submodel calculates the transport of heat, liquid water, and water vapor. The vegetation submodel evaluates the heat and water budget on leaf surface and the downward liquid water flux. The model performance was tested by using measured data of the Cooperative Atmosphere-Surface Exchange Study (CASES). Calculated ground surface fluxes were mainly compared with observations at a winter wheat field, concerning the diurnal variation and change in 32 days of the first CASES field program in 1997, CASES-97. The measured surface fluxes did not satisfy the energy balance, so sensible and latent heat fluxes obtained by the eddy correlation method were corrected. By using options of the solar radiation scheme, which addresses the effect of the direct solar radiation component, calculated albedo agreed well with the observations. Some sensitivity analyses were also done for model settings. Model calculations of surface fluxes and surface temperature were in good agreement with measurements as a whole.

The molecular dynamics of adsorption and dissociation of O{sub 2} on Pt(553)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobse, Leon, E-mail: l.jacobse@chem.leidenuniv.nl; Dunnen, Angela den; Juurlink, Ludo B. F.

2015-07-07

Molecular adsorption and dissociation of O{sub 2} on the stepped Pt(553) surface have been investigated using supersonic molecular beam techniques and temperature programmed desorption. The initial and coverage-dependent sticking probability was determined with the King and Wells technique for various combinations of incident kinetic energy, surface temperature, incident angle, and surface coverage. A comparison with similar data for Pt(533) and Pt(110)(1 × 2) shows quantitatively the same high step-induced sticking at low incident energies compared to Pt(111). The enhancement is therefore insensitive to the exact arrangement of atoms forming surface corrugation. We consider energy transfer and electronic effects to explainmore » the enhanced sticking. On the other hand, dissociation dynamics at higher incident kinetic energies are strongly dependent on step type. The Pt(553) and Pt(533) surfaces are more reactive than Pt(111), but the (100) step shows higher sticking than the (110) step. We relate this difference to a variation in the effective lowering of the barrier to dissociation from molecularly adsorbed states into atomic states. Our findings are in line with results from experimental desorption studies and theoretical studies of atomic binding energies. We discuss the influence of the different step types on sticking and dissociation dynamics with a one-dimensional potential energy surface.« less

Recent Climate Changes in Northwestern Qaidam Basin Inferred from Geothermal Gradients

NASA Astrophysics Data System (ADS)

Liu, J.; Zhang, T.

2014-12-01

Temperature perturbations under the ground surface are direct thermal response to ground surface temperature changes. Thus ground surface temperature history can be reconstructed from borehole temperature measurements using borehole paleothermometry inversion method. In this study, we use seven borehole temperature profiles to reconstruct the ground surface temperature variation of the past 500 years of the Qaidam basin, northwestern China. Borehole transient temperature measurement from seven sites in northwestern Qaidam basin were separated from geothermal gradients and analyzed by functional space inversion method to determine past ground surface temperature variations in this region. All temperature profiles show the effects of recent climatic disturbances. Inversion shows an overall increase in ground surface temperature by an averaged 1.2℃ (-0.11~2.21℃) during the last 500 years. Clear signs of a cold period between 1500 and 1900 A.D., corresponding to the Little Ice Age, have been found. Its coldest period was between 1780~1790 A.D. with the ground surface temperature of 5.4℃. During the 19th and the 20th century, reconstructed ground surface temperature shows a rising trend, and in the late 20th century, the temperature started to decrease. However, the highest temperature in 1990s broke the record of the past 500 years. This reconstructed past ground surface temperature variation is verified by the simulated annual surface air temperature computed by EdGCM and the cooling trend is also confirmed by other reconstruction of winter half year minimum temperatures using tree rings on the northeastern Tibetan Plateau.

Silicon Carbide Epitaxial Films Studied by Atomic Force Microscopy

NASA Technical Reports Server (NTRS)

1996-01-01

Silicon carbide (SiC) holds great potential as an electronic material because of its wide band gap energy, high breakdown electric field, thermal stability, and resistance to radiation damage. Possible aerospace applications of high-temperature, high-power, or high-radiation SiC electronic devices include sensors, control electronics, and power electronics that can operate at temperatures up to 600 C and beyond. Commercially available SiC devices now include blue light-emitting diodes (LED's) and high-voltage diodes for operation up to 350 C, with other devices under development. At present, morphological defects in epitaxially grown SiC films limit their use in device applications. Research geared toward reducing the number of structural inhomogeneities can benefit from an understanding of the type and nature of problems that cause defects. The Atomic Force Microscope (AFM) has proven to be a useful tool in characterizing defects present on the surface of SiC epitaxial films. The in-house High-Temperature Integrated Electronics and Sensors (HTIES) Program at the NASA Lewis Research Center not only extended the dopant concentration range achievable in epitaxial SiC films, but it reduced the concentration of some types of defects. Advanced structural characterization using the AFM was warranted to identify the type and structure of the remaining film defects and morphological inhomogeneities. The AFM can give quantitative information on surface topography down to molecular scales. Acquired, in part, in support of the Advanced High Temperature Engine Materials Technology Program (HITEMP), the AFM had been used previously to detect partial fiber debonding in composite material cross sections. Atomic force microscopy examination of epitaxial SiC film surfaces revealed molecular-scale details of some unwanted surface features. Growth pits propagating from defects in the substrate, and hillocks due, presumably, to existing screw dislocations in the substrates, were imaged. Away from local defects, step bunching was observed to yield step heights of hundreds of angstroms, with possible implications for the uniformity of dopants incorporated in SiC devices during fabrication. The quantitative topographic data from the AFM allow the relevant defect information to be extracted, such as the size and distribution of step bunching and the Burgers vector of screw dislocations. These atomic force microscopy results have furthered the understanding of the dynamic epitaxial SiC growth process. A model describing the observed hillock step bunching has been proposed. This cooperation between researchers involved in crystal growth, electronic device fabrication, and surface structural characterization is likely to continue as atomic force microscopy is used to improve SiC films for high-temperature electronic devices for NASA's advanced turbine engines and space power devices, as well as for future applications in the automotive industry.

Low temperature surface passivation of crystalline silicon and its application to interdigitated back contact silicon heterojunction (ibc-shj) solar cell

NASA Astrophysics Data System (ADS)

Shu, Zhan

With the absence of shading loss together with improved quality of surface passivation introduced by low temperature processed amorphous silicon crystalline silicon (a-Si:H/c-Si) heterojunction, the interdigitated back contact silicon heterojunction (IBC-SHJ) solar cell exhibits a potential for higher conversion efficiency and lower cost than a traditional front contact diffused junction solar cell. In such solar cells, the front surface passivation is of great importance to achieve both high open-circuit voltage (Voc) and short-circuit current (Jsc). Therefore, the motivation of this work is to develop a low temperature processed structure for the front surface passivation of IBC-SHJ solar cells, which must have an excellent and stable passivation quality as well as a good anti-reflection property. Four different thin film materials/structures were studied and evaluated for this purpose, namely: amorphous silicon nitride (a-SiNx:H), thick amorphous silicon film (a-Si:H), amorphous silicon/silicon nitride/silicon carbide (a-Si:H/a-SiN x:H/a-SiC:H) stack structure with an ultra-thin a-Si:H layer, and zinc sulfide (ZnS). It was demonstrated that the a-Si:H/a-SiNx:H/a-SiC:H stack surpasses other candidates due to both of its excellent surface passivation quality (SRV<5 cm/s) and lower absorption losses. The low recombination rate at the stack structure passivated c-Si surface is found to be resulted from (i) field effect passivation due to the positive fixed charge (Q fix~1x1011 cm-2 with 5 nm a-Si:H layer) in a-SiNx:H as measured from capacitance-voltage technique, and (ii) reduced defect state density (mid-gap Dit~4x1010 cm-2eV-1) at a-Si:H/c-Si interface provided by a 5 nm thick a-Si:H layer, as characterized by conductance-frequency measurements. Paralleled with the experimental studies, a computer program was developed in this work based on the extended Shockley-Read-Hall (SRH) model of surface recombination. With the help of this program, the experimental injection level dependent SRV curves of the stack passivated c-Si samples were successfully reproduced and the carrier capture cross sections of interface defect states were extracted. Additionally, anti-reflection properties of the stack structure were optimized and optical losses were analyzed. The Voc over 700 mV and Jsc over 38 mA/cm2 were achieved in IBC-SHJ solar cells using the stack structure for front surface passivation. Direct comparison shows that such low temperature deposited stack structure developed in this work achieves comparable device performance to the high temperature processed front surface passivation structure used in other high efficiency IBC solar cells. However, the lower fill factor (FF) of IBC-SHJ solar cell as compared with traditional front a-Si:H/c-Si heterojunction cell (HIT cell) greatly limits the overall performance of these devices. Two-dimensional (2D) simulations were used to comparatively model the HIT and IBC-SHJ solar cells to understand the underlying device physics which controls cell performance. The effects of a wide range of device parameters were investigated in the simulation, and pathways to improve the FF of IBC-SHJ solar cell were suggested.

Seasonal Prediction of Regional Surface Air Temperature and First-flowering Date in South Korea using Dynamical Downscaling

NASA Astrophysics Data System (ADS)

Ahn, J. B.; Hur, J.

2015-12-01

The seasonal prediction of both the surface air temperature and the first-flowering date (FFD) over South Korea are produced using dynamical downscaling (Hur and Ahn, 2015). Dynamical downscaling is performed using Weather Research and Forecast (WRF) v3.0 with the lateral forcing from hourly outputs of Pusan National University (PNU) coupled general circulation model (CGCM) v1.1. Gridded surface air temperature data with high spatial (3km) and temporal (daily) resolution are obtained using the physically-based dynamical models. To reduce systematic bias, simple statistical correction method is then applied to the model output. The FFDs of cherry, peach and pear in South Korea are predicted for the decade of 1999-2008 by applying the corrected daily temperature predictions to the phenological thermal-time model. The WRF v3.0 results reflect the detailed topographical effect, despite having cold and warm biases for warm and cold seasons, respectively. After applying the correction, the mean temperature for early spring (February to April) well represents the general pattern of observation, while preserving the advantages of dynamical downscaling. The FFD predictabilities for the three species of trees are evaluated in terms of qualitative, quantitative and categorical estimations. Although FFDs derived from the corrected WRF results well predict the spatial distribution and the variation of observation, the prediction performance has no statistical significance or appropriate predictability. The approach used in the study may be helpful in obtaining detailed and useful information about FFD and regional temperature by accounting for physically-based atmospheric dynamics, although the seasonal predictability of flowering phenology is not high enough. Acknowledgements This work was carried out with the support of the Rural Development Administration Cooperative Research Program for Agriculture Science and Technology Development under Grant Project No. PJ009953 and Project No. PJ009353, Republic of Korea. Reference Hur, J., J.-B. Ahn, 2015. Seasonal Prediction of Regional Surface Air Temperature and First-flowering Date over South Korea, Int. J. Climatol., DOI: 10.1002/joc.4323.

Inventory of File nam.t00z.smartconus06.tm00.grib2

Science.gov Websites

Temperature [K] 002 surface DPT 6 hour fcst Dew Point Temperature [K] 003 surface SPFH 6 hour fcst Specific Index [K] 027 surface HINDEX 6 hour fcst Haines Index [Numeric] 028 surface TMP 5 hour fcst Temperature [K] 029 surface TMP 4 hour fcst Temperature [K] 030 surface DPT 5 hour fcst Dew Point Temperature [K

Inventory of File gfs.t06z.smartguam12.tm00.grib2

Science.gov Websites

Temperature [K] 002 surface DPT 12 hour fcst Dew Point Temperature [K] 003 surface SPFH 12 hour fcst Specific Best (4 layer) Lifted Index [K] 020 surface TMP 11 hour fcst Temperature [K] 021 surface TMP 10 hour fcst Temperature [K] 022 surface DPT 11 hour fcst Dew Point Temperature [K] 023 surface DPT 10 hour

Inventory of File nam.t00z.smartak06.tm00.grib2

Science.gov Websites

Temperature [K] 002 surface DPT 6 hour fcst Dew Point Temperature [K] 003 surface SPFH 6 hour fcst Specific Haines Index [Numeric] 029 surface TMP 5 hour fcst Temperature [K] 030 surface TMP 4 hour fcst Temperature [K] 031 surface DPT 5 hour fcst Dew Point Temperature [K] 032 surface DPT 4 hour fcst Dew Point

Inventory of File nam.t00z.smartconus12.tm00.grib2

Science.gov Websites

Temperature [K] 002 surface DPT 12 hour fcst Dew Point Temperature [K] 003 surface SPFH 12 hour fcst Specific hour fcst Haines Index [Numeric] 030 surface TMP 11 hour fcst Temperature [K] 031 surface TMP 10 hour fcst Temperature [K] 032 surface DPT 11 hour fcst Dew Point Temperature [K] 033 surface DPT 10 hour

Studies on in-vessel debris coolability in ALPHA program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maruyama, Yu; Yamano, Norihiro; Moriyama, Kiyofumi

1997-02-01

In-vessel debris coolability experiments have been performed in ALPHA Program at JAERI. Aluminum oxide (Al{sub 2}O{sub 3}) produced by a thermite reaction was applied as a debris simulant. Two scoping experiments using approximately 30 kg or 50 kg of Al{sub 2}O{sub 3} were conducted. In addition to post-test observations, temperature histories of the debris simulant and the lower head experimental vessel were evaluated. Rapid temperature reduction observed on the outer surface of the experimental vessel may imply that water penetration into a gap between the solidified debris and the experimental vessel occurred resulting in an effective cooling of once heatedmore » vessel wall. Preliminary measurement of a gap width was made with an ultrasonic device. Signals to show the existence of gaps, ranging from 0.7 mm to 1.4 mm, were detected at several locations.« less

Exploration criteria for low permeability geothermal resources. Final report. [Coso KGRA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norton, D.

1977-10-01

Low permeability geothermal systems related to high temperature plutons in the upper crust were analyzed in order to ascertain those characteristics of these systems which could be detected by surface and shallow subsurface exploration methods. Analyses were designed to integrate data and concepts from the literature, which relate to the transport processes, together with computer simulation of idealized systems. The systems were analyzed by systematically varying input parameters in order to understand their effect on the variables which might be measured in an exploration-assessment program. The methods were applied to a prospective system in its early stages of evaluation. Datamore » from the Coso system were used. The study represents a first-order approximation to transport processes in geothermal systems, which consist of high temperature intrusions, host rock, and fluids. Included in an appendix are operations procedures for interactive graphics programs developed during the study. (MHR)« less

Cross-scale modeling of surface temperature and tree seedling establishment inmountain landscapes

USGS Publications Warehouse

Dingman, John; Sweet, Lynn C.; McCullough, Ian M.; Davis, Frank W.; Flint, Alan L.; Franklin, Janet; Flint, Lorraine E.

2013-01-01

Abstract: Introduction: Estimating surface temperature from above-ground field measurements is important for understanding the complex landscape patterns of plant seedling survival and establishment, processes which occur at heights of only several centimeters. Currently, future climate models predict temperature at 2 m above ground, leaving ground-surface microclimate not well characterized. Methods: Using a network of field temperature sensors and climate models, a ground-surface temperature method was used to estimate microclimate variability of minimum and maximum temperature. Temperature lapse rates were derived from field temperature sensors and distributed across the landscape capturing differences in solar radiation and cold air drainages modeled at a 30-m spatial resolution. Results: The surface temperature estimation method used for this analysis successfully estimated minimum surface temperatures on north-facing, south-facing, valley, and ridgeline topographic settings, and when compared to measured temperatures yielded an R2 of 0.88, 0.80, 0.88, and 0.80, respectively. Maximum surface temperatures generally had slightly more spatial variability than minimum surface temperatures, resulting in R2 values of 0.86, 0.77, 0.72, and 0.79 for north-facing, south-facing, valley, and ridgeline topographic settings. Quasi-Poisson regressions predicting recruitment of Quercus kelloggii (black oak) seedlings from temperature variables were significantly improved using these estimates of surface temperature compared to air temperature modeled at 2 m. Conclusion: Predicting minimum and maximum ground-surface temperatures using a downscaled climate model coupled with temperature lapse rates estimated from field measurements provides a method for modeling temperature effects on plant recruitment. Such methods could be applied to improve projections of species’ range shifts under climate change. Areas of complex topography can provide intricate microclimates that may allow species to redistribute locally as climate changes.

Interaction of Formaldehyde with the Rutile TiO 2 (110) Surface: A Combined Experimental and Theoretical Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Xiaojuan; Zhang, Zhenrong; Yang, Chengwu

2016-06-16

The adsorption and reaction of formaldehyde (CH 2O) on the oxidized rutile TiO 2(110) surface were studied by temperature programmed desorption (TPD), scanning tunneling microscopy (STM), infrared reflection-absorption spectroscopy (IRRAS) and density functional theory (DFT) calculations. The experimental and theoretical data reveal the presence of various species depending on the temperature and coverage. After formaldehyde adsorption on TiO 2(110) at 65 K, the multilayer CH 2O was detected, which desorbs completely upon heating to 120 K. The isolated CH 2O monomer was identified after submonolayer adsorption at low temperatures (45-65 K), in which CH 2O is bound to the surfacemore » Ti5c sites via σ-donation and adopts a tilted geometry. With heating to higher temperatures the CH 2O monomers remain stable up to 70 K and then undergo coupling reactions to form paraformaldehyde (polyoxymethylene, POM) at the Ti 5c rows. The POM chain is oriented primarily along the [001] direction in a slightly disordered configuration. POM becomes the predominant species at 120 K and is decomposed releasing CH 2O at about 250 K. In addition, dioxymethylene (DOM) was detected as minority species formed via reaction of Ti 5c-bound CH 2O with both neighboring O 2c along the [1-10] direction and oxygen adatoms (Oad) at Ti 5c sites along [001] on the oxidized TiO 2(110) surface.« less

Retrievals of Sea Surface Emissivity and Skin Temperature from M-AERI Observations from the ACAPEX/CalWater2 Campaign

NASA Astrophysics Data System (ADS)

Gero, P. J.; Westphall, M.; Knuteson, R.; Knuteson, R. O.; Smith, W.

2016-12-01

The Atmospheric Emitted Radiance Interferometer (AERI) is a ground-based instrument developed at the University of Wisconsin-Madison that measures downwelling thermal infrared radiance from the atmosphere. Observations are made in the 520-3020 cm-1 (3.3-19 μm) spectral range with a resolution of 1 cm-1, with an accuracy better than 1% of ambient radiance. These observations can be used to obtain vertical profiles of tropospheric temperature and water vapor in the lowest 3 km of the troposphere, as well as measurements of the concentration of various trace gases and microphysical and optical properties of clouds and aerosols. The U.S Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) program currently operates about ten AERIs at various fixed and mobile sites worldwide, addressing a diverse range of scientific goals from process studies to long-term climate observations. One of the instruments is a marine version (M-AERI) that has the capability to view scenes ±45° from the horizon, and can be used to observe sea surface properties such as skin temperature and emissivity. The M-AERI was deployed on the NOAA Ship Ronald Brown in 2015 as part of the ACAPEX/CalWater2 campaign to study atmospheric rivers in the Pacific Ocean. We present results from the M-AERI from this campaign of retrievals of skin temperature and sea surface emissivity as a function of view angle and wind speed, as well as comparisons to various models.

In situ TEM and synchrotron characterization of U–10Mo thin specimen annealed at the fast reactor temperature regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yun, Di, E-mail: diyun1979@xjtu.edu.cn; Xi'an Jiao Tong University, 28 Xian Ning West Road, Xi'an 710049; Mo, Kun

2015-12-15

U–Mo metallic alloys have been extensively used for the Reduced Enrichment for Research and Test Reactors (RERTR) program, which is now known as the Office of Material Management and Minimization under the Conversion Program. This fuel form has also recently been proposed as fast reactor metallic fuels in the recent DOE Ultra-high Burnup Fast Reactor project. In order to better understand the behavior of U–10Mo fuels within the fast reactor temperature regime, a series of annealing and characterization experiments have been performed. Annealing experiments were performed in situ at the Intermediate Voltage Electron Microscope (IVEM-Tandem) facility at Argonne National Laboratorymore » (ANL). An electro-polished U–10Mo alloy fuel specimen was annealed in situ up to 700 °C. At an elevated temperature of about 540 °C, the U–10Mo specimen underwent a relatively slow microstructure transition. Nano-sized grains were observed to emerge near the surface. At the end temperature of 700 °C, the near-surface microstructure had evolved to a nano-crystalline state. In order to clarify the nature of the observed microstructure, Laue diffraction and powder diffraction experiments were carried out at beam line 34-ID of the Advanced Photon Source (APS) at ANL. Phases present in the as-annealed specimen were identified with both Laue diffraction and powder diffraction techniques. The U–10Mo was found to recrystallize due to thermally-induced recrystallization driven by a high density of pre-existing dislocations. A separate in situ annealing experiment was carried out with a Focused Ion Beam processed (FIB) specimen. A similar microstructure transition occurred at a lower temperature of about 460 °C with a much faster transition rate compared to the electro-polished specimen. - Highlights: • TEM annealing experiments were performed in situ at the IVEM facility up to fast reactor temperature. • At 540 °C, the U-10Mo specimen underwent a slow microstructure transition where nano-sized grains were observed to emerge. • UO{sub 2} phase exists at the thin area of the as-annealed specimen whereas U-10Mo γ phase dominated at the thicker part. • Bcc γ U-10Mo recrystallized to become nano-meter sized crystallites near the specimen surface. • A separateannealing experiment was conducted with a FIB processed specimen where similar transition occurred at a lower temperature of 460 °C with a faster rate.« less

Temperature distribution and heat radiation of patterned surfaces at short wavelengths.

PubMed

Emig, Thorsten

2017-05-01

We analyze the equilibrium spatial distribution of surface temperatures of patterned surfaces. The surface is exposed to a constant external heat flux and has a fixed internal temperature that is coupled to the outside heat fluxes by finite heat conductivity across the surface. It is assumed that the temperatures are sufficiently high so that the thermal wavelength (a few microns at room temperature) is short compared to all geometric length scales of the surface patterns. Hence the radiosity method can be employed. A recursive multiple scattering method is developed that enables rapid convergence to equilibrium temperatures. While the temperature distributions show distinct dependence on the detailed surface shapes (cuboids and cylinder are studied), we demonstrate robust universal relations between the mean and the standard deviation of the temperature distributions and quantities that characterize overall geometric features of the surface shape.

Temperature distribution and heat radiation of patterned surfaces at short wavelengths

NASA Astrophysics Data System (ADS)

Emig, Thorsten

2017-05-01

We analyze the equilibrium spatial distribution of surface temperatures of patterned surfaces. The surface is exposed to a constant external heat flux and has a fixed internal temperature that is coupled to the outside heat fluxes by finite heat conductivity across the surface. It is assumed that the temperatures are sufficiently high so that the thermal wavelength (a few microns at room temperature) is short compared to all geometric length scales of the surface patterns. Hence the radiosity method can be employed. A recursive multiple scattering method is developed that enables rapid convergence to equilibrium temperatures. While the temperature distributions show distinct dependence on the detailed surface shapes (cuboids and cylinder are studied), we demonstrate robust universal relations between the mean and the standard deviation of the temperature distributions and quantities that characterize overall geometric features of the surface shape.

The forcing of southwestern Asia teleconnections by low-frequency sea surface temperature variability during boreal winter

USGS Publications Warehouse

Hoell, Andrew; Funk, Christopher C.; Mathew Barlow,

2015-01-01

Southwestern Asia, defined here as the domain bounded by 20°–40°N and 40°–70°E, which includes the nations of Iraq, Iran, Afghanistan, and Pakistan, is a water-stressed and semiarid region that receives roughly 75% of its annual rainfall during November–April. The November–April climate of southwestern Asia is strongly influenced by tropical Indo-Pacific variability on intraseasonal and interannual time scales, much of which can be attributed to sea surface temperature (SST) variations. The influences of lower-frequency SST variability on southwestern Asia climate during November–April Pacific decadal SST (PDSST) variability and the long-term trend in SST (LTSST) is examined. The U.S. Climate Variability and Predictability Program (CLIVAR) Drought Working Group forced global atmospheric climate models with PDSST and LTSST patterns, identified using empirical orthogonal functions, to show the steady atmospheric response to these modes of decadal to multidecadal SST variability. During November–April, LTSST forces an anticyclone over southwestern Asia, which results in reduced precipitation and increases in surface temperature. The precipitation and tropospheric circulation influences of LTSST are corroborated by independent observed precipitation and circulation datasets during 1901–2004. The decadal variations of southwestern Asia precipitation may be forced by PDSST variability, with two of the three models indicating that the cold phase of PDSST forces an anticyclone and precipitation reductions. However, there are intermodel circulation variations to PDSST that influence subregional precipitation patterns over the Middle East, southwestern Asia, and subtropical Asia. Changes in wintertime temperature and precipitation over southwestern Asia forced by LTSST and PDSST imply important changes to the land surface hydrology during the spring and summer.

Investigation of Cyprus thermal tenancy using nine year MODIS LST data and Fourier analysis

NASA Astrophysics Data System (ADS)

Skarlatos, D.; Miliaresis, G.; Georgiou, A.

2013-08-01

Land Surface Temperature (LST) is an extremely important parameter that controls the exchange of long wave radiation between surface and atmosphere. It is a good indicator of the energy balance at the Earth's surface and it is one of the key parameters in the physics of land-surface processes on regional as well as global scale. This paper utilizes monthly night and day averaged LST MODIS imagery over Cyprus for a 9 year period. Fourier analysis and Least squares estimation fitting are implemented to analyze mean daily data over Cyprus in an attempt to investigate possible temperature tenancy over these years and possible differences among areas with different land cover and land use, such as Troodos Mountain and Nicosia, the main city in the center of the island. The analysis of data over a long time period, allows questions such as whether there is a tenancy to temperature increase, to be answered in a statistically better way, provided that `noise' is removed correctly. Dealing with a lot of data, always provides a more accurate estimation, but on the other hand, more noise in implemented on the data, especially when dealing with temperature which is subject to daily and annual cycles. A brief description over semi-automated data acquisition and standardization using object-oriented programming and GIS-based techniques, will be presented. The paper fully describes the time series analysis implemented, the Fourier method and how it was used to analyze and filter mean daily data with high frequency. Comparison of mean monthly daily LST against day and night LSTs is also performed over the 9 year period in order to investigate whether use of the extended data series provide significant advantage over short.

RECOVERY ACT: MULTIMODAL IMAGING FOR SOLAR CELL MICROCRACK DETECTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janice Hudgings; Lawrence Domash

2012-02-08

Undetected microcracks in solar cells are a principal cause of failure in service due to subsequent weather exposure, mechanical flexing or diurnal temperature cycles. Existing methods have not been able to detect cracks early enough in the production cycle to prevent inadvertent shipment to customers. This program, sponsored under the DOE Photovoltaic Supply Chain and Cross-Cutting Technologies program, studied the feasibility of quantifying surface micro-discontinuities by use of a novel technique, thermoreflectance imaging, to detect surface temperature gradients with very high spatial resolution, in combination with a suite of conventional imaging methods such as electroluminescence. The project carried out laboratorymore » tests together with computational image analyses using sample solar cells with known defects supplied by industry sources or DOE National Labs. Quantitative comparisons between the effectiveness of the new technique and conventional methods were determined in terms of the smallest detectable crack. Also the robustness of the new technique for reliable microcrack detection was determined at various stages of processing such as before and after antireflectance treatments. An overall assessment is that the new technique compares favorably with existing methods such as lock-in thermography or ultrasonics. The project was 100% completed in Sept, 2010. A detailed report of key findings from this program was published as: Q.Zhou, X.Hu, K.Al-Hemyari, K.McCarthy, L.Domash and J.Hudgings, High spatial resolution characterization of silicon solar cells using thermoreflectance imaging, J. Appl. Phys, 110, 053108 (2011).« less

Counter-current thermocapillary migration of bubbles in self-rewetting liquids

NASA Astrophysics Data System (ADS)

Nazareth, R.; Saenz, P.; Sefiane, K.; Kim, J.; Valluri, P.

2016-11-01

In this work, we study the counter-current thermocapillary propulsion of a suspended bubble in the fluid flowing inside a channel subject to an axial temperature gradient when the surface tension dependence on temperature is non-monotonic. We use direct numerical simulations to address the two-phase conservation of mass, momentum and energy with a volume-of-fluid method to resolve the deformable interface. Two distinct regimes of counter-current bubble migration are characterized: i) "exponential decay" where the bubble decelerates rapidly until it comes to a halt at the spatial position corresponding to the minimum surface tension and ii) "sustained oscillations" where the bubble oscillates about the point of minimum surface tension. We illustrate how these sustained oscillations arise at low capillary number O(10-5) and moderate Reynolds number O(10) and, they are dampened by viscosity at lower Reynolds number. These results are in agreement with the experiments by Shanahan and Sefiane (Sci. Rep. 4, 2014). The work was supported by the Science without Borders program from CAPES agency of Brazilian Ministry of Education and the European Commission's Thermapower Project (294905).

Surface Response of Brominated Carbon Media on Laser and Thermal Excitation: Optical and Thermal Analysis Study.

PubMed

Multian, Volodymyr V; Kinzerskyi, Fillip E; Vakaliuk, Anna V; Grishchenko, Liudmyla M; Diyuk, Vitaliy E; Boldyrieva, Olga Yu; Kozhanov, Vadim O; Mischanchuk, Oleksandr V; Lisnyak, Vladyslav V; Gayvoronsky, Volodymyr Ya

2017-12-01

The present study is objected to develop an analytical remote optical diagnostics of the functionalized carbons surface. Carbon composites with up to 1 mmol g -1 of irreversibly adsorbed bromine were produced by the room temperature plasma treatment of an activated carbon fabric (ACF) derived from polyacrylonitrile textile. The brominated ACF (BrACF) was studied by elastic optical scattering indicatrix analysis at wavelength 532 nm. The obtained data were interpreted within results of the thermogravimetric analysis, X-ray photoelectron spectroscopy and temperature programmed desorption mass spectrometry. The bromination dramatically reduces the microporosity producing practically non-porous material, while the incorporated into the micropores bromine induces the dielectric and structural impact on surface polarizability and conductivity due to the charging effect. We have found that the elastic optical scattering in proper solid angles in the forward and the backward hemispheres is sensitive to the kind of the bromine bonding, e.g., physical adsorption or chemisorption, and the bromination level, respectively, that can be utilized for the express remote fabrication control of the nanoscale carbons with given interfaces.

Analysis of Vegetation Index Variations and the Asian Monsoon Climate

NASA Technical Reports Server (NTRS)

Shen, Sunhung; Leptoukh, Gregory G.; Gerasimov, Irina

2012-01-01

Vegetation growth depends on local climate. Significant anthropogenic land cover and land use change activities over Asia have changed vegetation distribution as well. On the other hand, vegetation is one of the important land surface variables that influence the Asian Monsoon variability through controlling atmospheric energy and water vapor conditions. In this presentation, the mean and variations of vegetation index of last decade at regional scale resolution (5km and higher) from MODIS have been analyzed. Results indicate that the vegetation index has been reduced significantly during last decade over fast urbanization areas in east China, such as Yangtze River Delta, where local surface temperatures were increased significantly in term of urban heat Island. The relationship between vegetation Index and climate (surface temperature, precipitation) over a grassland in northern Asia and over a woody savannas in southeast Asia are studied. In supporting Monsoon Asian Integrated Regional Study (MAIRS) program, the data in this study have been integrated into Giovanni, the online visualization and analysis system at NASA GES DISC. Most images in this presentation are generated from Giovanni system.

Concentration transient analysis of antimony surface segregation during Si(100) molecular beam epitaxy

NASA Technical Reports Server (NTRS)

Markert, L. C.; Greene, J. E.; Ni, W.-X.; Hansson, G. V.; Sundgren, J.-E.

1991-01-01

Antimony surface segregation during Si(100) molecular beam epitaxy (MBE) was investigated at temperatures T(sub s) = 515 - 800 C using concentration transient analysis (CTA). The dopant surface coverage Theta, bulk fraction gamma, and incorporation probability sigma during MBE were determined from secondary-ion mass spectrometry depth profiles of modulation-doped films. Programmed T(sub s) changes during growth were used to trap the surface-segregated dopant overlayer, producing concentration spikes whose integrated area corresponds to Theta. Thermal antimony doping by coevaporation was found to result in segregation strongly dependent on T(sub s) with Theta(sub Sb) values up to 0.9 monolayers (ML): in films doped with Sb(+) ions accelerated by 100 V, Theta(sub Sb) was less than or equal to 4 x 10(exp -3) ML. Surface segregation of coevaporated antimony was kinematically limited for the film growth conditions in these experiments.

Design, fabrication and test of a liquid hydrogen titanium honeycomb cryogenic test tank for use as a reusable launch vehicle main propellant tank

NASA Astrophysics Data System (ADS)

Stickler, Patrick B.; Keller, Peter C.

1998-01-01

Reusable Launch Vehicles (RLV's) utilizing LOX\\LH2 as the propellant require lightweight durable structural systems to meet mass fraction goals and to reduce overall systems operating costs. Titanium honeycomb sandwich with flexible blanket TPS on the windward surface is potentially the lightest-weight and most operable option. Light weight is achieved in part because the honeycomb sandwich tank provides insulation to its liquid hydrogen contents, with no need for separate cryogenic insulation, and in part because the high use temperature of titanium honeycomb reduces the required surface area of re-entry thermal protection systems. System operability is increased because TPS needs to be applied only to surfaces where temperatures exceed approximately 650 K. In order to demonstrate the viability of a titanium sandwich constructed propellant tank, a technology demonstration program was conducted including the design, fabrication and testing of a propellant tank-TPS system. The tank was tested in controlled as well as ambient environments representing ground hold conditions for a RLV main propellant tank. Data collected during each test run was used to validate predictions for air liquefaction, outside wall temperature, boil-off rates, frost buildup and its insulation effects, and the effects of placing a thermal protection system blanket on the external surface. Test results indicated that titanium honeycomb, when used as a RLV propellant tank material, has great promise as a light-weight structural system.

Microstructures and growth mechanisms of GaN films epitaxially grown on AlN/Si hetero-structures by pulsed laser deposition at different temperatures

PubMed Central

Wang, Wenliang; Yang, Weijia; Lin, Yunhao; Zhou, Shizhong; Li, Guoqiang

2015-01-01

2 inch-diameter GaN films with homogeneous thickness distribution have been grown on AlN/Si(111) hetero-structures by pulsed laser deposition (PLD) with laser rastering technique. The surface morphology, crystalline quality, and interfacial property of as-grown GaN films are characterized in detail. By optimizing the laser rastering program, the ~300 nm-thick GaN films grown at 750 °C show a root-mean-square (RMS) thickness inhomogeneity of 3.0%, very smooth surface with a RMS surface roughness of 3.0 nm, full-width at half-maximums (FWHMs) for GaN(0002) and GaN(102) X-ray rocking curves of 0.7° and 0.8°, respectively, and sharp and abrupt AlN/GaN hetero-interfaces. With the increase in the growth temperature from 550 to 850 °C, the surface morphology, crystalline quality, and interfacial property of as-grown ~300 nm-thick GaN films are gradually improved at first and then decreased. Based on the characterizations, the corresponding growth mechanisms of GaN films grown on AlN/Si hetero-structures by PLD with various growth temperatures are hence proposed. This work would be beneficial to understanding the further insight of the GaN films grown on Si(111) substrates by PLD for the application of GaN-based devices. PMID:26563573

Near-surface temperature inversion during summer at Summit, Greenland, and its relation to MODIS-derived surface temperatures

NASA Astrophysics Data System (ADS)

Adolph, Alden C.; Albert, Mary R.; Hall, Dorothy K.

2018-03-01

As rapid warming of the Arctic occurs, it is imperative that climate indicators such as temperature be monitored over large areas to understand and predict the effects of climate changes. Temperatures are traditionally tracked using in situ 2 m air temperatures and can also be assessed using remote sensing techniques. Remote sensing is especially valuable over the Greenland Ice Sheet, where few ground-based air temperature measurements exist. Because of the presence of surface-based temperature inversions in ice-covered areas, differences between 2 m air temperature and the temperature of the actual snow surface (referred to as skin temperature) can be significant and are particularly relevant when considering validation and application of remote sensing temperature data. We present results from a field campaign extending from 8 June to 18 July 2015, near Summit Station in Greenland, to study surface temperature using the following measurements: skin temperature measured by an infrared (IR) sensor, 2 m air temperature measured by a National Oceanic and Atmospheric Administration (NOAA) meteorological station, and a Moderate Resolution Imaging Spectroradiometer (MODIS) surface temperature product. Our data indicate that 2 m air temperature is often significantly higher than snow skin temperature measured in situ, and this finding may account for apparent biases in previous studies of MODIS products that used 2 m air temperature for validation. This inversion is present during our study period when incoming solar radiation and wind speed are both low. As compared to our in situ IR skin temperature measurements, after additional cloud masking, the MOD/MYD11 Collection 6 surface temperature standard product has an RMSE of 1.0 °C and a mean bias of -0.4 °C, spanning a range of temperatures from -35 to -5 °C (RMSE = 1.6 °C and mean bias = -0.7 °C prior to cloud masking). For our study area and time series, MODIS surface temperature products agree with skin surface temperatures better than previous studies indicated, especially at temperatures below -20 °C, where other studies found a significant cold bias. We show that the apparent cold bias present in other comparisons of 2 m air temperature and MODIS surface temperature may be a result of the near-surface temperature inversion. Further investigation of how in situ IR skin temperatures compare to MODIS surface temperature at lower temperatures (below -35 °C) is warranted to determine whether a cold bias exists for those temperatures.

Inventory of File nam.t00z.smartak03.tm00.grib2

Science.gov Websites

Temperature [K] 002 surface DPT 3 hour fcst Dew Point Temperature [K] 003 surface SPFH 3 hour fcst Specific fcst Haines Index [Numeric] 026 surface TMP 2 hour fcst Temperature [K] 027 surface TMP 1 hour fcst Temperature [K] 028 surface DPT 2 hour fcst Dew Point Temperature [K] 029 surface DPT 1 hour fcst Dew Point

Adsorption and reaction of CO and H2O on WC(0001) surface: A first-principles investigation

NASA Astrophysics Data System (ADS)

Tong, Yu-Jhe; Wu, Shiuan-Yau; Chen, Hsin-Tsung

2018-01-01

We have performed a spin-polarized density functional theory (DFT) study for understanding the detailed reaction mechanism of CO and H2O on WC (0001) surface. The adsorption properties and vibrational frequencies of H2O, OH, O, H, CO and CO2 on the WC (0001) surface were illustrated. These results are well in consistent with the experimental observations studied by temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). Based on the adsorption results, potential energy profiles of H2O and OH dehydrogenation and HCO, COH, COOH, and CO2 formation on the WC (0001) surface were predicted. The calculation results demonstrated that the WC (0001) surface as Fe (110) surface exhibits significantly reaction activity toward the dehydrogenation of H2O and OH but less activity toward the formation of HCO, COH, COOH and CO2 compared to the Cu (111) and Pt (111) surfaces.

Lessons learned from the development and manufacture of ceramic reusable surface insulation materials for the space shuttle orbiters

NASA Technical Reports Server (NTRS)

Banas, R. P.; Elgin, D. R.; Cordia, E. R.; Nickel, K. N.; Gzowski, E. R.; Aguiler, L.

1983-01-01

Three ceramic, reusable surface insulation materials and two borosilicate glass coatings were used in the fabrication of tiles for the Space Shuttle orbiters. Approximately 77,000 tiles were made from these materials for the first three orbiters, Columbia, Challenger, and Discovery. Lessons learned in the development, scale up to production and manufacturing phases of these materials will benefit future production of ceramic reusable surface insulation materials. Processing of raw materials into tile blanks and coating slurries; programming and machining of tiles using numerical controlled milling machines; preparing and spraying tiles with the two coatings; and controlling material shrinkage during the high temperature (2100-2275 F) coating glazing cycles are among the topics discussed.

Adsorption and Dissociation of CO2 on Ru(0001)

PubMed Central

2017-01-01

The adsorption and dissociation of carbon dioxide on a Ru(0001) single crystal surface was investigated by reflection–absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) spectroscopy for CO2 adsorbed at 85 K. RAIRS spectroscopy shows that the adsorption of CO2 on a Ru(0001) single crystal is partially dissociative, resulting in CO2 and CO. The CO vibrational mode was also observed to split into two distinct modes, indicating two general populations of CO present at the surface. Furthermore, a time-dependent blue-shift is observed, which is characteristic of increasing CO surface coverage. TPD showed that coverages of up to 0.3 ML were obtained, and no evidence for chemisorption of oxygen on ruthenium was found. PMID:28413569

Surface Emissivity Effects on Thermodynamic Retrieval of IR Spectral Radiance

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Larar, Allen M.; Smith, William L.; Liu, Xu

2006-01-01

The surface emissivity effect on the thermodynamic parameters (e.g., the surface skin temperature, atmospheric temperature, and moisture) retrieved from satellite infrared (IR) spectral radiance is studied. Simulation analysis demonstrates that surface emissivity plays an important role in retrieval of surface skin temperature and terrestrial boundary layer (TBL) moisture. NAST-I ultraspectral data collected during the CLAMS field campaign are used to retrieve thermodynamic properties of the atmosphere and surface. The retrievals are then validated by coincident in-situ measurements, such as sea surface temperature, radiosonde temperature and moisture profiles. Retrieved surface emissivity is also validated by that computed from the observed radiance and calculated emissions based on the retrievals of surface temperature and atmospheric profiles. In addition, retrieved surface skin temperature and emissivity are validated together by radiance comparison between the observation and retrieval-based calculation in the window region where atmospheric contribution is minimized. Both simulation and validation results have lead to the conclusion that variable surface emissivity in the inversion process is needed to obtain accurate retrievals from satellite IR spectral radiance measurements. Retrieval examples are presented to reveal that surface emissivity plays a significant role in retrieving accurate surface skin temperature and TBL thermodynamic parameters.

Estimating the urban bias of surface shelter temperatures using upper-air and satellite data. Part 2: Estimation of the urban bias

NASA Technical Reports Server (NTRS)

Epperson, David L.; Davis, Jerry M.; Bloomfield, Peter; Karl, Thomas R.; Mcnab, Alan L.; Gallo, Kevin P.

1995-01-01

A methodology is presented for estimating the urban bias of surface shelter temperatures due to the effect of the urban heat island. Multiple regression techniques were used to predict surface shelter temperatures based on the time period 1986-89 using upper-air data from the European Centre for Medium-Range Weather Forecasts (ECMWF) to represent the background climate, site-specific data to represent the local landscape, and satellite-derived data -- the normalized difference vegetation index (NDVI) and the Defense Meteorological Satellite Program (DMSP) nighttime brightness data -- to represent the urban and rural landscape. Local NDVI and DMSP values were calculated for each station using the mean NDVI and DMSP values from a 3 km x 3 km area centered over the given station. Regional NDVI and DMSP values were calculated to represent a typical rural value for each station using the mean NDVI and DMSP values from a 1 deg x 1 deg latitude-longitude area in which the given station was located. Models for the United States were then developed for monthly maximum, mean, and minimum temperatures using data from over 1000 stations in the U.S. Cooperative (COOP) Network and for monthly mean temperatures with data from over 1150 stations in the Global Historical Climate Network (GHCN). Local biases, or the differences between the model predictions using the observed NDVI and DMSP values, and the predictions using the background regional values were calculated and compared with the results of other research. The local or urban bias of U.S. temperatures, as derived from all U.S. stations (urban and rural) used in the models, averaged near 0.40 C for monthly minimum temperatures, near 0.25 C for monthly mean temperatures, and near 0.10 C for monthly maximum temperatures. The biases of monthly minimum temperatures for individual stations ranged from near -1.1 C for rural stations to 2.4 C for stations from the largest urban areas. The results of this study indicate minimal problems for global application once global NDVI and DMSP data become available.

Design of a Low Power, Fast-Spectrum, Liquid-Metal Cooled Surface Reactor System

NASA Astrophysics Data System (ADS)

Marcille, T. F.; Dixon, D. D.; Fischer, G. A.; Doherty, S. P.; Poston, D. I.; Kapernick, R. J.

2006-01-01

In the current 2005 US budget environment, competition for fiscal resources make funding for comprehensive space reactor development programs difficult to justify and accommodate. Simultaneously, the need to develop these systems to provide planetary and deep space-enabling power systems is increasing. Given that environment, designs intended to satisfy reasonable near-term surface missions, using affordable technology-ready materials and processes warrant serious consideration. An initial lunar application design incorporating a stainless structure, 880 K pumped NaK coolant system and a stainless/UO2 fuel system can be designed, fabricated and tested for a fraction of the cost of recent high-profile reactor programs (JIMO, SP-100). Along with the cost reductions associated with the use of qualified materials and processes, this design offers a low-risk, high-reliability implementation associated with mission specific low temperature, low burnup, five year operating lifetime requirements.

A review of turbulent-boundary-layer heat transfer research at Stanford, 1958-1983

NASA Technical Reports Server (NTRS)

Moffat, R. J.; Kays, W. M.

1984-01-01

For the past 25 years, there has existed in the Thermosciences Laboratory of the Mechanical Engineering Department of Stanford University a research program, primarily experimental, concerned with heat transfer through turbulent boundary layers. In the early phases of the program, the topics considered were the simple zero-pressure-gradient turbulent boundary layer with constant and with varying surface temperature, and the accelerated boundary layer. Later equilibrium boundary layers were considered along with factors affecting the boundary layer, taking into account transpired flows, flows with axial pressure gradients, transpiration, acceleration, deceleration, roughness, full-coverage film cooling, surface curvature, free convection, and mixed convection. A description is provided of the apparatus and techniques used, giving attention to the smooth plate rig, the rough plate rig, the full-coverage film cooling rig, the curvature rig, the concave wall rig, the mixed convection tunnel, and aspects of data reduction and uncertainty analysis.

An Examination of Body Temperature for the Rocky Intertidal Mussel species, Mytilus californianus, Using Remotely Sensed Satellite Observations

NASA Astrophysics Data System (ADS)

Price, J.; Liff, H.; Lakshmi, V.

2012-12-01

Temperature is considered to be one of the most important physical factors in determining organismal distribution and physiological performance of species in rocky intertidal ecosystems, especially the growth and survival of mussels. However, little is known about the spatial and temporal patterns of temperature in intertidal ecosystems or how those patterns affect intertidal mussel species because of limitations in data collection. We collected in situ temperature at Strawberry Hill, Oregon USA using mussel loggers embedded among the intertidal mussel species, Mytilus californianus. Remotely sensed surface temperatures were used in conjunction with in situ weather and ocean data to determine if remotely sensed surface temperatures can be used as a predictor for changes in the body temperature of a rocky intertidal mussel species. The data used in this study was collected between January 2003 and December 2010. The mussel logger temperatures were compared to in situ weather data collected from a local weather station, ocean data collected from a NOAA buoy, and remotely sensed surface temperatures collected from NASA's sun-synchronous Moderate Resolution Imaging Spectroradiometer aboard the Earth Observing System Aqua and EOS Terra satellites. Daily surface temperatures were collected from four pixel locations which included two sea surface temperature (SST) locations and two land surface temperature (LST) locations. One of the land pixels was chosen to represent the intertidal surface temperature (IST) because it was located within the intertidal zone. As expected, all surface temperatures collected via satellite were significantly correlated to each other and the associated in situ temperatures. Examination of temperatures from the off-shore NOAA buoy and the weather station provide evidence that remotely sensed temperatures were similar to in situ temperature data and explain more variability in mussel logger temperatures than the in situ temperatures. Our results suggest that temperatures (surface temperature and air temperature) are similar across larger spatial scales even when the type of data collection is different. Mussel logger temperatures were strongly correlated to SSTs and were not significantly different than SSTs. Sea surface temperature collected during the Aqua overpass explained 67.1% of the variation in mean monthly mussel logger temperature. When SST, LST, and IST were taken into consideration, nearly 73% of the variation in mussel logger temperature was explained. While in situ monthly air temperature and water temperature explained only 28-33% of the variation in mussel logger temperature. Our results suggests that remotely sensed surface temperatures are reliable and important measurements that can be used to better understand the effects temperature may have on intertidal mussel species in Strawberry Hill, Oregon. Remotely sensed surface temperature could act as a relative indicator of change and may be used to predict general habitat trends and drivers that could directly affect organism body temperature.

Hummingbird Comet Nucleus Analysis Mission

NASA Technical Reports Server (NTRS)

Kojiro, Daniel; Carle, Glenn C.; Lasher, Larry E.

2000-01-01

Hummingbird is a highly focused scientific mission, proposed to NASA s Discovery Program, designed to address the highest priority questions in cometary science-that of the chemical composition of the cometary nucleus. After rendezvous with the comet, Hummingbird would first methodically image and map the comet, then collect and analyze dust, ice and gases from the cometary atmosphere to enrich characterization of the comet and support landing site selection. Then, like its namesake, Hummingbird would carefully descend to a pre-selected surface site obtaining a high-resolution image, gather a surface material sample, acquire surface temperature and then immediately return to orbit for detailed chemical and elemental analyses followed by a high resolution post-sampling image of the site. Hummingbird s analytical laboratory contains instrumentation for a comprehensive molecular and elemental analysis of the cometary nucleus as well as an innovative surface sample acquisition device.

The relationship between surface temperature, tissue temperature, microbubble formation, and steam pops.

PubMed

Thompson, Nathaniel; Lustgarten, Daniel; Mason, Bryan; Mueller, Enkhtuyaa; Calame, James; Bell, Stephen; Spector, Peter

2009-07-01

It has been proposed that microbubble (MB) monitoring can be used to safely titrate radiofrequency (RF) power. However, MB formation has been found to be an insensitive indicator of tissue temperature during RF delivery. We hypothesized that MB formation corresponds to surface-not tissue--temperature, and therefore would be an insensitive predictor of steam pops. An in vitro bovine heart model was used to measure surface and tissue temperatures during RF delivery under conditions designed to cause steam pops. Sensitivity of type II MB (MBII) formation as a predictor of steam pops and for surface temperatures more than 80 degrees C was calculated. Of 105 lesions delivered, 99 steam pops occurred. Twenty-one steam pops were preceded by MBII. MBII were seen in 26 lesions, five of which were not associated with steam pop. Surface temperature at onset of MBII was 87 +/- 9 degrees C versus a tissue temperature of 78 +/- 23 degrees C (P = 0.044). Surface temperature at the time of steam pops was 71 +/- 17 degrees C versus a tissue temperature of 102 +/- 17 degrees C (P < 0.0001). The sensitivity of MBII for steam pops was 21%, and 58% for detecting surface temperature in excess of 80 degrees C. MBII correlated better with surface temperature than with tissue temperature; steam pops, on the other hand, correlated better with tissue temperature. MBII was an insensitive marker of steam pops and surface temperature in excess of 80 degrees C. Therefore, MBII should not be used to titrate RF power.

Active radiometer for self-calibrated furnace temperature measurements

DOEpatents

Woskov, Paul P.; Cohn, Daniel R.; Titus, Charles H.; Wittle, J. Kenneth; Surma, Jeffrey E.

1996-01-01

Radiometer with a probe beam superimposed on its field-of-view for furnace temperature measurements. The radiometer includes a heterodyne millimeter/submillimeter-wave receiver including a millimeter/submillimeter-wave source for probing. The receiver is adapted to receive radiation from a surface whose temperature is to be measured. The radiation includes a surface emission portion and a surface reflection portion which includes the probe beam energy reflected from the surface. The surface emission portion is related to the surface temperature and the surface reflection portion is related to the emissivity of the surface. The simultaneous measurement of surface emissivity serves as a real time calibration of the temperature measurement.

The formation of diethyl ether via the reaction of iodoethane with atomic oxygen on the Ag(110) surface

NASA Astrophysics Data System (ADS)

Jones, G. Scott; Barteau, Mark A.; Vohs, John M.

1999-01-01

The reactions of iodoethane (ICH 2CH 3) on clean and oxygen-covered Ag(110) surfaces were investigated using temperature-programmed desorption (TPD) and high-resolution electron energy-loss spectroscopy (HREELS). Iodoethane adsorbs dissociatively at 150 K to produce surface ethyl groups on both clean and oxygen-covered Ag(110) surfaces. The ethyl species couple to form butane on both surfaces, with the desorption peak maximum located between 218 and 238 K, depending on the ethyl coverage. In addition to butane, a number of oxidation products including diethyl ether, ethanol, acetaldehyde, surface acetate, ethylene, carbon dioxide and water were formed on the oxygen-dosed Ag(110) surface. Diethyl ether was the major oxygenate produced at all ethyl:oxygen ratios, and the peak temperature for ether evolution varied from 220 to 266 K depending on the relative coverages of these reactants. The total combustion products, CO 2 and H 2O, were primarily formed at low ethyl coverages in the presence of excess oxygen. The formation of ethylene near 240 K probably involves an oxygen-assisted dehydrogenation pathway since ethylene is not formed from ethyl groups on the clean surface. Acetaldehyde and ethanol evolve coincidentally with a peak centered at 270-280 K, and are attributed to the reactions of surface ethoxide species. The surface acetate which decomposes near 620 K is formed from subsequent reactions of acetaldehyde with oxygen atoms. The addition of ethyl to oxygen to form surface ethoxides was verified by HREELS results. The yields of all products exhibited a strong dependence on the relative coverages of ethyl and oxygen.

HNS/Teflon, a new heat resistant explosive

NASA Technical Reports Server (NTRS)

Heller, H.; Bertram, A. L.

1973-01-01

HNS/Teflon (90/10) is a new pressed explosive developed for use in the Apollo program. The major advantages of HNS/Teflon are (1) excellent thermal stability at elevated temperatures, (2) superior resistance to sublimation at high temperatures and low pressures and (3) ease of molding powder preparation, pressing and machining. The impact sensitivity of HNS/Teflon is between that of Comp B and Comp A-3 while its explosive performance is about the same as TNT. Under the severe environmental conditions of the moon's surface, this explosive successfully performed its intended function of generating seismic waves in the Apollo ALSEP and LSPE experiments. (Modified author abstract)

Radiant Heat Transfer in Reusable Surface Insulation

NASA Technical Reports Server (NTRS)

Hughes, T. A.; Linford, R. M. F.; Chmitt, R. J.; Christensen, H. E.

1973-01-01

During radiant testing of mullite panels, temperatures in the insulation and support structure exceeded those predicted on the basis of guarded hot plate thermal conductivity tests. Similar results were obtained during arc tunnel tests of mullite specimens. The differences between effective conductivity and guarded hot plate values suggested that radiant transfer through the mullite was occurring. To study the radiant transport, measurements were made of the infrared transmission through various insulating materials and fibers of interest to the shuttle program, using black body sources over the range of 780 to 2000 K. Experimental data were analyzed and scattering coefficients were derived for a variety of materials, fiber diameters, and source temperature.

Introduction: Historical perspective on the HCMM program

NASA Technical Reports Server (NTRS)

1982-01-01

When some thermal radiation sensitive devices on U.S. meteorological satellites generated low resolution images showing temperature variations on Earth's land and sea surfaces during the middle 1960's, interest was aroused in the potential of thermal sensing in geology, agriculture, soil moisture, ground water, water temperature, and vegetation applications. The concept of using the property of thermal inertia to identify materials, particularly those of a geologic nature can be traced to the same time period that marks the flight of the first LANDSAT - Spacecraft systems and their performance, and capabilities are reviewed as well as achievements in hydrology, geology, agriculture, pedology, and urban climate effects applications.

COI oxidation on a single Pd atom supported on magnesia.

PubMed

Abbet, S; Heiz, U; Häkkinen, H; Landman, U

2001-06-25

The oxidation of CO on single Pd atoms anchored to MgO(100) surface oxygen vacancies is studied with temperature-programmed-reaction mass spectrometry and infrared spectroscopy. In one-heating-cycle experiments, CO(2), formed from O(2) and CO preadsorbed at 90 K, is detected at 260 and 500 K. Ab-initio simulations suggest two reaction routes, with Pd(CO)(2)O(2) and PdCO(3)CO found as precursors for the low and high temperature channels, respectively. Both reactions result in annealing of the vacancy and induce migration and coalescence of the remaining Pd-CO to form larger clusters.

SubductionGenerator: A program to build three-dimensional plate configurations

NASA Astrophysics Data System (ADS)

Jadamec, M. A.; Kreylos, O.; Billen, M. I.; Turcotte, D. L.; Knepley, M.

2016-12-01

Geologic, geochemical, and geophysical data from subduction zones indicate that a two-dimensional paradigm for plate tectonic boundaries is no longer adequate to explain the observations. Many open source software packages exist to simulate the viscous flow of the Earth, such as the dynamics of subduction. However, there are few open source programs that generate the three-dimensional model input. We present an open source software program, SubductionGenerator, that constructs the three-dimensional initial thermal structure and plate boundary structure. A 3D model mesh and tectonic configuration are constructed based on a user specified model domain, slab surface, seafloor age grid file, and shear zone surface. The initial 3D thermal structure for the plates and mantle within the model domain is then constructed using a series of libraries within the code that use a half-space cooling model, plate cooling model, and smoothing functions. The code maps the initial 3D thermal structure and the 3D plate interface onto the mesh nodes using a series of libraries including a k-d tree to increase efficiency. In this way, complicated geometries and multiple plates with variable thickness can be built onto a multi-resolution finite element mesh with a 3D thermal structure and 3D isotropic shear zones oriented at any angle with respect to the grid. SubductionGenerator is aimed at model set-ups more representative of the earth, which can be particularly challenging to construct. Examples include subduction zones where the physical attributes vary in space, such as slab dip and temperature, and overriding plate temperature and thickness. Thus, the program can been used to construct initial tectonic configurations for triple junctions and plate boundary corners.

Climatic Implications of the Observed Temperature Dependence of the Liquid Water Path of Low Clouds in the Southern Great Plains

NASA Technical Reports Server (NTRS)

DelGenio, Anthony

1999-01-01

Satellite observations of low-level clouds have challenged the assumption that adiabatic liquid water content combined with constant physical thickness will lead to a negative cloud optics feedback in a decadal climate change. We explore the reasons for the satellite results using four years of surface remote sensing data from the Atmospheric Radiation Measurement Program Cloud and Radiation Testbed site in the Southern Great Plains of the United States. We find that low cloud liquid water path is approximately invariant with temperature in winter but decreases strongly with temperature in summer, consistent with the satellite inferences at this latitude. This behavior occurs because liquid water content shows no detectable temperature dependence while cloud physical thickness decreases with warming. Thinning of clouds with warming is observed on seasonal, synoptic, and diurnal time scales; it is most obvious in the warm sectors of baroclinic waves. Although cloud top is observed to slightly descend with warming, the primary cause of thinning, is the ascent of cloud base due to the reduction in surface relative humidity and the concomitant increase in the lifting condensation level of surface air. Low cloud liquid water path is not observed to be a continuous function of temperature. Rather, the behavior we observe is best explained as a transition in the frequency of occurrence of different boundary layer types. At cold temperatures, a mixture of stratified and convective boundary layers is observed, leading to a broad distribution of liquid water path values, while at warm temperatures, only convective boundary layers with small liquid water paths, some of them decoupled, are observed. Our results, combined with the earlier satellite inferences, imply that the commonly quoted 1.5C lower limit for the equilibrium global climate sensitivity to a doubling of CO2 which is based on models with near-adiabatic liquid water behavior and constant physical thickness, should be revised upward.

Climatic Implications of the Observed Temperature Dependence of the Liquid Water Path of Low Clouds in the Southern Great Plains

NASA Technical Reports Server (NTRS)

DelGenio, Anthony D.; Wolf, Audrey B.

1999-01-01

Satellite observations of low-level clouds have challenged the assumption that adiabatic liquid water content combined with constant physical thickness will lead to a negative cloud optics feedback in a decadal climate change. We explore the reasons for the satellite results using four years of surface remote sensing data from the Atmospheric Radiation Measurement Program Cloud and Radiation Testbed site in the Southern Great Plains of the United States. We find that low cloud liquid water path is approximately invariant with temperature in winter but decreases strongly with temperature in summer, consistent with the satellite inferences at this latitude. This behavior occurs because liquid water content shows no detectable temperature dependence while cloud physical thickness decreases with warming. Thinning of clouds with warming is observed on seasonal, synoptic, and diurnal time scales; it is most obvious in the warm sectors of baroclinic waves. Although cloud top is observed to slightly descend with warming, the primary cause of thinning is the ascent of cloud base due to the reduction in surface relative humidity and the concomitant increase in the lifting condensation level of surface air. Low cloud liquid water path is not observed to be a continuous function of temperature. Rather, the behavior we observe is best explained as a transition in the frequency of occurrence of different boundary layer types: At cold temperatures, a mixture of stratified and convective boundary layers is observed, leading to a broad distribution of liquid water path values, while at warm temperatures, only convective boundary layers with small liquid water paths, some of them decoupled, are observed. Our results, combined with the earlier satellite inferences, imply that the commonly quoted 1.50 C lower limit for the equilibrium global climate sensitivity to a doubling of CO2, which is based on models with near-adiabatic liquid water behavior and constant physical thickness, should be revised upward.

Assimilation of Surface Temperature in Land Surface Models

NASA Technical Reports Server (NTRS)

Lakshmi, Venkataraman

1998-01-01

Hydrological models have been calibrated and validated using catchment streamflows. However, using a point measurement does not guarantee correct spatial distribution of model computed heat fluxes, soil moisture and surface temperatures. With the advent of satellites in the late 70s, surface temperature is being measured two to four times a day from various satellite sensors and different platforms. The purpose of this paper is to demonstrate use of satellite surface temperature in (a) validation of model computed surface temperatures and (b) assimilation of satellite surface temperatures into a hydrological model in order to improve the prediction accuracy of soil moistures and heat fluxes. The assimilation is carried out by comparing the satellite and the model produced surface temperatures and setting the "true"temperature midway between the two values. Based on this "true" surface temperature, the physical relationships of water and energy balance are used to reset the other variables. This is a case of nudging the water and energy balance variables so that they are consistent with each other and the true" surface temperature. The potential of this assimilation scheme is demonstrated in the form of various experiments that highlight the various aspects. This study is carried over the Red-Arkansas basin in the southern United States (a 5 deg X 10 deg area) over a time period of a year (August 1987 - July 1988). The land surface hydrological model is run on an hourly time step. The results show that satellite surface temperature assimilation improves the accuracy of the computed surface soil moisture remarkably.

Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Inspection of the Engineering Condition of Underwater Concrete Structures.

DTIC Science & Technology

1989-04-01

corrosion of rebar Spalling of concrete surface IIl Detect hidden and beginning Location of rebar damage Beginning corrosion of rebar ...honeycombs MD Moderate defects: spalling of concrete minor corrosion of exposed rebar rust stains along rebar with or without visible cracking softening of...velocity. . Replenishment of the attacking chemical hgents. h. Higher temperatures. i. Corrosion of reinforcing steel. 46. Note that concrete which

A Survey of Road Construction and Maintenance Problems in Central Alaska.

DTIC Science & Technology

1976-10-01

recent natural disasters, such as the earthquake of 1964 and the Fairbanks flood in 1967, seriously set back the Alaskan highway program for several...problems as classifica- tion of natural road building materials, prevention of culvert icing, measurement of subgrade temperature, maintenance of slopes...Scarcity of clays or other material suitable for use as a binder in gravel surfacings poses additional problems throughout Alaska. Dust and stones

Recent Weather Extremes and Impacts on Agricultural Production and Vector-Borne Disease Outbreak Patterns

DTIC Science & Technology

2014-03-21

funding from USDA Foreign Agricultural Service towards the Global Agricultural Monitoring project, DoD Armed Forces Health Surveillance Center’s...Global Emerging Infections Surveillance and Response System (AFHSC/GEIS) under the Human Febrile and Vector -Borne Illnesses (FVBI) Program and USDA ...outbreaks during the 2010?2012 period. We utilized 2000?2012 vegetation index and land surface temperature data from NASA ?s satellitebased Moderate

The Seasat commercial demonstration program

NASA Technical Reports Server (NTRS)

Mccandless, S. W.; Miller, B. P.; Montgomery, D. R.

1981-01-01

The background and development of the Seasat commercial demonstration program are reviewed and the Seasat spacecraft and its sensors (altimeter, wind field scatterometer, synthetic aperture radar, and scanning multichannel microwave radiometer) are described. The satellite data distribution system allows for selected sets of data, reformatted or tailored to specific needs and geographical regions, to be available to commercial users. Products include sea level and upper atmospheric pressure, sea surface temperature, marine winds, significant wave heights, primary wave direction and period, and spectral wave data. The results of a set of retrospective case studies performed for the commercial demonstration program are described. These are in areas of application such as marine weather and ocean condition forecasting, offshore resource exploration and development, commercial fishing, and marine transportation.

Temperature measurement involving nanostructured thermal barrier coating using a multiwavelength pyrometer

NASA Technical Reports Server (NTRS)

Ng, Daniel

1996-01-01

It has been reported that erroneous results were obtained when a conventional pyrometer was used to measure the surface temperature of turbine engine components. Temperatures discrepancies were observed in components which were identical, except that one had its measured surface covered by a nanostructured thermal barrier coating (TBC) whereas the other component's surface was not so coated. These components were placed in an identical environment, receiving identical heat fluxes. A pyrometer measured the TBC covered surface hundreds degrees lower. These coatings were about 25 (mu)m thick, consisting of hundreds of layers of finer structures. The TBC's had very low thermal conductivity, heat flux calculations indicated that the temperatures of the coated surface should exhibit much higher temperature than the uncoated surface. Because these coatings were transparent to radiation from the visible to the infrared region, the temperatures measured by the pyrometer should be the temperature of the covered surface. Turbo components' performance and service life depend critically on the temperatures that it would experience; it is therefore important to know accurately and confidently the real surface temperature. Out of these concerns, an investigation into the measurement of nanostructured material surface temperature was carried out.

Estimation of Surface Heat Flux and Surface Temperature during Inverse Heat Conduction under Varying Spray Parameters and Sample Initial Temperature

PubMed Central

Aamir, Muhammad; Liao, Qiang; Zhu, Xun; Aqeel-ur-Rehman; Wang, Hong

2014-01-01

An experimental study was carried out to investigate the effects of inlet pressure, sample thickness, initial sample temperature, and temperature sensor location on the surface heat flux, surface temperature, and surface ultrafast cooling rate using stainless steel samples of diameter 27 mm and thickness (mm) 8.5, 13, 17.5, and 22, respectively. Inlet pressure was varied from 0.2 MPa to 1.8 MPa, while sample initial temperature varied from 600°C to 900°C. Beck's sequential function specification method was utilized to estimate surface heat flux and surface temperature. Inlet pressure has a positive effect on surface heat flux (SHF) within a critical value of pressure. Thickness of the sample affects the maximum achieved SHF negatively. Surface heat flux as high as 0.4024 MW/m2 was estimated for a thickness of 8.5 mm. Insulation effects of vapor film become apparent in the sample initial temperature range of 900°C causing reduction in surface heat flux and cooling rate of the sample. A sensor location near to quenched surface is found to be a better choice to visualize the effects of spray parameters on surface heat flux and surface temperature. Cooling rate showed a profound increase for an inlet pressure of 0.8 MPa. PMID:24977219

Comet 67P: Thermal Maps and Local Properties as Derived from Rosetta/VIRTIS data

NASA Astrophysics Data System (ADS)

Tosi, Federico; Capria, Maria Teresa; Capaccioni, Fabrizio; Filacchione, Gianrico; Erard, Stéphane; Leyrat, Cédric; Bockelée-Morvan, Dominique; De Sanctis, Maria Cristina; Raponi, Andrea; Ciarniello, Mauro; Schmitt, Bernard; Arnold, Gabriele; Mottola, Stefano; Fonti, Sergio; Palomba, Ernesto; Longobardo, Andrea; Cerroni, Priscilla; Piccioni, Giuseppe; Drossart, Pierre; Kuehrt, Ekkehard

2015-04-01

Comet 67P is shown to be everywhere rich in organic materials with little to no water ice visible on the surface. In the range of heliocentric distances from 3.59 to 2.74 AU, daytime observed surface temperatures retrieved from VIRTIS data are overall comprised in the range between 180 and 220 K, which is incompatible with large exposures of water ice and is consistent with a low-albedo, organics-rich surface. The accuracy of temperature retrieval is as good as a few K in regions of the comet unaffected by shadowing or limb proximity. Maximum temperature values as high as 230 K have been recorded in very few places. The highest values of surface temperature in the early Mapping phase were obtained in August 2014, during observations at small phase angles implying that the observed surface has a large predominance of small incidence angles, and local solar times (LST) centered around the maximum daily insolation. In all cases, direct correlation with topographic features is observed, i.e. largest temperature values are generally associated with the smallest values of illumination angles. So far, there is no evidence of thermal anomalies, i.e. places of the surface that are intrinsically warmer or cooler than surrounding terrains observed at the same local solar time and under similar solar illumination. For a given LST, the maximum temperature mainly depends on the solar incidence angle and on surface properties such as thermal inertia and albedo. Since VIRTIS is able to observe the same point of the surface on various occasions under different conditions of solar illumination and LST, it is possible to reconstruct the temperature of that point at different times of the comet's day, thus building diurnal profiles of temperature that are useful to constrain thermal inertia. The availability of spatially-resolved, accurate temperature observations, significantly spaced out in local solar time, provides clues to the physical structure local features, which complements the compositional investigation based on imaging spectroscopy data collected at shorter wavelengths. In the VIRTIS thermal images, a note of great interest is provided by the 'neck' of the comet close to the 'body', where, because of the concave shape, the 'head' casts prominent shadows on some areas when they experience maximum daily insolation. This is a place potentially subjected to considerable thermal stresses. We evaluate both the spatial thermal gradients and the temporal thermal gradients, providing implications for the surface structure. Acknowledgements: The authors would like to thank the following institutions and agencies, which supported this work: Italian Space Agency (ASI - Italy), Centre National d'Etudes Spatiales (CNES- France), Deutsches Zentrum für Luft- und Raumfahrt (DLR-Germany), National Aeronautic and Space Administration (NASA-USA) Rosetta Program, Science and Technology Facilities Council (UK). VIRTIS has been built by a consortium, which includes Italy, France and Germany, under the scientific responsibility of the Istituto di Astrofisica e Planetologia Spaziali of INAF, Italy, which guides also the scientific operations. The VIRTIS instrument development has been funded and managed by ASI, with contributions from Observatoire de Meudon financed by CNES, and from DLR. The computational resources used in this research have been supplied by INAF-IAPS through the DataWell project.

Characterizing superconducting thin films using AC Magnetic Susceptibility

NASA Astrophysics Data System (ADS)

Mahoney, C. H.; Porzio, J.; Sullivan, M. C.

2014-03-01

We present our work on using ac magnetic susceptibility to determine the critical temperature of superconducting thin films. In ac magnetic susceptibility, the thin film is placed between two coils. One coil carries an ac signal, creating a varying external magnetic field. We measure the voltage induced in the pick-up coil on the opposite side of the sample and measure how the sample magnetization changes as the temperature changes. We will present our work to use ac susceptibility to determine critical temperature and superconducting volume fraction. Using our own analysis program, we are able to accurately locate the critical temperatures of the samples and determine the transition width. For the superconducting volume fraction, we etch samples in order to control the thicknesses of the sample and measure how much of the material grown on the surface is superconducting. Supported by NFS grant DMR-1305637.

Thermal Model of a Current-Carrying Wire in a Vacuum

NASA Technical Reports Server (NTRS)

Border, James

2006-01-01

A computer program implements a thermal model of an insulated wire carrying electric current and surrounded by a vacuum. The model includes the effects of Joule heating, conduction of heat along the wire, and radiation of heat from the outer surface of the insulation on the wire. The model takes account of the temperature dependences of the thermal and electrical properties of the wire, the emissivity of the insulation, and the possibility that not only can temperature vary along the wire but, in addition, the ends of the wire can be thermally grounded at different temperatures. The resulting second-order differential equation for the steady-state temperature as a function of position along the wire is highly nonlinear. The wire is discretized along its length, and the equation is solved numerically by use of an iterative algorithm that utilizes a multidimensional version of the Newton-Raphson method.

High temperature aircraft research furnace facilities

NASA Technical Reports Server (NTRS)

Smith, James E., Jr.; Cashon, John L.

1992-01-01

Focus is on the design, fabrication, and development of the High Temperature Aircraft Research Furnace Facilities (HTARFF). The HTARFF was developed to process electrically conductive materials with high melting points in a low gravity environment. The basic principle of operation is to accurately translate a high temperature arc-plasma gas front as it orbits around a cylindrical sample, thereby making it possible to precisely traverse the entire surface of a sample. The furnace utilizes the gas-tungsten-arc-welding (GTAW) process, also commonly referred to as Tungsten-Inert-Gas (TIG). The HTARFF was developed to further research efforts in the areas of directional solidification, float-zone processing, welding in a low-gravity environment, and segregation effects in metals. The furnace is intended for use aboard the NASA-JSC Reduced Gravity Program KC-135A Aircraft.

Heating 7.2 user`s manual

DOE Office of Scientific and Technical Information (OSTI.GOV)

Childs, K.W.

1993-02-01

HEATING is a general-purpose conduction heat transfer program written in Fortran 77. HEATING can solve steady-state and/or transient heat conduction problems in one-, two-, or three-dimensional Cartesian, cylindrical, or spherical coordinates. A model may include multiple materials, and the thermal conductivity, density, and specific heat of each material may be both time- and temperature-dependent. The thermal conductivity may also be anisotropic. Materials may undergo change of phase. Thermal properties of materials may be input or may be extracted from a material properties library. Heat-generation rates may be dependent on time, temperature, and position, and boundary temperatures may be time- andmore » position-dependent. The boundary conditions, which may be surface-to-environment or surface-to-surface, may be specified temperatures or any combination of prescribed heat flux, forced convection, natural convection, and radiation. The boundary condition parameters may be time- and/or temperature-dependent. General gray-body radiation problems may be modeled with user-defined factors for radiant exchange. The mesh spacing may be variable along each axis. HEATING uses a runtime memory allocation scheme to avoid having to recompile to match memory requirements for each specific problem. HEATING utilizes free-form input. Three steady-state solution techniques are available: point-successive-overrelaxation iterative method with extrapolation, direct-solution, and conjugate gradient. Transient problems may be solved using any one of several finite-difference schemes: Crank-Nicolson implicit, Classical Implicit Procedure (CIP), Classical Explicit Procedure (CEP), or Levy explicit method. The solution of the system of equations arising from the implicit techniques is accomplished by point-successive-overrelaxation iteration and includes procedures to estimate the optimum acceleration parameter.« less

Heating 7. 2 user's manual

DOE Office of Scientific and Technical Information (OSTI.GOV)

Childs, K.W.

1993-02-01

HEATING is a general-purpose conduction heat transfer program written in Fortran 77. HEATING can solve steady-state and/or transient heat conduction problems in one-, two-, or three-dimensional Cartesian, cylindrical, or spherical coordinates. A model may include multiple materials, and the thermal conductivity, density, and specific heat of each material may be both time- and temperature-dependent. The thermal conductivity may also be anisotropic. Materials may undergo change of phase. Thermal properties of materials may be input or may be extracted from a material properties library. Heat-generation rates may be dependent on time, temperature, and position, and boundary temperatures may be time- andmore » position-dependent. The boundary conditions, which may be surface-to-environment or surface-to-surface, may be specified temperatures or any combination of prescribed heat flux, forced convection, natural convection, and radiation. The boundary condition parameters may be time- and/or temperature-dependent. General gray-body radiation problems may be modeled with user-defined factors for radiant exchange. The mesh spacing may be variable along each axis. HEATING uses a runtime memory allocation scheme to avoid having to recompile to match memory requirements for each specific problem. HEATING utilizes free-form input. Three steady-state solution techniques are available: point-successive-overrelaxation iterative method with extrapolation, direct-solution, and conjugate gradient. Transient problems may be solved using any one of several finite-difference schemes: Crank-Nicolson implicit, Classical Implicit Procedure (CIP), Classical Explicit Procedure (CEP), or Levy explicit method. The solution of the system of equations arising from the implicit techniques is accomplished by point-successive-overrelaxation iteration and includes procedures to estimate the optimum acceleration parameter.« less

Do Aphids Alter Leaf Surface Temperature Patterns During Early Infestation?

PubMed Central

Cahon, Thomas; Caillon, Robin

2018-01-01

Arthropods at the surface of plants live in particular microclimatic conditions that can differ from atmospheric conditions. The temperature of plant leaves can deviate from air temperature, and leaf temperature influences the eco-physiology of small insects. The activity of insects feeding on leaf tissues, may, however, induce changes in leaf surface temperatures, but this effect was only rarely demonstrated. Using thermography analysis of leaf surfaces under controlled environmental conditions, we quantified the impact of presence of apple green aphids on the temperature distribution of apple leaves during early infestation. Aphids induced a slight change in leaf surface temperature patterns after only three days of infestation, mostly due to the effect of aphids on the maximal temperature that can be found at the leaf surface. Aphids may induce stomatal closure, leading to a lower transpiration rate. This effect was local since aphids modified the configuration of the temperature distribution over leaf surfaces. Aphids were positioned at temperatures near the maximal leaf surface temperatures, thus potentially experiencing the thermal changes. The feedback effect of feeding activity by insects on their host plant can be important and should be quantified to better predict the response of phytophagous insects to environmental changes. PMID:29538342

PROJECT VeSElkA: ANALYSIS OF BALMER LINE PROFILES OF SLOWLY ROTATING CHEMICALLY PECULIAR STARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khalack, V.; LeBlanc, F., E-mail: khalack.viktor@umoncton.ca

2015-07-15

We present results for the estimation of gravity, effective temperature, and radial velocity of poorly studied chemically peculiar stars recently observed with the spectropolarimeter Echelle SpectroPolarimetric Device for Observations of Stars at the Canada–France–Hawaii Telescope in the frame of the Vertical Stratification of Element Abundances project. The effective temperature and surface gravity values are determined for the very first time for four of the stars from our sample (HD 23878, HD 83373, HD 95608, and HD 164584). Grids of stellar atmosphere models with the corresponding fluxes have been calculated using version 15 of the PHOENIX code for effective temperatures inmore » the range of 5000–15,000 K, for the logarithm of surface gravities in the range of 3.0–4.5 and for the metallicities from −1.0 to +1.5. We used these fluxes to fit the Balmer line profiles employing the code FITSB2 that produces estimates of the effective temperature, gravity, and radial velocity for each star. When possible, our results are compared to those previously published. The physical characteristics of 16 program stars are discussed with the future aim to study the abundance anomalies of chemical species and the possible vertical abundance stratification in their stellar atmosphere.« less

Effects of silver and group II fluoride solid lubricant additions to plasma-sprayed chromium carbide coatings for foil gas bearings to 650 C

NASA Technical Reports Server (NTRS)

Wagner, R. C.; Sliney, Harold E.

1986-01-01

A new self-lubricating coating composition of nickel aluminide-bonded chromium carbide formulated with silver and Group II fluorides was developed in a research program on high temperature solid lubricants. One of the proposed applications for this new coating composition is as a wide temperature spectrum solid lubricant for complaint foil gas bearings. Friction and wear properties were obtained using a foil gas bearing start-stop apparatus at temperatures from 25 to 650 C. The journals were Inconel 748. Some were coated with the plasma sprayed experimental coating, others with unmodified nickel aluminide/chromium carbide as a baseline for comparison. The additional components were provided to assist in achieving low friction over the temperature range of interest. Uncoated, preoxidized Inconel X-750 foil bearings were operated against these surfaces. The foils were subjected to repeated start/stop cycles under a 14-kPa (2-Psi) bearing unit loading. Sliding contact occurred during lift-off and coastdown at surface velocities less than 6 m/s (3000 rPm). Testing continued until 9000 start/stop cycles were accumulated or until a rise in starting torque indicated the journal/bearing had failed. Comparison in coating performance as well as discussions of their properties and methods of application are given.

Areas of Weakly Anomalous to Anomalous Surface Temperature in Chaffee County, Colorado, as Identified from ASTER Thermal Data

DOE Data Explorer

Khalid Hussein

2012-02-01

Note: This "Weakly Anomalous to Anomalous Surface Temperature" dataset differs from the "Anomalous Surface Temperature" dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1o and 2o above the mean, as opposed to the greater than 2o temperatures contained in the "Anomalous Surface Temperature" dataset. This layer contains areas of anomalous surface temperature in Chaffee County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature greater than 2o were considered ASTER modeled very warm surface exposures (thermal anomalies). Note: 'o' is used in this description to represent lowercase sigma.

Areas of Weakly Anomalous to Anomalous Surface Temperature in Garfield County, Colorado, as Identified from ASTER Thermal Data

DOE Data Explorer

Khalid Hussein

2012-02-01

Note: This "Weakly Anomalous to Anomalous Surface Temperature" dataset differs from the "Anomalous Surface Temperature" dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1o and 2o above the mean, as opposed to the greater than 2o temperatures contained in the "Anomalous Surface Temperature" dataset. This layer contains areas of anomalous surface temperature in Garfield County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature between 1o and 2o were considered ASTER modeled warm surface exposures (thermal anomalies) Note: 'o' is used in this description to represent lowercase sigma.

Areas of Weakly Anomalous to Anomalous Surface Temperature in Routt County, Colorado, as Identified from ASTER Thermal Data

DOE Data Explorer

Khalid Hussein

2012-02-01

Note: This "Weakly Anomalous to Anomalous Surface Temperature" dataset differs from the "Anomalous Surface Temperature" dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1o and 2o above the mean, as opposed to the greater than 2o temperatures contained in the "Anomalous Surface Temperature" dataset. This layer contains areas of anomalous surface temperature in Routt County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature between 1o and 2o were considered ASTER modeled warm surface exposures (thermal anomalies). Note: 'o' is used in this description to represent lowercase sigma.

Areas of Weakly Anomalous to Anomalous Surface Temperature in Dolores County, Colorado, as Identified from ASTER Thermal Data

DOE Data Explorer

Khalid Hussein

2012-02-01

Note: This "Weakly Anomalous to Anomalous Surface Temperature" dataset differs from the "Anomalous Surface Temperature" dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1o and 2o above the mean, as opposed to the greater than 2o temperatures contained in the "Anomalous Surface Temperature" dataset. This layer contains areas of anomalous surface temperature in Dolores County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature greater than 2o were considered ASTER modeled very warm surface exposures (thermal anomalies) Note: 'o' is used in this description to represent lowercase sigma.

Areas of Weakly Anomalous to Anomalous Surface Temperature in Archuleta County, Colorado, as Identified from ASTER Thermal Data

DOE Data Explorer

Khalid Hussein

2012-02-01

Note: This "Weakly Anomalous to Anomalous Surface Temperature" dataset differs from the "Anomalous Surface Temperature" dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1o and 2o above the mean, as opposed to the greater than 2o temperatures contained in the "Anomalous Surface Temperature" dataset. This layer contains areas of anomalous surface temperature in Archuleta County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature between 1o and 2o were considered ASTER modeled warm surface exposures (thermal anomalies). Note: 'o' is used in this description to represent lowercase sigma.

Active radiometer for self-calibrated furnace temperature measurements

DOEpatents

Woskov, P.P.; Cohn, D.R.; Titus, C.H.; Wittle, J.K.; Surma, J.E.

1996-11-12

A radiometer is described with a probe beam superimposed on its field-of-view for furnace temperature measurements. The radiometer includes a heterodyne millimeter/submillimeter-wave receiver including a millimeter/submillimeter-wave source for probing. The receiver is adapted to receive radiation from a surface whose temperature is to be measured. The radiation includes a surface emission portion and a surface reflection portion which includes the probe beam energy reflected from the surface. The surface emission portion is related to the surface temperature and the surface reflection portion is related to the emissivity of the surface. The simultaneous measurement of surface emissivity serves as a real time calibration of the temperature measurement. 5 figs.

Heterogeneity of soil surface temperature induced by xerophytic shrub in a revegetated desert ecosystem, northwestern China

NASA Astrophysics Data System (ADS)

Zhang, Ya-Feng; Wang, Xin-Ping; Pan, Yan-Xia; Hu, Rui; Zhang, Hao

2013-06-01

Variation characteristics of the soil surface temperature induced by shrub canopy greatly affects the near-surface biological and biochemical processes in desert ecosystems. However, information regarding the effects of shrub upon the heterogeneity of soil surface temperature is scarce. Here we aimed to characterize the effects of shrub ( Caragana korshinskii) canopy on the soil surface temperature heterogeneity at areas under shrub canopy and the neighbouring bare ground. Diurnal variations of soil surface temperature were measured at areas adjacent to the shrub base (ASB), beneath the midcanopy (BMC), and in the bare intershrub spaces (BIS) at the eastern, southern, western and northern aspects of shrub, respectively. Results indicated that diurnal mean soil surface temperature under the C. korshinskii canopy (ASB and BMC) was significantly lower than in the BIS, with the highest in the BIS, followed by the BMC and ASB. The diurnal maximum and diurnal variations of soil surface temperatures under canopy vary strongly with different aspects of shrub with the diurnal variation in solar altitude, which could be used as cues to detect safe sites for under-canopy biota. A significant empirical linear relationship was found between soil surface temperature and solar altitude, suggesting an empirical predicator that solar altitude can serve for soil surface temperature. Lower soil surface temperatures under the canopy than in the bare intershrub spaces imply that shrubs canopy play a role of `cool islands' in the daytime in terms of soil surface temperature during hot summer months in the desert ecosystems characterized by a mosaic of sparse vegetation and bare ground.

Preliminary study of temperature measurement techniques for Stirling engine reciprocating seals

NASA Technical Reports Server (NTRS)

Wilcock, D. F.; Hoogenboom, L.; Meinders, M.; Winer, W. O.

1981-01-01

Methods of determining the contact surface temperature in reciprocating seals are investigated. Direct infrared measurement of surface temperatures of a rod exiting a loaded cap seal or simulated seal are compared with surface thermocouple measurements. Significant cooling of the surface requires several milliseconds so that exit temperatures may be considered representative of internal contact temperatures.

Sorption of hydrogen by silica aerogel at low-temperatures

NASA Astrophysics Data System (ADS)

Dolbin, A. V.; Khlistyuck, M. V.; Esel'son, V. B.; Gavrilko, V. G.; Vinnikov, N. A.; Basnukaeva, R. M.; Martsenuk, V. E.; Veselova, N. V.; Kaliuzhnyi, I. A.; Storozhko, A. V.

2018-02-01

The programmed thermal desorption method is used at temperatures of 7-95 K to study the sorption and subsequent desorption of hydrogen by a sample of silica aerogel. Physical sorption of hydrogen owing to the weak van-der-Waals interaction of hydrogen molecules with the silicon dioxide walls of the pores of the sample was observed over the entire temperature range. The total capacity of the aerogel sample for hydrogen was ˜1.5 mass %. It was found that when the sample temperature was lowered from 95 to 60 K, the characteristic sorption times for hydrogen by the silica aerogel increase; this is typical of thermally activated diffusion (Ea ≈ 408 K). For temperatures of 15-45 K the characteristic H2 sorption times depended weakly on temperature, presumably because of the predominance of a tunnel mechanism for diffusion over thermally activated diffusion. Below 15 K the characteristic sorption times increase somewhat as the temperature is lowered; this may be explained by the formation of a monolayer of H2 molecules on the surface of the aerogel grains.

Inland Water Temperature: An Ideal Indicator for the National Climate Assessment

NASA Astrophysics Data System (ADS)

Hook, S. J.; Lenters, J. D.; O'Reilly, C.; Healey, N. C.

2014-12-01

NASA is a significant contributor to the U.S. National Climate Assessment (NCA), which is a central component of the 2012-2022 U.S. Global Change Research Program Strategic Plan. The NCA has identified the need for indicators that provide a clear, concise way of communicating to NCA audiences about not only the status and trends of physical drivers of the climate system, but also the ecological and socioeconomic impacts, vulnerabilities, and responses to those drivers. We are using thermal infrared satellite data in conjunction with in situ measurements to produce water temperatures for all the large inland water bodies in North America for potential use as an indicator for the NCA. Recent studies have revealed significant warming of inland waters throughout the world. The observed rate of warming is - in many cases - greater than that of the ambient air temperature. These rapid, unprecedented changes in inland water temperatures have profound implications for lake hydrodynamics, productivity, and biotic communities. Scientists are just beginning to understand the global extent, regional patterns, physical mechanisms, and ecological consequences of lake warming. As part of our earlier studies we have collected thermal infrared satellite data from those satellite sensors that provide long-term and frequent spaceborne thermal infrared measurements of inland waters including ATSR, AVHRR, and MODIS and used these to examine trends in water surface temperature for approximately 100 of the largest inland water bodies in the world. We are now extending this work to generate temperature time-series of all North American inland water bodies that are sufficiently large to be studied using 1km resolution satellite data for the last 3 decades. These data are then being related to changes in the surface air temperature and compared with regional trends in water surface temperature derived from CMIP5/IPCC model simulations/projections to better predict future temperature changes. This information is also being used to develop ecologically relevant indicators that are meaningful to the general public, and useful for the National Climate Assessment teams. We will discuss the available datasets and processing methodologies together with their potential use for climate assessment.

METEOSAT studies of clouds and radiation budget

NASA Technical Reports Server (NTRS)

Saunders, R. W.

1982-01-01

Radiation budget studies of the atmosphere/surface system from Meteosat, cloud parameter determination from space, and sea surface temperature measurements from TIROS N data are all described. This work was carried out on the interactive planetary image processing system (IPIPS), which allows interactive manipulationion of the image data in addition to the conventional computational tasks. The current hardware configuration of IPIPS is shown. The I(2)S is the principal interactive display allowing interaction via a trackball, four buttons under program control, or a touch tablet. Simple image processing operations such as contrast enhancing, pseudocoloring, histogram equalization, and multispectral combinations, can all be executed at the push of a button.

Shot peening for Ti-6Al-4V alloy compressor blades

NASA Technical Reports Server (NTRS)

Carek, Gerald A.

1987-01-01

A text program was conducted to determine the effects of certain shot-peening parameters on the fatigue life of the Ti-6Al-4V alloys as well as the effect of a demarcation line on a test specimen. This demarcation line, caused by an abrupt change from untreated surface to shot-peened surface, was thought to have caused the failure of several blades in a multistage compressor at the NASA Lewis Research Center. The demarcation line had no detrimental effect upon bending fatigue specimens tested at room temperature. Procedures for shot peening Ti-6Al-4V compressor blades are recommended for future applications.

An analytical and experimental evaluation of shadow shields and their support members

NASA Technical Reports Server (NTRS)

Stochl, R. J.; Boyle, R. J.

1972-01-01

Experimental tests were performed on a model shadow shield thermal protection system to examine the effect of certain configuration variables. The experimental results were used to verify the ability of an analytical program to predict the shadow shield performance including the shield-support interaction. In general, the analysis (assuming diffuse surfaces) agreed well with the experimental support temperature profiles. The agreement for the shield profiles was not as good. The results demonstrated: (1) shadow shields can be effective in reducing the heat transfer into cryogenic propellant tanks, and (2) the conductive heat transfer through supports can be reduced by selective surface coatings.

Comparison between AVHRR surface temperature data and in-situ weather station temperatures over the Greenland Ice Sheet

NASA Astrophysics Data System (ADS)

Rezvanbehbahani, S.; Csatho, B. M.; Comiso, J. C.; Babonis, G. S.

2011-12-01

Advanced Very-High Resolution Radiometer (AVHRR) images have been exhaustively used to measure surface temperature time series of the Greenland Ice sheet. The purpose of this study is to assess the accuracy of monthly average ice sheet surface temperatures, derived from thermal infrared AVHRR satellite imagery on a 6.25 km grid. In-situ temperature data sets are from the Greenland Collection Network (GC-Net). GC-Net stations comprise sensors monitoring air temperature at 1 and 2 meter above the snow surface, gathered at every 60 seconds and monthly averaged to match the AVHRR temporal resolution. Our preliminary results confirm the good agreement between satellite and in-situ temperature measurements reported by previous studies. However, some large discrepancies still exist. While AVHRR provides ice surface temperature, in-situ stations measure air temperatures at different elevations above the snow surface. Since most in-situ data on ice sheets are collected by Automatic Weather Station (AWS) instruments, it is important to characterize the difference between surface and air temperatures. Therefore, we compared and analyzed average monthly AVHRR ice surface temperatures using data collected in 2002. Differences between these temperatures correlate with in-situ temperatures and GC-Net station elevations, with increasing differences at lower elevations and higher temperatures. The Summit Station (3199 m above sea level) and the Swiss Camp (1176 m above sea level) results were compared as high altitude and low altitude stations for 2002, respectively. Our results show that AVHRR derived temperatures were 0.5°K warmer than AWS temperature at the Summit Station, while this difference was 2.8°K in the opposite direction for the Swiss Camp with surface temperatures being lower than air temperatures. The positive bias of 0.5°K at the high altitude Summit Station (surface warmer than air) is within the retrieval error of AVHRR temperatures and might be in part due to atmospheric inversion. The large negative bias of 2.8°K at the low altitude Swiss Camp (surface colder than the air) could be caused by a combination of different factors including local effects such as more windy circumstances above the snow surface and biases introduced by the cloud-masking applied on the AVHRR images. Usually only satellite images acquired in clear-sky conditions are used for deriving monthly AVHRR average temperatures. Since cloud-free days are usually warmer, satellite derived temperatures tend to underestimate the real average temperatures, especially regions with frequent cloud cover, such as Swiss Camp. Therefore, cautions must be exercised while using ice surface temperatures derived from satellite imagery for glaciological applications. Eliminating the cloudy day's' temperature from the in-situ data prior to the comparison with AVHRR derived temperatures will provide a better assessment of AVHRR surface temperature measurement accuracy.

Estimating the Longwave Radiation Underneath the Forest Canopy in Snow-dominated Setting

NASA Astrophysics Data System (ADS)

Zhou, Y.; Kumar, M.; Link, T. E.

2017-12-01

Forest canopies alter incoming longwave radiation at the land surface, thus influencing snow cover energetics. The snow surface receives longwave radiation from the sky as well as from surrounding vegetation. The longwave radiation from trees is determined by its skin temperature, which shows significant heterogeneity depending on its position and morphometric attributes. Here our goal is to derive an effective tree temperature that can be used to estimate the longwave radiation received by the land surface pixel. To this end, we implement these three steps: 1) derive a relation between tree trunk surface temperature and the incident longwave radiation, shortwave radiation, and air temperature; 2) develop an inverse model to calculate the effective temperature by establishing a relationship between the effective temperature and the actual tree temperature; and 3) estimate the effective temperature using widely measured variables, such as solar radiation and forest density. Data used to derive aforementioned relations were obtained at the University of Idaho Experimental Forest, in northern Idaho. Tree skin temperature, incoming longwave radiation, solar radiation received by the tree surface, and air temperature were measured at an isolated tree and a tree within a homogeneous forest stand. Longwave radiation received by the land surface and the sky view factors were also measured at the same two locations. The calculated effective temperature was then compared with the measured tree trunk surface temperature. Additional longwave radiation measurements with pyrgeometer arrays were conducted under forests with different densities to evaluate the relationship between effective temperature and forest density. Our preliminary results show that when exposed to direct shortwave radiation, the tree surface temperature shows a significant difference from the air temperature. Under cloudy or shaded conditions, the tree surface temperature closely follows the air temperature. The effective tree temperature follows the air temperature in a dense forest stand, although it is significantly larger than the air temperature near the isolated tree. This discrepancy motivates us to explore ways to represent the effective tree temperature for stands with different densities.

Low temperature self-cleaning properties of superhydrophobic surfaces

NASA Astrophysics Data System (ADS)

Wang, Fajun; Shen, Taohua; Li, Changquan; Li, Wen; Yan, Guilong

2014-10-01

Outdoor surfaces are usually dirty surfaces. Ice accretion on outdoor surfaces could lead to serious accidents. In the present work, the superhydrophobic surface based on 1H, 1H, 2H, 2H-Perfluorodecanethiol (PFDT) modified Ag/PDMS composite was prepared to investigate the anti-icing property and self-cleaning property at temperatures below freezing point. The superhydrophobic surface was deliberately polluted with activated carbon before testing. It was observed that water droplet picked up dusts on the cold superhydrophobic surface and took it away without freezing at a measuring temperature of -10 °C. While on a smooth PFDT surface and a rough surface base on Ag/PDMS composite without PFDT modification, water droplets accumulated and then froze quickly at the same temperature. However, at even lower temperature of -12 °C, the superhydrophobic surface could not prevent the surface water from icing. In addition, it was observed that the frost layer condensed from the moisture pay an important role in determining the low temperature self-cleaning properties of a superhydrophobic surface.

Probing the Active Surface Sites for CO Reduction on Oxide-Derived Copper Electrocatalysts

DOE PAGES

Verdaguer-Casadevall, Arnau; Li, Christina W.; Johansson, Tobias P.; ...

2015-07-30

CO electroreduction activity on oxide-derived Cu (OD-Cu) was found to correlate with metastable surface features that bind CO strongly. OD-Cu electrodes prepared by H 2 reduction of Cu 2O precursors reduce CO to acetate and ethanol with nearly 50% Faradaic efficiency at moderate overpotential. Temperature-programmed desorption of CO on OD-Cu revealed the presence of surface sites with strong CO binding that are distinct from the terraces and stepped sites found on polycrystalline Cu foil. After annealing at 350 °C, the surface-area corrected current density for CO reduction is 44-fold lower and the Faradaic efficiency is less than 5%. These changesmore » are accompanied by a reduction in the proportion of strong CO binding sites. Here, we propose that the active sites for CO reduction on OD-Cu surfaces are strong CO binding sites that are supported by grain boundaries. Uncovering these sites is a first step toward understanding the surface chemistry necessary for efficient CO electroreduction.« less

Development of Nano-Sulfide Sorbent for Efficient Removal of Elemental Mercury from Coal Combustion Fuel Gas.

PubMed

Li, Hailong; Zhu, Lei; Wang, Jun; Li, Liqing; Shih, Kaimin

2016-09-06

The surface area of zinc sulfide (ZnS) was successfully enlarged using nanostructure particles synthesized by a liquid-phase precipitation method. The ZnS with the highest surface area (named Nano-ZnS) of 196.1 m(2)·g(-1) was then used to remove gas-phase elemental mercury (Hg(0)) from simulated coal combustion fuel gas at relatively high temperatures (140 to 260 °C). The Nano-ZnS exhibited far greater Hg(0) adsorption capacity than the conventional bulk ZnS sorbent due to the abundance of surface sulfur sites, which have a high binding affinity for Hg(0). Hg(0) was first physically adsorbed on the sorbent surface and then reacted with the adjacent surface sulfur to form the most stable mercury compound, HgS, which was confirmed by X-ray photoelectron spectroscopy analysis and a temperature-programmed desorption test. At the optimal temperature of 180 °C, the equilibrium Hg(0) adsorption capacity of the Nano-ZnS (inlet Hg(0) concentration of 65.0 μg·m(-3)) was greater than 497.84 μg·g(-1). Compared with several commercial activated carbons used exclusively for gas-phase mercury removal, the Nano-ZnS was superior in both Hg(0) adsorption capacity and adsorption rate. With this excellent Hg(0) removal performance, noncarbon Nano-ZnS may prove to be an advantageous alternative to activated carbon for Hg(0) removal in power plants equipped with particulate matter control devices, while also offering a means of reusing fly ash as a valuable resource, for example as a concrete additive.

Identifying the Thermal Decomposition Mechanism of Guaiacol on Pt(111): An Integrated X-ray Photoelectron Spectroscopy and Density Functional Theory Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hensley, Alyssa J.; Wockel, Claudia; Gleichweit, Christoph

Using a concerted effort from both experiment and theory, we determine the thermal decomposition mechanism for guaiacol on Pt(111), a reaction of interest in the area of bio-oil upgrading. This work serves as a demonstration of the power of combining in situ temperature-programmed X-ray photoelectron spectroscopy cos (TPXPS) and density functional theory (DFT) to elucidate complex reaction mechanisms occurring on heterogeneous surfaces. At low temperature (230 K), guaiacol was found to chemisorb with the aromatic ring parallel to the Pt(111) surface with five distinct carbon species and three oxygen species. As the temperature was increased, TPXPS showed several significant changesmore » to the surface species. The increase in the species associated with the decomposition of the functional groups of guaiacol is followed by their subsequent disappearance and an increase in the nonaromatic carbon signal. On the basis of an energetic analysis of the various mechanisms using DFT, along with the comparison of the experimentally and theoretically derived core-level binding energies, we determined that guaiacol's decomposition mechanism occurs via the dehydrogenation of both the methyl and hydroxyl functional groups, followed by demethylation of the CH2 or CH group to form 1,2-benzoquinone. Further heating to above 375 K likely breaks the aromatic ring and results in the rapid formation and desorption of CO, accounting for the disappearance of the 0 is signal above 450 K These results show that a knowledgeable application of TPXPS and DFT can result in the quantitative identification of surface species during complex reactions, providing insight useful for the design of future heterogeneous surfaces.« less

Adsorption and Photodesorption of CO from Charged Point Defects on TiO 2 (110)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mu, Rentao; Dahal, Arjun; Wang, Zhi-Tao

Adsorption and photodesorption of weakly-bound carbon monoxide, CO, from reduced and hydroxylated rutile TiO2(110) (r- and h- TiO2(110)) at sub-monolayer coverages is studied with atomically-resolved scanning tunneling microscopy (STM) along with ensemble-averaged temperature-programmed desorption (TPD) and angle-resolved photon-stimulated desorption (PSD) at low temperatures ( 50 K). STM data weighted by the concentration of each kind of adsorption sites on r-TiO2(110) give an adsorption probability which is the highest for the bridging oxygen vacancies (VO) and very low for the Ti5c sites closest to VO. Occupancy of the remaining Ti5c sites with CO is significant, but smaller than for VO. Themore » probability distribution for the different adsorption sites corresponds to a very small difference in CO adsorption energies: < 0.02 eV. We also find that UV irradiation stimulates both diffusion and desorption of CO at low temperature. CO photodesorbs primarily from the vacancies with a bi-modal angular distribution. In addition to a major, normal to the surface component, there is a broader cosine component indicating scattering from the surface which likely also leads to photo-stimulated diffusion. Hydroxylation of VO’s does not significantly change the CO PSD yield and angular distribution, indicating that not atomic but rather electronic surface defects are involved in the site-specific PSD process. We suggest that photodesorption can be initiated by recombination of photo-generated holes with excess unpaired electrons localized near the surface point-defect (either VO or bridging hydroxyl), leading to the surface atoms rearrangement and ejection of the weakly-bound CO molecules.« less

Fission Surface Power Systems (FSPS) Project Final Report for the Exploration Technology Development Program (ETDP): Fission Surface Power, Transition Face to Face

NASA Technical Reports Server (NTRS)

Palac, Donald T.

2011-01-01

The Fission Surface Power Systems Project became part of the ETDP on October 1, 2008. Its goal was to demonstrate fission power system technology readiness in an operationally relevant environment, while providing data on fission system characteristics pertinent to the use of a fission power system on planetary surfaces. During fiscal years 08 to 10, the FSPS project activities were dominated by hardware demonstrations of component technologies, to verify their readiness for inclusion in the fission surface power system. These Pathfinders demonstrated multi-kWe Stirling power conversion operating with heat delivered via liquid metal NaK, composite Ti/H2O heat pipe radiator panel operations at 400 K input water temperature, no-moving-part electromagnetic liquid metal pump operation with NaK at flight-like temperatures, and subscale performance of an electric resistance reactor simulator capable of reproducing characteristics of a nuclear reactor for the purpose of system-level testing, and a longer list of component technologies included in the attached report. Based on the successful conclusion of Pathfinder testing, work began in 2010 on design and development of the Technology Demonstration Unit (TDU), a full-scale 1/4 power system-level non-nuclear assembly of a reactor simulator, power conversion, heat rejection, instrumentation and controls, and power management and distribution. The TDU will be developed and fabricated during fiscal years 11 and 12, culminating in initial testing with water cooling replacing the heat rejection system in 2012, and complete testing of the full TDU by the end of 2014. Due to its importance for Mars exploration, potential applicability to missions preceding Mars missions, and readiness for an early system-level demonstration, the Enabling Technology Development and Demonstration program is currently planning to continue the project as the Fission Power Systems project, including emphasis on the TDU completion and testing.

Improved Method Being Developed for Surface Enhancement of Metallic Materials

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Telesman, Jack; Kantzos, Peter T.

2001-01-01

Surface enhancement methods induce a layer of beneficial residual compressive stress to improve the impact (FOD) resistance and fatigue life of metallic materials. A traditional method of surface enhancement often used is shot peening, in which small steel spheres are repeatedly impinged on metallic surfaces. Shot peening is inexpensive and widely used, but the plastic deformation of 20 to 40 percent imparted by the impacts can be harmful. This plastic deformation can damage the microstructure, severely limiting the ductility and durability of the material near the surface. It has also been shown to promote accelerated relaxation of the beneficial compressive residual stresses at elevated temperatures. Low-plasticity burnishing (LPB) is being developed as an improved method for the surface enhancement of metallic materials. LPB is being investigated as a rapid, inexpensive surface enhancement method under NASA Small Business Innovation Research contracts NAS3-98034 and NAS3-99116, with supporting characterization work at NASA. Previously, roller burnishing had been employed to refine surface finish. This concept was adopted and then optimized as a means of producing a layer of compressive stress of high magnitude and depth, with minimal plastic deformation (ref. 1). A simplified diagram of the developed process is given in the following figure. A single pass of a smooth, free-rolling spherical ball under a normal force deforms the surface of the material in tension, creating a compressive layer of residual stress. The ball is supported in a fluid with sufficient pressure to lift the ball off the surface of the retaining spherical socket. The ball is only in mechanical contact with the surface of the material being burnished and is free to roll on the surface. This apparatus is designed to be mounted in the conventional lathes and vertical mills currently used to machine parts. The process has been successfully applied to nickel-base superalloys by a team from the NASA Glenn Research Center, Lambda Research, and METCUT Research, as supported by the NASA Small Business Innovation Research Phase I and II programs, the Ultra Safe program, and the Ultra- Efficient Engine Technology (UEET) Program.

Preparation and High-temperature Anti-adhesion Behavior of a Slippery Surface on Stainless Steel.

PubMed

Zhang, Pengfei; Huawei, Chen; Liu, Guang; Zhang, Liwen; Zhang, Deyuan

2018-03-29

Anti-adhesion surfaces with high-temperature resistance have a wide application potential in electrosurgical instruments, engines, and pipelines. A typical anti-wetting superhydrophobic surface easily fails when exposed to a high-temperature liquid. Recently, Nepenthes-inspired slippery surfaces demonstrated a new way to solve the adhesion problem. A lubricant layer on the slippery surface can act as a barrier between the repelled materials and the surface structure. However, the slippery surfaces in previous studies rarely showed high-temperature resistance. Here, we describe a protocol for the preparation of slippery surfaces with high-temperature resistance. A photolithography-assisted method was used to fabricate pillar structures on stainless steel. By functionalizing the surface with saline, a slippery surface was prepared by adding silicone oil. The prepared slippery surface maintained the anti-wetting property for water, even when the surface was heated to 300 °C. Also, the slippery surface exhibited great anti-adhesion effects on soft tissues at high temperatures. This type of slippery surface on stainless steel has applications in medical devices, mechanical equipment, etc.

Permian paleoclimate data from fluid inclusions in halite

USGS Publications Warehouse

Benison, K.C.; Goldstein, R.H.

1999-01-01

This study has yielded surface water paleotemperatures from primary fluid inclusions in mid Permian Nippewalla Group halite from western Kansas. A 'cooling nucleation' method is used to generate vapor bubbles in originally all-liquid primary inclusions. Then, surface water paleotemperatures are obtained by measuring temperatures of homogenization to liquid. Homogenization temperatures ranged from 21??C to 50??C and are consistent along individual fluid inclusion assemblages, indicating that the fluid inclusions have not been altered by thermal reequilibration. Homogenization temperatures show a range of up to 26??C from base to top of individual cloudy chevron growth bands. Petrographic and fluid inclusion evidence indicate that no significant pressure correction is needed for the homogenization temperature data. We interpret these homogenization temperatures to represent shallow surface water paleotemperatures. The range in temperatures from base to top of single chevron bands may reflect daily temperatures variations. These Permian surface water temperatures fall within the same range as some modern evaporative surface waters, suggesting that this Permian environment may have been relatively similar to its modern counterparts. Shallow surface water temperatures in evaporative settings correspond closely to local air temperatures. Therefore, the Permian surface water temperatures determined in this study may be considered proxies for local Permian air temperatures.

High-Temperature Solid Lubricants Developed by NASA Lewis Offer Virtually "Unlimited Life" for Oil-Free Turbomachinery

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher; Valco, Mark J.

1999-01-01

The NASA Lewis Research Center is capitalizing on breakthroughs in foil air bearing performance, tribological coatings, and computer analyses to formulate the Oil-free Turbomachinery Program. The program s long-term goal is to develop an innovative, yet practical, oil-free aeropropulsion gas turbine engine that floats on advanced air bearings. This type of engine would operate at higher speeds and temperatures with lower weight and friction than conventional oil-lubricated engines. During startup and shutdown, solid lubricant coatings are required to prevent wear in such engines before the self-generating air-lubrication film develops. NASA s Tribology Branch has created PS304, a chrome-oxide-based plasma spray coating specifically tailored for shafts run against foil bearings. PS304 contains silver and barium fluoride/calcium fluoride eutectic (BaF2/CaF2) lubricant additives that, together, provide lubrication from cold start temperatures to over 650 C, the maximum use temperature for foil bearings. Recent lab tests show that bearings lubricated with PS304 survive over 100 000 start-stop cycles without experiencing any degradation in performance due to wear. The accompanying photograph shows a test bearing after it was run at 650 C. The rubbing process created a "polished" surface that enhances bearing load capacity.

Temperature-dependent surface density of alkylthiol monolayers on gold nanocrystals

NASA Astrophysics Data System (ADS)

Liu, Xuepeng; Lu, Pin; Zhai, Hua; Wu, Yucheng

2018-03-01

Atomistic molecular dynamics (MD) simulations are performed to study the surface density of passivating monolayers of alkylthiol chains on gold nanocrystals at temperatures ranging from 1 to 800 K. The results show that the surface density of alkylthiol monolayer reaches a maximum value at near room temperature (200-300 K), while significantly decreases with increasing temperature in the higher temperature region (> 300 {{K}}), and slightly decreases with decreasing temperature at low temperature (< 200 {{K}}). We find that the temperature dependence of surface ligand density in the higher temperature region is attributed to the substantial ligand desorption induced by the thermal fluctuation, while that at low temperature results from the reduction in entropy caused by the change in the ordering of passivating monolayer. These results are expected helpful to understand the temperature-dependent surface coverage of gold nanocrystals.

Ultrathin Bi2WO6 nanosheet decorated with Pt nanoparticles for efficient formaldehyde removal at room temperature

NASA Astrophysics Data System (ADS)

Sun, Dong; Le, Yao; Jiang, Chuanjia; Cheng, Bei

2018-05-01

Two-dimensional (2D) ultrathin bismuth tungstate (Bi2WO6) nanosheets (BWO-NS) with a thickness of approximately 4.0 nm were synthesized by a one-step hydrothermal method, and decorated with platinum (Pt) nanoparticles (NPs) via an impregnation/borohydride-reduction approach. The as-prepared ultrathin Pt-BWO-NS exhibited superior catalytic activity for removing gaseous formaldehyde (HCHO) at ambient temperature, in comparison with bulk counterpart with Bi2WO6 sheet thickness of tens of nanometers. The ultrathin structure endowed the Pt-BWO-NS sample with larger specific surface area, which can provide abundant surface active sites for HCHO adsorption and facilitate the homogeneous dispersion of Pt NPs. X-ray photoelectron spectroscopy and hydrogen temperature-programmed reduction analyses revealed the interaction between the Bi2WO6 support and Pt species, which is crucial for activating surface oxygen atoms to participate in the catalytic HCHO oxidation process. By conducting in situ diffuse reflectance infrared Fourier transform spectroscopy under different atmospheres, i.e., gaseous HCHO in nitrogen or oxygen (O2), the reaction mechanism and the role of O2 were elucidated, with dioxymethylene, formate and linearly adsorbed carbon monoxide identified as the main reaction intermediates. This study may provide new enlightenment on fabricating novel 2D nanomaterials for efficient indoor air purification and potentially other environmental applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sather, Nichole K.; Borde, Amy B.; Diefenderfer, Heida L.

This Handbook of Data Reduction Procedures, Workbooks, and Exchange Templates is designed to support the Oncor geodatabase for the Columbia Estuary Ecosystem Restoration Program (CEERP). The following data categories are covered: water-surface elevation and temperature, sediment accretion rate, photo points, herbaceous wetland vegetation cover, tree plots and site summaries, fish catch and density, fish size, fish diet, fish prey, and Chinook salmon genetic stock identification. The handbook is intended for use by scientists collecting monitoring and research data for the CEERP. The ultimate goal of Oncor is to provide quality, easily accessible, geospatial data for synthesis and evaluation of themore » collective performance of CEERP ecosystem restoration actions at a program scale.« less

Estimation of subsurface thermal structure using sea surface height and sea surface temperature

NASA Technical Reports Server (NTRS)

Kang, Yong Q. (Inventor); Jo, Young-Heon (Inventor); Yan, Xiao-Hai (Inventor)

2012-01-01

A method of determining a subsurface temperature in a body of water is disclosed. The method includes obtaining surface temperature anomaly data and surface height anomaly data of the body of water for a region of interest, and also obtaining subsurface temperature anomaly data for the region of interest at a plurality of depths. The method further includes regressing the obtained surface temperature anomaly data and surface height anomaly data for the region of interest with the obtained subsurface temperature anomaly data for the plurality of depths to generate regression coefficients, estimating a subsurface temperature at one or more other depths for the region of interest based on the generated regression coefficients and outputting the estimated subsurface temperature at the one or more other depths. Using the estimated subsurface temperature, signal propagation times and trajectories of marine life in the body of water are determined.

Diffusion bonding

DOEpatents

Anderson, Robert C.

1976-06-22

1. A method for joining beryllium to beryllium by diffusion bonding, comprising the steps of coating at least one surface portion of at least two beryllium pieces with nickel, positioning a coated surface portion in a contiguous relationship with an other surface portion, subjecting the contiguously disposed surface portions to an environment having an atmosphere at a pressure lower than ambient pressure, applying a force upon the beryllium pieces for causing the contiguous surface portions to abut against each other, heating the contiguous surface portions to a maximum temperature less than the melting temperature of the beryllium, substantially uniformly decreasing the applied force while increasing the temperature after attaining a temperature substantially above room temperature, and maintaining a portion of the applied force at a temperature corresponding to about maximum temperature for a duration sufficient to effect the diffusion bond between the contiguous surface portions.

Dynamic, Hot Surface Ignition of Aircraft Fuels and Hydraulic Fluids

DTIC Science & Technology

1980-10-01

fuels on a heated stainless steel surface. Higher local surface air speeds necessitated higher surface temperatures for ignition of an applied fluid._-7...Aircraft Fuels ( stainless steel surface) 8. Air Speed and Surface Material Effects on Hot Surface 21 Ignition Temperature of Aircraft Fuels (Titanium...Material Effects on Hot Surface 26 Ignition Temperature of Aircraft Hydraulic Fluids ( Stainless steel surface) 11. Air Speed and Surface Material

ITEL Experiment Module and its Flight on MASER9

NASA Astrophysics Data System (ADS)

Löth, K.; Schneider, H.; Larsson, B.; Jansson, O.; Houltz, Y.

2002-01-01

The ITEL (Interfacial Turbulence in Evaporating Liquid) module is built under contract from the European Space Agency (ESA) and is scheduled to fly onboard a Sounding Rocket (MASER 9) in March 2002. The project is conducted by Swedish Space Corporation (SSC) with Lambda-X as a subcontractor responsible for the optical system. The Principle Investigator is Pierre Colinet from Université Libre de Bruxelles (ULB). The experiment in ITEL on Maser 9 is part of a research program, which will make use of the International Space Station. The purpose of the flight on Maser 9 is to observe the cellular convection (Marangoni-Bénard instability) which arise when the surface tension varies with temperature yielding thermocapillary instabilities. During the 6 minutes of microgravity of the ITEL experiment, a highly volatile liquid layer (ethyl alcohol) will be evaporated, and the convection phenomena generated by the evaporation process will be visualized. Due to the cooling by latent heat consumption at the level of the evaporating free surface, a temperature gradient is induced perpendicularly to it. The flight experiment module contains one experiment cell, including a gas system for regulation of nitrogen flow over the evaporating surface and an injection unit that is used for injection of liquid into the cell both initially and during surface regulation. The experiment cell is equipped with pressure and flow sensors as well as thermocouples both inside the liquid and at different positions in the cell. Two optical diagnostic systems have been developed around the experiment cell. An interferometric optical tomograph measures the 3-dimensional distribution of temperature in the evaporating liquid and a Schlieren system visualizes the temperature gradients inside the liquid together with the liquid surface deformation. A PC/104 based electronic system is used for management and control of the experiment. The electronic system handles measurements, housekeeping, image capture system, surface and pressure regulation as well as storage of data. The images are stored onboard on three DV tape recorders. At flight, video images as well as data is sent to ground and the experiment can be controlled via telecommands. In this presentation we will focus on the technical parts of the experiment, the overall module and the preliminary technical results obtained from the flight, including reconstructions of 3-dimensional temperature distributions.

Promising SiC support for Pd catalyst in selective hydrogenation of acetylene to ethylene

NASA Astrophysics Data System (ADS)

Guo, Zhanglong; Liu, Yuefeng; Liu, Yan; Chu, Wei

2018-06-01

In this study, SiC supported Pd nanoparticles were found to be an efficient catalyst in acetylene selective hydrogenation reaction. The ethylene selectivity can be about 20% higher than that on Pd/TiO2 catalyst at the same acetylene conversion at 90%. Moreover, Pd/SiC catalyst showed a stable catalytic life at 65 °C with 80% ethylene selectivity. With the detailed characterization using temperature-programmed reduction (H2-TPR), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption/desorption analysis, CO-chemisorption and thermo-gravimetric analysis (TGA), it was found that SiC owns a lower surface area (22.9 m2/g) and a broad distribution of meso-/macro-porosity (from 5 to 65 nm), which enhanced the mass transfer during the chemical process at high reaction rate and decreased the residence time of ethylene on catalyst surface. Importantly, SiC support has the high thermal conductivity, which favored the rapid temperature homogenization through the catalyst bed and inhabited the over-hydrogenation of acetylene. The surface electronic density of Pd on Pd/SiC catalyst was higher than that on Pd/TiO2, which could promote desorption of ethylene from surface of the catalyst. TGA results confirmed a much less coke deposition on Pd/SiC catalyst.

Automated 3D Damaged Cavity Model Builder for Lower Surface Acreage Tile on Orbiter

NASA Technical Reports Server (NTRS)

Belknap, Shannon; Zhang, Michael

2013-01-01

The 3D Automated Thermal Tool for Damaged Acreage Tile Math Model builder was developed to perform quickly and accurately 3D thermal analyses on damaged lower surface acreage tiles and structures beneath the damaged locations on a Space Shuttle Orbiter. The 3D model builder created both TRASYS geometric math models (GMMs) and SINDA thermal math models (TMMs) to simulate an idealized damaged cavity in the damaged tile(s). The GMMs are processed in TRASYS to generate radiation conductors between the surfaces in the cavity. The radiation conductors are inserted into the TMMs, which are processed in SINDA to generate temperature histories for all of the nodes on each layer of the TMM. The invention allows a thermal analyst to create quickly and accurately a 3D model of a damaged lower surface tile on the orbiter. The 3D model builder can generate a GMM and the correspond ing TMM in one or two minutes, with the damaged cavity included in the tile material. A separate program creates a configuration file, which would take a couple of minutes to edit. This configuration file is read by the model builder program to determine the location of the damage, the correct tile type, tile thickness, structure thickness, and SIP thickness of the damage, so that the model builder program can build an accurate model at the specified location. Once the models are built, they are processed by the TRASYS and SINDA.

Near Surface Thermal Stratification during Summer at Summit, Greenland, and its Impact on MODIS-derived Surface Temperatures

NASA Astrophysics Data System (ADS)

Adolph, A. C.; Albert, M. R.; Hall, D. K.

2017-12-01

As rapid warming of the Arctic occurs, it is imperative that we monitor climate parameters such as temperature over large areas to understand and predict the extent of climate changes. Temperatures are often tracked using in-situ 2 m air temperatures, but in remote locations such as on the Greenland Ice Sheet, temperature can be studied more comprehensively using remote sensing techniques. Because of the presence of surface-based temperature inversions in ice-covered areas, differences between 2 m air temperature and skin temperature can be significant and are particularly relevant when considering validation and application of remote sensing temperature data. We present results from a field campaign at Summit Station in Greenland to study surface temperature using the following measurements: skin temperature measured by IR sensors, thermochrons, and thermocouples; 2 m air temperature measured by a NOAA meteorological station; and two different MODerate-resolution Imaging Spectroradiometer (MODIS) surface temperature products. We confirm prior findings that in-situ 2 m air temperature is often significantly higher in the summer than in-situ skin temperature when incoming solar radiation and wind speed are low. This inversion may account for biases in previous MODIS surface temperature studies that used 2 m air temperature for validation. As compared to the in-situ IR skin temperature measurements, the MOD/MYD11 Collection 6 surface-temperature standard product has an RMSE of 1.0°C, and that the MOD29 Collection 6 product has an RMSE of 1.5°C, spanning a range of temperatures from -35°C to -5°C. For our study area and time series, MODIS surface temperature products agree with skin temperatures better than many previous studies have indicated, especially at temperatures below -20°C where other studies found a significant cold bias. Further investigation at temperatures below -35°C is warranted to determine if this bias does indeed exist.

High-frequency fluctuations of surface temperatures in an urban environment

NASA Astrophysics Data System (ADS)

Christen, Andreas; Meier, Fred; Scherer, Dieter

2012-04-01

This study presents an attempt to resolve fluctuations in surface temperatures at scales of a few seconds to several minutes using time-sequential thermography (TST) from a ground-based platform. A scheme is presented to decompose a TST dataset into fluctuating, high-frequency, and long-term mean parts. To demonstrate the scheme's application, a set of four TST runs (day/night, leaves-on/leaves-off) recorded from a 125-m-high platform above a complex urban environment in Berlin, Germany is used. Fluctuations in surface temperatures of different urban facets are measured and related to surface properties (material and form) and possible error sources. A number of relationships were found: (1) Surfaces with surface temperatures that were significantly different from air temperature experienced the highest fluctuations. (2) With increasing surface temperature above (below) air temperature, surface temperature fluctuations experienced a stronger negative (positive) skewness. (3) Surface materials with lower thermal admittance (lawns, leaves) showed higher fluctuations than surfaces with high thermal admittance (walls, roads). (4) Surface temperatures of emerged leaves fluctuate more compared to trees in a leaves-off situation. (5) In many cases, observed fluctuations were coherent across several neighboring pixels. The evidence from (1) to (5) suggests that atmospheric turbulence is a significant contributor to fluctuations. The study underlines the potential of using high-frequency thermal remote sensing in energy balance and turbulence studies at complex land-atmosphere interfaces.

Comparing AIRS/AMSU-A Satellite and MERRA/MERRA-2 Reanalysis products with In-situ Station Observations at Summit, Greenland

NASA Astrophysics Data System (ADS)

Hearty, T. J., III; Vollmer, B.; Wei, J. C.; Huwe, P. M.; Albayrak, A.; Wu, D. L.; Cullather, R. I.; Meyer, D. L.; Lee, J. N.; Blaisdell, J. M.; Susskind, J.; Nowicki, S.

2017-12-01

The surface air and skin temperatures reported by the Atmospheric Infrared Sounder (AIRS), the Modern-Era Retrospective analysis for Research and Applications (MERRA), and MERRA-2 at Summit, Greenland are compared with near surface air temperatures measured at National Oceanic and Atmospheric Administration (NOAA) and Greenland Climate Network (GC-Net) weather stations. Therefore this investigation requires familiarity with a heterogeneous set of swath, grid, and point data in several different formats, different granularity, and different sampling. We discuss the current subsetting capabilities available at the GES DISC (Goddard Earth Sciences Data Information Services Center) to perform the inter-comparisons necessary to evaluate the quality and trustworthiness of these datasets. We also explore potential future services which may assist users with this type of intercomparison. We find the AIRS Surface Skin Temperature (TS) is best correlated with the NOAA 2 m air temperature (T2M) but it tends to be colder than the station measurements. The difference may be the result of the frequent near surface temperature inversions in the region. The AIRS Surface Air Temperature (SAT) is also well correlated with the NOAA T2M but it has a warm bias with respect to the NOAA T2M during the cold season and a larger standard error than surface temperature. This suggests that the extrapolation of the temperature profile to the surface is not valid for the strongest inversions. Comparing the temperature lapse rate derived from the 2 stations shows that the lapse rate can increase closer to the surface. We also find that the difference between the AIRS SAT and TS is sensitive to near surface inversions. The MERRA-2 surface and near surface temperatures show improvements over MERRA but little sensitivity to near surface temperature inversions.

CO Diffusion and Desorption Kinetics in CO2 Ices

NASA Astrophysics Data System (ADS)

Cooke, Ilsa R.; Öberg, Karin I.; Fayolle, Edith C.; Peeler, Zoe; Bergner, Jennifer B.

2018-01-01

The diffusion of species in icy dust grain mantles is a fundamental process that shapes the chemistry of interstellar regions; yet, measurements of diffusion in interstellar ice analogs are scarce. Here we present measurements of CO diffusion into CO2 ice at low temperatures (T = 11–23 K) using CO2 longitudinal optical phonon modes to monitor the level of mixing of initially layered ices. We model the diffusion kinetics using Fick’s second law and find that the temperature-dependent diffusion coefficients are well fit by an Arrhenius equation, giving a diffusion barrier of 300 ± 40 K. The low barrier along with the diffusion kinetics through isotopically labeled layers suggest that CO diffuses through CO2 along pore surfaces rather than through bulk diffusion. In complementary experiments, we measure the desorption energy of CO from CO2 ices deposited at 11–50 K by temperature programmed desorption and find that the desorption barrier ranges from 1240 ± 90 K to 1410 ± 70 K depending on the CO2 deposition temperature and resultant ice porosity. The measured CO–CO2 desorption barriers demonstrate that CO binds equally well to CO2 and H2O ices when both are compact. The CO–CO2 diffusion–desorption barrier ratio ranges from 0.21 to 0.24 dependent on the binding environment during diffusion. The diffusion–desorption ratio is consistent with the above hypothesis that the observed diffusion is a surface process and adds to previous experimental evidence on diffusion in water ice that suggests surface diffusion is important to the mobility of molecules within interstellar ices.

Heating Pad Performance and Efficacy of 2 Durations of Warming after Isoflurane Anesthesia of Sprague-Dawley Rats (Rattus norvegicus).

PubMed

Zhang, Emily Q; Knight, Cameron G; Pang, Daniel Sj

2017-11-01

Anesthetic agents depress thermoregulatory mechanisms, causing hypothermia within minutes of induction of general anesthesia. The consequences of hypothermia include delayed recovery and increased experimental variability. Even when normothermia is maintained during anesthesia, hypothermia may occur during recovery. The primary aim of this study was to identify an effective warming period for maintaining normothermia during recovery. Adult male (n = 8) and female (n = 9) Sprague-Dawley rats were randomized to 30 min (post30) or 60 min (post60) of warming after recovery from anesthesia. During a 40-min anesthetic period, normothermia (target, 37.5 ± 1.1 °C) was maintained by manual adjustment of an electric heating pad in response to measured rectal temperatures (corrected to estimate core body temperature). Warming was continued in a recovery cage according to treatment group. Rectal temperature was measured for a total of 120 min after anesthesia. Heating pad performance was assessed by measuring temperatures at various sites over its surface. One female rat in the post30 group was excluded from analysis. Normothermia was effectively maintained during and after anesthesia without significant differences between groups. In the post60 group, core temperature was slightly but significantly increased at 90 and 100 min compared with baseline. One rat in each treatment group became hyperthermic (>38.6 °C) during recovery. During recovery, the cage floor temperature required approximately 30 min to stabilize. The heating pad produced heat unevenly over its surface, and measured temperatures frequently exceeded the programmed temperature. Providing 30 min of warming immediately after anesthesia effectively prevented hypothermia in rats. Shorter warming periods may be useful when recovery cages are preheated.

Thermophysical Property Measurements of Molten Semiconductors in 1-g and Reduced-g Condition

NASA Technical Reports Server (NTRS)

Rhim, Won-Kyu

1999-01-01

Understanding and controlling the formation kinetics of varieties of crystal imperfections such as point defects, non uniform distribution of doping atoms, and impurity atoms in growing crystals are very important. Theoretical (numerical) modeling of the crystal growth process is an essential step to achieving these objectives. In order to obtain reliable modeling results, input parameters, i.e. various thermophysical parameters, must be accurate. The importance of accurate thermophysical properties of semiconductors in crystal growth cannot be overly emphasized. The total hemispherical emissivity, for instance, has a dramatic impact on the thermal environment. It determines the radiative emission from the surface of the melt which determines to a large extent the profile of the solidified crystal. In order to understand the convection and the turbulence in a melt, viscosity becomes an important parameter. The liquid surface tension determines the shape of the liquid-atmosphere interface near the solid-liquid-atmosphere triple point. Currently used values for these parameters are rather inaccurate, and this program intends to provide more reliable measurements of these thermophysical properties. Thus, the objective of this program is in the accurate measurements of various thermophysical properties which can be reliably used in the modeling of various crystal growth processes. In this program, thermophysical properties of molten semiconductors, such as Si, Ge, Si-Ge, and InSb will be measured as a function of temperature using the High Temperature Electrostatic Levitator at JPL. Each material will be doped by different kinds of impurities at various doping levels. Thermophysical properties which will be measured include: density, thermal expansion coefficient, surface tension, viscosity, specific heat, hemispherical total emissivity, and perhaps electrical and thermal conductivities. Many molten semiconductors are chemically reactive with crucibles. As a result, these dispersed impurities in the melts tend to substantially modify the properties of pure semiconductors. Sample levitation done in a vacuum clearly helps maintain the sample purity. However, in the 1-g environment, all gravity caused effects such as convection, sedimentation and buoyancy are still present in the sample. In addition, large forces needed to levitate a sample in the presence of the gravity can cause additional flows in the melt. The use of the High Temperature Electrostatic Levitator (HTESL) for the present research is a recent development and little is known about the flows induced by the electrostatic forces. In this ground base program, we will define the limits of HTESL technology as various thermophysical properties of molten semiconductors are measured.

Nonlinear dynamic model of a gear-rotor-bearing system considering the flash temperature

NASA Astrophysics Data System (ADS)

Gou, Xiangfeng; Zhu, Lingyun; Qi, Changjun

2017-12-01

The instantaneous flash temperature is an important factor for gears in service. To investigate the effect of the flash temperature of a tooth surface on the dynamics of the spur gear system, a modified nonlinear dynamic model of a gear-rotor-bearing system is established. The factors such as the contact temperature of the tooth surface, time-varying stiffness, tooth surface friction, backlash, the comprehensive transmission error and so on are considered. The flash temperature of a tooth surface of pinion and gear is formulated according to Blok's flash temperature theory. The mathematical expression of the contact temperature of the tooth surface varied with time is derived and the tooth profile deformation caused by the change of the flash temperature of the tooth surface is calculated. The expression of the mesh stiffness varied with the flash temperature of the tooth surface is derived based on Hertz contact theory. The temperature stiffness is proposed and added to the nonlinear dynamic model of the system. The influence of load on the flash temperature of the tooth surface is analyzed in the parameters plane. The variation of the flash temperature of the tooth surface is studied. The numerical results indicate that the calculated method of the flash temperature of the gear tooth surface is effective and it can reflect the rules for the change of gear meshing temperature and sliding of the gear tooth surface. The effects of frequency, backlash, bearing clearance, comprehensive transmission error and time-varying stiffness on the nonlinear dynamics of the system are analyzed according to the bifurcation diagrams, Top Lyapunov Exponent (TLE) spectrums, phase portraits and Poincaré maps. Some nonlinear phenomena such as periodic bifurcation, grazing bifurcation, quasi-periodic bifurcation, chaos and its routes to chaos are investigated and the critical parameters are identified. The results provide an understanding of the system and serve as a useful reference in designing such systems.

Mesoporous Carbons With Self-Assembled High-Activity Surfaces (PREPRINT)

DTIC Science & Technology

2006-07-07

temperature-programmed desorption, and potentiometric titrations . Journal of Colloid and Interface Science 2001; 240: 252–258. [40] Rotkin SV, Gogotsi Y...selected carbon samples were treated with nitric acid and the total acid site density determined by base titration [32-34 Boehm 1994; Boehm 2002; 32...washed thoroughly using distilled/deionized water, and dried in the oven. For the titration , 50 mg of HNO3-treated carbon powder was added to 20 ml

Improving estimates of forest disturbance by combining observations from Landsat time series with U.S. Forest Service Forest Inventory and Analysis data

Treesearch

Todd A. Schroeder; Sean P. Healey; Gretchen G. Moisen; Tracey S. Frescino; Warren B. Cohen; Chengquan Huang; Robert E. Kennedy; Zhiqiang Yang

2014-01-01

With earth's surface temperature and human population both on the rise a new emphasis has been placed on monitoring changes to forested ecosystems the world over. In the United States the U.S. Forest Service Forest Inventory and Analysis (FIA) program monitors the forested land base with field data collected over a permanent network of sample plots. Although these...

Alumina fiber strength improvement

NASA Technical Reports Server (NTRS)

Pepper, R. T.; Nelson, D. C.

1982-01-01

The effective fiber strength of alumina fibers in an aluminum composite was increased to 173,000 psi. A high temperature heat treatment, combined with a glassy carbon surface coating, was used to prevent degradation and improve fiber tensile strength. Attempts to achieve chemical strengthening of the alumina fiber by chromium oxide and boron oxide coatings proved unsuccessful. A major problem encountered on the program was the low and inconsistent strength of the Dupont Fiber FP used for the investigation.