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Sample records for spaced sublimation technique

  1. Enhanced performance of CdS/CdTe thin-film devices through temperature profiling techniques applied to close-spaced sublimation deposition

    SciTech Connect

    Xiaonan Li; Sheldon, P.; Moutinho, H.; Matson, R.

    1996-05-01

    The authors describe a methodology developed and applied to the close-spaced sublimation technique for thin-film CdTe deposition. The developed temperature profiles consisted of three discrete temperature segments, which the authors called the nucleation, plugging, and annealing temperatures. They have demonstrated that these temperature profiles can be used to grow large-grain material, plug pinholes, and improve CdS/CdTe photovoltaic device performance by about 15%. The improved material and device properties have been obtained while maintaining deposition temperatures compatible with commercially available substrates. This temperature profiling technique can be easily applied to a manufacturing environment by adjusting the temperature as a function of substrate position instead of time.

  2. Optimization of fast dissolving etoricoxib tablets prepared by sublimation technique.

    PubMed

    Patel, D M; Patel, M M

    2008-01-01

    The purpose of this investigation was to develop fast dissolving tablets of etoricoxib. Granules containing etoricoxib, menthol, crospovidone, aspartame and mannitol were prepared by wet granulation technique. Menthol was sublimed from the granules by exposing the granules to vacuum. The porous granules were then compressed in to tablets. Alternatively, tablets were first prepared and later exposed to vacuum. The tablets were evaluated for percentage friability and disintegration time. A 3(2) full factorial design was applied to investigate the combined effect of 2 formulation variables: amount of menthol and crospovidone. The results of multiple regression analysis indicated that for obtaining fast dissolving tablets; optimum amount of menthol and higher percentage of crospovidone should be used. A surface response plots are also presented to graphically represent the effect of the independent variables on the percentage friability and disintegration time. The validity of a generated mathematical model was tested by preparing a checkpoint batch. Sublimation of menthol from tablets resulted in rapid disintegration as compared with the tablets prepared from granules that were exposed to vacuum. The optimized tablet formulation was compared with conventional marketed tablets for percentage drug dissolved in 30 min (Q(30)) and dissolution efficiency after 30 min (DE(30)). From the results, it was concluded that fast dissolving tablets with improved etoricoxib dissolution could be prepared by sublimation of tablets containing suitable subliming agent. PMID:20390084

  3. Optimization of Fast Dissolving Etoricoxib Tablets Prepared by Sublimation Technique

    PubMed Central

    Patel, D. M.; Patel, M. M.

    2008-01-01

    The purpose of this investigation was to develop fast dissolving tablets of etoricoxib. Granules containing etoricoxib, menthol, crospovidone, aspartame and mannitol were prepared by wet granulation technique. Menthol was sublimed from the granules by exposing the granules to vacuum. The porous granules were then compressed in to tablets. Alternatively, tablets were first prepared and later exposed to vacuum. The tablets were evaluated for percentage friability and disintegration time. A 32 full factorial design was applied to investigate the combined effect of 2 formulation variables: amount of menthol and crospovidone. The results of multiple regression analysis indicated that for obtaining fast dissolving tablets; optimum amount of menthol and higher percentage of crospovidone should be used. A surface response plots are also presented to graphically represent the effect of the independent variables on the percentage friability and disintegration time. The validity of a generated mathematical model was tested by preparing a checkpoint batch. Sublimation of menthol from tablets resulted in rapid disintegration as compared with the tablets prepared from granules that were exposed to vacuum. The optimized tablet formulation was compared with conventional marketed tablets for percentage drug dissolved in 30 min (Q30) and dissolution efficiency after 30 min (DE30). From the results, it was concluded that fast dissolving tablets with improved etoricoxib dissolution could be prepared by sublimation of tablets containing suitable subliming agent. PMID:20390084

  4. Possibility of graphene growth by close space sublimation.

    PubMed

    Sopinskyy, Mykola V; Khomchenko, Viktoriya S; Strelchuk, Viktor V; Nikolenko, Andrii S; Olchovyk, Genadiy P; Vishnyak, Volodymyr V; Stonis, Viktor V

    2014-01-01

    Carbon films on the Si/SiO2 substrate are fabricated using modified method of close space sublimation at atmospheric pressure. The film properties have been characterized by micro-Raman and X-ray photoelectron spectroscopy and monochromatic ellipsometry methods. Ellipsometrical measurements demonstrated an increase of the silicon oxide film thickness in the course of manufacturing process. The XPS survey spectra of the as-prepared samples indicate that the main elements in the near-surface region are carbon, silicon, and oxygen. The narrow-scan spectra of C1s, Si2p, O1s regions indicate that silicon and oxygen are mainly in the SiOx (x ≈ 2) oxide form, whereas the main component of C1s spectrum at 284.4 eV comes from the sp2-hybridized carbon phase. Micro-Raman spectra confirmed the formation of graphene films with the number of layers that depended on the distance between the graphite source and substrate. PMID:24731549

  5. Growth of CdTe thin films on graphene by close-spaced sublimation method

    SciTech Connect

    Jung, Younghun; Yang, Gwangseok; Kim, Jihyun; Chun, Seungju; Kim, Donghwan

    2013-12-02

    CdTe thin films grown on bi-layer graphene were demonstrated by using the close-spaced sublimation method, where CdTe was selectively grown on the graphene. The density of the CdTe domains was increased with increasing the number of the defective sites in the graphene, which was controlled by the duration of UV exposure. The CdTe growth rate on the bi-layer graphene electrodes was 400 nm/min with a bandgap energy of 1.45–1.49 eV. Scanning electron microscopy, micro-Raman spectroscopy, micro-photoluminescence, and X-ray diffraction technique were used to confirm the high quality of the CdTe thin films grown on the graphene electrodes.

  6. CdZnS thin films sublimated by closed space using mechanical mixing: A new approach

    NASA Astrophysics Data System (ADS)

    Mahmood, Waqar; Shah, Nazar Abbas

    2014-06-01

    Cadmium sulfide (CdS) is a prominent material for its tunable band gap used as a window layer in II-VI semiconductor solar cells. The light trapping capability of window layer is one of the powerful tools to enhance the efficiency of the cell. CdS and zinc (Zn) powders were mixed mechanically with different weight percents to make CdZnS (CZS) powder. CZS was deposited onto an ultrasonically cleaned glass substrate using close spaced sublimation (CSS) technique. CZS as-deposited thin films were characterized for structural, surface morphology with energy dispersive X-rays (EDX) and optical properties for the use of window layer in CdS/CdTe based solar cells. The different Zn concentrations in CZS played a vital role on crystallite size in structural analysis and optical properties e.g. transmission, absorption coefficient and energy band gap, etc. The crystallite size of as-deposited CZS thin films were increased as Zn concentration was increased up to certain value. The energy band gap varies from 2.42 eV to 2.57 eV for as-deposited CZS thin films with increasing Zn concentrations and surface morphology changes also. These changes were occurred due to zinc diffusion in CdS thin films. An angle resolved transmission data was taken to check the behavior of CdS and CZS thin film at different angles. A comparative study was carried out between CdS thin films and CZS thin films for the use of good window layer material.

  7. Induced Recrystallization of CdTe Thin Films Deposited by Close-Spaced Sublimation

    SciTech Connect

    Moutinho, H. R.; Dhere, R. G.; Al-Jassim, M. M.; Levi, D. H.; Kazmerski, L. L.; Mayo, B.

    1998-10-29

    We have deposited CdTe thin films by close-spaced sublimation at two different temperature ranges. The films deposited at the lower temperature partially recrystallized after CdCl{sub 2} treatment at 350 C and completely recrystallized after the same treatment at 400 C. The films deposited at higher temperature did not recrystallize at these two temperatures. These results confirmed that the mechanisms responsible for changes in physical properties of CdTe films treated with CdCl{sub 2} are recrystallization and grain growth, and provided an alternative method to deposit CSS films using lower temperatures.

  8. Induced Recrystallization of CdTe Thin Films Deposited by Close-Spaced Sublimation

    SciTech Connect

    Moutinho, H. R.; Dhere, R. G.; Al-Jassim, M. M.; Levi, D. H.; Kazmerski, L. L.; Mayo, B.

    1998-10-26

    We have deposited CdTe thin films by close-spaced sublimation at two different temperature ranges. The films deposited at the lower temperature partially recrystallized after CdCl2 treatment at 350 C and completely recrystallized after the same treatment at 400 C. The films deposited at higher temperature did not recrystallize at these two temperatures. These results confirmed that the mechanisms responsible for changes in physical properties of CdTe films treated with CdCl2 are recrystallization and grain growth, and provided an alternative method to deposit CSS films using lower temperatures.

  9. Time-resolved photoluminescence of polycrystalline CdTe grown by close-spaced sublimation

    SciTech Connect

    Keyes, B.; Dhere, R.; Ramanathan, K. )

    1994-06-30

    Polycrystalline CdTe has shown great promise as a low-cost material for thin-film, terrestrial photovoltaic applications, with efficiencies approaching 16% achieved with close-spaced sublimation (CSS)-grown CdTe. Due to the inherent complexities of polycrystalline material, much of the progress in this area has occurred through a slow trial-and-error process. This report uses time-resolved photoluminescence (TRPL) to characterize the CdTe material quality as a function of one basic growth parameter---substrate temperature. This characterization is done for two different glass substrate materials, soda-lime silicate and borosilicate.

  10. Novel Strategy to Fabricate Floating Drug Delivery System Based on Sublimation Technique.

    PubMed

    Huanbutta, Kampanart; Limmatvapirat, Sontaya; Sungthongjeen, Srisagul; Sriamornsak, Pornsak

    2016-06-01

    The present study aims to develop floating drug delivery system by sublimation of ammonium carbonate (AMC). The core tablets contain a model drug, hydrochlorothiazide, and various levels (i.e., 0-50% w/w) of AMC. The tablets were then coated with different amounts of the polyacrylate polymers (i.e., Eudragit® RL100, Eudragit® RS100, and the mixture of Eudragit® RL100 and Eudragit® RS100 at 1:1 ratio). The coated tablets were kept at ambient temperature (25°C) or cured at 70°C for 12 h before further investigation. The floating and drug release behaviors of the tablets were performed in simulated gastric fluid USP without pepsin at 37°C. The results showed that high amount of AMC induced the floating of the tablets. The coated tablets containing 40 and 50% AMC floated longer than 8 h with a time-to-float of about 3 min. The sublimation of AMC from the core tablets decreased the density of system, causing floating of the tablets. The tablets coated with Eudragit® RL100 floated at a faster rate than those of Eudragit® RS100. Even the coating level of polymer did not influence the time-to-float and floating time of coated tablets containing the same amount of AMC, the drug release from the tablets coated with higher coating level of polymer showed slower drug release. The results suggested that the sublimation technique using AMC is promising for the development of floating drug delivery system. PMID:26314245

  11. Induced recrystallization of CdTe thin films deposited by close-spaced sublimation

    SciTech Connect

    Moutinho, H.R.; Dhere, R.G.; Al-Jassim, M.M.; Levi, D.H.; Kazmerski, L.L.; Mayo, B.

    1999-03-01

    We have deposited CdTe thin films by close-spaced sublimation at two different temperature ranges. The films deposited at the lower temperature partially recrystallized after CdCl{sub 2} treatment at 350&hthinsp;{degree}C and completely recrystallized after the same treatment at 400&hthinsp;{degree}C. The films deposited at higher temperature did not recrystallize at these two temperatures. These results confirmed that the mechanisms responsible for changes in physical properties of CdTe films treated with CdCl{sub 2} are recrystallization and grain growth, and provided an alternative method to deposit CSS films using lower temperatures. {copyright} {ital 1999 American Institute of Physics.}

  12. Native Defect Control of CdTe Thin Film Solar Cells by Close-Spaced Sublimation

    NASA Astrophysics Data System (ADS)

    Okamoto, Tamotsu; Kitamoto, Shinji; Yamada, Akira; Konagai, Makoto

    2001-05-01

    The control of native defects in the CdTe thin film solar cells was investigated using a novel source for close-spaced sublimation (CSS) process which was prepared by vacuum evaporation with elemental Cd and Te (evaporated source). The evaporated sources were prepared on glass substrates at room temperature, and the Cd/Te ratio was controlled by varying the Cd and Te beam equivalent pressures. In the cells using the Te-rich source, the conversion efficiency was less than 0.2% because of the extremely low shunt resistance. On the other hand, a conversion efficiency above 15% was obtained by using the Cd-rich source. Capacitance-voltage (C-V) characteristics revealed that the acceptor concentration in the CdTe layer increased with increasing Cd/Te ratio of the evaporated source. Furthermore, photoluminescence spectra implied that the formation of the Cd vacancies in the CdTe layer was suppressed using the Cd-rich source.

  13. Selective Growth of CdTe on Nano-patterned CdS via Close-Space Sublimation

    NASA Astrophysics Data System (ADS)

    Aguirre, Brandon A.; Zubia, David; Ordonez, Rafael; Anwar, Farhana; Prieto, Heber; Sanchez, Carlos A.; Salazar, Maria T.; Pimentel, Alejandro. A.; Michael, Joseph R.; Zhou, Xiaowang; Mcclure, John C.; Nielson, Gregory N.; Cruz-Campa, Jose L.

    2014-07-01

    Selective-area deposition of CdTe on CdS via close-space sublimation is used to study the effect of window size (2 μm and 300 nm) on grain growth. The basic fabrication procedures for each of the layers (CdS, SiO2, and CdTe) and for achieving selective-area growth are presented. Selective-area growth of both micro- and nano-scale CdTe islands on CdS substrates using close-spaced sublimation is demonstrated. Scanning electron microscopy and electron backscatter diffraction microstructure analysis show that the micro-scale CdTe islands remain polycrystalline. However, when the island size is reduced to 300 nm, single crystal CdTe can be achieved within the windows. The CdTe grains were most often in the (101) orientation for both the micro- and nano-sized CdTe islands.

  14. Cadmium sulfide thin films deposited by close spaced sublimation and cadmium sulfide/cadmium telluride solar cells

    NASA Astrophysics Data System (ADS)

    Marinskiy, Dmitriy Nikolaevich

    1998-12-01

    One of the applications of CdS films is as a window layer in CdTe and Cu(In,Ga)Sesb2 solar cells. The study of the optical and structural properties of CdS films deposited by close spaced sublimation as well as their influence on CdS/CdTe solar cell performance is part of the CdTe solar cell program at the University of South Florida. CdS films have been deposited by the close-spaced sublimation technique. The influence of the main process parameters, the substrate and source temperatures, and the ambient in the deposition chamber has been investigated. As-deposited films have been subjected to heat treatments in Hsb2 ambient, in CdClsb2 atmosphere, and in atmosphere with small amounts of oxygen. A special annealing chamber was built to carry out the annealing experiments in the presence of CdClsb2 vapor and oxygen. Several CSS chambers were assembled to study the influence of various process parameters simultaneously and validate the results. Results of scanning electron microscopy and photoluminescence measurements have been used as the primary characterization techniques. X-ray diffraction, electron microprobe analysis, and transmission measurements have also been carried out. It was found that as deposited CdS films have a hexagonal structure independent of the process parameters used. The presence of a CdO phase was detected in the samples grown with the highest oxygen concentration in the ambient. The resistivity of CdS films is controlled by intergrain barriers. Photoluminescence measurements showed the presence of oxygen-acceptor transition and a wide variation in the intensity of deep emission bands. The variation in the intensities was correlated with the variation in the deposition and annealing conditions. However, no correlation was found between the PL intensities of defect bands and cell performance. CdS/CdTe junctions have been fabricated using standard deposition and postgrowth techniques developed in the USF solar cells laboratory. All cells have

  15. Sublimation extraction coupled with gas chromatography-mass spectrometry: A new technique for future in situ analyses of purines and pyrimidines on Mars

    NASA Astrophysics Data System (ADS)

    Glavin, D. P.; Cleaves, H. J.; Buch, A.; Schubert, M.; Aubrey, A.; Bada, J. L.; Mahaffy, P. R.

    2006-12-01

    We have developed a sublimation technique coupled with chemical derivatization and gas chromatography mass spectrometry (GC-MS) to detect nucleobases and other volatile organic compounds derived from bacteria in Mars analog materials. To demonstrate this technique, a sample of serpentine inoculated with Escherichia coli ( E. coli) cells was heated to 500 °C for several seconds under Martian ambient pressure. The sublimate was collected on a cold finger, then derivatized and analyzed by GC-MS. We found that adenine, cytosine, thymine and uracil were the most abundant molecules detected in the sublimed E. coli extract by GC-MS. In addition, nucleobases were also detected in sublimed extracts of a deep-sea sediment sample, seawater, and soil collected from the Atacama Desert in Chile after heating the samples under the same conditions. Our results indicate that nucleobases can be easily isolated directly from natural samples using sublimation and then detected by GC-MS after chemical derivatization. The sublimation-based extraction technique is one approach that should be considered for use by future in situ instruments designed to detect organic compounds relevant to life in the Martian regolith.

  16. Effects of interfacial interaction potential on the sublimation rates of TNT films on a silica surface examined by QCM and AFM techniques

    NASA Astrophysics Data System (ADS)

    Mu, R.; Ueda, A.; Liu, Y. C.; Wu, M.; Henderson, D. O.; Lareau, R. T.; Chamberlain, R. T.

    2003-04-01

    The study of 2,4,6-trinitrotoluene (TNT) sublimation rates from the bulk surface and a substrate surface have been evaluated quantitatively with both atomic force microscopy and quartz crystal microbalance (QCM) techniques. A first principle theoretical model is proposed, which allows obtaining three critical parameters, bulk sublimation rate, surface interaction potential, and the effective decay length, with no arbitrary parameters. The bulk sublimation rate predicted by the model is quantitatively confirmed by QCM experiments. The isothermal measurements with QCM showed that the sublimation activation energy of bulk TNT is 131 kJ/mol. More importantly, all results were obtained at one atmosphere and near room temperature. Thus, it should have direct impacts on explosive trace detection device applications.

  17. In-Situ Growth of Yb2O3 Layer for Sublimation Suppression for Yb14MnSb11 Thermoelectric Material for Space Power Applications

    NASA Technical Reports Server (NTRS)

    Nesbitt, James A.; Opila, Elizabeth J.; Nathal, Michael V.

    2012-01-01

    The compound Yb14MnSb11 is a p-type thermoelectric material of interest to the National Aeronautics and Space Administration (NASA) as a candidate replacement for the state-of-the-art Si-Ge used in current radioisotope thermoelectric generators (RTGs). Ideally, the hot end of this leg would operate at 1000 C in the vacuum of space. Although Yb14MnSb11 shows the potential to double the value of the thermoelectric figure of merit (zT) over that of Si-Ge at 1000 C, it suffers from a high sublimation rate at elevated temperatures and would require a coating in order to survive the required RTG lifetime of 14 years. The purpose of the present work is to measure the sublimation rate of Yb14MnSb11 and to investigate sublimation suppression for this material. This paper reports on the sublimation rate of Yb14MnSb11 at 1000 C (approximately 3 x 10(exp -3) grams per square centimeter hour) and efforts to reduce the sublimation rate with an in situ grown Yb2O3 layer. Despite the success in forming thin, dense, continuous, and adherent oxide scales on Yb14MnSb11, the scales did not prove to be sublimation barriers.

  18. In Situ Growth of a Yb2O3 Layer for Sublimation Suppression for Yb14MnSb11 Thermoelectric Material for Space Power Applications

    NASA Astrophysics Data System (ADS)

    Nesbitt, James A.; Opila, Elizabeth J.; Nathal, Michael V.

    2012-06-01

    The compound Yb14MnSb11 is a p-type thermoelectric material of interest to the National Aeronautics and Space Administration (NASA) as a candidate replacement for the state-of-the-art Si-Ge used in current radioisotope thermoelectric generators (RTGs). Ideally, the hot end of this leg would operate at 1000°C in the vacuum of space. Although Yb14MnSb11 shows the potential to double the value of the thermoelectric figure of merit ( zT) over that of Si-Ge at 1000°C, it suffers from a high sublimation rate at elevated temperatures and would require a coating in order to survive the required RTG lifetime of 14 years. The purpose of the present work is to measure the sublimation rate of Yb14MnSb11 and to investigate sublimation suppression for this material. This paper reports on the sublimation rate of Yb14MnSb11 at 1000°C (˜3 × 10-3 g/cm2 h) and efforts to reduce the sublimation rate with an in situ grown Yb2O3 layer. Despite the success in forming thin, dense, continuous, and adherent oxide scales on Yb14MnSb11, the scales did not prove to be sublimation barriers.

  19. Physical chemistry of freeze-drying: measurement of sublimation rates for frozen aqueous solutions by a microbalance technique.

    PubMed

    Pikal, M J; Shah, S; Senior, D; Lang, J E

    1983-06-01

    The sublimation rate of frozen solutions was studied as a function of freezing rate, thickness of dried product (l), temperature, residual air pressure, and solute concentration. Data are presented for pure water, aqueous potassium chloride, aqueous povidone, and aqueous dobutamine hydrochloride-mannitol (System I). The resistance of the dried product to water vapor flow (Rp) was evaluated from the sublimation rate and the sample temperature. The primary experimental technique was based on freeze-drying a cylindrical microsample isothermally, with the sample suspended from one arm of a vacuum microbalance. Methodology to evaluate resistance data from vial freeze-drying experiments is also described. In separate experiments, samples in the form of a thin (15-microns) film were visually observed through a microscope during freeze-drying. Freeze-drying of most samples appeared to occur by water vapor escaping through open channels created by prior sublimation of ice. Contrary to the usual theoretical model, Rp is neither independent of temperature nor directly proportional to l. Rather, Rp decreases with increasing temperature and the l dependence is normally of the form Rp = (A0 + A1l)/(1 + A2l), where Ai (i = 0, 1, 2) are constants. In several cases, Rp is very large near l = 0, decreases sharply at l congruent to 0.1 cm, and obeys the above equation where l greater than 0.2 cm, a result suggesting an amorphous surface skin which cracks on desorption of water. The temperature dependence of Rp suggests that, as the sample temperature approaches the eutectic (or collapse) temperature, hydrodynamic surface flow of adsorbed water is an important flow mechanism. PMID:6875825

  20. Influence of substrate temperature on structural and optical properties of bismuth oxide thin films deposited by close-spaced vacuum sublimation

    NASA Astrophysics Data System (ADS)

    Ivashchenko, M. M.; Buryk, I. P.; Latyshev, V. M.; Stepanenko, A. O.; Levchenko, K. S.

    2015-12-01

    Bi2O3 thin films were deposited on ultrasonically-cleaned glass and mica substrates by close-spaced vacuum sublimation technique. Films surface morphology was studied using scanning electron microscopy (SEM). Structural study based on the transmission-electron microscopy (TEM) and selected-area electron diffraction (SAED) analysis has been shown that deposited films were polycrystalline with face-centered cubic structure. Optical study was carried out by spectral photometry analysis in the wavelengths range λ = 320-900 nm using the optical transmittance and absorbance measurements. For determination optical band gap Eg the Tauc plot was used and the band gap energy Eg is determined in the range of 3.50-3.62 eV, respectively. Fourier-transform infra-red (FTIR) analysis shown that obtained films are well-crystalline and have a good optical quality.

  1. The role of oxygen in CdS/CdTe solar cells deposited by close-spaced sublimation

    SciTech Connect

    Rose, D.H.; Levi, D.H.; Matson, R.J.

    1996-05-01

    The presence of oxygen during close-spaced sublimation (CSS) of CdTe has been previously reported to be essential for high-efficiency CdS/CdTe solar cells because it increases the acceptor density in the absorber. The authors find that the presence of oxygen during CSS increases the nucleation site density of CdTe, thus decreasing pinhole density and grain size. Photoluminescence showed that oxygen decreases material quality in the bulk of the CdTe film, but positively impacts the critical CdS/CdTe interface. Through device characterization the authors were unable to verify an increase in acceptor density with increased oxygen. These results, along with the achievement of high-efficiency cells (13% AM1.5) without the use of oxygen, led the authors to conclude that the use of oxygen during CSS deposition of CdTe can be useful but is not essential.

  2. Epitaxial Growth of High-Resistivity CdTe Thick Films Grown Using a Modified Close Space Sublimation Method

    NASA Astrophysics Data System (ADS)

    Jiang, Quanzhong; Brinkman, Andy W.; Veeramani, Perumal; Sellin, Paul. J.

    2010-02-01

    This paper reports the growth of high-resistivity CdTe thick epitaxial films of single crystal nature using a modified close space sublimation method (MCSS) in a Te-rich environment. We propose that the high Te2 partial pressure results in an increased concentration of TeCd antisites acting as deep donors to produce the high-resistivity CdTe, as well as improved quality of thick films. This is in agreement with the deep-donor model introduced by Fiderele et al. [Cryst. Res. Technol. 38 (2003) 588]. The thick films have a µeτe value in the order 10-4 cm2 V-1 and as expected, the TeCd antisites appeared not to act as electron traps.

  3. In-Space Propulsion Engine Architecture Based on Sublimation of Planetary Resources: From Exploration Robots to NED Mitigation

    NASA Technical Reports Server (NTRS)

    Sibille, Laurent; Mantovani, James G.

    2011-01-01

    Volatile solids occur naturally on most planetary bodies including the Moon, Mars, asteroids and comets. Examples of recent discoveries include water ice, frozen carbon dioxide and hydrocarbons. The ability to utilize readily available resources for in-space propulsion and for powering surface systems during a planetary mission will help minimize the overall cost and extend the op.erational life of a mission. The utilization of volatile solids to achieve these goals is attractive for its simplicity. We have investigated the potential of subliming in situ volatiles and silicate minerals to power propulsion engines for a wide range of in-space applications where environmental conditions are favorable. This paper addresses the' practicality of using planetary solid volatiles as a power source for propulsion and surface systems by presenting results of modeling involving thermodynamic and physical mechanics calculations, and laboratory testing to measure the thrust obtained from ,a volatile solid engine (VSE). Applications of a VSE for planetary exploration are discussed as a means for propulsion and for mechanical actuators and surface mobility platforms.

  4. X-38 Advanced Sublimator

    NASA Technical Reports Server (NTRS)

    Dingell, Chuck; Quintana, Clemente; Le, Suy; Hafemalz, David S.; Clark, Mike; Cloutier, Robert

    2009-01-01

    A document discusses a heat rejection device for transferring heat from a space vehicle by venting water into space through the use of a novel, two-stage water distribution system. The system consists of two different, porous media that stop water-borne contaminants from clogging the system and causing operational failures. Feedwater passes through a small nozzle, then into a porous disk made of sintered stainless steel, and then finally into large-pore aluminum foam. The smaller pore layer of the steel disk controls the pressure drop of the feedwater. The ice forms in the foam layer, and then sublimates, leaving any contaminants behind. The pore-size of the foam is two orders of magnitude larger than the current porous plate sublimators, allowing for a greater tolerance for contaminants. Using metallic fibers in the foam also negates problems with compression seen in the use of poly(tetrafluoroethylene) felt.

  5. Characterization of CdMnTe films deposited from polycrystalline powder source using closed-space sublimation method

    SciTech Connect

    Lai, Jianming; Wang, Junnan; Wang, Lin; Ji, Huanhuan; Xu, Run; Zhang, Jijun; Huang, Jian; Shen, Yue; Min, Jiahua; Wang, Linjun Xia, Yiben

    2015-09-15

    CdMnTe films were prepared on quartz substrates by closed-space sublimation of polycrystalline Cd{sub 0.74}Mn{sub 0.26}Te powders. This was performed at different substrate temperatures (T{sub s} = 200, 300, 350, and 400 °C). The interfacial adhesion strength between the films and substrates, when fabricated from polycrystalline powders, was greater than that of films grown using a bulk source. X-ray diffraction studies revealed that the as-deposited films had a zinc blende structure with a preferential (111) orientation. Precipitation of Te occurred in the films deposited at T{sub s} = 200 °C, as confirmed using scanning electron microscopy, x-ray diffraction, and Raman spectroscopy. The growth mode and re-evaporation dependence on the value of T{sub s} of the films were investigated. Our results suggested that materials suitable for radiation detection can be grown from a powder source at lower substrate temperatures then when grown from a bulk source.

  6. Optical and electrical characterizations of highly efficient CdTe thin film solar cells prepared by close-spaced sublimation

    NASA Astrophysics Data System (ADS)

    Okamoto, T.; Yamada, A.; Konagai, M.

    2000-06-01

    The effects of the Cu diffusion on the optical and electrical properties of CdTe thin film solar cells prepared by close-spaced sublimation (CSS) were investigated by capacitance-voltage ( C- V) measurement and low-temperature photoluminescence (PL) measurement. C- V measurement revealed that the net acceptor concentration in the CdTe layer was independent of the heat treatment after screen printing of the Cu-doped graphite electrode for Cu diffusion into the CdTe layer, although it greatly affected the solar cell performance. Furthermore, the depth profile of PL spectrum of CdTe layer implies that the heat treatment for Cu diffusion facilitates the formation of low-resistance contact to CdTe through the formation of a heavily doped (p +) region in the CdTe adjacent to the back electrode, but Cu atoms do not act as effective acceptors in the CdTe layer except the region near the back electrode.

  7. A sublimation heat engine

    NASA Astrophysics Data System (ADS)

    Wells, Gary G.; Ledesma-Aguilar, Rodrigo; McHale, Glen; Sefiane, Khellil

    2015-03-01

    Heat engines are based on the physical realization of a thermodynamic cycle, most famously the liquid-vapour Rankine cycle used for steam engines. Here we present a sublimation heat engine, which can convert temperature differences into mechanical work via the Leidenfrost effect. Through controlled experiments, quantified by a hydrodynamic model, we show that levitating dry-ice blocks rotate on hot turbine-like surfaces at a rate controlled by the turbine geometry, temperature difference and solid material properties. The rotational motion of the dry-ice loads is converted into electric power by coupling to a magnetic coil system. We extend our concept to liquid loads, generalizing the realization of the new engine to both sublimation and the instantaneous vapourization of liquids. Our results support the feasibility of low-friction in situ energy harvesting from both liquids and ices. Our concept is potentially relevant in challenging situations such as deep drilling, outer space exploration or micro-mechanical manipulation.

  8. The Sublime and Education

    ERIC Educational Resources Information Center

    Carson, Jamin

    2006-01-01

    The sublime is a theory of aesthetics that reached its highest popularity in British literature during the Romantic period (c. 1785-1832). This article (1) explicates philosophers' different meanings of the sublime; (2) show how the sublime is relevant to education; and (3) show how the sublime "works" in literature by analyzing William Blake's…

  9. First-order feasibility analysis of a space suit radiator concept based on estimation of water mass sublimation using Apollo mission data

    NASA Astrophysics Data System (ADS)

    Metts, Jonathan G.; Klaus, David M.

    2012-01-01

    Thermal control of a space suit during extravehicular activity (EVA) is typically accomplished by sublimating water to provide system cooling. Spacecraft, on the other hand, primarily rely on radiators to dissipate heat. Integrating a radiator into a space suit has been proposed as an alternative design that does not require mass consumption for heat transfer. While providing cooling without water loss offers potential benefits for EVA application, it is not currently practical to rely on a directional, fixed-emissivity radiator to maintain thermal equilibrium of a spacesuit where the radiator orientation, environmental temperature, and crew member metabolic heat load fluctuate unpredictably. One approach that might make this feasible, however, is the use of electrochromic devices that are capable of infrared emissivity modulation and can be actively controlled across the entire suit surface to regulate net heat flux for the system. Integrating these devices onto the irregular, compliant space suit material requires that they be fabricated on a flexible substrate, such as Kapton film. An initial assessment of whether or not this candidate technology presents a feasible design option was conducted by first characterizing the mass of water loss from sublimation that could theoretically be saved if an electrochromic suit radiator was employed for thermal control. This is particularly important for lunar surface exploration, where the expense of transporting water from Earth is excessive, but the technology is potentially beneficial for other space missions as well. In order to define a baseline for this analysis by comparison to actual data, historical documents from the Apollo missions were mined for comprehensive, detailed metabolic data from each lunar surface outing, and related data from NASA's more recent "Advanced Lunar Walkback" tests were also analyzed. This metabolic database was then used to validate estimates for sublimator water consumption during surface

  10. A close-space sublimation driven pathway for the manipulation of substrate-supported micro- and nanostructures

    NASA Astrophysics Data System (ADS)

    Sundar, Aarthi

    The ability to fabricate structures and engineer materials on the nanoscale leads to the development of new devices and the study of exciting phenomena. Nanostructures attached to the surface of a substrate, in a manner that renders them immobile, have numerous potential applications in a diverse number of areas. Substrate-supported nanostructures can be fabricated using numerous modalities; however the easiest and most inexpensive technique to create a large area of randomly distributed particles is by the technique of thermal dewetting. In this process a metastable thin film is deposited at room temperature and heated, causing the film to lower its surface energy by agglomerating into droplet-like nanostructures. The main drawbacks of nanostructure fabrication via this technique are the substantial size distributions realized and the lack of control over nanostructure placement. In this doctoral dissertation, a new pathway for imposing order onto the thermal dewetting process and for manipulating the size, placement, shape and composition of preformed templates is described. It sees the confinement of substrate-supported thin films or nanostructure templates by the free surface of a metal film or a second substrate surface. Confining the templates in this manner and heating them to elevated temperatures leads to changes in the characteristics of the nanostructures formed. Three different modalities are demonstrated which alters the preformed structures by: (i) subtracting atoms from the templates, (ii) adding atoms to the template or (iii) simultaneously adding and subtracting atoms. The ability to carry out such processes depends on the choice of the confining surface and the nanostructured templates used. A subtractive process occurs when an electroformed nickel mesh is placed in conformal contact with a continuous gold film while it dewets, resulting in the formation of a periodic array of gold microstructures on an oxide substrate surface. When heated the

  11. Experimental Investigation of Transient Sublimator Performance

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik B.; Stephen, Ryan A.; Leimkuehler, Thomas O.

    2010-01-01

    Sublimators have been used as heat rejection devices for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100%. However, sublimators are currently being considered to operate in a cyclical topping mode, which represents a new mode of operation for sublimators. Sublimators can be used as a topper during mission phases such as low lunar or low earth orbit. In these mission phases, the sublimator will be repeatedly started and stopped during each orbit to provide supplemental heat rejection for the portion of the orbit where the radiative sink temperature exceeds the system setpoint temperature. This paper will investigate the effects of these transient starts and stops on the feedwater utilization during various feedwater timing scenarios. The X-38 sublimator and Contamination Insensitive Sublimator (CIS) were tested in a ground vacuum chamber to understand this behavior and to quantify the feedwater performance. Data from various scenarios will be analyzed to investigate feedwater utilization under the cyclical conditions. This paper will also provide recommendations for future sublimator designs and/or feedwater control.

  12. A sublimation heat engine

    PubMed Central

    Wells, Gary G.; Ledesma-Aguilar, Rodrigo; McHale, Glen; Sefiane, Khellil

    2015-01-01

    Heat engines are based on the physical realization of a thermodynamic cycle, most famously the liquid–vapour Rankine cycle used for steam engines. Here we present a sublimation heat engine, which can convert temperature differences into mechanical work via the Leidenfrost effect. Through controlled experiments, quantified by a hydrodynamic model, we show that levitating dry-ice blocks rotate on hot turbine-like surfaces at a rate controlled by the turbine geometry, temperature difference and solid material properties. The rotational motion of the dry-ice loads is converted into electric power by coupling to a magnetic coil system. We extend our concept to liquid loads, generalizing the realization of the new engine to both sublimation and the instantaneous vapourization of liquids. Our results support the feasibility of low-friction in situ energy harvesting from both liquids and ices. Our concept is potentially relevant in challenging situations such as deep drilling, outer space exploration or micro-mechanical manipulation. PMID:25731669

  13. A sublimation heat engine.

    PubMed

    Wells, Gary G; Ledesma-Aguilar, Rodrigo; McHale, Glen; Sefiane, Khellil

    2015-01-01

    Heat engines are based on the physical realization of a thermodynamic cycle, most famously the liquid-vapour Rankine cycle used for steam engines. Here we present a sublimation heat engine, which can convert temperature differences into mechanical work via the Leidenfrost effect. Through controlled experiments, quantified by a hydrodynamic model, we show that levitating dry-ice blocks rotate on hot turbine-like surfaces at a rate controlled by the turbine geometry, temperature difference and solid material properties. The rotational motion of the dry-ice loads is converted into electric power by coupling to a magnetic coil system. We extend our concept to liquid loads, generalizing the realization of the new engine to both sublimation and the instantaneous vapourization of liquids. Our results support the feasibility of low-friction in situ energy harvesting from both liquids and ices. Our concept is potentially relevant in challenging situations such as deep drilling, outer space exploration or micro-mechanical manipulation. PMID:25731669

  14. Investigation of Transient Performance for a Sublimator

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik B.; Stephan, Ryan A.; Leimkuehler, Thomas O.

    2010-01-01

    Sublimators have been used as heat rejection devices for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100 %. However, Sublimators are currently being considered to operate in a cyclical topping mode during low lunar orbit for Altair and possibly Orion. The cyclical topping mode represents a new mode of operation for sublimators. In this operational mode, the sublimator will be repeatedly started and stopped during each orbit to provide supplemental heat rejection for the portion of the orbit where the radiative sink temperature exceeds the system setpoint temperature. This paper will investigate the effects of these transient starts and stops on the feedwater utilization for various feedwater timing scenarios.

  15. Investigation of Transient Performance for a Sublimator

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Sheth, Rubik; Stephan, Ryan A.

    2009-01-01

    Sublimators have been used as heat rejection devices for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100%. However, sublimators are currently being considered to operate in a cyclical topping mode during low lunar orbit for Altair and possibly Orion, which represents a new mode of operation for sublimators. In this mission phase, the sublimator will be repeatedly started and stopped during each orbit to provide supplemental heat rejection for the portion of the orbit where the sink temperature exceeds the system setpoint temperature. This paper will investigate the effects of these transient starts and stops on the feedwater utilization during various feedwater timing scenarios. The X-38 sublimator, which represents the state of the art in sublimator technology, was used to understand this behavior and to quantify the feedwater performance. Data from various scenarios will be analyzed to investigate feedwater utilization under the cyclical conditions. This paper will also provide recommendations for future sublimator designs and/or feedwater control.

  16. Investigation of Transient Performance for a Sublimator

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik B.; Stephan, Ryan A.; Leimkuehler, Thomas O.

    2011-01-01

    Sublimators have been used as heat rejection devices for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100%. However, sublimators are currently being considered to operate in a cyclical topping mode, which represents a new mode of operation for sublimators. Sublimators can be used as a topper during mission phases such as low lunar or low earth orbit. In these mission phases, the sublimator will be repeatedly started and stopped during each orbit to provide supplemental heat rejection for the portion of the orbit where the radiative sink temperature exceeds the system setpoint temperature. This paper will investigate the effects of these transient starts and stops on the feedwater utilization during various feedwater timing scenarios. The X-38 sublimator and Contamination Insensitive Sublimator (CIS) were tested in a ground vacuum chamber to understand this behavior and to quantify the feedwater performance. Data from various scenarios will be analyzed to investigate feedwater utilization under the cyclical conditions

  17. Transport phenomena in the close-spaced sublimation deposition process for manufacture of large-area cadmium telluride photovoltaic panels: Modeling and optimization

    NASA Astrophysics Data System (ADS)

    Malhotra, C. P.

    With increasing national and global demand for energy and concerns about the effect of fossil fuels on global climate change, there is an increasing emphasis on the development and use of renewable sources of energy. Solar cells or photovoltaics constitute an important renewable energy technology but the major impediment to their widespread adoption has been their high initial cost. Although thin-film photovoltaic semiconductors such as cadmium sulfide-cadmium telluride (CdS/CdTe) can potentially be inexpensively manufactured using large area deposition techniques such as close-spaced sublimation (CSS), their low stability has prevented them from becoming an alternative to traditional polycrystalline silicon solar cells. A key factor affecting the stability of CdS/CdTe cells is the uniformity of deposition of the thin films. Currently no models exist that can relate the processing parameters in a CSS setup with the film deposition uniformity. Central to the development of these models is a fundamental understanding of the complex transport phenomena which constitute the deposition process which include coupled conduction and radiation as well as transition regime rarefied gas flow. This thesis is aimed at filling these knowledge gaps and thereby leading to the development of the relevant models. The specific process under consideration is the CSS setup developed by the Materials Engineering Group at the Colorado State University (CSU). Initially, a 3-D radiation-conduction model of a single processing station was developed using the commercial finite-element software ABAQUS and validated against data from steady-state experiments carried out at CSU. A simplified model was then optimized for maximizing the steady-state thermal uniformity within the substrate. It was inferred that contrary to traditional top and bottom infrared lamp heating, a lamp configuration that directs heat from the periphery of the sources towards the center results in the minimum temperature

  18. Investigation of induced recrystallization and stress in close-spaced sublimated and radio-frequency magnetron sputtered CdTe thin films

    SciTech Connect

    Moutinho, H.R.; Dhere, R.G.; Al-Jassim, M.M.; Levi, D.H.; Kazmerski, L.L.

    1999-07-01

    We have induced recrystallization of small grain CdTe thin films deposited at low temperatures by close-spaced sublimation (CSS), using a standard CdCl{sub 2} annealing treatment. We also studied the changes in the physical properties of CdTe films deposited by radio-frequency magnetron sputtering after the same post-deposition processing. We demonstrated that the effects of CdCl{sub 2} on the physical properties of CdTe films are similar, and independent of the deposition method. The recrystallization process is linked directly to the grain size and stress in the films. These studies indicated the feasibility of using lower-temperature processes in fabricating efficient CSS CdTe solar cells. We believe that, after the optimization of the parameters of the chemical treatment, these films can attain a quality similar to CSS films grown using current standard conditions. {copyright} {ital 1999 American Vacuum Society.}

  19. Heat rejection sublimator

    NASA Technical Reports Server (NTRS)

    Dingell, Charles W. (Inventor); Quintana, Clemente E. (Inventor); Le, Suy (Inventor); Clark, Michael R. (Inventor); Cloutier, Robert E. (Inventor); Hafermalz, David Scott (Inventor)

    2009-01-01

    A sublimator includes a sublimation plate having a thermal element disposed adjacent to a feed water channel and a control point disposed between at least a portion of the thermal element and a large pore substrate. The control point includes a sintered metal material. A method of dissipating heat using a sublimator includes a sublimation plate having a thermal element and a control point. The thermal element is disposed adjacent to a feed water channel and the control point is disposed between at least a portion of the thermal element and a large pore substrate. The method includes controlling a flow rate of feed water to the large pore substrate at the control point and supplying heated coolant to the thermal element. Sublimation occurs in the large pore substrate and the controlling of the flow rate of feed water is independent of time. A sublimator includes a sublimation plate having a thermal element disposed adjacent to a feed water channel and a control point disposed between at least a portion of the thermal element and a large pore substrate. The control point restricts a flow rate of feed water from the feed water channel to the large pore substrate independent of time.

  20. Experimental Investigation of Transient Sublimator Performance

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik B.; Stephan, Ryan A.; Leimkuehler, Thomas O.

    2012-01-01

    Sublimators have been used as heat rejection devices for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100%. However, sublimators are currently being considered for operations in a cyclical topping mode, which represents a new mode of operation for sublimators. Sublimators can be used as a supplemental heat rejection device during mission phases where the environmental temperature or heat rejection requirement changes rapidly. This scenario may occur during low lunar orbit, low earth orbit, or other planetary orbits. In these mission phases, the need for supplemental heat rejection will vary between zero and some fraction of the overall heat load. In particular, supplemental heat rejection is required for the portion of the orbit where the radiative sink temperature exceeds the system setpoint temperature. This paper will describe the effects of these transient starts and stops on the feedwater utilization during various feedwater timing scenarios. Experimental data from various scenarios is analyzed to investigate feedwater consumption efficiency under the cyclical conditions. Start up utilization tests were conducted to better understand the transient performance. This paper also provides recommendations for future sublimator design and transient operation.

  1. Structural and optical properties of AgAlTe{sub 2} layers grown on sapphire substrates by closed space sublimation method

    SciTech Connect

    Uruno, A. Usui, A.; Kobayashi, M.

    2014-11-14

    AgAlTe{sub 2} layers were grown on a- and c-plane sapphire substrates using a closed space sublimation method. Grown layers were confirmed to be single phase layers of AgAlTe{sub 2} by X-ray diffraction. AgAlTe{sub 2} layers were grown to have a strong preference for the (112) orientation on both kinds of substrates. The variation in the orientation of grown layers was analyzed in detail using the X-ray diffraction pole figure measurement, which revealed that the AgAlTe{sub 2} had a preferential epitaxial relationship with the c-plane sapphire substrate. The atomic arrangement between the (112) AgAlTe{sub 2} layer and sapphire substrates was compared. It was considered that the high order of the lattice arrangement symmetry probably effectively accommodated the lattice mismatch. The optical properties of the grown layer were also evaluated by transmittance measurements. The bandgap energy was found to be around 2.3 eV, which was in agreement with the theoretical bandgap energy of AgAlTe{sub 2}.

  2. Management Styles and Techniques: Space.

    ERIC Educational Resources Information Center

    Montanelli, Dale S.; And Others

    1987-01-01

    Two articles discuss the management of space in library facilities. The first focuses on three general aspects of space management: how to organize for space management; necessary data collection; and human factors. The second article focuses specifically on space requirements for library technical processes. (CLB)

  3. Coating Thermoelectric Devices To Suppress Sublimation

    NASA Technical Reports Server (NTRS)

    Sakamoto, Jeffrey; Caillat, Thierry; Fleurial, Jean-Pierre; Snyder, G. Jeffrey

    2007-01-01

    A technique for suppressing sublimation of key elements from skutterudite compounds in advanced thermoelectric devices has been demonstrated. The essence of the technique is to cover what would otherwise be the exposed skutterudite surface of such a device with a thin, continuous film of a chemically and physically compatible metal. Although similar to other sublimation-suppression techniques, this technique has been specifically tailored for application to skutterudite antimonides. The primary cause of deterioration of most thermoelectric materials is thermal decomposition or sublimation - one or more elements sublime from the hot side of a thermoelectric couple, changing the stoichiometry of the device. Examples of elements that sublime from their respective thermoelectric materials are Ge from SiGe, Te from Pb/Te, and now Sb from skutterudite antimonides. The skutterudite antimonides of primary interest are CoSb3 [electron-donor (n) type] and CeFe(3-x)Co(x)Sb12 [electron-acceptor (p) type]. When these compounds are subjected to typical operating conditions [temperature of 700 C and pressure <10(exp -5) torr (0.0013 Pa)], Sb sublimes from their surfaces, with the result that Sb depletion layers form and advance toward their interiors. As the depletion layer advances in a given device, the change in stoichiometry diminishes the thermal-to-electric conversion efficiency of the device. The problem, then, is to prevent sublimation, or at least reduce it to an acceptably low level. In preparation for an experiment on suppression of sublimation, a specimen of CoSb3 was tightly wrapped in a foil of niobium, which was selected for its chemical stability. In the experiment, the wrapped specimen was heated to a temperature of 700 C in a vacuum of residual pressure <10(exp -5) torr (0.0013 Pa), then cooled and sectioned. Examination of the sectioned specimen revealed that no depletion layer had formed, indicating the niobium foil prevented sublimation of antimony at 700 C

  4. Experimental Investigation of Sublimator Performance at Transient Heat Loads

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik B.; Stephen, Ryan A.; Leimkuehler, Thomas O.

    2011-01-01

    Sublimators have been used as heat rejection devices for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100%. However, sublimators are currently being considered to operate in a cyclical topping mode, which represents a new mode of operation for sublimators. Sublimators can be used as a topper during mission phases such as low lunar or low earth orbit. In these mission phases, the sublimator will be repeatedly started and stopped during each orbit to provide supplemental heat rejection for the portion of the orbit where the radiative sink temperature exceeds the system setpoint temperature. This paper will summarize the effort put into understanding sublimator response under a transient heat load. The performance will be assessed by detailing the changes in feedwater utilization due to transient starts and stops during various feedwater timing scenarios. Sublimator start up utilization will be assessed as a possible relationship to transient performance of a sublimator. This paper will also provide recommendations for future sublimator designs and/or feedwater control.

  5. Ultrasound Techniques for Space Applications

    NASA Technical Reports Server (NTRS)

    Rooney, James A.

    1985-01-01

    Ultrasound has proven to be a safe non-invasive technique for imaging organs and measuring cardiovascular function. It has unique advantages for application to problems with man in space including evaluation of cardiovascular function both in serial studies and during critical operations. In addition, specialized instrumentation may be capable of detecting the onset of decompression sickness during EVA activities. A spatial location and three-dimensional reconstruction system is being developed to improve the accuracy and reproducibility for serial comparative ultrasound studies of cardiovascular function. The three-dimensional method permits the acquisition of ultrasonic images from many views that can be recombined into a single reconstruction of the heart or vasculature. In addition to conventional imaging and monitoring systems, it is sometimes necessary or desirable to develop instrumentation for special purposes. One example of this type of development is the design of a pulsed-Doppler system to monitor cerebral blood flow during critical operations such as re-entry. A second example is the design of a swept-frequency ultrasound system for the detection of bubbles in the circulatory system and/or soft tissues as an early indication of the onset of decompression sickness during EVA activities. This system exploits the resonant properties of bubbles and can detect both fundamental and second harmonic emissions from the insonified region.

  6. In-Space Propulsion Engine Architecture Based on Sublimation of Planetary Resources: From Exploration Robots to NED Mitigation

    NASA Technical Reports Server (NTRS)

    Sibille, Laurent; Mantovani, James; Dominquez, Jesus

    2011-01-01

    The purpose of this NIAC study is to identify those volatile and mineral resources that are available on asteroids, comets, moons and planets in the solar system, and investigate methods to transform these resources into forms of power that will expand the capabilities of future robotic and human exploration missions to explore planetary bodies beyond the Moon and will mitigate hazards from NEOs. The sources of power used for deep space probe missions are usually derived from either solar panels for electrical energy, radioisotope thermal generators for thermal energy, or fuel cells and chemical reactions for chemical energy and propulsion.

  7. Modular Porous Plate Sublimator /MPPS/ requires only water supply for coolant

    NASA Technical Reports Server (NTRS)

    Rathbun, R. J.

    1966-01-01

    Modular porous plate sublimators, provided for each location where heat must be dissipated, conserve the battery power of a space vehicle by eliminating the coolant pump. The sublimator requires only a water supply for coolant.

  8. [Spectral analyzing effects of atmosphere states on the structure and characteristics of CdTe polycrystalline thin films made by close-spaced sublimation].

    PubMed

    Zheng, Hua-jing; Zheng, Jia-gui; Feng, Liang-huan; Zhang, Jing-quan; Xie, Er-qing

    2005-07-01

    The structure and characteristics of CdTe thin films are dependent on the working atmosphere states in close-spaced sublimation. In the present paper, CdTe polycrystalline thin films were deposited by CSS in mixture atmosphere of argon and oxygen. The physical mechanism of CSS was analyzed, and the temperature distribution in CSS system was measured. The dependence of preliminary nucleus creation on the atmosphere states (involving component and pressure) was studied. Transparencies were measured and optic energy gaps were calculated. The results show that: (1) The CdTe films deposited in different atmospheres are cubic structure. With increasing oxygen concentration, a increases and reaches the maximum at 6% oxygen concentration, then reduces, and increases again after passing the point at 12% oxygen concentration. Among them, the sample depositing at 9% oxygen concentration is the best. The optic energy gaps are 1.50-1.51 eV for all CdTe films. (2) The samples depositing at different pressures at 9% oxygen concentration are all cubical structure of CdTe, and the diffraction peaks of CdS and SnO2:F still appear. With the gas pressure increasing, the crystal size of CdTe minishes, the transparency of the thin film goes down, and the absorption side shifts to the short-wave direction. (3) The polycrystalline thin films with high quality deposit in 4 minutes under the depositing condition that the substrate temperature is 550 degrees C, and source temperature is 620 degrees C at 9% oxygen concentration. PMID:16241058

  9. Sublimation, culture, and creativity.

    PubMed

    Kim, Emily; Zeppenfeld, Veronika; Cohen, Dov

    2013-10-01

    Combining insights from Freud and Weber, this article explores whether Protestants (vs. Catholics and Jews) are more likely to sublimate their taboo feelings and desires toward productive ends. In the Terman sample (Study 1), Protestant men and women who had sexual problems related to anxieties about taboos and depravity had greater creative accomplishments, as compared to those with sexual problems unrelated to such concerns and to those reporting no sexual problems. Two laboratory experiments (Studies 2 and 3) found that Protestants produced more creative artwork (sculptures, poems, collages, cartoon captions) when they were (a) primed with damnation-related words, (b) induced to feel unacceptable sexual desires, or (c) forced to suppress their anger. Activating anger or sexual attraction was not enough; it was the forbidden or suppressed nature of the emotion that gave the emotion its creative power. The studies provide possibly the first experimental evidence for sublimation and suggest a cultural psychological approach to defense mechanisms. PMID:23834638

  10. EPR techniques for space biodosimetry

    SciTech Connect

    Haskell, E.; Hayes, R.; Kenner, G.; Sholom, S.; Chumak, V.

    1996-12-31

    Retrospective dosimetry of tooth enamel has become an increasingly complex and difficult discipline to undertake while still attaining accuracy. The paper provides a review of the major obstacles, advances and pertinent phenomenon associated with low level retrospective dosimetry of human tooth enamel. Also covered is the many sources of error in EPR dosimetry, their potential solutions, as well as the different analysis and scanning techniques in use with their prospective pros and cons. Prospective directions for new approaches, methods, and instruments are also reviewed.

  11. FPGAs in Space Environment and Design Techniques

    NASA Technical Reports Server (NTRS)

    Katz, Richard B.; Day, John H. (Technical Monitor)

    2001-01-01

    This viewgraph presentation gives an overview of Field Programmable Gate Arrays (FPGA) in the space environment and design techniques. Details are given on the effects of the space radiation environment, total radiation dose, single event upset, single event latchup, single event transient, antifuse technology and gate rupture, proton upsets and sensitivity, and loss of functionality.

  12. Optical Measurement Technique for Space Column Characterization

    NASA Technical Reports Server (NTRS)

    Barrows, Danny A.; Watson, Judith J.; Burner, Alpheus W.; Phelps, James E.

    2004-01-01

    A simple optical technique for the structural characterization of lightweight space columns is presented. The technique is useful for determining the coefficient of thermal expansion during cool down as well as the induced strain during tension and compression testing. The technique is based upon object-to-image plane scaling and does not require any photogrammetric calibrations or computations. Examples of the measurement of the coefficient of thermal expansion are presented for several lightweight space columns. Examples of strain measured during tension and compression testing are presented along with comparisons to results obtained with Linear Variable Differential Transformer (LVDT) position transducers.

  13. Prediction Techniques in Operational Space Weather Forecasting

    NASA Astrophysics Data System (ADS)

    Zhukov, Andrei

    2016-07-01

    The importance of forecasting space weather conditions is steadily increasing as our society is becoming more and more dependent on advanced technologies that may be affected by disturbed space weather. Operational space weather forecasting is still a difficult task that requires the real-time availability of input data and specific prediction techniques that are reviewed in this presentation, with an emphasis on solar and interplanetary weather. Key observations that are essential for operational space weather forecasting are listed. Predictions made on the base of empirical and statistical methods, as well as physical models, are described. Their validation, accuracy, and limitations are discussed in the context of operational forecasting. Several important problems in the scientific basis of predicting space weather are described, and possible ways to overcome them are discussed, including novel space-borne observations that could be available in future.

  14. Modelling Sublimation of Carbon Dioxide

    ERIC Educational Resources Information Center

    Winkel, Brian

    2012-01-01

    In this article, the author reports results in their efforts to model sublimation of carbon dioxide and the associated kinetics order and parameter estimation issues in their model. They have offered the reader two sets of data and several approaches to determine the rate of sublimation of a piece of solid dry ice. They presented several models…

  15. Development and Testing of the Contaminant Insensitive Sublimator

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Stephan, Ryan A.

    2007-01-01

    Sublimators have been used for heat rejection for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Some of the attractive features of sublimators are that they are compact, lightweight, and self-regulating. One of the drawbacks of previous designs has been sensitivity to non-volatile contamination in the feedwater, which can clog relatively small pores (approx. 3-6 micrometers) in the porous plates where ice forms and sublimates. A new design that is less sensitive to contaminants is being developed at the Johnson Space Center (JSC). This paper describes the design, fabrication, and testing of the Contaminant Insensitive Sublimator (CIS) Engineering Development Unit (EDU).

  16. Development and Testing of the Contaminant Insensitive Sublimator

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Stephan, Ryan A.; Westheimer, David T.

    2006-01-01

    Sublimators have been used for heat rejection for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Some of the attractive features of sublimators are that they are compact, lightweight, and self-regulating. One of the drawbacks of previous designs has been sensitivity to non-volatile contamination in the feedwater, which can clog relatively small pores (approx.3-6 microns) in the porous plates where ice forms and sublimates. A new design that is less sensitive to contaminants is being developed at the Johnson Space Center. This paper describes the design, fabrication, and testing of the Contaminant Insensitive Sublimator (CIS) Engineering Development Unit (EDU).

  17. Sublimation systems and associated methods

    DOEpatents

    Turner, Terry D.; McKellar, Michael G.; Wilding, Bruce M.

    2016-02-09

    A system for vaporizing and sublimating a slurry comprising a fluid including solid particles therein. The system includes a first heat exchanger configured to receive the fluid including solid particles and vaporize the fluid and a second heat exchanger configured to receive the vaporized fluid and solid particles and sublimate the solid particles. A method for vaporizing and sublimating a fluid including solid particles therein is also disclosed. The method includes feeding the fluid including solid particles to a first heat exchanger, vaporizing the fluid, feeding the vaporized fluid and solid particles to a second heat exchanger and sublimating the solid particles. In some embodiments the fluid including solid particles is liquid natural gas or methane including solid carbon dioxide particles.

  18. Ion composition measurement techniques for space plasmas

    NASA Technical Reports Server (NTRS)

    Gloeckler, George

    1990-01-01

    Plasmas found in space range from the solar wind with a typical temperature of 100,000-1,000,000 K, about 400 km/s bulk flow speed, and high ionization (charge states) of ions, to the hot, slowly moving plasmas in the outer magnetospheres of the giant planets, to the cold, corotating plasmas in inner magnetospheres. Space plasma instruments and techniques are reviewed, with an emphasis on hot plasma composition measurements. Starting with Faraday Cup detectors some 30 years ago, plasma instruments have evolved to the present time-of-flight systems with excellent mass resolution and three-dimensional viewing capabilities.

  19. Space flight operations communications phraseology and techniques

    NASA Technical Reports Server (NTRS)

    Noneman, S. R.

    1986-01-01

    Communications are a critical link in space flight operations. Specific communications phraseology and techniques have been developed to allow rapid and clear transfer of information. Communications will be clear and brief through the use of procedural words and phrases. Communications protocols standardize the required information transferred. The voicing of letters and numbers is discussed. The protocols used in air-to-ground communications are given. A glossary of communications terminology is presented in the appendix.

  20. Testing and Model Correlation of Sublimator Driven Coldplate Coupons

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik; Stephan, Ryan; Leimkuehler, Thomas O.

    2008-01-01

    The Sublimator Driven Coldplate (SDC) is a unique piece of thermal control hardware that has several advantages over a traditional thermal control scheme. The principal advantage is the possible elimination of a pumped fluid loop, potentially saving mass, power, and complexity. Because this concept relies on evaporative heat rejection techniques, it is primarily useful for short mission durations. Additionally, the concept requires a conductive path between the heat-generating component and the heat rejection device. Therefore, it is mostly a relevant solution for a vehicle with a relatively low heat rejection requirement. Coupon level tests were performed at NASA's Johnson Space Center to better understand the basic operational principles and to validate the analytical methods being used for the SDC development. This paper outlines the results of the SDC coupon tests, the subsequent thermal model correlation, and a description of the SDC Engineering Development Unit design.

  1. High performance techniques for space mission scheduling

    NASA Technical Reports Server (NTRS)

    Smith, Stephen F.

    1994-01-01

    In this paper, we summarize current research at Carnegie Mellon University aimed at development of high performance techniques and tools for space mission scheduling. Similar to prior research in opportunistic scheduling, our approach assumes the use of dynamic analysis of problem constraints as a basis for heuristic focusing of problem solving search. This methodology, however, is grounded in representational assumptions more akin to those adopted in recent temporal planning research, and in a problem solving framework which similarly emphasizes constraint posting in an explicitly maintained solution constraint network. These more general representational assumptions are necessitated by the predominance of state-dependent constraints in space mission planning domains, and the consequent need to integrate resource allocation and plan synthesis processes. First, we review the space mission problems we have considered to date and indicate the results obtained in these application domains. Next, we summarize recent work in constraint posting scheduling procedures, which offer the promise of better future solutions to this class of problems.

  2. Displacement, Substitution, Sublimation: A Bibliography.

    ERIC Educational Resources Information Center

    Pedrini, D. T.; Pedrini, Bonnie C.

    Sigmund Freund worked with the mechanisms of displacement, substitution, and sublimation. These mechanisms have many similarities and have been studied diagnostically and therapeutically. Displacement and substitution seem to fit in well with phobias, hysterias, somatiyations, prejudices, and scapegoating. Phobias, prejudices, and scapegoating…

  3. Eisenhower and the American Sublime

    ERIC Educational Resources Information Center

    O'Gorman, Ned

    2008-01-01

    This essay presents Dwight D. Eisenhower's presidential rhetoric as an iteration of an American synecdochal sublime. Eisenhower's rhetoric sought to re-aim civic sight beyond corporeal objects to the nation's transcendental essence. This rhetoric is intimately connected to prevailing political anxieties and exigencies, especially the problem of…

  4. Membrane evaporator/sublimator investigation

    NASA Technical Reports Server (NTRS)

    Elam, J.; Ruder, J.; Strumpf, H.

    1974-01-01

    Data are presented on a new evaporator/sublimator concept using a hollow fiber membrane unit with a high permeability to liquid water. The aim of the program was to obtain a more reliable, lightweight and simpler Extra Vehicular Life Support System (EVLSS) cooling concept than is currently being used.

  5. Matrix isolation sublimation: An apparatus for producing cryogenic beams of atoms and molecules

    SciTech Connect

    Sacramento, R. L.; Alves, B. X.; Silva, B. A.; Wolff, W.; Cesar, C. L.; Oliveira, A. N.; Li, M. S.

    2015-07-15

    We describe the apparatus to generate cryogenic beams of atoms and molecules based on matrix isolation sublimation. Isolation matrices of Ne and H{sub 2} are hosts for atomic and molecular species which are sublimated into vacuum at cryogenic temperatures. The resulting cryogenic beams are used for high-resolution laser spectroscopy. The technique also aims at loading atomic and molecular traps.

  6. Sublimating grains model of cometary coma.

    NASA Astrophysics Data System (ADS)

    Faggi, S.; Tozzi, G. P.; Brucato, J. R.

    Billion years of space weathering produces a crust of organic matter (see e.g. Kanuchova et al. 2012) that will be released when a comet enter for the first time in the inner Solar System. New comets, coming form the Oort Colud at their first passage close to the Sun, are particularly important because they are not differentiated by the Solar radiation and they are supposed to have a large quantity of ice organic matter close to the surface. When a comet approach to the Sun, its activity is driven by the sublimation of these nucleus ices: if the heliocentric distances, R_H , is greater than 3 AU the sublimation of CO and CO_2 ices is the main source of comet activity, otherwise at shorter distances, the sublimation of water become the most important mechanism of activity. These gases, escaping from the nucleus, drag in the coma grains that can be refractory dust (silicates, carbon), water ice and/or organic ices. Oort comets at their first passage in the inner Solar System, should produce an halo of organic or water icy particles. Our group has been monitoring new, inbound, bright Oort comets (C/2011 F1, C/2012 S1, C/2012 K1, C/2013 V5, C/2012 F3, C/2013 US10, C/2013 X1) to search for these icy grains. The method consists in detecting the cloud of sublimating grains in the inner coma by using the Sigma Af function (Tozzi et al. 2007) directly from images. However this over-population of grains, beside the sublimation, can be also due to short time activity (outburst) or too big grains expanding at very slow velocity, as it has been found in comet 67P/C-G (Tozzi eta al, 2011, A&A, 531, 54). To disentangle between the phenomena it is necessary to monitor the comet both at short timescale, for the outbursts (by repeating the observations after few nights), and at long term (weeks-months). If the cloud does not expand with the decreasing of the heliocentric distance there is high probability that we are in presence of organic and/or water ice grains. We can disentangle

  7. APPARATUS FOR CONDENSATION AND SUBLIMATION

    DOEpatents

    Schmidt, R.J.; Fuis, F. Jr.

    1958-10-01

    An apparatus is presented for the sublimation and condensation of uranium compounds in order to obtain an improved crystalline structure of this material. The apparatus comprises a vaporizing chamber and condensing structure connected thereto. There condenser is fitted with a removable liner having a demountable baffle attached to the liner by means of brackets and a removable pin. The baffle is of spiral cross-section and is provided with cooling coils disposed between the surfaces of the baffle for circulation of a temperature controlling liquid within the baffle. The cooling coll provides for controlllng the temperature of the baffle to insure formatlon of a satisfactory condensate, and the removable liner facilitates the removal of condensate formed during tbe sublimation process.

  8. AI Techniques for Space: The APSI Approach

    NASA Astrophysics Data System (ADS)

    Steel, R.; Niézette, M.; Cesta, A.; Verfaille, G., Lavagna, M.; Donati, A.

    2009-05-01

    This paper will outline the framework and tools developed under the Advanced Planning and Schedule Initiative (APSI) study performed by VEGA for the European Space Agency in collaboration with three academic institutions, ISTC-CNR, ONERA, and Politecnico di Milano. We will start by illustrating the background history to APSI and why it was needed, giving a brief summary of all the partners within the project and the rolls they played within it. We will then take a closer look at what APSI actually consists of, showing the techniques that were used and detailing the framework that was developed within the scope of the project. We will follow this with an elaboration on the three demonstration test scenarios that have been developed as part of the project, illustrating the re-use and synergies between the three cases along the way. We will finally conclude with a summary of some pros and cons of the approach devised during the project and outline future directions to be further investigated and expanded on within the context of the work performed within the project.

  9. Space optical navigation techniques: an overview

    NASA Astrophysics Data System (ADS)

    Rebordão, J. M.

    2013-11-01

    Optical or vision-based navigation is an enabling technology for satellite autonomous navigation associated to different navigation approaches such as cruising, fly-by, terrain relative navigation, landing, rendezvous and docking between spacecrafts, rigidity of multi-satellite constellations. Since 2001, in many different ESA projects, the author and his team (at INETI and currently at FCUL) have been associated to most of the developments of the optical components of autonomous navigation, in cooperation with space primes or GNC subsystems suppliers. A unique experience related to seemingly simple photonic concepts associated to computational vision, photonic noises, camera tradeoffs and system concepts has emerged, and deserves a synthesis especially because some of these concepts are being implemented in the ESA Proba 3 mission and ESA is currently updating the technology in view of forthcoming planetary missions to Jupiter, Jupiter moons and asteroids. It is important to note that the US have already flown several missions relying on autonomous navigation and that NASA experience is at least one decade old. System approaches, sources of difficulty, some tradeoffs in both (and between) hardware and software, critical interface issues between the imaging and GNC (Guidance, Navigation and Control) subsystems, image processing techniques, utilization of apriori or to be estimated information, uncertainties, simulation of the imaging chain and non-cooperative environments will be addressed synthetically for both passive (optical) and active (lidar) systems.

  10. Enthalpy of sublimation as measured using a silicon oscillator

    NASA Astrophysics Data System (ADS)

    Shakeel, Hamza; Pomeroy, J. M.

    In this study, we report the enthalpy of sublimation of common gases (nitrogen, oxygen, argon, carbon dioxide, neon, krypton, xenon, and water vapor) using a large area silicon oscillator with a sub-ng (~0.027 ng/cm2) mass sensitivity. The double paddle oscillator design enables high frequency stability (17 ppb) at cryogenic temperatures and provides a consistent technique for enthalpy measurements. The enthalpies of sublimation are derived from the rate of mass loss during programmed thermal desorption and are detected as a change in the resonance frequency of the self-tracking oscillator. These measured enthalpy values show excellent agreement with the accepted literature values.

  11. Sublimation rates of explosive materials : method development and initial results.

    SciTech Connect

    Phelan, James M.; Patton, Robert Thomas

    2004-08-01

    Vapor detection of explosives continues to be a technological basis for security applications. This study began experimental work to measure the chemical emanation rates of pure explosive materials as a basis for determining emanation rates of security threats containing explosives. Sublimation rates for TNT were determined with thermo gravimetric analysis using two different techniques. Data were compared with other literature values to provide sublimation rates from 25 to 70 C. The enthalpy of sublimation for the combined data was found to be 115 kJ/mol, which corresponds well with previously reported data from vapor pressure determinations. A simple Gaussian atmospheric dispersion model was used to estimate downrange concentrations based on continuous, steady-state conditions at 20, 45 and 62 C for a nominal exposed block of TNT under low wind conditions. Recommendations are made for extension of the experimental vapor emanation rate determinations and development of turbulent flow computational fluid dynamics based atmospheric dispersion estimates of standoff vapor concentrations.

  12. Space Simulation, 7th. [facilities and testing techniques

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Space simulation facilities and techniques are outlined that encompass thermal scale modeling, computerized simulations, reentry materials, spacecraft contamination, solar simulation, vacuum tests, and heat transfer studies.

  13. Cloud Computing Techniques for Space Mission Design

    NASA Technical Reports Server (NTRS)

    Arrieta, Juan; Senent, Juan

    2014-01-01

    The overarching objective of space mission design is to tackle complex problems producing better results, and faster. In developing the methods and tools to fulfill this objective, the user interacts with the different layers of a computing system.

  14. Direct Isolation of Purines and Pyrimidines from Nucleic Acids Using Sublimation

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Schubert, Michael; Bada, Jeffrey L.

    2003-01-01

    A sublimation technique was developed to isolate purines and pyrimidines directly from lambda-deoxyribonucleic acid (lambda-DNA) and Escherichia coli cells. The sublimation of adenine, cytosine, guanine, and thymine from lambda-DNA was tested under reduced pressure (approx. 0.5 Torr) at temperatures of >150 C. With the exception of guanine, approximately 60 -75% of each base was sublimed directly from the lambda-DNA and recovered on a coldfinger of the sublimation apparatus after heating to 450 C. Several nucleobases including adenine, cytosine, thymine, and uracil were also recovered from E. coli bacteria after heating the cells to the same temperature, although some thermal decomposition of the bases also occurred. These results demonstrate the feasibility of using sublimation to isolate purines and pyrimidines from native E. coli DNA and RNA without any chemical treatment of the cells.

  15. DBF technique for the space synchronization of bistatic (multistatic) radars

    NASA Astrophysics Data System (ADS)

    Zhao, Shujie; Geng, Fulu; Gao, Ruyun; Xie, Changrong; Ma, Xudong; Chen, Jianchun

    The space synchronization is one of the key techniques of bistatic(multistatic) radars. The concept and main parameters in implementing the space synchronization by pulse chasing with digital beam forming (DBF) technique are discussed. A implementation scheme as well as some of the test results of a prototype are also given in this paper.

  16. Future development in cryogenic techniques for space

    NASA Astrophysics Data System (ADS)

    Wanner, M.

    1992-12-01

    The detection of faint electromagnetic radiation in space astronomy and astrophysics requires very low temperatures to improve the signal to noise ratio of the very sensitive detectors in order to reduce the electronic noise of the detector amplifiers and finally to suppress the self emission of infrared radiation of the telescope itself. To provide such a cryogenic environment in space, both open and closed loop cooling systems using different cryogens are in use, thereby covering the whole temperature range from about 80K down to 1.8K. Future applications such as highly sensitive bolometers or SQUID's will ask for temperatures down to the subKelvin range. Such temperatures can be achieved by sophisticated low temperature cooling stages. Cryogenic cooling in space basically relies on the same cooling principles as in the laboratory. However the systems in general have to be specifically designed and new components have to be developed to match the cryogenic infrastructure to the specific demands of the optical instrument, the requirements from the satellite and the constraints imposed by the space environment.

  17. Investigations of the ionosphere by space techniques

    NASA Technical Reports Server (NTRS)

    Bowhill, S. A.

    1974-01-01

    Much of the impetus to ionosphere research since the International Geophysical Year has come from new types of measurement using space vehicles. The key developments are outlined, together with the contributions that they have made to the understanding of the ionosphere.

  18. Review of radiation hardening techniques for EDFAs in space environment

    NASA Astrophysics Data System (ADS)

    Wang, Qian; Tian, CuiPing; Wang, YingYing; Wang, Pu

    2015-03-01

    The damage mechanism and test technology of space radiation environment to space equipment was classified and the radiation protection demand of active fiber for space application was analyzed. The radiation hardening techniques of Ce doping, hydrogen loading and pre-radiation exposure and thermal annealing for Er:Yb co-doped fiber was surveyed.

  19. Robotic vision techniques for space operations

    NASA Technical Reports Server (NTRS)

    Krishen, Kumar

    1994-01-01

    Automation and robotics for space applications are being pursued for increased productivity, enhanced reliability, increased flexibility, higher safety, and for the automation of time-consuming tasks and those activities which are beyond the capacity of the crew. One of the key functional elements of an automated robotic system is sensing and perception. As the robotics era dawns in space, vision systems will be required to provide the key sensory data needed for multifaceted intelligent operations. In general, the three-dimensional scene/object description, along with location, orientation, and motion parameters will be needed. In space, the absence of diffused lighting due to a lack of atmosphere gives rise to: (a) high dynamic range (10(exp 8)) of scattered sunlight intensities, resulting in very high contrast between shadowed and specular portions of the scene; (b) intense specular reflections causing target/scene bloom; and (c) loss of portions of the image due to shadowing and presence of stars, Earth, Moon, and other space objects in the scene. In this work, developments for combating the adverse effects described earlier and for enhancing scene definition are discussed. Both active and passive sensors are used. The algorithm for selecting appropriate wavelength, polarization, look angle of vision sensors is based on environmental factors as well as the properties of the target/scene which are to be perceived. The environment is characterized on the basis of sunlight and other illumination incident on the target/scene and the temperature profiles estimated on the basis of the incident illumination. The unknown geometrical and physical parameters are then derived from the fusion of the active and passive microwave, infrared, laser, and optical data.

  20. Target space supersymmetric sigma model techniques

    SciTech Connect

    de Boer, Jan; Skenderis, Kostas

    1996-07-01

    We briefly review the covariant formulation of the Green-Schwarz superstring by Berkovits, and describe how a detailed tree-level and one-loop analysis of this model leads, for the first time, to a derivation of the low-energy effective action of the heterotic superstring while keeping target-space supersymmetry manifest. The resulting low-energy theory is old-minimal supergravity coupled to tensor multiplet. The dilaton is part of the compensator multiplet.

  1. Schopenhauer, Nietzsche, and the Aesthetically Sublime

    ERIC Educational Resources Information Center

    Vandenabeele, Bart

    2003-01-01

    Much has been written on the relationship between Arthur Schopenhauer and Friedrich Nietzsche. Much remains to be said, however, concerning their respective theories of the sublime. In this article, the author first argues against the traditional, dialectical view of Schopenhauer's theory of the sublime that stresses the crucial role the sublime…

  2. Cooling-Trough Condenser for Sublimation Tubes

    NASA Astrophysics Data System (ADS)

    Eisenbraun, E. J.; Lucas, J. M.

    1995-11-01

    A wrap-around, trough condenser for use with large diameter (2.5") sublimation tubes is described. The design permits attachment of the condenser to the sublimation tube without removing the tube from the heater. It also permits the use of a variety of liquid (tap water, Dry Ice, and alcohol or acetone) or solid (ice or Dry Ice) coolants.

  3. Tracking techniques for space shuttle rendezvous

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The space shuttle rendezvous radar has a requirement to track cooperative and non-cooperative targets. For this reason the Lunar Module (LM) Rendezvous Radar was modified to incorporate the capability of tracking a non-cooperative target. The modifications are discussed. All modifications except those relating to frequency diversity were completed, and system tests were performed to confirm proper performance in the non-cooperative mode. Frequency diversity was added to the radar and to the special test equipment, and then system tests were performed. This last set of tests included re-running the tests of the non-cooperative mode without frequency diversity, followed by tests with frequency diversity and tests of operation in the original cooperative mode.

  4. Space Shuttle MMOD Threat Mitigation Techniques

    NASA Technical Reports Server (NTRS)

    Hyde, J. L.; Christiansen, E. L.; Lear, D. M.; Kerr, J. H.

    2008-01-01

    Prior to each shuttle mission, threat assessments are performed to determine the risk of critical penetration, payload bay door radiator tube leak and crew module window replacement from Micrometeoroid and Orbital Debris (MMOD). Mission parameters, such as vehicle attitude, exposure time and altitude are used as inputs for the analysis. Ballistic limit equations, based on hypervelocity impact testing of shuttle materials are used to estimate the critical particle diameters of the outer surfaces of the vehicle. The assessments are performed using the BUMPER computer code at the NASA/JSC Hypervelocity Impact Technology Facility (HITF). The most critical involves the calculation of Loss of Crew and Vehicle (LOCV) risk. An overview of significant MMOD impacts on the Payload Bay Door radiators, wing leading edge reinforced carbon-carbon (RCC) panels and crew module windows will be presented, along with a discussion of the techniques NASA has implemented to reduce the risk from MMOD impacts. This paper will describe on-orbit inspection of the RCC regions and the methods used discern hypervelocity impact damage. Impact damage contingency plans and on-orbit repair techniques will also be discussed. The wing leading edge impact detection system (WLEIDS) and it s role in the reduction of on-orbit risk reduction will be presented. Finally, an analysis of alternative shuttle flight attitudes on MMOD risk will be demonstrated.

  5. Space Shuttle MMOD Threat Mitigation Techniques

    NASA Technical Reports Server (NTRS)

    Hyde, Justin L.; Christiansen, Eric L.; Kerr, James H.

    2007-01-01

    Prior to each shuttle mission, threat assessments are performed to determine the risk of critical penetration, payload bay door radiator tube leak and crew module window replacement from Micrometeoroid and Orbital Debris (MMOD). Mission parameters, such as vehicle attitude, exposure time and altitude are used as inputs for the analysis. Ballistic limit equations, based on hypervelocity impact testing of shuttle materials are used to estimate the critical particle diameters of the outer surfaces of the vehicle. The assessments are performed using the BUMPER computer code at the NASA/JSC Hypervelocity Impact Technology Facility (HITF). The most critical involves the calculation of Loss of Crew and Vehicle (LOCV) risk. In recent years, NASA has implemented several techniques to reduce the risk to the Shuttle from MMOD impacts. This paper will describe on-orbit inspection of the reinforced carbon-carbon (RCC) regions and the methods used discern hypervelocity impact damage. Impact damage contingency plans and on-orbit repair techniques will also be discussed. The wing leading edge impact detection system (WLEIDS) and it's role in the reduction of on-orbit risk reduction will be presented. Finally, an analysis of the effectivity of alternative shuttle flight attitudes on MMOD risk will be demonstrated.

  6. Trends and Techniques for Space Base Electronics

    NASA Technical Reports Server (NTRS)

    Trotter, J. D.; Wade, T. E.; Gassaway, J. D.

    1979-01-01

    Simulations of various phosphorus and boron diffusions in SOS were completed and a sputtering system, furnaces, and photolithography related equipment were set up. Double layer metal experiments initially utilized wet chemistry techniques. By incorporating ultrasonic etching of the vias, premetal cleaning a modified buffered HF, phosphorus doped vapox, and extended sintering, yields of 98% were obtained using the standard test pattern. A two dimensional modeling program was written for simulating short channel MOSFETs with nonuniform substrate doping. A key simplifying assumption used is that the majority carriers can be represented by a sheet charge at the silicon dioxide silicon interface. Although the program is incomplete, the two dimensional Poisson equation for the potential distribution was achieved. The status of other Z-D MOSFET simulation programs is summarized.

  7. Modeling techniques for gaining additional urban space

    NASA Astrophysics Data System (ADS)

    Thunig, Holger; Naumann, Simone; Siegmund, Alexander

    2009-09-01

    One of the major accompaniments of the globalization is the rapid growing of urban areas. Urban sprawl is the main environmental problem affecting those cities across different characteristics and continents. Various reasons for the increase in urban sprawl in the last 10 to 30 years have been proposed [1], and often depend on the socio-economic situation of cities. The quantitative reduction and the sustainable handling of land should be performed by inner urban development instead of expanding urban regions. Following the principal "spare the urban fringe, develop the inner suburbs first" requires differentiated tools allowing for quantitative and qualitative appraisals of current building potentials. Using spatial high resolution remote sensing data within an object-based approach enables the detection of potential areas while GIS-data provides information for the quantitative valuation. This paper presents techniques for modeling urban environment and opportunities of utilization of the retrieved information for urban planners and their special needs.

  8. Techniques for detumbling a disabled space base

    NASA Technical Reports Server (NTRS)

    Kaplan, M. H.

    1973-01-01

    Techniques and conceptual devices for carrying out detumbling operations are examined, and progress in the development of these concepts is discussed. Devices which reduce tumble to simple spin through active linear motion of a small mass are described, together with a Module for Automatic Dock and Detumble (MADD) that could perform an orbital transfer from the shuttle in order to track and dock at a preselected point on the distressed craft. Once docked, MADD could apply torques by firing thrustors to detumble the passive vehicle. Optimum combinations of mass-motion and external devices for various situation should be developed. The need for completely formulating the automatic control logic of MADD is also emphasized.

  9. Techniques for estimating Space Station aerodynamic characteristics

    NASA Technical Reports Server (NTRS)

    Thomas, Richard E.

    1993-01-01

    A method was devised and calculations were performed to determine the effects of reflected molecules on the aerodynamic force and moment coefficients for a body in free molecule flow. A procedure was developed for determining the velocity and temperature distributions of molecules reflected from a surface of arbitrary momentum and energy accommodation. A system of equations, based on momentum and energy balances for the surface, incident, and reflected molecules, was solved by a numerical optimization technique. The minimization of a 'cost' function, developed from the set of equations, resulted in the determination of the defining properties of the flow reflected from the arbitrary surface. The properties used to define both the incident and reflected flows were: average temperature of the molecules in the flow, angle of the flow with respect to a vector normal to the surface, and the molecular speed ratio. The properties of the reflected flow were used to calculate the contribution of multiply reflected molecules to the force and moments on a test body in the flow. The test configuration consisted of two flat plates joined along one edge at a right angle to each other. When force and moment coefficients of this 90 deg concave wedge were compared to results that did not include multiple reflections, it was found that multiple reflections could nearly double lift and drag coefficients, with nearly a 50 percent increase in pitching moment for cases with specular or nearly specular accommodation. The cases of diffuse or nearly diffuse accommodation often had minor reductions in axial and normal forces when multiple reflections were included. There were several cases of intermediate accommodation where the addition of multiple reflection effects more than tripled the lift coefficient over the convex technique.

  10. Offloading techniques for large deployable space structures

    NASA Technical Reports Server (NTRS)

    Caravaggio, Levino; Golob, Alex

    1992-01-01

    The validation and verification of large deployable space structures are continual challenges which face the integration and test engineer today. Spar Aerospace Limited has worked on various programs in which such structure validation was required and faces similar tasks in the future. This testing is reported and the different offloading and deployment methods which were used, as well as the proposed methods which will be used on future programs, are described. Past programs discussed include the Olympus solar array ambient and thermal vacuum deployments, and the Anik-E array and reflector deployments. The proposed MSAT reflector and boom ambient deployment tests, as well as the proposed RADARSAT Synthetic Aperture Radar (SAR) ambient and thermal vacuum deployment tests will also be presented. A series of tests relating to various component parts of the offloading equipment systems was required. These tests included the characterization and understanding of linear bearings and large (180 in-lbf) constant force spring motors in a thermal vacuum environment, and the results from these tests are presented.

  11. Comet 67P/CG: Influence of the sublimation coefficient on the temperature and outgassing

    NASA Astrophysics Data System (ADS)

    Kossacki, Konrad J.; Markiewicz, Wojciech J.

    2013-05-01

    The sublimation rate of ice is commonly calculated using simple Hertz-Knudsen formula. This formula is derived from the kinetic theory of gases and ignores microphysical processes determining the actual sublimation rate. The microphysical processes can be accounted for by including in the Herz-Knudsen equation a temperature dependent sublimation coefficient (Kossacki, K.J., Markiewicz, W.J., Skorov, Y., Koemle, N.I. [1999]. Planet. Space Sci. 47, 1521-1530; Gundlach, B., Skorov, Y.V., Blum, J. [2011]. Icarus, 213, 710-719). Here we address the question to what extent inaccuracy of the simple Hertz-Knudsen equation affects the calculated temperature of a cometary nucleus and the emission rate of water vapor to space. We performed numerical simulations dealing with evolution of a model comet of the orbit the same as Comet 67P/Churyumov-Gerasimenko, target comet of the Rosetta mission (Glassmeier, K.H., Boehnardt, H., Koshny, D., Kuhrt, E., Richter, I. [2007]. Space Sci. Rev. 128, 1-21). We have found, that the temperature below dust mantle is most sensitive to the value of the sublimation coefficient when the mantle is coarse grained, while the sublimation rate is most affected when the mantle is fine grained. We also conclude that derivation of the temperature below the mantle from the measured water production rate ignoring temperature dependence of the sublimation coefficient leads to an underestimate of the temperature by more than 10 K when the nucleus is fine grained.

  12. Gravimetry and Space Techniques Applied to Geodynamics and Ocean Dynamics

    NASA Astrophysics Data System (ADS)

    Schutz, Bob E.; Anderson, Allen; Froidevaux, Claude; Parke, Michael

    The variety of disciplines represented in this volume (including space geodesy, oceanography, geophysics, and celestial mechanics) attest to the interdisciplinary applications of gravimetry and space techniques. The relation to sea level is addressed within some of the papers and the contributions of the techniques to development of global gravity models are discussed. The space technique of satellite altimetry has become a prominent contributor to sea surface topography as well as ocean tide models and determination of gravity, especially in ocean areas. Ocean tides influence the motion of near-Earth satellites and the rotation of the Earth. Modern space geodesy is increasingly relying on the Global Positioning System for measuring geophysical phenomena manifested at the surface through crustal deformations. Furthermore, the geophysical interpretation of gravity anomalies has been facilitated by the introduction of modern techniques. This volume represents only a small "snapshot" of the interdisciplinary research being conducted. Modem space geodesy is one of the common links between the disciplines reflected in this volume. New developments in gravimetry and space techniques will further enhance and foster interdisciplinary work in coming years.

  13. Ischiofemoral Space Decompression Through Posterolateral Approach: Cutting Block Technique

    PubMed Central

    Howse, Elizabeth A.; Mannava, Sandeep; Tamam, Cüneyt; Martin, Hal D.; Bredella, Miriam A.; Stubbs, Allston J.

    2014-01-01

    Ischiofemoral space impingement has become an increasingly recognized extracapsular cause of atypical hip, deep gluteal, and groin pain that can be treated endoscopically. We present a minimally invasive posterolateral technique that preserves the attachment of the iliopsoas tendon and quadratus femoris insertion while decompressing the ischiofemoral space by resecting the lesser trochanter. Furthermore, we present tips to perform this technique in a manner that minimizes the potential for damage to the sciatic nerve. This technique also allows the surgeon to treat concurrent hip pathology arthroscopically. PMID:25685670

  14. Sublimation in bright spots on (1) Ceres

    NASA Astrophysics Data System (ADS)

    Nathues, A.; Hoffmann, M.; Schaefer, M.; Le Corre, L.; Reddy, V.; Platz, T.; Cloutis, E. A.; Christensen, U.; Kneissl, T.; Li, J.-Y.; Mengel, K.; Schmedemann, N.; Schaefer, T.; Russell, C. T.; Applin, D. M.; Buczkowski, D. L.; Izawa, M. R. M.; Keller, H. U.; O'Brien, D. P.; Pieters, C. M.; Raymond, C. A.; Ripken, J.; Schenk, P. M.; Schmidt, B. E.; Sierks, H.; Sykes, M. V.; Thangjam, G. S.; Vincent, J.-B.

    2015-12-01

    The dwarf planet (1) Ceres, the largest object in the main asteroid belt with a mean diameter of about 950 kilometres, is located at a mean distance from the Sun of about 2.8 astronomical units (one astronomical unit is the Earth-Sun distance). Thermal evolution models suggest that it is a differentiated body with potential geological activity. Unlike on the icy satellites of Jupiter and Saturn, where tidal forces are responsible for spewing briny water into space, no tidal forces are acting on Ceres. In the absence of such forces, most objects in the main asteroid belt are expected to be geologically inert. The recent discovery of water vapour absorption near Ceres and previous detection of bound water and OH near and on Ceres (refs 5, 6, 7) have raised interest in the possible presence of surface ice. Here we report the presence of localized bright areas on Ceres from an orbiting imager. These unusual areas are consistent with hydrated magnesium sulfates mixed with dark background material, although other compositions are possible. Of particular interest is a bright pit on the floor of crater Occator that exhibits probable sublimation of water ice, producing haze clouds inside the crater that appear and disappear with a diurnal rhythm. Slow-moving condensed-ice or dust particles may explain this haze. We conclude that Ceres must have accreted material from beyond the ‘snow line’, which is the distance from the Sun at which water molecules condense.

  15. Sublimation in bright spots on (1) Ceres.

    PubMed

    Nathues, A; Hoffmann, M; Schaefer, M; Le Corre, L; Reddy, V; Platz, T; Cloutis, E A; Christensen, U; Kneissl, T; Li, J-Y; Mengel, K; Schmedemann, N; Schaefer, T; Russell, C T; Applin, D M; Buczkowski, D L; Izawa, M R M; Keller, H U; O'Brien, D P; Pieters, C M; Raymond, C A; Ripken, J; Schenk, P M; Schmidt, B E; Sierks, H; Sykes, M V; Thangjam, G S; Vincent, J-B

    2015-12-10

    The dwarf planet (1) Ceres, the largest object in the main asteroid belt with a mean diameter of about 950 kilometres, is located at a mean distance from the Sun of about 2.8 astronomical units (one astronomical unit is the Earth-Sun distance). Thermal evolution models suggest that it is a differentiated body with potential geological activity. Unlike on the icy satellites of Jupiter and Saturn, where tidal forces are responsible for spewing briny water into space, no tidal forces are acting on Ceres. In the absence of such forces, most objects in the main asteroid belt are expected to be geologically inert. The recent discovery of water vapour absorption near Ceres and previous detection of bound water and OH near and on Ceres (refs 5-7) have raised interest in the possible presence of surface ice. Here we report the presence of localized bright areas on Ceres from an orbiting imager. These unusual areas are consistent with hydrated magnesium sulfates mixed with dark background material, although other compositions are possible. Of particular interest is a bright pit on the floor of crater Occator that exhibits probable sublimation of water ice, producing haze clouds inside the crater that appear and disappear with a diurnal rhythm. Slow-moving condensed-ice or dust particles may explain this haze. We conclude that Ceres must have accreted material from beyond the 'snow line', which is the distance from the Sun at which water molecules condense. PMID:26659183

  16. Carbon-Sublimation Production of Fullerenes.

    NASA Astrophysics Data System (ADS)

    Tinker, Frank Albert

    1995-01-01

    Carbon-sublimation production of fullerenes enjoys wide use in both experimental and industrial application worldwide. Although it has been nearly five years since the inception of the technique, little is known about the roles various parameters play in the production process. This work attempts to shed light, both experimentally and theoretically, on the basic processes at work in this type of fullerene production. Experimental results herein show that a functional relationship exists among the C_{60 }, C_{70}, C_{76}, C_ {78}, and C_{84} fullerenes produced in carbon arcs. This result is interpreted to mean that an equilibrium description of the production process may be valid. Theoretical calculations are then offered in support of such a view. The theory goes on to show details of an equilibrium description that reproduce essential features of fullerene mass-spectra. It is shown that equilibrium abundances of n-atom -sized clusters are highly dependent on the stoichiometric equation chosen to describe the system. However, common traits of the investigated equilibrium descriptions lead to useful conclusions.

  17. A grid spacing control technique for algebraic grid generation methods

    NASA Technical Reports Server (NTRS)

    Smith, R. E.; Kudlinski, R. A.; Everton, E. L.

    1982-01-01

    A technique which controls the spacing of grid points in algebraically defined coordinate transformations is described. The technique is based on the generation of control functions which map a uniformly distributed computational grid onto parametric variables defining the physical grid. The control functions are smoothed cubic splines. Sets of control points are input for each coordinate directions to outline the control functions. Smoothed cubic spline functions are then generated to approximate the input data. The technique works best in an interactive graphics environment where control inputs and grid displays are nearly instantaneous. The technique is illustrated with the two-boundary grid generation algorithm.

  18. Error control techniques for satellite and space communications

    NASA Technical Reports Server (NTRS)

    Costello, Daniel J., Jr.

    1991-01-01

    Research activities related to error control techniques for satellite and space communication are reported. Specific areas of research include: coding gains for bandwidth efficient codes, hardware implementation of a bandwidth efficient coding scheme for the Hubble Space Telescope, construction of long trellis codes for use with sequential decoding, performance analysis of multilevel trellis codes, and M-algorithm decoding of trellis codes. Each topic is discussed in a corresponding paper that appears in the appendices.

  19. The Advanced Space Plant Culture Device with Live Imaging Technique

    NASA Astrophysics Data System (ADS)

    Zheng, Weibo; Zhang, Tao; Tong, Guanghui

    The live imaging techniques, including the color and fluorescent imags, are very important and useful for space life science. The advanced space plant culture Device (ASPCD) with live imaging Technique, developed for Chinese Spacecraft, would be introduced in this paper. The ASPCD had two plant experimental chambers. Three cameras (two color cameras and one fluorescent camera) were installed in the two chambers. The fluorescent camera could observe flowering genes, which were labeled by GFP. The lighting, nutrient, temperature controling and water recycling were all independent in each chamber. The ASPCD would beed applied to investigate for the growth and development of the high plant under microgravity conditions on board the Chinese Spacecraft.

  20. Testing and Model Correlation of Sublimator Driven Coldplate Coupons and EDU

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.

    2009-01-01

    The Sublimator Driven Coldplate (SDC) is a unique piece of thermal control hardware that has several advantages over a more traditional thermal control system. The principal advantage is the possible elimination of a pumped fluid loop, potentially saving mass, power, and complexity. Because this concept relies on evaporative heat rejection techniques, it is primarily useful for short mission durations. Additionally, the concept requires a conductive path between the heat-generating component and the heat rejection device. Therefore, it is mostly a relevant solution for a vehicle with a relatively low heat rejection requirement and/or short transport distances. Tests were performed on coupons and an Engineering Development Unit (EDU) at NASA s Johnson Space Center to better understand the basic operational principles and to validate the analytical methods being used for the SDC development. This paper outlines the results of the SDC tests, the subsequent thermal model correlation, and a description of the SDC Engineering Development Unit test results.

  1. Near-equilibrium growth of thick, high quality beta-SiC by sublimation

    NASA Technical Reports Server (NTRS)

    Shields, Virgil B.; Fekade, Konjit; Spencer, Michael G.

    1993-01-01

    A close spaced near-equilibrium growth technique was used to produce thick, high quality epitaxial layers of beta-silicon carbide. The process utilized a sublimation method to grow morphologically smooth layers. The beta silicon carbide growth layers varied from about 200 to 750 microns in thickness. Chemical vapor deposition grown, 2-10 microns, beta silicon carbide films were used as seeds at 1860 and 1910 C growth temperatures. The respective average growth rates were 20 and 30 microns per hour. The layers are p-type with a 3.1 x 10 exp 17/cu cm carrier concentration. Electrical measurements indicate considerable improvement in the breakdown voltage of Schottky barriers on growth samples. Breakdown values ranged from 25 to 60 V. These measurements represent the highest values reported for 3C-SiC.

  2. Preventing Technique of Metal Deposition on Optical Devices in Space Diode Laser Welding for Space Applications

    NASA Astrophysics Data System (ADS)

    Suita, Yoshikazu; Tanaka, Kenji; Ohtani, Masato; Shobako, Shinichiro; Terajima, Noboru; Hiraoka, Nobuaki

    In future space developments, the welding in space may be required for the repairs of the ISS and the constructions of lunar base and space structures. The authors have studied the space Gas Hollow Tungsten Arc (GHTA) welding process since 1993. This paper describes the results for space applying the space Diode Laser (DL) welding process which the authors proposed in 2002. It is necessary to prevent the metal deposition on optical devices in order to utilize the space DL welding process in space. The authors studied the preventing technique of metal deposition which covered optical devices with the nozzle and blew the shielding gas out from nozzle outlet. The metal deposition can be reduced by supplying the nozzle with inert gas and blowing the gas out from nozzle outlet. The shielding gas argon perfectly prevents the metal deposition on optical devices when argon pressurizes the nozzle to over 19.9 Pa and spouts out from the nozzle outlet.

  3. Applications notice. [application of space techniques to earth resources, environment management, and space processing

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The discipline programs of the Space and Terrestrial (S&T) Applications Program are described and examples of research areas of current interest are given. Application of space techniques to improve conditions on earth are summarized. Discipline programs discussed include: resource observations; environmental observations; communications; materials processing in space; and applications systems/information systems. Format information on submission of unsolicited proposals for research related to the S&T Applications Program are given.

  4. An Overview of the Life Space Interview Technique.

    ERIC Educational Resources Information Center

    Gardner, Peter J.

    The life space interview, in which a teacher (or other important member of the child's world) interacts with a student in terms of the student's direct life experience in order to set boundaries and appropriate actions, is an effective technique for structured interaction with adolescents with severe behavior disorders. In order to facilitate the…

  5. THE NEEDS OF EDUCATION FOR UTILIZATION OF SPACE TRANSMISSION TECHNIQUES.

    ERIC Educational Resources Information Center

    BRONSON, VERNON; AND OTHERS

    STUDIES AND CONFERENCES WERE HELD ON NEEDS OF EDUCATION FOR THE UTILIZATION OF SATELLITE TV TRANSMISSION TECHNIQUES, TO DETERMINE THE ROLE WHICH EDUCATION MIGHT PLAY IN DEVELOPMENT AND TO PREDICT FUTURE NEEDS. RESULTS OF THESE STUDIES AND CONFERENCES HAVE BEEN REPORTED FOR AN ORGANIZED LOOK AT THE DEVELOPMENT OF SPACE COMMUNICATION, ITS…

  6. Experimental determination of ice sublimation energies

    NASA Astrophysics Data System (ADS)

    Luna, R.; Canto, J.; Satorre, M. A.; Domingo, M.

    2011-11-01

    In Astrophysics, the study of ices is important due to the wide range of scenarios in which they are present. Their physical and chemical characteristics play an important role in the study of the interstellar medium (ISM). The assessment of the energy of sublimation allows us to improve our understanding of physical and/or chemical processes that take place where ices are present. The energy of sublimation E_sub is defined as the change of energy between solid and gas phase of certain molecule. This value is important to determinate other thermodynamical parameters such as the reticular energy of ionic compounds, the energy of formation in gas phase from the energy of formation in condensed phase, or to estimate the sublimation rate, which is very important in determining the evolution of surfaces of astrophysical objects.

  7. A New Method for Estimating Bacterial Abundances in Natural Samples using Sublimation

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Cleaves, H. James; Schubert, Michael; Aubrey, Andrew; Bada, Jeffrey L.

    2004-01-01

    We have developed a new method based on the sublimation of adenine from Escherichia coli to estimate bacterial cell counts in natural samples. To demonstrate this technique, several types of natural samples including beach sand, seawater, deep-sea sediment, and two soil samples from the Atacama Desert were heated to a temperature of 500 C for several seconds under reduced pressure. The sublimate was collected on a cold finger and the amount of adenine released from the samples then determined by high performance liquid chromatography (HPLC) with UV absorbance detection. Based on the total amount of adenine recovered from DNA and RNA in these samples, we estimated bacterial cell counts ranging from approx. l0(exp 5) to l0(exp 9) E. coli cell equivalents per gram. For most of these samples, the sublimation based cell counts were in agreement with total bacterial counts obtained by traditional DAPI staining. The simplicity and robustness of the sublimation technique compared to the DAPI staining method makes this approach particularly attractive for use by spacecraft instrumentation. NASA is currently planning to send a lander to Mars in 2009 in order to assess whether or not organic compounds, especially those that might be associated with life, are present in Martian surface samples. Based on our analyses of the Atacama Desert soil samples, several million bacterial cells per gam of Martian soil should be detectable using this sublimation technique.

  8. Heat transfer enhancement techniques for Space Station cold plates

    NASA Astrophysics Data System (ADS)

    Peterson, G. P.; Fletcher, L. S.

    1990-01-01

    Two attachment techniques for mounting electronic equipment to Space Station cold plates were analyzed and compared using thin foils of lead, tin, aluminum, and copper to enhance the thermal contact conductance. The two techniques evaluated included a 70 mm x 70 mm bolted attachment technique and an attachment scheme using an inflatable bladder. The results indicate that, even in the presence of the metallic foils, the bolted technique results in large variations in the local thermal contact conductance over the surface of the cold plate, while the pressurized bladder yields more uniform local contact conductance values. In addition, the results indicated that the lead foil provided an enhancement factor of approximately 3, the tin foil an enhancement factor of approximately 1.5, the aluminum an enhancement factor of approximately 1.0, and the copper an enhancement factor of approximately 0.9.

  9. Data Compression Techniques for Advanced Space Transportation Systems

    NASA Technical Reports Server (NTRS)

    Bradley, William G.

    1998-01-01

    Advanced space transportation systems, including vehicle state of health systems, will produce large amounts of data which must be stored on board the vehicle and or transmitted to the ground and stored. The cost of storage or transmission of the data could be reduced if the number of bits required to represent the data is reduced by the use of data compression techniques. Most of the work done in this study was rather generic and could apply to many data compression systems, but the first application area to be considered was launch vehicle state of health telemetry systems. Both lossless and lossy compression techniques were considered in this study.

  10. Improved Space Surveillance Network (SSN) Scheduling using Artificial Intelligence Techniques

    NASA Astrophysics Data System (ADS)

    Stottler, D.

    There are close to 20,000 cataloged manmade objects in space, the large majority of which are not active, functioning satellites. These are tracked by phased array and mechanical radars and ground and space-based optical telescopes, collectively known as the Space Surveillance Network (SSN). A better SSN schedule of observations could, using exactly the same legacy sensor resources, improve space catalog accuracy through more complementary tracking, provide better responsiveness to real-time changes, better track small debris in low earth orbit (LEO) through efficient use of applicable sensors, efficiently track deep space (DS) frequent revisit objects, handle increased numbers of objects and new types of sensors, and take advantage of future improved communication and control to globally optimize the SSN schedule. We have developed a scheduling algorithm that takes as input the space catalog and the associated covariance matrices and produces a globally optimized schedule for each sensor site as to what objects to observe and when. This algorithm is able to schedule more observations with the same sensor resources and have those observations be more complementary, in terms of the precision with which each orbit metric is known, to produce a satellite observation schedule that, when executed, minimizes the covariances across the entire space object catalog. If used operationally, the results would be significantly increased accuracy of the space catalog with fewer lost objects with the same set of sensor resources. This approach inherently can also trade-off fewer high priority tasks against more lower-priority tasks, when there is benefit in doing so. Currently the project has completed a prototyping and feasibility study, using open source data on the SSN's sensors, that showed significant reduction in orbit metric covariances. The algorithm techniques and results will be discussed along with future directions for the research.

  11. Heat of Sublimation of I-2.

    ERIC Educational Resources Information Center

    Henderson, Giles; Robarts, Ronald A., Jr.

    1978-01-01

    Describes an inexpensive double-beam laser photometry experiment to determine the molar heat of sublimation of I-2. The experiment employs common laboratory materials and components and gives results with a two percent to three percent accuracy. (Author/GA)

  12. Energy dissipation during sublimation from porous media

    NASA Astrophysics Data System (ADS)

    Keller, H. U.; Skorov, Yu. V.

    2002-09-01

    Several physical processes during the sublimation from and inside porous media have been investigated in detail in a series our papers (Skorov et al., 1999, Icarus 140, 173, Skorov et al., 2001, Icarus 153, 180, Davidsson and Skorov, 2002, Icarus 156, 223, Davidsson and Skorov, 2002, Icarus, in press) in order to analyse the gas production of cometary nuclei . New features are the absorption of the irradiation within the uppermost layers of the pores (rather than on the surface), taking into account the gas pressure of the coma, and temperature dependent condensation and sublimation coefficients. Detailed kinetic calculations revealed deviations from the canonical gasdynamic models. We will summarize the impact of these new calculations on the physics of sublimation from a cometary nucleus. The absorption of the irradiation below the surface leads to a decrease of sublimation flux near the subsolar point but to an increase near the evening terminator and nightside of a rotating nucleus. More absorbed energy is available to be transferred into the interior of the nucleus. This effect and consequences for the development of cometary nuclei will be discussed.

  13. No reduction using sublimation of cyanuric acid

    DOEpatents

    Perry, Robert A.

    1990-01-01

    An arrangement for reducing the NO content of a gas stream comprises contacting the gas stream with NHCO into a temperature effective for heat induced decomposition of HNCO and for resultant lowering of the NO content of the gas stream. Preferably, the HNCO is generated by sublimation of cyanuric acid.

  14. NO reduction using sublimation of cyanuric acid

    DOEpatents

    Perry, Robert A.

    1988-01-01

    An arrangement for reducing the NO content of a gas stream comprises contacting the gas stream with HNCO at a temperature effective for heat induced decomposition of HNCO and for resultant lowering of the NO content of the gas stream. Preferably, the HNCO is generated by sublimation of cyanuric acid.

  15. Space geodetic techniques for global modeling of ionospheric peak parameters

    NASA Astrophysics Data System (ADS)

    Alizadeh, M. Mahdi; Schuh, Harald; Schmidt, Michael

    The rapid development of new technological systems for navigation, telecommunication, and space missions which transmit signals through the Earth’s upper atmosphere - the ionosphere - makes the necessity of precise, reliable and near real-time models of the ionospheric parameters more crucial. In the last decades space geodetic techniques have turned into a capable tool for measuring ionospheric parameters in terms of Total Electron Content (TEC) or the electron density. Among these systems, the current space geodetic techniques, such as Global Navigation Satellite Systems (GNSS), Low Earth Orbiting (LEO) satellites, satellite altimetry missions, and others have found several applications in a broad range of commercial and scientific fields. This paper aims at the development of a three-dimensional integrated model of the ionosphere, by using various space geodetic techniques and applying a combination procedure for computation of the global model of electron density. In order to model ionosphere in 3D, electron density is represented as a function of maximum electron density (NmF2), and its corresponding height (hmF2). NmF2 and hmF2 are then modeled in longitude, latitude, and height using two sets of spherical harmonic expansions with degree and order 15. To perform the estimation, GNSS input data are simulated in such a way that the true position of the satellites are detected and used, but the STEC values are obtained through a simulation procedure, using the IGS VTEC maps. After simulating the input data, the a priori values required for the estimation procedure are calculated using the IRI-2012 model and also by applying the ray-tracing technique. The estimated results are compared with F2-peak parameters derived from the IRI model to assess the least-square estimation procedure and moreover, to validate the developed maps, the results are compared with the raw F2-peak parameters derived from the Formosat-3/Cosmic data.

  16. Mathematical analysis techniques for modeling the space network activities

    NASA Technical Reports Server (NTRS)

    Foster, Lisa M.

    1992-01-01

    The objective of the present work was to explore and identify mathematical analysis techniques, and in particular, the use of linear programming. This topic was then applied to the Tracking and Data Relay Satellite System (TDRSS) in order to understand the space network better. Finally, a small scale version of the system was modeled, variables were identified, data was gathered, and comparisons were made between actual and theoretical data.

  17. Active vibration control techniques for flexible space structures

    NASA Technical Reports Server (NTRS)

    Parlos, Alexander G.; Jayasuriya, Suhada

    1990-01-01

    Two proposed control system design techniques for active vibration control in flexible space structures are detailed. Control issues relevant only to flexible-body dynamics are addressed, whereas no attempt was made to integrate the flexible and rigid-body spacecraft dynamics. Both of the proposed approaches revealed encouraging results; however, further investigation of the interaction of the flexible and rigid-body dynamics is warranted.

  18. Heuristic Techniques Application In A 3-D Space

    NASA Astrophysics Data System (ADS)

    Mazouz, A. Kader

    1989-02-01

    This paper discusses the application of a heuristic technique to stack regular and irregular shapes objects on the same container or on the same pallet. The computer representation of any object is based on the recursive octree method where each unit volume element is a voxel. Then, the choice of the space taken by any shape object within the volume is made through the heuristic approach. The heuristic technique developed is an evaluation function that compares all the available spaces based on weighing factors and threshold levels. The parameters used are shape, space available, contents of the object, and dimensions. The goal is to choose the most feasible available space every time an object is ready to be stacked. The heuristic algorithm is implemented within a knowledge based system to control a flexible material handling cell. Generally the cell comprises a material handling robot, a conveyance system that brings the objects to the cell where objects are distributed randomly to the cell, a vision system to identify the objects and verify the stacking procedure, and a computer to control and initiate the decision making process to stack all shape objects on the same volume.

  19. Exploration Challenges: Transferring Ground Repair Techniques to Space Flight Application

    NASA Technical Reports Server (NTRS)

    McLemore, Carole A.; Kennedy, James P.; Rose, Frederick A.; Evans, Brian W.

    2007-01-01

    Fulfilling NASA's Vision for Space Exploration will demand an extended presence in space at distances from our home planet that exceed our current experience in space logistics and maintenance. The ability to perform repairs in lieu of the customary Orbital Replacement Unit (ORU) process where a faulty part is replaced will be elevated from contingency to routine to sustain operations. The use and cost effectiveness of field repairs for ground based operations in industry and the military have advanced with the development of technology in new materials, new repair techniques and new equipment. The unique environments, accessibility constraints and Extra Vehicular Activity (EVA) issues of space operations will require extensive assessment and evolution of these technologies to provide an equivalent and expected level of assurance to mission success. Challenges include the necessity of changes in design philosophy and policy, extremes in thermal cycling, disruptive forces (such as static charge and wind entrainment) on developed methods for control of materials, dramatically increased volatility of chemicals for cleaning and other compounds due to extremely low pressures, the limits imposed on dexterity and maneuverability by current EVA equipment and practices, and the necessity of unique verification methodology. This paper describes these challenges in and discusses the effects on the established ground techniques for repair. The paper also describes the leading repair methodology candidates and their beneficial attributes for resolving these issues with the evolution of technology.

  20. Multi-technique combination of space geodesy observations

    NASA Astrophysics Data System (ADS)

    Zoulida, Myriam; Pollet, Arnaud; Coulot, David; Biancale, Richard; Rebischung, Paul; Collilieux, Xavier

    2014-05-01

    Over the last few years, combination at the observation level (COL) of the different space geodesy techniques has been thoroughly studied. Various studies have shown that this type of combination can take advantage of common parameters. Some of these parameters, such as Zenithal Tropospheric Delays (ZTD), are available on co-location sites, where more than one technique is present. Local ties (LT) are provided for these sites, and act as intra-technique links and allow resulting terrestrial reference frames (TRF) to be homogeneous. However the use of LT can be problematic on weekly calculations, where their geographical distribution can be poor, and there are often differences observed between available LTs and space geodesy results. Similar co-locations can be found on multi-technique satellites, where more than one technique receiver is featured. A great advantage of these space ties (STs) is the densification of co-locations as the orbiting satellite acts as a moving station. The challenge of using space ties relies in the accurate knowledge or estimation of their values, as officially provided values are sometimes not reaching the required level of precision for the solution, due to receivers' or acting forces mismodelings and other factors. Thus, the necessity of an estimation and/or weighting strategy for the STs is introduced. To this day, on subsets of available data, using STs has shown promising results regarding the TRF determination through the stations' positions estimation, on the orbit determination of the GPS constellation and on the GPS antenna Phase Center Offsets and Variations (PCO and PCV) . In this study, results from a multi-technique combination including the Jason-2 satellite and its effect on the GNSS orbit determination during the CONT2011 period are presented, as well as some preliminary results on station positions' determination. Comparing resulting orbits with official solutions provides an assessment of the effect on the orbit

  1. System and method for suppressing sublimation using opacified aerogel

    NASA Technical Reports Server (NTRS)

    Sakamoto, Jeff S. (Inventor); Snyder, G. Jeffrey (Inventor); Calliat, Thierry (Inventor); Fleurial, Jean-Pierre (Inventor); Jones, Steven M. (Inventor); Palk, Jong-Ah (Inventor)

    2008-01-01

    The present invention relates to a castable, aerogel-based, ultra-low thermal conductivity opacified insulation to suppress sublimation. More specifically, the present invention relates to an aerogel opacified with various opacifying or reflecting constituents to suppress sublimation and provide thermal insulation in thermoelectric modules. The opacifying constituent can be graded within the aerogel for increased sublimation suppression, and the density of the aerogel can similarly be graded to achieve optimal thermal insulation and sublimation suppression.

  2. Phase Space Tomography: A Simple, Portable and Accurate Technique to Map Phase Spaces of Beams with Space Charge

    SciTech Connect

    Stratakis, D.; Kishek, R. A.; Bernal, S.; Walter, M.; Haber, I.; Fiorito, R.; Thangaraj, J. C. T.; Quinn, B.; Reiser, M.; O'Shea, P. G.; Li, H.

    2006-11-27

    In order to understand the charged particle dynamics, e.g. the halo formation, emittance growth, x-y energy transfer and coupling, knowledge of the actual phase space is needed. Other the past decade there is an increasing number of articles who use tomography to map the beam phase space and measure the beam emittance. These studies where performed at high energy facilities where the effect of space charge was neglible and therefore not considered in the analysis. This work extends the tomography technique to beams with space charge. In order to simplify the analysis linear forces where assumed. By carefully modeling the tomography process using the particle-in-cell code WARP we test the validity of our assumptions and the accuracy of the reconstructed phase space. Finally, we report experimental results of phase space mapping at the University of Maryland Electron Ring (UMER) using tomography.

  3. Methods and Techniques for Risk Prediction of Space Shuttle Upgrades

    NASA Technical Reports Server (NTRS)

    Hoffman, Chad R.; Pugh, Rich; Safie, Fayssal

    1998-01-01

    Since the Space Shuttle Accident in 1986, NASA has been trying to incorporate probabilistic risk assessment (PRA) in decisions concerning the Space Shuttle and other NASA projects. One major study NASA is currently conducting is in the PRA area in establishing an overall risk model for the Space Shuttle System. The model is intended to provide a tool to predict the Shuttle risk and to perform sensitivity analyses and trade studies including evaluation of upgrades. Marshall Space Flight Center (MSFC) and its prime contractors including Pratt and Whitney (P&W) are part of the NASA team conducting the PRA study. MSFC responsibility involves modeling the External Tank (ET), the Solid Rocket Booster (SRB), the Reusable Solid Rocket Motor (RSRM), and the Space Shuttle Main Engine (SSME). A major challenge that faced the PRA team is modeling the shuttle upgrades. This mainly includes the P&W High Pressure Fuel Turbopump (HPFTP) and the High Pressure Oxidizer Turbopump (HPOTP). The purpose of this paper is to discuss the various methods and techniques used for predicting the risk of the P&W redesigned HPFTP and HPOTP.

  4. Surveying co-located space geodesy techniques for ITRF computation

    NASA Astrophysics Data System (ADS)

    Sarti, P.; Sillard, P.; Vittuari, L.

    2003-04-01

    We present a comprehensive operational methodology, based on classical geodesy triangulation and trilateration, that allows the determination of reference points of the five space geodesy techniques used in ITRF computation (i.e.: DORIS, GPS, LLR, SLR, VLBI). Most of the times, for a single technique, the reference point is not accessible and measurable directly. Likewise, no mechanically determined ex-center with respect to an external and measurable point is usually given. In these cases, it is not possible to directly measure the sought reference points and it is even less straightforward to obtain the statistical information relating these points for different techniques. We outline the most general practical surveying methodology that permits to recover the reference points of the different techniques regardless of their physical materialization. We also give a detailed analytical approach for less straightforward cases (e.g.: non geodetic VLBI antennae and SLR/LLR systems). We stress the importance of surveying instrumentation and procedure in achieving the best possible results and outline the impact of the information retrieved with our method in ITRF computation. In particular, we will give numerical examples of computation of the reference point of VLBI antennae (Ny Aalesund and Medicina) and the ex-centre vector computation linking co-located VLBI and GPS techniques in Medicina (Italy). A special attention was paid to the rigorous derivation of statistical elements. They will be presented in an other presentation.

  5. Multiclass Bayes error estimation by a feature space sampling technique

    NASA Technical Reports Server (NTRS)

    Mobasseri, B. G.; Mcgillem, C. D.

    1979-01-01

    A general Gaussian M-class N-feature classification problem is defined. An algorithm is developed that requires the class statistics as its only input and computes the minimum probability of error through use of a combined analytical and numerical integration over a sequence simplifying transformations of the feature space. The results are compared with those obtained by conventional techniques applied to a 2-class 4-feature discrimination problem with results previously reported and 4-class 4-feature multispectral scanner Landsat data classified by training and testing of the available data.

  6. Artificial intelligence techniques for scheduling Space Shuttle missions

    NASA Technical Reports Server (NTRS)

    Henke, Andrea L.; Stottler, Richard H.

    1994-01-01

    Planning and scheduling of NASA Space Shuttle missions is a complex, labor-intensive process requiring the expertise of experienced mission planners. We have developed a planning and scheduling system using combinations of artificial intelligence knowledge representations and planning techniques to capture mission planning knowledge and automate the multi-mission planning process. Our integrated object oriented and rule-based approach reduces planning time by orders of magnitude and provides planners with the flexibility to easily modify planning knowledge and constraints without requiring programming expertise.

  7. Numerical simulation of drifting snow sublimation in the saltation layer

    PubMed Central

    Dai, Xiaoqing; Huang, Ning

    2014-01-01

    Snow sublimation is an important hydrological process and one of the main causes of the temporal and spatial variation of snow distribution. Compared with surface sublimation, drifting snow sublimation is more effective due to the greater surface exposure area of snow particles in the air. Previous studies of drifting snow sublimation have focused on suspended snow, and few have considered saltating snow, which is the main form of drifting snow. In this study, a numerical model is established to simulate the process of drifting snow sublimation in the saltation layer. The simulated results show 1) the average sublimation rate of drifting snow particles increases linearly with the friction velocity; 2) the sublimation rate gradient with the friction velocity increases with increases in the environmental temperature and the undersaturation of air; 3) when the friction velocity is less than 0.525 m/s, the snowdrift sublimation of saltating particles is greater than that of suspended particles; and 4) the snowdrift sublimation in the saltation layer is less than that of the suspended particles only when the friction velocity is greater than 0.625 m/s. Therefore, the drifting snow sublimation in the saltation layer constitutes a significant portion of the total snow sublimation. PMID:25312383

  8. A High Performance Image Data Compression Technique for Space Applications

    NASA Technical Reports Server (NTRS)

    Yeh, Pen-Shu; Venbrux, Jack

    2003-01-01

    A highly performing image data compression technique is currently being developed for space science applications under the requirement of high-speed and pushbroom scanning. The technique is also applicable to frame based imaging data. The algorithm combines a two-dimensional transform with a bitplane encoding; this results in an embedded bit string with exact desirable compression rate specified by the user. The compression scheme performs well on a suite of test images acquired from spacecraft instruments. It can also be applied to three-dimensional data cube resulting from hyper-spectral imaging instrument. Flight qualifiable hardware implementations are in development. The implementation is being designed to compress data in excess of 20 Msampledsec and support quantization from 2 to 16 bits. This paper presents the algorithm, its applications and status of development.

  9. Sublimed C60 films for tribology

    NASA Astrophysics Data System (ADS)

    Bhushan, Bharat; Gupta, B. K.; Van Cleef, Garrett W.; Capp, Cindy; Coe, James V.

    1993-06-01

    Fullerenes take the form of hollow, geodesic domes, which are formed from a network of pentagons and hexagons. The C60 molecule has the highest possible symmetry (icosahedral) and assumes the shape of a soccer ball. At room temperature, fullerene molecules pack in a face-centered-cubic lattice bonded with weak van der Waals attractions. Fullerenes can be dissolved in solvents such as toluene and benzene and easily sublimed. The resilience, high load bearing capacity, low surface energy, high chemical stability, and spherical shape of C60 molecules and weak intermolecular bonding offer great potential for various mechanical and tribological applications. Sublimed films of C60 have been produced and friction and wear performance of these films in various operating environments are the subject of this letter.

  10. Psychotherapy. Sublimation and the psychodynamics of birding.

    PubMed

    Clemens, Norman A

    2012-07-01

    An adventure in extreme birding prompted the psychoanalyst author to reflect on "why do people do this?" Like myriad human interests, vocations, and avocations, the activity of bird watching is a socially acceptable activity that is the final pathway for multiple motivations that are likely to have a long history in the individual's development. It may have origins in basic survival skills. Various psychological defense mechanisms may be involved, the most mature and successful one being sublimation. Success of a defense-like sublimation may be viewed in terms of freedom from anxiety or from obsessive extremes that interfere with the individual's wellbeing, important relationships, or physical or financial health. The author considers whether the characters in the film The Big Year exemplify such success or the lack of it. PMID:22805903

  11. No reduction using sublimation of cyanuric acid

    DOEpatents

    Perry, Robert

    1989-01-01

    An arrangement for reducing the NO content of a gas stream comprises contacting the gas stream with HNCO at a temperature effective for heat induced decomposition of HNCO and for resultant lowering of the NO content of the gas stream. Preferably, the HNCO is generated by sublimation of cyanuric acid and CO or other H-atom generating species is also present or added to the gas stream.

  12. Co-location of space geodetics techniques in Space and on the ground

    NASA Astrophysics Data System (ADS)

    Kodet, J.; Plötz, Chr.; Schreiber, K. U.; Neidhardt, A.; Pogrebenko, S.; Haas, R.; Molera, G.; Prochazka, I.

    2013-08-01

    The most demanding goal of the Global Geodetic Observing System (GGOS) initiative is the definition of station positions to an accuracy of 1 mm and the corresponding velocities to 0.1 mm/year. Fundamental stations are core sites in this respect, because they collocate the geodetic relevant space techniques. However this requires unprecedented control over local ties, intra- and inter-technique biases. To improve the accuracy of the geodetic techniques, new concepts for the monitoring and controlling of local ties and biases have to be implemented. We are developing a symmetric two-way measurement technique to identify unaccounted system delays within and between the instrumentation of the Geodetic Observatory Wettzell. It requires redesign of the VLBI (Very Long Baseline Interferometry) phase calibration generator to be compatible with such an two-way measurement technique and VLBI2010. Another activity is the mapping of Global Navigation Satellite System (GNSS) satellites into the frame of the quasars using VLBI telescope, in geodetic mode. This corresponds to a collocation of geodetic techniques in space.The receiver of the 20 m radio telescope Wettzell (RTW) has been modified to measure the GNSS L1 signal without changing the physical reference point. Preliminary experiments have already been executed.

  13. Space Geodetic Technique Co-location in Space: Simulation Results for the GRASP Mission

    NASA Astrophysics Data System (ADS)

    Kuzmicz-Cieslak, M.; Pavlis, E. C.

    2011-12-01

    The Global Geodetic Observing System-GGOS, places very stringent requirements in the accuracy and stability of future realizations of the International Terrestrial Reference Frame (ITRF): an origin definition at 1 mm or better at epoch and a temporal stability on the order of 0.1 mm/y, with similar numbers for the scale (0.1 ppb) and orientation components. These goals were derived from the requirements of Earth science problems that are currently the international community's highest priority. None of the geodetic positioning techniques can achieve this goal alone. This is due in part to the non-observability of certain attributes from a single technique. Another limitation is imposed from the extent and uniformity of the tracking network and the schedule of observational availability and number of suitable targets. The final limitation derives from the difficulty to "tie" the reference points of each technique at the same site, to an accuracy that will support the GGOS goals. The future GGOS network will address decisively the ground segment and to certain extent the space segment requirements. The JPL-proposed multi-technique mission GRASP (Geodetic Reference Antenna in Space) attempts to resolve the accurate tie between techniques, using their co-location in space, onboard a well-designed spacecraft equipped with GNSS receivers, a SLR retroreflector array, a VLBI beacon and a DORIS system. Using the anticipated system performance for all four techniques at the time the GGOS network is completed (ca 2020), we generated a number of simulated data sets for the development of a TRF. Our simulation studies examine the degree to which GRASP can improve the inter-technique "tie" issue compared to the classical approach, and the likely modus operandi for such a mission. The success of the examined scenarios is judged by the quality of the origin and scale definition of the resulting TRF.

  14. Techniques and Tools of NASA's Space Shuttle Columbia Accident Investigation

    NASA Technical Reports Server (NTRS)

    McDanels, Steve J.

    2005-01-01

    The Space Shuttle Columbia accident investigation was a fusion of many disciplines into a single effort. From the recovery and reconstruction of the debris, Figure 1, to the analysis, both destructive and nondestructive, of chemical and metallurgical samples, Figure 2, a multitude of analytical techniques and tools were employed. Destructive and non-destructive testing were utilized in tandem to determine if a breach in the left wing of the Orbiter had occurred, and if so, the path of the resultant high temperature plasma flow. Nondestructive analysis included topometric scanning, laser mapping, and real-time radiography. These techniques were useful in constructing a three dimensional virtual representation of the reconstruction project, specifically the left wing leading edge reinforced carbon/carbon heat protectant panels. Similarly, they were beneficial in determining where sampling should be performed on the debris. Analytic testing included such techniques as Energy Dispersive Electron Microprobe Analysis (EMPA), Electron Spectroscopy Chemical Analysis (ESCA), and X-Ray dot mapping; these techniques related the characteristics of intermetallics deposited on the leading edge of the left wing adjacent to the location of a suspected plasma breach during reentry. The methods and results of the various analyses, along with their implications into the accident, are discussed, along with the findings and recommendations of the Columbia Accident Investigation Board. Likewise, NASA's Return To Flight efforts are highlighted.

  15. New method for estimating bacterial cell abundances in natural samples by use of sublimation

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Cleaves, H. James; Schubert, Michael; Aubrey, Andrew; Bada, Jeffrey L.

    2004-01-01

    We have developed a new method based on the sublimation of adenine from Escherichia coli to estimate bacterial cell counts in natural samples. To demonstrate this technique, several types of natural samples, including beach sand, seawater, deep-sea sediment, and two soil samples from the Atacama Desert, were heated to a temperature of 500 degrees C for several seconds under reduced pressure. The sublimate was collected on a cold finger, and the amount of adenine released from the samples was then determined by high-performance liquid chromatography with UV absorbance detection. Based on the total amount of adenine recovered from DNA and RNA in these samples, we estimated bacterial cell counts ranging from approximately 10(5) to 10(9) E. coli cell equivalents per gram. For most of these samples, the sublimation-based cell counts were in agreement with total bacterial counts obtained by traditional DAPI (4,6-diamidino-2-phenylindole) staining.

  16. Core-shell-like Y2O3:[(Tb3+-Yb3+), Li+]/CdZnS heterostructure synthesized by super-close-space sublimation for broadband down-conversion

    NASA Astrophysics Data System (ADS)

    Wu, Xiaojie; Zhang, Zhenzhong; Meng, Fanzhi; Yu, Yingning; Han, Lin; Liu, Xiaojuan; Meng, Jian

    2014-04-01

    Combination with semiconductors is a promising approach to the realization of broadband excitation of light conversion materials based on rare earth compounds, to boost the energy efficiency of silicon solar cells. Cd1-xZnxS is a wide bandgap semiconductor with large exciton binding energy. By changing its composition, the bandgap of Cd1-xZnxS can be tuned to match the absorption of trivalent lanthanide (Ln) ions, which makes it a competent energy donor for the Ln3+-Yb3+ couple. In this work, we designed a clean route to a broadband down-converter based on a core-shell-like Y2O3:[(Tb3+-Yb3+), Li+]/Cd0.81Zn0.19S (CdZnS) heterostructure. By hot-pressing and subsequent annealing of a Y2O3:[(Tb3+-Yb3+), Li+]/CdZnS mixture, highly pure CdZnS was sublimated and deposited on the Y2O3:[(Tb3+-Yb3+), Li+] grains while maintaining the original composition of the precursor. The CdZnS shell acted as a light absorber and energy donor for the Tb3+-Yb3+ quantum cutting couple. Because the use of solvents was avoided during the formation of the heterostructures, few impurities were incorporated into the samples, and the non-radiative transition was therefore markedly suppressed. The Y2O3:[(Tb3+-Yb3+), Li+]/CdZnS heterostructures possess strong near-infrared (NIR) luminescence from Yb3+. Broadband down-conversion to the Yb3+ NIR emission was obtained in a wide range of 250-650 nm.

  17. Undergraduate Laboratory Experiment Facilitating Active Learning of Concepts in Transport Phenomena: Experiment with a Subliming Solid

    ERIC Educational Resources Information Center

    Utgikar, Vivek P.

    2015-01-01

    An experiment based on the sublimation of a solid was introduced in the undergraduate Transport Phenomena course. The experiment required the students to devise their own apparatus and measurement techniques. The theoretical basis, assignment of the experiment, experimental results, and student/instructor observations are described in this paper.…

  18. Co-location of space geodetics techniques in Space and on the ground

    NASA Astrophysics Data System (ADS)

    Kodet, Jan; Plötz, Christian; Schreiber, Ulrich

    2013-04-01

    The most demanding goal of the GGOS initiative is the definition of station positions to an accuracy of 1mm and the corresponding velocities to 0.1mm/year. The main remaining sources of error are caused by systematics, leading to intra- and inter- technique biases. To improve the accuracy of the geodetic techniques, new concepts for monitoring and controlling local ties and biases have to be implemented. We are developing a symmetric two-way measurement technique to identify unaccounted system delays within and between the instrumentation of the Geodetic Observatory Wettzell. Another activity is the mapping of GNSS satellites into the frame of the quasars using VLBI (Very Long Baseline Interferometry) telescope, in geodetic mode. This corresponds to a collocation of geodetic techniques in space. The receiver of the Wettzell 20m antenna has been modified to measure the GNSS L1 signal without changing the local ties. Preliminary experiments have been executed already.

  19. Application of Space Geodetic Techniques to Weather and Climate

    NASA Astrophysics Data System (ADS)

    Yunck, T. P.

    2003-04-01

    With the emergence of large-scale geodetic ground networks, both regional and global, and affordable spaceborne GPS scientific receivers, space geodetic techniques are finding diverse and unexpected new applications in many areas of Earth remote sensing. Basic GPS navigation receivers are now all but indispensable to low earth orbiting missions of all kinds. Science applications of spaceborne GPS today include centimeter-level precise orbit determination for gravity mapping, ocean altimetry, geocenter detection, and enhanced global geodesy; high resolution 3D imaging of the global ionosphere; occultation limb sounding to recover precise profiles of atmospheric refractivity, density, pressure, temperature, water vapor, and geopotential heights; and the experimental detection of GPS ocean reflections for direct ocean altimetry and scatterometry. In the past five years there has been an explosion in the use of both ground and spaceborne geodetic receivers for direct sensing of the atmosphere to provide data for weather prediction and research in global climate change. Atmospheric applications of space geodesy are generating increasing scientific interest. Dense GPS networks in Japan, North America, Scandinavia, Europe, and elsewhere are now routinely providing data for assimilation into daily weather forecasts. A constellation of six orbiting occultation receivers, such as the COSMIC mission to be launched in 2005, can measure atmospheric refractivity with a precision equivalent to 0.1 K in temperature within a climate region corresponding to 1/30 the earth's surface, with just a few weeks of data. Vertical resolution can reach below a hundred meters. This offers perhaps the most promising approach yet to detecting and discriminating among subtle forced climatic signals, which may amount to only a few tenths of a Kelvin average temperature change per decade. This presentation will survey the techniques and applications of GPS atmospheric sensing from the ground and

  20. Space Shuttle stability and control flight test techniques

    NASA Technical Reports Server (NTRS)

    Cooke, D. R.

    1980-01-01

    A unique approach for obtaining vehicle aerodynamic characteristics during entry has been developed for the Space Shuttle. This is due to the high cost of Shuttle testing, the need to open constraints for operational flights, and the fact that all flight regimes are flown starting with the first flight. Because of uncertainties associated with predicted aerodynamic coefficients, nine flight conditions have been identified at which control problems could occur. A detailed test plan has been developed for testing at these conditions and is presented. Due to limited testing, precise computer initiated maneuvers are implemented. These maneuvers are designed to optimize the vehicle motion for determining aerodynamic coefficients. Special sensors and atmospheric measurements are required to provide stability and control flight data during an entire entry. The techniques employed in data reduction are proven programs developed and used at NASA/DFRC.

  1. Overview of arraying techniques in the deep space network

    NASA Technical Reports Server (NTRS)

    Mileant, A.; Hinedi, S.

    1991-01-01

    Four different arraying schemes that can be used by the Deep Space Network are functionally discussed and compared. These include symbol stream combining (SSC), baseband combining (BC), carrier arraying (CA), and full spectrum combining (FSC). In addition, sibeband aiding (SA) is also included and compared even though it is not an arraying scheme, since it uses a single antenna. Moreover, combinations of these schemes are discussed, such as carrier arraying with sideband aiding and baseband combining (CA/SA/BC) or carrier arraying with symbol stream combining (CA/SSC). Complexity versus performance is traded off and the benefits to the reception of existing spacecraft signals are discussed. Recommendations are made as to the best techniques for particular configurations.

  2. An improved astrometric calibration technique for space debris observation

    NASA Astrophysics Data System (ADS)

    Sun, Rong-Yu; Zhao, Chang-Yin; Lu, Yao

    2016-02-01

    An optical survey is the main technique for detecting space debris. Due to the specific characteristics of observation, the pointing errors and tracking errors of the telescope as well as image degradation may be significant, which make it difficult for astrometric calibration. Here we present an improved method that corrects the pointing and tracking errors, and measures the image position precisely. The pipeline is tested on a number of CCD images obtained from a 1-m telescope administered by Xinjiang Astronomical Observatory while observing a GPS satellite. The results show that the position measurement error of the background stars is around 0.1 pixel, while the time cost for a single frame is about 7.5 s; hence the reliability and accuracy of our method are demonstrated. In addition, our method shows a versatile and feasible way to perform space debris observation utilizing non-dedicated telescopes, which means more sensors could be involved and the ability to perform surveys could be improved.

  3. Science Sublime: The Philosophy of the Sublime, Dewey's Aesthetics, and Science Education

    ERIC Educational Resources Information Center

    Cavanaugh, Shane

    2014-01-01

    Feelings of awe, wonder, and appreciation have been largely ignored in the working lives of scientists and, in turn, science education has not accurately portrayed science to students. In an effort to bring the affective qualities of science into the classroom, this work draws on the writings of the sublime by Burke, Kant, Emerson, and Wordsworth…

  4. Objective techniques for psychological assessment, phase 2. [techniques for measuring human performance during space flight stress

    NASA Technical Reports Server (NTRS)

    Wortz, E. C.; Saur, A. J.; Nowlis, D. P.; Kendall, M. P.

    1974-01-01

    Results are presented of an initial experiment in a research program designed to develop objective techniques for psychological assessment of individuals and groups participating in long-duration space flights. Specifically examined is the rationale for utilizing measures of attention as an objective assessment technique. Subjects participating in the experiment performed various tasks (eg, playing matrix games which appeared on a display screen along with auditory stimuli). The psychophysiological reactions of the subjects were measured and are given. Previous research of various performance and psychophysiological methods of measuring attention is also discussed. The experiment design (independent and dependent variables) and apparatus (computers and display devices) are described and shown. Conclusions and recommendations are presented.

  5. A Comparison Between Orion Automated and Space Shuttle Rendezvous Techniques

    NASA Technical Reports Server (NTRS)

    Ruiz, Jose O,; Hart, Jeremy

    2010-01-01

    architecture and contrast it with shuttle rendezvous techniques and circumstances. The shuttle rendezvous profile is timed to take approximately 3 days from orbit insertion to docking at the International Space Station (ISS). This process can be divided into 3 phases: far-field, mid-field and proximity operations. The far-field stage is characterized as the most quiescent phase. The spacecraft is usually too far to navigate using relative sensors and uses the Inertial Measurement Units (IMU s) to numerically solve for its position. The maneuvers are infrequent, roughly twice per day, and are larger than other burns in the profile. The shuttle uses this opportunity to take extensive ground based radar updates and keep high fidelity orbit states on the ground. This state is then periodically uplinked to the shuttle computers. The targeting solutions for burn maneuvers are also computed on the ground and uplinked. During the burn the crew is responsible for setting the shuttle attitude and configuring the propulsion system for ignition. Again this entire process is manually driven by both crew and ground activity. The only automatic processes that occur are associated with the real-time execution of the burn. The Orion automated functionality will seek to relieve the workload of both the crew and ground during this phase

  6. Applications of dynamic scheduling technique to space related problems: Some case studies

    NASA Technical Reports Server (NTRS)

    Nakasuka, Shinichi; Ninomiya, Tetsujiro

    1994-01-01

    The paper discusses the applications of 'Dynamic Scheduling' technique, which has been invented for the scheduling of Flexible Manufacturing System, to two space related scheduling problems: operation scheduling of a future space transportation system, and resource allocation in a space system with limited resources such as space station or space shuttle.

  7. Applications of dynamic scheduling technique to space related problems: Some case studies

    NASA Astrophysics Data System (ADS)

    Nakasuka, Shinichi; Ninomiya, Tetsujiro

    1994-10-01

    The paper discusses the applications of 'Dynamic Scheduling' technique, which has been invented for the scheduling of Flexible Manufacturing System, to two space related scheduling problems: operation scheduling of a future space transportation system, and resource allocation in a space system with limited resources such as space station or space shuttle.

  8. AI techniques for a space application scheduling problem

    NASA Technical Reports Server (NTRS)

    Thalman, N.; Sparn, T.; Jaffres, L.; Gablehouse, D.; Judd, D.; Russell, C.

    1991-01-01

    Scheduling is a very complex optimization problem which can be categorized as an NP-complete problem. NP-complete problems are quite diverse, as are the algorithms used in searching for an optimal solution. In most cases, the best solutions that can be derived for these combinatorial explosive problems are near-optimal solutions. Due to the complexity of the scheduling problem, artificial intelligence (AI) can aid in solving these types of problems. Some of the factors are examined which make space application scheduling problems difficult and presents a fairly new AI-based technique called tabu search as applied to a real scheduling application. the specific problem is concerned with scheduling application. The specific problem is concerned with scheduling solar and stellar observations for the SOLar-STellar Irradiance Comparison Experiment (SOLSTICE) instrument in a constrained environment which produces minimum impact on the other instruments and maximizes target observation times. The SOLSTICE instrument will gly on-board the Upper Atmosphere Research Satellite (UARS) in 1991, and a similar instrument will fly on the earth observing system (Eos).

  9. Development of CFRP Mirrors for Space Telescopes Using Replica Technique

    NASA Astrophysics Data System (ADS)

    Utsunomiya, Shin; Kamiya, Tomohiro; Shimizu, Ryuzo

    2012-07-01

    Ultra-lightweight and high-accuracy CFRP (Carbon Fiber Reinforced Plastics) mirrors for space telescopes have developed and their feasibility for ultrared applications was demonstrated. The CTE (Coefficient of Thermal Expansion) of the all-CFRP sandwich panels was tailored in ±1x10-7/K. The surface accuracy of mirrors of 150 mm in diameter was 0.8 μm RMS (Root Mean Square) as fabricated and the surface smoothness was improved to 5 nm RMS. The surface of front face skins of sandwich panels was coated with epoxy resin and surface accuracy and smoothness were transcribed from an optically-polished glass tool of λ/20 accuracy by replica technique. Surface preciseness was measured before and after replica coating using a 3D optical profiler of white light interferometer. Observed patterns of the asperity of mirror surfaces were classified into four categories, overall warping and line patterns of fiber tows and core patterns and print-through of individual fibers. Replica improved all kinds of asperity.

  10. Shroud debris modeling techniques for IR sensors in space

    NASA Astrophysics Data System (ADS)

    VanderWyst, Anton; Jenkins, David G.; Ahmad, Anees

    2007-09-01

    Space-based surveillance sensors are covered by a shroud to protect the delicate optics from adverse environments (aerothermal heating and contamination) during hypersonic flight through the atmosphere. Once the sensor payload reaches a safe altitude, the shroud is deployed and then sensor operation begins. When the pyrotechnic actuators are fired to deploy the shroud or nosecone, large and microscopic particles are dislodged. The source of these particles is the charred thermal protection insulation material on outer surface of the shroud, and particulate contaminants deposited on the inside surface of shroud and on sensor components during assembly process. These dislodged particles can end up within the sensor field of view (FOV), and remain there for extended periods of time, with the duration depending on the air density and vehicle velocity. These undesirable particles within the sensor FOV can degrade infrared sensor performance in several ways. These particles can cause obscuration, scattering and produce spurious thermal signature, thus making it difficult to image the objects of interest. This paper presents the aeromodeling techniques used to estimate the number and size of particles, and the duration these particles can stay within the sensor FOV. This information can then be used to predict the resulting degradation in sensor performance.

  11. Application of ion beam analysis to the selective sublimation processing of thin films for gas sensing

    NASA Astrophysics Data System (ADS)

    Vomiero, A.; Scian, C.; Della Mea, G.; Guidi, V.; Martinelli, G.; Schiffrer, G.; Comini, E.; Ferroni, M.; Sberveglieri, G.

    2006-08-01

    Ion beam analysis was successfully applied to a novel technique, named selective sublimation process (SSP), for deposition of nanostructured gas-sensing films through reactive sputtering. The method consists of the co-deposition of a mixed oxide, one of which has a relatively low sublimation temperature. Annealing at suitable temperature causes the sublimation of the most volatile compound, leaving a layer with adjustable composition. The appropriate choice of thermal treatments and the consequent tailoring of the composition play a crucial role in the determination of the microstructural properties. We developed a model based on diffusion equations that provides a useful guide to control the deposition and processing parameters and we applied the model on the systems TiO2-WO3 and TiO2-MoO3. Rutherford backscattering (RBS) was demonstrated to be effective for the characterization of the diffusion and sublimation processes during SSP. Experimental results fully agree with theoretical prediction, and allowed the calculation of all the parameters involved in SSP.

  12. Reassessing Aesthetic Appreciation of Nature in the Kantian Sublime

    ERIC Educational Resources Information Center

    Brady, Emily

    2012-01-01

    The sublime has been a relatively neglected topic in recent work in philosophical aesthetics, with existing discussions confined mainly to problems in Kant's theory. Given the revival of interest in his aesthetic theory and the influence of the Kantian sublime compared to other eighteenth-century accounts, this focus is not surprising. Kant's…

  13. Generalized Orbital Projections of a Sublimating Ice Particle

    NASA Technical Reports Server (NTRS)

    Menkin, Evgeny; Bacon, Jack

    2006-01-01

    The issue of orbital debris resulting from human activities in space is a growing concern for the space users' community. Waste generated in Low Earth Orbit (LEO) can stay in orbit for a long time, creating significant hazards for other spacecraft flying at lower intercepting orbits. Many spacecraft, especially crewed vehicles, are required to vent fluids into space. These fluids include propellant, wastewater, excess condensate, and others. It is important to analyze the behavior of particles that result from these activities, since each individual particle is capable of damaging or destroying a spacecraft in a lower, crossing orbit, and such particles are invisible to tracking radar systems on the ground. The deorbit trajectory of an ice particle is complex. It depends on factors including attitude of the vehicle during vent, initial velocities of particles, altitude at which the vent occurred, and numerous evaporation and sublimation factors. These include contamination within the vented water, evolution of bubbles within the clear water, and sun flux factors such as time of the year and current beta angle. The purpose of this study is to examine the influences of these factors on the trajectories of ice particles resulting from condensate water dumps, and to bound the safe trajectories of spacecraft that lie below the venting spacecraft.

  14. Sublimation Growth of Titanium Nitride Crystals

    SciTech Connect

    Du, Li; Edgar, J H; Kenik, Edward A; Meyer III, Harry M

    2009-01-01

    The sublimation-recondensation growth of titanium nitride crystal with N/Ti ratio of 0.99 on tungsten substrate is reported. The growth rate dependence on temperature and pressure was determined, and the calculated activation energy is 775.8 29.8kJ/mol. The lateral and vertical growth rates changed with the time of growth and the fraction of the tungsten substrate surface covered. The orientation relationship of TiN (001) || W (001) with TiN [100] || W [110], a 45o angle between TiN [100] and W [100], occurs not only for TiN crystals deposited on W (001) textured tungsten but also for TiN crystals deposited on randomly orientated tungsten. This study demonstrates that this preferred orientational relationship minimizes the lattice mismatch between the TiN and tungsten.

  15. Sublimation of ice-tholins mixtures: A morphological and spectro-photometric study

    NASA Astrophysics Data System (ADS)

    Poch, Olivier; Pommerol, Antoine; Jost, Bernhard; Carrasco, Nathalie; Szopa, Cyril; Thomas, Nicolas

    2016-03-01

    Sublimation, the direct transition from solid to gas phase, is a process responsible for shaping and changing the reflectance properties of many Solar System surfaces. In this study, we have characterized the evolution of the structure/texture and of the visible and near-infrared (VIS-NIR) spectral reflectance of surfaces made of water ice mixed with analogues of complex extraterrestrial organic matter, named tholins, under low temperature (<-70 °C) and pressure (10-5 mbar) conditions. The experiments were carried out in the SCITEAS simulation setup recently built as part of the Laboratory for Outflow Studies of Sublimating Materials (LOSSy) at the University of Bern (Pommerol, A. et al. [2015a]. Planet. Space Sci. 109-110, 106-122). As the water ice sublimated, we observed in situ the formation of a sublimation lag deposit made of a water-free porous (>90% porosity) network of organic filaments on top of the ice. The temporal evolution of the tholins and water ice spectral features (reflectance at the absorption bands wavelengths, red slope, from 0.40 to 1.90 μm) are analyzed throughout the sublimation of the samples. We studied how different mixtures of tholins with water (0.1 wt.% tholins as coating or inclusions within the water particles), and different ice particle sizes (4.5 ± 2.5 or 67 ± 31 μm) influence the morphological and spectral evolutions of the samples. The sublimation of the ice below the mantle produces a gas flow responsible for the ejection of mm to cm-sized fragments of the deposit in outbursts-like events. The results show remarkable differences between these samples in term of mantle structure, speed of mantle building, rates and surface area of mantle ejections. These data provide useful references for interpreting remote-sensing observations of icy Solar System surfaces, in particular the activity of comet nuclei where sublimation of organic-rich ices and deposition of organic-dust particles likely play a major role. Consequently, the

  16. Sublime science: Teaching for scientific sublime experiences in middle school classrooms

    NASA Astrophysics Data System (ADS)

    Cavanaugh, Shane

    Due to a historical separation of cognition and emotion, the affective aspects of learning are often seen as trivial in comparison to the more 'essential' cognitive qualities - particularly in the domain of science. As a result of this disconnect, feelings of awe, wonder, and astonishment as well as appreciation have been largely ignored in the working lives of scientists. In turn, I believe that science education has not accurately portrayed the world of science to our students. In an effort to bring the affective qualities of science into the science classroom, I have drawn on past research in the field of aesthetic science teaching and learning as well as works by, Burke, Kant, and Dewey to explore a new construct I have called the "scientific sublime". Scientific sublime experiences represent a sophisticated treatment of the cognitive as well as affective qualities of science learning. The scientific sublime represents feelings of awe, wonder, and appreciation that come from a deep understanding. It is only through this understanding of a phenomenon that we can appreciate its true complexity and intricacies, and these understandings when mixed with the emotions of awe and reverence, are sublime. Scientific sublime experiences are an attempt at the re-integration of cognition and feeling. The goal of this research was twofold: to create and teach a curriculum that fosters scientific sublime experiences in middle school science classes, and to better understand how these experiences are manifested in students. In order to create an approach to teaching for scientific sublime experiences, it was first necessary for me to identify key characteristics of such an experience and a then to create a pedagogical approach, both of which are described in detail in the dissertation. This research was conducted as two studies in two different middle schools. My pedagogical approach was used to create and teach two five-week 7 th grade science units---one on weather

  17. Prediction of Sublimation Pressures of Low Volatility Solids

    NASA Astrophysics Data System (ADS)

    Drake, Bruce Douglas

    Sublimation pressures are required for solid-vapor phase equilibrium models in design of processes such as supercritical fluid extraction, sublimation purification and vapor epitaxy. The objective of this work is to identify and compare alternative methods for predicting sublimation pressures. A bibliography of recent sublimation data is included. Corresponding states methods based on the triple point (rather than critical point) are examined. A modified Trouton's rule is the preferred method for estimating triple point pressure in the absence of any sublimation data. Only boiling and melting temperatures are required. Typical error in log_{10} P _{rm triple} is 0.3. For lower temperature estimates, the slope of the sublimation curve is predicted by a correlation based on molar volume. Typical error is 10% of slope. Molecular dynamics methods for surface modeling are tested as estimators of vapor pressure. The time constants of the vapor and solid phases are too different to allow the vapor to come to thermal equilibrium with the solid. The method shows no advantages in prediction of sublimation pressure but provides insight into appropriate models and experimental methods for sublimation. Density-dependent augmented van der Waals equations of state based on hard-sphere distribution functions are examined. The perturbation term is almost linear and is well fit by a simple quadratic. Use of the equation provides reasonable fitting of sublimation pressures from one data point. Order-of-magnitude estimation is possible from melting temperature and solid molar volume. The inverse -12 fluid is used to develop an additional equation of state. Sublimation pressure results, including quality of pressure predictions, are similar to the hard-sphere results. Three-body (Axilrod -Teller) interactions are used to improve results.

  18. New Factorization Techniques and Fast Serial and Parrallel Algorithms for Operational Space Control of Robot Manipulators

    NASA Technical Reports Server (NTRS)

    Fijany, Amir; Djouani, Karim; Fried, George; Pontnau, Jean

    1997-01-01

    In this paper a new factorization technique for computation of inverse of mass matrix, and the operational space mass matrix, as arising in implementation of the operational space control scheme, is presented.

  19. Three-dimensional textures and defects of soft material layering revealed by thermal sublimation

    PubMed Central

    Yoon, Dong Ki; Kim, Yun Ho; Kim, Dae Seok; Oh, Seong Dae; Smalyukh, Ivan I.; Clark, Noel A.; Jung, Hee-Tae

    2013-01-01

    Layering is found and exploited in a variety of soft material systems, ranging from complex macromolecular self-assemblies to block copolymer and small-molecule liquid crystals. Because the control of layer structure is required for applications and characterization, and because defects reveal key features of the symmetries of layered phases, a variety of techniques have been developed for the study of soft-layer structure and defects, including X-ray diffraction and visualization using optical transmission and fluorescence confocal polarizing microscopy, atomic force microscopy, and SEM and transmission electron microscopy, including freeze-fracture transmission electron microscopy. Here, it is shown that thermal sublimation can be usefully combined with such techniques to enable visualization of the 3D structure of soft materials. Sequential sublimation removes material in a stepwise fashion, leaving a remnant layer structure largely unchanged and viewable using SEM, as demonstrated here using a lamellar smectic liquid crystal. PMID:24218602

  20. Practical sublimation source for large-scale chromium gettering in fusion devices

    SciTech Connect

    Simpkins, J.E.; Emerson, L.C.; Mioduszewski, P.K.

    1983-01-01

    This paper describes the technique of chromium gettering with a large-scale sublimation source which resembles in its design the VARIAN Ti-Ball. It consists of a hollow chromium sphere with a diameter of approximately 3 cm and an incandescent filament for radiation heating from inside the ball. While the fabrication of the source is described in a companion paper, we discuss here the gettering technique. The experimental arrangement consists of an UHV system instrumented for total- and partial-pressure measurements, a film-thickness monitor, thermocouples, an optical pyrometer, and appropriate instrumentation to measure the heating power. The results show the temperature and corresponding sublimation rate of the Cr-Ball as function of input power. In addition, an example of the total pumping speed of a gettered surface is shown.

  1. The formation of filamentary sublimate residues (FSR) from mineral grains

    NASA Technical Reports Server (NTRS)

    Storrs, A. D.; Fanale, F. P.; Saunders, R. S.; Stephens, J. B.

    1988-01-01

    The significant interparticle forces observed between solar system dust grains upon desorption or sublimation of excess volatiles in simulated Martian or cometary environments are presently investigated, in order to more precisely define these mechanisms and to simulate the types of deposits thereby formed. Some classes of phyllosilicate mineral grains are noted to bond together to form a highly porous filamentary sublimate residue (FSR) exhibiting an exceptionally high tensile strength for its density; this may be important in its control of erosion and sublimation in Martian and cometary environments. It is concluded that FSR formation from clean mineral grains in water ice may be important in the formation of the Martian polar layered terrain.

  2. Key techniques for space-based solar pumped semiconductor lasers

    NASA Astrophysics Data System (ADS)

    He, Yang; Xiong, Sheng-jun; Liu, Xiao-long; Han, Wei-hua

    2014-12-01

    In space, the absence of atmospheric turbulence, absorption, dispersion and aerosol factors on laser transmission. Therefore, space-based laser has important values in satellite communication, satellite attitude controlling, space debris clearing, and long distance energy transmission, etc. On the other hand, solar energy is a kind of clean and renewable resources, the average intensity of solar irradiation on the earth is 1353W/m2, and it is even higher in space. Therefore, the space-based solar pumped lasers has attracted much research in recent years, most research focuses on solar pumped solid state lasers and solar pumped fiber lasers. The two lasing principle is based on stimulated emission of the rare earth ions such as Nd, Yb, Cr. The rare earth ions absorb light only in narrow bands. This leads to inefficient absorption of the broad-band solar spectrum, and increases the system heating load, which make the system solar to laser power conversion efficiency very low. As a solar pumped semiconductor lasers could absorb all photons with energy greater than the bandgap. Thus, solar pumped semiconductor lasers could have considerably higher efficiencies than other solar pumped lasers. Besides, solar pumped semiconductor lasers has smaller volume chip, simpler structure and better heat dissipation, it can be mounted on a small satellite platform, can compose satellite array, which can greatly improve the output power of the system, and have flexible character. This paper summarizes the research progress of space-based solar pumped semiconductor lasers, analyses of the key technologies based on several application areas, including the processing of semiconductor chip, the design of small and efficient solar condenser, and the cooling system of lasers, etc. We conclude that the solar pumped vertical cavity surface-emitting semiconductor lasers will have a wide application prospects in the space.

  3. Sulfur "Concrete" for Lunar Applications - Sublimation Concerns

    NASA Technical Reports Server (NTRS)

    Grugel, Richard N.; Toutanji, Houssam

    2006-01-01

    Melting sulfur and mixing it with an aggregate to form "concrete" is commercially well established and constitutes a material that is particularly well-suited for use in corrosive environments. Discovery of the mineral troilite (FeS) on the moon poses the question of extracting the sulfur for use as a lunar construction material. This would be an attractive alternative to conventional concrete as it does not require water. However, the viability of sulfur concrete in a lunar environment, which is characterized by lack of an atmosphere and extreme temperatures, is not well understood. Here it is assumed that the lunar ore can be mined, refined, and the raw sulfur melded with appropriate lunar regolith to form, for example, bricks. This study evaluates pure sulfur and two sets of small sulfur concrete samples that have been prepared using JSC-1 lunar stimulant and SiO2 powder as aggregate additions. Each set was subjected to extended periods in a vacuum environment to evaluate sublimation issues. Results from these experiments are presented and discussed within the context of the lunar environment.

  4. A study of trends and techniques for space base electronics

    NASA Technical Reports Server (NTRS)

    Trotter, J. D.; Wade, T. E.; Gassaway, J. D.

    1978-01-01

    Furnaces and photolithography related equipment were applied to experiments on double layer metal. The double layer metal activity emphasized wet chemistry techniques. By incorporating the following techniques: (1) ultrasonic etching of the vias; (2) premetal clean using a modified buffered hydrogen fluoride; (3) phosphorus doped vapor; and (4) extended sintering, yields of 98 percent were obtained using the standard test pattern. The two dimensional modeling problems have stemmed from, alternately, instability and too much computation time to achieve convergence.

  5. Superconducting magnet technique for ASTROMAG on the space station

    SciTech Connect

    Green, M.A.

    1987-09-01

    This paper describes superconducting magnet systems which could be used as part of a Particle Astrophysics Experiment ASTROMAG on the space station. This report deals with issues of superconductor selection (should one consider the use of high critical temperature superconductor.), magnet coil and cryostat design, and the cryogenic cooling system for the superconducting magnet. 12 refs., 7 figs., 6 tabs.

  6. Candidate space processing techniques for biomaterials other than preparative electrophoresis

    NASA Technical Reports Server (NTRS)

    Brooks, D. E.

    1976-01-01

    The advantages of performing the partition and countercurrent distribution (CCD) of cells in phase separated aqueous polymer systems under reduced gravity were assessed. Other possible applications considered for the space processing program include the freezing front separation of cells, adsorption of cells at the air-water interface, and the macrophage electrophoretic mobility test for cancer.

  7. Improved Space Object Observation Techniques Using CMOS Detectors

    NASA Astrophysics Data System (ADS)

    Schildknecht, T.; Hinze, A.; Schlatter, P.; Silha, J.; Peltonen, J.; Santti, T.; Flohrer, T.

    2013-08-01

    CMOS-sensors, or in general Active Pixel Sensors (APS), are rapidly replacing CCDs in the consumer camera market. Due to significant technological advances during the past years these devices start to compete with CCDs also for demanding scientific imaging applications, in particular in the astronomy community. CMOS detectors offer a series of inherent advantages compared to CCDs, due to the structure of their basic pixel cells, which each contain their own amplifier and readout electronics. The most prominent advantages for space object observations are the extremely fast and flexible readout capabilities, feasibility for electronic shuttering and precise epoch registration, and the potential to perform image processing operations on-chip and in real-time. Presently applied and proposed optical observation strategies for space debris surveys and space surveillance applications had to be analyzed. The major design drivers were identified and potential benefits from using available and future CMOS sensors were assessed. The major challenges and design drivers for ground-based and space-based optical observation strategies have been analyzed. CMOS detector characteristics were critically evaluated and compared with the established CCD technology, especially with respect to the above mentioned observations. Similarly, the desirable on-chip processing functionalities which would further enhance the object detection and image segmentation were identified. Finally, the characteristics of a particular CMOS sensor available at the Zimmerwald observatory were analyzed by performing laboratory test measurements.

  8. Nietzsche's View of Sublimation in the Educational Process

    ERIC Educational Resources Information Center

    Sharp, Ann Margaret

    1975-01-01

    Article outlined Nietzsche's beliefs on the primary aim of education, the conscious production of the free man through the process of sublimation, the active redirecting of one's life energy in the service of creativity. (Editor/RK)

  9. Mass spectrometry study of the sublimation of aliphatic dipeptides

    NASA Astrophysics Data System (ADS)

    Badelin, V. G.; Tyunina, E. Yu.; Krasnov, A. V.; Tyunina, V. V.; Giricheva, N. I.; Girichev, A. V.

    2012-03-01

    The sublimation of glycyl-L-α-alanine (Gly-Ala), L-α-alanyl-L-α-alanine (Ala-Ala), and DL-α-alanyl-DL-α-valine (Ala-Val) aliphatic dipeptides is studied by electron ionization mass spectrometry in combination with Knudsen effusion. The temperature range in which substances sublime as monomer molecular forms is determined. Enthalpies of sublimation Δs H°( T) are determined for Gly-Ala, Ala-Ala, and Ala-Val. It is shown that the enthalpy of sublimation of dipeptides increases with an increase in the side hydrocarbon radical. The unknown Δs H°(298) values for 17 amino acids and nine dipeptides are estimated using the proposed "structure-property" correlation model, in which the geometry and electron characteristics of molecules are used as structural descriptors.

  10. Dynamics and Mechanisms of Exfoliated Black Phosphorus Sublimation.

    PubMed

    Fortin-Deschênes, Matthieu; Levesque, Pierre L; Martel, Richard; Moutanabbir, Oussama

    2016-05-01

    We report on real time observations of the sublimation of exfoliated black phosphorus layers throughout annealing using in situ low energy electron microscopy. We found that sublimation manifests itself above 375 ± 20 °C through the nucleation and expansion of asymmetric, faceted holes with the long axis aligned along the [100] direction and sharp tips defined by edges consisting of alternating (10) and (11) steps. This thermally activated process repeats itself via successive sublimation of individual layers. Calculations and simulations using density functional theory and kinetic Monte Carlo allowed to determine the involved atomic pathways. Sublimation is found to occur via detachments of phosphorus dimers rather than single atoms. This behavior and the role of defects is described using an analytical model that captures all essential features. This work establishes an atomistic-level understanding of the thermal stability of exfoliated black phosphorus and defines the temperature window available for material and device processing. PMID:27097073

  11. Scanning electron microscope observations of sublimates from Merapi Volcano, Indonesia

    USGS Publications Warehouse

    Symonds, R.

    1993-01-01

    Sublimates were sampled from high-temperature (up to 800??C) fumaroles at Merapi volcano in January 1984. Sampling is accomplished by inserting silica tubes into high-temperature vents. Volcanic glass flows through the tubes and sublimates precipitate on the inner walls in response to the temperature gradient. With decreasing temperature (800-500??C) in the tubes, there are five sublimate zones. Texturally, the sublimate phases grade from large, well-formed crystals at their highest-temperature occurrence to more numerous, smaller crystals that are less perfect at lower temperatures. These changes imply that the crystal nucleation and growth rates increase and decrease, respectively, as temperature decreases. Overall, the textural data suggest that the gas is saturated or slightly super-saturated with the phases at their hottest occurrence, but that the gas becomes increasingly super-saturated with the phases at lower temperatures. -from Author

  12. GSFC Space Simulation Laboratory Contamination Philosophy: Efficient Space Simulation Chamber Cleaning Techniques

    NASA Technical Reports Server (NTRS)

    Roman, Juan A.; Stitt, George F.; Roman, Felix R.

    1997-01-01

    This paper will provide a general overview of the molecular contamination philosophy of the Space Simulation Test Engineering Section and how the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) space simulation laboratory controls and maintains the cleanliness of all its facilities, thereby, minimizing down time between tests. It will also briefly cover the proper selection and safety precautions needed when using some chemical solvents for wiping, washing, or spraying thermal shrouds when molecular contaminants increase to unacceptable background levels.

  13. Imaging the dust sublimation front of a circumbinary disk

    NASA Astrophysics Data System (ADS)

    Hillen, M.; Kluska, J.; Le Bouquin, J.-B.; Van Winckel, H.; Berger, J.-P.; Kamath, D.; Bujarrabal, V.

    2016-04-01

    Aims: We present the first near-IR milli-arcsecond-scale image of a post-AGB binary that is surrounded by hot circumbinary dust. Methods: A very rich interferometric data set in six spectral channels was acquired of IRAS 08544-4431 with the new RAPID camera on the PIONIER beam combiner at the Very Large Telescope Interferometer (VLTI). A broadband image in the H-band was reconstructed by combining the data of all spectral channels using the SPARCO method. Results: We spatially separate all the building blocks of the IRAS 08544-4431 system in our milliarcsecond-resolution image. Our dissection reveals a dust sublimation front that is strikingly similar to that expected in early-stage protoplanetary disks, as well as an unexpected flux signal of ~4% from the secondary star. The energy output from this companion indicates the presence of a compact circum-companion accretion disk, which is likely the origin of the fast outflow detected in Hα. Conclusions: Our image provides the most detailed view into the heart of a dusty circumstellar disk to date. Our results demonstrate that binary evolution processes and circumstellar disk evolution can be studied in detail in space and over time. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program ID 094.D-0865.

  14. Tracking closely spaced multiple sources via spectral-estimation techniques

    NASA Astrophysics Data System (ADS)

    Gabriel, W. F.

    1982-06-01

    Modern spectral-estimation techniques have achieved a level of performance that attracts interest in applications area such as the tracking of multiple spatial sources. In addition to the original "superresolution' capability, these techniques offer an apparent 'absence of sidelobes' characteristic and some reasonable solutions to the difficult radar coherent-source problem that involves a phase-dependent SNR (signal-to-noise ratio) penalty. This report reviews the situation briefly, and it discusses a few of the techniques that have been found useful, including natural or synthetic doppler shifts, non-Toeplitz forward-backward subaperture-shift processing, and recent eigenvalue/eigenvector analysis algorithms. The techniques are applied to multiple-source situations that include mixtures of coherent and noncoherent sources of unequal strengths, with either an 8-or a 12-element linear-array sampling aperture. The first test case involves the estimation of six sources, two of which are 95% correlated. The second test case involves a tracking-simulation display example of four moving sources: three are -10dB coherent sources 95% correlated, and the other is a strong 20-dB noncoherent source. These test cases demonstrate the remarkable improvements obtained with the recent estimation techniques, and they point to the possibilities for real-world applications.

  15. Development of Backscatter X-Ray Imaging Techniques for Space Vehicle Applications

    NASA Technical Reports Server (NTRS)

    Bartha, Bence B.; Hope, Dale; Vona, Paul; Born, Martin; Corak, Tony

    2009-01-01

    This slide presentation reviews the development of backscatter x ray (BSX) imaging techniques to perform inspection of spacecraft components. The techniques are currently being enhanced to advance Non-Destructive Testing (NDT) methods for future space vehicle applications. The presentation includes an overview of x ray techniques, a description of current BSX applications used on the space shuttle, the development for Constellation applications, and the use of the system for foam applications.

  16. SPIKE: AI scheduling techniques for Hubble Space Telescope

    NASA Astrophysics Data System (ADS)

    Johnston, Mark D.

    1991-09-01

    AI (Artificial Intelligence) scheduling techniques for HST are presented in the form of the viewgraphs. The following subject areas are covered: domain; HST constraint timescales; HTS scheduling; SPIKE overview; SPIKE architecture; constraint representation and reasoning; use of suitability functions by scheduling agent; SPIKE screen example; advantages of suitability function framework; limiting search and constraint propagation; scheduling search; stochastic search; repair methods; implementation; and status.

  17. Technique to Predict Ultraviolet Radiation Embrittlement of Polymers in Space

    NASA Technical Reports Server (NTRS)

    1996-01-01

    In the low-Earth-orbit environment, solar ultraviolet (UV) radiation embrittles polymer materials through bond breaking and crosslinking. This UV embrittlement increases the surface hardness of the polymer. Before the durability of polymer materials in the low- Earth-orbit environment can be predicted, the extent of UV embrittlement needs to be determined. However, traditional techniques for measuring the microhardness of materials cannot be employed to measure changes in the hardness of UV-embrittled surfaces because traditional techniques measure bulk hardness and are not sensitive enough to surface changes. A unique technique was used at the NASA Lewis Research Center to quantify polymer surface damage that had been induced by UV radiation. The technique uses an atomic force microscope (AFM) to measure surface microhardness. An atomic force microscope measures the repulsive forces between the atoms in a microscopic cantilevered tip and the atoms on the surface of a sample. Typically, an atomic force microscope produces a topographic image of a surface by monitoring the movement of the tip over features of the surface. The force applied to the cantilevered tip, and the indention of the tip into the surface, can be measured. The relationship between force and distance of indentation, the quantity force/distance (newtons/meter), provides a measure of the surface hardness. Under identical operating conditions, direct comparisons of surface hardness values can be made.

  18. Sublimation-Condensation of Multiscale Tellurium Structures

    SciTech Connect

    Riley, Brian J.; Johnson, Bradley R.; Schaef, Herbert T.; Sundaram, S. K.

    2013-03-11

    This paper presents a simple technique for making tellurium (Te) nano and microtubes of widely varying dimensions with Multi-Scale Processing (MSP). In this process, the Te metal is placed in a reaction vessel (e.g., borosilicate or fused quartz), the vessel is evacuated, and then sealed under vacuum with a torch. The vessel is heat-treated in a temperature gradient where a portion of the tube that can also contain an additional substrate, is under a decreasing temperature gradient. Scanning and transmission electron microscopies have shown that multifaceted crystalline tubes have been formed extending from nano- up to micron-scale with diameters ranging from 51.2 ± 5.9 to 1042 ± 134 nm between temperatures of 157 and 224 °C, respectively. One-dimensional tubular features are seen at lower temperatures, while three-dimensional features, at the higher temperatures. These features have been characterized with X-ray diffraction and found to be trigonal Te with space group P3121. Our results show that the MSP can adequately be described using a simple Arrhenius equation.

  19. Analysis of space tug operating techniques. Volume 2: Study results

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The design requirements for space tug systems and cost analysis of the refurbishment phases are discussed. The vehicle is an integral propulsion stage using liquid hydrogen and liquid oxygen as propellants and is capable of operating either as a fully or a partially autonomous vehicle. Structural features are an integral liquid hydrogen tank, a liquid oxygen tank, a meteoroid shield, an aft conical docking and structural support ring, and a staged combustion main engine. The vehicle is constructed of major modules for ease of maintenance. Line drawings and block diagrams are included to explain the maintenance requirements for the subsystems.

  20. Titanium Nitride Epitaxy on Tungsten (100) by Sublimation Crystal Growth

    SciTech Connect

    Mercurio, Lisa; Du, Li; Edgar, J H; Kenik, Edward A

    2007-01-01

    Titanium nitride crystals were grown from titanium nitride powder on tungsten by the sublimation-recondensation technique. The bright golden TiN crystals displayed a variety of shapes including cubes, truncated tetrahedrons, truncated octahedrons, and tetrahedrons bounded by (111) and (100) crystal planes. The TiN crystals formed regular, repeated patterns within individual W grains that suggested epitaxy. X-ray diffraction and electron backscattering diffraction revealed that the tungsten foil was highly textured with a preferred foil normal of (100) and confirmed that the TiN particles deposited epitaxially with the orientation TiN(100)/W(100) and TiN[100]/W[110], that is, the unit cells of the TiN crystals were rotated 45{sup o} with respect to the tungsten. Because of its larger coefficient of thermal expansion compared to W, upon cooling from the growth temperature, the TiN crystals were under in-plane tensile strain, causing many of the TiN crystals to crack.

  1. Space shuttle transportation system techniques for user/use development

    NASA Technical Reports Server (NTRS)

    Gripshover, P. J.

    1974-01-01

    The problem of obtaining new uses for the Shuttle Transportation System (STS) was treated in the same way marketing problems are handled by industrial organizations. Techniques used by industry to obtain new ideas and customers were evaluated and analyzed for their relevance to the STS. Marketing barrier-data were used to develop strategy which called for a middleman organization to assist NASA in achieving its objectives. The importance of prompt initiation of the recommended strategy was established.

  2. Analytic and interferometric techniques for the Laser Interferometer Space Antenna

    NASA Astrophysics Data System (ADS)

    Pollack, Scott E.

    The Laser Interferometer Space Antenna (LISA) is being designed to detect and study in detail gravitational waves from sources throughout the Universe such as massive black holes. The conceptual formulation of the LISA space-borne gravitational wave detector is now well developed. The interferometric measurements between the sciencecraft remain one of the most important technological and scientific design areas for the mission. Our work has concentrated on developing the interferometric technologies to create a LISA-like optical signal and to measure the phase of that signal using commercially available instruments. One of the most important goals of this research is to demonstrate the LISA phase timing and phase reconstruction for a LISA-like fringe signal, in the case of a high fringe rate and a low signal level. To this end we have constructed a table-top interferometer which produces LISA-like fringe signals. Over the past few years questions have been raised concerning the use of laser communications links between sciencecraft to transmit phase information crucial to the reduction of laser frequency noise in the LISA science measurement. The concern is that applying medium frequency phase modulations to the laser carrier could compromise the phase stability of the LISA fringe signal. We have modified our table-top interferometer by applying a phase modulation to the laser beam in order to evaluate the effects of such modulations on the LISA science fringe signal. We have demonstrated that the phase resolution of the science signal is not degraded by the presence of medium frequency phase modulations. Each spacecraft in LISA houses a proof mass which follows a geodesic through space. Disturbances that change the proof mass position, momentum, and acceleration will appear in the LISA data stream as additive quadratic functions. These data disturbances inhibit signal extraction and must be removed. Much of our analytical work has been focused on discussing the

  3. Error control techniques for satellite and space communications

    NASA Technical Reports Server (NTRS)

    Costello, Daniel J., Jr.

    1992-01-01

    Worked performed during the reporting period is summarized. Construction of robustly good trellis codes for use with sequential decoding was developed. The robustly good trellis codes provide a much better trade off between free distance and distance profile. The unequal error protection capabilities of convolutional codes was studied. The problem of finding good large constraint length, low rate convolutional codes for deep space applications is investigated. A formula for computing the free distance of 1/n convolutional codes was discovered. Double memory (DM) codes, codes with two memory units per unit bit position, were studied; a search for optimal DM codes is being conducted. An algorithm for constructing convolutional codes from a given quasi-cyclic code was developed. Papers based on the above work are included in the appendix.

  4. An investigation on the mechanism of sublimed DHB matrix on molecular ion yields in SIMS imaging of brain tissue.

    PubMed

    Dowlatshahi Pour, Masoumeh; Malmberg, Per; Ewing, Andrew

    2016-05-01

    We have characterized the use of sublimation to deposit matrix-assisted laser desorption/ionization (MALDI) matrices in secondary ion mass spectrometry (SIMS) analysis, i.e. matrix-enhanced SIMS (ME-SIMS), a common surface modification method to enhance sensitivity for larger molecules and to increase the production of intact molecular ions. We use sublimation to apply a thin layer of a conventional MALDI matrix, 2,5-dihydroxybenzoic acid (DHB), onto rat brain cerebellum tissue to show how this technique can be used to enhance molecular yields in SIMS while still retaining a lateral resolution around 2 μm and also to investigate the mechanism of this enhancement. The results here illustrate that cholesterol, which is a dominant lipid species in the brain, is decreased on the tissue surface after deposition of matrix, particularly in white matter. The decrease of cholesterol is followed by an increased ion yield of several other lipid species. Depth profiling of the sublimed rat brain reveals that the lipid species are de facto extracted by the DHB matrix and concentrated in the top most layers of the sublimed matrix. This extraction/concentration of lipids directly leads to an increase of higher mass lipid ion yield. It is also possible that the decrease of cholesterol decreases the potential suppression of ion yield caused by cholesterol migration to the tissue surface. This result provides us with significant insights into the possible mechanisms involved when using sublimation to deposit this matrix in ME-SIMS. Graphical Abstract Schematic representation of the enhancement on the molecular ion yields in SIMS by deposition of DHB matrix on the brain tissue using sublimation. PMID:26922337

  5. A study of trends and techniques for space base electronics

    NASA Technical Reports Server (NTRS)

    Trotter, J. D.; Wade, T. E.; Gassaway, J. D.; Mahmood, Q.

    1978-01-01

    A sputtering system was developed to deposit aluminum and aluminum alloys by the dc sputtering technique. This system is designed for a high level of cleanliness and for monitoring the deposition parameters during film preparation. This system is now ready for studying the deposition and annealing parameters upon double-level metal preparation. A technique recently applied for semiconductor analysis, the finite element method, was studied for use in the computer modeling of two dimensional MOS transistor structures. It was concluded that the method has not been sufficiently well developed for confident use at this time. An algorithm was developed for confident use at this time. An algorithm was developed for implementing a computer study which is based upon the finite difference method. The program which was developed was modified and used to calculate redistribution data for boron and phosphorous which had been predeposited by ion implantation with range and straggle conditions. Data were generated for 111 oriented SOS films with redistribution in N2, dry O2 and steam ambients.

  6. Space simulation techniques and facilities for SAX STM test campaign

    NASA Technical Reports Server (NTRS)

    Giordano, Pietro; Raimondo, Giacomo; Messidoro, Piero

    1994-01-01

    SAX is a satellite for X-Ray astronomy. It is a major element of the overall basic Science Program of the Italian Space Agency (ASI) and is being developed with the contribution of the Netherlands Agency for Aerospace Programs (NIVR). The scientific objectives of SAX are to carry out systematic and comprehensive observations of celestial X-Ray sources over the 0.1 - 300 KeV energy range with special emphasis on spectral and timing measurements. The satellite will also monitor the X-Ray sky to investigate long-term source variability and to permit localization and study of X-Ray transients. Alenia Spazio is developing the satellite that is intended for launch in the second half of 1995 in a low, near-equatorial Earth orbit. At system level a Structural Thermal Model (STM) has been conceived to verify the environmental requirements by validating the mechanical and thermal analytical models and qualifying satellite structure and thermal control. In particular, the following tests have been carried out in Alenia Spazio, CEA/CESTA and ESTEC facilities: Modal Survey, Centrifuge, Acoustic, Sinusoidal/Random Vibration and Thermal Balance. The paper, after a short introduction of the SAX satellite, summarizes the environmental qualification program performed on the SAX STM. It presents test objectives, methodologies and relevant test configurations. Peculiar aspects of the test campaign are highlighted. Problems encountered and solutions adopted in performing the tests are described as well. Furthermore, test results are presented and assessed.

  7. Cryogenic techniques for large superconducting magnets in space

    NASA Technical Reports Server (NTRS)

    Green, M. A.

    1989-01-01

    A large superconducting magnet is proposed for use in a particle astrophysics experiment, ASTROMAG, which is to be mounted on the United States Space Station. This experiment will have a two-coil superconducting magnet with coils which are 1.3 to 1.7 meters in diameter. The two-coil magnet will have zero net magnetic dipole moment. The field 15 meters from the magnet will approach earth's field in low earth orbit. The issue of high Tc superconductor will be discussed in the paper. The reasons for using conventional niobium-titanium superconductor cooled with superfluid helium will be presented. Since the purpose of the magnet is to do particle astrophysics, the superconducting coils must be located close to the charged particle detectors. The trade off between the particle physics possible and the cryogenic insulation around the coils is discussed. As a result, the ASTROMAG magnet coils will be operated outside of the superfluid helium storage tank. The fountain effect pumping system which will be used to cool the coil is described in the report. Two methods for extending the operating life of the superfluid helium dewar are discussed. These include: operation with a third shield cooled to 90 K with a sterling cycle cryocooler, and a hybrid cryogenic system where there are three hydrogen-cooled shields and cryostat support heat intercept points.

  8. Interferometric Techniques for Gravitational Wave Detection in Space

    NASA Technical Reports Server (NTRS)

    Stebbins, Robin T; Bender, Peter L.

    2000-01-01

    The Laser Interferometer Space Antenna (LISA) mission will detect gravitational waves from galactic and extragalactic sources, most importantly those involving supermassive black holes. The primary goal of this project is to investigate stability and robustness issues associated with LISA interferometry. We specifically propose to study systematic errors arising from: optical misalignments, optical surface errors, thermal effects and pointing tolerances. This report covers the first fiscal year of the grant, from January 1st to December 31st 1999. We have employed an optical modeling tool to evaluate the effect of misplaced and misaligned optical components. Preliminary results seem to indicate that positional tolerances of one micron and angular tolerances of 0.6 millirad produce no significant effect on the achievable contrast of the interference pattern. This report also outlines research plans for the second fiscal year of the grant, from January 1st to December 31st 2000. Since the work under NAG5-6880 has gone more rapidly than projected, our test bed interferometer is operational, and can be used for measurements of effects that cause beam motion. Hence, we will design, build and characterize a sensor for measuring beam motion, and then install it. We are also planning a differential wavefront sensor based on a quadrant photodiode as a first generation sensor.

  9. Action Research to Improve the Learning Space for Diagnostic Techniques.

    PubMed

    Ariel, Ellen; Owens, Leigh

    2015-12-01

    The module described and evaluated here was created in response to perceived learning difficulties in diagnostic test design and interpretation for students in third-year Clinical Microbiology. Previously, the activities in lectures and laboratory classes in the module fell into the lower cognitive operations of "knowledge" and "understanding." The new approach was to exchange part of the traditional activities with elements of interactive learning, where students had the opportunity to engage in deep learning using a variety of learning styles. The effectiveness of the new curriculum was assessed by means of on-course student assessment throughout the module, a final exam, an anonymous questionnaire on student evaluation of the different activities and a focus group of volunteers. Although the new curriculum enabled a major part of the student cohort to achieve higher pass grades (p < 0.001), it did not meet the requirements of the weaker students, and the proportion of the students failing the module remained at 34%. The action research applied here provided a number of valuable suggestions from students on how to improve future curricula from their perspective. Most importantly, an interactive online program that facilitated flexibility in the learning space for the different reagents and their interaction in diagnostic tests was proposed. The methods applied to improve and assess a curriculum refresh by involving students as partners in the process, as well as the outcomes, are discussed. Journal of Microbiology & Biology Education. PMID:26753024

  10. Error control techniques for satellite and space communications

    NASA Technical Reports Server (NTRS)

    Costello, D. J., Jr.

    1986-01-01

    High rate concatenated coding systems with trellis inner codes and Reed-Solomon (RS) outer codes for application in satellite communication systems are considered. Two types of inner codes are studied: high rate punctured binary convolutional codes which result in overall effective information rates between 1/2 and 1 bit per channel use; and bandwidth efficient signal space trellis codes which can achieve overall effective information rates greater than 1 bit per channel use. Channel capacity calculations with and without side information performed for the concatenated coding system. Concatenated coding schemes are investigated. In Scheme 1, the inner code is decoded with the Viterbi algorithm and the outer RS code performs error-correction only (decoding without side information). In scheme 2, the inner code is decoded with a modified Viterbi algorithm which produces reliability information along with the decoded output. In this algorithm, path metrics are used to estimate the entire information sequence, while branch metrics are used to provide the reliability information on the decoded sequence. This information is used to erase unreliable bits in the decoded output. An errors-and-erasures RS decoder is then used for the outer code. These two schemes are proposed for use on NASA satellite channels. Results indicate that high system reliability can be achieved with little or no bandwidth expansion.

  11. Sublimation of a crystal slowed by sorption of foreign molecules from a gaseous medium

    NASA Astrophysics Data System (ADS)

    Bochkarev, A. A.; Polyakova, V. I.

    2014-07-01

    Numerical simulation of the sublimation of the surface of an ice crystal has shown that the presence of a non-condensable gas substantially reduces the sublimation rate. It has been found that the slowing of the sublimation due to the adsorption of gas molecules on the crystal surface that fill the vacancies during sublimation prevents the formation of vacancy islands on the surface of the crystal required for evaporation of the surface molecular layer. The available results of studies that explain the slowing of the sublimation by the presence of a diffusion layer formed in the vapor medium near the sublimating surface are supplemented with new data showing that molecular processes on the crystal surface play an equally important role as the diffusion layer. Cases have been found where crystal sublimation is accelerated by the sorption of gas molecules. The obtained results refining the theory of sublimation can be used to develop methods for controlling sublimation.

  12. Spacing Techniques in Second Language Vocabulary Acquisition: Short-Term Gains vs. Long-Term Memory

    ERIC Educational Resources Information Center

    Schuetze, Ulf

    2015-01-01

    This article reports the results of two experiments using the spacing technique (Leitner, 1972; Landauer & Bjork, 1978) in second language vocabulary acquisition. In the past, studies in this area have produced mixed results attempting to differentiate between massed, uniform and expanded intervals of spacing (Balota, Duchek, & Logan,…

  13. Sublimating grains in the coma of new comets originating from the Oort Cloud

    NASA Astrophysics Data System (ADS)

    Faggi, S.; Tozzi, G.; Brucato, J.; Bruni, I.; Licandro, J.; Mazzotta Epifani, E.; Meech, K.; Mottola, S.

    2014-07-01

    It is expected that a billion of years of space weathering (see, e.g., Kanuchova et al., 2012, Icarus, 221, 12) produces a crust of organic matter that will be released when a comet enters, for the first time, in the inner Solar System. When approaching to the Sun, a comet is at heliocentric distances r_h greater than 3 au, the sublimation of CO and CO_2 is the main source of cometary activity. At shorter distances, the sublimation of water becomes the most important mechanism of activity. The gases escaping from the nucleus cause drag for the coma grains that can be refractory dust (silicates, carbon), water ice, and/or organic ices. Oort comets at their first passage in the inner Solar System, should produce an halo of organic or water ice particles. Recently, our group started to monitor new, inbound, bright Oort comets (C/2011 F1, C/2012 S1, C/2012 K1, C/2013 V5, C/2012 F3) to search for these grains. The method consists of detecting the cloud of sublimating grains in the inner coma by using the ΣAf(ρ) function (Tozzi et al., 2007, A&A, 476, 979). However, this over-population of grains, beside the sublimation, can be also due to short-time activity (outburst) or too large grains expanding at very slow velocity, as it has been found in comet 67P/C-G (Tozzi et al., 2011, A&A, 531, 54). To discriminate between the phenomena, it is necessary to monitor the comet both at short timescales for the outbursts (by repeating the observations after a few nights), and in a longer term (weeks to months). If the cloud does not expand with decreasing heliocentric distance, there is a high probability that organic and/or water-ice grains are present. We can discriminate between organic and water-ice grains by measuring their color and spectra. In this work, we will present the results obtained from the observations of C/2011 F1 (LINEAR) and C/2012 S1 (ISON). The comparison between data and theoretical simulations, obtained with a simple model assuming sublimating grains

  14. Alumina Paste Sublimation Suppression Barrier for Thermoelectric Device

    NASA Technical Reports Server (NTRS)

    Paik, Jong-Ah (Inventor); Caillat, Thierry (Inventor)

    2014-01-01

    Alumina as a sublimation suppression barrier for a Zintl thermoelectric material in a thermoelectric power generation device operating at high temperature, e.g. at or above 1000K, is disclosed. The Zintl thermoelectric material may comprise Yb.sub.14MnSb.sub.11. The alumina may be applied as an adhesive paste dried and cured on a substantially oxide free surface of the Zintl thermoelectric material and polished to a final thickness. The sublimation suppression barrier may be finalized by baking out the alumina layer on the Zintl thermoelectric material until it becomes substantially clogged with ytterbia.

  15. Contactless prompt tumbling rebound of drops from a sublimating slope

    NASA Astrophysics Data System (ADS)

    Antonini, Carlo; Jung, Stefan; Wetzel, Andreas; Heer, Emmanuel; Schoch, Philippe; Moqaddam, Ali Mazloomi; Chikatamarla, Shyam S.; Karlin, Ilya; Marengo, Marco; Poulikakos, Dimos

    2016-05-01

    We have uncovered a drop rebound regime, characteristic of highly viscous liquids impacting tilted sublimating surfaces. Here the drops, rather than showing a slide, spread, recoil, and rebound behavior, exhibit a prompt tumbling rebound. As a result, glycerol surprisingly rebounds faster than three orders of magnitude less viscous water. When a viscous drop impacts a sublimating surface, part of its initial linear momentum is converted into angular momentum: Lattice Boltzmann simulations confirmed that tumbling owes its appearance to the rapid transition of the internal angular velocity prior to rebound to a constant value, as in a tumbling solid body.

  16. Multi-technique TRF realization with Jason-2 as a space tie

    NASA Astrophysics Data System (ADS)

    Zoulida, Myriam; Pollet, Arnaud; Rebischung, Paul; Coulot, David; Biancale, Richard

    2016-04-01

    In the present approach used to produce the International Terrestrial Reference Frame (ITRF), observations of the different space geodetic techniques are reduced in independent analyses. The only mean to tie the resulting technique-specific frames into a homogeneous combined frame is then to use local topometric ties between stations of different techniques co-located at the same observatory. However, inconsistencies between these local ties and space geodesy estimates of the station positions are today a major limiting factor of the ITRF accuracy. An alternative way of tying the different space geodetic techniques together is through the use of multitechnique satellites equipped with instruments of more than one technique. But the main challenge of using such a satellite as an inter-technique link resides in the accurate knowledge (or estimation) of the vectors between the satellite's center of mass and the reference points of its different instruments (i.e. space ties). In this study, the results from multi-technique (GPS+SLR+DORIS) analyses involving the Jason-2 satellite are presented and compared to the results from traditional single-technique analyses. We assess in particular the effect of simultaneously processing the observations of the three techniques with Jason-2 as inter-technique link on the resolution of the GPS phase ambiguities, on the estimation of the GPS and Jason-2 satellite orbits and on the estimation of the ground station positions. Moreover, results of the estimation of the Jason-2 space ties will be presented, in order to assess the quality of the presently available values.

  17. Simulation verification techniques study: Simulation performance validation techniques document. [for the space shuttle system

    NASA Technical Reports Server (NTRS)

    Duncan, L. M.; Reddell, J. P.; Schoonmaker, P. B.

    1975-01-01

    Techniques and support software for the efficient performance of simulation validation are discussed. Overall validation software structure, the performance of validation at various levels of simulation integration, guidelines for check case formulation, methods for real time acquisition and formatting of data from an all up operational simulator, and methods and criteria for comparison and evaluation of simulation data are included. Vehicle subsystems modules, module integration, special test requirements, and reference data formats are also described.

  18. Sublimation of Ices Containing Organics and/or Minerals and Implications for Icy Bodies Surface Structure and Spectral Properties

    NASA Astrophysics Data System (ADS)

    Poch, O.; Pommerol, A.; Jost, B.; Yoldi, Z.; Carrasco, N.; Szopa, C.; Thomas, N.

    2015-12-01

    The surfaces of many objects in the Solar System comprise substantial quantities of water ice either in pure form or mixed with minerals and/or organic molecules. Sublimation is a process responsible for shaping and changing the reflectance properties of these objects. We present laboratory data on the evolution of the structure and the visible and near-infrared spectral reflectance of icy surfaces made of mixtures of water ice and non-volatile components (complex organic matter and silicates), as they undergo sublimation of the water ice under low temperature and pressure conditions (Poch et al., under review). We prepared icy surfaces which are potential analogues of ices found on comets, icy satellites or trans-neptunian objects (TNOs). The experiments were carried out in the SCITEAS simulation setup recently built as part of the Laboratory for Outflow Studies of Sublimating Materials (LOSSy) at the University of Bern (Pommerol et al., 2015a). As the water ice sublimated, we observed in situ the formation of a sublimation lag deposit, or sublimation mantle, made of the non-volatiles at the top of the samples. The texture (porosity, internal cohesiveness etc.), the activity (outbursts and ejection of mantle fragments) and the spectro-photometric properties of this mantle are found to differ strongly depending on the chemical nature of the non-volatiles, the size of their particles, the way they are mixed with the volatile component and the dust/ice mass ratio. The results also indicate how the band depths of the sub-surface water ice evolve during the build-up of the sublimation mantle. These data provide useful references for interpreting remote-sensing observations of Rosetta (see Pommerol et al., 2015b), and also New Horizons. Poch, O., et al., under review in IcarusPommerol, A., et al., 2015a, Planet. Space Sci. 109-110, 106-122. http://dx.doi.org/10.1016/j.pss.2015.02.004Pommerol, A., et al., 2015b, Astronomy and Astrophysics, in press. http://dx.doi.org/10.1051/0004-6361/201525977

  19. Modeling the development of martian sublimation thermokarst landforms

    USGS Publications Warehouse

    Dundas, Colin M.; Byrne, Shane; McEwen, Alfred S.

    2015-01-01

    Sublimation-thermokarst landforms result from collapse of the surface when ice is lost from the subsurface. On Mars, scalloped landforms with scales of decameters to kilometers are observed in the mid-latitudes and considered likely thermokarst features. We describe a landscape evolution model that couples diffusive mass movement and subsurface ice loss due to sublimation. Over periods of tens of thousands of Mars years under conditions similar to the present, the model produces scallop-like features similar to those on the Martian surface, starting from much smaller initial disturbances. The model also indicates crater expansion when impacts occur in surfaces underlain by excess ice to some depth, with morphologies similar to observed landforms on the Martian northern plains. In order to produce these landforms by sublimation, substantial quantities of excess ice are required, at least comparable to the vertical extent of the landform, and such ice must remain in adjacent terrain to support the non-deflated surface. We suggest that Martian thermokarst features are consistent with formation by sublimation, without melting, and that significant thicknesses of very clean excess ice (up to many tens of meters, the depth of some scalloped depressions) are locally present in the Martian mid-latitudes. Climate conditions leading to melting at significant depth are not required.

  20. Modeling the development of martian sublimation thermokarst landforms

    NASA Astrophysics Data System (ADS)

    Dundas, Colin M.; Byrne, Shane; McEwen, Alfred S.

    2015-12-01

    Sublimation-thermokarst landforms result from collapse of the surface when ice is lost from the subsurface. On Mars, scalloped landforms with scales of decameters to kilometers are observed in the mid-latitudes and considered likely thermokarst features. We describe a landscape evolution model that couples diffusive mass movement and subsurface ice loss due to sublimation. Over periods of tens of thousands of Mars years under conditions similar to the present, the model produces scallop-like features similar to those on the martian surface, starting from much smaller initial disturbances. The model also indicates crater expansion when impacts occur in surfaces underlain by excess ice to some depth, with morphologies similar to observed landforms on the martian northern plains. In order to produce these landforms by sublimation, substantial quantities of excess ice are required, at least comparable to the vertical extent of the landform, and such ice must remain in adjacent terrain to support the non-deflated surface. We suggest that martian thermokarst features are consistent with formation by sublimation, without melting, and that significant thicknesses of very clean excess ice (up to many tens of meters, the depth of some scalloped depressions) are locally present in the martian mid-latitudes. Climate conditions leading to melting at significant depth are not required.

  1. Literary Study, Measurement, and the Sublime: Disciplinary Assessment

    ERIC Educational Resources Information Center

    Heiland, Donna, Ed.; Rosenthal, Laura J., Ed.

    2011-01-01

    This collection of essays, "Literary Study, Measurement, and the Sublime: Disciplinary Assessment," edited by Donna Heiland and Laura J. Rosenthal, represents an important new venture in the Foundation's communication program. The book is the product of many authors, including the editors, both of whom have written essays for it. But it is the…

  2. Isotopic Fractionation of Water-Ice from Sublimation

    NASA Astrophysics Data System (ADS)

    Christensen, E.; Boyer, C.; Park, M.; Gormally, J.; Benitez, E.; Dominguez, G.

    2015-12-01

    Elizabeth Christensen, Charisa Boyer, Manesseh Park, Ezra Benitez, Gerardo Dominguez Understanding the multi-isotopic fractionation of water-ice that results from its sublimation may be important for understanding the isotopic composition of cometary ices. Here we describe an experimental setup whose purpose is to understand the effects of various astrophysical processes on the δD and δ18O and δ17O composition of water-ices. Our setup consists of an ultrahigh vacuum (UHV) chamber with oil free pumping, a closed cycle He cryostat to achieve low temperatures (capable of reaching 6K), and a vacuum line connected to the chamber via a UHV feed-through. Water isotopologues H216O, H218O, H217O, and HD16O samples can be measured after sublimation of water-ice with a cavity ring-down spectrometer (Picarro L2120-i) that is connected to the vacuum line. To perform these experiments, ambient water vapor was introduced into, frozen, and purified inside the UHV chamber (T< 150 K). Water-ice samples were sublimated for varying amounts of time to collect various fractions of the original reservoir. We will present the first results on the oxygen and deuterium isotopic fractionation of water-ice sublimation and discuss their implications for interpreting the isotopic compositions of cometary ices.

  3. The Digital Sublime: Lessons from Kelli Connell's "Double Life"

    ERIC Educational Resources Information Center

    Huang, Yi-hui

    2012-01-01

    The digital sublime refers to digital-composite photography that presents "the existence of something unpresentable" and that renders a matchless look a sophisticated fabrication, a perfect and clean composition, a maximum color saturation, a multiple-point perspective, and stunning or newfangled content. Abandoning the traditional one-shot mode…

  4. System for NO reduction using sublimation of cyanuric acid

    DOEpatents

    Perry, R.A.

    1989-01-24

    An arrangement for reducing the NO content of a gas stream comprises contacting the gas stream with HNCO at a temperature effective for heat induced decomposition of HNCO and for resultant lowering of the NO content of the gas stream. Preferably, the HNCO is generated by sublimation of cyanuric acid. 1 fig.

  5. System for NO reduction using sublimation of cyanuric acid

    DOEpatents

    Perry, Robert A.

    1989-01-01

    An arrangement for reducing the NO content of a gas stream comprises contacting the gas stream with HNCO at a temperature effective for heat induced decomposition of HNCO and for resultant lowering of the NO content of the gas stream. Preferably, the HNCO is generated by sublimation of cyanuric acid.

  6. Alumina Paste Layer as a Sublimation Suppression Barrier for Yb14MnSb11

    NASA Technical Reports Server (NTRS)

    Paik, Jong-Ah; Caillat, Thierry

    2010-01-01

    Sublimation is a major cause of degradation of thermoelectric power generation systems. Most thermoelectric materials tend to have peak values at the temperature where sublimation occurs. A sublimation barrier is needed that is stable at operating temperatures, inert against thermoelectric materials, and able to withstand thermal cycling stress. A porous alumina paste layer is suitable as a sublimation barrier for Yb14MnSb11. It can accommodate stress generated by the thermal expansion discrepancy between the suppression layer and thermoelectric materials. Sublimation suppression is achieved by filling pores naturally with YbO2, a natural byproduct of sublimation. YbO2 generated during the sublimation of Yb14MnSb11 fills the porous structure of the alumina paste, causing sublimation to decrease with time as the pores become filled.

  7. Advances in sublimation studies for particles of explosives

    NASA Astrophysics Data System (ADS)

    Furstenberg, Robert; Nguyen, Viet; Fischer, Thomas; Abrishami, Tara; Papantonakis, Michael; Kendziora, Chris; Mott, David R.; McGill, R. Andrew

    2015-05-01

    When handling explosives, or related surfaces, the hands routinely become contaminated with particles of explosives and related materials. Subsequent contact with a solid surface results in particle crushing and deposition. These particles provide an evidentiary trail which is useful for security applications. As such, the opto-physico-chemical characteristics of these particles are critical to trace explosives detection applications in DOD or DHS arenas. As the persistence of these particles is vital to their forensic exploitation, it is important to understand which factors influence their persistence. The longevity or stability of explosives particles on a substrate is a function of several environmental parameters or particle properties including: Vapor pressure, particle geometry, airflow, particle field size, substrate topography, humidity, reactivity, adlayers, admixtures, particle areal density, and temperature. In this work we deposited particles of 2,4-dinitrotoluene on standard microscopy glass slides by particle sieving and studied their sublimation as a function of airflow velocity, areal particle density and particle field size. Analysis of 2D microscopic images was used to compute and track particle size and geometrical characteristics. The humidity, temperature and substrate type were kept constant for each experiment. A custom airflow cell, using standard microscopy glass slide, allowed in-situ photomicroscopy. Areal particle densities and airflow velocities were selected to provide relevant loadings and flow velocities for a range of potential applications. For a chemical of interest, we define the radial sublimation velocity (RSV) for the equivalent sphere of a particle as the parameter to characterize the sublimation rate. The RSV is a useful parameter because it is independent of particle size. The sublimation rate for an ensemble of particles was found to significantly depend on airflow velocity, the areal density of the particles, and the

  8. Novel techniques for the thermal management of space-based, high-power microwave tubes

    NASA Astrophysics Data System (ADS)

    Rose, M. F.; Hyder, Anthony K.; Askew, R. F.; Chow, L.; Gilmour, A. S., Jr.; Faghri, A.

    1991-10-01

    This work is based in part on a study by the authors to determine the applicability of several concepts to the cooling of high-power linear microwave tubes operating in space under a variety of conditions. The authors focus on: direct radiation to space, beam exit to space, thermal storage, secondary coolant loops/heat pipes, and the use of supercritical hydrogen as a coolant with subsequent ejection to space. Each of these techniques is evaluated within the framework of a neutral particle beam weapons system or other limited duty cycle device which might lay dormant for long periods of time, come to life, and function reliably for a specified time. System impact for each technique is estimated in terms of impact on weight, volume, spacecraft interaction, and ease of implementation.

  9. Relationship between molecular descriptors and the enthalpies of sublimation of natural amino acids

    NASA Astrophysics Data System (ADS)

    Badelin, V. G.; Tyunina, V. V.; Girichev, G. V.; Tyunina, E. Yu.

    2016-07-01

    A multiparameter correlation between the enthalpies of sublimation and molecular descriptors of natural amino acids is proposed, based on generalized experimental and literature data on the heat effects of sublimation. The contributions from Van der Waals interactions, hydrogen bond formation, and electrostatic effects into enthalpy of sublimation has been evaluated using regression coefficients.

  10. Sublimation-driven erosion on Hyperion: Topographic analysis and landform simulation model tests

    NASA Astrophysics Data System (ADS)

    Howard, Alan D.; Moore, Jeffrey M.; Schenk, Paul M.; White, Oliver L.; Spencer, John

    2012-07-01

    The unique appearance of Hyperion can be explained in part by the loss to space of ballistic ejecta during impact events, as was proposed by Thomas et al. (Thomas, P.C. et al. [2007a]. Icarus 190, 573-584). We conclude that such loss is a partial explanation, accounting for the lack of appreciable intercrater plains on a saturation-cratered surface. In order to create the smooth surfaces and the reticulate, honeycomb pattern of narrow divides between old craters, appreciable subsequent modification of crater morphology must occur through mass-wasting processes accompanied by sublimation, probably facilitated by the loss of CO2 as a component of the relief-supporting matrix of the bedrock. During early stages of crater degradation, steep, crenulate bedrock slopes occupy the upper crater walls with abrupt transitions downslope onto smooth slopes near the angle of repose mantled by mass wasting debris, as can be seen within young craters. Long-continued mass wasting eventually results in slopes totally mantled with particulate debris. This mass wasting effectively destroys small craters, at least in part accounting for the paucity of sub-kilometer craters on Hyperion. Surface temperatures measured by Cassini CIRS range from 58 K to 127 K and imply a surface thermal inertia of 11 ± 2 J m-2 K-1 s-1/2 and bolometric albedo ranging from 0.05 to 0.33. Resulting H2O sublimation rates are only tens of cm per billion years for most of the surface, so the evolution of the observed landforms is likely to require sublimation of more volatile species such as CO2.

  11. Piezoelectric crystal microbalance measurements of enthalpy of sublimation of C2-C9 dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Dirri, F.; Palomba, E.; Longobardo, A.; Zampetti, E.

    2015-07-01

    We present here a novel experimental setup able to measure the enthalpy of sublimation of a given compound by means of Piezoelectric Crystal Microbalances (PCM). This experiment was performed in the TG-Lab facility in IAPS-INAF, dedicated to the development of TGA sensors for space measurements, such as detection of organic and non-organic volatile species and refractory materials in planetary environments. In order to study physical-chemical processes concerning the Volatile Organic Compounds (VOC) present in atmospheric environments, the setup has been tested on Dicarboxylic acids. Acids with low molecular weight are among the components of organic fraction of particulate matter in the atmosphere, coming from different sources (biogenic and anthropogenic). Considering their relative abundance, it is useful to consider Dicarboxylic acid as "markers" to define the biogenic or anthropogenic origin of the aerosol, thus obtaining some information of the emission sources. In this work, a temperature controlled effusion cell was used to sublimate VOC, creating a molecular flux that was collimated onto a cold PCM. The VOC re-condensed onto the PCM quartz crystal allowing the determination of the deposition rate. From the measurements of deposition rates, it was possible to infer the enthalpy of sublimation of Adipic acid, i.e. Δ Hsub: 141.6 ± 0.8 kJ mol-1, Succinic acid, i.e. 113.3 ± 1.3 kJ mol-1, Oxalic acid, i.e. 62.5 ± 3.1 kJ mol-1 and Azelaic acid, i.e. 124.2 ± 1.2 kJ mol-1 (weight average values). The results obtained are in very good agreement with literature within 10 % for the Adipic, Succinic and Oxalic acid.

  12. Piezoelectric crystal microbalance measurements of enthalpy of sublimation of C2-C9 dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Dirri, F.; Palomba, E.; Longobardo, A.; Zampetti, E.

    2016-02-01

    We present here a novel experimental set-up that is able to measure the enthalpy of sublimation of a given compound by means of piezoelectric crystal microbalances (PCMs). The PCM sensors have already been used for space measurements, such as for the detection of organic and non-organic volatile species and refractory materials in planetary environments. In Earth atmospherics applications, PCMs can be also used to obtain some physical-chemical processes concerning the volatile organic compounds (VOCs) present in atmospheric environments. The experimental set-up has been developed and tested on dicarboxylic acids. In this work, a temperature-controlled effusion cell was used to sublimate VOC, creating a molecular flux that was collimated onto a cold PCM. The VOC recondensed onto the PCM quartz crystal, allowing the determination of the deposition rate. From the measurements of deposition rates, it has been possible to infer the enthalpy of sublimation of adipic acid, i.e. ΔHsub : 141.6 ± 0.8 kJ mol-1, succinic acid, i.e. 113.3 ± 1.3 kJ mol-1, oxalic acid, i.e. 62.5 ± 3.1 kJ mol-1, and azelaic acid, i.e. 124.2 ± 1.2 kJ mol-1. The results obtained show an accuracy of 1 % for succinic, adipic, and azelaic acid and within 5 % for oxalic acid and are in very good agreement with previous works (within 6 % for adipic, succinic, and oxalic acid and within 11 % or larger for azelaic acid).

  13. COMPARISON OF MEASUREMENT TECHNIQUES FOR QUANTIFYING SELECTED ORGANIC EMISSIONS FROM KEROSENE SPACE HEATERS

    EPA Science Inventory

    The report goes results of (1) a comparison the hood and chamber techniques for quantifying pollutant emission rates from unvented combustion appliances, and (2) an assessment of the semivolatile and nonvolatile organic-compound emissions from unvented kerosene space heaters. In ...

  14. Fundamental concepts of structural loading and load relief techniques for the space shuttle

    NASA Technical Reports Server (NTRS)

    Ryan, R. S.; Mowery, D. K.; Winder, S. W.

    1972-01-01

    The prediction of flight loads and their potential reduction, using various control system logics for the space shuttle vehicles, is discussed. Some factors not found on previous launch vehicles that increase the complexity are large lifting surfaces, unsymmetrical structure, unsymmetrical aerodynamics, trajectory control system coupling, and large aeroelastic effects. These load-producing factors and load-reducing techniques are analyzed.

  15. Analysis of space tug operating techniques supplemental report (study 2.4)

    NASA Technical Reports Server (NTRS)

    1972-01-01

    An analysis of space tug operating techniques is presented. The subjects discussed are: (1) sustaining engineering requirements, (2) off-site facility requirements, (3) evaluation of tug checkout alternatives, and (4) spares provisioning. Tables of data are included to clarify the written presentation.

  16. Space shuttle earth orbital rendezvous targeting techniques for near circular target satellite orbits

    NASA Technical Reports Server (NTRS)

    Deaton, A. W.

    1972-01-01

    The targeting techniques are developed which are required to determine the guidance reference release time of the space shuttle navigation system, the orbital insertion targeting values, and a time line of orbital maneuvers. An extension is made for rendezvous with a target satellite in an elliptical orbit.

  17. Nondestructive Inspection Techniques for Friction Stir Weld Verification on the Space Shuttle External Tank

    NASA Technical Reports Server (NTRS)

    Suits, Michael W.; Leak, Jeffery; Bryson, Craig

    2003-01-01

    Friction Stir Welding (FSW) has gained wide acceptance as a reliable joining process for aerospace hardware as witnessed by its recent incorporation into the Delta Launch vehicle cryotanks. This paper describes the development of nondestructive evaluation methods and techniques used to verify the FSW process for NASA's Space Shuttle.

  18. Sublimator Driven Coldplate Engineering Development Unit Test Results

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik B.; Stephan, Ryan A.; Leimkuehler, Thomas O.

    2010-01-01

    The Sublimator Driven Coldplate (SDC) is a unique piece of thermal control hardware that has several advantages over a traditional thermal control scheme. The principal advantage is the possible elimination of a pumped fluid loop, potentially increasing reliability and reducing complexity while saving both mass and power. Because the SDC requires a consumable feedwater, it can only be used for short mission durations. Additionally, the SDC is ideal for a vehicle with small transport distances and low heat rejection requirements. An SDC Engineering Development Unit was designed and fabricated. Performance tests were performed in a vacuum chamber to quantify and assess the performance of the SDC. The test data was then used to develop correlated thermal math models. Nonetheless, an Integrated Sublimator Driven Coldplate (ISDC) concept is being developed. The ISDC couples a coolant loop with the previously described SDC hardware. This combination allows the SDC to be used as a traditional coldplate during long mission phases and provides for dissimilar system redundancy

  19. Robust Magnetic Properties of a Sublimable Single-Molecule Magnet.

    PubMed

    Kiefl, Evan; Mannini, Matteo; Bernot, Kevin; Yi, Xiaohui; Amato, Alex; Leviant, Tom; Magnani, Agnese; Prokscha, Thomas; Suter, Andreas; Sessoli, Roberta; Salman, Zaher

    2016-06-28

    The organization of single-molecule magnets (SMMs) on surfaces via thermal sublimation is a prerequisite for the development of future devices for spintronics exploiting the richness of properties offered by these magnetic molecules. However, a change in the SMM properties due to the interaction with specific surfaces is usually observed. Here we present a rare example of an SMM system that can be thermally sublimated on gold surfaces while maintaining its intact chemical structure and magnetic properties. Muon spin relaxation and ac susceptibility measurements are used to demonstrate that, unlike other SMMs, the magnetic properties of this system in thin films are very similar to those in the bulk, throughout the full volume of the film, including regions near the metal and vacuum interfaces. These results exhibit the robustness of chemical and magnetic properties of this complex and provide important clues for the development of nanostructures based on SMMs. PMID:27139335

  20. Trust: the sublime duty in health care leadership.

    PubMed

    Piper, Llewellyn E

    2010-01-01

    Trust is the essence of human social existence. From the moment of birth, trust is the basic component in any human relationship and interaction. Trust is the Holy Grail for human confidence in others. From human survival to organizational survival, trust is the primordial bond. No organization is more dependent on trust than health care. This article views trust as the most basic fundamental quality for leadership. Trust is a sublime duty of a leader and the leadership of an organization. Leadership sets the culture of trust. Trust is the one quality that is essential for guiding an organization toward serving others. This article addresses trust from many perspectives. Trust is viewed from our subordinates, our peers, our superiors, and the public we serve. This article postulates how trust in an organization is the sublime duty of leadership that unites all human understanding and without it destroys all human relationships. PMID:20145465

  1. Sublimator Driven Coldplate Engineering Development Unit Test Results and Development of Second Generation SDC

    NASA Technical Reports Server (NTRS)

    Stephan, Ryan A.; Sheth, Rubik B.

    2009-01-01

    The Sublimator Driven Coldplate (SDC) is a unique piece of thermal control hardware that has several advantages over a traditional thermal control scheme. The principal advantage is the possible elimination of a pumped fluid loop, potentially increasing reliability and reducing complexity while saving both mass and power. Furthermore, the Integrated Sublimator Driven Coldplate (ISDC) concept couples a coolant loop with the previously described SDC hardware. This combination allows the SDC to be used as a traditional coldplate during long mission phases. The previously developed SDC technology cannot be used for long mission phases due to the fact that it requires a consumable feedwater for heat rejection. Adding a coolant loop also provides for dissimilar redundancy on the Altair Lander ascent module thermal control system, which is the target application for this technology. Tests were performed on an Engineering Development Unit at NASA s Johnson Space Center to quantify and assess the performance of the SDC. Correlated thermal math models were developed to help explain the test data. The paper also outlines the preliminary results of an ISDC concept being developed.

  2. Techniques used for limiting degradation products of polymeric materials for use in the space environment

    NASA Technical Reports Server (NTRS)

    Vest, C. E.; Park, J. J.

    1978-01-01

    Techniques are discussed for limiting or controlling the degradation products (outgassing) of polymeric materials in the space environment. One technique, now ASTM E-595-77, is used to screen out those materials which lose greater than 1% Total Mass Loss when in vacuum for 24 hours at 125 C and which have more than 0.10% Collected Volatile Condensable Materials condensing on a collector surface at 25 C. Examples of silicone materials which are high and low in outgassing are given. The numerous mechanical motions in spacecraft experiments require liquid lubricants which also might degrade in space. Labyrinth seals and barrier films are utilized to limit the degradation of or from these lubricants. A recoverable in-flight experiment has been proposed for making definitive measurements of how effective these techniques are in limiting the amounts and escape paths of outgassed molecules.

  3. MOSAIC - A space-multiplexing technique for optical processing of large images

    NASA Technical Reports Server (NTRS)

    Athale, Ravindra A.; Astor, Michael E.; Yu, Jeffrey

    1993-01-01

    A technique for Fourier processing of images larger than the space-bandwidth products of conventional or smart spatial light modulators and two-dimensional detector arrays is described. The technique involves a spatial combination of subimages displayed on individual spatial light modulators to form a phase-coherent image, which is subsequently processed with Fourier optical techniques. Because of the technique's similarity with the mosaic technique used in art, the processor used is termed an optical MOSAIC processor. The phase accuracy requirements of this system were studied by computer simulation. It was found that phase errors of less than lambda/8 did not degrade the performance of the system and that the system was relatively insensitive to amplitude nonuniformities. Several schemes for implementing the subimage combination are described. Initial experimental results demonstrating the validity of the mosaic concept are also presented.

  4. Signal Detection Techniques for Diagnostic Monitoring of Space Shuttle Main Engine Turbomachinery

    NASA Technical Reports Server (NTRS)

    Coffin, Thomas; Jong, Jen-Yi

    1986-01-01

    An investigation to develop, implement, and evaluate signal analysis techniques for the detection and classification of incipient mechanical failures in turbomachinery is reviewed. A brief description of the Space Shuttle Main Engine (SSME) test/measurement program is presented. Signal analysis techniques available to describe dynamic measurement characteristics are reviewed. Time domain and spectral methods are described, and statistical classification in terms of moments is discussed. Several of these waveform analysis techniques have been implemented on a computer and applied to dynamc signals. A laboratory evaluation of the methods with respect to signal detection capability is described. A unique coherence function (the hyper-coherence) was developed through the course of this investigation, which appears promising as a diagnostic tool. This technique and several other non-linear methods of signal analysis are presented and illustrated by application. Software for application of these techniques has been installed on the signal processing system at the NASA/MSFC Systems Dynamics Laboratory.

  5. Measurement of vapor pressures and heats of sublimation of dicarboxylic acids using atmospheric solids analysis probe mass spectrometry.

    PubMed

    Bruns, Emily A; Greaves, John; Finlayson-Pitts, Barbara J

    2012-06-21

    Vapor pressures of low volatility compounds are important parameters in several atmospheric processes, including the formation of new particles and the partitioning of compounds between the gas phase and particles. Understanding these processes is critical for elucidating the impacts of aerosols on climate, visibility, and human health. Dicarboxylic acids are an important class of compounds in the atmosphere for which reported vapor pressures often vary by more than an order of magnitude. In this study, atmospheric solids analysis probe mass spectrometry (ASAP-MS), a relatively new atmospheric pressure ionization technique, is applied for the first time to the measurement of vapor pressures and heats of sublimation of a series of dicarboxylic acids. Pyrene was also studied because its vapor pressures and heat of sublimation are relatively well-known. The heats of sublimation measured using ASAP-MS were in good agreement with published values. The vapor pressures, assuming an evaporation coefficient of unity, were typically within a factor of ∼3 lower than published values made at similar temperatures for most of the acids. The underestimation may be due to diffusional constraints resulting from evaporation at atmospheric pressure. However, this study establishes that ASAP-MS is a promising new technique for such measurements. PMID:22432524

  6. A numerical technique for obaining the complete bifurcated equilibrium solution space for a Tokamak

    SciTech Connect

    Helton, F.J.; Greene, J.M.

    1992-01-01

    This paper describes a new numerical method for finding solutions to the ideal MHD equilibrium problem The space of solutions thus found can have more than one bifurcation branch, depending on the tokamak being modeled. We suggest that the solutions which are difficult to obtain without the use of this technique correspond to equilibria which are difficult to maintain in the tokamak being modeled. First, this paper investigates, for a tokamak design with large poloidal field-shaping coil (PFC) to plasma distance, the bifurcated numerical solution curve as a function of flux loop position and relates this curve to the practical existence of ideal magnetohydrodynamic equilibria and practical tokamak design. In previous papers, some of the problems which could arise for large PFC-plasma distance were discussed. Then, using a regularization technique, it was shown that, for large PFC-plasma distance, the flux loops should be close to the PFCs for stable control if the full information form the flux loops is used. Here it is shown that, for large PFC-plasma distance, the structure of the equilibrium solution space becomes increasingly complex and desirable solutions become more difficult to attain as the flux loops are moved farther from the plasma. In order to explore this solution space numerically, it is necessary to obtain solutions for which the usual Picard iteration method is unstable. Here an extension of this method is given. The solution space is enlarged by adding additional variable and constraints, so that the iteration to the desired solution is stable in the extended space. A modified version of this numerical technique has been used to obtain equilibrium fits to highly elongated DIII-D plasmas. The numerical equilibria are very difficult to obtain without the use of this technique and the plasmas are difficult to maintain in the tokamak. 10 refs., 6 figs., 2 tabs.

  7. Evaluating Local Primary Dendrite Arm Spacing Characterization Techniques Using Synthetic Directionally Solidified Dendritic Microstructures

    NASA Astrophysics Data System (ADS)

    Tschopp, Mark A.; Miller, Jonathan D.; Oppedal, Andrew L.; Solanki, Kiran N.

    2015-10-01

    Microstructure characterization continues to play an important bridge to understanding why particular processing routes or parameters affect the properties of materials. This statement certainly holds true in the case of directionally solidified dendritic microstructures, where characterizing the primary dendrite arm spacing is vital to developing the process-structure-property relationships that can lead to the design and optimization of processing routes for defined properties. In this work, four series of simulations were used to examine the capability of a few Voronoi-based techniques to capture local microstructure statistics (primary dendrite arm spacing and coordination number) in controlled (synthetically generated) microstructures. These simulations used both cubic and hexagonal microstructures with varying degrees of disorder (noise) to study the effects of length scale, base microstructure, microstructure variability, and technique parameters on the local PDAS distribution, local coordination number distribution, bulk PDAS, and bulk coordination number. The Voronoi tesselation technique with a polygon-side-length criterion correctly characterized the known synthetic microstructures. By systematically studying the different techniques for quantifying local primary dendrite arm spacings, we have evaluated their capability to capture this important microstructure feature in different dendritic microstructures, which can be an important step for experimentally correlating with both processing and properties in single crystal nickel-based superalloys.

  8. Vapor pressures and enthalpies of sublimation of D-glucose, D-xylose, cellobiose, and levoglucosan

    SciTech Connect

    Oja, V.; Suuberg, E.M.

    1999-01-01

    The vapor pressures of {alpha}-D-glucose (or dextrose), D-xylose, D-cellobiose (or 4-{beta}-D-glucopyranosyl-D-glucopyranose), and levoglucosan (or 1,6-anhydro-{beta}-D-glucopyranose) have been measured using the Knudsen effusion technique, in the range of temperatures from 344 to 488 K. The measurements were all made in the solid sublimation regime, and enthalpies of sublimation were calculated from the Clausius-Claperon equation. The vapor pressures may be correlated by ln(P/Pa) = A {minus} B/(T/K), where A = 53.16, B = 23.382 ({+-}600) for D-glucose (395--406 K), A = 46.29 and B = 19,006 ({+-} 375) for D-xylose (370--395 K), and A = 70.30 and B = 36,264 ({+-} 5,220) for cellobiose (474--488 K). Levoglucosan displayed a solid phase transition at approximately 386 K, and its vapor pressure was affected accordingly. For this material, A = 38.96 and B = 15,049 ({+-} 123) in the temperature range 344--386 K and A = 31.19 and B = 12,066 ({+-} 709) in the temperature range 386--405 K.

  9. GaAs surface cleaning by thermal oxidation and sublimation in molecular-beam epitaxy

    NASA Astrophysics Data System (ADS)

    Saito, Junji; Nanbu, Kazuo; Ishikawa, Tomonori; Kondo, Kazuo

    1988-01-01

    GaAs surface cleaning by thermal oxidation and sublimation prior to molecular-beam-epitaxial growth has been investigated as a means of reducing the carrier depletion at the substrate and epitaxial layer interface. The carrier depletion between the substrate and epitaxial films, measured by a C-V carrier profiling technique, was shown to decrease significantly with an increase in the thickness of the thermal oxidation. The concentration of carbon contamination near the substrate-epitaxial interface was measured using secondary ion mass spectroscopy. The carbon concentration correlated very well with the carrier depletion. Therefore, the main origin of the carrier depletion is believed to be the carbon concentration of the initial growth surface. Based on these results, the thermal oxidation and sublimation of a semi-insulating GaAs substrate was successfully applied to improve the mobility and sheet concentration of the two-dimensional electron gas in selectively doped GaAs/N-Al0.3Ga0.7As heterostructures with very thin GaAs buffer layers.

  10. Use of reduced basis technique in the inverse dynamics of large space cranes

    NASA Technical Reports Server (NTRS)

    Das, S. K.; Utku, S.; Wada, B. K.

    1990-01-01

    The inverse dynamics of adaptive structures used as space cranes can prove computationally expensive in the case of large structures, due to the large number of degrees of freedom involved. Consequently, reduced basis techniques (reduction techniques) are frequently used to reduce the problem size to a time manageable level (for possible use in real time control). A reduced basis technique is proposed which is different from, but related to, the path-derivatives reduction technique. A linearly independent set of deflection n-tuples is used, chosen at the beginning of the time range in which it is wished to reduce the equations, in whose subspace it is assumed that the deflection vectors of the unreduced problem will lie (approximately).

  11. Evaluation of nondestructive testing techniques for the space shuttle nonmetallic thermal protection system

    NASA Technical Reports Server (NTRS)

    Tiede, D. A.

    1972-01-01

    A program was conducted to evaluate nondestructive analysis techniques for the detection of defects in rigidized surface insulation (a candidate material for the Space Shuttle thermal protection system). Uncoated, coated, and coated and bonded samples with internal defects (voids, cracks, delaminations, density variations, and moisture content), coating defects (holes, cracks, thickness variations, and loss of adhesion), and bondline defects (voids and unbonds) were inspected by X-ray radiography, acoustic, microwave, high-frequency ultrasonic, beta backscatter, thermal, holographic, and visual techniques. The detectability of each type of defect was determined for each technique (when applicable). A possible relationship between microwave reflection measurements (or X-ray-radiography density measurements) and the tensile strength was established. A possible approach for in-process inspection using a combination of X-ray radiography, acoustic, microwave, and holographic techniques was recommended.

  12. Coupled fluid-thermal analysis of low-pressure sublimation and condensation with application to freeze-drying

    NASA Astrophysics Data System (ADS)

    Ganguly, Arnab

    Freeze-drying is a low-pressure, low-temperature condensation pumping process widely used in the manufacture of bio-pharmaceuticals for removal of solvents by sublimation. The goal of the process is to provide a stable dosage form by removing the solvent in such a way that the sensitive molecular structure of the active substance is least disturbed. The vacuum environment presents unique challenges for understanding and controlling heat and mass transfer in the process. As a result, the design of equipment and associated processes has been largely empirical, slow and inefficient. A comprehensive simulation framework to predict both, process and equipment performance is critical to improve current practice. A part of the dissertation is aimed at performing coupled fluid-thermal analysis of low-pressure sublimation-condensation processes typical of freeze-drying technologies. Both, experimental and computational models are used to first understand the key heat transfer modes during the process. A modeling and computational framework, validated with experiments for analysis of sublimation, water-vapor flow and condensation in application to pharmaceutical freeze-drying is developed. Augmented with computational fluid dynamics modeling, the simulation framework presented here allows to predict for the first time, dynamic product/process conditions taking into consideration specifics of equipment design. Moreover, by applying the modeling framework to process design based on a design-space approach, it has demonstrated that there is a viable alternative to empiricism.

  13. Properties of filamentary sublimation residues from dispersions of clay in ice. [on Martian poles, comet nuclei, and icy satellites

    NASA Technical Reports Server (NTRS)

    Saunders, R. S.; Parker, T. J.; Stephens, J. B.; Fanale, F. P.; Sutton, S.

    1986-01-01

    Results are reported from experimental studies of the formation of ice mixed with mineral particles in an effort to simulate similar processes on natural surfaces such as at the Martian poles, on comet nuclei and on icy satellites. The study consisted of low-pressure, low-temperature sublimations of water ice from dilutions of water-clay (montmorillonite and Cabosil) dispersions of various component ratios. Liquid dispersions were sprayed into liquid nitrogen to form droplets at about -50 C. Both clay-water dispersions left a filamentary residue on the bottom of the Dewar after the water ice had sublimated off. The residue was studied with optical and SEM microscopy, the latter method revealing a high electrical conductivity in the residue. The results suggest that the sublimation of the water ice can leave a surface crust, which may be analogous to processes at the Martian poles and on comet nuclei. The process could proceed by the attachment of water molecules to salt crystals during the hottest part of the Martian year. The residue remaining was found to remain stable up to 370 C, be porous, and remain resilient, which could allow it to insulate ice bodies such as comets in space.

  14. A Real-Time High Performance Data Compression Technique For Space Applications

    NASA Technical Reports Server (NTRS)

    Yeh, Pen-Shu; Venbrux, Jack; Bhatia, Prakash; Miller, Warner H.

    2000-01-01

    A high performance lossy data compression technique is currently being developed for space science applications under the requirement of high-speed push-broom scanning. The technique is also error-resilient in that error propagation is contained within a few scan lines. The algorithm is based on block-transform combined with bit-plane encoding; this combination results in an embedded bit string with exactly the desirable compression rate. The lossy coder is described. The compression scheme performs well on a suite of test images typical of images from spacecraft instruments. Hardware implementations are in development; a functional chip set is expected by the end of 2001.

  15. MetricMap: an embedding technique for processing distance-based queries in metric spaces.

    PubMed

    Wang, Jason T L; Wang, Xiong; Shasha, Dennis; Zhang, Kaizhong

    2005-10-01

    In this paper, we present an embedding technique, called MetricMap, which is capable of estimating distances in a pseudometric space. Given a database of objects and a distance function for the objects, which is a pseudometric, we map the objects to vectors in a pseudo-Euclidean space with a reasonably low dimension while preserving the distance between two objects approximately. Such an embedding technique can be used as an approximate oracle to process a broad class of distance-based queries. It is also adaptable to data mining applications such as data clustering and classification. We present the theory underlying MetricMap and conduct experiments to compare MetricMap with other methods including MVP-tree and M-tree in processing the distance-based queries. Experimental results on both protein and RNA data show the good performance and the superiority of MetricMap over the other methods. PMID:16240772

  16. General-Purpose Stereo Imaging Velocimetry Technique Developed for Space and Industrial Applications

    NASA Technical Reports Server (NTRS)

    McDowell, Mark

    2004-01-01

    A new three-dimensional, full-field analysis technique has been developed for industrial and space applications. Stereo Imaging Velocimetry (SIV) will provide full-field analysis for three-dimensional flow data from any optically transparent fluid that can be seeded with tracer particles. The goal of SIV is to provide a means to measure three-dimensional fluid velocities quantitatively and qualitatively at many points. SIV is applicable to any optically transparent fluid experiment. Except for the tracer particles, this measurement technique is nonintrusive. Velocity accuracies are on the order of 95 to 99 percent of fullfield. The system components of SIV include camera calibration, centroid determination, overlap decomposition, particle tracking, stereo matching, and three-dimensional velocity analysis. SIV has been used successfully for space shuttle experiments as well as for fluid flow applications for business and industry.

  17. Utilization of artificial intelligence techniques for the Space Station power system

    NASA Technical Reports Server (NTRS)

    Evatt, Thomas C.; Gholdston, Edward W.

    1988-01-01

    Due to the complexity of the Space Station Electrical Power System (EPS) as currently envisioned, artificial intelligence/expert system techniques are being investigated to automate operations, maintenance, and diagnostic functions. A study was conducted to investigate this technology as it applies to failure detection, isolation, and reconfiguration (FDIR) and health monitoring of power system components and of the total system. Control system utilization of expert systems for load scheduling and shedding operations was also researched. A discussion of the utilization of artificial intelligence/expert systems for Initial Operating Capability (IOC) for the Space Station effort is presented along with future plans at Rocketdyne for the utilization of this technology for enhanced Space Station power capability.

  18. Acoustic levitation technique for containerless processing at high temperatures in space

    NASA Technical Reports Server (NTRS)

    Rey, Charles A.; Merkley, Dennis R.; Hammarlund, Gregory R.; Danley, Thomas J.

    1988-01-01

    High temperature processing of a small specimen without a container has been demonstrated in a set of experiments using an acoustic levitation furnace in the microgravity of space. This processing technique includes the positioning, heating, melting, cooling, and solidification of a material supported without physical contact with container or other surface. The specimen is supported in a potential energy well, created by an acoustic field, which is sufficiently strong to position the specimen in the microgravity environment of space. This containerless processing apparatus has been successfully tested on the Space Shuttle during the STS-61A mission. In that experiment, three samples wer successfully levitated and processed at temperatures from 600 to 1500 C. Experiment data and results are presented.

  19. Measurements of strain at plate boundaries using space based geodetic techniques

    NASA Technical Reports Server (NTRS)

    Robaudo, Stefano; Harrison, Christopher G. A.

    1993-01-01

    We have used the space based geodetic techniques of Satellite Laser Ranging (SLR) and VLBI to study strain along subduction and transform plate boundaries and have interpreted the results using a simple elastic dislocation model. Six stations located behind island arcs were analyzed as representative of subduction zones while 13 sites located on either side of the San Andreas fault were used for the transcurrent zones. The length deformation scale was then calculated for both tectonic margins by fitting the relative strain to an exponentially decreasing function of distance from the plate boundary. Results show that space-based data for the transcurrent boundary along the San Andreas fault help to define better the deformation length scale in the area while fitting nicely the elastic half-space earth model. For subduction type bonndaries the analysis indicates that there is no single scale length which uniquely describes the deformation. This is mainly due to the difference in subduction characteristics for the different areas.

  20. Advanced techniques for free-space optical quantum cryptography over water

    NASA Astrophysics Data System (ADS)

    Hill, Alexander D.; Christensen, Bradley; Kwiat, Paul G.

    2016-03-01

    Free-space quantum key distribution (QKD) over water (e.g., ship to ship) may be limited by ship motion and atmospheric effects, such as mode distortion and beam wander due to turbulence. We report on a technique which reduces noise by excluding spatial modes which are less likely to contain QKD signal photons and experimentally demonstrate an improvement in QKD key generation rates in various noise and turbulence regimes.

  1. Coarse-Grain Bandwidth Estimation Techniques for Large-Scale Space Network

    NASA Technical Reports Server (NTRS)

    Cheung, Kar-Ming; Jennings, Esther

    2013-01-01

    In this paper, we describe a top-down analysis and simulation approach to size the bandwidths of a store-andforward network for a given network topology, a mission traffic scenario, and a set of data types with different latency requirements. We use these techniques to estimate the wide area network (WAN) bandwidths of the ground links for different architecture options of the proposed Integrated Space Communication and Navigation (SCaN) Network.

  2. Computer Vision Techniques Applied to Space Object Detect, Track, ID, Characterize

    NASA Astrophysics Data System (ADS)

    Flewelling, B.

    2014-09-01

    Space-based object detection and tracking represents a fundamental step necessary for detailed analysis of space objects. Initial observations of a resident space object (RSO) may result from careful sensor tasking to observe an object with well understood dynamics, or measurements-of-opportunity on an object with poorly understood dynamics. Dim and eccentric objects present a particular challenge which requires more dynamic use of imaging systems. As a result of more stressing data acquisition strategies, advanced techniques for the accurate processing of both point and streaking sources are needed. This paper will focus on two key methods in computer vision used to determine interest points within imagery. The Harris Corner method and the method of Phase Congruency can be used to effectively extract static and streaking point sources and to indicate when apparent motion is present within an observation. The geometric inferences which can be made from the resulting detections will be discussed, including a method to evaluate the localization uncertainty of the extracted detections which is based on the computation of the Hessian of the detector response. Finally a technique which exploits the additional information found in detected streak endpoints to provide a better centroid in the presence of curved streaks is explained and additional applications for the presented techniques are discussed.

  3. Acoustic puncture assist device versus loss of resistance technique for epidural space identification

    PubMed Central

    Mittal, Amit Kumar; Goel, Nitesh; Chowdhury, Itee; Shah, Shagun Bhatia; Singh, Brijesh Pratap; Jakhar, Pradeep

    2016-01-01

    Background and Aims: The conventional techniques of epidural space (EDS) identification based on loss of resistance (LOR) have a higher chance of complications, patchy analgesia and epidural failure, which can be minimised by objective confirmation of space before catheter placement. Acoustic puncture assist device (APAD) technique objectively confirms EDS, thus enhancing success, with lesser complications. This study was planned with the objective to evaluate the APAD technique and compare it to LOR technique for EDS identification and its correlation with ultrasound guided EDS depth. Methods: In this prospective study, the lumbar vertebral spaces were scanned by the ultrasound for measuring depth of the EDS and later correlated with procedural depth measured by either of the technique (APAD or LOR). The data were subjected to descriptive statistics; the concordance correlation coefficient and Bland-Altman analysis with 95% confidence limits. Results: Acoustic dip in pitch and descent in pressure tracing on EDS localisation was observed among the patients of APAD group. Analysis of concordance correlation between the ultrasonography (USG) depth and APAD or LOR depth was significant (r ≥ 0.97 in both groups). Bland-Altman analysis revealed a mean difference of 0.171cm in group APAD and 0.154 cm in group LOR. The 95% limits of agreement for the difference between the two measurements were − 0.569 and 0.226 cm in APAD and − 0.530 to 0.222 cm in LOR group. Conclusion: We found APAD to be a precise tool for objective localisation of the EDS, co-relating well with the pre-procedural USG depth of EDS. PMID:27212720

  4. Characterization of Carbon Dioxide Washout Measurement Techniques in the Mark-III Space Suit

    NASA Technical Reports Server (NTRS)

    Meginnis, I; Norcross, J.; Bekdash, O.

    2016-01-01

    techniques for future CO2 washout limits in space suits

  5. Surveying co-located space geodesy techniques for ITRF computation: statistical aspects

    NASA Astrophysics Data System (ADS)

    Sillard, P.; Sarti, P.; Vittuari, L.

    2003-04-01

    For two years, CNR (ITALY) has been involved in a complete renovation of the way Space Geodesy coloocated instruments are surveyed. Local ties are one of the most problematic part of International Terrestrial Reference Frame (ITRF) computation since the accuracy of Space Geodesy techniques has decreased to a few millimeters level. Therefore everybody now agrees on the fact that local ties are one of the most problematic aspects of the ITRF computation. The CNR has then decided to start a comprehensive reflection on the way local ties should be surveyed between Space Geodesy instruments. This reflection concerns the practical ground operations, the physical definition of a Space Geodesy instrument reference point (especially for VLBI), and the consequent adjustment of the results, as well as their publication. The two first aspects will be presented in an other presentation as the present one will focus on the two last points (statistics and publication). As Space Geodesy has now reached the mm level, local ties must be used in ITRF computation with a full variance covariance matrix available for one site. The talk will present the way this variance can be derived, even when the reference point is implicitly defined, like for VLBI. Some numerical examples will be given of the quality which can be reached through a rigorous statistical treatment of the new approach developed by CNR. The evidence of the significant improvement that can be seen of the ITRF-type computation will also be given.

  6. Application of separable parameter space techniques to multi-tracer PET compartment modeling

    NASA Astrophysics Data System (ADS)

    Zhang, Jeff L.; Morey, A. Michael; Kadrmas, Dan J.

    2016-02-01

    Multi-tracer positron emission tomography (PET) can image two or more tracers in a single scan, characterizing multiple aspects of biological functions to provide new insights into many diseases. The technique uses dynamic imaging, resulting in time-activity curves that contain contributions from each tracer present. The process of separating and recovering separate images and/or imaging measures for each tracer requires the application of kinetic constraints, which are most commonly applied by fitting parallel compartment models for all tracers. Such multi-tracer compartment modeling presents challenging nonlinear fits in multiple dimensions. This work extends separable parameter space kinetic modeling techniques, previously developed for fitting single-tracer compartment models, to fitting multi-tracer compartment models. The multi-tracer compartment model solution equations were reformulated to maximally separate the linear and nonlinear aspects of the fitting problem, and separable least-squares techniques were applied to effectively reduce the dimensionality of the nonlinear fit. The benefits of the approach are then explored through a number of illustrative examples, including characterization of separable parameter space multi-tracer objective functions and demonstration of exhaustive search fits which guarantee the true global minimum to within arbitrary search precision. Iterative gradient-descent algorithms using Levenberg-Marquardt were also tested, demonstrating improved fitting speed and robustness as compared to corresponding fits using conventional model formulations. The proposed technique overcomes many of the challenges in fitting simultaneous multi-tracer PET compartment models.

  7. Application of separable parameter space techniques to multi-tracer PET compartment modeling

    PubMed Central

    Zhang, Jeff L; Morey, A Michael; Kadrmas, Dan J

    2016-01-01

    Multi-tracer positron emission tomography (PET) can image two or more tracers in a single scan, characterizing multiple aspects of biological functions to provide new insights into many diseases. The technique uses dynamic imaging, resulting in time-activity curves that contain contributions from each tracer present. The process of separating and recovering separate images and/or imaging measures for each tracer requires the application of kinetic constraints, which are most commonly applied by fitting parallel compartment models for all tracers. Such multi-tracer compartment modeling presents challenging nonlinear fits in multiple dimensions. This work extends separable parameter space kinetic modeling techniques, previously developed for fitting single-tracer compartment models, to fitting multi-tracer compartment models. The multi-tracer compartment model solution equations were reformulated to maximally separate the linear and nonlinear aspects of the fitting problem, and separable least-squares techniques were applied to effectively reduce the dimensionality of the nonlinear fit. The benefits of the approach are then explored through a number of illustrative examples, including characterization of separable parameter space multi-tracer objective functions and demonstration of exhaustive search fits which guarantee the true global minimum to within arbitrary search precision. Iterative gradient-descent algorithms using Levenberg–Marquardt were also tested, demonstrating improved fitting speed and robustness as compared to corresponding fits using conventional model formulations. The proposed technique overcomes many of the challenges in fitting simultaneous multi-tracer PET compartment models. PMID:26788888

  8. Demonstration of a High-Fidelity Predictive/Preview Display Technique for Telerobotic Servicing in Space

    NASA Technical Reports Server (NTRS)

    Kim, Won S.; Bejczy, Antal K.

    1993-01-01

    A highly effective predictive/preview display technique for telerobotic servicing in space under several seconds communication time delay has been demonstrated on a large laboratory scale in May 1993, involving the Jet Propulsion Laboratory as the simulated ground control station and, 2500 miles away, the Goddard Space Flight Center as the simulated satellite servicing set-up. The technique is based on a high-fidelity calibration procedure that enables a high-fidelity overlay of 3-D graphics robot arm and object models over given 2-D TV camera images of robot arm and objects. To generate robot arm motions, the operator can confidently interact in real time with the graphics models of the robot arm and objects overlaid on an actual camera view of the remote work site. The technique also enables the operator to generate high-fidelity synthetic TV camera views showing motion events that are hidden in a given TV camera view or for which no TV camera views are available. The positioning accuracy achieved by this technique for a zoomed-in camera setting was about +/-5 mm, well within the allowable +/-12 mm error margin at the insertion of a 45 cm long tool in the servicing task.

  9. Formulation and verification of frequency response system identification techniques for large space structures

    NASA Technical Reports Server (NTRS)

    Mitchell, Jerrel R.; Jones, Victoria L.; Plant, Charles

    1988-01-01

    For the past several years much effort has been given to the development of techniques for designing control systems for large space structures (LSS's). The main objective of these efforts has been to develop a LSS control methodology that produces designs that meet strenuous performance requirements and are robust to model inaccuracies. Unfortunately, performance and robustness are conflicting requirements. Because LSS's can not be fully tested on ground, it has become an accepted fact that the design of LSS control systems to meet performance requirements can not be completed until the LSS is placed on-orbit and tested and an accurate model is extracted from on-orbit test results. Modern MIMO sampled-data frequency response design techniques are viable candidates for designing LSS control systems. First, this paper presents techniques for performing MIMO system identification (ID) from test data. Then, techniques for improving the performance of the system ID process in the presence of noise are presented. Finally, practical utility of the system ID approaches are validated by the presentation of results obtained from application on the LSS Ground Test Facility at Marshall Space Flight Center.

  10. Modelling of the sublimation of icy grains in the coma of comet 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Gicquel, A.; Vincent, J.-B.; Shi, X.; Sierks, H.; Rose, M.; Güttler, C.; Tubiana, C.

    2015-10-01

    The ESA (European Space Agency) Rosetta spacecraft was launched on 2 March 2004, to reach comet 67P/Churyumov-Gerasimenko in August 2014. Since March 2014, images of the nucleus and the coma (gas and dust) of the comet have been acquired by the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) camera system [1] using both, the wide angle camera (WAC) and the narrow angle camera (NAC). The orbiter will be maintained in the vicinity of the comet until perihelion (Rh=1.3 AU) or even until Rh=1.8 AU post-perihelion (December 2015). Nineteen months of uninterrupted, close-up observations of the gas and dust coma will be obtained and will help to characterize the evolution of comet gas and dust activity during its approach to the Sun. Indeed, for the first time, we will follow the development of a comet's coma from a close distance. Also the study of the dust-gas interaction in the coma will highlight the sublimation of icy grains. Even if the sublimation of icy grains is known, it is not yet integrated in a complete dust-gas model. We are using the Direct Simulation Monte Carlo (DSMC) method to study the gas flow close to the nucleus. The code called PI-DSMC (www.pidsmc. com) can simulate millions of molecules for multiple species.When the gas flow is simulated, we inject the dust particle with a zero velocity and we take into account the 3 forces acting on the grains in a cometary environment (drag force, gravity and radiative pressure). We used the DLL (Dynamic Link Library) model to integrate the sublimation of icy grains in the gas flowand allow studying the effect of the additional gas on the dust particle trajectories. For a quantitative analysis of the sublimation of icy, outflowing grains we will consider an ensemble of grains of various radii with different compositions [2] The evolution of the grains, once they are ejected into the coma, depends on their initial size, their composition and the heliocentric distance (because the temperature of