Science.gov

Sample records for medium temperature application

  1. Metal glass vacuum tube solar collectors are approaching lower-medium temperature heat application.

    PubMed

    Jiang, Xinian

    2010-04-26

    Solar thermal collectors are widely used worldwide mainly for hot water preparation at a low temperature (less than 80 degrees C). Applications including many industrial processes and central air conditioning with absorption chillers, instead require lower-medium temperature heat (between 90 degrees C and 150 degrees C) to be driven when using solar thermal energy. The metal absorber glass vacuum tube collectors (MGVT) are developed for this type of applications. Current state-of-art and possible future technology development of MGVT are presented. PMID:20607893

  2. Metal glass vacuum tube solar collectors are approaching lower-medium temperature heat application.

    PubMed

    Jiang, Xinian

    2010-04-26

    Solar thermal collectors are widely used worldwide mainly for hot water preparation at a low temperature (less than 80?C). Applications including many industrial processes and central air conditioning with absorption chillers, instead require lower-medium temperature heat (between 90 degrees C and 150 degrees C) to be driven when using solar thermal energy. The metal absorber glass vacuum tube collectors (MGVT) are developed for this type of applications. Current state-of-art and possible future technology development of MGVT are presented. PMID:20588568

  3. Theoretical analysis of screened heat pipes for medium and high temperature solar applications

    NASA Astrophysics Data System (ADS)

    Di Marco, P.; Filippeschi, S.; Franco, A.; Jafari, D.

    2014-11-01

    A mathematical model is applied to study the cylindrical heat pipes (HPs) behaviour when it is exposed to higher heat input at the evaporator for solar collector applications. The steady state analytical model includes two-dimensional heat conduction in the wall, the liquid flow in the wick and vapour hydrodynamics, and can be used to evaluate the working limits and to optimize the HP. The results of the analytical model are compared with numerical and experimental results available in literature, with good agreement. The effects of heat transfer coefficient, power input, evaporator length, pipe diameter, wick thickness and effective pore radius on the vapour temperature, maximum pressure drop and maximum heat transfer capability (HTC) of the HP are studied. The analysis shows that wick thickness plays an important role in the enhancement of HTC. Results show that it is possible to improve HTC of a HP by selecting the appropriate wick thickness, effective pore radius, and evaporator length. The parametric investigations are aimed to determine working limits and thermal performance of HP for medium temperature solar collector application.

  4. Kinetic studies of dry sorent for medium temperature applications. Final report

    SciTech Connect

    Keener, T.C.; Wang, Z.

    1996-07-12

    The purpose of this project is to investigate the fundamental nature of sorbent reactivity and reaction kinetics in the medium temperature range from 600{degrees}F (316{degrees}C) to 1200{degrees}F (649{degrees}C) available in the convective pass of a boiler upstream of the economizer, where dry sorbents are injected to remove SO{sub 2} from the flue gas. Research focuses on the mechanisms of sorbent- flue gas interaction under economizer and hot baghouse conditions utilizing the experimental setup and the results of the first four years of research.

  5. Medium-scale surface temperature mission: MUST

    NASA Astrophysics Data System (ADS)

    Duthil, Philippe; Vidal, Alain; Dubet, Dominique

    1997-12-01

    The medium scale surface temperature (MUST) mission, studied in the frame of a European Commission (DG XII) contract, is a large swath (1200 Km), medium resolution (250 m) thermal infra-red imager mission devoted to retrieve the land surface temperature in order to serve various applications. These applications are firstly those concerned with the soil and vegetation water status (agriculture, irrigation and water resources management) as evapotranspiration and soil moisture can be inferred from surface temperature through relevant models. The other applications are either directly using the surface temperature (some frosts conditions assessment) or the air temperature that is itself derived from surface temperature extrapolation (urban heat island, some air frosts conditions). The project basically aimed to demonstrate the relevance and efficiency of the MUST mission products in the relevant application fields and to assess the economical benefits of the mission. Also in the course of the study the design of a medium resolution, large swath thermal imager, providing the appropriate performance required by the users while compact and affordable, was produced. Finally the operational implementation of the system and especially the ground segment was considered.

  6. Comprehensive Compressor Calorimeter Testing of Lower-GWP Alternative Refrigerants for Heat Pump and Medium Temperature Refrigeration Applications

    SciTech Connect

    Shrestha, Som S; Sharma, Vishaldeep; Abdelaziz, Omar

    2014-01-01

    In response to environmental concerns raised by the use of refrigerants with high Global Warming Potential (GWP), the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) has launched an industry-wide cooperative research program, referred to as the Low-GWP Alternative Refrigerants Evaluation Program (AREP), to identify and evaluate promising alternative refrigerants for major product categories. This paper reports one of the Oak Ridge National Laboratory (ORNL) contributions to AREP. It compares performance of alternative refrigerants to that of R-410A and R-404A for heat pump and medium temperature applications, respectively. The alternatives reported in this paper are: R-32, DR-5, and L-41a for R-410A and ARM-31a, D2Y-65, L-40, and a mixture of R-32 and R-134a for R-404A. All performance comparison tests were conducted using scroll compressors of ~1.85 tons (6.5 kW) cooling capacity. Tests were conducted over a range of combinations of saturation suction and saturation discharge temperatures for both compressors. The tests showed that, in general, energy efficiency ratio (EER) and cooling capacity of R-410A alternative refrigerants were slightly lower than that of the baseline refrigerant with a moderate increases in discharge temperature. On the other hand, R-404A alternative refrigerants showed relative performance dependence on saturation suction and saturation discharge temperatures and larger increases in discharge temperature than for the R-410A alternatives. This paper summarizes the relative performance of all alternative refrigerants compared to their respective baseline.

  7. Temperature Distribution in a Uniformly Moving Medium

    ERIC Educational Resources Information Center

    Mitchell, Joseph D.; Petrov, Nikola P.

    2009-01-01

    We apply several physical ideas to determine the steady temperature distribution in a medium moving with uniform velocity between two infinite parallel plates. We compute it in the coordinate frame moving with the medium by integration over the "past" to account for the influence of an infinite set of instantaneous point sources of heat in past…

  8. Simplified modeling of liquid sodium medium with temperature and velocity gradient using real thermal-hydraulic data. Application to ultrasonic thermometry in sodium fast reactor

    NASA Astrophysics Data System (ADS)

    Massacret, N.; Moysan, J.; Ploix, M. A.; Jeannot, J. P.; Corneloup, G.

    2013-01-01

    In the framework of the French R&D program for the Generation IV reactors and specifically for the sodium cooled fast reactors (SFR), studies are carried out on innovative instrumentation methods in order to improve safety and to simplify the monitoring of fundamental physical parameters during reactor operation. The aim of the present work is to develop an acoustic thermometry method to follow up the sodium temperature at the outlet of subassemblies. The medium is a turbulent flow of liquid sodium at 550 °C with temperature inhomogeneities. To understand the effect of disturbance created by this medium, numerical simulations are proposed. A ray tracing code has been developed with Matlabin order to predict acoustic paths in this medium. This complex medium is accurately described by thermal-hydraulic data which are issued from a simulation of a real experiment in Japan. The analysis of these results allows understanding the effects of medium inhomogeneities on the further thermometric acoustic measurement.

  9. Infrared spectroscopic and conductivity studies of ureasil-based proton conducting membranes for medium temperature fuel cell applications.

    PubMed

    Vince, Jelica; Vuk, Angela Šurca; Stangar, Urška Lavrenčič; Perše, Lidija Slemenik; Orel, Boris; Hočevar, Stanko

    2010-12-01

    Proton conducting membranes for fuel cells were prepared by the sol-gel process from two different ureasil organic-inorganic hybrid precursors: bis[(N-(3-triethoxysilylpropyl)ureido]-terminated poly(propylene glycol) 4000 (PPGU) and bis[3-(N-(3-triethoxysilylpropyl)ureido)propyl]-terminated poly(dimethylsiloxane) 1000 (PDMSU). Heteropoly silicotungstic acid was added to actuate the reactions of hydrolysis and condensation and to introduce proton conductivity. XRD measurements of membranes revealed the presence of a diffraction peak at 6.3°, which could be ascribed to gradual formation of R-(SiO3/2) silsesquioxane clusters, i.e. arrangement of the Si-O-Si skeleton on the nano-scale. TG and DSC measurements showed thermal stability of the membranes above 120 °C. Proton conductivities at room temperature were of the order of 10-4 to 10-3 S/cm, classifying the membranes in the group of super ionic conductors. At elevated temperatures up to 160 °C and at conditions of autogenous pressure, conductivities increased up to values acceptable for fuel cells of 10-1 S/cm, which could be the result of the presence of H3O+ ions. The protonation of the urea groups and the formation of amidonium ions [C(OH)=NH+] were followed using IR ATR spectroscopy. PMID:24061888

  10. Medium Deep High Temperature Heat Storage

    NASA Astrophysics Data System (ADS)

    Bär, Kristian; Rühaak, Wolfram; Schulte, Daniel; Welsch, Bastian; Chauhan, Swarup; Homuth, Sebastian; Sass, Ingo

    2015-04-01

    Heating of buildings requires more than 25 % of the total end energy consumption in Germany. Shallow geothermal systems for indirect use as well as shallow geothermal heat storage systems like aquifer thermal energy storage (ATES) or borehole thermal energy storage (BTES) typically provide low exergy heat. The temperature levels and ranges typically require a coupling with heat pumps. By storing hot water from solar panels or thermal power stations with temperatures of up to 110 °C a medium deep high temperature heat storage (MDHTS) can be operated on relatively high temperature levels of more than 45 °C. Storage depths of 500 m to 1,500 m below surface avoid conflicts with groundwater use for drinking water or other purposes. Permeability is typically also decreasing with greater depth; especially in the crystalline basement therefore conduction becomes the dominant heat transport process. Solar-thermal charging of a MDHTS is a very beneficial option for supplying heat in urban and rural systems. Feasibility and design criteria of different system configurations (depth, distance and number of BHE) are discussed. One system is designed to store and supply heat (300 kW) for an office building. The required boreholes are located in granodioritic bedrock. Resulting from this setup several challenges have to be addressed. The drilling and completion has to be planned carefully under consideration of the geological and tectonical situation at the specific site.

  11. Simplified modeling of liquid sodium medium with temperature and velocity gradient using real thermal-hydraulic data. Application to ultrasonic thermometry in sodium fast reactor

    SciTech Connect

    Massacret, N.; Jeannot, J. P.

    2013-01-25

    In the framework of the French R and D program for the Generation IV reactors and specifically for the sodium cooled fast reactors (SFR), studies are carried out on innovative instrumentation methods in order to improve safety and to simplify the monitoring of fundamental physical parameters during reactor operation. The aim of the present work is to develop an acoustic thermometry method to follow up the sodium temperature at the outlet of subassemblies. The medium is a turbulent flow of liquid sodium at 550 Degree-Sign C with temperature inhomogeneities. To understand the effect of disturbance created by this medium, numerical simulations are proposed. A ray tracing code has been developed with Matlab Copyright-Sign in order to predict acoustic paths in this medium. This complex medium is accurately described by thermal-hydraulic data which are issued from a simulation of a real experiment in Japan. The analysis of these results allows understanding the effects of medium inhomogeneities on the further thermometric acoustic measurement.

  12. Application of Quenching and Partitioning Processing to Medium Mn Steel

    NASA Astrophysics Data System (ADS)

    Seo, Eun Jung; Cho, Lawrence; De Cooman, Bruno C.

    2015-01-01

    The present work analyzes the application of quenching and partitioning processing to medium Mn steel to obtain a new type of ultra-high-strength multiphase medium Mn steel. The selection of the quench temperature makes it possible to vary the ultimate tensile strength within a range of 500 MPa. The processing leads to low-carbon lath martensite matrix with a controlled volume fraction of retained austenite.

  13. Longitudinal temperature distribution in an end-pumped solid-state amplifier medium: application to a high average power diode pumped Yb:YAG thin disk amplifier.

    PubMed

    Bourdet, Gilbert L; Yu, Haiwu

    2007-08-10

    We propose a simple analytical derivation making it possible to compute a one-dimensional temperature variation in an end-pumped solid-state laser. This derivation takes into account the pump intensity variation along the crystal, the doping concentration, and temperature dependence of the thermal conductivity. We then compare this simulation with the one usually used, which does not take into account any of these dependences. The results show that, at room temperature, the two methods are in good agreement, but at a cryogenic temperature where the thermal conductivity varies fast with temperature, a large discrepancy is found, and the conventional computations underestimate both the average temperature and the longitudinal gradient. PMID:17694159

  14. 27 CFR 19.675 - Medium plant permit applications.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Medium plant permit... Obtaining A Permit § 19.675 Medium plant permit applications. (a) General. Any person wishing to establish a medium plant must file form TTB F 5110.74, Application and Permit for an Alcohol Fuel Producer Under 26...

  15. 27 CFR 19.675 - Medium plant permit applications.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Medium plant permit... Obtaining A Permit § 19.675 Medium plant permit applications. (a) General. Any person wishing to establish a medium plant must file form TTB F 5110.74, Application and Permit for an Alcohol Fuel Producer Under 26...

  16. 27 CFR 19.675 - Medium plant permit applications.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Medium plant permit... Obtaining A Permit § 19.675 Medium plant permit applications. (a) General. Any person wishing to establish a medium plant must file form TTB F 5110.74, Application and Permit for an Alcohol Fuel Producer Under 26...

  17. 27 CFR 19.675 - Medium plant permit applications.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Medium plant permit... Obtaining A Permit § 19.675 Medium plant permit applications. (a) General. Any person wishing to establish a medium plant must file form TTB F 5110.74, Application and Permit for an Alcohol Fuel Producer Under 26...

  18. Corrosion Resistant Coatings for High Temperature Applications

    SciTech Connect

    Besman, T.M.; Cooley, K.M.; Haynes, J.A.; Lee, W.Y.; Vaubert, V.M.

    1998-12-01

    Efforts to increase efficiency of energy conversion devices have required their operation at ever higher temperatures. This will force the substitution of higher-temperature structural ceramics for lower temperature materials, largely metals. Yet, many of these ceramics will require protection from high temperature corrosion caused by combustion gases, atmospheric contaminants, or the operating medium. This paper discusses examples of the initial development of such coatings and materials for potential application in combustion, aluminum smelting, and other harsh environments.

  19. Cyanides/isocyanides abundances in the interstellar medium - IV. Temperature dependence of SiCN/SiNC rate coefficients and astrophysical applications

    NASA Astrophysics Data System (ADS)

    Hernández Vera, M.; Lique, F.; Kłos, J.; Dumouchel, F.; Rubayo Soneira, J.

    2015-08-01

    Accurate determination of collisional rate coefficients is an essential step in the estimation of the SiCN and SiNC abundances in the interstellar and circumstellar media. In this paper, we carry out calculations of rate coefficients for the rotational (de-)excitation of SiCN and SiNC molecules in collision with He. The calculations are based on new two-dimensional potential energy surfaces obtained from highly correlated ab initio calculations. Coupled-States quantum approximation was used in the scattering calculations to obtain collisional (de-)excitation cross-sections of SiCN and SiNC by He. The spin-orbit coupling and Λ-doublet splitting of SiCN and SiNC levels were taken into account explicitly. Rate coefficients for transitions among the first 92 rotational levels of SiCN and SiNC were calculated for temperatures ranging from 5 to 100 K. Moderate differences exist between the rate coefficients of both isomers. Subsequently, the new collisional data are used to simulate the excitation of SiCN and SiNC in the circumstellar gas. We obtain the brightness and excitation temperatures of selected lines frequently observed towards the circumstellar envelopes and we find that local thermodynamic equilibrium conditions are not fulfilled for these species. Radiative transfer calculations are then needed in order to accurately determine their abundances. Our results also show that previous estimations of the cyanides/isocyanides abundance ratios were incorrect and the present calculations show that SiCN, the most stable isomer, is more abundant than SiNC. This shows again the evidence of selective cyanide chemistry.

  20. Oil displacement through a porous medium with a temperature gradient

    NASA Astrophysics Data System (ADS)

    Oliveira, Cláudio L. N.; Andrade, José S., Jr.; Herrmann, Hans J.

    2011-06-01

    We investigate the effect of a temperature gradient on oil recovery in a two-dimensional pore-network model. The oil viscosity depends on temperature as μo∝eB/T, where B is a physicochemical parameter, depending on the type of oil, and T is the temperature. A temperature gradient is applied across the medium in the flow direction. Initially, the porous medium is saturated with oil, and then another fluid is injected. We have considered two cases representing different injection strategies. In the first case, the invading fluid viscosity is constant (finite viscosity ratio), while in the second one, the invading fluid is inviscid (infinite viscosity ratio). Our results show that for the case of finite viscosity ratio, recovery increases with ΔT independent of strength or sign of the gradient. For an infinite viscosity ratio, a positive temperature gradient is necessary to enhance recovery. Moreover, we show that for ΔT>0, the percentage of oil recovery generally decreases (increases) with B for a finite (infinite) viscosity ratio. Finally, we also extend our results for infinite viscosity ratio to a three-dimensional porous media geometry.

  1. Conversion of medium and low temperature heat to power

    NASA Astrophysics Data System (ADS)

    Fischer, Johann; Wendland, Martin; Lai, Ngoc Anh

    2013-04-01

    Presently most electricity is produced in power plants which use high temperature heat supplied by coal, oil, gas or nuclear fission and Clausius-Rankine cycles (CRC) with water as working fluid (WF). On the other hand, geo-, solar-, ocean-, and biogenic-heat have medium and low temperatures. At these temperatures, however, the use of other WF and/or other cycles can yield higher efficiencies than those of the water-CRC. For an assessment of the efficiency we model systems which include the heat transfer to and from the WF and the cycle. Optimization criterion is the exergy efficiency defined as the ratio of the net power output to the incoming exergy flow of the heat carrier. First, for a better understanding we discuss some thermodynamic properties of the WFs: 1) the critical point parameters, 2) the shape of the vapour- liquid coexistence curve in the temperature vs entropy (T,s)-diagram which may be either bell-shaped or overhanging [1,2], and 3) the shape of sub- and supercritical isobars for pure fluids and fluid mixtures. Second, we show that the problems of a CRC with water at lower temperatures are 1) the shape of the T,s-diagram and 2) the exergy loss during heat transfer to the WF. The first problem can be overcome by using an organic working fluid in the CRC which then is called organic Rankine cycle (ORC). The second problem is reduced by supercritical organic Rankine cycles (sORC) [1,2], trilateral cycles (TLC) and the more general power-flash cycles (PFC) [2], and organic flash cycles (OFC) [3]. Next, selected results for systems with the above mentioned cycles will be presented. The heat carrier inlet temperatures THC range from 120°C to 350°C.The pure working fluids are water, refrigerants, alkanes, aromates and siloxanes and have to be selected to match with THC. It is found that TLC with water have the highest efficiencies but show very large volume flows at lower temperatures. Moreover, expansion machines for TLC and PFC are still under

  2. Effect of Coupling Medium Temperature on Rate of Intramuscular Temperature Rise Using Continuous Ultrasound

    PubMed Central

    Oshikoya, Corey A.; Shultz, Sandra J.; Mistry, Danny; Perrin, David H.; Arnold, Brent L.; Gansneder, Bruce M.

    2000-01-01

    Objective: We determined the effects of coupling medium temperature on the rate of intramuscular temperature rise (RTR) during continuous ultrasound. Design and Setting: Ultrasound was applied in a continuous mode at a frequency of 1 MHz and intensity of 1.5 W/cm². Each subject received 3 treatments, using water-based coupling gel at temperatures of 18°C, 25°C, and 39°C. All treatments were performed in an athletic training room under controlled environmental conditions. Subjects: Eighteen healthy male subjects (mean age = 23.6 ± 3.5 years; height = 177.8 ± 6.9 cm; weight = 76.6 ± 8.2 kg; calf size = 37.6 ± 2.4 cm) participated in this study. Measurements: A thermistor was inserted into the left medial triceps surae at a depth of 5 cm, and baseline tissue temperatures were recorded before treatment. Intramuscular temperature was recorded every 30 seconds until the temperature rose 4°C above baseline or until discomfort was felt. RTR was calculated by dividing the absolute temperature change by treatment time. Results: A 1-way, repeated-measures analysis of variance revealed a significant difference in RTR among gel temperatures, RTR was significantly faster using the 25°C gel compared with the 18°C and 39°C gels. There was no difference between the 18°C and 39°C gel treatments. Conclusions: These results suggest that the use of a cooled or heated gel may be counterproductive when maximal thermal effects are desired within a given time frame. PMID:16558655

  3. Measurements of the gain medium temperature in an operating Cs DPAL.

    PubMed

    Zhdanov, B V; Rotondaro, M D; Shaffer, M K; Knize, R J

    2016-08-22

    A Mach-Zehnder interferometer was used for contactless measurement of the temperature of the gain medium within a static cell of Cs DPAL. The maximum temperature recorded approached 700° C leading to a significant degradation of laser performance. This work also examined lasing and non-lasing heat deposition and has shown that as much as 85% of the heating in a DPAL gain medium can be attributed to quenching. PMID:27557208

  4. Investigation of medium and high temperature phase change materials

    NASA Technical Reports Server (NTRS)

    Heine, D.; Kraehling, H.

    1979-01-01

    A detailed description of the programs for acquisition and analysis of the test results is given. Basically it concerns three programs. The TEST program controls the recording of the test data. With the THELLI program it is possible to follow the temperature curve recorded for each individual thermoelement during the test. With the AUSW program the test data can be analyzed, to determine, for example, the melting point and the start of melting. The first results of the service life tests are discussed. From these it is attempted to draw inferences for the subsequent tests. An attempt is made to focus on the determination of the area-related mass loss, the reduction in thickness and the corrosion rate as well as optical and scanning electron microscope evaluation.

  5. Near and medium infrared optical fiber lasers and emerging applications

    NASA Astrophysics Data System (ADS)

    Prudenzano, F.; Mescia, L.; Allegretti, L.; De Sario, M.; D'Orazio, A.; Di Tommaso, A.; Palmisano, T.; Petruzzelli, V.

    2010-02-01

    Laser cavities emitting in the near and medium infrared wavelength range, made of rare earth doped optical fibers and suitable pairs of integrated mirrors, are used in a large number of applications. Nowadays, the efficient employment of near and medium infrared laser beams is largely widespread in the field of m*aterial processing, surgery, directed energy, remote sensing, spectroscopy, imaging, and so on. In a lot of cases, the high conversion efficiency, the excellent beam quality, the compactness and, the good heat dissipation capability make fiber lasers competitive and attractive with respect to other light sources, such as ion-doped crystal and bulk glass lasers, optical parametric oscillators, semiconductor and gas lasers. The paper aims to recall and/or briefly illustrate a few among the numerous strategies recently followed by research laboratories and industries to obtain laser sources based on rare earth doped optical fibres. A recall on the host materials and the dopants employed for their construction, and the corresponding applications is given, too. Moreover, an example of near infrared (NIR) fiber optic laser development, by employing available on market components is illustrated by underlining the possibility to easily obtain high beam quality.

  6. Energy cost based design optimization method for medium temperature CPC collectors

    NASA Astrophysics Data System (ADS)

    Horta, Pedro; Osório, Tiago; Collares-Pereira, Manuel

    2016-05-01

    CPC collectors, approaching the ideal concentration limits established by non-imaging optics, can be designed to have such acceptance angles enabling fully stationary designs, useful for applications in the low temperature range (T < 100°C). Their use in the medium temperature range (100°C < T < 250°C) typically requires higher concentration factors in turn requiring seasonal tracking strategies. Considering the CPC design options in terms of effective concentration factor, truncation, concentrator height, mirror perimeter, seasonal tracking, trough spacing, etc., an energy cost function based design optimization method is presented in this article. Accounting for the impact of the design on its optical (optical efficiency, Incidence Angle Modifier, diffuse acceptance) and thermal performances (dependent on the concentration factor), the optimization function integrates design (e.g. mirror area, frame length, trough spacing/shading), concept (e.g. rotating/stationary components, materials) and operation (e.g. O&M, tilt shifts and tracking strategy) costs into a collector specific energy cost function, in €/(kWh.m2). The use of such function stands for a location and operating temperature dependent design optimization procedure, aiming at the lowest solar energy cost. Illustrating this approach, optimization results will be presented for a (tubular) evacuated absorber CPC design operating in Morocco.

  7. Biophotonic applications of eigenchannels in a scattering medium (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kim, Moonseok; Choi, Wonjun; Choi, Youngwoon; Yoon, Changhyeong; Choi, Wonshik

    2016-03-01

    When waves travel through disordered media such as ground glass and skin tissues, they are scattered multiple times. Most of the incoming energy bounces back at the superficial layers and only a small fraction can penetrate deep inside. This has been a limiting factor for the working depth of various optical techniques. We present a systematic method to enhance wave penetration to the scattering media. Specifically, we measured the reflection matrix of a disordered medium with wide angular coverage for each orthogonal polarization states. From the reflection matrix, we identified reflection eigenchannels of the medium, and shaped the incident wave into the reflection eigenchannel with smallest eigenvalue, which we call anti-reflection mode. This makes reflectance reduced and wave penetration increased as a result of the energy conservation. We demonstrated transmission enhancement by more than a factor of 3 by the coupling of the incident waves to the anti-reflection modes. Based on the uneven distribution of eigenvalues of reflection eigenchannels, we further developed an iterative feedback control method for finding and coupling light to anti-reflection modes. Since this adaptive control method can keep up with sample perturbation, it promotes the applicability of exploiting reflection eigenchannels. Our approach of delivering light deep into the scattering media will contribute to enhancing the sensitivity of detecting objects hidden under scattering layers, which is universal problem ranging from geology to life science.

  8. Medium Range Ensembles Flood Forecasts for Community Level Applications

    NASA Astrophysics Data System (ADS)

    Fakhruddin, S.; Kawasaki, A.; Babel, M. S.; AIT

    2013-05-01

    Early warning is a key element for disaster risk reduction. In recent decades, there has been a major advancement in medium range and seasonal forecasting. These could provide a great opportunity to improve early warning systems and advisories for early action for strategic and long term planning. This could result in increasing emphasis on proactive rather than reactive management of adverse consequences of flood events. This can be also very helpful for the agricultural sector by providing a diversity of options to farmers (e.g. changing cropping pattern, planting timing, etc.). An experimental medium range (1-10 days) flood forecasting model has been developed for Bangladesh which provides 51 set of discharge ensembles forecasts of one to ten days with significant persistence and high certainty. This could help communities (i.e. farmer) for gain/lost estimation as well as crop savings. This paper describe the application of ensembles probabilistic flood forecast at the community level for differential decision making focused on agriculture. The framework allows users to interactively specify the objectives and criteria that are germane to a particular situation, and obtain the management options that are possible, and the exogenous influences that should be taken into account before planning and decision making. risk and vulnerability assessment was conducted through community consultation. The forecast lead time requirement, users' needs, impact and management options for crops, livestock and fisheries sectors were identified through focus group discussions, informal interviews and questionnaire survey.

  9. Temperature sensors for OTEC applications

    NASA Astrophysics Data System (ADS)

    Seren, L.; Panchal, C. B.; Rote, D. M.

    1984-05-01

    Ocean thermal energy conversion (OTEC) applications require accurate measurement of temperatures in the 0 to 30 C range. Commercially available quartz-crystal thermometers and thermistors were examined. Three fixed-point baths were used for temperature measurements: the distilled-water/distilled-ice-water slurry, the triple-point-of-water cell, and the gallium melting-point cell. The temperature of carefully prepared ice-water slurries was verified routinely as 0.001 + or - 0.003 C. Quartz-crystal probes proved accurate to about 1 to 2 mK, with drift errors of the same order over a few days. Bead and disk-type thermistor probes were found to be about equally stable with time in the 0 to 30 C range. The overall probable error of using thermistors was found to be + or -4 mK. A solid-block temperature bath suitable for on-site calibrations in OTEC work was used in the temperature-sweeping mode. Various polynomial fits were examined for thermistor calibration; fits of order two and higher yielded about equally accurate calculated temperatures.

  10. Formation of bubbly horizon in liquid-saturated porous medium by surface temperature oscillation.

    PubMed

    Goldobin, Denis S; Krauzin, Pavel V

    2015-12-01

    We study nonisothermal diffusion transport of a weakly soluble substance in a liquid-saturated porous medium in contact with a reservoir of this substance. The surface temperature of the porous medium half-space oscillates in time, which results in a decaying solubility wave propagating deep into the porous medium. In this system, zones of saturated solution and nondissolved phase coexist with ones of undersaturated solution. The effect is first considered for the case of annual oscillation of the surface temperature of water-saturated ground in contact with the atmosphere. We reveal the phenomenon of formation of a near-surface bubbly horizon due to temperature oscillation. An analytical theory of the phenomenon is developed. Further, the treatment is extended to the case of higher frequency oscillations and the case of weakly soluble solids and liquids. PMID:26764828

  11. Formation of bubbly horizon in liquid-saturated porous medium by surface temperature oscillation

    NASA Astrophysics Data System (ADS)

    Goldobin, Denis S.; Krauzin, Pavel V.

    2015-12-01

    We study nonisothermal diffusion transport of a weakly soluble substance in a liquid-saturated porous medium in contact with a reservoir of this substance. The surface temperature of the porous medium half-space oscillates in time, which results in a decaying solubility wave propagating deep into the porous medium. In this system, zones of saturated solution and nondissolved phase coexist with ones of undersaturated solution. The effect is first considered for the case of annual oscillation of the surface temperature of water-saturated ground in contact with the atmosphere. We reveal the phenomenon of formation of a near-surface bubbly horizon due to temperature oscillation. An analytical theory of the phenomenon is developed. Further, the treatment is extended to the case of higher frequency oscillations and the case of weakly soluble solids and liquids.

  12. Thermal stresses in the wall of pipes caused by periodic change of temperature of medium fluid

    NASA Astrophysics Data System (ADS)

    Atefi, Gholamali; Mahmoudi, Hamid

    2012-06-01

    The problem of thermal stresses induced in pipes due to periodic change of medium fluid temperature has never been considered completely. In this paper an analytical solution for obtaining thermal stresses in a pipe caused by periodic time varying of temperature of medium fluid is offered. Transient heat conduction equation in cylindrical coordinates for a long hollow cylinder under periodic change of ambient temperature condition is solved analytically using Fourier series and Temperature distribution in the wall of pipe as a function of time and radial direction is specified. Then resulting thermal stresses are obtained using thermoelasticity relations. Because of the use of Fourier series expansion in obtaining the transient temperature field the proposed method is very comprehensive and covers many theoretical and practical problems. The results for thermal stresses have been compared with former works and show excellent agreement for the same conditions.

  13. Effect of Intercritical Annealing Temperature on Phase Transformations in Medium Carbon Dual Phase Steels

    NASA Astrophysics Data System (ADS)

    Erişir, Ersoy; Bilir, Oğuz Gürkan

    2014-03-01

    This paper presents a study concerning phase transformations during quenching of a medium carbon dual phase steel using thermodynamic equilibrium calculations and dilatometry. Medium carbon steel was subjected to the intermediate quenching to produce a fine grained ferrite/martensite dual phase steel. 4 samples quenched after intercritical annealing at 725, 730, 740, and 750 °C. Martensite-start and bainite-start temperatures were calculated from dilatometric curves using plastodilotemeter. Experimental findings are supported by calculated phase diagrams and equilibrium phase compositions using ThermoCalc® and calculations from different empirical formulas. It is concluded that martensite-start temperature depend on chemical composition and grain size of austenite.

  14. Increased medium-range order in amorphous silicon with increased substrate temperature

    SciTech Connect

    Voyles, P. M.; Gerbi, J. E.; Treacy, M. M. J.; Gibson, J. M.; Aberlson, J. R.

    2000-08-15

    Using fluctuation electron microscopy, the authors have measured the medium-range order of magnetron sputtered silicon thin films as a function of substrate temperature from the amorphous to polycrystalline regimes. They find a smooth increase in the medium-range order of the samples, which they interpret in the context of the paracrystalline structural model as an increase in the size of and/or volume fraction occupied by the paracrystalline grains. These data are counter to the long-standing belief that there is a sharp transition between amorphous and polycrystalline structures as a function of substrate temperature.

  15. Heavy quark scattering and quenching in a QCD medium at finite temperature and chemical potential

    NASA Astrophysics Data System (ADS)

    Berrehrah, H.; Bratkovskaya, E.; Cassing, W.; Gossiaux, P. B.; Aichelin, J.

    2015-05-01

    The heavy quark collisional scattering on partons of the quark gluon plasma (QGP) is studied in a quantum chromodynamics medium at finite temperature and chemical potential. We evaluate the effects of finite parton masses and widths, finite temperature T , and quark chemical potential μq on the different elastic cross sections for dynamical quasiparticles (on- and off-shell particles in the QGP medium as described by the dynamical quasiparticle model "DQPM") using the leading order Born diagrams. Our results show clearly the decrease of the q Q and g Q total elastic cross sections when the temperature and the quark chemical potential increase. These effects are amplified for finite μq at temperatures lower than the corresponding critical temperature Tc(μq) . Using these cross sections we, furthermore, estimate the energy loss and longitudinal and transverse momentum transfers of a heavy quark propagating in a finite temperature and chemical potential medium. Accordingly, we have shown that the transport properties of heavy quarks are sensitive to the temperature and chemical potential variations. Our results provide some basic ingredients for the study of charm physics in heavy-ion collisions at Beam Energy Scan at RHIC and CBM experiment at FAIR.

  16. Proton conducting, composite sulfonated polymer membrane for medium temperature and low relative humidity fuel cells

    NASA Astrophysics Data System (ADS)

    Shin, Dong Won; Kang, Na Rae; Lee, Kang Hyuck; Cho, Doo Hee; Kim, Ji Hoon; Lee, Won Hyo; Lee, Young Moo

    2014-09-01

    Inorganic-organic composite membranes are fabricated using zirconium acetylacetonate nanoparticles and biphenol-based sulfonated poly(arylene ether sulfone) as an inorganic, proton conducting nanomaterial and a polymer matrix, respectively. An amphiphilic surfactant (Pluronic®) induces distribution of the inorganic nanoparticles over the entire polymer membrane. The composite membranes are thermally stable up to 200 °C. Zirconium acetylacetonate improves inter-chain interactions and the robustness of polymer membranes resulting in excellent membrane mechanical properties. In addition, composite membranes show outstanding proton conductivity compared to that of the pristine membrane at medium temperatures (80-120 °C) and low relative humidity (<50%) conditions. This improvement is due to the presence of acetylacetonate anions, which bind water molecules and act as an additional proton conducting site and/or medium. Therefore, the composite membranes significantly outperform the pristine membrane in fuel cell performance tests at medium temperatures and low relative humidity.

  17. D* and B* mesons in strange hadronic medium at finite temperature

    NASA Astrophysics Data System (ADS)

    Chhabra, Rahul; Kumar, Arvind

    2016-03-01

    We calculate the effect of density and temperature of isospin symmetric strange medium on the shift in masses and decay constants of vector D and B mesons using chiral SU(3) model and QCD sum rule approach. In the present investigation the values of quark and gluon condensates are calculated from the chiral SU(3) model and these condensatesare further used as input in the QCD Sum rule framework to calculate the in-medium masses and decay constants of vector D and B mesons. These in medium properties of vector D and B mesons may be helpful to understand the experimental observables of the experiments like CBM and PANDA under FAIR project at GSI, Germany. The results which are observed in present work are also compared with the previous predictions.

  18. Inverse coefficient problems for one-dimensional heat transfer with a preservation of medium temperature condition

    NASA Astrophysics Data System (ADS)

    Oralsyn, Gulaym

    2016-08-01

    We study an inverse coefficient problem for a model equation for one-dimensional heat transfer with a preservation of medium temperature. It is needed (together with finding its solution) to find time dependent unknown coefficient of the equation. So, for this inverse problem, existence of an unique generalized solution is proved. The main difficulty of the considered problems is that the eigenfunction system of the corresponding boundary value problems does not have the basis property.

  19. Low Temperature Detectors: Principles and Applications

    SciTech Connect

    Hilton, G. C.

    2009-12-16

    Despite the added cost and complexity of operating at sub-Kelvin temperatures, there are many measurement applications where the sensitivity and precision provided by low temperature detectors greatly outweigh any disadvantages. As a result, low temperature detectors are now finding wide application for measurements ranging from cosmology to homeland defense. In this tutorial I will introduce the basic operating principles and fundamental performance limits of several types of low temperature detectors.

  20. CHARACTERIZATION OF INTRACLUSTER MEDIUM TEMPERATURE DISTRIBUTIONS OF 62 GALAXY CLUSTERS WITH XMM-NEWTON

    SciTech Connect

    Frank, K. A.; Peterson, J. R.; Andersson, K.; Fabian, A. C.; Sanders, J. S.

    2013-02-10

    We measure the intracluster medium (ICM) temperature distributions for 62 galaxy clusters in the HIFLUGCS, an X-ray flux-limited sample, with available X-ray data from XMM-Newton. We search for correlations between the width of the temperature distributions and other cluster properties, including median cluster temperature, luminosity, size, presence of a cool core, active galactic nucleus (AGN) activity, and dynamical state. We use a Markov Chain Monte Carlo analysis, which models the ICM as a collection of X-ray emitting smoothed particles of plasma. Each smoothed particle is given its own set of parameters, including temperature, spatial position, redshift, size, and emission measure. This allows us to measure the width of the temperature distribution, median temperature, and total emission measure of each cluster. We find that none of the clusters have a temperature width consistent with isothermality. Counterintuitively, we also find that the temperature distribution widths of disturbed, non-cool-core, and AGN-free clusters tend to be wider than in other clusters. A linear fit to {sigma} {sub kT}-kT {sub med} finds {sigma} {sub kT} {approx} 0.20kT {sub med} + 1.08, with an estimated intrinsic scatter of {approx}0.55 keV, demonstrating a large range in ICM thermal histories.

  1. Sensors for low temperature application

    DOEpatents

    Henderson, Timothy M.; Wuttke, Gilbert H.

    1977-01-01

    A method and apparatus for low temperature sensing which uses gas filled micro-size hollow glass spheres that are exposed in a confined observation area to a low temperature range (Kelvin) and observed microscopically to determine change of state, i.e., change from gaseous state of the contained gas to condensed state. By suitable indicia and classification of the spheres in the observation area, the temperature can be determined very accurately.

  2. Temperature- and medium-dependent secretion of proteins by Shiga toxin-producing Escherichia coli.

    PubMed Central

    Ebel, F; Deibel, C; Kresse, A U; Guzmán, C A; Chakraborty, T

    1996-01-01

    Infections due to Shiga toxin-producing Escherichia coli (STEC) are responsible for severe diarrheal disease in humans and livestock, and these bacteria have recently emerged as a leading cause of renal failure in children. In this study, we have examined medium- and temperature-dependent production of secreted proteins from a STEC O26 serotype strain. Growth of bacteria in Luria broth led to the detection of secreted polypeptides of 104, 55, 54, and 37 kDa (p104, p55, p54, and p37, respectively). When grown in serum-free tissue culture medium, only p104, p37 and two additional polypeptides of 25 and 22 kDa (p25 and p22) were present in supernatant fluids. Production of these polypeptides was growth temperature dependent and induced in cultures grown at 37 degrees C. N-terminal amino acid sequencing revealed that p104 was homologous to the secreted p110 of enteropathogenic Escherichia coli (EPEC), and both proteins belong to a family of secreted proteins in pathogenic bacteria of which the immunoglobulin A protease of Neisseria gonorrhoeae is the prototype. The N-terminal amino acid sequences of p55 and p54 were unique to the STEC strain, while p37 and p25 were found to be highly homologous to the similarly sized EspA and EspB proteins, previously detected in culture supernatants of EPEC. Molecular cloning and sequencing of STEC espB alleles from two different serotypes showed that the encoded polypeptides were about 80% homologous. A monoclonal antibody raised against STEC EspB also cross-reacted with its EPEC analog and allowed us to demonstrate medium- and temperature-dependent production of this important virulence factor in STEC and EPEC strains of differing serotypes. PMID:8890194

  3. Unsteady magnetohydrodynamic free convection flow of a second grade fluid in a porous medium with ramped wall temperature.

    PubMed

    Samiulhaq; Ahmad, Sohail; Vieru, Dumitru; Khan, Ilyas; Shafie, Sharidan

    2014-01-01

    Magnetic field influence on unsteady free convection flow of a second grade fluid near an infinite vertical flat plate with ramped wall temperature embedded in a porous medium is studied. It has been observed that magnitude of velocity as well as skin friction in case of ramped temperature is quite less than the isothermal temperature. Some special cases namely: (i) second grade fluid in the absence of magnetic field and porous medium and (ii) Newtonian fluid in the presence of magnetic field and porous medium, performing the same motion are obtained. Finally, the influence of various parameters is graphically shown. PMID:24785147

  4. Unsteady Magnetohydrodynamic Free Convection Flow of a Second Grade Fluid in a Porous Medium with Ramped Wall Temperature

    PubMed Central

    Samiulhaq; Ahmad, Sohail; Vieru, Dumitru; Khan, Ilyas; Shafie, Sharidan

    2014-01-01

    Magnetic field influence on unsteady free convection flow of a second grade fluid near an infinite vertical flat plate with ramped wall temperature embedded in a porous medium is studied. It has been observed that magnitude of velocity as well as skin friction in case of ramped temperature is quite less than the isothermal temperature. Some special cases namely: (i) second grade fluid in the absence of magnetic field and porous medium and (ii) Newtonian fluid in the presence of magnetic field and porous medium, performing the same motion are obtained. Finally, the influence of various parameters is graphically shown. PMID:24785147

  5. Effects of temperature and medium composition on inhibitory activities of gossypol-related compounds against aflatoxigenic fungi

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of temperature and medium composition on growth/aflatoxin inhibitory activities of gossypol, gossypolone and apogossypolone against Aspergillus flavus and A. parasiticus were investigated. The compounds were tested in a Czapek agar medium at 25 C, 31 C and 37 C at a concentration of 100 µg ...

  6. Temperature and relative humidity distributions in a medium-size administrative town in southwest Nigeria.

    PubMed

    Akinbode, O M; Eludoyin, A O; Fashae, O A

    2008-04-01

    This study was carried out in one of the medium-sized public administrative towns in the southwestern part of Nigeria. Its aim is to highlight the effect of spatial distribution of settlements, population, and socio-economic activities on urban air temperature and humidity in the town. Temperature and relative humidity data from 1992 to 2001 were obtained from three meteorological stations in Akure, the Administrative Capital of Ondo State, Nigeria. The stations are located within the Federal Ministry of Aviation, Akure Airport (FMA), Federal University of Technology, Akure (FUTA) and Federal School of Agriculture (SOA). Air temperature and relative humidity measurements were also obtained from 27 points, which were cited to include road junctions, markets, built up areas, etc., using sling psychrometer. The data were subsequently analysed for spatial and temporal variations using statistical packages (SPSS and Microsoft Excel) and isolines. Actual vapour pressure and dew point temperature were computed using Magnus conversion formulae. The results obtained showed that spatial variation was insignificant, in terms of the temperature and humidity variables. The annual mean temperature (Tmean) ranged between 21.9 and 30.4 degrees C while minimum (Tmin) and maximum (Tmax) temperatures varied from 13 to 26 and 21.5-39.6 degrees C, respectively. Relative humidity (RH), actual vapour pressure (Es) and dew point temperature (Td) values also varied from 39.1% to 98.2%, 19.7-20.8 gm(-3), and 17.3-17.8 degrees C, respectively. A significant relationship (p>0.6; r<0.05) between Tmin, Es and Td was observed while the daytime 'urban heat island' intensity (UHI) ranged between 0.5 and 2.5 degrees C within the study period. The study concluded that there is influence of urban canopy on the microclimate of Akure, and hypothesizes that the urban dwellers may be subjected to some levels of weather related physiological disorderliness. PMID:17482750

  7. The Temperature-Density Relation of the Intergalactic Medium after Hydrogen Reionization

    NASA Astrophysics Data System (ADS)

    Furlanetto, Steven R.; Oh, S. Peng

    2009-08-01

    We use an analytic model to study how inhomogeneous hydrogen reionization affects the temperature distribution of the intergalactic medium (IGM). During this process, the residual energy of each ionizing photon is deposited in the IGM as heat, increasing its temperature to 20,000-30,000 K; subsequent expansion of the universe then cools the gas. Because reionization most likely proceeds from high to low densities, underdense voids are ionized last, have less time to cool, and are (on average) warmer than mean-density gas immediately after reionization is complete (an "inverted" temperature-density relation). From this initial configuration, the low-density gas cools quickly and eventually returns to a more normal temperature-density relation. The rapidly evolving temperature introduces systematic uncertainties in measurements of the ionizing background at z ~ 6. For example, late reionization implies rapid cooling, so that the ionizing background would have to evolve even more rapidly at z ~ 5-6 than typically claimed. This degeneracy is difficult to disentangle, because the Lyα forest probes only a narrow range in densities (over which the gas is nearly isothermal). However, higher Lyman-series transitions probe wider density ranges, sampling different effective temperatures, and offer a new way to measure the IGM temperature-density relation that should work even where nearly saturated absorption precludes other methods. This will help to separate evolution in temperature from that in the ionizing background. While more detailed study with hydrodynamic simulations is needed, we show that such measurements could potentially distinguish early and late reionization using only a handful of lines of sight.

  8. Evaporation of Water Droplets in a High-Temperature Gaseous Medium

    NASA Astrophysics Data System (ADS)

    Vysokomornaya, O. V.; Kuznetsov, G. V.; Strizhak, P. A.

    2016-01-01

    A numerical solution of the problem of heat and mass transfer in evaporation of a droplet of water moving in a stream of high-temperature (up to 1200 K) gases is done on the basis of a system of nonlinear nonstationary partial differential equations describing conductive and radiative heat transfer in the droplet, as well as composite heat transfer at the ″liquid-gas″ interface. The values of the water evaporation rate have been determined. It is shown that the dependence of the evaporation rate on the droplet surface temperature has a nonlinear character. Characteristic relationships between the convective and radiative heat fluxes on the droplet surface (the radiative flux substantially exceeds the convective one; on decrease in the difference between the gas and droplet surface temperatures the difference between the radiative and convective heat fluxes decreases), the lifetimes (total evaporation) of droplets, as well as of the temperature and concentration of steam and gases in the vicinity of droplets have been determined. The calculated characteristics of the water droplet evaporation under conditions of high temperatures of the gas medium differ considerably from those obtained within the framework of the "diffusional" model of evaporation. A comparison of the results of numerical simulation with the experimental data obtained with the use of high-velocity panoramic optical methods of visualization by ″tracing particles″ is carried out.

  9. A rift-related origin for regional medium-pressure, high-temperature metamorphism

    NASA Astrophysics Data System (ADS)

    Tucker, Naomi M.; Hand, Martin; Payne, Justin L.

    2015-07-01

    Crustal-scale exhumation during the Alice Springs Orogeny (c. 450-320 Ma) in central Australia has exposed a region of medium-pressure, high-temperature metasedimentary and metabasic rocks that comprise the Harts Range Group (HRG). Similarities in the detrital zircon age spectra between the HRG and surrounding unmetamorphosed, intraplate late Neoproterozoic-Cambrian basin sequences suggest that the HRG is a highly metamorphosed equivalent of these successions. Calculated phase equilibria modelling and thermobarometry constrain peak metamorphic conditions to ˜ 880 °C and 10.5 kbar, and ˜ 680 °C and 5.5-8.0 kbar, in the structurally lowest and highest parts of the HRG, respectively. Metamorphic conditions also indicate that burial occurred along a near-linear moderately-high apparent thermal gradient, recorded by the prograde development of andalusite-bearing mineral assemblages at shallower structural levels. Prograde and peak metamorphism was associated with voluminous intrusive and extrusive mafic magmatism, the development of a coarse layer-parallel fabric and north-directed normal shear-sense kinematics. Collectively, these point to an extensional regime. Furthermore, burial and metamorphism at c. 480-460 Ma was concurrent with a shallow epicontinental marine environment and ongoing sedimentation in central Australia. Accordingly, the deep burial, metamorphism and deformation of the HRG to mid-lower crustal depths (˜ 20- 35 km) must be justified in the context of the broader intraplate basin evolution at this time. It is difficult to reconcile medium-pressure, high-temperature metamorphism of the HRG with deep burial by tectonic overthickening which is commonly assumed to be the case. In contrast, metamorphism of the HRG seems more compatible with burial within a deep rift-style basin driven by high heat flow and mafic magmatism, suggesting that regional medium-pressure metamorphic terranes are not necessarily reflective of compressional thickening of the

  10. Low-Temperature Blackbodies for IR Calibrations in a Medium-Background Environment

    NASA Astrophysics Data System (ADS)

    Ogarev, S. A.; Samoylov, M. L.; Parfentyev, N. A.; Sapritsky, V. I.

    2009-02-01

    Utilization of Earth remote-sensing data to solve scientific and engineering problems within such fields as meteorology and climatology requires precise radiometric calibration of space-borne instruments. High-accuracy calibration equipment in the thermal-IR wavelength range ought to be combined during calibration procedures with the simulation of environmental conditions for space orbit (high vacuum, medium background). For more than 35 years, VNIIOFI has developed and manufactured standard radiation sources in the form of precision blackbodies (BB) functioning within wide ranges of wavelengths and working temperatures. These BBs are the spectral radiance and irradiance calibration devices in the world’s leading space research institutions, such as SDL (USA), DLR (Germany), Keldysh Space Center (Russia), RNIIKP/RISDE (Russia), NEC Toshiba Space Systems (Japan), etc. The paper contains a detailed description of low-temperature precision BBs developed at VNIIOFI. The characteristics of variable-temperature (100 K to 400 K) research-grade extended-area (up to 350 mm) BB models BB100-V1 and BB-80/350 are described (they are intended for radiometric calibrations by comparison with a primary standard source), as well as those that can be used as sources for high-accuracy IR calibration of space-borne and other systems not requiring a vacuum environment. The temperature nonuniformity and stability of these BBs are (0.05 to 0.1) K (cavity-type BB100-V1), and 0.1 % for the (1.5 to 15) μm wavelength region under cryo-vacuum conditions of a medium-background environment.

  11. Influence of medium and temperature on the hydrolysis kinetics of propacetamol hydrochloride: determination using derivative spectrophotometry.

    PubMed

    Barcia, Emilia; Martin, Alicia; Azuara, Ma Luz; Negro, Sofia

    2005-03-01

    Propacetamol hydrochloride (PRO) is a water-soluble prodrug of paracetamol (PA) which can be parenterally administered as analgesic for the treatment of postoperative pain, acute trauma, and gastric and/or intestinal disorders where oral administration is not possible. In these circumstances, PRO can be administered in physiologic or glucose solutions since it is rapidly and quantitatively hydrolyzed into PA by plasma estearases. We have studied the degradation kinetics of PRO in 5% glucose and 0.9% saline solutions at 4 degrees C and 25 degrees C (storage and room temperatures, respectively). The analytic technique used to determine PRO and PA quantitatively was first-derivative spectrophotometry. The degradation process of PRO can be best fitted to a second-order kinetics with independence of the medium used (saline or glucose solution). The hydrolysis kinetics of PRO conversion into PA depends on the temperature but not on the assay medium (saline or glucose solution). The degradation rate constants obtained for PRO were approximately 4.5 times higher at 25 degrees C than at 4 degrees C. The values of t(90%) for PRO were 3.17 h and 3.61 h at 25 degrees C, and 13.42 h and 12.36 h at 4 degrees C when the tests were performed in 5% glucose and 0.9% saline solutions, respectively. PMID:15744097

  12. Motor for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Roopnarine (Inventor)

    2013-01-01

    A high temperature motor has a stator with poles formed by wire windings, and a rotor with magnetic poles on a rotor shaft positioned coaxially within the stator. The stator and rotor are built up from stacks of magnetic-alloy laminations. The stator windings are made of high temperature magnet wire insulated with a vitreous enamel film, and the wire windings are bonded together with ceramic binder. A thin-walled cylinder is positioned coaxially between the rotor and the stator to prevent debris from the stator windings from reaching the rotor. The stator windings are wound on wire spools made of ceramic, thereby avoiding need for mica insulation and epoxy/adhesive. The stator and rotor are encased in a stator housing with rear and front end caps, and rear and front bearings for the rotor shaft are mounted on external sides of the end caps to keep debris from the motor migrating into the bearings' races.

  13. Fractography of the high temperature hydrogen attack of a medium carbon steel

    NASA Technical Reports Server (NTRS)

    Melson, H. G.; Moorhead, R. D.

    1975-01-01

    Microscopic fracture processes were studied which are associated with hydrogen attack of a medium carbon steel in a well-controlled, high-temperature, high-purity hydrogen environment. Exposure to a hydrogen pressure and temperature of 3.5 MN/m2 and 575 C was found to degrade room temperature tensile properties with increasing exposure time. After 408 hr, yield and ultimate strengths were reduced by more than 40 percent and elongation was reduced to less than 2 percent. Initial fissure formation was found to be associated with manganese rich particles, most probably manganese oxide, aligned in the microstructure during the rolling operation. Fissure growth was found to be associated with a reduction in carbide content of the microstructure and was inhibited by the depletion of carbon. The interior surfaces of sectioned fissures or bubbles exhibit both primary and secondary cracking by intergranular separation. The grain surfaces were rough and rounded, suggesting a diffusion-associated separation process. Specimens that failed at room temperature after exposure to hydrogen were found to exhibit mixed mode fracture having varying amounts of intergranular separation, dimple formation, and cleavage, depending on exposure time.

  14. Supercritical Water Reactor Cycle for Medium Power Applications

    SciTech Connect

    BD Middleton; J Buongiorno

    2007-04-25

    Scoping studies for a power conversion system based on a direct-cycle supercritical water reactor have been conducted. The electric power range of interest is 5-30 MWe with a design point of 20 MWe. The overall design objective is to develop a system that has minimized physical size and performs satisfactorily over a broad range of operating conditions. The design constraints are as follows: Net cycle thermal efficiency {ge}20%; Steam turbine outlet quality {ge}90%; and Pumping power {le}2500 kW (at nominal conditions). Three basic cycle configurations were analyzed. Listed in order of increased plant complexity, they are: (1) Simple supercritical Rankine cycle; (2) All-supercritical Brayton cycle; and (3) Supercritical Rankine cycle with feedwater preheating. The sensitivity of these three configurations to various parameters, such as reactor exit temperature, reactor pressure, condenser pressure, etc., was assessed. The Thermoflex software package was used for this task. The results are as follows: (a) The simple supercritical Rankine cycle offers the greatest hardware simplification, but its high reactor temperature rise and reactor outlet temperature may pose serious problems from the viewpoint of thermal stresses, stability and materials in the core. (b) The all-supercritical Brayton cycle is not a contender, due to its poor thermal efficiency. (c) The supercritical Rankine cycle with feedwater preheating affords acceptable thermal efficiency with lower reactor temperature rise and outlet temperature. (d) The use of a moisture separator improves the performance of the supercritical Rankine cycle with feedwater preheating and allows for a further reduction of the reactor outlet temperature, thus it was selected for the next step. Preliminary engineering design of the supercritical Rankine cycle with feedwater preheating and moisture separation was performed. All major components including the turbine, feedwater heater, feedwater pump, condenser, condenser pump

  15. Joining of ceramics for high temperature applications

    NASA Technical Reports Server (NTRS)

    Vilpas, Martti

    1987-01-01

    Summarized is a literature survey of the methods for joining ceramics to ceramics or ceramics to metals for high temperature applications. Also mechanical properties and potential applications of the joints are considered. The joining of ceramics is usually carried out by brazing or diffusion bonding. Especially the latter has been found useful, increasing the application of bonded ceramics. The possibility of using electron beam and laser beam welding for joining ceramics has also recently been investigated. The bonding of ceramics has found numerous applications typical for high operating temperatures, i.e., sensors and thermocouples.

  16. Supporting data intensive applications with medium grained parallelism

    SciTech Connect

    Pfaltz, J.L.; French, J.C.; Grimshaw, A.S.; Son, S.H.

    1992-04-01

    ADAMS is an ambitious effort to provide new database access paradigms for the kinds of scientific applications that require massively parallel access to very large data sets in order to be effective. Many of the Grand Challenge Problems fall into this category, as well as those kinds of scientific research which depend on widely distributed shared sets of disparate data. The essence of the ADAMS approach is to view data purely in functional terms, rather than the more traditional structural view in which multiple data items are aggregated into records or tuples of flat files. Further, ADAMS has been implemented as an embedded interface so that scientists can develop applications in the host programming language of their choice, often Fortran, Pascal, or C, and still access shared data generated in other environments. The syntax and semantics of ADAMS is essentially complete. The functional nature of the ADAMS data interface paradigm simplifies its implementation in a distributed environment, e.g., the Mentat run-time system, because one must only distribute functional servers, not pieces of data structures. However, this only opens up the possibility of effective parallel database processing; to realize this potential far more work must be done in the areas of data dependence, intra-statement parallelism, parallel query optimization, and maintaining consistency and reliability in concurrent systems. Discovering how to make effective parallel data access an actually in real scientific applications is the point of this research.

  17. High temperature superconductor materials and applications

    NASA Technical Reports Server (NTRS)

    Doane, George B., III.; Banks, Curtis; Golben, John

    1990-01-01

    Research on processing methods leading to a significant enhancement in the critical current densities (Jc) and the critical temperature (Tc) of high temperature superconducting in thin bulk and thin film forms. The fabrication of important devices for NASA unique applications (sensors) is investigated.

  18. Photoelastic transducer for high-temperature applications

    NASA Technical Reports Server (NTRS)

    Redner, A. S.; Adamovsky, Grigory; Wesson, L. N.

    1990-01-01

    A design for a birefringence transducer for high-temperature applications is described. The spring element and the readout instrumentation are addressed. A pressure transducer based on the concept has been built and successfully tested at temperatures up to 600 C.

  19. Self lubricating composites for medium temperatures in space based on polyimide SINTIMID

    NASA Astrophysics Data System (ADS)

    Merstallinger, A.; Bieringer, H.; Kubinger, E.; Gaillard, L.; Brenner, J.; Mozdzen, G.

    2005-07-01

    The paper is surveying the results of an ESA-project on a polyimide composite named "SINTIMID". The main target was to find a self lubricating composite (SLC) which is suitable for missions to the inner solar system, where operating temperatures up to 300°C in vacuum are expected. The paper comprises a short introduction into the requirements derived from ECSS for SLC material intended for use in journal bearings working in space. It covers a brief description of new equipments for medium temperatures "vacuum tribometer" and "Journal Bearing Test rig". The presented results will cover mainly the friction and wear behaviour and component test performance. The influences of parameters like load, speed, atmosphere and temperature are discussed and compared to other already known materials, e.g. Vespel SP3. The verification procedure included three phases: a screening on several compositions with different fillers and combinations, a detailed friction test campaign on two best compositions (15M and 30M) and a final bush testing on only the best (15M=15w% MoS2). All material properties in relation to ECSS E30 were verified. No objections to the requirements were identified. Finally, a recommendation for design of bushes was set up on the results.

  20. Hybrid solar receiver as a source of high-temperature medium for an absorption chiller supply

    NASA Astrophysics Data System (ADS)

    Przenzak, Estera; Filipowicz, Mariusz

    2016-03-01

    This article discusses the problems related with the cold production, i.e. energy efficiency of the process. The idea of solar cooling systems has been presented as the solution of the problem of big electricity demand. The paper discusses the principle of the operation of absorption chillers. Disadvantages and advantages of the solar cooling systems were discussed. The installation for manufacturing high-temperature heat based on solar collectors and concentrator of solar radiation constructed in AGH in Cracow has been presented. This installation is a first stage of projected, complete solar cooling system. The special attention is paid to the dedicated solar high-temperature heat receiver as a most important element of the system. The achieved values of temperature, power and efficiency depending on the working medium flow has been presented and discussed. The intensity of solar radiation during the measurements has been taken into account. Two versions of heat receiver were investigated: non-insulated and insulated with mineral wool. The obtained efficiency of the heat receiver (less than 30%) is not satisfactory but possibility of improvements exist.

  1. A dynamic synchrotron X-ray imaging study of effective temperature in a vibrated granular medium.

    PubMed

    Cao, Yixin; Zhang, Xiaodan; Kou, Binquan; Li, Xiangting; Xiao, Xianghui; Fezzaa, Kamel; Wang, Yujie

    2014-08-01

    We present a dynamic synchrotron X-ray imaging study of the effective temperature Teff in a vibrated granular medium. By tracking the directed motion and the fluctuation dynamics of the tracers inside, we obtained Teff of the system using the Einstein relationship. We found that as the system unjams with increasing vibration intensities Γ, the structural relaxation time τ increases substantially which can be fitted by an Arrhenius law using Teff. And the characteristic energy scale of structural relaxation yielded by the Arrhenius fitting is E = 0.20 ± 0.02pd(3), where p is the pressure and d is the background particle diameter, which is consistent with those from hard sphere simulations in which the structural relaxation happens via the opening up of free volume against pressure. PMID:24930865

  2. Feasibility study of sulphone-based electrolytes for a medium-temperature reserve cell concept

    NASA Astrophysics Data System (ADS)

    Giwa, C. O.

    This paper describe a feasibility study on material for a medium-temperature (178—270 °C) reserve primary cell, which is activated by melting, lithium salt/sulphone mixture in order to provide electrical power. The aim was to define performance parameters for use as a high energy density battery capable of current density in the range 5 to 50 mA/cm 2. The cathode was silver chromate and vanadium oxide (V 6O 13. The most promising test cell used silver chromate cathode, di- p-tolylsulphone/lithium perchlorate, electrolyte and lithium-aluminium alloy anode. Maximum current capability was 40 mA/cm 2. It was observed that voltage drops were rather high due to the high internal resistance of some sulphone-based cells. These cells around power a heat sensor.

  3. Thermally activated decomposition of (Ga,Mn)As thin layer at medium temperature post growth annealing

    NASA Astrophysics Data System (ADS)

    Melikhov, Y.; Konstantynov, P.; Domagala, J.; Sadowski, J.; Chernyshova, M.; Wojciechowski, T.; Syryanyy, Y.; Demchenko, I. N.

    2016-05-01

    The redistribution of Mn atoms in Ga1-xMnxAs layer during medium-temperature annealing, 250-450 oC, by Mn K-edge X-ray absorption fine structure (XAFS) recorded at ALBA facility, was studied. For this purpose Ga1-xMnxAs thin layer with x=0.01 was grown on AlAs buffer layer deposited on GaAs(100) substrate by molecular beam epitaxy (MBE) followed by annealing. The examined layer was detached from the substrate using a “lift-off” procedure in order to eliminate elastic scattering in XAFS spectra. Fourier transform analysis of experimentally obtained EXAFS spectra allowed to propose a model which describes a redistribution/diffusion of Mn atoms in the host matrix. Theoretical XANES spectra, simulated using multiple scattering formalism (FEFF code) with the support of density functional theory (WIEN2k code), qualitatively describe the features observed in the experimental fine structure.

  4. PAPER-64 Constraints On Reionization. II. The Temperature of the z =8.4 Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    Pober, Jonathan C.; Ali, Zaki S.; Parsons, Aaron R.; McQuinn, Matthew; Aguirre, James E.; Bernardi, Gianni; Bradley, Richard F.; Carilli, Chris L.; Cheng, Carina; DeBoer, David R.; Dexter, Matthew R.; Furlanetto, Steven R.; Grobbelaar, Jasper; Horrell, Jasper; Jacobs, Daniel C.; Klima, Patricia J.; Kohn, Saul A.; Liu, Adrian; MacMahon, David H. E.; Maree, Matthys; Mesinger, Andrei; Moore, David F.; Razavi-Ghods, Nima; Stefan, Irina I.; Walbrugh, William P.; Walker, Andre; Zheng, Haoxuan

    2015-08-01

    We present constraints on both the kinetic temperature of the intergalactic medium (IGM) at z = 8.4, and on models for heating the IGM at high-redshift with X-ray emission from the first collapsed objects. These constraints are derived using a semi-analytic method to explore the new measurements of the 21 cm power spectrum from the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER), which were presented in a companion paper, Ali et al. Twenty-one cm power spectra with amplitudes of hundreds of mK2 can be generically produced if the kinetic temperature of the IGM is significantly below the temperature of the cosmic microwave background (CMB); as such, the new results from PAPER place lower limits on the IGM temperature at z = 8.4. Allowing for the unknown ionization state of the IGM, our measurements find the IGM temperature to be above ≈5 K for neutral fractions between 10% and 85%, above ≈7 K for neutral fractions between 15% and 80%, or above ≈10 K for neutral fractions between 30% and 70%. We also calculate the heating of the IGM that would be provided by the observed high redshift galaxy population, and find that for most models, these galaxies are sufficient to bring the IGM temperature above our lower limits. However, there are significant ranges of parameter space that could produce a signal ruled out by the PAPER measurements; models with a steep drop-off in the star formation rate density at high redshifts or with relatively low values for the X-ray to star formation rate efficiency of high redshift galaxies are generally disfavored. The PAPER measurements are consistent with (but do not constrain) a hydrogen spin temperature above the CMB temperature, a situation which we find to be generally predicted if galaxies fainter than the current detection limits of optical/NIR surveys are included in calculations of X-ray heating.

  5. Space applications of high temperature superconductivity technology

    NASA Technical Reports Server (NTRS)

    Connolly, D. J.; Aron, P. R.; Leonard, R. F.; Wintucky, E. G.

    1991-01-01

    A review is presented of the present status of high temperature superconductivity (HTS) technology and related areas of potential space application. Attention is given to areas of application that include microwave communications, cryogenic systems, remote sensing, and space propulsion and power. Consideration is given to HTS phase shifters, miniaturization of microwave filters, far-IR bolometers, and magnetic refrigeration using flux compression.

  6. Industrial Applications of Low Temperature Plasmas

    SciTech Connect

    Bardsley, J N

    2001-03-15

    The use of low temperature plasmas in industry is illustrated by the discussion of four applications, to lighting, displays, semiconductor manufacturing and pollution control. The type of plasma required for each application is described and typical materials are identified. The need to understand radical formation, ionization and metastable excitation within the discharge and the importance of surface reactions are stressed.

  7. Skin temperatures generated following plaster splint application.

    PubMed

    Lindeque, Bennie G P; Shuler, Franklin D; Bates, Christopher M

    2013-05-01

    Heat is generated during the exothermic reaction associated with plaster splint application. The amount of heat generated is affected by the plaster thickness, dipping water temperature, and extremity elevation method. The authors assessed the effect of these variables on skin and plaster temperatures. Short-leg posterior splints were applied to noninjured extremities on a volunteer using 2 protocols. Following splint application, the splinted leg was elevated in 4 ways: on plastic-covered urethane pillows in cotton pillowcases, on cotton blankets, on ice packs (short-term cryotherapy) placed on top of cotton blankets, or with heel elevation to promote free air circulation. Skin and plaster temperatures were monitored at 1-minute intervals. The maximum skin temperature generated and the average time that skin temperature was 40 °C or higher were recorded. PMID:23672893

  8. Calculation of pressure and temperature in medium-voltage electrical installations due to fault arcs

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Zhang, J.; Gockenbach, E.

    2008-05-01

    In order to determine the pressure rise due to arc faults in electrical installations, the portion of energy heating the surrounding gas of fault arcs has to be known. The ratio of the portion of energy to the electric energy, the thermal transfer coefficient, is adopted as the kp factor. This paper presents a theoretical approach for the determination of the thermal transfer coefficient and the pressure rise in electrical installations. It is based on the fundamental hydro- and thermodynamic conservation equations and the equation of gas state taking into account melting and evaporation of metals as well as chemical reactions with the surrounding gas. In order to consider the dependence of the arc energy on the gas density, the radiative effect of fault arcs on the energy balance is introduced into the arc model by using the net emission coefficient as a function of gas density, arc temperature and arc radius. The results for a test container show that factors such as the kinds of insulating gases and of electrode materials, the size of test vessels and the gas density considerably influence the thermal transfer coefficient and thus the pressure rise. Furthermore, it is demonstrated, for an example of the arc fault in a compact medium-voltage station with pressure relief openings and a pressure relief channel, that the arc energy and the arc temperature can be simulated based on the changing gas density.

  9. Three-dimensionally ordered macroporous iron oxide for removal of H2S at medium temperatures.

    PubMed

    Fan, Hui-Ling; Sun, Ting; Zhao, Yan-Peng; Shangguan, Ju; Lin, Jian-Ying

    2013-05-01

    A series of iron oxide sorbents with novel structures of three-dimensionally ordered macropores (3DOM), ranging in size from 60 to 550 nm, were fabricated and creatively used as sorbents for the removal of H2S at medium temperatures of 300-350 °C. Evaluation tests using thermogravimetric analysis (TGA) and a fixed-bed reactor showed that, in comparison to the iron oxide sorbent prepared by a conventional mixing method, the fabricated iron oxide sorbent with a 3DOM structure exhibited much higher reactivity and efficiency, as well as high sorbent utilization with low regeneration temperature. The excellent performance of 3DOM iron oxide as a sulfur sorbent is attributed to its special texture, i.e., the open and interconnected macroporous, large surface area, and nanoparticles of iron oxide, which are revealed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and nitrogen adsorption techniques. The investigation results of the pore effect on the performance of the sorbent show that sorbents with pores size around 150 nm in diameter revealed the best performance. The reason is that pores of this size are large enough to allow gas to pass through even if the channel is partially blocked during the reaction process while remaining a large surface area that can provide more active sites for the reaction. PMID:23528010

  10. Layering from anticyclonic vortices in a rotating stratified medium with combined salinity and temperature effects

    NASA Astrophysics Data System (ADS)

    Sommeria, Joel; Burin, Michael; Viboud, Samuel

    2015-11-01

    We generate anticyclonic vortices by a fluid source in a rotating and uniformly stratified medium, a laboratory model of long lived vortex lenses in the ocean. Experiments are performed in the large `Coriolis' rotating platform at Grenoble, 13 m in diameter, providing previously unaccessible turbulent regimes. The other novelty is to combine temperature and salinity effects, like in `meddies', vortices formed by intrusion in the Atlantic ocean of warm and salty water from the Mediterranean Sea. For both heated an unheated cases, we observe shear driven instability at the vortex periphery, leading to the emission of material filament from a large-scale m=2 instability. Heated vortices behave much the same way but with two key additions. One, prominent at early times, is that the vortex edge appears serrated around most of its circumference in the upper part of the lens. Two, clearer for later times, a staircase density profile develops above the eddy. We explain this small scale turbulence as thermal convection in the statically unstable density profile resulting from selective vertical diffusion of temperature (while salinity is less diffusive). The resulting turbulent mixing generates horizontal intrusions at the upper part of the vortex, unlike the double-diffusive instability. This work has been funded by Agence Nationale de la Recherche (ANR), project `OLA'.

  11. High performance catalyzed-reaction layer for medium temperature operating solid oxide fuel cells

    SciTech Connect

    Watanabe, M.; Uchida, H.; Shibata, M.; Mochizuki, N.; Amikura, K. . Lab. of Electrochemical Energy Conversion)

    1994-02-01

    New concepts for a high performance catalyzed-reaction layer for medium temperature operating solid oxide fuel cells were proposed. Mixed conducting oxide particles, samaria-doped ceria (SDC), were employed as the anode material utilizing highly dispersed noble metal catalysts on their surface. As the cathode material, Sr-doped LaMnO[sub 3] (LSM) particles catalyzed with microcrystalline Pt were employed. Performances of the anode or cathode were examined in the cell using yttria-stabilized zirconia electrolyte at a series of operating temperatures. It was found that the anodic polarization resistance and its activation energy were greatly decreased by loading only a small amount of the catalysts (such as Ru, Rh, and Pt) onto the SDC particles. The polarization loss at the anode showed a minimum value by using the SDC particles with a mean diameter of 1.5 to 2.0 [mu]m. A large depolarizing effect was also observed with a Pt-catalyzed LSM cathode, especially at high current densities.

  12. Piezoelectric accelerometers for ultrahigh temperature application

    SciTech Connect

    Zhang Shujun; Moses, Paul; Shrout, Thomas R.; Jiang Xiaoning; Lapsley, Michael

    2010-01-04

    High temperature sensors are of major importance to aerospace and energy related industries. In this letter, a high temperature monolithic compression-mode piezoelectric accelerometer was fabricated using YCa{sub 4}O(BO{sub 3}){sub 3} (YCOB) single crystals. The performance of the sensor was tested as function of temperature up to 1000 deg. C and over a frequency range of 100-600 Hz. The accelerometer prototype was found to possess sensitivity of 2.4+-0.4 pC/g, across the measured temperature and frequency range, indicating a low temperature coefficient. Furthermore, the sensor exhibited good stability over an extended dwell time at 900 deg. C, demonstrating that YCOB piezoelectric accelerometers are promising candidates for high temperature sensing applications.

  13. Temperature compensated silicon resonators for space applications

    NASA Astrophysics Data System (ADS)

    Rais-Zadeh, Mina; Thakar, Vikram A.; Wu, Zhengzheng; Peczalski, Adam

    2013-03-01

    This paper presents piezoelectric transduction and frequency trimming of silicon-based resonators with a center frequency in the low megahertz regime. The temperature coefficient of frequency (TCF) of the resonators is reduced using both passive and active compensation schemes. Specifically, a novel technique utilizing oxide-refilled trenches is implemented to achieve efficient temperature compensation while maintaining compatibility with wet release processes. Using this method, we demonstrate high-Q resonators having a first-order TCF as low as 3 ppm/°C and a turnover temperature of around 90 °C, ideally suited for use in ovenized platforms. Using active tuning, the temperature sensitivity of the resonator is further compensated around the turnover temperature, demonstrating frequency instability of less than 400 ppb. Such devices are ideally suited as timing units in space applications where size, power consumption, and temperature stability are of critical importance.

  14. MEMS temperature scanner: principles, advances, and applications

    NASA Astrophysics Data System (ADS)

    Otto, Thomas; Saupe, Ray; Stock, Volker; Gessner, Thomas

    2010-02-01

    Contactless measurement of temperatures has gained enormous significance in many application fields, ranging from climate protection over quality control to object recognition in public places or military objects. Thereby measurement of linear or spatially temperature distribution is often necessary. For this purposes mostly thermographic cameras or motor driven temperature scanners are used today. Both are relatively expensive and the motor drive devices are limited regarding to the scanning rate additionally. An economic alternative are temperature scanner devices based on micro mirrors. The micro mirror, attached in a simple optical setup, reflects the emitted radiation from the observed heat onto an adapted detector. A line scan of the target object is obtained by periodic deflection of the micro scanner. Planar temperature distribution will be achieved by perpendicularly moving the target object or the scanner device. Using Planck radiation law the temperature of the object is calculated. The device can be adapted to different temperature ranges and resolution by using different detectors - cooled or uncooled - and parameterized scanner parameters. With the basic configuration 40 spatially distributed measuring points can be determined with temperatures in a range from 350°C - 1000°C. The achieved miniaturization of such scanners permits the employment in complex plants with high building density or in direct proximity to the measuring point. The price advantage enables a lot of applications, especially new application in the low-price market segment This paper shows principle, setup and application of a temperature measurement system based on micro scanners working in the near infrared range. Packaging issues and measurement results will be discussed as well.

  15. Aerospace applications of high temperature superconductivity

    NASA Technical Reports Server (NTRS)

    Heinen, V. O.; Connolly, D. J.

    1991-01-01

    Space application of high temperature superconducting (HTS) materials may occur before most terrestrial applications because of the passive cooling possibilities in space and because of the economic feasibility of introducing an expensive new technology which has a significant system benefit in space. NASA Lewis Research Center has an ongoing program to develop space technology capitalizing on the potential benefit of HTS materials. The applications being pursued include space communications, power and propulsion systems, and magnetic bearings. In addition, NASA Lewis is pursuing materials research to improve the performance of HTS materials for space applications.

  16. A Chandra Study of Temperature Distributions of the Intracluster Medium in 50 Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Zhu, Zhenghao; Xu, Haiguang; Wang, Jingying; Gu, Junhua; Li, Weitian; Hu, Dan; Zhang, Chenhao; Gu, Liyi; An, Tao; Liu, Chengze; Zhang, Zhongli; Zhu, Jie; Wu, Xiang-Ping

    2016-01-01

    To investigate the spatial distribution of the intracluster medium temperature in galaxy clusters in a quantitative way and probe the physics behind it, we analyze the X-ray spectra from a sample of 50 clusters that were observed with the Chandra ACIS instrument over the past 15 years and measure the radial temperature profiles out to 0.45r500. We construct a physical model that takes into consideration the effects of gravitational heating, thermal history (such as radiative cooling, active galactic nucleus feedback, and thermal conduction), and work done via gas compression, and use it to fit the observed temperature profiles by running Bayesian regressions. The results show that in all cases our model provides an acceptable fit at the 68% confidence level. For further validation, we select nine clusters that have been observed with both Chandra (out to ≳0.3r500) and Suzaku (out to ≳1.5r500) and fit their Chandra spectra with our model. We then compare the extrapolation of the best fits with the Suzaku measurements and find that the model profiles agree with the Suzaku results very well in seven clusters. In the remaining two clusters the difference between the model and the observation is possibly caused by local thermal substructures. Our study also implies that for most of the clusters the assumption of hydrostatic equilibrium is safe out to at least 0.5r500 and the non-gravitational interactions between dark matter and its luminous counterparts is consistent with zero.

  17. Analytical solution of the transient temperature profile in gain medium of passively Q-switched microchip laser.

    PubMed

    Han, Xiahui; Li, Jianlang

    2014-11-01

    The transient temperature evolution in the gain medium of a continuous wave (CW) end-pumped passively Q-switched microchip (PQSM) laser is analyzed. By approximating the time-dependent population inversion density as a sawtooth function of time and treating the time-dependent pump absorption of a CW end-pumped PQSM laser as the superposition of an infinite series of short pumping pulses, the analytical expressions of transient temperature evolution and distribution in the gain medium for four- and three-level laser systems, respectively, are given. These analytical solutions are applied to evaluate the transient temperature evolution and distribution in the gain medium of CW end-pumped PQSM Nd:YAG and Yb:YAG lasers. PMID:25402922

  18. Solar Selective Coatings for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Shumway, Dean A.

    2003-01-01

    Solar selective coatings are envisioned for use on minisatellites, for applications where solar energy is to be used to power heat engines or to provide thermal energy for remote regions in the interior of the spacecraft. These coatings are designed to have the combined properties of high solar absorptance and low infrared emittance. The coatings must be durable at elevated temperatures. For thermal bus applications, the temperature during operation is likely to be near 100 C. For heat engine applications. the temperature is expected to be much greater. The objective of this work was to screen candidate solar selective coatings for their high temperature durability. Candidate solar selective coatings were composed of molecular mixtures of metal and dielectric, including: nickel and aluminum oxide, titanium and aluminum oxide, and platinum and aluminum oxide. To identify high temperature durability, the solar absorptance and infrared emittance of the candidate coatings were evaluated initially, and after heating to temperatures in the range of 400 C to 700 C. The titanium and aluminum oxide molecular mixture was found to be the most durable.

  19. High temperature superconductors for magnetic suspension applications

    NASA Technical Reports Server (NTRS)

    Mcmichael, C. K.; Cooley, R. S.; Chen, Q. Y.; Ma, K. B.; Lamb, M. A.; Meng, R. L.; Chu, C. W.; Chu, W. K.

    1994-01-01

    High temperature superconductors (HTS) hold the promise for applications in magnetic levitation bearings, vibration damping, and torque coupling. Traditional magnetic suspension systems require active feedback and vibration controls in which power consumption and low frequency vibration are among the major engineering concerns. HTS materials have been demonstrated to be an enabling approach towards such problems due to their flux trapping properties. In our laboratory at TCSUH, we have been conducting a series of experiments to explore various mechanical applications using HTS. We have constructed a 30 lb. model flywheel levitated by a hybrid superconducting magnetic bearing (HSMB). We are also developing a levitated and vibration-dampled platform for high precision instrumentation. These applications would be ideal for space usages where ambient temperature is adequate for HTS to operate properly under greatly reduced cryogenic requirements. We will give a general overview of these potential applications and discuss the operating principles of the HTS devices we have developed.

  20. Medium temperature thermal desorption soil remediation case study - Selfridge Air National Guard Base, Mt. Clemens, Michigan

    SciTech Connect

    Flemingloss, K. )

    1994-08-01

    Carlo Environmental Technologies, Inc., (CET) was contracted by the Selfridge Air National Guard base (SANG) to remove an abandoned underground storage tank (UST) farm and remediate the contaminated soil using thermal desorption technology. The first phase of this project was to remove fourteen 25,000 gal underground storage tanks that had been installed during the 1930's, including all ancillary equipment at the facility. The USTs had been used to store aviation fuels, including both av-gas and jet fuels. The tank-removal project disclosed over 5000 yd[sup 3] of contaminated soil in the tank excavation pit, and excavation continued until analytical sampling demonstrated that the perimeter was within the Michigan Department of Natural Resources (MDNR) Act 307 Type B cleanup criteria (state superfund act). The contaminated soil was trucked to a remote location on the base property for the thermal remediation. CET employed its Cedarapids 64MT thermal desorption plant to treat the contaminated soils from the tank removal site. These soils were predominantly clays, and the contamination included BTEX compounds up to 5 parts per million (ppm), and PNA compounds per 100 ppm. The medium temperature thermal desorption process, which heats the contaminated soil to approximately 850[degrees]F was successful in removing BTEX and PNA contamination from the soil (to levels below MDNR Type B cleanup criteria). The vapor stream from the desorption process was then filtered to minimize particulate emissions, and the contaminant compounds were then destroyed in the thermal oxidizer section of the process, at temperatures up to 1800[degrees]F. The remediated soil was returned to the original excavation as clean compacted fill material. With the use of the thermal desorption technology, CET remediated the site to MDNR cleanup standards, recycled the soils from the site, and eliminated off-site disposal liability for SANG.

  1. THE TEMPERATURE-DENSITY RELATION IN THE INTERGALACTIC MEDIUM AT REDSHIFT (z) = 2.4

    SciTech Connect

    Rudie, Gwen C.; Steidel, Charles C.; Pettini, Max

    2012-10-01

    We present new measurements of the temperature-density (T-{rho}) relation for neutral hydrogen in the 2.0 < z < 2.8 intergalactic medium (IGM) using a sample of {approx}6000 individual H I absorbers fitted with Voigt profiles constrained in all cases by multiple Lyman series transitions. We find model-independent evidence for a positive correlation between the column density of H I (N{sub HI}) and the minimum observed velocity width of absorbers (b{sub min}). With minimal interpretation, this implies that the T-{rho} relation in the IGM is not 'inverted', contrary to many recent studies. Fitting b{sub min} as a function of N{sub HI} results in line-width-column-density dependence of the form b{sub min} = b{sub 0}(N{sub HI}/N{sub HI,0}){sup {Gamma}-1} with a minimum line width at mean density ({rho}/{rho}-bar = 1, N{sub HI,0} = 10{sup 13.6} cm{sup -2}) of b{sub 0} = 17.9 {+-} 0.2 km s{sup -1} and a power-law index of ({Gamma} - 1) = 0.15 {+-} 0.02. Using analytic arguments, these measurements imply an 'equation of state' for the IGM at (z) = 2.4 of the form T=T{sub 0} ({rho}/{rho}-bar){sup {gamma}-1} with a temperature at mean density of T{sub 0} = [1.94 {+-} 0.05] Multiplication-Sign 10{sup 4} K and a power-law index ({gamma} - 1) = 0.46 {+-} 0.05.

  2. Limits on the ion temperature anisotropy in the turbulent intracluster medium

    NASA Astrophysics Data System (ADS)

    Santos-Lima, R.; Yan, H.; de Gouveia Dal Pino, E. M.; Lazarian, A.

    2016-08-01

    Turbulence in the weakly collisional intracluster medium (ICM) of galaxies is able to generate strong thermal velocity anisotropies in the ions (with respect to the local magnetic field direction), if the magnetic moment of the particles is conserved in the absence of Coulomb collisions. In this scenario, the anisotropic pressure magnetohydrodynamic (AMHD) turbulence shows a very different statistical behaviour from the standard MHD one and is unable to amplify seed magnetic fields. This is in contrast to previous cosmological MHD simulations that are successful in explaining the observed magnetic fields in the ICM. On the other hand, temperature anisotropies can also drive plasma instabilities that can relax the anisotropy. This work aims to compare the relaxation rate with the growth rate of the anisotropies driven by the turbulence. We employ quasi-linear theory to estimate the ion scattering rate resulting from the parallel firehose, mirror and ion-cyclotron instabilities, for a set of plasma parameters resulting from AMHD simulations of the turbulent ICM. We show that the ICM turbulence can sustain only anisotropy levels very close to the instability thresholds. We argue that the AMHD model that bounds the anisotropies at the marginal stability levels can describe the Alfvénic turbulence cascade in the ICM.

  3. A boron phosphate-phosphoric acid composite membrane for medium temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Mamlouk, M.; Scott, K.

    2015-07-01

    A composite membrane based on a non-stoichiometric composition of BPO4 with excess of PO4 (BPOx) was synthesised and characterised for medium temperature fuel cell use (120-180 °C). The electrolyte was characterised by FTIR, SS-NMR, TGA and XRD and showed that the B-O is tetrahedral, in agreement with reports in the literature that boron phosphorus oxide compounds at B:P < 1 are exclusively built of borate and phosphate tetrahedra. Platinum micro electrodes were used to study the electrolyte compatibility and stability towards oxygen reduction at 150 °C and to obtain kinetic and mass transport parameters. The conductivities of the pure BPOx membrane electrolyte and a Polybenzimidazole (PBI)-4BPOx composite membrane were 7.9 × 10-2 S cm-1 and 4.5 × 10-2 S cm-1 respectively at 150 °C, 5%RH. Fuel cell tests showed a significant enhancement in performance of BPOx over that of typical 5.6H3PO4-PBI membrane electrolyte. The enhancement is due to the improved ionic conductivity (3×), a higher exchange current density of the oxygen reduction (30×) and a lower membrane gas permeability (10×). Fuel cell current densities at 0.6 V were 706 and 425 mA cm-2 for BPOx and 5.6H3PO4-PBI, respectively, at 150 °C with O2 (atm).

  4. 40 CFR 428.60 - Applicability; description of the medium-sized general molded, extruded, and fabricated rubber...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... medium-sized general molded, extruded, and fabricated rubber plants subcategory. 428.60 Section 428.60... (CONTINUED) RUBBER MANUFACTURING POINT SOURCE CATEGORY Medium-Sized General Molded, Extruded, and Fabricated Rubber Plants Subcategory § 428.60 Applicability; description of the medium-sized general...

  5. 40 CFR 428.60 - Applicability; description of the medium-sized general molded, extruded, and fabricated rubber...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... medium-sized general molded, extruded, and fabricated rubber plants subcategory. 428.60 Section 428.60... (CONTINUED) RUBBER MANUFACTURING POINT SOURCE CATEGORY Medium-Sized General Molded, Extruded, and Fabricated Rubber Plants Subcategory § 428.60 Applicability; description of the medium-sized general...

  6. 40 CFR 428.60 - Applicability; description of the medium-sized general molded, extruded, and fabricated rubber...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... medium-sized general molded, extruded, and fabricated rubber plants subcategory. 428.60 Section 428.60... (CONTINUED) RUBBER MANUFACTURING POINT SOURCE CATEGORY Medium-Sized General Molded, Extruded, and Fabricated Rubber Plants Subcategory § 428.60 Applicability; description of the medium-sized general...

  7. Aerospace applications of high temperature superconductivity

    NASA Technical Reports Server (NTRS)

    Connolly, D. J.; Heinen, V. O.; Aron, P. R.; Lazar, J.; Romanofsky, Robert R.

    1990-01-01

    A review is presented of all the applications that are part of the NASA program to develop space technology capitalizing on the potential benefit of high temperature superconducting materials. The applications in three major areas are being pursued: sensors and cryogenic systems, space communications, and propulsion and power systems. This review places emphasis on space communications applications and the propulsion and power applications. It is concluded that the power and propulsion applications will eventually be limited by structural considerations rather than by the availability of suitable superconductors. A cursory examination of structural limitations implied by the virial theorem suggested that there is an upper limit to the size of high field magnetic systems that are feasible in space.

  8. EXCITATION TEMPERATURE OF THE WARM NEUTRAL MEDIUM AS A NEW PROBE OF THE Lyα RADIATION FIELD

    SciTech Connect

    Murray, Claire E.; Lindner, Robert R.; Stanimirović, Snežana; Pingel, Nickolas M.; Lawrence, Allen; Babler, Brian L.; Goss, W. M.; Jencson, Jacob; Heiles, Carl; Dickey, John; Hennebelle, Patrick

    2014-02-01

    We use the Karl G. Jansky Very Large Array to conduct a high-sensitivity survey of neutral hydrogen (H I) absorption in the Milky Way. In combination with corresponding H I emission spectra obtained mostly with the Arecibo Observatory, we detect a widespread warm neutral medium component with excitation temperature 〈T{sub s}〉=7200{sub −1200}{sup +1800} K (68% confidence). This temperature lies above theoretical predictions based on collisional excitation alone, implying that Lyα scattering, the most probable additional source of excitation, is more important in the interstellar medium (ISM) than previously assumed. Our results demonstrate that H I absorption can be used to constrain the Lyα radiation field, a critical quantity for studying the energy balance in the ISM and intergalactic medium yet notoriously difficult to model because of its complicated radiative transfer, in and around galaxies nearby and at high redshift.

  9. WRF-simulated sensitivity to land surface schemes in short and medium ranges for a high-temperature event in East China: A comparative study

    NASA Astrophysics Data System (ADS)

    Zeng, Xin-Min; Wang, Ning; Wang, Yang; Zheng, Yiqun; Zhou, Zugang; Wang, Guiling; Chen, Chaohui; Liu, Huaqiang

    2015-09-01

    We designed simulations for the high-temperature event that occurred on 23 July 2003 in East China using a series of forecast lead times, from short-range to medium-range, and four land surface schemes (LSSs) (i.e., SLAB, NOAH, RUC, and PX) in the Weather Research and Forecasting Model (WRF), Version 3. The sensitivities of short and medium-range simulations to the LSSs systematically varied with the lead times. In general, the model reproduced short-range, high-temperature distributions. The simulated weather was sensitive to the LSSs, and the LSS-induced sensitivity was higher in the medium range than in the short-range. Furthermore, the LSS performances were complex, i.e., the PX errors apparently increased in the medium range (longer than 6 days), RUC produced the maximum errors, and SLAB and NOAH had approximately equivalent errors that slightly increased. Additional sensitivity simulations revealed that the WRF modeling system assigns relatively low initial soil moisture for RUC and that soil moisture initialization plays an important role that is comparable to the LSS choice in the simulations. LSS-induced negative feedback between surface air temperature (SAT) and atmospheric circulation in the lower atmosphere was found in the medium range. These sensitivities were mainly caused by the LSS-induced differences in surface sensible heat flux and by errors associated with the lead times. Using the SAT equation, further diagnostic analyses revealed LSS deficiencies in simulating surface fluxes and physical processes that modify the SAT and indicated the main reasons for these deficiencies. These results have implications for model improvement and application.

  10. Influence of temperature on growth and peak oil biosynthesis in a carbon-limited medium by Pythium irregulare'

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Kinetic analysis was investigated for a carbon-limited medium, with a carbon-to-nitrogen ratio of 5.0, supporting the growth of the 5,8,11,14,17-eicosapentaenoic acid (20:5; omega-3)accumulating fungal organism Pythium irregulare. The productivity and yield parameters at three temperatures, 14, 21, ...

  11. Optimized Perturbation Theory:. Finite Temperature Applications

    NASA Astrophysics Data System (ADS)

    Pinto, Marcus Benghi

    2001-09-01

    We review the optimized perturbation theory (or linear δ-expansion) illustrating with an application to the anharmonic oscillator. We then apply the method to multi-field O(N1) × O(N2) scalar theories at high temperatures to investigate the possibility of inverse symmetry breaking (or symmetry non restoration). Our results support inverse symmetry breaking and reveal the possibility of other high temperature symmetry breaking patterns for which the last term in the breaking sequence is O(N1 - 1) × O(N2 - 1).

  12. Fiber optic temperature sensors for medical applications

    NASA Astrophysics Data System (ADS)

    Schaafsma, David T.; Palmer, Gail; Bechtel, James H.

    2003-07-01

    Recent developments in fiber-optic sensor technology have demonstrated the utility of fiber-optic sensors for both medical and industrial applications. Fiber sensors based on fluorescent decay of rare earth doped materials allow rapid and accurate temperature measurement in challenging environments. Here we review the principles of operation of these sensors with a rare earth doped probe material and demonstrate why this material is an excellent choice for these types of sensors. The decay time technique allows accurate temperature determination from two measurements of the fluorescence intensity at a well-defined time interval. With this method, all instrumental and extraneous environmental effect will cancel, thus providing an accurate temperature measurement. Stability data will be presented for the fiber-optic probes. For medical applications, new breakthroughs in RF ablation technology and electro-surgical procedures are being introduced as alternative, less invasive treatment for removal of small tumors and for removal of plaque within arteries as a preventive treatment that avoids open heart surgery. The availability of small diameter temperature probes (230 microns or 450 microns in diameter) offers a whole new scope to temperature measurement. Accurate and reliable temperature monitoring during any laser treatment procedure or RF ablation at the surgical site is critical. Precise, NIST traceable reliable results are needed to prevent overheating or underheating during treatment. In addition, how interventional catheters are used in hyperthermia studies and the advantages to having flexible cables and multiple sensors are discussed. Preliminary data is given from an animal study where temperature was monitored in a pig during an RF study.

  13. Application of thermal model for pan evaporation to the hydrology of a defined medium, the sponge

    NASA Technical Reports Server (NTRS)

    Trenchard, M. H.; Artley, J. A. (Principal Investigator)

    1981-01-01

    A technique is presented which estimates pan evaporation from the commonly observed values of daily maximum and minimum air temperatures. These two variables are transformed to saturation vapor pressure equivalents which are used in a simple linear regression model. The model provides reasonably accurate estimates of pan evaporation rates over a large geographic area. The derived evaporation algorithm is combined with precipitation to obtain a simple moisture variable. A hypothetical medium with a capacity of 8 inches of water is initialized at 4 inches. The medium behaves like a sponge: it absorbs all incident precipitation, with runoff or drainage occurring only after it is saturated. Water is lost from this simple system through evaporation just as from a Class A pan, but at a rate proportional to its degree of saturation. The contents of the sponge is a moisture index calculated from only the maximum and minium temperatures and precipitation.

  14. Influence of the Refractivity and Temperature of the Ambient Medium on the Eigenfrequencies of Quasioptical Cylindrical Dielectric Resonators

    NASA Astrophysics Data System (ADS)

    Dormidontov, A. V.; Prokopenko, Yu. V.

    2013-11-01

    We attempt for the first time to separate the influences of the temperature and refractivity of the ambient air space on the spectral and energy characteristics of cylindrical Teflon and leucosapphire resonators with the whispering gallery modes in the millimeter-wave range. It is found that under conditions of natural fluctuations of the above-mentioned factors of the studied ambient medium, the degree of temperature influence on the resonator eigenfrequencies is more significant. We demonstrate that quasioptical cylindrical dielectric resonators can be used as sensors of the temperature of the ambient air medium and ensure an accuracy of 10-4°C when their resonant frequencies are measured with an accuracy of 100 Hz. A method for determination of the air refractivity has been developed, which uses the considered resonator as a temperature sensor and a measuring cell of the microwave resonator refractometer. A refractometer sensor has been developed on the basis of two identical resonators with whispering gallery modes. The differential two-resonator refractometer compensates for the influence of changes in the temperature of the ambient medium on the measured difference of the eigenfrequencies of resonators with identical modes. It is found that the accuracy of determination of the air refractivity is ensured at a level of 10-2 if the frequency difference is measured with an accuracy of 10 Hz.

  15. Effects of fluid medium flow and spatial temperature variation on acoustophoretic motion of microparticles in microfluidic channels.

    PubMed

    Liu, Zhongzheng; Kim, Yong-Joe; Wang, Han; Han, Arum

    2016-01-01

    A numerical modeling method for accurately predicting the acoustophoretic motion of compressible microparticles in microfluidic devices is presented to consider the effects of fluid medium flow and spatial temperature variation that can significantly influence the acoustophoretic motion. In the proposed method, zeroth-order fluid medium flow and temperature, and first- and second-order acoustic fields in the microfluidic devices are first calculated by applying quadratic mapping functions and a second-order finite difference method (FDM) to perturbed mass, momentum, and energy conservation equations and state equation. Then, the acoustic radiation force is obtained based on the Gorkov's acoustic radiation force equation and applied to the Newton's Equation of Motion to calculate the microparticle motion. The proposed method was validated by comparing its results to a commercial software package, COMSOL Multiphysics results, one-dimensional, analytical modeling results, and experimental results. It is shown that the fluid medium flow affects the acoustic radiation force and streaming significantly, resulting in the acoustic radiation force and streaming prediction errors of 10.9% and 67.4%, respectively, when the fluid medium flow speed is increased from 0 to 1 m/s. A local temperature elevation from 20 °C to 22 °C also results in the prediction errors of 88.4% and 73.4%. PMID:26827029

  16. Medium factors on anaerobic production of rhamnolipids by Pseudomonas aeruginosa SG and a simplifying medium for in situ microbial enhanced oil recovery applications.

    PubMed

    Zhao, Feng; Zhou, Jidong; Han, Siqin; Ma, Fang; Zhang, Ying; Zhang, Jie

    2016-04-01

    Aerobic production of rhamnolipid by Pseudomonas aeruginosa was extensively studied. But effect of medium composition on anaerobic production of rhamnolipid by P. aeruginosa was unknown. A simplifying medium facilitating anaerobic production of rhamnolipid is urgently needed for in situ microbial enhanced oil recovery (MEOR). Medium factors affecting anaerobic production of rhamnolipid were investigated using P. aeruginosa SG (Genbank accession number KJ995745). Medium composition for anaerobic production of rhamnolipid by P. aeruginosa is different from that for aerobic production of rhamnolipid. Both hydrophobic substrate and organic nitrogen inhibited rhamnolipid production under anaerobic conditions. Glycerol and nitrate were the best carbon and nitrogen source. The commonly used N limitation under aerobic conditions was not conducive to rhamnolipid production under anaerobic conditions because the initial cell growth demanded enough nitrate for anaerobic respiration. But rhamnolipid was also fast accumulated under nitrogen starvation conditions. Sufficient phosphate was needed for anaerobic production of rhamnolipid. SO4(2-) and Mg(2+) are required for anaerobic production of rhamnolipid. Results will contribute to isolation bacteria strains which can anaerobically produce rhamnolipid and medium optimization for anaerobic production of rhamnolipid. Based on medium optimization by response surface methodology and ions composition of reservoir formation water, a simplifying medium containing 70.3 g/l glycerol, 5.25 g/l NaNO3, 5.49 g/l KH2PO4, 6.9 g/l K2HPO4·3H2O and 0.40 g/l MgSO4 was designed. Using the simplifying medium, 630 mg/l of rhamnolipid was produced by SG, and the anaerobic culture emulsified crude oil to EI24 = 82.5 %. The simplifying medium was promising for in situ MEOR applications. PMID:26925616

  17. Application of a medium-range global hydrologic probabilistic forecast scheme to the Ohio River Basin

    SciTech Connect

    Voisin, Nathalie; Pappenberger, Florian; Lettenmaier, D. P.; Buizza, Roberto; Schaake, John

    2011-08-15

    A 10-day globally applicable flood prediction scheme was evaluated using the Ohio River basin as a test site for the period 2003-2007. The Variable Infiltration Capacity (VIC) hydrology model was initialized with the European Centre for Medium Range Weather Forecasts (ECMWF) analysis temperatures and wind, and Tropical Rainfall Monitoring Mission Multi Satellite Precipitation Analysis (TMPA) precipitation up to the day of forecast. In forecast mode, the VIC model was then forced with a calibrated and statistically downscaled ECMWF ensemble prediction system (EPS) 10-day ensemble forecast. A parallel set up was used where ECMWF EPS forecasts were interpolated to the spatial scale of the hydrology model. Each set of forecasts was extended by 5 days using monthly mean climatological variables and zero precipitation in order to account for the effect of initial conditions. The 15-day spatially distributed ensemble runoff forecasts were then routed to four locations in the basin, each with different drainage areas. Surrogates for observed daily runoff and flow were provided by the reference run, specifically VIC simulation forced with ECMWF analysis fields and TMPA precipitation fields. The flood prediction scheme using the calibrated and downscaled ECMWF EPS forecasts was shown to be more accurate and reliable than interpolated forecasts for both daily distributed runoff forecasts and daily flow forecasts. Initial and antecedent conditions dominated the flow forecasts for lead times shorter than the time of concentration depending on the flow forecast amounts and the drainage area sizes. The flood prediction scheme had useful skill for the 10 following days at all sites.

  18. Aerospace Applications Of High Temperature Superconductivity

    NASA Astrophysics Data System (ADS)

    Anderson, W. W.

    1988-05-01

    The existence of superconductors with TcOOK (which implies device operating temper-atures the order of Top ≍45K) opens up a variety of potential applications within the aerospace/defense industry. This is partly due to the existence of well developed cooler technologies to reach this temperature regime and partly due to the present operation of some specialized components at cryogenic temperatures. In particular, LWIR focal planes may operate at 10K with some of the signal processing electronics at an intermediate temperature of 40K. Addition of high Tc superconducting components in the latter system may be "free" in the sense of additional system complexity required. The established techniques for cooling in the 20K to 50K temperature regime are either open cycle, expendable material (stored gas with Joule-Thomson expansion, liquid cryogen or solid cryogen) or mechanical refrigerators (Stirling cycle, Brayton cycle or closed cycle Joule-Thomson). The high Tc materials may also contribute to the development of coolers through magnetically levitated bearings or providing the field for a stage of magnetic refrigeration. The discovery of materials with Tc, 90K has generated a veritable shopping list of applications. The superconductor properties which are of interest for applications are (1) zero resistance, (2) Meissner effect, (3) phase coherence and (4) existence of an energy gap. The zero resistance property is significant in the development of high field magnets requiring neglible power to maintain the field. In addition to the publicized applications to rail guns and electromagnetic launcher, we can think of space born magnets for charged particle shielding or whistler mode propagation through a plasma sheath. Conductor losses dominate attenuation and dispersion in microstrip transmission lines. While the surface impedance of a superconductor is non vanishing, significant improvements in signal transmission may be obtained. The Meissner effect may be utilized

  19. High temperature superconductors applications in telecommunications

    NASA Technical Reports Server (NTRS)

    Kumar, A. Anil; Li, Jiang; Zhang, Ming Fang

    1995-01-01

    The purpose of this paper is twofold: (1) to discuss high temperature superconductors with specific reference to their employment in telecommunications applications; and (2) to discuss a few of the limitations of the normally employed two-fluid model. While the debate on the actual usage of high temperature superconductors in the design of electronic and telecommunications devices - obvious advantages versus practical difficulties - needs to be settled in the near future, it is of great interest to investigate the parameters and the assumptions that will be employed in such designs. This paper deals with the issue of providing the microwave design engineer with performance data for such superconducting waveguides. The values of conductivity and surface resistance, which are the primary determining factors of a waveguide performance, are computed based on the two-fluid model. A comparison between two models - a theoretical one in terms of microscopic parameters (termed Model A) and an experimental fit in terms of macroscopic parameters (termed Model B) - shows the limitations and the resulting ambiguities of the two-fluid model at high frequencies and at temperatures close to the transition temperature. The validity of the two-fluid model is then discussed. Our preliminary results show that the electrical transport description in the normal and superconducting phases as they are formulated in the two-fluid model needs to be modified to incorporate the new and special features of high temperature superconductors. Parameters describing the waveguide performance - conductivity, surface resistance and attenuation constant - will be computed. Potential applications in communications networks and large scale integrated circuits will be discussed. Some of the ongoing work will be reported. In particular, a brief proposal is made to investigate of the effects of electromagnetic interference and the concomitant notion of electromagnetic compatibility (EMI/EMC) of high T

  20. High temperature superconductors applications in telecommunications

    SciTech Connect

    Kumar, A.A.; Li, J.; Zhang, M.F.

    1994-12-31

    The purpose of this paper is twofold: to discuss high temperature superconductors with specific reference to their employment in telecommunications applications; and to discuss a few of the limitations of the normally employed two-fluid model. While the debate on the actual usage of high temperature superconductors in the design of electronic and telecommunications devices-obvious advantages versus practical difficulties-needs to be settled in the near future, it is of great interest to investigate the parameters and the assumptions that will be employed in such designs. This paper deals with the issue of providing the microwave design engineer with performance data for such superconducting waveguides. The values of conductivity and surface resistance, which are the primary determining factors of a waveguide performance, are computed based on the two-fluid model. A comparison between two models-a theoretical one in terms of microscopic parameters (termed Model A) and an experimental fit in terms of macroscopic parameters (termed Model B)-shows the limitations and the resulting ambiguities of the two-fluid model at high frequencies and at temperatures close to the transition temperature. The validity of the two-fluid model is then discussed. Our preliminary results show that the electrical transport description in the normal and superconducting phases as they are formulated in the two-fluid model needs to be modified to incorporate the new and special features of high temperature superconductors. Parameters describing the waveguide performance-conductivity, surface resistance and attenuation constant-will be computed. Potential applications in communications networks and large scale integrated circuits will be discussed. Some of the ongoing work will be reported. In particular, a brief proposal is made to investigate of the effects of electromagnetic interference and the concomitant notion of electromagnetic compatibility (EMI/EMC) of high T{sub c} superconductors.

  1. High Temperature Battery for Drilling Applications

    SciTech Connect

    Josip Caja

    2009-12-31

    In this project rechargeable cells based on the high temperature electrochemical system Na/beta''-alumina/S(IV) in AlCl3/NaCl were developed for application as an autonomous power source in oil/gas deep drilling wells. The cells operate in the temperature range from 150 C to 250 C. A prototype DD size cell was designed and built based on the results of finite element analysis and vibration testing. The cell consisted of stainless steel case serving as anode compartment with cathode compartment installed in it and a seal closing the cell. Critical element in cell design and fabrication was hermetically sealing the cell. The seal had to be leak tight, thermally and vibration stable and compatible with electrode materials. Cathode compartment was built of beta''-alumina tube which served as an electrolyte, separator and cathode compartment.

  2. Application of Medium and Seasonal Flood Forecasts for Agriculture Damage Assessment

    NASA Astrophysics Data System (ADS)

    Fakhruddin, Shamsul; Ballio, Francesco; Menoni, Scira

    2015-04-01

    Early warning is a key element for disaster risk reduction. In recent decades, major advancements have been made in medium range and seasonal flood forecasting. This progress provides a great opportunity to reduce agriculture damage and improve advisories for early action and planning for flood hazards. This approach can facilitate proactive rather than reactive management of the adverse consequences of floods. In the agricultural sector, for instance, farmers can take a diversity of options such as changing cropping patterns, applying fertilizer, irrigating and changing planting timing. An experimental medium range (1-10 day) and seasonal (20-25 days) flood forecasting model has been developed for Thailand and Bangladesh. It provides 51 sets of discharge ensemble forecasts of 1-10 days with significant persistence and high certainty and qualitative outlooks for 20-25 days. This type of forecast could assist farmers and other stakeholders for differential preparedness activities. These ensembles probabilistic flood forecasts have been customized based on user-needs for community-level application focused on agriculture system. The vulnerabilities of agriculture system were calculated based on exposure, sensitivity and adaptive capacity. Indicators for risk and vulnerability assessment were conducted through community consultations. The forecast lead time requirement, user-needs, impacts and management options for crops were identified through focus group discussions, informal interviews and community surveys. This paper illustrates potential applications of such ensembles for probabilistic medium range and seasonal flood forecasts in a way that is not commonly practiced globally today.

  3. Evaporation of a water drop with a solid opaque inclusion moving through a high-temperature gaseous medium

    NASA Astrophysics Data System (ADS)

    Antonov, D. V.; Volkov, R. S.; Piskunov, M. V.; Strizhak, P. A.

    2016-03-01

    The process of evaporation of an inhomogeneous (containing a graphite particle) water drop moving through a high-temperature (about 1100 K) gas medium has been experimentally studied using highspeed (no less than 105 fps) video recording tools, the PIV scanning optical method, and Tema Automotive software. The influences of the ratio of water and inclusion masses, shape of inclusion (by the example of cylindrical disk, cube, and parallelepiped), and its surface area on the integral characteristics of liquid evaporation when heterogeneous drops are passed through a channel (length 1 m, inner diameter 0.2 m) with high-temperature gases are established.

  4. Potential aerospace applications of high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Selim, Raouf

    1994-12-01

    The recent discovery of High Temperature Superconductors (HTS) with superconducting transition temperature, T(sub c), above the boiling point of liquid nitrogen has opened the door for using these materials in new and practical applications. These materials have zero resistance to electric current, have the capability of carrying large currents and as such have the potential to be used in high magnetic field applications. One of the space applications that can use superconductors is electromagnetic launch of payloads to low-earth-orbit. An electromagnetic gun-type launcher can be used in small payload systems that are launched at very high velocity, while sled-type magnetically levitated launcher can be used to launch larger payloads at smaller velocities. Both types of launchers are being studied by NASA and the aerospace industry. The use of superconductors will be essential in any of these types of launchers in order to produce the large magnetic fields required to obtain large thrust forces. Low Temperature Superconductor (LTS) technology is mature enough and can be easily integrated in such systems. As for the HTS, many leading companies are currently producing HTS coils and magnets that potentially can be mass-produced for these launchers. It seems that designing and building a small-scale electromagnetic launcher is the next logical step toward seriously considering this method for launching payloads into low-earth-orbit. A second potential application is the use of HTS to build sensitive portable devices for the use in Non Destructive Evaluation (NDE). Superconducting Quantum Interference Devices (SQUID's) are the most sensitive instruments for measuring changes in magnetic flux. By using HTS in SQUID's, one will be able to design a portable unit that uses liquid nitrogen or a cryocooler pump to explore the use of gradiometers or magnetometers to detect deep cracks or corrosion in structures. A third use is the replacement of Infra-Red (IR) sensor leads on

  5. Potential aerospace applications of high temperature superconductors

    NASA Technical Reports Server (NTRS)

    Selim, Raouf

    1994-01-01

    The recent discovery of High Temperature Superconductors (HTS) with superconducting transition temperature, T(sub c), above the boiling point of liquid nitrogen has opened the door for using these materials in new and practical applications. These materials have zero resistance to electric current, have the capability of carrying large currents and as such have the potential to be used in high magnetic field applications. One of the space applications that can use superconductors is electromagnetic launch of payloads to low-earth-orbit. An electromagnetic gun-type launcher can be used in small payload systems that are launched at very high velocity, while sled-type magnetically levitated launcher can be used to launch larger payloads at smaller velocities. Both types of launchers are being studied by NASA and the aerospace industry. The use of superconductors will be essential in any of these types of launchers in order to produce the large magnetic fields required to obtain large thrust forces. Low Temperature Superconductor (LTS) technology is mature enough and can be easily integrated in such systems. As for the HTS, many leading companies are currently producing HTS coils and magnets that potentially can be mass-produced for these launchers. It seems that designing and building a small-scale electromagnetic launcher is the next logical step toward seriously considering this method for launching payloads into low-earth-orbit. A second potential application is the use of HTS to build sensitive portable devices for the use in Non Destructive Evaluation (NDE). Superconducting Quantum Interference Devices (SQUID's) are the most sensitive instruments for measuring changes in magnetic flux. By using HTS in SQUID's, one will be able to design a portable unit that uses liquid nitrogen or a cryocooler pump to explore the use of gradiometers or magnetometers to detect deep cracks or corrosion in structures. A third use is the replacement of Infra-Red (IR) sensor leads on

  6. Theoretical fast non-intrusive 3-D temperature distribution measurement within scattering medium from flame emission image analysis

    NASA Astrophysics Data System (ADS)

    Huang, Qun-xing; Yan, Fei Wang Jian-hua; Chi, Yong

    2013-04-01

    A new approach to inverse radiation analysis is presented for non-intrusive 3-D flame temperature reconstruction using flame emission images from four CCD camera detectors installed on the furnace wall. The scattering from participating medium in the flame was considered by combining the discrete radiative transfer method with the discrete ordinate method. A modified minimum residual algorithm was employed to calculate the least squares solution of the ill-conditioned inverse problem. A numerical test problem simulating real temperature measurements in an industrial furnace was used to assess the performance of the proposed method. These assessments indicate that this method is capable of reconstructing 3-D temperature distributions fast and accurately, even with noisy flame emission data. Such a capability has potential in real-time temperature measurement for combustion optimization and pollution emission control.

  7. 40 CFR 428.60 - Applicability; description of the medium-sized general molded, extruded, and fabricated rubber...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... medium-sized general molded, extruded, and fabricated rubber plants subcategory. 428.60 Section 428.60... RUBBER MANUFACTURING POINT SOURCE CATEGORY Medium-Sized General Molded, Extruded, and Fabricated Rubber... fabricated rubber plants subcategory. The following provisions of this subpart are applicable to...

  8. 40 CFR 428.60 - Applicability; description of the medium-sized general molded, extruded, and fabricated rubber...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... medium-sized general molded, extruded, and fabricated rubber plants subcategory. 428.60 Section 428.60... RUBBER MANUFACTURING POINT SOURCE CATEGORY Medium-Sized General Molded, Extruded, and Fabricated Rubber... fabricated rubber plants subcategory. The following provisions of this subpart are applicable to...

  9. Application of a mobile medium voltage sub-cycle transfer switch

    SciTech Connect

    Doncker, R.W. de; Maranto, J.A.

    1996-11-01

    This paper presents the application of a Mobile 3{O} Medium Voltage Sub-Cycle Transfer Switch (MVSTS). This application is a 15 kV class witch rated at a continuous current of 600 A. The function of a sub-cycle switch is to maintain AC electrical power to a critical load by switching between 2 independent sources within 4 ms. This switching time is sufficiently fast to preserve the operation of even the most sensitive customer equipment loads during distribution system disturbances such as voltage sags or swells. The mobile unit will allow a quick installation to a customer`s facility for temporary reliability assurance in a Preferred/Alternate or Split-Bus arrangement. This application also gives a customer the flexibility of trying the MVSTS before committing to a permanent installation.

  10. 46 CFR 57.05-5 - Low temperature application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Low temperature application. 57.05-5 Section 57.05-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING WELDING AND BRAZING Performance Qualifications § 57.05-5 Low temperature application. For low temperature application, each...

  11. 46 CFR 57.05-5 - Low temperature application.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Low temperature application. 57.05-5 Section 57.05-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING WELDING AND BRAZING Performance Qualifications § 57.05-5 Low temperature application. For low temperature application, each...

  12. 46 CFR 57.05-5 - Low temperature application.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Low temperature application. 57.05-5 Section 57.05-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING WELDING AND BRAZING Performance Qualifications § 57.05-5 Low temperature application. For low temperature application, each...

  13. 46 CFR 57.05-5 - Low temperature application.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Low temperature application. 57.05-5 Section 57.05-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING WELDING AND BRAZING Performance Qualifications § 57.05-5 Low temperature application. For low temperature application, each...

  14. 46 CFR 57.05-5 - Low temperature application.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Low temperature application. 57.05-5 Section 57.05-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING WELDING AND BRAZING Performance Qualifications § 57.05-5 Low temperature application. For low temperature application, each...

  15. Applicability of the effective-medium approximation to heterogeneous aerosol particles

    NASA Astrophysics Data System (ADS)

    Mishchenko, Michael I.; Dlugach, Janna M.; Liu, Li

    2016-07-01

    The effective-medium approximation (EMA) is based on the assumption that a heterogeneous particle can have a homogeneous counterpart possessing similar scattering and absorption properties. We analyze the numerical accuracy of the EMA by comparing superposition T-matrix computations for spherical aerosol particles filled with numerous randomly distributed small inclusions and Lorenz-Mie computations based on the Maxwell-Garnett mixing rule. We verify numerically that the EMA can indeed be realized for inclusion size parameters smaller than a threshold value. The threshold size parameter depends on the refractive-index contrast between the host and inclusion materials and quite often does not exceed several tenths, especially in calculations of the scattering matrix and the absorption cross section. As the inclusion size parameter approaches the threshold value, the scattering-matrix errors of the EMA start to grow with increasing the host size parameter and/or the number of inclusions. We confirm, in particular, the existence of the effective-medium regime in the important case of dust aerosols with hematite or air-bubble inclusions, but then the large refractive-index contrast necessitates inclusion size parameters of the order of a few tenths. Irrespective of the highly restricted conditions of applicability of the EMA, our results provide further evidence that the effective-medium regime must be a direct corollary of the macroscopic Maxwell equations under specific assumptions.

  16. A new medium for triplet-triplet annihilated upconversion and photocatalytic application.

    PubMed

    Ye, Changqing; Wang, Jingjing; Wang, Xiaomei; Ding, Ping; Liang, Zuoqin; Tao, Xutang

    2016-02-01

    Since the triplet-triplet annihilated upconversion (TTA-UC) materials work efficiently only in degassing organic solvents, it is of significance to find a new medium without toxicity and volatility and that promotes TTA-UC. Here, we firstly reported the effect of an OH-containing medium on low power upconversion and found that in alcohol solvent containing β-cyclodextrin (β-CD), the phosphorescence lifetime (τp) of the sensitizer (PdTPP) and the fluorescence quantum yield (Φf) of the acceptor (DPA) were enhanced with the increase in the number of OH-groups of the medium. A large triplet-triplet quenching constant (kq, 1.91 × 10(9) M(-1) s(-1)) and high upconversion efficiency (ΦUC, ∼ 36%) of PdTPP/DPA were obtained under the excitation of a diode laser (532 nm, 60 mW cm(-2)). Under our green-to-blue upconversion irradiation, in a demonstration experiment the photocurrent was recorded at 0.09 μA cm(-2), resulting from photocatalytic water splitting by a Cd0.7Zn0.3S photoanode and a Pt counter-electrode in a photoelectrochemical cell. The importance of this study suggests that upconversion-powered photoelectrochemistry possesses potential application for hydrogen generation from water under excitation of sun energy. PMID:26580451

  17. [Application of optimization management model of municipal solid waste from medium or small city of China].

    PubMed

    Li, Tianwei; Yan, Gang; Wang, Yeyao; Ma, Xiaofan; Nie, Yongfeng

    2003-05-01

    According to the basic characteristics of municipal solid waste generated from medium or small city of China, the optimal management principles and programs for optimization management model suitable to them were put forward. By application of the model in case study, the optimal scenarios for the disposal of municipal solid waste from the planning system in 1999, 2005 and 2010 were calculated, which adequately validated and accounted for the advantages of optimization model by comparison of costs between optimization scenarios and former scenarios. PMID:12916219

  18. Impact of porous medium on the high cycle temperature fluctuations in a mixing tee

    SciTech Connect

    Bu, L.; Zhao, J.

    2012-07-01

    Temperature fluctuations occur in the region where hot and cold fluids mix turbulently in the nuclear power plants. Temperature fluctuations cause thermal fatigue of piping systems. In the design of generation IV nuclear power plants, supercritical fluids are supposed to be used widely. This paper investigated the thermal striping phenomenon caused by the turbulent mixing in a supercritical water Tee. There are two key issues in the study of thermal striping phenomenon: One is to find the region which experiences the peak temperature fluctuation; the other is how to attenuate it. Porous media was used to attenuate the temperature fluctuations in this paper. The results show that porous media with proper parameters in a tee can reduce the temperature fluctuations magnificently. (authors)

  19. Effects of Wall Shear Stress on Unsteady MHD Conjugate Flow in a Porous Medium with Ramped Wall Temperature

    PubMed Central

    Khan, Arshad; Khan, Ilyas; Ali, Farhad; ulhaq, Sami; Shafie, Sharidan

    2014-01-01

    This study investigates the effects of an arbitrary wall shear stress on unsteady magnetohydrodynamic (MHD) flow of a Newtonian fluid with conjugate effects of heat and mass transfer. The fluid is considered in a porous medium over a vertical plate with ramped temperature. The influence of thermal radiation in the energy equations is also considered. The coupled partial differential equations governing the flow are solved by using the Laplace transform technique. Exact solutions for velocity and temperature in case of both ramped and constant wall temperature as well as for concentration are obtained. It is found that velocity solutions are more general and can produce a huge number of exact solutions correlative to various fluid motions. Graphical results are provided for various embedded flow parameters and discussed in details. PMID:24621775

  20. Generalized Thermoelastic Medium with Temperature-Dependent Properties for Different Theories under the Effect of Gravity Field

    NASA Astrophysics Data System (ADS)

    Othman, Mohamed I. A.; Elmaklizi, Yassmin D.; Said, Samia M.

    2013-03-01

    The problem of the generalized thermoelastic medium for three different theories under the effect of a gravity field is investigated. The Lord-Shulman (L-S), Green-Lindsay (G-L), and classical-coupled (CD) theories are discussed. The modulus of the elasticity is given as a linear function of the reference temperature. The exact expressions for the displacement components, temperature, and stress components are obtained by using normal mode analysis. Numerical results for the field quantities are given in the physical domain and illustrated graphically in the absence and presence of gravity. A comparison also is made between the three theories for the results with and without a temperature dependence.

  1. Magnetic refrigeration for low-temperature applications

    NASA Technical Reports Server (NTRS)

    Barclay, J. A.

    1985-01-01

    The application of refrigeration at low temperatures ranging from production of liquid helium for medical imaging systems to cooling of infrared sensors on surveillance satellites is discussed. Cooling below about 15 K with regenerative refrigerators is difficult because of the decreasing thermal mass of the regenerator compared to that of the working material. In order to overcome this difficulty with helium gas as the working material, a heat exchanger plus a Joule-Thomson or other exponder is used. Regenerative magnetic refrigerators with magnetic solids as the working material have the same regenerator problem as gas refrigerators. This problem provides motivation for the development of nonregenerative magnetic refrigerators that span approximately 1 K to approximately 0 K. Particular emphasis is placed on high reliability and high efficiency. Calculations indicate considerable promise in this area. The principles, the potential, the problems, and the progress towards development of successful 4 to 20 K magnetic refrigerators are discussed.

  2. Cast Aluminum Alloy for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2003-01-01

    Originally developed by NASA as high performance piston alloys to meet U.S. automotive legislation requiring low exhaust emission, the novel NASA alloys now offer dramatic increase in tensile strength for many other applications at elevated temperatures from 450 F (232 C) to about 750 F (400 C). It is an ideal low cost material for cast automotive components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. It can be very economically produced from conventional permanent mold, sand casting or investment casting, with silicon content ranging from 6% to 18%. At high silicon levels, the alloy exhibits excellent dimensional stability, surface hardness and wear resistant properties.

  3. High Temperature Solid Lubricant Coating for High Temperature Wear Applications

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher (Inventor); Edmonds, Brian J (Inventor)

    2014-01-01

    A self-lubricating, friction and wear reducing composite useful over a wide temperature range is described herein. The composite includes metal bonded chromium oxide dispersed in a metal binder having a substantial amount of nickel. The composite contains a fluoride of at least one Group I, Group II, or rare earth metal, and optionally a low temperature lubricant metal.

  4. Statistical medium optimization of an alkaline protease from Pseudomonas aeruginosa MTCC 10501, its characterization and application in leather processing.

    PubMed

    Boopathy, Naidu Ramachandra; Indhuja, Devadas; Srinivasan, Krishnan; Uthirappan, Mani; Gupta, Rishikesh; Ramudu, Kamini Numbi; Chellan, Rose

    2013-04-01

    Proteases are shown to have greener mode of application in leather processing for dehairing of goat skins and cow hides. Production of protease by submerged fermentation with potent activity is reported using a new isolate P. aeruginosa MTCC 10501. The production parameters were optimized by statistical methods such as Plackett-Burman and response surface methodology. The optimized production medium contained (g/L); tryptone, 2.5; yeast extract, 3.0; skim milk 30.0; dextrose 1.0; inoculum concentration 4%: initial pH 6.0; incubation temperature 30 degrees C and optimum production at 48 h with protease activity of 7.6 U/mL. The protease had the following characteristics: pH optima, 9.0; temperature optima 50 degrees C; pH stability between 5.0-10.0 and temperature stability between 10-40 degrees C. The protease was observed to have high potential for dehairing of goat skins in the pre- tanning process comparable to that of the chemical process as evidenced by histology. The method offers cleaner processing using enzyme only instead of toxic chemicals in the pre-tanning process of leather manufacture. PMID:24195353

  5. Low temperature formation of naphthalene and its role in the synthesis of PAHs (Polycyclic Aromatic Hydrocarbons) in the interstellar medium

    PubMed Central

    Zhang, Fangtong; Kim, Y. Seol; Kaiser, Ralf I.; Landera, Alexander; Kislov, Vadim V.; Mebel, Alexander M.; Tielens, A. G. G. M.

    2012-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are regarded as key molecules in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest prototype—naphthalene (C10H8)—has remained an open question. Here, we show in a combined crossed beam and theoretical study that naphthalene can be formed in the gas phase via a barrierless and exoergic reaction between the phenyl radical (C6H5) and vinylacetylene (CH2 = CH-C ≡ CH) involving a van-der-Waals complex and submerged barrier in the entrance channel. Our finding challenges conventional wisdom that PAH-formation only occurs at high temperatures such as in combustion systems and implies that low temperature chemistry can initiate the synthesis of the very first PAH in the interstellar medium. In cold molecular clouds, barrierless phenyl-type radical reactions could propagate the vinylacetylene-mediated formation of PAHs leading to more complex structures like phenanthrene and anthracene at temperatures down to 10 K. PMID:22198769

  6. Ultrasonic tomography for in-process measurements of temperature in a multi-phase medium

    DOEpatents

    Beller, Laurence S.

    1993-01-01

    A method and apparatus for the in-process measurement of internal particulate temperature utilizing ultrasonic tomography techniques to determine the speed of sound through a specimen material. Ultrasonic pulses are transmitted through a material, which can be a multi-phase material, over known flight paths and the ultrasonic pulse transit times through all sectors of the specimen are measured to determine the speed of sound. The speed of sound being a function of temperature, it is possible to establish the correlation between speed of sound and temperature, throughout a cross-section of the material, which correlation is programmed into a computer to provide for a continuous in-process measurement of temperature throughout the specimen.

  7. Ultrasonic tomography for in-process measurements of temperature in a multi-phase medium

    DOEpatents

    Beller, L.S.

    1993-01-26

    A method and apparatus are described for the in-process measurement of internal particulate temperature utilizing ultrasonic tomography techniques to determine the speed of sound through a specimen material. Ultrasonic pulses are transmitted through a material, which can be a multi-phase material, over known flight paths and the ultrasonic pulse transit times through all sectors of the specimen are measured to determine the speed of sound. The speed of sound being a function of temperature, it is possible to establish the correlation between speed of sound and temperature, throughout a cross-section of the material, which correlation is programmed into a computer to provide for a continuous in-process measurement of temperature throughout the specimen.

  8. Problems of applications of high power IR radiation in aquatic medium under high pressure

    NASA Astrophysics Data System (ADS)

    Sorokin, Yurii V.; Kuzyakov, Boris A.

    2004-06-01

    In this work the effects that appear in the optical breakdown are analyzed in water and the time dependences received also for the velocities and pressures at the wave fronts. The application of acoustic waves, generated by high power laser pulses in the aqueous medium, has quite serious perspectives for sounding. It is shown in the work that under comparatively low power density of radiation, as a result of a surface layer heating, the thermoelastic sresses arise, leading to the excitation of the acoustic waves. The analysis showed that the prognostic evaluations of the values of a light deflagration area are possible for a clear aqueous medium with the pressures up to 400 kg/cm2. With the presence of microinhomogeneities, it is necessary to know their total physical and chemical properties and detailed trustworthy data by their spatial distribution. A principally new approach was developed to the problem of videoinformation transmission from the object surfaces by the fiber-optic channel. The application of a precision measuring TV-camera with a color format in the range 0.3 - 0.98 μm allows to raise the information capacity of the transmitted information. The optimization of vision module choice are considered also.

  9. Temperature Structure of the Intracluster Medium from Smoothed-particle Hydrodynamics and Adaptive-mesh Refinement Simulations

    NASA Astrophysics Data System (ADS)

    Rasia, Elena; Lau, Erwin T.; Borgani, Stefano; Nagai, Daisuke; Dolag, Klaus; Avestruz, Camille; Granato, Gian Luigi; Mazzotta, Pasquale; Murante, Giuseppe; Nelson, Kaylea; Ragone-Figueroa, Cinthia

    2014-08-01

    Analyses of cosmological hydrodynamic simulations of galaxy clusters suggest that X-ray masses can be underestimated by 10%-30%. The largest bias originates from both violation of hydrostatic equilibrium (HE) and an additional temperature bias caused by inhomogeneities in the X-ray-emitting intracluster medium (ICM). To elucidate this large dispersion among theoretical predictions, we evaluate the degree of temperature structures in cluster sets simulated either with smoothed-particle hydrodynamics (SPH) or adaptive-mesh refinement (AMR) codes. We find that the SPH simulations produce larger temperature variations connected to the persistence of both substructures and their stripped cold gas. This difference is more evident in nonradiative simulations, whereas it is reduced in the presence of radiative cooling. We also find that the temperature variation in radiative cluster simulations is generally in agreement with that observed in the central regions of clusters. Around R 500 the temperature inhomogeneities of the SPH simulations can generate twice the typical HE mass bias of the AMR sample. We emphasize that a detailed understanding of the physical processes responsible for the complex thermal structure in ICM requires improved resolution and high-sensitivity observations in order to extend the analysis to higher temperature systems and larger cluster-centric radii.

  10. Ramp temperature and Dufour effects on transient MHD natural convection flow past an infinite vertical plate in a porous medium

    NASA Astrophysics Data System (ADS)

    Marneni, Narahari; Tippa, Sowmya; Pendyala, Rajashekhar

    2015-12-01

    Analytical investigation of the unsteady natural convection flow along an infinite vertical plate embedded in a porous medium subjected to a ramped temperature boundary condition has been performed in the presence of magnetic field, thermal radiation, heat generation or absorption, chemical reaction and Dufour effect. The governing equations for momentum, energy and concentration have been solved using the Laplace transform technique. The closed-form exact solutions for the velocity, temperature and concentration fields as well as the skin-friction, Nusselt and Sherwood numbers are obtained without any restrictions. The influence of pertinent parameters on the fluid velocity, temperature, skin-friction and Nusselt number have been discussed in detailed through graphs. The natural convection due to ramped wall temperature (RWT) has also been compared with that of the constant wall temperature (CWT). It is observed that the fluid velocity and temperature profiles are greater in case of CWT than the case of RWT. Also it is noticed that the flow accelerates with increasing values of heat source parameter, permeability parameter and Dufour number while the flow retardation is observed with increasing values of radiation parameter, magnetic field parameter and Schmidt number.

  11. Peculiarities of the current-voltage characteristics of a Josephson medium in a YBCO high-temperature superconductor

    NASA Astrophysics Data System (ADS)

    Vasyutin, M. A.

    2013-12-01

    The influence of a weak magnetic field ( H < 150 Oe) on the current-voltage ( I- U) characteristic of a YBa2Cu3O7 - x (YBCO) high-temperature superconductor (HTSC) near the superconducting transition temperature has been studied. It is established that there exist narrow (<0.2 K) temperature regions where the I- U curve exhibits sharp bending for H < 30 Oe and the ohmic behavior changes to a quadratic dependence of the voltage on current in a region of several milliamperes. At higher temperatures, the I- U curve bending exhibits smearing. This behavior is observed at a temperature below that corresponding to a zero critical current. Above a certain current, the temperature and magnetic field exhibit equivalent effects on the I- U curve of YBCO. Experimental results are explained by a sharp decrease in the critical currents of intergranular Josephson junctions under the action of magnetic field and by the current-induced formation of uncoupled (with respect to the order parameter) superconducting grains. Characteristic currents for the transition of the intergranular Josephson medium into an incoherent state are determined and the first critical fields in YBCO are evaluated.

  12. Temperature structure of the intracluster medium from smoothed-particle hydrodynamics and adaptive-mesh refinement simulations

    SciTech Connect

    Rasia, Elena; Lau, Erwin T.; Nagai, Daisuke; Avestruz, Camille; Borgani, Stefano; Dolag, Klaus; Granato, Gian Luigi; Murante, Giuseppe; Ragone-Figueroa, Cinthia; Mazzotta, Pasquale; Nelson, Kaylea

    2014-08-20

    Analyses of cosmological hydrodynamic simulations of galaxy clusters suggest that X-ray masses can be underestimated by 10%-30%. The largest bias originates from both violation of hydrostatic equilibrium (HE) and an additional temperature bias caused by inhomogeneities in the X-ray-emitting intracluster medium (ICM). To elucidate this large dispersion among theoretical predictions, we evaluate the degree of temperature structures in cluster sets simulated either with smoothed-particle hydrodynamics (SPH) or adaptive-mesh refinement (AMR) codes. We find that the SPH simulations produce larger temperature variations connected to the persistence of both substructures and their stripped cold gas. This difference is more evident in nonradiative simulations, whereas it is reduced in the presence of radiative cooling. We also find that the temperature variation in radiative cluster simulations is generally in agreement with that observed in the central regions of clusters. Around R {sub 500} the temperature inhomogeneities of the SPH simulations can generate twice the typical HE mass bias of the AMR sample. We emphasize that a detailed understanding of the physical processes responsible for the complex thermal structure in ICM requires improved resolution and high-sensitivity observations in order to extend the analysis to higher temperature systems and larger cluster-centric radii.

  13. Temperature and hydration effects on absorbance spectra and radiation sensitivity of a radiochromic medium

    PubMed Central

    Rink, Alexandra; Lewis, David F.; Varma, Sangya; Vitkin, I. Alex; Jaffray, David A.

    2008-01-01

    The effects of temperature on real time changes in optical density (ΔOD) of GAFCHROMIC® EBT film were investigated. The spectral peak of maximum change in absorbance (λmax) was shown to downshift linearly when the temperature of the film was increased from 22 to 38 °C. The ΔOD values were also shown to decrease linearly with temperature, and this decrease could not be attributed to the shift in λmax. A compensation scheme using λmax and a temperature-dependent correction factor was investigated, but provided limited improvement. Part of the reason may be the fluctuations in hydration of the active component, which were found to affect both position of absorbance peaks and the sensitivity of the film. To test the effect of hydration, laminated and unlaminated films were desiccated. This shifted both the major and minor absorbance peaks in the opposite direction to the change observed with temperature. The desiccated film also exhibited reduced sensitivity to ionizing radiation. Rehydration of the desiccated films did not reverse the effects, but rather gave rise to another form of the polymer with absorbance maxima upshifted further 20 nm. Hence, the spectral characteristics and sensitivity of the film can be dependent on its history, potentially complicating both real-time and conventional radiation dosimetry. PMID:18975701

  14. Behavior of a hammerhead ribozyme in aqueous solution at medium to high temperatures.

    PubMed

    El-Murr, Nizar; Maurel, Marie-Christine; Rihova, Martina; Vergne, Jacques; Hervé, Guy; Kato, Mikio; Kawamura, Kunio

    2012-09-01

    The "RNA world" hypothesis proposes that--early in the evolution of life--RNA molecules played important roles both in information storage and in enzymatic functions. However, this hypothesis seems to be inconsistent with the concept that life may have emerged under hydrothermal conditions since RNA molecules are considered to be labile under such extreme conditions. Presently, the possibility that the last common ancestor of the present organisms was a hyperthermophilic organism which is important to support the hypothesis of the hydrothermal origin of life has been subject of strong discussions. Consequently, it is of importance to study the behavior of RNA molecules under hydrothermal conditions from the viewpoints of stability, catalytic functions, and storage of genetic information of RNA molecules and determination of the upper limit of temperature where life could have emerged. In the present work, self-cleavage of a natural hammerhead ribozyme was examined at temperatures 10-200 °C. Self-cleavage was investigated in the presence of Mg(2+), which facilitates and accelerates this reaction. Self-cleavage of the hammerhead ribozyme was clearly observed at temperatures up to 60 °C, but at higher temperatures self-cleavage occurs together with hydrolysis and with increasing temperature hydrolysis becomes dominant. The influence of the amount of Mg(2+) on the reaction rate was also investigated. In addition, we discovered that the reaction proceeds in the presence of high concentrations of monovalent cations (Na(+) or K(+)), although very slowly. Furthermore, at high temperatures (above 60 °C), monovalent cations protect the ribozyme against degradation. PMID:22915317

  15. Behavior of a hammerhead ribozyme in aqueous solution at medium to high temperatures

    NASA Astrophysics Data System (ADS)

    El-Murr, Nizar; Maurel, Marie-Christine; Rihova, Martina; Vergne, Jacques; Hervé, Guy; Kato, Mikio; Kawamura, Kunio

    2012-09-01

    The "RNA world" hypothesis proposes that—early in the evolution of life—RNA molecules played important roles both in information storage and in enzymatic functions. However, this hypothesis seems to be inconsistent with the concept that life may have emerged under hydrothermal conditions since RNA molecules are considered to be labile under such extreme conditions. Presently, the possibility that the last common ancestor of the present organisms was a hyperthermophilic organism which is important to support the hypothesis of the hydrothermal origin of life has been subject of strong discussions. Consequently, it is of importance to study the behavior of RNA molecules under hydrothermal conditions from the viewpoints of stability, catalytic functions, and storage of genetic information of RNA molecules and determination of the upper limit of temperature where life could have emerged. In the present work, self-cleavage of a natural hammerhead ribozyme was examined at temperatures 10-200 °C. Self-cleavage was investigated in the presence of Mg2+, which facilitates and accelerates this reaction. Self-cleavage of the hammerhead ribozyme was clearly observed at temperatures up to 60 °C, but at higher temperatures self-cleavage occurs together with hydrolysis and with increasing temperature hydrolysis becomes dominant. The influence of the amount of Mg2+ on the reaction rate was also investigated. In addition, we discovered that the reaction proceeds in the presence of high concentrations of monovalent cations (Na+ or K+), although very slowly. Furthermore, at high temperatures (above 60 °C), monovalent cations protect the ribozyme against degradation.

  16. Fuzzy Logic Controller for Low Temperature Application

    NASA Technical Reports Server (NTRS)

    Hahn, Inseob; Gonzalez, A.; Barmatz, M.

    1996-01-01

    The most common temperature controller used in low temperature experiments is the proportional-integral-derivative (PID) controller due to its simplicity and robustness. However, the performance of temperature regulation using the PID controller depends on initial parameter setup, which often requires operator's expert knowledge on the system. In this paper, we present a computer-assisted temperature controller based on the well known.

  17. 46 CFR 56.60-5 - Steel (High temperature applications).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Steel (High temperature applications). 56.60-5 Section... SYSTEMS AND APPURTENANCES Materials § 56.60-5 Steel (High temperature applications). (a) (Reproduces 124.2.A.) Upon prolonged exposure to temperatures above 775 °F (412 °C), the carbide phase of plain...

  18. 46 CFR 56.60-5 - Steel (High temperature applications).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Steel (High temperature applications). 56.60-5 Section... SYSTEMS AND APPURTENANCES Materials § 56.60-5 Steel (High temperature applications). (a) (Reproduces 124.2.A.) Upon prolonged exposure to temperatures above 775 °F (412 °C), the carbide phase of plain...

  19. 46 CFR 56.60-5 - Steel (High temperature applications).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Steel (High temperature applications). 56.60-5 Section... SYSTEMS AND APPURTENANCES Materials § 56.60-5 Steel (High temperature applications). (a) (Reproduces 124.2.A.) Upon prolonged exposure to temperatures above 775 °F (412 °C), the carbide phase of plain...

  20. 46 CFR 56.60-5 - Steel (High temperature applications).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Steel (High temperature applications). 56.60-5 Section... SYSTEMS AND APPURTENANCES Materials § 56.60-5 Steel (High temperature applications). (a) (Reproduces 124.2.A.) Upon prolonged exposure to temperatures above 775 °F (412 °C), the carbide phase of plain...

  1. Effects of initial temperature and tempering medium on thermal tempering of dental porcelains.

    PubMed

    Hojjatie, B; Anusavice, K J

    1993-03-01

    The objective of this study was to test the hypothesis that quenching of porcelain in silicone oil rather than in compressed air will significantly increase the flexure strength by reducing the potential for crack formation during transient cooling. A secondary hypothesis to be tested is that the initial tempering temperature can be reduced significantly below the porcelain maturing temperature of 982 degrees C but well above Tg without a decrease in strength. Opaque-body porcelain disks, 16 mm in diameter and 2 mm in thickness, with a thermal contraction mismatch (delta alpha) of -1.5, 0, and +3.2 ppm/degrees C were tempered from initial temperatures of 650, 750, 850, and 982 degrees C in silicone oil with kinematic viscosities of 50, 1000, and 5000 centistokes. Porcelain disks were also subjected to three cooling procedures in air: slow cooling in a furnace (SC), free convective cooling in a laboratory bench (FC), and tempering (T) by blasting the surface of body porcelain with air. The crack size induced by a Vickers microhardness indenter was measured within one minute after crack development. For determination of the influence of initial cooling temperature on biaxial flexure strength, six body porcelain disks (delta alpha = 0) were tempered in air from initial temperatures of 650, 750, 850, and 982 degrees C. The mean crack size of specimens tempered in oil was significantly smaller (p < or = 0.001) than that of specimens that were slowly-cooled or fast-cooled in air for all thermal contraction mismatch cases.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8450115

  2. Composite Materials for Low-Temperature Applications

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Composite materials with improved thermal conductivity and good mechanical strength properties should allow for the design and construction of more thermally efficient components (such as pipes and valves) for use in fluid-processing systems. These materials should have wide application in any number of systems, including ground support equipment (GSE), lunar systems, and flight hardware that need reduced heat transfer. Researchers from the Polymer Science and Technology Laboratory and the Cryogenics Laboratory at Kennedy Space Center were able to develop a new series of composite materials that can meet NASA's needs for lightweight materials/composites for use in fluid systems and also expand the plastic-additive markets. With respect to thermal conductivity and physical properties, these materials are excellent alternatives to prior composite materials and can be used in the aerospace, automotive, military, electronics, food-packaging, and textile markets. One specific application of the polymeric composition is for use in tanks, pipes, valves, structural supports, and components for hot or cold fluid-processing systems where heat flow through materials is a problem to be avoided. These materials can also substitute for metals in cryogenic and other low-temperature applications. These organic/inorganic polymeric composite materials were invented with significant reduction in heat transfer properties. Decreases of 20 to 50 percent in thermal conductivity versus that of the unmodified polymer matrix were measured. These novel composite materials also maintain mechanical properties of the unmodified polymer matrix. These composite materials consist of an inorganic additive combined with a thermoplastic polymer material. The intrinsic, low thermal conductivity of the additive is imparted into the thermoplastic, resulting in a significant reduction in heat transfer over that of the base polymer itself, yet maintaining most of the polymer's original properties. Normal

  3. Wave Propagation in a Rotating Transversely Isotropic Two-Temperature Generalized Thermoelastic Medium Without Dissipation

    NASA Astrophysics Data System (ADS)

    Singh, Baljeet

    2016-01-01

    The present paper is concerned with the propagation of plane waves in a rotating, transversely isotropic, two-temperature generalized thermoelastic solid half-space without energy dissipation. The governing equations are solved to show the existence of three plane waves in the x-z plane. The reflection of these plane waves from a thermally insulated free surface is also studied to obtain a system of three non-homogeneous equations in reflection coefficients of the reflected waves. The speeds and reflection coefficients are computed for a particular model of the half-space. The speeds and reflection coefficients of plane waves are shown graphically to observe the effects of anisotropy, two temperatures and rotation.

  4. Multifactorial modelling of high-temperature treatment of timber in the saturated water steam medium

    NASA Astrophysics Data System (ADS)

    Prosvirnikov, D. B.; Safin, R. G.; Ziatdinova, D. F.; Timerbaev, N. F.; Lashkov, V. A.

    2016-04-01

    The paper analyses experimental data obtained in studies of high-temperature treatment of softwood and hardwood in an environment of saturated water steam. Data were processed in the Curve Expert software for the purpose of statistical modelling of processes and phenomena occurring during this process. The multifactorial modelling resulted in the empirical dependences, allowing determining the main parameters of this type of hydrothermal treatment with high accuracy.

  5. Wave scattering by an irregularity slab embedded in a stratified medium - Applications to ionospheric propagation

    NASA Astrophysics Data System (ADS)

    Kiang, Y.-W.; Liu, C. H.

    1985-02-01

    Plane wave scattering by an irregularity slab embedded in a linearly stratified isotropic medium is studied under the single scatter approximation. In addition to regular reflection from the stratified background, both the incident and the reflected waves are scattered by the random irregularities. The behavior of the unperturbed field in the neighborhood of the turning point is accurately taken into account by using the full wave solution. The scattered fields can be interpreted in terms of the Bragg condition similar to the case of the well-known Booker-Gordon form, but with four terms accounting for the reflection effect of the turning point on both the unperturbed and scattered waves. The case of elongated irregularities is studied in detail. Analytical expression for the angular spectrum of the average scattered field intensity is derived, and its physical meaning discussed. In comparison with the case where the background medium is homogeneous, the relation to the two-dimensional Booker-Gordon formula is clarified. Applications to high-frequency propagation in the disturbed ionosphere are discussed.

  6. A comparison of low voltage IGBTs vs. medium voltage IGCTs for hydraulic turbine generator applications

    SciTech Connect

    LeGoy, P.R.

    1999-11-01

    Variable speed hydraulic turbine power generation has become a useful tool in the chemical processing industry. The technology that preceded and led to the use of variable speed hydraulic turbines was Variable Speed Constant Frequency (VSCF) drives for power generation. The current state of the art in the VSCF technology is the Insulated Gate Bipolar Transistor (IGBT), voltage source, Pulse Width Modulation (PWM) drive. A new PWM switch has been created. The new switch is the Integrated Gate-Commutated Thyristor (IGCT), PWM device. The drives produced with this technology are current source therefore the operational voltages of the drives are easily configured for medium voltage range. Medium voltage power makes the new drives desirable because of the size of the generators. A common power range for variable speed Hydraulic Power Generation is 1MW and applications for the chemical processing industry have a trend toward higher powers. For this type generator: if the operational voltage falls below 2300V the size of the generator becomes too large, bulky and expensive. Windings are no longer wires; they become bussbars. The current solution to the voltage problem is to include a transformer in the generator/drive connection.

  7. Market Assessment of Biomass Gasification and Combustion Technology for Small- and Medium-Scale Applications

    SciTech Connect

    Peterson, D.; Haase, S.

    2009-07-01

    This report provides a market assessment of gasification and direct combustion technologies that use wood and agricultural resources to generate heat, power, or combined heat and power (CHP) for small- to medium-scale applications. It contains a brief overview of wood and agricultural resources in the U.S.; a description and discussion of gasification and combustion conversion technologies that utilize solid biomass to generate heat, power, and CHP; an assessment of the commercial status of gasification and combustion technologies; a summary of gasification and combustion system economics; a discussion of the market potential for small- to medium-scale gasification and combustion systems; and an inventory of direct combustion system suppliers and gasification technology companies. The report indicates that while direct combustion and close-coupled gasification boiler systems used to generate heat, power, or CHP are commercially available from a number of manufacturers, two-stage gasification systems are largely in development, with a number of technologies currently in demonstration. The report also cites the need for a searchable, comprehensive database of operating combustion and gasification systems that generate heat, power, or CHP built in the U.S., as well as a national assessment of the market potential for the systems.

  8. Inverse electromagnetic scattering in a two-layered medium with an application to mine detection

    NASA Astrophysics Data System (ADS)

    Delbary, Fabrice; Erhard, Klaus; Kress, Rainer; Potthast, Roland; Schulz, Jochen

    2008-02-01

    The detection of metallic objects is an important application in state-of-the-art security technology. In particular, for humanitarian mine detection the task is to detect objects that are buried in soil. Usually hand-held mine detectors create an electromagnetic pulse via a current in some wire loop and evaluate the scattered electromagnetic field via induction in a receiver loop that is moved together with the sender loop. This receiver signal can then be employed in identifying the location and the shape of metallic objects. Here, we model the full electromagnetic scattering problem in a two-layered medium from a perfectly conducting obstacle using boundary integral equations. The scattered field is modeled via a boundary layer approach and for its kernel the Green's matrix for the two-layered medium is constructed. We establish uniqueness and existence for the solution of the corresponding boundary integral equation. In the second part of the paper, we employ a direct search method for parameter estimation to find the location and size of some simple metallic objects from measurements of the induced voltage for a number of sender-receiver-loop positions.

  9. Efficiency of a novel forensic room-temperature DNA storage medium.

    PubMed

    Frippiat, Christophe; Noel, Fabrice

    2014-03-01

    The success of forensic genetics has led to considerable numbers of DNA samples that must be stored. Thus, the ability to preserve the integrity of forensic samples is essential. The possibility of retesting these samples after many years should be guaranteed. DNA storage typically requires the use of freezers. Recently, a new method that enables DNA to be stored at room temperature was developed. This technology is based on the principles of anhydrobiosis and thus permits room-temperature storage of DNA. This study evaluates the ability of this technology to preserve DNA samples mimicking true mixture casework samples for long periods of time. Mixed human DNA from 2 or 3 persons and at low concentrations was dried and stored for a period ranging from 6 months to 2 years in the presence of a desiccant. The quality of the stored DNA was evaluated based on quantitative peak height results from Short Tandem Repeat (STR) genotyping and the number of observed alleles. Furthermore, we determined whether this matrix has a potential inhibitory or enhancing effect on the PCR genotyping reactions. In our previous work, we demonstrated the considerable potential of this new technology. The present study complements our previous work. Our results show that after 2 years of aging at room temperature, there is a decrease in the number of observed alleles and in the peak height of these alleles. PMID:24528585

  10. A Cloud-Assisted Random Linear Network Coding Medium Access Control Protocol for Healthcare Applications

    PubMed Central

    Kartsakli, Elli; Antonopoulos, Angelos; Alonso, Luis; Verikoukis, Christos

    2014-01-01

    Relay sensor networks are often employed in end-to-end healthcare applications to facilitate the information flow between patient worn sensors and the medical data center. Medium access control (MAC) protocols, based on random linear network coding (RLNC), are a novel and suitable approach to efficiently handle data dissemination. However, several challenges arise, such as additional delays introduced by the intermediate relay nodes and decoding failures, due to channel errors. In this paper, we tackle these issues by adopting a cloud architecture where the set of relays is connected to a coordinating entity, called cloud manager. We propose a cloud-assisted RLNC-based MAC protocol (CLNC-MAC) and develop a mathematical model for the calculation of the key performance metrics, namely the system throughput, the mean completion time for data delivery and the energy efficiency. We show the importance of central coordination in fully exploiting the gain of RLNC under error-prone channels. PMID:24618727

  11. Effect of Storage Temperature on Cultured Epidermal Cell Sheets Stored in Xenobiotic-Free Medium

    PubMed Central

    Jackson, Catherine; Aabel, Peder; Eidet, Jon R.; Messelt, Edward B.; Lyberg, Torstein; von Unge, Magnus; Utheim, Tor P.

    2014-01-01

    Cultured epidermal cell sheets (CECS) are used in regenerative medicine in patients with burns, and have potential to treat limbal stem cell deficiency (LSCD), as demonstrated in animal models. Despite widespread use, short-term storage options for CECS are limited. Advantages of storage include: flexibility in scheduling surgery, reserve sheets for repeat operations, more opportunity for quality control, and improved transportation to allow wider distribution. Studies on storage of CECS have thus far focused on cryopreservation, whereas refrigeration is a convenient method commonly used for whole skin graft storage in burns clinics. It has been shown that preservation of viable cells using these methods is variable. This study evaluated the effect of different temperatures spanning 4°C to 37°C, on the cell viability, morphology, proliferation and metabolic status of CECS stored over a two week period in a xenobiotic–free system. Compared to non-stored control, best cell viability was obtained at 24°C (95.2±9.9%); reduced cell viability, at approximately 60%, was demonstrated at several of the temperatures (12°C, 28°C, 32°C and 37°C). Metabolic activity was significantly higher between 24°C and 37°C, where glucose, lactate, lactate/glucose ratios, and oxygen tension indicated increased activation of the glycolytic pathway under aerobic conditions. Preservation of morphology as shown by phase contrast and scanning electron micrographs was best at 12°C and 16°C. PCNA immunocytochemistry indicated that only 12°C and 20°C allowed maintenance of proliferative function at a similar level to non-stored control. In conclusion, results indicate that 12°C and 24°C merit further investigation as the prospective optimum temperature for short-term storage of cultured epidermal cell sheets. PMID:25170754

  12. LCOE reduction for parabolic trough CSP: Innovative solar receiver with improved performance at medium temperature

    NASA Astrophysics Data System (ADS)

    Stollo, A.; Chiarappa, T.; D'Angelo, A.; Maccari, A.; Matino, F.

    2016-05-01

    Concentrated Solar Power (CSP) applications represent an effective possibility to gain energy from the Sun; however, the lasting CSP market crisis compels continuous improvements in terms of cost reduction and performance increase. Focused on parabolic trough technology, this paper describes the innovation studied and realized on solar receivers to gain optimized optical performance while increasing the production versatility, hence boosting the solar plant efficiency and finally reducing the estimated LCOE.

  13. NASA space applications of high-temperature superconductors

    NASA Technical Reports Server (NTRS)

    Heinen, Vernon O.; Sokoloski, Martin M.; Aron, Paul R.; Bhasin, Kul B.

    1992-01-01

    The application of superconducting technology in space has been limited by the requirement of cooling to near liquid helium temperatures. The only means of attaining these temperatures has been with cryogenic fluids which severely limits mission lifetime. The development of materials with superconducting transition temperatures (T sub c) above 77 K has made superconducting technology more attractive and feasible for employment in aerospace systems. Potential applications of high-temperature superconducting technology in cryocoolers and remote sensing, communications, and power systems are discussed.

  14. NASA Space applications of high-temperature superconductors

    NASA Technical Reports Server (NTRS)

    Heinen, Vernon O.; Sokoloski, Martin M.; Aron, Paul R.; Bhasin, Kul B.; Wintucky, Edwin G.; Connolly, Denis J.

    1992-01-01

    The application of superconducting technology in space has been limited by the requirement of cooling to near liquid helium temperatures. The only means of obtaining these temperatures has been with cryogenic fluids which severely limit mission lifetime. The development of materials with superconducting transition temperatures above 77 K has made superconducting technology more attractive and feasible for employment in aerospace systems. Here, potential applications of high temperature superconducting technology in cryocoolers, remote sensing, communications, and power systems are discussed.

  15. Nuclear fuels for very high temperature applications

    SciTech Connect

    Lundberg, L.B.; Hobbins, R.R.

    1992-08-01

    The success of the development of nuclear thermal propulsion devices and thermionic space nuclear power generation systems depends on the successful utilization of nuclear fuel materials at temperatures in the range 2000 to 3500 K. Problems associated with the utilization of uranium bearing fuel materials at these very high temperatures while maintaining them in the solid state for the required operating times are addressed. The critical issues addressed include evaporation, melting, reactor neutron spectrum, high temperature chemical stability, fabrication, fission induced swelling, fission product release, high temperature creep, thermal shock resistance, and fuel density, both mass and fissile atom. Candidate fuel materials for this temperature range are based on UO{sub 2} or uranium carbides. Evaporation suppression, such as a sealed cladding, is required for either fuel base. Nuclear performance data needed for design are sparse for all candidate fuel forms in this temperature range, especially at the higher temperatures.

  16. Nuclear fuels for very high temperature applications

    SciTech Connect

    Lundberg, L.B.; Hobbins, R.R.

    1992-01-01

    The success of the development of nuclear thermal propulsion devices and thermionic space nuclear power generation systems depends on the successful utilization of nuclear fuel materials at temperatures in the range 2000 to 3500 K. Problems associated with the utilization of uranium bearing fuel materials at these very high temperatures while maintaining them in the solid state for the required operating times are addressed. The critical issues addressed include evaporation, melting, reactor neutron spectrum, high temperature chemical stability, fabrication, fission induced swelling, fission product release, high temperature creep, thermal shock resistance, and fuel density, both mass and fissile atom. Candidate fuel materials for this temperature range are based on UO{sub 2} or uranium carbides. Evaporation suppression, such as a sealed cladding, is required for either fuel base. Nuclear performance data needed for design are sparse for all candidate fuel forms in this temperature range, especially at the higher temperatures.

  17. Fractography of the high temperature hydrogen attack of a medium carbon steel

    NASA Technical Reports Server (NTRS)

    Nelson, H. G.; Moorhead, R. D.

    1976-01-01

    Results are reported for an experimental study of the microscopic fracture processes associated with hydrogen attack of a commercially produced plain carbon steel in a well-controlled high-temperature hydrogen environment of high purity. In the experiments, sheet samples were exposed to laboratory-grade hydrogen at a pressure of 3.5 MN/sq m and a temperature of 575 C. The fractography of gas-filled fissures and failed tension specimens is analyzed in an effort to identify any predominant microstructural defect associated with fissure formation, the prevalent modes of fracture, and the contribution of gas-filled fissures to the overall failure process. It is found that the tensile properties of the examined steel were significantly degraded after as few as 136 hr of exposure to a high-purity hydrogen atmosphere at 575 C; that the yield strength, ultimate strength, and elongation at fracture were all reduced progressively with increasing exposure time; and that the yield and ultimate strengths were reduced more than 40% after 408 hr while elongation was reduced to less than 2%.

  18. Analysis of mixed micellar behavior of cationic gemini alkanediyl-α,ω-bis(dimethylcetylammonium bromide) series with ionic and nonionic hydrotropes in aqueous medium at different temperatures.

    PubMed

    Khan, Iqrar Ahmad; Khanam, Ahmad Jahan; Sheikh, Mohmad Shafi; Kabir-ud-Din

    2011-12-29

    The interaction between cationic symmetrical gemini alkanediyl-α,ω-bis(dimethylcetylammonium bromide) series (16-s-16, s = 5, 6, abbreviated as G5 and G6) with hydrotropes (cationic: aniline hydrochloride, para-toluidine hydrochloride, and ortho-toluidine hydrochloride; nonionic: phenol, resorcinol, and pyrogallol) in aqueous medium has been investigated at four different temperatures ranging from 298.15 to 313.15 K. Different physicochemical parameters such as critical micelle concentration (cmc), interaction parameter (β(m), an energetic parameter that represents the excess Gibbs free energy of mixing), activity coefficients (f(i)), mole fraction of hydrotrope in mixed micelles at ideal mixing conditions (X(1)(ideal))(,) excess free energy of mixing (Δ(mix)G(E)), standard enthalpy (Δ(mic)H°), entropy (Δ(mic)S°), and Gibbs free energy (Δ(mic)G°) of micellization were evaluated and then intracompared. For further understanding, similar studies were carried out with their conventional counterpart cetyltrimethyl ammonium bromide (CTAB) and then compared. The bulk behaviors were explored using different theoretical models of Clint, Rubingh, and Motomura for justification and comparison of results of different binary combinations of hydrotropes with the gemini series and CTAB. Synergistic interaction was observed in all binary combinations at all temperatures in the micelles which decreases slightly with increasing temperature. This study will give insight into the selection of surfactants in different applications as their properties get modified by interaction with hydrotropes, thus influencing their solution behavior which, in turn, modifying the phase-forming behavior, microemulsion, liquid crystal forming systems, clouding phenomenon, cleaning, and laundry processes besides solubilization. The ability of hydrotropes to dramatically alter the solubility of other molecules in a medium can be exploited for the purpose of selective encapsulation and release

  19. Proton Content and Nature in Perovskite Ceramic Membranes for Medium Temperature Fuel Cells and Electrolysers

    PubMed Central

    Colomban, Philippe; Zaafrani, Oumaya; Slodczyk, Aneta

    2012-01-01

    Recent interest in environmentally friendly technology has promoted research on green house gas-free devices such as water steam electrolyzers, fuel cells and CO2/syngas converters. In such applications, proton conducting perovskite ceramics appear especially promising as electrolyte membranes. Prior to a successful industrial application, it is necessary to determine/understand their complex physical and chemical behavior, especially that related to proton incorporation mechanism, content and nature of bulk protonic species. Based on the results of quasi-elastic neutron scattering (QNS), thermogravimetric analysis (TGA), Raman and IR measurements we will show the complexity of the protonation process and the importance of differentiation between the protonic species adsorbed on a membrane surface and the bulk protons. The bulk proton content is very low, with a doping limit (~1–5 × 10−3 mole/mole), but sufficient to guarantee proton conduction below 600 °C. The bulk protons posses an ionic, covalent bond free nature and may occupy an interstitial site in the host perovskite structure. PMID:24958293

  20. Method of dispensing droplets to penetration-resistive mediums. [Patent application

    DOEpatents

    Fowler, V.L.; Ryon, A.D.; Haas, P.A.

    1982-06-10

    Uniform, monosized microspheroids are produced in a gelation medium characterized by a high resistance to surface penetration by reducing the effect of impact on entry of the droplets into the medium by contacting the droplet with a stream of medium and by introducing the resulting stream into a gelation column.

  1. Evaluation of microstructure anisotropy on room and medium temperature ECAP deformed F138 steel

    SciTech Connect

    De Vincentis, N.S.; Kliauga, A.; Ferrante, M.; Avalos, M.; Brokmeier, H.-G.; Bolmaro, R.E.

    2015-09-15

    The microstructure developed during severe plastic deformation results in improved mechanical properties because of the decrease in domain sizes and accumulation of defects, mainly dislocation arrays. The characteristic deformation stages observed in low stacking fault energy (SFE) face centered cubic (FCC) materials are highly influenced by the development of the primary and secondary twinning that compete with dislocation glide. In this paper, a low SFE F138 stainless steel is deformed by equal channel angular pressing (ECAP) up to 4 passes at room temperature (RT) and at 300 °C to compare the grain refinement and twin boundary development with increasing deformation. Tensile tests were performed to determine the deformation stages reached by the material before and after ECAP deformation, and the resulting microstructure was observed by TEM. X-ray diffraction and EBSD, average technique the first and local the second one, were used to quantify the microstructural changes, allowing the determination of diffraction domain sizes, dislocation and stacking fault densities and misorientation indices, which lead to a complete analysis of the deformation introduced in the material, with comparative correlations between various microstructural parameters. - Highlights: • The microstructure of ECAP pressed F138 steel was studied using TEM, EBSD and XRD. • Increasing deformation reduced domain sizes and increased dislocation densities. • Dislocation array compactness and misorientation increased with higher deformation. • Largest dislocation densities, mostly screw, match with simultaneous activation of twins. • Several correlations among microstructural features and parameters have been disclosed.

  2. The impact of background radiation, illumination and temperature on EMF-induced changes of aqua medium properties.

    PubMed

    Naira, Baghdasaryan; Yerazik, Mikayelyan; Anna, Nikoghosyan; Sinerik, Ayrapetyan

    2013-09-01

    The effects of extremely low frequency electromagnetic field (ELF EMF) on physicochemical properties of physiological solution at different environmental media were studied. The existence of frequency "windows" at 4 and 8 Hz frequencies of ELF EMF having effects on heat fusion period, hydrogen peroxide (H2O2) formation and oxygen (O2) content of water solution and different dependency on temperature, background radiation and illumination was shown. Obtained data allow us to suggest that EMF-induced effect on water physicochemical properties depends on abovementioned environmental factors. As cell bathing medium is a target for biological effects of ELF EMF, the variability of experimental data on biological effects of EMF, obtained in different laboratories, can be explained by different environmental conditions of experiments, which very often are not considered adequately. PMID:23323624

  3. Constraining the temperature-density relation of the intergalactic medium with the Lyman α and β forests

    NASA Astrophysics Data System (ADS)

    Boera, Elisa; Murphy, Michael T.; Becker, George D.; Bolton, James S.

    2016-02-01

    The post-reionization thermal state of the intergalactic medium is characterized by a power-law relationship between temperature and density, with a slope determined by the parameter γ. We describe a new method to measure γ using the ratio of flux curvature in the Lyman α and β forests. At a given redshift, this curvature ratio incorporates information from the different gas densities traced by Lyman α and β absorption. It is relatively simple and fast to compute and appears robust against several observational uncertainties. We apply this technique to a sample of 27 high-resolution quasar spectra from the Very Large Telescope. While promising statistical errors on γ appear to be achievable with these spectra, to reach its full potential, the dependence of the curvature ratio on the thermal state of the gas in the foreground Lyman α forest will require further, detailed forward modelling.

  4. Nonlinear Constitutive Relations for High Temperature Application, 1984

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Nonlinear constitutive relations for high temperature applications were discussed. The state of the art in nonlinear constitutive modeling of high temperature materials was reviewed and the need for future research and development efforts in this area was identified. Considerable research efforts are urgently needed in the development of nonlinear constitutive relations for high temperature applications prompted by recent advances in high temperature materials technology and new demands on material and component performance. Topics discussed include: constitutive modeling, numerical methods, material testing, and structural applications.

  5. Design for ASIC reliability for low-temperature applications

    NASA Technical Reports Server (NTRS)

    Chen, Yuan; Mojaradi, Mohammad; Westergard, Lynett; Billman, Curtis; Cozy, Scott; Burke, Gary; Kolawa, Elizabeth

    2005-01-01

    In this paper, we present a methodology to design for reliability for low temperature applications without requiring process improvement. The developed hot carrier aging lifetime projection model takes into account both the transistor substrate current profile and temperature profile to determine the minimum transistor size needed in order to meet reliability requirements. The methodology is applicable for automotive, military, and space applications, where there can be varying temperature ranges. A case study utilizing this methodology is given to design for reliability into a custom application-specific integrated circuit (ASIC) for a Mars exploration mission.

  6. Electrical transport anisotropy of uniaxial polycrystalline samples and the effective medium approximation: An application to HTS

    NASA Astrophysics Data System (ADS)

    Cruz-García, A.; Muné, P.

    2016-08-01

    In this paper we have applied the effective medium approximation (EMA) to a polycrystalline sample made up of uniaxial crystallites with similar behavior to the high critical temperature superconductors (HTS) at the normal state (σab ≫ σc). As a result the dependence of the anisotropy parameter at the level of the sample, μ =σx /σz , on orientation probability of the grains' a-axes along a certain preferential direction, γxa is obtained. The intrinsic and shape anisotropy parameters of the crystallites constitute input data. In addition, the dependence of the orientation factor, f, which has been introduced in current models on the transport properties of HTS, is calculated as a function of γxa. These results offer a tool to interpret electrical transport measurements at normal state in granular uniaxial superconducting materials with certain texture degree, by means of the correlation between microstructure and electrical transport properties. Moreover, the comparison between the model and some experimental data suggests the presence of intragranular planar defects in the polycrystalline superconductors. They may affect the measurement of paracoherent resistivity and consequently the determination of f mainly in Bi based samples.

  7. Exceptional damage-tolerance of a medium-entropy alloy CrCoNi at cryogenic temperatures.

    PubMed

    Gludovatz, Bernd; Hohenwarter, Anton; Thurston, Keli V S; Bei, Hongbin; Wu, Zhenggang; George, Easo P; Ritchie, Robert O

    2016-01-01

    High-entropy alloys are an intriguing new class of metallic materials that derive their properties from being multi-element systems that can crystallize as a single phase, despite containing high concentrations of five or more elements with different crystal structures. Here we examine an equiatomic medium-entropy alloy containing only three elements, CrCoNi, as a single-phase face-centred cubic solid solution, which displays strength-toughness properties that exceed those of all high-entropy alloys and most multi-phase alloys. At room temperature, the alloy shows tensile strengths of almost 1 GPa, failure strains of ∼70% and KJIc fracture-toughness values above 200 MPa  m(1/2); at cryogenic temperatures strength, ductility and toughness of the CrCoNi alloy improve to strength levels above 1.3 GPa, failure strains up to 90% and KJIc values of 275 MPa  m(1/2). Such properties appear to result from continuous steady strain hardening, which acts to suppress plastic instability, resulting from pronounced dislocation activity and deformation-induced nano-twinning. PMID:26830651

  8. Exceptional damage-tolerance of a medium-entropy alloy CrCoNi at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Gludovatz, Bernd; Hohenwarter, Anton; Thurston, Keli V. S.; Bei, Hongbin; Wu, Zhenggang; George, Easo P.; Ritchie, Robert O.

    2016-02-01

    High-entropy alloys are an intriguing new class of metallic materials that derive their properties from being multi-element systems that can crystallize as a single phase, despite containing high concentrations of five or more elements with different crystal structures. Here we examine an equiatomic medium-entropy alloy containing only three elements, CrCoNi, as a single-phase face-centred cubic solid solution, which displays strength-toughness properties that exceed those of all high-entropy alloys and most multi-phase alloys. At room temperature, the alloy shows tensile strengths of almost 1 GPa, failure strains of ~70% and KJIc fracture-toughness values above 200 MPa m1/2 at cryogenic temperatures strength, ductility and toughness of the CrCoNi alloy improve to strength levels above 1.3 GPa, failure strains up to 90% and KJIc values of 275 MPa m1/2. Such properties appear to result from continuous steady strain hardening, which acts to suppress plastic instability, resulting from pronounced dislocation activity and deformation-induced nano-twinning.

  9. Exceptional damage-tolerance of a medium-entropy alloy CrCoNi at cryogenic temperatures

    PubMed Central

    Gludovatz, Bernd; Hohenwarter, Anton; Thurston, Keli V. S.; Bei, Hongbin; Wu, Zhenggang; George, Easo P.; Ritchie, Robert O.

    2016-01-01

    High-entropy alloys are an intriguing new class of metallic materials that derive their properties from being multi-element systems that can crystallize as a single phase, despite containing high concentrations of five or more elements with different crystal structures. Here we examine an equiatomic medium-entropy alloy containing only three elements, CrCoNi, as a single-phase face-centred cubic solid solution, which displays strength-toughness properties that exceed those of all high-entropy alloys and most multi-phase alloys. At room temperature, the alloy shows tensile strengths of almost 1 GPa, failure strains of ∼70% and KJIc fracture-toughness values above 200 MPa  m1/2; at cryogenic temperatures strength, ductility and toughness of the CrCoNi alloy improve to strength levels above 1.3 GPa, failure strains up to 90% and KJIc values of 275 MPa  m1/2. Such properties appear to result from continuous steady strain hardening, which acts to suppress plastic instability, resulting from pronounced dislocation activity and deformation-induced nano-twinning. PMID:26830651

  10. Bimetallic nanostructures. II. Finite temperature and applications

    NASA Astrophysics Data System (ADS)

    Montejano-Carrizales, J. M.; Morán-López, J. L.

    1990-12-01

    A systematic study of ordering and segregation at finite temperatures in bimetallic nanoclusters is presented. Icosahedral and cubo-octahedral clusters, with a total number of atoms, N = 13, 55 and 147, are studied. The equilibrium configuration is obtained by calculating the free energy within the regular solution model. The theory is applied to CuPd, NiPt and CuNi nanoclusters. We present results for the temperature dependence of the concentrations at the different shells around the central atom. In most of the cases a strong segregation is found.

  11. Towards smart energy systems: application of kernel machine regression for medium term electricity load forecasting.

    PubMed

    Alamaniotis, Miltiadis; Bargiotas, Dimitrios; Tsoukalas, Lefteri H

    2016-01-01

    Integration of energy systems with information technologies has facilitated the realization of smart energy systems that utilize information to optimize system operation. To that end, crucial in optimizing energy system operation is the accurate, ahead-of-time forecasting of load demand. In particular, load forecasting allows planning of system expansion, and decision making for enhancing system safety and reliability. In this paper, the application of two types of kernel machines for medium term load forecasting (MTLF) is presented and their performance is recorded based on a set of historical electricity load demand data. The two kernel machine models and more specifically Gaussian process regression (GPR) and relevance vector regression (RVR) are utilized for making predictions over future load demand. Both models, i.e., GPR and RVR, are equipped with a Gaussian kernel and are tested on daily predictions for a 30-day-ahead horizon taken from the New England Area. Furthermore, their performance is compared to the ARMA(2,2) model with respect to mean average percentage error and squared correlation coefficient. Results demonstrate the superiority of RVR over the other forecasting models in performing MTLF. PMID:26835237

  12. Supporting data intensive applications with medium grained parallelism. Final report, July 1991--June 1994

    SciTech Connect

    Pfaltz, J.L.; French, J.C.; Grimshaw, A.S.; Son, S.H.

    1994-07-01

    The purpose of this second three year grant was to investigate opportunities for medium grained parallelism in data intensive applications; or more succinctly, can one create effective parallel database systems? It should be noted that the last three years have not been kind to parallel object-oriented database systems -- to their knowledge none of those that have been implemented has been particularly effective. Nevertheless, this research has been some of the most successful that the principal investigators have conducted. One reason is that the authors took a multi-way approach. In consequence, they seem to have made far more progress than comparable research groups. A second, implicit goal was to complete the innovative functional, object-oriented database language and system, called ADAMS, and to demonstrate its performance in a parallel environment. Thus the overall agenda was (a) to create new mechanisms that exploit parallel computing power, (b) install it in ADAMS, and (c) analyze its behavior. It will be seen, that while they did come up with several new innovative ideas which they thoroughly tested, they did not always have time to install them into the run-time ADAMS library. Although the authors proposed rewriting their storage manager to take advantage of the Concurrent File System (CFS) on the Intel iPSC/2, they did not. During the grant period, the Computer Science Department acquired a dedicated cluster of 8 SPARC 10`s. Gradually the hypercube implementation has been phased out, and replaced by that on the SPARC cluster.

  13. Calculating the performance of 1{endash}3 piezoelectric composites for hydrophone applications: An effective medium approach

    SciTech Connect

    Avellaneda, M.; Swart, P.J.

    1998-03-01

    A new method is presented for evaluating the performance of 1{endash}3 polymer/piezoelectric ceramic composites for hydrophone applications. The Poisson`s ratio effect, i.e., the enhancement of the hydrostatic performance which can be achieved by mixing piezoelectric ceramics with polymers, is studied in detail. Using an `effective medium` approach, algebraic expressions are derived for the composite hydrostatic charge coefficient d{sub h}, the hydrostatic figure of merit d{sub h}g{sub h}, and the hydrostatic electromechanical coupling coefficient k{sub h} in terms of the properties of the constituent materials, the ceramic volume fraction, and a microstructural parameter p. The high contrast in stiffness and dielectric constants existing between the two phases can be exploited to derive simple, geometry-independent approximations which explain quantitatively the Poisson`s ratio effect. It is demonstrated that the stiffness and the Poisson`s ratio of the polymer matrix play a crucial role in enhancing hydrophone performance. Using a differential scheme to model the parameter p, we evaluate d{sub h}, d{sub h}g{sub h}, and k{sub h} for polymer/piezoelectric ceramic systems at varying compositions. Several examples involving Pb(Zr,Ti)O{sub 3} and (Pb,Ca)TiO{sub 3} piezoelectric ceramics are given to illustrate the theory. {copyright} {ital 1998 Acoustical Society of America.}

  14. Are fragment-based quantum chemistry methods applicable to medium-sized water clusters?

    PubMed

    Yuan, Dandan; Shen, Xiaoling; Li, Wei; Li, Shuhua

    2016-06-28

    Fragment-based quantum chemistry methods are either based on the many-body expansion or the inclusion-exclusion principle. To compare the applicability of these two categories of methods, we have systematically evaluated the performance of the generalized energy based fragmentation (GEBF) method (J. Phys. Chem. A, 2007, 111, 2193) and the electrostatically embedded many-body (EE-MB) method (J. Chem. Theory Comput., 2007, 3, 46) for medium-sized water clusters (H2O)n (n = 10, 20, 30). Our calculations demonstrate that the GEBF method provides uniformly accurate ground-state energies for 10 low-energy isomers of three water clusters under study at a series of theory levels, while the EE-MB method (with one water molecule as a fragment and without using the cutoff distance) shows a poor convergence for (H2O)20 and (H2O)30 when the basis set contains diffuse functions. Our analysis shows that the neglect of the basis set superposition error for each subsystem has little effect on the accuracy of the GEBF method, but leads to much less accurate results for the EE-MB method. The accuracy of the EE-MB method can be dramatically improved by using an appropriate cutoff distance and using two water molecules as a fragment. For (H2O)30, the average deviation of the EE-MB method truncated up to the three-body level calculated using this strategy (relative to the conventional energies) is about 0.003 hartree at the M06-2X/6-311++G** level, while the deviation of the GEBF method with a similar computational cost is less than 0.001 hartree. The GEBF method is demonstrated to be applicable for electronic structure calculations of water clusters at any basis set. PMID:27263629

  15. Improved Seals for High Temperature Airframe Applications

    NASA Technical Reports Server (NTRS)

    DeMange, Jeffrey J.; Dunlap, Patrick H.; Steinetz, Bruce M.

    2006-01-01

    Current thermal barrier seals, such as those used on the Space Shuttle, are insufficient to fully meet the demands of future hypersonic vehicles and reentry spacecraft. Previous investigations have demonstrated limited usage temperatures, as evidenced by a decreased ability to maintain sealing effectiveness at high temperatures (i.e., inadequate resiliency). In order to improve resiliency at elevated temperatures, Rene 41 (Allvac) was substituted for Inconel X-750 (Special Metals Corp.) as the spring tube material in the existing seal design. A seal construction incorporating the Rene 41 spring tube was fabricated and tested against the baseline Inconel X-750 spring tube seal. Although resiliency improvements were not as dramatic as in previous tests with the spring tubes alone, seals incorporating the Rene 41 spring tube exhibited an average 20 percent resiliency enhancement up to 1750 F when compared to seals containing the Inconel spring tube. In addition, the seals with the Rene 41 spring tubes showed less reduction in resiliency as temperatures increased above 1200 F. Results also indicated the Saffil (Saffil Ltd.) insulation in the core of the seal contributed more to resiliency than previously thought. Leakage data did not demonstrate an improvement with the seal containing the Rene 41 spring tube. However, based upon resiliency results, one could reasonably expect the Rene 41 version of the seal to track gap openings over a wider range. Therefore it would exhibit lower leakage than the Inconel X-750 version as the seal gap opens during a typical mission.

  16. High Temperature Materials for Chemical Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Elam, Sandra; Hickman, Robert; O'Dell, Scott

    2007-01-01

    Radiation or passively cooled thrust chambers are used for a variety of chemical propulsion functions including apogee insertion, reaction control for launch vehicles, and primary propulsion for planetary spacecraft. The performance of these thrust chambers is limited by the operating temperature of available materials. Improved oxidation resistance and increased operating temperatures can be achieved with the use of thermal barrier coatings such as zirconium oxide (ZrO2) and hafnium oxide (HfO2). However, previous attempts to include these materials showed cracking and spalling of the oxide layer due to poor bonding. Current research at NASA's Marshall Space Flight Center (MSFC) has generated unique, high temperature material options for in-space thruster designs that are capable of up to 2500 C operating temperatures. The research is focused on fabrication technologies to form low cost Iridium,qF_.henium (Ir/Re) components with a ceramic hot wall created as an integral, functionally graded material (FGM). The goal of this effort is to further de?celop proven technologies for embedding a protective ceramic coating within the Ir/Re liner to form a robust functional gradient material. Current work includes the fabrication and testing of subscale samples to evaluate tensile, creep, thermal cyclic/oxidation, and thermophysical material properties. Larger test articles have also being fabricated and hot-fire tested to demonstrate the materials in prototype thrusters at 1O0 lbf thrust levels.

  17. High temperature electronics applications in space exploration

    NASA Technical Reports Server (NTRS)

    Jurgens, R. F.

    1981-01-01

    The extension of the range of operating temperatures of electronic components and systems for planetary exploration is examined. In particular, missions which utilize balloon-borne instruments to study the Venusian and Jovian atmospheres are discussed. Semiconductor development and devices including power sources, ultrastable oscillators, transmitters, antennas, electromechanical devices, and deployment systems are addressed.

  18. 40 CFR 141.81 - Applicability of corrosion control treatment steps to small, medium-size and large water systems.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 23 2011-07-01 2011-07-01 false Applicability of corrosion control treatment steps to small, medium-size and large water systems. 141.81 Section 141.81 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Control of Lead and...

  19. 40 CFR 141.81 - Applicability of corrosion control treatment steps to small, medium-size and large water systems.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Applicability of corrosion control treatment steps to small, medium-size and large water systems. 141.81 Section 141.81 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Control of Lead and...

  20. Estimation of Random Medium Parameters from 2D Post-Stack Seismic Data and Its Application in Seismic Inversion

    NASA Astrophysics Data System (ADS)

    Yang, X.; Zhu, P.; Gu, Y.; Xu, Z.

    2015-12-01

    Small scale heterogeneities of subsurface medium can be characterized conveniently and effectively using a few simple random medium parameters (RMP), such as autocorrelation length, angle and roughness factor, etc. The estimation of these parameters is significant in both oil reservoir prediction and metallic mine exploration. Poor accuracy and low stability existed in current estimation approaches limit the application of random medium theory in seismic exploration. This study focuses on improving the accuracy and stability of RMP estimation from post-stacked seismic data and its application in the seismic inversion. Experiment and theory analysis indicate that, although the autocorrelation of random medium is related to those of corresponding post-stacked seismic data, the relationship is obviously affected by the seismic dominant frequency, the autocorrelation length, roughness factor and so on. Also the error of calculation of autocorrelation in the case of finite and discrete model decreases the accuracy. In order to improve the precision of estimation of RMP, we design two improved approaches. Firstly, we apply region growing algorithm, which often used in image processing, to reduce the influence of noise in the autocorrelation calculated by the power spectrum method. Secondly, the orientation of autocorrelation is used as a new constraint in the estimation algorithm. The numerical experiments proved that it is feasible. In addition, in post-stack seismic inversion of random medium, the estimated RMP may be used to constrain inverse procedure and to construct the initial model. The experiment results indicate that taking inversed model as random medium and using relatively accurate estimated RMP to construct initial model can get better inversion result, which contained more details conformed to the actual underground medium.

  1. Simulations on shifting medium and its application in wireless power transfer system to enhance magnetic coupling

    NASA Astrophysics Data System (ADS)

    Li, Wenwen; Zhang, Yingyi; Yao, Chen; Tang, Houjun

    2016-05-01

    Shifting medium is a kind of an anisotropic but homogeneous metamaterial designed by transformation optics. An object or free space enclosed by the shifting medium could be moved to a certain distance away from the original position. In this paper, we propose a cone-shaped shifting medium shell to move an internal coil to the given position. In this way, the two coils in a wireless power transfer system could be equivalently moved closer; thus, their magnetic coupling is enhanced. The theoretical models and numerical simulations are presented and analyzed to validate the effects of the shifting medium shell. Both ohmic loss and magnetic loss are also considered for practical concerns. Finally, we discuss the simplification of such a shifting medium to facilitate its fabrication.

  2. Low Temperature SQUID for NDE Applications

    NASA Technical Reports Server (NTRS)

    Wincheski, Buzz (Technical Monitor); Selim, Raouf

    2003-01-01

    We have developed a low temperature SuperConducting Quantum Interference Device - SQUID measurement system for detection of defects deep under the surface of aluminum structures using eddy current techniques. The system uses a two dimensional planar inducer with two different excitation frequencies to induce a current in the sample. We have developed a data analysis software program that enabled us to distinguish between round defects (holes), straight defects (slots) and slots close to holes simulating cracks starting from rivets in aluminum structures. We were able to detect defects that are 8mm below the surface. We have also measured the change in phase of the detected signal as a function of depth of the defect. This relationship can be used to determine the depth of hidden flaws. Using this analysis software with the high temperature SQUID system at NASA Langley we were able to detect slots close to holes in layered aluminum sample.

  3. High temperature superconductor materials and applications

    NASA Technical Reports Server (NTRS)

    Doane, George B., III. (Editor); Banks, Curtis; Golben, John

    1991-01-01

    One of the areas concerned itself with the investigation of the phenomena involved in formulating and making in the laboratory new and better superconductor material with enhanced values of critical current and temperature. Of special interest were the chemistry, physical processes, and environment required to attain these enhanced desirable characteristics. The other area concerned itself with producing high temperature superconducting thin films by pulsed laser deposition techniques. Such films are potentially very useful in the detection of very low power signals. To perform this research high vacuum is required. In the course of this effort, older vacuum chambers were maintained and used. In addition, a new facility is being brought on line. This latter activity has been replete with the usual problems of bringing a new facility into service. Some of the problems are covered in the main body of this report.

  4. Medium decoupling of dynamics at temperatures ˜100 K above glass-transition temperature: A case study with (acetamide + lithium bromide/nitrate) melts

    NASA Astrophysics Data System (ADS)

    Guchhait, Biswajit; Daschakraborty, Snehasis; Biswas, Ranjit

    2012-05-01

    Time-resolved fluorescence Stokes shift and anisotropy measurements using a solvation probe in [0.78CH3CONH2 + 0.22{f LiBr + (1-f) LiNO3}] melts reveal a strong decoupling of medium dynamics from viscosity. Interestingly, this decoupling has been found to occur at temperatures ˜50-100 K above the glass transition temperatures of the above melt at various anion concentrations (fLiBr). The decoupling is reflected via the following fractional viscosity dependence (η) of the measured average solvation and rotation times (⟨τs⟩ and ⟨τr⟩, respectively): ⟨τx⟩ ∝ (η/T)p (x being solvation or rotation), with p covering the range, 0.20 < p < 0.70. Although this is very similar to what is known for deeply supercooled liquids, it is very surprising because of the temperature range at which the above decoupling occurs for these molten mixtures. The kinship to the supercooled liquids is further exhibited via p which is always larger for ⟨τr⟩ than for ⟨τs⟩, indicating a sort of translation-rotation decoupling. Multiple probes have been used in steady state fluorescence measurements to explore the extent of static heterogeneity. Estimated experimental dynamic Stokes shift for coumarin 153 in these mixtures lies in the range, 1000 < Δνt/cm-1 < 1700, and is in semi-quantitative agreement with predictions from our semi-molecular theory. The participation of the fluctuating density modes at various length-scales to the observed solvation times has also been investigated.

  5. Constraints on the temperature of the intergalactic medium at z = 8.4 with 21-cm observations

    NASA Astrophysics Data System (ADS)

    Greig, Bradley; Mesinger, Andrei; Pober, Jonathan C.

    2016-02-01

    We compute robust lower limits on the spin temperature, TS, of the z = 8.4 intergalactic medium (IGM), implied by the upper limits on the 21-cm power spectrum recently measured by PAPER-64. Unlike previous studies which used a single epoch of reionization (EoR) model, our approach samples a large parameter space of EoR models: the dominant uncertainty when estimating constraints on TS. Allowing TS to be a free parameter and marginalizing over EoR parameters in our Markov Chain Monte Carlo code 21CMMC, we infer TS ≥ 3 K (corresponding approximately to 1σ) for a mean IGM neutral fraction of bar{x}_{HI}≳ 0.1. We further improve on these limits by folding-in additional EoR constraints based on: (i) the dark fraction in QSO spectra, which implies a strict upper limit of bar{x}_{HI}[z=5.9]≤ 0.06+0.05 (1σ ); and (ii) the electron scattering optical depth, τe = 0.066 ± 0.016 (1σ) measured by the Planck satellite. By restricting the allowed EoR models, these additional observations tighten the approximate 1σ lower limits on the spin temperature to TS ≥ 6 K. Thus, even such preliminary 21-cm observations begin to rule out extreme scenarios such as `cold reionization', implying at least some prior heating of the IGM. The analysis framework developed here can be applied to upcoming 21-cm observations, thereby providing unique insights into the sources which heated and subsequently reionized the very early Universe.

  6. Effect of temperature, pH, and water activity on Mucor spp. growth on synthetic medium, cheese analog and cheese.

    PubMed

    Morin-Sardin, Stéphanie; Rigalma, Karim; Coroller, Louis; Jany, Jean-Luc; Coton, Emmanuel

    2016-06-01

    The Mucor genus includes a large number of ubiquitous fungal species. In the dairy environment, some of them play a technological role providing typical organoleptic qualities to some cheeses while others can cause spoilage. In this study, we compared the effect of relevant abiotic factors for cheese production on the growth of six strains representative of dairy technological and contaminant species as well as of a non cheese related strain (plant endophyte). Growth kinetics were determined for each strain in function of temperature, water activity and pH on synthetic Potato Dextrose Agar (PDA), and secondary models were fitted to calculate the corresponding specific cardinal values. Using these values and growth kinetics acquired at 15 °C on cheese agar medium (CA) along with three different cheese types, optimal growth rates (μopt) were estimated and consequently used to establish a predictive model. Contrarily to contaminant strains, technological strains showed higher μopt on cheese matrices than on PDA. Interestingly, lag times of the endophyte strain were strongly extended on cheese related matrices. This study offers a relevant predictive model of growth that may be used for better cheese production control but also raises the question of adaptation of some Mucor strains to the cheese. PMID:26919819

  7. Understanding Electrocatalytic Pathways in Low and Medium Temperature Fuel Cells: Synchrotron-based In Situ X-Ray Absorption Spectroscopy

    SciTech Connect

    Mukerjee, S.; Ziegelbauer, J; Arruda, T; Ramaker, D; Shyam, B

    2008-01-01

    Over the last few decades, researchers have made significant developments in producing more advanced electrocatalytic materials for power generation applications. For example, traditional fuel cell catalysts often involve high-priced precious metals such as Pt. However, in order for fuel cells to become commercially viable, there is a need to reduce or completely remove precious metal altogether. As a result, a myriad of novel, unconventional materials have been explored such as chalcogenides, porphyrins, and organic-metal-macrocycles for low/medium temperature fuel cells as well as enzymatic and microbial fuel cells. As these materials increasingly become more complex, researchers often find themselves in search of new characterization methods, especially those which are allow in situ and operando measurements with element specificity. One such method that has received much attention for analysis of electrocatalytic materials is X-ray absorption spectroscopy (XAS). XAS is an element specific, core level absorption technique which yields structural and electronic information. As a core electron method, XAS requires an extremely bright source, hence a synchrotron. The resulting intensity of synchrotron radiation allow for experiments to be conducted in situ, under electrochemically relevant conditions. Although a bulk-averaging technique requiring rigorous mathematical manipulation, XAS has the added benefit that it can probe materials which possess no long range order. This makes it ideal to characterize nano-scale electrocatalysts. XAS experiments are conducted by ramping the X-ray photon energy while measuring absorption of the incident beam the sample or by counting fluorescent photons released from a sample due to subsequent relaxation. Absorption mode XAS follows the Beer-Lambert Law, {mu}x = log(I{sub 0}/I{sub t}) (1) where {mu} is the absorption coefficient, x is the sample thickness and I{sub 0} and I{sub t} are the intensities of the incident and

  8. Application of inverse heat conduction problem on temperature measurement

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Zhou, G.; Dong, B.; Li, Q.; Liu, L. Q.

    2013-09-01

    For regenerative cooling devices, such as G-M refrigerator, pulse tube cooler or thermoacoustic cooler, the gas oscillating bring about temperature fluctuations inevitably, which is harmful in many applications requiring high stable temperatures. To find out the oscillating mechanism of the cooling temperature and improve the temperature stability of cooler, the inner temperature of the cold head has to be measured. However, it is difficult to measure the inner oscillating temperature of the cold head directly because the invasive temperature detectors may disturb the oscillating flow. Fortunately, the outer surface temperature of the cold head can be measured accurately by invasive temperature measurement techniques. In this paper, a mathematical model of inverse heat conduction problem is presented to identify the inner surface oscillating temperature of cold head according to the measured temperature of the outer surface in a GM cryocooler. Inverse heat conduction problem will be solved using control volume approach. Outer surface oscillating temperature could be used as input conditions of inverse problem and the inner surface oscillating temperature of cold head can be inversely obtained. A simple uncertainty analysis of the oscillating temperature measurement also will be provided.

  9. Comparison of Local Scale Measured and Modeled Brightness Temperatures and Snow Parameters from the CLPX 2003 by Means of a Dense Medium Radiative Transfer Theory Model

    NASA Technical Reports Server (NTRS)

    Tedescol, Marco; Kim, Edward J.; Cline, Don; Graf, Tobias; Koike, Toshio; Armstrong, Richard; Brodzik, Mary J.; Hardy, Janet

    2004-01-01

    Microwave remote sensing offers distinct advantages for observing the cryosphere. Solar illumination is not required, and spatial and temporal coverage are excellent from polar-orbiting satellites. Passive microwave measurements are sensitive to the two most useful physical quantities for many hydrological applications: physical temperature and water content/state. Sensitivity to the latter is a direct result of the microwave sensitivity to the dielectric properties of natural media, including snow, ice, soil (frozen or thawed), and vegetation. These considerations are factors motivating the development of future cryospheric satellite remote sensing missions, continuing and improving on a 26-year microwave measurement legacy. Perhaps the biggest issues regarding the use of such satellite measurements involve how to relate parameter values at spatial scales as small as a hectare to observations with sensor footprints that may be up to 25 x 25 km. The NASA Cold-land Processes Field Experiment (CLPX) generated a dataset designed to enhance understanding of such scaling issues. CLPX observations were made in February (dry snow) and March (wet snow), 2003 in Colorado, USA, at scales ranging from plot scale to 25 x 25 km satellite footprints. Of interest here are passive microwave observations from ground-based, airborne, and satellite sensors, as well as meteorological and snowpack measurements that will enable studies of the effects of spatial heterogeneity of surface conditions on the observations. Prior to performing such scaling studies, an evaluation of snowpack forward modelling at the plot scale (least heterogeneous scale) is in order. This is the focus of this paper. Many forward models of snow signatures (brightness temperatures) have been developed over the years. It is now recognized that a dense medium radiative transfer (DMRT) treatment represents a high degree of physical fidelity for snow modeling, yet dense medium models are particularly sensitive to

  10. Use of ethyl lactate to extract bioactive compounds from Cytisus scoparius: Comparison of pressurized liquid extraction and medium scale ambient temperature systems.

    PubMed

    Lores, Marta; Pájaro, Marta; Álvarez-Casas, Marta; Domínguez, Jorge; García-Jares, Carmen

    2015-08-01

    An important trend in the extraction of chemical compounds is the application of new environmentally friendly, food grade solvents. Ethyl lactate (ethyl 2-hydroxypropanoate), produced by fermentation of carbohydrates, is miscible with both hydrophilic and hydrophobic compounds being a potentially good solvent for bioactive compounds. Despite its relatively wide use as a general solvent, the utilization of ethyl lactate as an extraction solvent has only recently been considered. Here, we evaluate the possible use of ethyl lactate to extract phenolic compounds from wild plants belonging to Cytisus scoparius, and we compare the characteristics of the extracts obtained by Pressurized Solvent Extraction (the total phenolics content, the antioxidant activity and the concentration of the major polyphenols) with those of other extracts obtained with methanol. In order to explore the industrial production of the ethyl lactate Cytisus extract, we also evaluate medium scale ambient temperature setups. The whole plant and the different parts (flowers, branches, and seed pods) were evaluated separately as potential sources of polyphenols. All extracts were analyzed by LC-MS/MS for accurate identification of the major polyphenols. Similar phenolic profiles were obtained when using ethyl lactate or methanol. The main bioactives found in the Cytisus extract were the non-flavonoid phenolic compounds caffeic and protocatechuic acids and 3,4-dihydroxybenzaldehyde; the flavonoids rutin, kaempferol and quercetin; the flavones chrysin, orientin and apigenin; and the alkaloid lupanine. Regarding the comparison of the extraction systems, although the performance of the PLE was much better than that of the ambient-temperature columns, the energy consumption was also much higher. Ethyl lactate has resulted an efficient extraction solvent for polyphenols from C. scoparius, yielding extracts with high levels of plant phenolics and antioxidant activity. The antimicrobial activity of these

  11. Layered machinable ceramics for high temperature applications

    SciTech Connect

    Barsoum, M.W.; Brodkin, D.; El-Raghy, T.

    1997-03-01

    Recently the authors reported on the fabrication and characterization of a layered ternary compound Ti{sub 3}SiC{sub 2}, that was found to combine many of the best attributes of metals and ceramics. Like metals it is an excellent electric and thermal conductor, easily machinable, relatively soft, not susceptible to thermal shock and behaves plastically at higher temperatures. Like ceramics it is oxidation resistant, refractory, and, most importantly, it maintains its strength to temperatures that render the best superalloys available today unusable. Upon realizing the remarkable properties exhibited by Ti{sub 3}SiC{sub 2} the authors carried out a literature search for other compounds with the same chemistry. They found one only, namely: Ti{sub 3}GeC{sub 2} which has properties that are very similar to Ti{sub 3}SiC{sub 2}. The purpose of this paper is two-fold. The first is to demonstrate the similarities between the properties of the H-phases, Ti{sub 3}GeC{sub 2} and Ti{sub 3}SiC{sub 2}. The second is to present some compelling microstructural evidence that indicates that these compounds behave as polycrystalline nanolaminates. To that effect the authors fabricated and characterized the following H-phases: Ti{sub 2}AlC, Ti{sub 2}AlN, Ti{sub 2}GeC and as well as Ti{sub 3}GeC{sub 2}. In addition they fabricated V{sub 2}AlC, Ta{sub 2}AlC, and Nb{sub 2}AlC and tested their machinability.

  12. SiC device development for high temperature sensor applications

    NASA Technical Reports Server (NTRS)

    Shor, J. S.; Goldstein, David; Kurtz, A. D.; Osgood, R. M.

    1992-01-01

    Progress made in the processing and characterization of 3C-SiC for high temperature sensor applications is reviewed. Piezoresistance properties of silicon carbide and the temperature coefficient of resistivity of n-type beta-SiC are presented. In addition, photoelectrical etching and dopant selective etch-stops in SiC and high temperature Ohmic contacts for n-type beta-SiC sensors are discussed.

  13. SiC device development for high temperature sensor applications

    NASA Astrophysics Data System (ADS)

    Shor, J. S.; Goldstein, David; Kurtz, A. D.; Osgood, R. M.

    1992-09-01

    Progress made in the processing and characterization of 3C-SiC for high temperature sensor applications is reviewed. Piezoresistance properties of silicon carbide and the temperature coefficient of resistivity of n-type beta-SiC are presented. In addition, photoelectrical etching and dopant selective etch-stops in SiC and high temperature Ohmic contacts for n-type beta-SiC sensors are discussed.

  14. Effect of temperature and water activity on gene expression and aflatoxin biosynthesis in Aspergillus flavus on almond medium.

    PubMed

    Gallo, Antonia; Solfrizzo, Michele; Epifani, Filomena; Panzarini, Giuseppe; Perrone, Giancarlo

    2016-01-18

    Almonds are among the commodities at risk of aflatoxin contamination by Aspergillus flavus. Temperature and water activity are the two key determinants in pre and post-harvest environments influencing both the rate of fungal spoilage and aflatoxin production. Varying the combination of these parameters can completely inhibit or fully activate the biosynthesis of aflatoxin, so it is fundamental to know which combinations can control or be conducive to aflatoxin contamination. Little information is available about the influence of these parameters on aflatoxin production on almonds. The objective of this study was to determine the influence of different combinations of temperature (20 °C, 28 °C, and 37 °C) and water activity (0.90, 0.93, 0.96, 0.99 aw) on growth, aflatoxin B1 (AFB1) production and expression of the two regulatory genes, aflR and aflS, and two structural genes, aflD and aflO, of the aflatoxin biosynthetic cluster in A. flavus grown on an almond medium solidified with agar. Maximum accumulation of fungal biomass and AFB1 production was obtained at 28 °C and 0.96 aw; no fungal growth and AFB1 production were observed at 20 °C at the driest tested conditions (0.90 and 0.93 aw). At 20° and 37 °C AFB1 production was 70-90% lower or completely suppressed, depending on aw. Reverse transcriptase quantitative PCR showed that the two regulatory genes (aflR and aflS) were highly expressed at maximum (28 °C) and minimum (20 °C and 37 °C) AFB1 production. Conversely the two structural genes (aflD and aflO) were highly expressed only at maximum AFB1 production (28 °C and 0.96-0.99 aw). It seems that temperature acts as a key factor influencing aflatoxin production which is strictly correlated to the induction of expression of structural biosynthesis genes (aflD and aflO), but not to that of aflatoxin regulatory genes (aflR and aflS), whose functional products are most likely subordinated to other regulatory processes acting at post-translational level

  15. Austenitic stainless steel for high temperature applications

    DOEpatents

    Johnson, Gerald D.; Powell, Roger W.

    1985-01-01

    This invention describes a composition for an austenitic stainless steel which has been found to exhibit improved high temperature stress rupture properties. The composition of this alloy is about (in wt. %): 12.5 to 14.5 Cr; 14.5 to 16.5 Ni; 1.5 to 2.5 Mo; 1.5 to 2.5 Mn; 0.1 to 0.4 Ti; 0.02 to 0.08 C; 0.5 to 1.0 Si; 0.01 maximum, N; 0.02 to 0.08 P; 0.002 to 0.008 B; 0.004-0.010 S; 0.02-0.05 Nb; 0.01-0.05 V; 0.005-0.02 Ta; 0.02-0.05 Al; 0.01-0.04 Cu; 0.02-0.05 Co; 0.03 maximum, As; 0.01 maximum, O; 0.01 maximum, Zr; and with the balance of the alloy being essentially iron. The carbon content of the alloy is adjusted such that wt. % Ti/(wt. % C+wt. % N) is between 4 and 6, and most preferably about 5. In addition the sum of the wt. % P+wt. % B+wt. % S is at least 0.03 wt. %. This alloy is believed to be particularly well suited for use as fast breeder reactor fuel element cladding.

  16. Engineered carbon foam for temperature control applications

    NASA Astrophysics Data System (ADS)

    Almajali, Mohammad Rajab

    pressure within the foam matrix were investigated. These factors lowered the heat transfer rate considerably and the melting area was reduced by more than 23%. Two samples, coated and uncoated carbon foam, were infiltrated with PCM and subjected to a uniform heat load test in a vacuum. The coated foam showed excellent performance compared to the uncoated foam. (iii) Finally, the new engineered carbon foam was used as a heat sink and heat exchanger in a thermoelectric cooler for a cooling vest application. Using carbon foam as the core material for this application, the effective transfer of heat was significantly increased while reducing the size and weight of the heat exchanger.

  17. Production of thermo-alkali-stable xylanase by a novel polyextremophilic Bacillus halodurans TSEV1 in cane molasses medium and its applicability in making whole wheat bread.

    PubMed

    Kumar, Vikash; Satyanarayana, T

    2014-06-01

    A high titre of thermo-alkali-stable xylanase was attained in cane molasses medium. When the culture variables for endoxylanase production were optimized [cane molasses 7 %, soluble alkaline extract of wheat bran (SAE-WB) 37 % and ammonium chloride 0.30 %], a 4.5-fold enhancement in xylanase production (69 U ml(-1)) was achieved as compared to that in the unoptimized medium (15 U ml(-1)). The enzyme titre attained in shake flasks could be sustained in a 7-l laboratory bioreactor. An activity band corresponding to 40 kDa was visualized on SDS-PAGE zymogram analysis. The enzyme has broad range of pH and temperature for activity with optima at 9.0 and 80 °C, and stable between pH 4.0 and 11.0 with 85 % retention of activity. It has T 1/2 of 40 and 15 min at 70 and 80 °C. The enzyme is halotolerant since it displays activity in the presence of salt up to 15 %, and remains 100 % active in the absence of salt. The supplementation of whole wheat dough with xylanase improves antistaling property, reducing sugar content, bread volume with prebiotic xylooligosaccharides in bread. This is the first report on xylanase production in cane molasses medium with SAE-WB as the inducer and its applicability in whole wheat bread making that improves human health. PMID:24297158

  18. Potential Applications of an Integrated Seismic, Tilt, and Temperature Instrument

    NASA Astrophysics Data System (ADS)

    Bainbridge, Geoffrey; Parker, Tim; Karimi, Sepideh; Devanney, Peter

    2016-04-01

    Force feedback seismometers provide mass position outputs which represent the time-averaged feedback force applied to each inertial mass, in order to cancel external forces and keep it balanced at its center point. These external forces are primarily due to tilt and temperature. In a symmetric triaxial seismometer, tilt and temperature effects can be distinguished because temperature affects all 3 axes equally whereas tilt causes a different force on each axis. This study analyzes the resolution of tilt and temperature signals that can be obtained from a force-feedback seismometer, and the potential applicability of this data to applications such as volcano monitoring and cap rock integrity monitoring. Also the synergy of a combined seismic, tilt, and temperature instrument is considered.

  19. A fiber optic temperature sensor for aerospace applications

    NASA Astrophysics Data System (ADS)

    Jensen, Stephen C.; Tilstra, Shelle D.; Barnabo, Geoffrey A.; Thomas, David C.; Phillips, Richard W.

    1991-02-01

    A fiber-optic temperature sensor has been developed for aerospace applications on the basis of the time rate of decay (TRD) principle, with a view to an operational temperature range of -60 to 350 C. This TRD system has completed qualification testing and will then undergo flight tests. Attention is presently given to the design and performance of four low temperature sensors that are subelements of the larger sensor system; in order to convert analog signals into over/under temperature indications, simple comparators are implemented in software.

  20. Omega transmission lines with applications to effective medium models of metamaterials

    NASA Astrophysics Data System (ADS)

    Vehmas, J.; Hrabar, S.; Tretyakov, S.

    2014-04-01

    In this paper, we introduce the concept of transmission lines with inherent bi-anisotropy and establish an analogy between these lines and volumetric bi-anisotropic materials. In particular, we find under what conditions a periodically loaded transmission line can be treated as an effective omega medium. Two example circuits are introduced and analyzed. The results have two-fold implications: opening a route to emulate electromagnetic properties of bi-anisotropic omega media using transmission-line meshes and understanding and improving effective medium models of composite materials with the use of effective circuit models of unit cells.

  1. Transmission medium and full fiber-optic setup for quantum key distribution applications

    NASA Astrophysics Data System (ADS)

    Tsakiris, Stavros I.; Uzunoglu, Nikolaos K.

    2006-12-01

    A fiber-optic-based coupled waveguide transmission medium is proposed to distribute secret keys in a single-photon polarization-based quantum cryptography setup. Polarization maintenance properties and coupling phenomena of the transmission medium are exploited to achieve accuracy and security of the transferred key. Elliptic fibers and fiber couplers are used to prepare the transmitted photons at the sender as well as analyze them at the receiver. The uniqueness of the setup stands on the exclusive use of fiber-optic components, enabling its construction on a single fiber line.

  2. Magnetic field penetration into a 3D ordered Josephson medium and applicability of the bean model

    NASA Astrophysics Data System (ADS)

    Zelikman, M. A.

    2014-11-01

    The results of calculation of penetration of an external magnetic field into a 3D ordered Josephson medium, based on analysis of modification of the configuration in the direction of the decrease in its Gibbs potential, are reported. When the external field slightly exceeds the stability threshold, the Meissner configuration is transformed into a periodic sequence of linear vortices, which are parallel to the boundary of the medium and are located at a certain distance from it. There exists a critical value I C separating two possible regimes of penetration of the external magnetic field into the medium. For I > I C, for any value of the external field, a finite-length boundary current configuration appears, which completely compensates the external field in the bulk of the sample. At the sample boundary, the field decreases with increasing depth almost linearly. The values of the slope of the magnetic field dependence are rational fractions, which remain constant in finite intervals of I. When the value of I exceeds the upper boundary of such an interval, the slope increases and assumes the value of another rational fraction. If, however, I < I C, such a situation takes place only up to a certain value of external field H max. For higher values, the field penetrates into the medium to an infinite depth. These results lead to the conclusion that the Bean assumptions are violated and that Bean's model is inapplicable for analyzing the processes considered here.

  3. A standardized diode cryogenic temperature sensor for aerospace applications

    NASA Astrophysics Data System (ADS)

    Courts, Samuel Scott

    2016-03-01

    The model DT-670-SD cryogenic diode temperature sensor, manufactured by Lake Shore Cryotronics, Inc. has been used on numerous aerospace space missions since its introduction nearly 15 years ago. While the sensing element is a diode, it is operated in a non-standard manner when used as a temperature sensor over the 1.4-500 K temperature range. For this reason, the NASA and MIL-type test and performance standards designed to ensure high reliability of diode aerospace parts don't properly define the inspection and test protocol for the DT-670-SD temperature sensor as written. This requires each aerospace application to develop unique test and inspection protocols for the project, typically for a small number of sensors, resulting in expensive sensors with a long lead time. With over 30 years of experience in supplying cryogenic temperature sensors for aerospace applications, Lake Shore has developed screening and qualification inspection and test protocols to provide "commercial off-the-shelf (COTS)" DT-670-SD temperature sensors that should meet the requirements of most high-reliability applications including aerospace. Parts from acceptance and qualified lots will be available at a base sensor level with the ability to specify an interchangeability tolerance, calibration range, mounting adaptor, and/or lead extension for final configuration. This work presents details of this acceptance and qualification inspection and test protocol as well as performance characteristics of the DT-670-SD cryogenic temperature sensors when inspected and tested to this protocol.

  4. Holding equine oocytes in a commercial embryo-holding medium: New perspective on holding temperature and maturation time.

    PubMed

    Dini, Pouya; Bogado Pascottini, Osvaldo; Ducheyne, Kaatje; Hostens, Miel; Daels, Peter

    2016-09-15

    In the present study, we examined the effect of holding equine oocytes in Syngro embryo holding medium (EHM) overnight at either 4 °C, 17 °C, or 22 °C to 25 °C, on the time to maturation and developmental competence. We also examined the effect of placing denuded oocyte without extruded polar body back in maturation condition on subsequent maturation rate. In experiment 1, cumulus-oocyte complexes (COCs) were recovered postmortem and placed in EHM at 22 °C to 25 °C for 18 to 20 hours (OH) or placed directly in maturation (DM). The maturation rate was assessed after 22, 24, or 28 hours of culture. After denuding cumulus cells at 22 or 24 hours, oocytes without obvious polar body were placed back into culture and reassessed at subsequent time points. At 22 hours, a higher proportion of oocytes placed in OH achieved nuclear maturation than those placed in DM (63% and 37%, respectively, P = 0.008). At 24 and 28 hours, no significant differences in the % MII stage oocytes were observed between OH and DM. The nuclear maturation rate for OH oocytes was similar at 22, 24, and 28 hours, indicating that the maximum maturation rate was reached at an earlier time than that in DM. Oocytes fertilized by intracytoplasmic sperm injection resulted in a 7.1% and 6.3% blastocyst rate for OH and DM, respectively. Denuding oocytes after 22 hours or more of culture did not have an adverse effect on the final nuclear maturation rate. After 28 hours of culture, the same nuclear maturation rate (MII) was reached for nondenuded oocytes and oocytes denuded after 22 hours of 24 hours of culture. In experiment 2, COCs were held overnight at room temperature in EHM, then placed in maturation for 20, 22, and 28 hours. Nuclear maturation rate was significantly lower at 20 hours than 22 and 28 hours of culture and was similar at 22 and 28 hours, suggesting that at least 22 hours of culture is required to reach maximal maturation rate for stored oocytes (43%, 62%, and 65% at 20, 22

  5. Application for temperature and humidity monitoring of data center environment

    NASA Astrophysics Data System (ADS)

    Albert, Ş.; Truşcǎ, M. R. C.; Soran, M. L.

    2015-12-01

    The technology and computer science registered a large development in the last years. Most systems that use high technologies require special working conditions. The monitoring and the controlling are very important. The temperature and the humidity are important parameters in the operation of computer systems, industrial and research, maintaining it between certain values to ensure their proper functioning being important. Usually, the temperature is maintained in the established range using an air conditioning system, but the humidity is affected. In the present work we developed an application based on a board with own firmware called "AVR_NET_IO" using a microcontroller ATmega32 type for temperature and humidity monitoring in Data Center of INCDTIM. On this board, temperature sensors were connected to measure the temperature in different points of the Data Center and outside of this. Humidity monitoring is performed using data from integrated sensors of the air conditioning system, thus achieving a correlation between humidity and temperature variation. It was developed a software application (CM-1) together with the hardware, which allows temperature monitoring and register inside Data Center and trigger an alarm when variations are greater with 3°C than established limits of the temperature.

  6. Industrial applications of MHD high temperature air heater technology

    NASA Astrophysics Data System (ADS)

    Saari, D. P.; Fenstermacher, J. E.; White, L. R.; Marksberry, C. L.

    1981-12-01

    The MHD high temperature air heater (HTAH) requires technology beyond the current state-of-the-art of industrial regenerative heaters. Specific aspects of HTAH technology which may find other application include refractory materials and valves resistant to the high temperature, corrosive, slag-bearing gas, materials resistant to cyclic thermal stresses, high temperature support structures for the cored brick bed, regenerative heater operating techniques for preventing accumulation of slag in the heater, and analytical tools for computing regenerative heater size, cost, and performance. Areas where HTAH technology may find application include acetylene/ethylene production processes, flash pyrolysis of coal, high temperature gas reactors, coal gasification processes, various metallurgical processes, waste incineration, and improvements to existing regenerator technology such as blast furnace stoves and glass tank regenerators.

  7. Development of silicon carbide semiconductor devices for high temperature applications

    NASA Technical Reports Server (NTRS)

    Matus, Lawrence G.; Powell, J. Anthony; Petit, Jeremy B.

    1991-01-01

    The semiconducting properties of electronic grade silicon carbide crystals, such as wide energy bandgap, make it particularly attractive for high temperature applications. Applications for high temperature electronic devices include instrumentation for engines under development, engine control and condition monitoring systems, and power conditioning and control systems for space platforms and satellites. Discrete prototype SiC devices were fabricated and tested at elevated temperatures. Grown p-n junction diodes demonstrated very good rectification characteristics at 870 K. A depletion-mode metal-oxide-semiconductor field-effect transistor was also successfully fabricated and tested at 770 K. While optimization of SiC fabrication processes remain, it is believed that SiC is an enabling high temperature electronic technology.

  8. Alloys based on NiAl for high temperature applications

    NASA Technical Reports Server (NTRS)

    Vedula, K. M.; Pathare, V.; Aslanidis, I.; Titran, R. H.

    1984-01-01

    The NiAl alloys for potential high temperature applications were studied. Alloys were prepared by powder metallurgy techniques. Flow stress values at slow strain rates and high temperatures were measured. Some ternary alloying additions (Hf, Ta and Nb) were identified. The mechanism of strengthening in alloys containing these additions appears to be a form of particle dislocation interaction. The effects of grain size and stoichiometry in binary alloys are also presented.

  9. Cryocooler applications for high-temperature superconductor magnetic bearings.

    SciTech Connect

    Niemann, R. C.

    1998-05-22

    The efficiency and stability of rotational magnetic suspension systems are enhanced by the use of high-temperature superconductor (HTS) magnetic bearings. Fundamental aspects of the HTS magnetic bearings and rotational magnetic suspension are presented. HTS cooling can be by liquid cryogen bath immersion or by direct conduction, and thus there are various applications and integration issues for cryocoolers. Among the numerous cryocooler aspects to be considered are installation; operating temperature; losses; and vacuum pumping.

  10. A standardized Cernox™ cryogenic temperature sensor for aerospace applications

    NASA Astrophysics Data System (ADS)

    Courts, Samuel Scott

    2014-11-01

    The success of any aerospace mission depends upon the reliability of the discrete components comprising the instrument. To this end, many test standards have been developed to define test protocols and methods for the parts used in these missions. To date, no recognized MIL-type standard exists for cryogenic temperature sensors that are used from room temperature to 20 K or below. The aerospace applications utilizing these sensors require the procuring entity to develop a specification which the sensor manufacturer uses to screen and qualify a single build lot for flight use. The individual applications often require only a small number of sensors with the end result being a relatively high cost and long delivery time. Over the past two decades, Lake Shore Cryotronics, Inc. has worked with many aerospace companies to supply Cernox™ cryogenic temperature sensors for numerous missions. The experience gained from this work has led to the development of a manufacturing and test protocol resulting in 'off-the-shelf' cryogenic temperature sensors that should meet the requirements for many aerospace applications. Sensors will be available at the base part level with the ability to configure the delivered part with regard to lead wire material, package adapter, lead wire extensions, and calibration as appropriate or necessary for the application. This work presents details of this manufacturing, inspection, and test protocol as well as performance characteristics of Cernox™ temperature sensors when inspected and tested to this protocol.

  11. Emerging applications of high temperature superconductors for space communications

    NASA Technical Reports Server (NTRS)

    Heinen, Vernon O.; Bhasin, Kul B.; Long, Kenwyn J.

    1990-01-01

    Proposed space missions require longevity of communications system components, high input power levels, and high speed digital logic devices. The complexity of these missions calls for a high data bandwidth capacity. Incorporation of high temperature superconducting (HTS) thin films into some of these communications system components may provide a means of meeting these requirements. Space applications of superconducting technology has previously been limited by the requirement of cooling to near liquid helium temperatures. Development of HTS materials with transition temperatures above 77 K along with the natural cooling ability of space suggest that space applications may lead the way in the applications of high temperature superconductivity. In order for HTS materials to be incorporated into microwave and millimeter wave devices, the material properties such as electrical conductivity, current density, surface resistivity and others as a function of temperature and frequency must be well characterized and understood. The millimeter wave conductivity and surface resistivity were well characterized, and at 77 K are better than copper. Basic microwave circuits such as ring resonators were used to determine transmission line losses. Higher Q values than those of gold resonator circuits were observed below the transition temperature. Several key HTS circuits including filters, oscillators, phase shifters and phased array antenna feeds are feasible in the near future. For technology to improve further, good quality, large area films must be reproducibly grown on low dielectric constant, low loss microwave substrates.

  12. Medium optimization by combination of response surface methodology and desirability function: an application in glutamine production.

    PubMed

    Li, Jinshan; Ma, Cuiqing; Ma, Yanhe; Li, Yan; Zhou, Wei; Xu, Ping

    2007-03-01

    An optimization strategy based on desirability function approach (DFA) together with response surface methodology (RSM) has been used to optimize production medium in L-glutamine fermentation. Fermentation problems often force to reach a compromise between different experimental variables in order to achieve the most suitable strategy applying in industrial production. The importance of the use of multi-objective optimization methods lies in the ability to cope with this kind of problems. A sequential RSM with different combinations of glucose and (NH(4))(2)SO(4) was performed to attain the optimal medium (OM-1) in glutamine production. Based on the result of RSM and the evaluation of production cost, a more economical optimal medium (OM-2) was obtained with the aid of DFA. In DFA study, glutamate, the main by-product in glutamine fermentation as another response was considered. Compared with OM-1 in validated experiment, similar amounts of glutamine were obtained in OM-2 while the concentration of glutamate and the production cost decreased by 53.6 and 7.1%, respectively. PMID:17119957

  13. Noncontact temperature measurement of aluminized polymer for space applications

    NASA Astrophysics Data System (ADS)

    Pollard, William, Jr.; Hannas, Benjamin

    2002-03-01

    An existing fiber-optic/infrared (F-O/IR) temperature measurement system was adapted to measure the surface temperature of a thin-film aluminized polymer. The polymer under study, Kapton by Dupont, is used commonly in the aerospace industry for applications such as solar sails and solar shields. A cold plate was developed and implemented to control environmental effects on infrared data. Spectral characterization of the optical properties of Kapton was conducted to improve measurement accuracy. The instrument provides a non-contact means for accurate temperature measurement of very thin polymer membranes without distorting surface contour.

  14. Low-speed aerodynamic characteristics of a 13 percent thick medium speed airfoil designed for general aviation applications

    NASA Technical Reports Server (NTRS)

    Mcghee, R. J.; Beasley, W. D.

    1979-01-01

    Wind tunnel tests were conducted to determine the low speed, two dimensional aerodynamic characteristics of a 13percent thick medium speed airfoil designed for general aviation applications. The results were compared with data for the 13 percent thick low speed airfoil. The tests were conducted over a Mach number range from 0.10 to 0.32, a chord Reynolds number range from 2.0 x 10 to the 6th power to 12.0 x 10 to the 6th power, and an angle of attack frange from about -8 deg to 10 deg. The objective of retaining good high-lift low speed characteristics for an airfoil designed to have good medium speed cruise performance was achieved.

  15. Low-speed aerodynamic characteristics of a 17-percent-thick medium speed airfoil designed for general aviation applications

    NASA Technical Reports Server (NTRS)

    Mcghee, R. J.; Beaseley, W. D.

    1980-01-01

    Wind tunnel tests were conducted to determine the low speed two dimensional aerodynamic characteristics of a 17 percent thick medium speed airfoil (MS(1)-0317) designed for general aviation applications. The results were compared with data for the 17 percent thick low speed airfoil (LS(1)-0417) and the 13 percent thick medium speed airfoil (MS(1)-0313). Theoretical predictions of the drag rise characteristics of this airfoil are also provided. The tests were conducted in the Langley low turbulence pressure tunnel over a Mach number range from 0.10 to 0.32, a chord Reynolds number range from 2 million to 12 million, and an angle of attack range from about -8 to 20 deg.

  16. Space applications for high temperature superconductivity - Brief review

    NASA Technical Reports Server (NTRS)

    Krishen, Kumar

    1990-01-01

    An overview is presented of materials and devices based on high-temperature superconductivity (HTS) that could have useful space-oriented applications. Of specific interest are applications of HTS technologies to mm and microwave systems, spaceborne and planet-surface sensors, and to magnetic subsystems for robotic, rescue, and docking maneuvers. HTS technologies can be used in optoelectronics, magnetic-field detectors, antennae, transmission/delay lines, and launch/payload coils.

  17. Metal-Coated Optical Fibers for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Zeakes, Jason; Murphy, Kent; Claus, Richard; Greene, Jonathan; Tran, Tuan

    1996-01-01

    This poster will highlight on-going research at the Virginia Tech Fiber & Electro-Optics Research Center (FEORC) in the area of thin films on optical fibers. Topics will include the sputter deposition of metals and metal; alloys onto optical fiber and fiber optic sensors for innovative applications. Specific information will be available on thin film fiber optic hydrogen sensors, corrosion sensors, and metal-coated optical fiber for high temperature aerospace applications.

  18. Soft ferrite materials for magnetic temperature transducers and applications

    NASA Astrophysics Data System (ADS)

    Miclea, C.; Tanasoiu, C.; Miclea, C. F.; Gheorghiu, A.; Tanasoiu, V.

    2005-04-01

    Soft ferrites in the CuZnTi system, having the formula Cu 1-xZn xTi yFe 2-yO 4, with 0.50⩽ x⩽0.60 and 0.00⩽ y⩽0.05 were investigated as a function of composition, sintering temperature and cooling speed, in order to obtain materials with controlled TC and very high change rate of permeability with temperature around their TC. The effect of Zn and Ti additions was a drastic change of the Curie temperature with about 10-12 °C for each atomic percent of Zn and Ti introduced into the spinel lattice while the cooling speed changed the behaviour of magnetic permeability with temperature around the Curie point. An application using such magnetic temperature sensors for a thermostat is presented.

  19. Common rectifier diodes in temperature measurement applications below 50 K

    NASA Astrophysics Data System (ADS)

    Järvelä, J.; Stenvall, A.; Mikkonen, R.

    2010-06-01

    In this paper we studied the use of common electronic semiconductor diodes in temperature measurements at cryogenic atmosphere. The motivation for this is the high price of calibrated cryogenic temperature sensors since there are some applications, like quench detection, in which a cheaper and a less accurate sensor would suffice. We measured the forward voltage as a function of temperature, Vf(T), of several silicon rectifier diodes to determine the accuracy and interchangeability of the diodes. The experimental results confimed that Vf(T) of common rectifier diodes are similar to cryogenic sensor diodes, but the variability between two samples is much larger. The interchangeability of the diodes proved to be poor if absolute temperatures are to be measured. However for sensing changes in temperature they proved to be adequate and thus can be used to measure e.g. quench propagation or sense quench ignition at multiple locations with cheap price.

  20. Fiber Bragg Grating Temperature Sensor for Defence and Industrial Applications

    NASA Astrophysics Data System (ADS)

    Gebru, Haftay Abadi; Padhy, B. B.

    2011-10-01

    This paper presents the design and development of fiber Bragg grating (FBG) temperature sensor suitable for naval applications like temperature monitoring of onboard ships. The Bragg gratings used here have a reflection Bragg wavelength of 1550 nm and are inscribed by phase mask technique using ultraviolet (UV) laser beam at 255.3 nm. The high-resolution temperature sensor has been designed and developed based on the principle of converting the strain to temperature. This is achieved by using bimetallic configuration. Here lead and tungsten metals are used. The expansion of lead is concentrated on the Bragg grating, thus imparting strain on it. The wavelength shift with change of temperature is recorded with optical spectrum analyzer. The minimum temperature that could be measured accurately by the sensor with repeatability is of the order of 10-2. We have achieved thermal sensitivity of 46 pm/°C and 72 pm/°C for sensor lengths (length of the metallic strips) of 60 mm and 100 mm respectively. The thermal sensitivity achieved is approximately 3.5 times and 5.5 times that of bare FBG with thermal sensitivity of 13 pm/°C for the respective sensor lengths. This type of sensor can play vital role in defence and industrial applications like monitoring fresh water/lubricating oil temperatures of machinery in onboard ships, temperature monitoring of airframe of the aircraft, aircraft engine control system sensors, temperature measurement of hot gases from propellant combustion to protect the rocket motor casing, monitoring and control of temperature of copper bars of the power generators etc.

  1. Non-Darcy natural convection from a vertical plate with a uniform wall temperature and concentration in a doubly stratified porous medium

    NASA Astrophysics Data System (ADS)

    Srinivasacharya, D.; Surender, O.

    2015-07-01

    In this paper, non-similarity solutions for natural convection heat and mass transfer along a vertical plate with a uniform wall temperature and concentration in a doubly stratified porous medium saturated by a fluid are obtained. The Darcy-Forchheimer-based model is employed to describe the flow in the porous medium. The nonlinear governing equations and their associated boundary conditions are initially cast into dimensionless forms by using pseudo-similarity variables. The resulting system of nonlinear partial differential equations is then solved numerically by using the Keller-box method. The effects of the buoyancy parameter, Forchheimer number, and thermal and solutal stratification parameters on the dimensionless velocity, temperature, concentration, and heat and mass transfer coefficients are studied.

  2. New application of temperature-dependent modelling of high temperature superconductors: Quench propagation and pulse magnetization

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Matsuda, Koichi; Coombs, T. A.

    2012-08-01

    We present temperature-dependent modeling of high-temperature superconductors (HTS) to understand HTS electromagnetic phenomena where temperature fluctuation plays a nontrivial role. Thermal physics is introduced into the well-developed H-formulation model, and the effect of temperature-dependent parameters is considered. Based on the model, we perform extensive studies on two important HTS applications: quench propagation and pulse magnetization. A micrometer-scale quench model of HTS coil is developed, which can be used to estimate minimum quench energy and normal zone propagation velocity inside the coil. In addition, we study the influence of inhomogeneity of HTS bulk during pulse magnetization. We demonstrate how the inhomogeneous distribution of critical current inside the bulk results in varying degrees of heat dissipation and uniformity of final trapped field. The temperature-dependent model is proven to be a powerful tool to study the thermally coupled electromagnetic phenomena of HTS.

  3. Applicability of effective medium description to photonic crystals in higher bands: Theory and numerical analysis

    NASA Astrophysics Data System (ADS)

    Markel, Vadim A.; Tsukerman, Igor

    2016-06-01

    We consider conditions under which photonic crystals (PCs) can be homogenized in the higher photonic bands and, in particular, near the Γ point. By homogenization we mean introducing some effective local parameters ɛeff and μeff that describe reflection, refraction, and propagation of electromagnetic waves in the PC adequately. The parameters ɛeff and μeff can be associated with a hypothetical homogeneous effective medium. In particular, if the PC is homogenizable, the dispersion relations and isofrequency lines in the effective medium and in the PC should coincide to some level of approximation. We can view this requirement as a necessary condition of homogenizability. In the vicinity of a Γ point, real isofrequency lines of two-dimensional PCs can be close to mathematical circles, just like in the case of isotropic homogeneous materials. Thus, one may be tempted to conclude that introduction of an effective medium is possible and, at least, the necessary condition of homogenizability holds in this case. We, however, show that this conclusion is incorrect: complex dispersion points must be included into consideration even in the case of strictly nonabsorbing materials. By analyzing the complex dispersion relations and the corresponding isofrequency lines, we have found that two-dimensional PCs with C4 and C6 symmetries are not homogenizable in the higher photonic bands. We also draw a distinction between spurious Γ -point frequencies that are due to Brillouin-zone folding of Bloch bands and "true" Γ -point frequencies that are due to multiple scattering. Understanding of the physically different phenomena that lead to the appearance of spurious and "true" Γ -point frequencies is important for the theory of homogenization.

  4. Sequential Application of Steady and Pulsatile Medium Perfusion Enhanced the Formation of Engineered Bone

    PubMed Central

    Correia, Cristina; Bhumiratana, Sarindr; Sousa, Rui A.; Reis, Rui L.

    2013-01-01

    In native bone, cells experience fluctuating shear forces that are induced by pulsatile interstitial flow associated with habitual loading. We hypothesized that the formation of engineered bone can be augmented by replicating such physiologic stimuli to osteogenic cells cultured in porous scaffolds using bioreactors with medium perfusion. To test this hypothesis, we investigated the effect of fluid flow regime on in vitro bone-like tissue development by human adipose stem cells (hASC) cultivated on porous three-dimensional silk fibroin scaffolds. To this end, we varied the sequential relative durations of steady flow (SF) and pulsatile flow (PF) of culture medium applied over a period of 5 weeks, and evaluated their effect on early stages of bone formation. Porous silk fibroin scaffolds (400–600 μm pore size) were seeded with hASC (30×106 cells/mL) and cultured in osteogenic medium under four distinct fluid flow regimes: (1) PF for 5 weeks; (2) SF for 1 week, PF for 4 weeks; (3) SF for 2 weeks, PF for 3 weeks; (4) SF for 5 weeks. The PF was applied in 12 h intervals, with the interstitial velocity fluctuating between 400 and 1200 μm/s at a 0.5 Hz frequency for 2 h, followed by 10 h of SF. In all groups, SF was applied at 400 μm/s. The best osteogenic outcomes were achieved for the sequence of 2 weeks of SF and 3 weeks of PF, as evidenced by gene expression (including the PGE2 mechanotransduction marker), construct compositions, histomorphologies, and biomechanical properties. We thus propose that osteogenesis in hASC and the subsequent early stage bone development involve a mechanism, which detects and responds to the level and duration of hydrodynamic shear forces. PMID:23259605

  5. Ultra-High Temperature Materials Characterization for Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Rogers, Jan; Hyers, Robert

    2007-01-01

    Propulsion system efficiency increases as operating temperatures are increased. Some very high-temperature materials are being developed, including refractory metal alloys, carbides, borides, and silicides. System design requires data for materials properties at operating temperatures. Materials property data are not available for many materials of interest at the desired operating temperatures (up to approx. 3000 K). The objective of this work is to provide important physical property data at ultra-high temperatures. The MSFC Electrostatic levitation (ESL) facility can provide measurements of thermophysical properties which include: creep strength, density and thermal expansion for materials being developed for propulsion applications. The ESL facility uses electrostatic fields to position samples between electrodes during processing and characterization studies. Because the samples float between the electrodes during studies, they are free from any contact with a container or test apparatus. This provides a high purity environment for the study of high-temperature, reactive materials. ESL can be used to process a wide variety of materials including metals, alloys, ceramics, glasses and semiconductors. The MSFC ESL has provided non-contact measurements of properties of materials up to 3400 C. Density and thermal expansion are measured by analyzing digital images of the sample at different temperatures. Our novel, non-contact method for measuring creep uses rapid rotation to deform the sample. Digital images of the deformed samples are analyzed to obtain the creep properties, which match those obtained using ASTM Standard E-139 for Nb at 1985 C. Data from selected ESL-based characterization studies will be presented. The ESL technique could support numerous propulsion technologies by advancing the knowledge base and the technology readiness level for ultra-high temperature materials. Applications include non-eroding nozzle materials and lightweight, high-temperature

  6. Optical fiber temperature sensors: applications in heat treatments for foods

    NASA Astrophysics Data System (ADS)

    Sosa-Morales, María Elena; Rojas-Laguna, Roberto; López-Malo, Aurelio

    2010-10-01

    Heat treatments are important methods to provide safe foods. Conventional heat treatments involve the application of steam and recently microwave treatments have been studied and applied as they are considered as fast, clean and efficient. Optical fiber sensing is an excellent tool to measure the temperature during microwave treatments. This paper shows the application of optical fiber temperature sensing during the heat treatment of different foods such as vegetables (jalapeño pepper and cilantro), cheese and ostrich meat. Reaching the target temperature, important bacteria were inactivated: Salmonella, Listeria and Escherichia coli. Thus, the use of optical fiber sensors has resulted be a useful way to develop protocols to inactivate microorganisms and to propose new methods for food processing.

  7. NEW OPTICAL SENSOR SUITE FOR ULTRAHIGH TEMPERATURE FOSSIL FUEL APPLICATIONS

    SciTech Connect

    Russell G. May; Tony Peng; Tom Flynn

    2004-04-01

    Accomplishments during the first six months of a program to develop and demonstrate technology for the instrumentation of advanced powerplants are described. Engineers from Prime Research, LC and Babcock and Wilcox Research Center collaborated to generate a list of potential applications for robust photonic sensors in existing and future boiler plants. From that list, three applications were identified as primary candidates for initial development and demonstration of high-temperature sensors in an ultrasupercritical power plant. In addition, progress was made in the development of materials and methods to apply high-temperature optical claddings to sapphire fibers, in order to improve their optical waveguiding properties so that they can be used in the design and fabrication of high-temperature sensors. Through refinements in the processing steps, the quality of the interface between core and cladding of the fibers was improved, which is expected to reduce scattering and attenuation in the fibers.

  8. Coal liquefaction in an inorganic-organic medium. [DOE patent application

    DOEpatents

    Vermeulen, T.; Grens, E.A. II; Holten, R.R.

    Improved process for liquefaction of coal by contacting pulverized coal in an inorganic-organic medium solvent system containing a ZnCl/sub 2/ catalyst, a polar solvent with the structure RX where X is one of the elements O, N, S, or P, and R is hydrogen or a lower hydrocarbon radical; the solvent system can contain a hydrogen donor solvent (and must when RX is water) which is immiscible in the ZnCl/sub 2/ and is a hydroaromatic hydrocarbon selected from tetralin, dihydrophenanthrene, dihydroanthracene or a hydrogenated coal derived hydroaromatic hydrocarbon distillate fraction.

  9. InfraRed Standards Used for Spectrophotometric Calibration - Application to the Medium Resolution Spectrometer of {MIRI}

    NASA Astrophysics Data System (ADS)

    Decin, L.; Bauwens, E.; Blommaert, J. A. D. L.

    2007-04-01

    One of the main ingredients in establishing the relation between input signal and output flux from a spectrometer, is the accurate determination of the {spectrophotometric calibration}. In case of spectrometers onboard satellites, the accuracy of this part of the calibration pedigree is ultimately linked to the reliability of the candidate calibrators as being fiducial. In this contribution, we deal with the spectrophotometric calibration of {infrared} spectrometers in the 2-200 μm wavelength range. We outline a general selection procedure to arrive at a set of fiducial IR calibrators, and apply the method to the Medium Resolution Spectrometer of MIRI which will be onboard the James Webb Space Telescope.

  10. Application of short-coherence lensless Fourier-transform digital holography in imaging through diffusive medium

    NASA Astrophysics Data System (ADS)

    Zhang, Yizhuo; Situ, Guohai; Pedrini, Giancarlo; Wang, Dayong; Javidi, Bahram; Osten, Wolfgang

    2013-01-01

    We propose a short-coherence lensless Fourier-transform digital holography for imaging through scattering media. The technique utilizes a low-power cw diode laser with short temporal coherence and enables the selection of the early-arriving photons through a diffusive medium by interfering with a spherical reference beam from the same source. An averaging technique is introduced to extract the weak signal from strong background noise. The proposed technique is verified using both theoretical analysis and experimental demonstration by imaging an object through a 3-mm-thick chicken breast tissue.

  11. Application of oil-swollen surfactant gels as a growth medium for metal nanoparticle synthesis, and as an exfoliation medium for preparation of graphene.

    PubMed

    Upadhyay, Ravi Kant; Waghmare, Prashant R; Roy, Susanta Sinha

    2016-07-15

    Gel is an intermediate phase of solid and liquid, which exhibits properties of both, and this unique feature of gel has made it an excellent choice as a reaction medium for the nanomaterials synthesis. Herein, we report use of oil swollen surfactant gels as reaction medium and exfoliation medium, for the synthesis of metals (Au, Ag) nanoparticles and graphene, respectively. Confined growth of metals (Au and Ag) nanoparticles, has been achieved by exploring tween 80 based surfactant gel as a reaction medium. Au NPs prepared within tween 80 gel were found to be spherical with size ∼5nm, arranged in template micelles. Heating triggered the growth of Au nanoparticles and particles of various shapes including triangles, rods and pentagonal, were produced. Au and Ag containing tween 80 gels were found to be promising as catalysts for the nitrophenol reduction. Apart from separate synthesis of Au and Ag nanoparticles, bimetallic (Au-Ag) nanoparticles have also been synthesized by taking advantage of selective reducing property of tween 80. First time CTAB gel has been utilized as an exfoliation medium for the quick exfoliation of graphite into graphene sheets, eliminating the necessity of any external driving force such as sonication or heating, to reinforce exfoliation. PMID:27093455

  12. Electrically Joining Mixed Conducting Oxides for High Temperature Applications

    SciTech Connect

    Weil, K. Scott; Hardy, John S.

    2003-01-06

    Mixed conducting oxides such as lanthanum strontium cobalt ferrite are currently being investigated for potential use as electrochemically active electrodes and catalytic membranes in a number of high temperature devices, including oxygen generators and solid oxide fuel cells (SOFC). However to take full advantage of the unique properties of these materials, reliable joining techniques need to be developed. What complicates joining in these applications is the requirement that the ceramic-to-metal junction be electrically conductive, so that current can either be drawn from the mixed conducting oxide, in the case of SOFC applications, or be carried to the oxide to initate ionic conduction, as required for oxygen separation and electrocatalysis. This paper outlines a new technique that is being developed to electrically join an oxide conductor to a metal current collector for high temperature electrochemical application.

  13. Calculated sputtering and atomic displacement cross-sections for applications to medium voltage analytical electron microscopy

    SciTech Connect

    Bradley, C.R.; Zaluzec, N.J.

    1987-08-01

    The development of medium voltage electron microscopes having high brightness electron sources and ultra-high vacuum environments has been anticipated by the microscopy community now for several years. The advantages of such a configuration have been discussed to great lengths, while the potential disadvantages have for the most part been neglected. The most detrimental of these relative to microcharacterization are the effects of electron sputtering and atomic displacement to the local specimen composition. These effects have in the past been considered mainly in the high voltage electron microscope regime and generally were ignored in lower voltage instruments. Recent experimental measurements have shown that the effects of electron sputtering as well as radiation induced segregation can be observed in conventional transmission electron microscopes. It is, therefore, important to determine at what point the effects will begin to manifest themselves in the new generation of medium voltage analytical electron microscopes. In this manuscript we present new calculations which allow the individual experimentalist to determine the potential threshold levels for a particular elemental system and thus avoid the dangers of introducing artifacts during microanalysis. 12 refs., 3 figs.

  14. Surface response of a viscoelastic medium to subsurface acoustic sources with application to medical diagnosis

    NASA Astrophysics Data System (ADS)

    Royston, Thomas J.; Yazicioglu, Yigit; Loth, Francis

    2003-02-01

    The response at the surface of an isotropic viscoelastic medium to buried fundamental acoustic sources is studied theoretically, computationally and experimentally. Finite and infinitesimal monopole and dipole sources within the low audible frequency range (40-400 Hz) are considered. Analytical and numerical integral solutions that account for compression, shear and surface wave response to the buried sources are formulated and compared with numerical finite element simulations and experimental studies on finite dimension phantom models. It is found that at low audible frequencies, compression and shear wave propagation from point sources can both be significant, with shear wave effects becoming less significant as frequency increases. Additionally, it is shown that simple closed-form analytical approximations based on an infinite medium model agree well with numerically obtained ``exact'' half-space solutions for the frequency range and material of interest in this study. The focus here is on developing a better understanding of how biological soft tissue affects the transmission of vibro-acoustic energy from biological acoustic sources below the skin surface, whose typical spectral content is in the low audible frequency range. Examples include sound radiated from pulmonary, gastro-intestinal and cardiovascular system functions, such as breath sounds, bowel sounds and vascular bruits, respectively.

  15. Application of an effective medium theory for modeling ultrasound wave propagation in healing long bones.

    PubMed

    Potsika, Vassiliki T; Grivas, Konstantinos N; Protopappas, Vasilios C; Vavva, Maria G; Raum, Kay; Rohrbach, Daniel; Polyzos, Demosthenes; Fotiadis, Dimitrios I

    2014-07-01

    Quantitative ultrasound has recently drawn significant interest in the monitoring of the bone healing process. Several research groups have studied ultrasound propagation in healing bones numerically, assuming callus to be a homogeneous and isotropic medium, thus neglecting the multiple scattering phenomena that occur due to the porous nature of callus. In this study, we model ultrasound wave propagation in healing long bones using an iterative effective medium approximation (IEMA), which has been shown to be significantly accurate for highly concentrated elastic mixtures. First, the effectiveness of IEMA in bone characterization is examined: (a) by comparing the theoretical phase velocities with experimental measurements in cancellous bone mimicking phantoms, and (b) by simulating wave propagation in complex healing bone geometries by using IEMA. The original material properties of cortical bone and callus were derived using serial scanning acoustic microscopy (SAM) images from previous animal studies. Guided wave analysis is performed for different healing stages and the results clearly indicate that IEMA predictions could provide supplementary information for bone assessment during the healing process. This methodology could potentially be applied in numerical studies dealing with wave propagation in composite media such as healing or osteoporotic bones in order to reduce the simulation time and simplify the study of complicated geometries with a significant porous nature. PMID:24091149

  16. NiAl alloys for high-temperature structural applications

    NASA Astrophysics Data System (ADS)

    Darolia, Ram

    1991-03-01

    If their properties can be improved, nickel aluminide alloys offer significant payoffs in gas turbine engine applications. For these materials, excellent progress has been made toward understanding their mechanical behavior as well as improving their low-temperature ductility and high-temperature strength. For example, recent work shows that room-temperature ductility can be improved dramatically by microalloying with iron, gallium or molybdenum. The next challenge is to develop an alloy which has the required balance of ductility, toughness and strength. Development of design and test methodologies for components made out of low-ductility, anisotropic materials will also be required. While significant challenges remain, the continuing developments suggest that the prognosis for using NiAl alloys as high-temperature structural materials is good.

  17. Evaluation of Capacitors at Cryogenic Temperatures for Space Applications

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Hammoud, Ahmad; Gerber, Scott S.

    1998-01-01

    Advanced electronic systems designed for use in planetary exploration missions must operate efficiently and reliably under the extreme cold temperatures of deep space environment. In addition, spacecraft power electronics capable of cold temperature operation will greatly simplify the thermal management system by eliminating the need for heating units and associated equipment and thereby reduce the size and weight of the overall power system. In this study, film, mica, solid tantalum and electric double layer capacitors were evaluated as a function of temperature from room to liquid nitrogen in terms of their dielectric properties. These properties included capacitance stability and dielectric loss in the frequency range of 50 Hz to 100 kHz. DC leakage current measurements were also performed on the capacitors. The results obtained are discussed and conclusions are made concerning the suitability of the capacitors investigated for low temperature applications.

  18. Direct transfer of solar radiation to high temperature applications

    NASA Astrophysics Data System (ADS)

    Rahou, Maryam; Andrews, John; Rosengarten, Gary

    2013-12-01

    This paper reviews the different methods of directly transferring solar radiation from concentrated solar collectors to medium to high temperature thermal absorbers, at temperatures ranging from 100 to 400°. These methods are divided into four main categories associated with the radiation transfer medium: optical fibres, photonic crystal fibres, metal waveguides and light guides. The reviewed methods are novel compared to most rooftop solar concentrators that have a receiver and a thermal storage unit coupled by heat transfer fluids. Bundled optical fibres have the capability of transferring concentrated solar energy across the full wavelength spectrum with the maximum optical efficiency. In this study two different types of optical bundle, including hard polymer cladding silica (HPCS) and polymer clad silica (PCS) fibres are introduced which offer a broad spectrum transmission range from 300 to 1700 nm, low levels of losses through attenuation and the best resistance to heating. These fibres are able to transmit about 94% of the solar radiation over a distance of 10 m. The main parameters that determine the overall efficiency of the system are the concentration ratio, the acceptance angle of the fibres, and the matching of the diameter of the focus spot of the concentrator and the internal diameter of the fibre. In order to maximize the coupling efficiency of the system, higher levels of concentration are required which can be achieved through lenses or other non-imaging concentrators. However, these additional components add to the cost and complexity of the system. To avoid this problem we use tapered bundles of optical fibres that enhance the coupling efficiency by increasing the acceptance angle and consequently the coupling efficiency of the system.

  19. ICDC interstitial ultrasound applicators for high-temperature thermal therapy

    NASA Astrophysics Data System (ADS)

    Tyreus, Per Daniel; Diederich, Chris J.; Nau, William H.

    2001-06-01

    Theoretical and experimental approaches were used to evaluate Internally-Cooled Direct-Coupled (ICDC) ultrasound applicators for treating disease in the prostate and liver. 2-D and 3-D transient biothermal models, which account for dynamic tissue changes, were used to calculate temperature distributions and zones of coagulation. Experimental evaluations and verification of these models were performed using in vitro tissue and in vivo porcine and canine models. Devices of 2.2 mm outer diameter were evaluated under varied applied power schemes and cooling levels. Both duty cycle power application and PI-controlled power application were found to improve applicator performance by increasing radial depths of lesions with lower maximum temperature. ICDC applicators were found to be able to create 3-5 cm diameter lesions in liver and muscle under 15 minute treatment times using the optimal designs and power application schemes found in this study. From these initial feasibility studies it has been demonstrated that ICDC devices have potential for treating cancerous tumors in prostate, liver and possibly breast.

  20. Applications of Thin Film Thermocouples for Surface Temperature Measurement

    NASA Technical Reports Server (NTRS)

    Martin, Lisa C.; Holanda, Raymond

    1994-01-01

    Thin film thermocouples provide a minimally intrusive means of measuring surface temperature in hostile, high temperature environments. Unlike wire thermocouples, thin films do not necessitate any machining of the surface, therefore leaving intact its structural integrity. Thin films are many orders of magnitude thinner than wire, resulting in less disruption to the gas flow and thermal patterns that exist in the operating environment. Thin film thermocouples have been developed for surface temperature measurement on a variety of engine materials. The sensors are fabricated in the NASA Lewis Research Center's Thin Film Sensor Lab, which is a class 1000 clean room. The thermocouples are platinum-13 percent rhodium versus platinum and are fabricated by the sputtering process. Thin film-to-leadwire connections are made using the parallel-gap welding process. Thermocouples have been developed for use on superalloys, ceramics and ceramic composites, and intermetallics. Some applications of thin film thermocouples are: temperature measurement of space shuttle main engine turbine blade materials, temperature measurement in gas turbine engine testing of advanced materials, and temperature and heat flux measurements in a diesel engine. Fabrication of thin film thermocouples is described. Sensor durability, drift rate, and maximum temperature capabilities are addressed.

  1. [Application of health questionnaires for health management in small- and medium-sized enterprises].

    PubMed

    Kishida, K; Saito, M; Hasegawa, T; Aoki, S; Suzuki, S

    1986-01-01

    Two kinds of health questionnaires, the Todai Health Index (THI) and Cumulative Fatigue Index (CFI), were applied as a screening device for health management of workers belonging to small-medium sized enterprises. A total of 495 workers composed of 452 male workers of a glass-bottle manufacturing factory and 43 male workers of a soft-drink bottling factory were the subjects of the present study. It was found that the two kinds of health questionnaires were different from each other and have their own characteristics. Twelve scales of THI were grouped into two, the first consisting of ten scales (SUSY, RESP, EYSK, MOUT, DIGE, IMPU, MENT, DEPR, NERV, and LIFE) and the second consisting of two scales (AGGR and LISC). Nine categories of CFI were grouped into one by using principal factor analysis. It was confirmed that the twelve scale scores of THI obtained at small-medium sized factories differed from those scale scores of a reference group investigated at a large-sized enterprise. It is on the basis of the scales of aggressiveness and lies and also of the scale of mental unstability which characterizes workers, locality, job (clerical or field work), and size of industry (large or small sized) that the difference could be evaluated. Urban life characterized by a life style of staying up late at night and waking up late in the morning has been reflected on the scale of life irregularity. Irregularity of life induced by transformation of working schedule, such as two or three shifts of work and overtime, was also reflected on this scale. Two scales of THI test, i.e., many subjective symptoms and digestive organ complaints, seemed to be the representative scales indicating a close relation between work load and health level. The discriminant score for diagnosis of psychosomatic diseases is considered to be one of the most useful assessments of the individual's health condition. As mentioned above, THI is recommended as a convenient assessment method for health

  2. SiC Die Attach for High-Temperature Applications

    NASA Astrophysics Data System (ADS)

    Drevin-Bazin, A.; Lacroix, F.; Barbot, J.-F.

    2013-11-01

    Eutectic solders AuIn19 and AuGe12 and nanosilver paste were investigated for SiC die attach in high-temperature (300°C) applications. The soldering or sintering conditions were optimized through die shear tests performed at room temperature. In particular, application of static pressure (3.5 MPa) during sintering resulted in greatly improved mechanical behavior of the nanosilver-based joint. Microstructural study of the eutectic solders showed formation of Au-rich grains in AuGe die attach and significant diffusion of Au and In through the Ni layer in AuIn19 die attach, which could lead to formation of intermetallic compounds. Die shear tests versus temperature showed that the behaviors of the studied die attaches are different; nevertheless they present suitable shear strengths required for high-temperature applications. The mechanical behavior of joints under various levels of thermal and mechanical stress was also studied. Creep experiments were carried out on the eutectic solders to describe the thermomechanical behavior of the complete module; only one creep mechanism was observed in the working range.

  3. High-temperature electronics applications in space exploration

    NASA Technical Reports Server (NTRS)

    Jurgens, R. F.

    1982-01-01

    One of the most exciting applications of high-temperature electronics is related to the exploration of the planet Venus. On this planet the atmospheric temperatures range from about 170 K at elevations of 100 km to a searing 730 K near the surface. Mechanisms for exploring the atmosphere might include balloons, airplanes, surface landers, and surface-launched probes. Balloons, for example, could fly in the region from 20 (320 C at 22 bars) to 60 km (-20 C at 0.2 bar). Suitable balloon fabrics presently exclude excursions to lower altitudes; however, adequate electronic systems could survive to 325 C. Small airplanes would require more sophisticated electronics for guidance and control. Long life surface landers would most likely be developed first, as these could be used to measure long-term variations in weather. Ranging transponders would be important for ephemeris development, measurement of spin state, and studies of general relativity. Surface temperatures of 460 C and pressures of 90 bars present a challenge to the developers of such instruments. Other space applications for high-temperature electronics include transponders for the surface of Mercury, near solar drag-free orbiters, and deep atmospheric penetrators for Jupiter and Saturn. Each of these has its own particular problems with respect to instrumentation adequate to meet the desired scientific goals. This paper is primarily concerned with defining possible mission applications, the required electronic systems, and the approaches that are currently being studied for their development.

  4. Fiber optic strain and temperature sensor for power plant applications

    NASA Astrophysics Data System (ADS)

    Narendran, Nadarajah; Weiss, Joseph M.

    1996-01-01

    The applicability of fiber-optic strain and temperature sensors to monitor power plant structures was evaluated on a super-heated steam pipe operating at 1000 degree(s)F at the Tennessee Valley Authority power plant in Kingston, Tennessee. The potential applications of these fiber-optic sensors include health monitoring of high-temperature structures such as boilers, tube headers, and steam pipes, as well as many other power plant structures exposed to less severe environments. The sensor selected for this application is based on a white-light interferometric technique. The key features of this sensor include its ability for absolute measurements that are not affected by light loss along the fiber cable due to, for example, microbending effects and coupler loss, its compatibility with off-the-shelf fiber-optic components, and its low cost. The glass fiber-optic strain sensors were packaged in a rugged metal housing and were spot welded to the high-temperature steam pipe. Another set of gages was placed inside a thermowell for steam temperature measurement. Data collected during a routine start-up is very encouraging and the details are presented in this manuscript.

  5. Long term application of bus monitoring system to short and medium span bridges and damage detection

    NASA Astrophysics Data System (ADS)

    Miyamoto, Ayaho; Lúcio, Válter J. G.; Emoto, Hisao; Tanaka, Hideaki

    2015-07-01

    In this study, as one solution to the problem for condition assessment of existing short and medium span reinforced/prestressed concrete bridges, a new monitoring method using a public bus as part of a public transit system (bus monitoring system) is proposed, along with safety indices, namely, characteristic deflection, which is relatively free from the influence of dynamic disturbances due to such factors as the roughness of the road surface, and a structural anomaly parameter. A basic study was conducted by using the results of technical verification experiments and numerical analysis simulation. This paper describes the details of not only how to assess the bridge condition by public bus vibration measured in operating on Ube City bus network as a specific example for verify the system but also what kind of consideration we need to apply the system to existing bridges in overseas country.

  6. Application of MSOR iteration with Newton scheme for solutions of 1D nonlinear porous medium equations

    NASA Astrophysics Data System (ADS)

    Chew, J. V. L.; Sulaiman, J.

    2016-06-01

    This paper considers Newton-MSOR iterative method for solving 1D nonlinear porous medium equation (PME). The basic concept of proposed iterative method is derived from a combination of one step nonlinear iterative method which known as Newton method with Modified Successive Over Relaxation (MSOR) method. The reliability of Newton-MSOR to obtain approximate solution for several PME problems is compared with Newton-Gauss-Seidel (Newton-GS) and Newton-Successive Over Relaxation (Newton-SOR). In this paper, the formulation and implementation of these three iterative methods have also been presented. From four examples of PME problems, numerical results showed that Newton-MSOR method requires lesser number of iterations and computational time as compared with Newton-GS and Newton-SOR methods.

  7. Application of UV based advanced oxidation to treat sulfolane in an aqueous medium.

    PubMed

    Yu, Linlong; Mehrabani-Zeinabad, Mitra; Achari, Gopal; Langford, Cooper H

    2016-10-01

    Several oxidative methods were studied to degrade sulfolane in an aqueous medium. These include UVA and UVC irradiation with suitable photoactive oxidants, including ozone, H2O2, and TiO2 based photocatalysis and their combinations. Since sulfolane lacks absorption bands in the UV range beyond 200 nm, initiation of reactions depends on the spectra and photochemistry of the oxidants. Among all the advanced oxidation processes investigated, combinations of (a) UVC with H2O2 and O3 (b) UVC with H2O2 and (c) UVC with O3 led to the highest rate of sulfolane loss in synthetic water samples. Experiments on sulfolane contaminated groundwater samples also indicated that these three combinations can efficiently degrade sulfolane. Furthermore, a synergistic effect was observed in the combination of H2O2 and O3 photolysis. PMID:27372265

  8. Analysis of Low Temperature Organic Rankine Cycles for Solar Applications

    NASA Astrophysics Data System (ADS)

    Li, Yunfei

    The present work focuses on Organic Rankine Cycle (ORC) systems and their application to low temperature waste heat recovery, combined heat and power as well as off-grid solar power generation applications. As CO_2 issues come to the fore front and fossil fuels become more expensive, interest in low grade heat recovery has grown dramatically in the past few years. Solar energy, as a clean, renewable, pollution-free and sustainable energy has great potential for the use of ORC systems. Several ORC solutions have been proposed to generate electricity from low temperature sources. The ORC systems discussed here can be applied to fields such as solar thermal, biological waste heat, engine exhaust gases, small-scale cogeneration, domestic boilers, etc. The current work presents a thermodynamic and economic analysis for the use of ORC systems to convert solar energy or low exergy energy to generate electrical power. The organic working fluids investigated here were selected to investigate the effect of the fluid saturation temperature on the performance of ORCs. The working fluids under investigation are R113, R245fa, R123, with boiling points between 40°C and 200°C at pressures from 10 kPa to 10 MPa. Ambient temperature air at 20oC to 30oC is utilized as cooling resource, and allowing for a temperature difference 10°C for effective heat transfer. Consequently, the working fluids are condensed at 40°C. A combined first- and second-law analysis is performed by varying some system independent parameters at various reference temperatures. The present work shows that ORC systems can be viable and economical for the applications such as waste heat use and off-grid power generation even though they are likely to be more expensive than grid power.

  9. Lauric acid-rich medium-chain triglycerides can substitute for other oils in cooking applications and may have limited pathogenicity

    PubMed Central

    McCarty, Mark F; DiNicolantonio, James J

    2016-01-01

    Recently, medium-chain triglycerides (MCTs) containing a large fraction of lauric acid (LA) (C12)—about 30%—have been introduced commercially for use in salad oils and in cooking applications. As compared to the long-chain fatty acids found in other cooking oils, the medium-chain fats in MCTs are far less likely to be stored in adipose tissue, do not give rise to ‘ectopic fat’ metabolites that promote insulin resistance and inflammation, and may be less likely to activate macrophages. When ingested, medium-chain fatty acids are rapidly oxidised in hepatic mitochondria; the resulting glut of acetyl-coenzyme A drives ketone body production and also provokes a thermogenic response. Hence, studies in animals and humans indicate that MCT ingestion is less obesogenic than comparable intakes of longer chain oils. Although LA tends to raise serum cholesterol, it has a more substantial impact on high density lipoprotein (HDL) than low density lipoprotein (LDL) in this regard, such that the ratio of total cholesterol to HDL cholesterol decreases. LA constitutes about 50% of the fatty acid content of coconut oil; south Asian and Oceanic societies which use coconut oil as their primary source of dietary fat tend to be at low cardiovascular risk. Since ketone bodies can exert neuroprotective effects, the moderate ketosis induced by regular MCT ingestion may have neuroprotective potential. As compared to traditional MCTs featuring C6–C10, laurate-rich MCTs are more feasible for use in moderate-temperature frying and tend to produce a lower but more sustained pattern of blood ketone elevation owing to the more gradual hepatic oxidation of ingested laurate. PMID:27547436

  10. Lauric acid-rich medium-chain triglycerides can substitute for other oils in cooking applications and may have limited pathogenicity.

    PubMed

    McCarty, Mark F; DiNicolantonio, James J

    2016-01-01

    Recently, medium-chain triglycerides (MCTs) containing a large fraction of lauric acid (LA) (C12)-about 30%-have been introduced commercially for use in salad oils and in cooking applications. As compared to the long-chain fatty acids found in other cooking oils, the medium-chain fats in MCTs are far less likely to be stored in adipose tissue, do not give rise to 'ectopic fat' metabolites that promote insulin resistance and inflammation, and may be less likely to activate macrophages. When ingested, medium-chain fatty acids are rapidly oxidised in hepatic mitochondria; the resulting glut of acetyl-coenzyme A drives ketone body production and also provokes a thermogenic response. Hence, studies in animals and humans indicate that MCT ingestion is less obesogenic than comparable intakes of longer chain oils. Although LA tends to raise serum cholesterol, it has a more substantial impact on high density lipoprotein (HDL) than low density lipoprotein (LDL) in this regard, such that the ratio of total cholesterol to HDL cholesterol decreases. LA constitutes about 50% of the fatty acid content of coconut oil; south Asian and Oceanic societies which use coconut oil as their primary source of dietary fat tend to be at low cardiovascular risk. Since ketone bodies can exert neuroprotective effects, the moderate ketosis induced by regular MCT ingestion may have neuroprotective potential. As compared to traditional MCTs featuring C6-C10, laurate-rich MCTs are more feasible for use in moderate-temperature frying and tend to produce a lower but more sustained pattern of blood ketone elevation owing to the more gradual hepatic oxidation of ingested laurate. PMID:27547436

  11. NEW OPTICAL SENSOR SUITE FOR ULTRAHIGH TEMPERATURE FOSSIL FUEL APPLICATIONS

    SciTech Connect

    Russell G. May; Tony Peng; Tom Flynn

    2004-12-01

    Accomplishments during the Phase I of a program to develop and demonstrate technology for the instrumentation of advanced powerplants are described. Engineers from Prime Research, LC and Babcock and Wilcox Research Center collaborated to generate a list of potential applications for robust photonic sensors in existing and future boiler plants. From that list, three applications were identified as primary candidates for initial development and demonstration of high-temperature sensors in an ultrasupercritical power plant. A matrix of potential fiber optic sensor approaches was derived, and a data set of specifications for high-temperature optical fiber was produced. Several fiber optic sensor configurations, including interferometric (extrinsic and intrinsic Fabry-Perot interferometer), gratings (fiber Bragg gratings and long period gratings), and microbend sensors, were evaluated in the laboratory. In addition, progress was made in the development of materials and methods to apply high-temperature optical claddings to sapphire fibers, in order to improve their optical waveguiding properties so that they can be used in the design and fabrication of high-temperature sensors. Through refinements in the processing steps, the quality of the interface between core and cladding of the fibers was improved, which is expected to reduce scattering and attenuation in the fibers. Numerical aperture measurements of both clad and unclad sapphire fibers were obtained and used to estimate the reduction in mode volume afforded by the cladding. High-temperature sensors based on sapphire fibers were also investigated. The fabrication of an intrinsic Fabry-Perot cavity within sapphire fibers was attempted by the bulk diffusion of magnesium oxide into short localized segments of longer sapphire fibers. Fourier analysis of the fringes that resulted when the treated fiber was interrogated by a swept laser spectrometer suggested that an intrinsic cavity had been formed in the fiber. Also

  12. Non-graphite crucible for high temperature applications

    DOEpatents

    Holcombe, C.E.; Pfeiler, W.A.

    1996-01-09

    A multi-piece crucible for high temperature applications comprises a tubular side wall member having a lip on the inside surface and a bottom member or members forming a container for containing a melt of a material during a high temperature melt-casting operations. The multi-piece design prevents cracking of the crucible or leakage of the melt from the crucible during the melt-casting operation. The lip of the tubular member supports the bottom member. The contacting surfaces where the lip of the tubular side wall member contacts the bottom member of the multi-piece crucible contains a ceramic sealing material. The ceramic sealing material forms a seal sufficient to prevent the melt of the material from leaking out of the multi-piece crucible during the melt-casting process. The multi-piece crucible is made of a material which is chemically inert to the melt and has structural integrity at the melting point temperature of the melt, or of a material coated with such a material. The multi-piece crucible is contained in a thermal can assembly of a high temperature induction furnace during a high temperature melt-casting operation. One embodiment of the multi-piece crucible comprises a tubular member having a vertical slot filled with a ceramic sealing material to provide expansion of the tubular member without cracking during the high temperature melt-casting operation. 9 figs.

  13. Non-graphite crucible for high temperature applications

    DOEpatents

    Holcombe, Cressie E.; Pfeiler, William A.

    1996-01-01

    A multi-piece crucible for high temperature applications comprises a tubular side wall member having a lip on the inside surface and a bottom member or members forming a container for containing a melt of a material during a high temperature melt-casting operations. The multi-piece design prevents cracking of the crucible or leakage of the melt from the crucible during the melt-casting operation. The lip of the tubular member supports the bottom member. The contacting surfaces where the lip of the tubular side wall member contacts the bottom member of the multi-piece crucible contains a ceramic sealing material. The ceramic sealing material forms a seal sufficient to prevent the melt of the material from leaking out of the multi-piece crucible during the melt-casting process. The multi-piece crucible is made of a material which is chemically inert to the melt and has structural integrity at the melting point temperature of the melt, or of a material coated with such a material. The multi-piece crucible is contained in a thermal can assembly of a high temperature induction furnace during a high temperature melt-casting operation. One embodiment of the multi-piece crucible comprises a tubular member having a vertical slot filled with a ceramic sealing material to provide expansion of the tubular member without cracking during the high temperature melt-casting operation.

  14. High temperature braided rope seals for static sealing applications

    NASA Technical Reports Server (NTRS)

    Adams, Michael L.; Olsen, Andrew; Darolia, Ram; Steinetz, Bruce M.; Bartolotta, Paul A.

    1996-01-01

    Achieving efficiency and performance goals of advanced aircraft and industrial systems are leading designers to implement high temperature materials such as ceramics and intermetallics. Generally these advanced materials are applied selectively in the highest temperature sections of the engine system including the combustor and high pressure turbine, amongst others. Thermal strains that result in attaching the low expansion-rate components to high expansion rate superalloy structures can cause significant life reduction in the components. Seals are being designed to both seal and to serve as compliant mounts allowing for relative thermal growths between high temperature but brittle primary structures and the surrounding support structures. Designers require high temperature, low-leakage, compliant seals to mitigate thermal stresses and control parasitic and cooling airflow between structures. NASA is developing high temperature braided rope seals in a variety of configurations to help solve these problems. This paper will describe the types of seals being developed, describe unique test techniques used to assess seal performance, and present leakage flow data under representative pressure, temperature and scrubbing conditions. Feasibility of the braided rope seals for both an industrial tube seal and a turbine vane seal application is also demonstrated.

  15. Industrial applications of low-temperature plasma physics

    SciTech Connect

    Chen, F.F.

    1995-06-01

    The application of plasma physics to the manufacturing and processing of materials may be the new frontier of our discipline. Already partially ionized discharges are used in industry, and the performance of plasmas has a large commercial and technological impact. However, the science of low-temperature plasmas is not as well developed as that of high-temperature, collisionless plasmas. In this paper several major areas of application are described and examples of forefront problems in each are given. The underlying thesis is that gas discharges have evolved beyond a black art, and that intellectually challenging problems with elegant solutions can be found. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  16. A facility for precise temperature control applications in microgravity

    NASA Astrophysics Data System (ADS)

    Glicksman, M. E.; Lograsso, T. A.; Tirmizi, S. H.; Hahn, R. C.; Winsa, E.

    The general design, main components, and operation of the isothermal dendritic growth apparatus (IDGA) designed for microgravity experimentation are described. The four major subsystems of the IDGA are a temperature controlled thermostatic bath capable of milli-kelvin stability, a photographic data collection system, a crystal growth chamber, and a growth detection system to initiate data collection. Some of the specific experiments that could utilize the capabilities of the IDGA are dendritic growth in alloys, monotectic systems, life science experiments, and technological applications.

  17. Corrosion resistant coatings suitable for elevated temperature application

    DOEpatents

    Chan, Kwai S.; Cheruvu, Narayana Sastry; Liang, Wuwei

    2012-07-31

    The present invention relates to corrosion resistance coatings suitable for elevated temperature applications, which employ compositions of iron (Fe), chromium (Cr), nickel (Ni) and/or aluminum (Al). The compositions may be configured to regulate the diffusion of metals between a coating and a substrate, which may then influence coating performance, via the formation of an inter-diffusion barrier layer. The inter-diffusion barrier layer may comprise a face-centered cubic phase.

  18. A facility for precise temperature control applications in microgravity

    NASA Technical Reports Server (NTRS)

    Glicksman, M. E.; Lograsso, T. A.; Tirmizi, S. H.; Hahn, R. C.; Winsa, E.

    1988-01-01

    The general design, main components, and operation of the isothermal dendritic growth apparatus (IDGA) designed for microgravity experimentation are described. The four major subsystems of the IDGA are a temperature controlled thermostatic bath capable of milli-kelvin stability, a photographic data collection system, a crystal growth chamber, and a growth detection system to initiate data collection. Some of the specific experiments that could utilize the capabilities of the IDGA are dendritic growth in alloys, monotectic systems, life science experiments, and technological applications.

  19. Recent advances in high temperature instrumentation for hot section applications

    NASA Technical Reports Server (NTRS)

    Englund, David R.; Seasholtz, Richard G.

    1988-01-01

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

  20. High temperature gas-cooled reactor: gas turbine application study

    SciTech Connect

    Not Available

    1980-12-01

    The high-temperature capability of the High-Temperature Gas-Cooled Reactor (HTGR) is a distinguishing characteristic which has long been recognized as significant both within the US and within foreign nuclear energy programs. This high-temperature capability of the HTGR concept leads to increased efficiency in conventional applications and, in addition, makes possible a number of unique applications in both electrical generation and industrial process heat. In particular, coupling the HTGR nuclear heat source to the Brayton (gas turbine) Cycle offers significant potential benefits to operating utilities. This HTGR-GT Application Study documents the effort to evaluate the appropriateness of the HTGR-GT as an HTGR Lead Project. The scope of this effort included evaluation of the HTGR-GT technology, evaluation of potential HTGR-GT markets, assessment of the economics of commercial HTGR-GT plants, and evaluation of the program and expenditures necessary to establish HTGR-GT technology through the completion of the Lead Project.

  1. Applications of Silicon Carbide for High Temperature Electronics and Sensors

    NASA Technical Reports Server (NTRS)

    Shields, Virgil B.

    1995-01-01

    Silicon carbide (SiC) is a wide bandgap material that shows great promise in high-power and high temperature electronics applications because of its high thermal conductivity and high breakdown electrical field. The excellent physical and electronic properties of SiC allows the fabrication of devices that can operate at higher temperatures and power levels than devices produced from either silicon or GaAs. Although modern electronics depends primarily upon silicon based devices, this material is not capable of handling may special requirements. Devices which operate at high speeds, at high power levels and are to be used in extreme environments at high temperatures and high radiation levels need other materials with wider bandgaps than that of silicon. Many space and terrestrial applications also have a requirement for wide bandgap materials. SiC also has great potential for high power and frequency operation due to a high saturated drift velocity. The wide bandgap allows for unique optoelectronic applications, that include blue light emitting diodes and ultraviolet photodetectors. New areas involving gas sensing and telecommunications offer significant promise. Overall, the properties of SiC make it one of the best prospects for extending the capabilities and operational regimes of the current semiconductor device technology.

  2. Wave propagation in anisotropic medium due to an oscillatory point source with application to unidirectional composites

    NASA Technical Reports Server (NTRS)

    Williams, J. H., Jr.; Marques, E. R. C.; Lee, S. S.

    1986-01-01

    The far-field displacements in an infinite transversely isotropic elastic medium subjected to an oscillatory concentrated force are derived. The concepts of velocity surface, slowness surface and wave surface are used to describe the geometry of the wave propagation process. It is shown that the decay of the wave amplitudes depends not only on the distance from the source (as in isotropic media) but also depends on the direction of the point of interest from the source. As an example, the displacement field is computed for a laboratory fabricated unidirectional fiberglass epoxy composite. The solution for the displacements is expressed as an amplitude distribution and is presented in polar diagrams. This analysis has potential usefulness in the acoustic emission (AE) and ultrasonic nondestructive evaluation of composite materials. For example, the transient localized disturbances which are generally associated with AE sources can be modeled via this analysis. In which case, knowledge of the displacement field which arrives at a receiving transducer allows inferences regarding the strength and orientation of the source, and consequently perhaps the degree of damage within the composite.

  3. Hydrometallurgical application for treating a Nigerian chalcopyrite ore in chloride medium: Part I. Dissolution kinetics assessment

    NASA Astrophysics Data System (ADS)

    Baba, Alafara A.; Ayinla, Kuranga I.; Adekola, Folahan A.; Bale, Rafiu B.; Ghosh, Malay K.; Alabi, Abdul G. F.; Sheik, Abdul R.; Folorunso, Ismael O.

    2013-11-01

    The dissolution kinetics of a Nigerian chalcopyrite ore in hydrochloric acid was studied in this article. Acid concentration, reaction temperature, and ore particle size were chosen as experimental parameters. The chemical and morphological studies of the ore before and after leaching at optimal conditions were carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It is revealed that increasing the acid concentration and system temperature and decreasing the ore particle size greatly enhances the dissolution rate. The dissolution kinetics was found to follow the shrinking core model for the diffusion control mechanism where the activation energy ( E a) of 32.92 kJ·mol-1 was obtained for the process and supported by morphological changes at a higher dissolution of 91.33%.

  4. Development of an extended BIEM and its application to the analysis of earthquake dynamic rupture interacting with a medium interface

    NASA Astrophysics Data System (ADS)

    Kusakabe, T.; Kame, N.

    2013-12-01

    An extended boundary integral equation method (XBIEM) has been recently proposed for the analysis of dynamic crack growth (=dynamic earthquake rupture model) in an inhomogeneous medium consisting of homogeneous sub-regions. Originally XBIEM is applicable to non-planar geometry of cracks and medium interfaces, but it has been demonstrated only for a simple planar crack along a bimaterial interface. Here we developed a code to analyse non-planar rupture with non-planar interfaces in a mode III problem, and applied it to a dynamic rupture problem across a planar bimaterial interface to investigate the effect of medium inhomogeneity. For this purpose, we firstly derived all the displacement and displacement velocity kernels in a unified analytic discretized form, in addition to the stress kernels already derived, necessary for versatile geometry of boundaries (i.e., cracks and interfaces) and checked all the kernel components in the simulation of wave propagation across a non-planar interface cutting a homogeneous medium. Then we validated our code in a wave reflection-transmission problem across a planar bimaterial interface. Secondly, in order to realize the analysis of dynamic rupture crossing a bimaterial interface we introduced a new implicit time-stepping scheme for instantaneously interacting boundary elements on the crack and medium interface. Such interactions only appear in the crack's crossing the interface. Otherwise we can use the explicit scheme as employed for BIEM in a homogeneous medium. We validated our numerical code for the crack growth in a homogeneous medium cut with a planar interface and found that our new scheme worked well. Finally, we tackled dynamic rupture propagation on a planar fault embedded normal to the planar interface of a bimaterial. Spontaneous rupture was allowed not only on the planar main fault but also on the interfacial fault and it is controlled by different slip-weakening laws on each of them: each peak strength is

  5. Magnetic field amplification and evolution in turbulent collisionless magnetohydrodynamics: An application to the intracluster medium

    SciTech Connect

    Santos-Lima, R.; De Gouveia Dal Pino, E. M.; Kowal, G.; Falceta-Gonçalves, D.; Lazarian, A.; Nakwacki, M. S.

    2014-02-01

    The amplification of magnetic fields (MFs) in the intracluster medium (ICM) is attributed to turbulent dynamo (TD) action, which is generally derived in the collisional-MHD framework. However, this assumption is poorly justified a priori, since in the ICM the ion mean free path between collisions is of the order of the dynamical scales, thus requiring a collisionless MHD description. The present study uses an anisotropic plasma pressure that brings the plasma within a parametric space where collisionless instabilities take place. In this model, a relaxation term of the pressure anisotropy simulates the feedback of the mirror and firehose instabilities, in consistency with empirical studies. Our three-dimensional numerical simulations of forced transonic turbulence, aiming the modeling of the turbulent ICM, were performed for different initial values of the MF intensity and different relaxation rates of the pressure anisotropy. We found that in the high-β plasma regime corresponding to the ICM conditions, a fast anisotropy relaxation rate gives results that are similar to the collisional-MHD model, as far as the statistical properties of the turbulence are concerned. Also, the TD amplification of seed MFs was found to be similar to the collisional-MHD model. The simulations that do not employ the anisotropy relaxation deviate significantly from the collisional-MHD results and show more power at the small-scale fluctuations of both density and velocity as a result of the action of the instabilities. For these simulations, the large-scale fluctuations in the MF are mostly suppressed and the TD fails in amplifying seed MFs.

  6. Tissue temperature control using a water-cooled applicator: implications for transurethral laser-induced thermotherapy of benign prostatic hyperplasia.

    PubMed

    Sturesson, C; Andersson-Engels, S

    1997-03-01

    A prototype to a water-cooled applicator to be used in transurethral laser-induced thermotherapy of benign prostatic hyperplasia was developed. The flexible applicator was made of Teflon tubes except for the distal outer part which was made of glass, providing a transparent medium for laser radiation and enabling efficient cooling of the surrounding tissue. For heating, laser light from a Nd:YAG laser emitting at 1064 nm, which was coupled into an optical fiber with an institutionally made diffusing tip, was used. Cooling was performed by flushing water through the applicator. By using a mathematical model it was possible to connect the temperature rise of the water in the applicator to the maximum tissue temperature. Tissue light absorption was calculated using Monte Carlo simulations and the heat conduction equation was solved numerically using a finite-difference technique. Experiments on porcine liver in vitro showed that the maximum tissue temperature could be estimated with an average accuracy of 0.4 degree C by measuring the difference in outlet and inlet applicator water temperature and using the thermal model. The results presented suggest that the described method for temperature control can be used during laser prostatectomy to maximize the lesion size while preventing carbonization. PMID:9089598

  7. Turbine-engine applications of thermographic-phosphor temperature measurements

    SciTech Connect

    Noel, B.W.; Turley, W.D.; Allison, S.W.

    1995-12-31

    The thermographic-phosphor (TP) method can measure temperature, heat flux, strain, and other physical quantities remotely in hostile and/or inaccessible environments such as the first-stage turbine components in turbine engines. It is especially useful in situations in which no other known method works well. This paper is a brief review of engine tests that demonstrated the utility of the TP method. For the most part, the results presented here are discussed only qualitatively. The papers in the bibliography describe these and other experiments and results in detail. The first viewgraph summarizes the many desirable features of the TP method. The second viewgraph describes TPs, and the third summarizes how the TP method works. To measure single-point temperatures in turbine-engine applications, we use the decay-time method, which depends on the fact that the luminescence following an impulse of ultraviolet excitation decays, with a characteristic decay time that. Is a monotonically decreasing function of temperature over some range of temperatures. The viewgraph is a set of calibration curves showing the behavior of some useful emission lines for ten important TPs. Consider Lu PO{sub 4}:Eu as an example. Below the {open_quotes}quenching{close_quotes} temperature near 900 Y, the decay time is nearly constant. Above it, the decay time decreases exponentially with the temperature. This strong functional dependence means that one can have a fairly large error in the lifetime measurement, as in environments with poor signal-to-noise ratios (SNRs), yet still obtain high accuracy in the temperature measurement. Our more-recent data up to 1900 K show the same behavior.

  8. Practical applications of low, medium, and high altitude aircraft remote sensing data to land use planning

    NASA Technical Reports Server (NTRS)

    Drackett, K.; Gregg, T. W. D.; Bale, J.

    1975-01-01

    Remotely sensed data is gaining wider acceptance in land use planning activities because of several inherent advantages offered by the technology. Scope of applications have increased to meet planners broadening responsibilities and needs for more comprehensive and specific information in response to new legislative mandates. Specific data needs associated with the land use planning process are varied. To illustrate how remote sensing surveys can be designed to meet a variety of goals at several planning levels, specific examples of the use of remotely sensed data and analysis techniques in four planning oriented land use surveys are discussed. These examples illustrate the use of aerial photography at the state planning level in Maryland and county level in Jefferson Parish, Louisiana. Special applications of aerial photography are demonstrated by energy planning in San Bernardino County, California and water management planning in New Castle County, Delaware.

  9. Supporting data intensive applications with medium grained parallelism. Progress report, July 1, 1991--February 28, 1992

    SciTech Connect

    Pfaltz, J.L.; French, J.C.; Grimshaw, A.S.; Son, S.H.

    1992-04-01

    ADAMS is an ambitious effort to provide new database access paradigms for the kinds of scientific applications that require massively parallel access to very large data sets in order to be effective. Many of the Grand Challenge Problems fall into this category, as well as those kinds of scientific research which depend on widely distributed shared sets of disparate data. The essence of the ADAMS approach is to view data purely in functional terms, rather than the more traditional structural view in which multiple data items are aggregated into records or tuples of flat files. Further, ADAMS has been implemented as an embedded interface so that scientists can develop applications in the host programming language of their choice, often Fortran, Pascal, or C, and still access shared data generated in other environments. The syntax and semantics of ADAMS is essentially complete. The functional nature of the ADAMS data interface paradigm simplifies its implementation in a distributed environment, e.g., the Mentat run-time system, because one must only distribute functional servers, not pieces of data structures. However, this only opens up the possibility of effective parallel database processing; to realize this potential far more work must be done in the areas of data dependence, intra-statement parallelism, parallel query optimization, and maintaining consistency and reliability in concurrent systems. Discovering how to make effective parallel data access an actually in real scientific applications is the point of this research.

  10. Hot deformation behaviour of alloys for applications at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Voyzelle, Benoit

    The present study investigated the deformation behaviour, microstructure evolution and fracture behaviour under hot working conditions of alloys designed for elevated-temperature applications. For this purpose, iron-aluminum and titanium-aluminum alloys were selected and their compositions are: Fe-8.5wt%Al-5.5Cr-2.0Mo-0.2Zr-0.03C, Fe-16.5Al-5.5Cr-1.0Nb-0.05C and Ti-33.3Al-2.8Mn-4.8Nb. These alloys were tested in the as-cast condition and in the form of hot-rolled + annealed plate for the iron-aluminum alloys and in the HIP'ed condition for the titanium-aluminum alloy. Isothermal compression tests were carried out with a Gleeble 2000 over a range of temperatures from 800 to 1250°C and constant strain rates from 10-3 to 10 s-1. In general, the flow curves are marked by a peak stress and softening which decline as temperature rises, and a flow stress which diminishes with rise in temperature and decrease in strain rate. The flow behaviour at peak stress (sigmap) and 0.5 true strain of these materials was described well by the Zener-Hollomon parameter Z=3˙exp /RTQHW , where Z=K3sinha sn . A numerical curve-fitting method was used to yield values of the following parameters: (i) stress exponent, n and (ii) activation energy, QHW . The dynamic material modeling approach was performed to extract from hot compression data: (i) the strain rate sensitivity parameter, m, (ii) the efficiency of power dissipation, eta, and (iii) the instability parameter, xi. The microstructure evolution and fracture behaviour were assessed using optical and electron microscopy. The deformation processes occuring were determined by correlation of the sigma-epsilon curves, m and microstructural observations. The resulting deformation map indicates that at lower temperatures and higher strain rates, the dominant restoration occurs by dynamic recovery, while at lower strain rates and higher temperatures dynamic recrystallization is the operative mode. At the highest temperatures, dynamic

  11. Assessment of microelectronics packaging for high temperature, high reliability applications

    SciTech Connect

    Uribe, F.

    1997-04-01

    This report details characterization and development activities in electronic packaging for high temperature applications. This project was conducted through a Department of Energy sponsored Cooperative Research and Development Agreement between Sandia National Laboratories and General Motors. Even though the target application of this collaborative effort is an automotive electronic throttle control system which would be located in the engine compartment, results of this work are directly applicable to Sandia`s national security mission. The component count associated with the throttle control dictates the use of high density packaging not offered by conventional surface mount. An enabling packaging technology was selected and thermal models defined which characterized the thermal and mechanical response of the throttle control module. These models were used to optimize thick film multichip module design, characterize the thermal signatures of the electronic components inside the module, and to determine the temperature field and resulting thermal stresses under conditions that may be encountered during the operational life of the throttle control module. Because the need to use unpackaged devices limits the level of testing that can be performed either at the wafer level or as individual dice, an approach to assure a high level of reliability of the unpackaged components was formulated. Component assembly and interconnect technologies were also evaluated and characterized for high temperature applications. Electrical, mechanical and chemical characterizations of enabling die and component attach technologies were performed. Additionally, studies were conducted to assess the performance and reliability of gold and aluminum wire bonding to thick film conductor inks. Kinetic models were developed and validated to estimate wire bond reliability.

  12. The effect of medium selection on adipose-derived stem cell expansion and differentiation: implications for application in regenerative medicine.

    PubMed

    Roxburgh, J; Metcalfe, A D; Martin, Y H

    2016-08-01

    The use of adipose-derived stem cells is wide-spread in both basic biology and regenerative medicine, due to the abundance of adipose tissue and the multipotent differentiation potential of the cells. However, the methods used to isolate and culture cells vary greatly between different research groups. Identification of medium formulations which provide rapid cell expansion while maintaining cell phenotype would have clear advantages. We compared growth and differentiation potential along the adipogenic lineage in human ADSCs in nine different media. We further assessed induced and spontaneous differentiation along the adipogenic, chondrogenic and osteogenic lineage in three different media. There was significant variation in the rate of growth between different media. All media supported ADSC phenotype and adipogenic differentiation, although there was variation between the different media. Differentiation along the adipogenic, chondrogenic and osteogenic lineages in the three media was confirmed, with some upregulation of specific genes observed when cells were left to spontaneously differentiate. Our study shows a direct comparison of human ADSCs grown in different media, both reported in the literature and commercially available. It indicates that rapid proliferation occurs most often in media which contain 10 % foetal bovine serum and that differentiation along different lineages can be induced but also occurs spontaneously once cells become confluent. These data provide a tool for other researchers to facilitate the choice of medium formulation most appropriate for different applications. PMID:25795468

  13. High performance catalyzed-reaction layer for medium temperature operating solid oxide fuel cells. 3: Effects of composition and morphology on performance of anode and cathode layers

    SciTech Connect

    Watanabe, Masahiro; Uchida, Hiroyuki; Suzuki, Hiroaki; Tsuno, A.

    1995-12-31

    Polarization properties of catalyzed-reaction layers, which the authors developed for medium temperature operating SOFC, were greatly improved by controlling their compositions and microstructures. The amount of Pt catalysts loaded on Sr-doped LaMnO{sub 3} (LSM) cathode was reduced down to 1/5 by decreasing size of Pt particles. A large depolarizing effect was observed on the Pt-catalyzed LSM cathode, especially at high current densities. The anodic overpotential for the samaria-doped ceria (SDC) layer was appreciably lowered by applying both highly dispersed Ru microcrystals and 0.1{micro}m-sized SDC particles onto the SDC layer.

  14. Minimum relative entropy: Theory and application to surface temperature reconstruction from borehole temperature measurements

    NASA Astrophysics Data System (ADS)

    Kennedy, Paula L.; Woodbury, Allan D.; Wang, Kelin

    2000-10-01

    In this paper we extend the minimum relative entropy (MRE) method to reconstruct ground surface temperature changes (GST) from borehole temperature measurements (BHT). The application of MRE to recovering GST is promising and provides an alternative to other inverse methods in geophysics. The relative entropy formulation provides the advantage of allowing for a prior bias in the estimated pdf and ‘hard’ bounds if desired. Test cases showed good recoveries of the GST. The method was utilized in recovering GST from two data sets in Canada. The Lac Dufault data gave very consistent results for different choices of a priori information and bounds. The Mariner results were not as good quality. This method has only recovered past ground surface temperatures, which does not directly provide information regarding climate change. However, results contained herein show fairly uniform temperatures until the past 100 to 500 years and in more recent times about a 4°C rise in temperature, consistent with previous published results.

  15. Oxidation of Palladium-Chromium Alloys for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Piltch, Nancy D.; Jih-Fen, Lei; Zeller, Mary V.

    1994-01-01

    An alloy consisting of Pd with 13 wt % Cr is a promising material for high temperature applications. High temperature performance is degraded by the oxidation of the material, which is more severe in the fine wires and thin films used for sensor applications than in the bulk. The present study was undertaken to improve our understanding of the physical and chemical changes occurring at these temperatures and to identify approaches to limit oxidation of the alloy. The alloy was studied in both ribbon and wire forms. Ribbon samples were chosen to examine the role of grain boundaries in the oxidation process because of the convenience of handling for the oxidation studies. Wire samples 25 microns in diameter which are used in resistance strain gages were studied to correlate chemical properties with observed electrical, physical, and structural properties. Overcoating the material with a metallic Cr film did prevent the segregation of Pd to the surface; however, it did not eliminate the oxidation of the alloy.

  16. Ultrasonic thermometry simulation in a random fluctuating medium: Evidence of the acoustic signature of a one-percent temperature difference.

    PubMed

    Nagaso, M; Moysan, J; Benjeddou, S; Massacret, N; Ploix, M A; Komatitsch, D; Lhuillier, C

    2016-05-01

    We study the development potential of ultrasonic thermometry in a liquid fluctuating sodium environment similar to that present in a Sodium-cooled Fast Reactor, and thus investigate if and how ultrasonic thermometry could be used to monitor the sodium flow at the outlet of the reactor core. In particular we study if small temperature variations in the sodium flow of e.g. about 1% of the sodium temperature, i.e., about 5°C, can have a reliably-measurable acoustic signature. Since to our knowledge no experimental setups are available for such a study, and considering the practical difficulties of experimentation in sodium, we resort to a numerical technique for full wave propagation called the spectral-element method, which is a highly accurate finite-element method owing to the high-degree basis functions it uses. We obtain clear time-of-flight variations in the case of a small temperature difference of one percent in the case of a static temperature gradient as well as in the presence of a random fluctuation of the temperature field in the turbulent flow. The numerical simulations underline the potential of ultrasonic thermometry in such a context. PMID:26921558

  17. Improvement of Surface Temperature Prediction Using SVR with MOGREPS Data for Short and Medium range over South Korea

    NASA Astrophysics Data System (ADS)

    Lim, S. J.; Choi, R. K.; Ahn, K. D.; Ha, J. C.; Cho, C. H.

    2014-12-01

    As the Korea Meteorology Administration (KMA) has operated Met Office Global and Regional Ensemble Prediction System (MOGREPS) with introduction of Unified Model (UM), many attempts have been made to improve predictability in temperature forecast in last years. In this study, post-processing method of MOGREPS for surface temperature prediction is developed with machine learning over 52 locations in South Korea. Past 60-day lag time was used as a training phase of Support Vector Regression (SVR) method for surface temperature forecast model. The selected inputs for SVR are followings: date and surface temperatures from Numerical Weather prediction (NWP), such as GDAPS, individual 24 ensemble members, mean and median of ensemble members for every 3hours for 12 days.To verify the reliability of SVR-based ensemble prediction (SVR-EP), 93 days are used (from March 1 to May 31, 2014). The result yielded improvement of SVR-EP by RMSE value of 16 % throughout entire prediction period against conventional ensemble prediction (EP). In particular, short range predictability of SVR-EP resulted in 18.7% better RMSE for 1~3 day forecast. The mean temperature bias between SVR-EP and EP at all test locations showed around 0.36°C and 1.36°C, respectively. SVR-EP is currently extending for more vigorous sensitivity test, such as increasing training phase and optimizing machine learning model.

  18. Accelerated Stress Testing of Hydrocarbon-Based Encapsulants for Medium-Concentration CPV Applications

    SciTech Connect

    Kempe, M. D.; Moricone, T. J.; Kilkenny, M.; Zhang, J. Z.

    2011-02-01

    Concentrating photovoltaic (CPV) systems have great potential to reduce photovoltaic (PV) electricity costs because of the relatively low cost of optical components as compared to PV cells. A transparent polymeric material is used to optically couple the PV cell to optical components and is thus exposed to the concentrated light source at elevated temperatures. In this work polymeric encapsulant materials are positioned close to a Xenon arc lamp to expose them to ultraviolet radiation (UV) that is about 42 times as intense as sunlight. Furthermore, different glass types are used as filters to modify the spectral distribution of light in the UV range. A strong sensitivity of non-silicone-based encapsulants to light below ~350 nm is demonstrated. Of all the materials examined in this study, the polydimethyl silicone samples performed the best. The next best material was an ionomer which maintained optical transmission but became photo-oxidized where exposed to the atmosphere.

  19. Transmission matrix of a scattering medium and its applications in biophotonics.

    PubMed

    Kim, Moonseok; Choi, Wonjun; Choi, Youngwoon; Yoon, Changhyeong; Choi, Wonshik

    2015-05-18

    A conventional lens has well-defined transfer function with which we can form an image of a target object. On the contrary, scattering media such as biological tissues, multimode optical fibers and layers of disordered nanoparticles have highly complex transfer function, which makes them impractical for the general imaging purpose. In recent studies, we presented a method of experimentally recording the transmission matrix of such media, which is a measure of the transfer function. In this review paper, we introduce two major applications of the transmission matrix: enhancing light energy delivery and imaging through scattering media. For the former, we identified the eigenchannels of the transmission matrix with large eigenvalues and then coupled light to those channels in order to enhance light energy delivery through the media. For the latter, we solved matrix inversion problem to reconstruct an object image from the distorted image by the scattering media. We showed the enlargement of the numerical aperture of imaging systems with the use of scattering media and demonstrated endoscopic imaging through a single multimode optical fiber working in both reflectance and fluorescence modes. Our approach will pave the way of using scattering media as unique optical elements for various biophotonics applications. PMID:26074520

  20. Electronic Components for use in Extreme Temperature Aerospace Applications

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    Electrical power management and control systems designed for use in planetary exploration missions and deep space probes require electronics that are capable of efficient and reliable operation under extreme temperature conditions. Space-based infra-red satellites, all-electric ships, jet engines, electromagnetic launchers, magnetic levitation transport systems, and power facilities are also typical examples where the electronics are expected to be exposed to harsh temperatures and to operate under severe thermal swings. Most commercial-off-the-shelf (COTS) devices are not designed to function under such extreme conditions and, therefore, new parts must be developed or the conventional devices need to be modified. For example, spacecraft operating in the cold environment of deep space carry a large number of radioisotope heating units in order to maintain the surrounding temperature of the on-board electronics at approximately 20 C. At the other end, built-in radiators and coolers render the operation of electronics possible under hot conditions. These thermal measures lead to design complexity, affect development costs, and increase size and weight. Electronics capable of operation at extreme temperatures, thus, will not only tolerate the hostile operational environment, but also make the overall system efficient, more reliable, and less expensive. The Extreme Temperature Electronics Program at the NASA Glenn Research Center focuses on research and development of electronics suitable for applications in the aerospace environment and deep space exploration missions. Research is being conducted on devices, including COTS parts, for potential use under extreme temperatures. These components include semiconductor switching devices, passive devices, DC/DC converters, operational amplifiers, and oscillators. An overview of the program will be presented along with some experimental findings.

  1. Effect of Boron on the Kinetics of Low-Temperature Decomposition of Martensite in Quenched Medium-Carbon Steel

    NASA Astrophysics Data System (ADS)

    Alekseev, A. A.; Grinberg, E. M.

    2016-03-01

    The effect of boron on the microstructure, microhardness, and kinetics of low-temperature decomposition of martensite in the 40Kh and 30KhRA steels quenched at different cooling rates has been studied. It has been shown that the low-temperature decomposition of martensite in the boron-containing steel after quenching from 1050°C at a high cooling rate is strongly decelerated at the initial stage of decomposition. At low quenching cooling rates, the martensite decomposition in the steels under investigation is characterized by a similar kinetics.

  2. Low temperature silicon dioxide deposition using tetramethylsilane for micro- and nanofabrication applications

    NASA Astrophysics Data System (ADS)

    Lin, Xin

    This thesis explores low temperature, plasma-enhanced chemical vapor deposited (PECVD) silicon dioxide thin films using tetramethylsilane (TMS), Si(CH3)4, as the silicon precursor for micro- and nanofabrication applications. A plasma chemistry model has been developed on the basis of the deposition rate behavior observed in the experiments. The oxygen plasma characteristics are shown to play a key role in oxide deposition with a low TMS concentration. Oxide formation occurs via two competing pathways: atom-induced deposition and ion-induced deposition. Their relative contributions vary with deposition conditions. The ion-induced deposition rate increases with substrate temperature but decreases when deposition pressure increases. In contrast, the atom-induced deposition rate decreases with increasing temperature but increases with pressure. Electrical, optical, chemical, mechanical properties as well as the conformality of the PECVD TMS oxide films were systematically investigated with substrate temperatures varying from 100°C to 200°C and deposition pressures changing from 2 Torr to 8 Torr The I-V characteristics of deposited oxide films degrade with decreasing substrate temperature and/or increasing deposition pressure due to a reduction of the film density and increase of the Si-OH concentration in the oxide films, which was verified with the FTIR spectra, wet-etch rate, refractive index, and dielectric constant. The C-V characteristics also deteriorate with lower substrate temperatures. However, the best C-V characteristic was obtained with a medium pressure of 3 Torr in this thesis study because of moderate ion-bombardment that helps the formation of high quality Si/SiO2 interface. The PECVD TMS oxide films exhibit moderate tensile intrinsic stress, whose variation with deposition conditions is consistent with changes in the film density and Si-OH concentration. The film conformality strongly depends on the deposition pressure and temperature. The best

  3. Self-lubricating coatings for high-temperature applications

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.

    1987-01-01

    Some present-day aeropropulsion systems impose severe demands on the thermal and oxidative stability of lubricant, bearing, and seal materials. These demands will be much more severe for operational systems around the turn of the century. Solid lubricants with maximum temperature capabilities of about 1100 C are known. Unfortunately, none of the solid lubricants with the highest temperature capabilities are effective below approximately 400 C. However, research shows that silver and stable fluorides, such as calcium and barium fluoride act synergistically to provide lubrication from below room temperature to approximately 900 C. Plasma-sprayed, self-lubricating composite coatings that were developed at Lewis are described. Background information is given on coatings, designed as PS100 and PS101, that contain the solid lubricants in a Nichrome matrix. These coatings have low friction coefficients over a wide temperature range, but they have inadequate wear resistance for some long-duration applications. Wear resistance was dramatically improved in a recently developed coating PS200, by replacing the Nichrome matrix material with metal-bonded chromium carbide containing dispersed silver and calcium fluoride/barium fluoride eutectic (CaF2/BaF2). The lubricants control friction and the carbide matrix provides excellent wear resistance. Successful tests of these coatings are discussed.

  4. High-Temperature Strain Sensing for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Piazza, Anthony; Richards, Lance W.; Hudson, Larry D.

    2008-01-01

    Thermal protection systems (TPS) and hot structures are utilizing advanced materials that operate at temperatures that exceed abilities to measure structural performance. Robust strain sensors that operate accurately and reliably beyond 1800 F are needed but do not exist. These shortcomings hinder the ability to validate analysis and modeling techniques and hinders the ability to optimize structural designs. This presentation examines high-temperature strain sensing for aerospace applications and, more specifically, seeks to provide strain data for validating finite element models and thermal-structural analyses. Efforts have been made to develop sensor attachment techniques for relevant structural materials at the small test specimen level and to perform laboratory tests to characterize sensor and generate corrections to apply to indicated strains. Areas highlighted in this presentation include sensors, sensor attachment techniques, laboratory evaluation/characterization of strain measurement, and sensor use in large-scale structures.

  5. Very high temperature measurements: Application to nuclear reactor safety tests

    NASA Astrophysics Data System (ADS)

    Parga, Clemente Jose

    This PhD dissertation focuses on the improvement of very high temperature thermometry (1100ºC to 2480ºC), with special emphasis on the application to the field of nuclear reactor safety and severe accident research. Two main projects were undertaken to achieve this objective: -The development, testing and transposition of high-temperature fixed point (HTFP) metal-carbon eutectic cells, from metrology laboratory precision (+/-0.001ºC) to applied research with a reasonable degradation of uncertainties (+/-3-5ºC). -The corrosion study and metallurgical characterization of Type-C thermocouple (service temp. 2300ºC) prospective sheath material was undertaken to extend the survivability of TCs used for molten metallic/oxide corium thermometry (below 2000ºC).

  6. Laser-based strain measurements for high temperature applications

    NASA Astrophysics Data System (ADS)

    Lant, Christian T.

    1992-09-01

    The Instrumentation and Control Technology Division at NASA Lewis Research Center has developed a high performance optical strain measurement system for high temperature applications using wires and fibers. The system is based on Yamaguchi's two-beam speckle-shift strain measurement technique. The system automatically calculates surface strains at a rate of 5 Hz using a digital signal processor in a high speed micro-computer. The system is fully automated, and can be operated remotely. This report describes the speckle-shift technique and the latest NASA system design. It also shows low temperature strain test results obtained from small diameter tungsten, silicon carbide, and sapphire specimens. These specimens are of interest due to their roles in composite materials research at NASA Lewis.

  7. Unified constitutive models for high-temperature structural applications

    NASA Technical Reports Server (NTRS)

    Lindholm, U. S.; Chan, K. S.; Bodner, S. R.; Weber, R. M.; Walker, K. P.

    1988-01-01

    Unified constitutive models are characterized by the use of a single inelastic strain rate term for treating all aspects of inelastic deformation, including plasticity, creep, and stress relaxation under monotonic or cyclic loading. The structure of this class of constitutive theory pertinent for high temperature structural applications is first outlined and discussed. The effectiveness of the unified approach for representing high temperature deformation of Ni-base alloys is then evaluated by extensive comparison of experimental data and predictions of the Bodner-Partom and the Walker models. The use of the unified approach for hot section structural component analyses is demonstrated by applying the Walker model in finite element analyses of a benchmark notch problem and a turbine blade problem.

  8. GREENER AND RAPID ACCESS TO BIO-ACTIVE HETEROCYCLES: ROOM TEMPERATURE SYNTHESIS OF PYRAZOLES AND DIAZEPINES IN AQUEOUS MEDIUM

    EPA Science Inventory

    An expeditious room temperature synthesis of pyrazoles and diazepines by condensation of hydrazines/hydrazides and diamines with various 1,3-diketones is described. This greener protocol was catalyzed by polystyrene supported sulfonic acid (PSSA) and proceeded efficiently in wate...

  9. Effects of incubation temperature, inoculum size, and medium on agreement of macro- and microdilution broth susceptibility test results for yeasts.

    PubMed Central

    Cook, R A; McIntyre, K A; Galgiani, J N

    1990-01-01

    We examined the effects of temperature and inoculum on the agreement of macro- and microdilution broth MICs of five antifungal agents against six isolates of Candida species or Torulopsis glabrata. Incubation temperature affected results with amphotericin B, flucytosine, fluconazole, and SCH 39304, producing better agreement at 35 degrees C than at 37 degrees C. Agreement between methods was better with an inoculum size of 10(2) than with one of 10(4) yeast cells per ml in testing fluconazole or SCH 39304, and the discrepancies seen with a higher incubation temperature and a larger inoculum appeared to be additive. However, inoculum size did not seem to affect agreement between methods in testing amphotericin B, flucytosine, or ketoconazole. Regardless of test conditions, macrodilution broth MICs of amphotericin B for different isolates were strikingly higher than microdilution test MICs, with mean differences being greater than ninefold under some test conditions. We conclude that for most currently available antifungal agents, an incubation temperature of 35 degrees C and a starting yeast inoculum of less than 10(4) cells per ml improve the agreement between macro- and microdilution broth tests. PMID:2221863

  10. Long-Term Formaldehyde Emissions from Medium-Density Fiberboard in a Full-Scale Experimental Room: Emission Characteristics and the Effects of Temperature and Humidity.

    PubMed

    Liang, Weihui; Yang, Shen; Yang, Xudong

    2015-09-01

    We studied formaldehyde emissions from the medium-density fiberboard (MDF) in a full-scale experimental room to approximate emissions in actual buildings. Detailed indoor formaldehyde concentrations and temperature and humidity data were obtained for about 29 months. Temperature, relative humidity (RH), and absolute humidity (AH) ranged over -10.9-31.4 °C, 46.5-83.6%, and 1.1-23.1 g/kgair, respectively. Annual cyclical seasonal variations were observed for indoor formaldehyde concentrations and emission rates, exhibiting entirely different characteristics than those in an environmental chamber under constant environmental conditions. The maximum concentration occurred in summer rather than at initial introduction of the material. The concentrations in summer could be a few up to 20 times higher than that in winter, depending on the indoor temperature and humidity conditions. Concentrations decreased by 20-65% in corresponding months of the second year. Indoor formaldehyde concentrations were positively correlated with temperature and AH but were poorly correlated with RH. The combined effects of temperature and AH on formaldehyde emissions from MDF in actual buildings were verified. These detailed long-term experimental results could be used with environmental chamber measurement data to scale up and validate emission models from chambers held at constant conditions to actual buildings. PMID:26263171

  11. Temperature and heat flux measurements: Challenges for high temperature aerospace application

    NASA Technical Reports Server (NTRS)

    Neumann, Richard D.

    1992-01-01

    The measurement of high temperatures and the influence of heat transfer data is not strictly a problem of either the high temperatures involved or the level of the heating rates to be measured at those high temperatures. It is a problem of duration during which measurements are made and the nature of the materials in which the measurements are made. Thermal measurement techniques for each application must respect and work with the unique features of that application. Six challenges in the development of measurement technology are discussed: (1) to capture the character and localized peak values within highly nonuniform heating regions; (2) to manage large volumes of thermal instrumentation in order to efficiently derive critical information; (3) to accommodate thermal sensors into practical flight structures; (4) to broaden the capabilities of thermal survey techniques to replace discrete gages in flight and on the ground; (5) to provide supporting instrumentation conduits which connect the measurement points to the thermally controlled data acquisition system; and (6) to develop a class of 'vehicle tending' thermal sensors to assure the integrity of flight vehicles in an efficient manner.

  12. Effect of temperature on the shape of spatial quasi-periodic oscillations of the refractive index of alkali atoms in an optically dense medium with a closed excitation contour of Δ type

    SciTech Connect

    Barantsev, K A; Litvinov, A N

    2014-10-31

    A theory of a closed excitation contour (Δ system) of a three-level atom in an optically dense medium is constructed with allowance for temperature. The spatial quasi-periodic oscillations of the refractive index in the system under study are shown to damp with increasing temperature. The range of temperatures at which these oscillations are most pronounced is found. (quantum optics)

  13. Resin Transfer Moldable Polyimides Developed for High-Temperature Applications

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann

    2000-01-01

    High-temperature polyimides, such as PMR 15 (which was developed at the NASA Glenn Research Center at Lewis Field), are becoming an increasingly important class of materials for a variety of aerospace applications, such as aircraft engine components and propulsion and airframe components for reusable launch vehicles (RLV s). Because of their high specific strength and low density, use of these materials in place of more traditional aerospace materials, such as titanium, can significantly reduce component and vehicle weight, leading to reductions in fuel consumption (and pollutants), increases in payload and passenger capacity, and improvements in vehicle performance.

  14. High Temperature Polymeric Materials for Space Transportation Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.; Campbell, Sandi G.; Chuang, Kathy C.; Scheimann, Daniel A.; Mintz, Eric; Hylton, Donald; Veazie, David; Criss, James; Kollmansberg, Ron; Tsotsis, Tom

    2003-01-01

    High temperature polymer matrix composites are attractive materials for space transporation propulsion systems because of their low density and high specific strength. However, the relatively poor stability and processability of these materials can render them unsuitable for many of these applications. New polymeric materials have been developed under the Propulsion Research and Technology Program through the use of novel resin chemistry and nanotechnology. These new materials can significantly enhance the durability and weight and improve the processability and affordability of propulsion components for advanced space transportation systems.

  15. Fast high-temperature superconductor switch for high current applications

    NASA Astrophysics Data System (ADS)

    Solovyov, Vyacheslav F.; Li, Qiang

    2013-07-01

    Reversible operation of a high current superconductor switch based on the quench of high-resistance second generation high temperature superconducting wire is demonstrated. The quench is induced by a burst of an ac field generated by an inductively coupled radio-frequency coil. The switch makes a superconducting-to-normal transition within 5 ms and also has a rapid recovery to the superconducting state. The device has potential applications as an active current limiter or as a storage switch for superconducting magnetic energy storage systems. Operation in a full flux penetration/flow regime can effectively minimize the detrimental effects of the intrinsic conductor non-uniformity.

  16. The Low-temperature Ion Sulfurizing Technology and its Applications

    NASA Astrophysics Data System (ADS)

    Ma, G. Z.; Xu, B. S.; Wang, H. D.; Li, G. L.; Zhang, S.

    A solid lubrication film mainly consists of FeS, which has excellent tribology properties, can be formed on the sulfurized iron or steel surface. The sulfurizing technology has aroused intense attention from the day it appeared. However, the widespread industrial application of sulfurizing technology was promoted by the low-temperature ion sulfurizing (LTIS) process. This paper summarized the phylogeny and sorts of sulfurizing technology firstly; then, the process flow of LTIS technology, the forming mechanism, microstructure and tribological properties of ion sulfurized layer were introduced detailedly; and then, the technological, economic and environmental merits of LTIS technology were generalized; finally, the industrial applications of LTIS technology in various typical rolling, sliding and heavy duty parts were reviewed briefly. LTIS technology, with the advantages of high sulfurizing speed, good performance of sulfurized layer and without sideeffect, has played an important role in the tribology modification of ferrous parts, and the LTIS process will become more green, simple and efficient in the future.

  17. Low-Temperature Solution Processable Electrodes for Piezoelectric Sensors Applications

    NASA Astrophysics Data System (ADS)

    Tuukkanen, Sampo; Julin, Tuomas; Rantanen, Ville; Zakrzewski, Mari; Moilanen, Pasi; Lupo, Donald

    2013-05-01

    Piezoelectric thin-film sensors are suitable for a wide range of applications from physiological measurements to industrial monitoring systems. The use of flexible materials in combination with high-throughput printing technologies enables cost-effective manufacturing of custom-designed, highly integratable piezoelectric sensors. This type of sensor can, for instance, improve industrial process control or enable the embedding of ubiquitous sensors in our living environment to improve quality of life. Here, we discuss the benefits, challenges and potential applications of piezoelectric thin-film sensors. The piezoelectric sensor elements are fabricated by printing electrodes on both sides of unmetallized poly(vinylidene fluoride) film. We show that materials which are solution processable in low temperatures, biocompatible and environmental friendly are suitable for use as electrode materials in piezoelectric sensors.

  18. Dust accelerators and their applications in high-temperature plasmas

    SciTech Connect

    Wang, Zhehui; Ticos, Catakin M

    2010-01-01

    The perennial presence of dust in high-temperature plasma and fusion devices has been firmly established. Dust inventory must be controlled, in particular in the next-generation steady-state fusion machines like ITER, as it can pose significant safety hazards and potentially interfere with fusion energy production. Much effort has been devoted to gening rid of the dust nuisance. We have recognized a number of dust-accelerators applications in magnetic fusion, including in plasma diagnostics, in studying dust-plasma interactions, and more recently in edge localized mode (ELM)'s pacing. With the applications in mind, we will compare various acceleration methods, including electrostatic, gas-drag, and plasma-drag acceleration. We will also describe laboratory experiments and results on dust acceleration.

  19. Dust Accelerators And Their Applications In High-Temperature Plasmas

    NASA Astrophysics Data System (ADS)

    Ticoş, Cǎtǎlin M.; Wang, Zhehui

    2011-06-01

    The perennial presence of dust in high-temperature plasma and fusion devices has been firmly established. Dust inventory must be controlled, in particular in the next-generation steady-state fusion machines like ITER, as it can pose significant safety hazards and potentially interfere with fusion energy production. Although much effort has been devoted to getting rid of the dust nuisance, there are instances where a controlled use of dust can be beneficial. We have recognized a number of dust-accelerators applications in magnetic fusion, including in plasma diagnostics, in studying dust-plasma interactions, and more recently in edge localized mode (ELM)'s pacing. With the applications in mind, we will compare various acceleration methods, including electrostatic, gas-drag, and plasma-drag acceleration. We will also describe laboratory experiments and results on dust acceleration.

  20. Bioprocess applications of a Sindbis virus-based temperature-inducible expression system.

    PubMed

    Boorsma, M; Hoenke, S; Marrero, A; Fischer, R; Bailey, J E; Renner, W A; Bachmann, M F

    2002-09-20

    The production and study of toxic proteins requires inducible expression systems with low basal level expression and high inducibility. Here, we describe bioprocess applications of the pCytTS temperature-regulatable Sindbis virus replicon-based expression system. We used green fluorescent protein as a marker protein to optimize the selection of stable transfected clones with increased expression levels. Using the optimized protocol, clones were constructed that produced the growth-inhibiting, anti-viral protein interferon beta (beta-IFN). Selected clones were analyzed for temperature-dependent beta-IFN production in adherent and suspension cultures in serum free medium. Specific expression levels were around 1.0 x 10(5) IU/10(6) cells/day (0.5 microg/10(6) cells/day) in suspension cultures and over 1.5 x 10(6) IU/mL/day (7.5 microg/mL/day) in hollow fiber reactors using adherent cells. Hexahistidine-tagged beta-IFN purified from T-flask cultures was highly glycosylated and showed high specific activity. beta-IFN mRNA amplified by the viral replicase for 10 days did not show an accumulation of mutations. These data suggest the applicability of the pCytTS-inducible expression system for the production of high-quality glycoproteins in different reactors. PMID:12209807

  1. Implementation Challenges for Ceramic Matrix Composites in High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay

    2004-01-01

    Ceramic matrix composites are leading candidate materials for a number of applications in aeronautics, space, energy, electronics, nuclear, and transportation industries. In the aeronautics and space exploration systems, these materials are being considered for applications in hot sections of jet engines such as the combustor liner, nozzle components, nose cones, leading edges of reentry vehicles and space propulsion components. Applications in the energy and environmental industries include radiant heater tubes, heat exchangers, heat recuperators, gas and diesel particulate filters (DPFs), and components for land based turbines for power generation. These materials are also being considered for use in the first wall and blanket components of fusion reactors. There are a number of critical issues and challenges related to successful implementation of composite materials. Fabrication of net and complex shape components with high density and tailorable matrix properties is quite expensive, and even then various desirable properties are not achievable. In this presentation, microstructure and thermomechanical properties of composites fabricated by two techniques (chemical vapor infiltration and melt infiltration), will be presented. In addition, critical need for robust joining and assembly technologies in successful implementation of these systems will be discussed. Other implementation issues will be discussed along with advantages and benefits of using these materials for various components in high temperature applications.

  2. Elevated temperature erosion studies on some materials for high temperature applications

    SciTech Connect

    Zhou Jianren.

    1991-01-01

    The surface degradation of materials due to high temperature erosion or combined erosion corrosion is a serious problem in many industrial and aeronautical applications. As such, it has become an important design consideration in many situations. The materials investigated in the present studies are stainless steels, Ti-6Al-4V, alumina ceramics, with and without silicate glassy phase, and zirconia. These are some of the potential materials for use in the high temperature erosive-corrosive environments. The erosion or erosion-corrosion experiments were performed in a high temperature sand-blast type of test rig. The variables studied included the temperature, material composition, heat treatment condition, impingement velocity and angle, erodent concentration, etc. The morphological features of the eroded or eroded-corroded surfaces, substrate deformation, and oxide characteristics were studied by optical and scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, thermogravimetric analysis. The scratch test, single ball impact, and indentation tests were used to understand the behavior of oxide film in particle impacts. Based on these studies, the understanding of the mechanisms involved in the mechanical or combined mechanical and chemical actions in erosion was developed.

  3. Autonomous distributed temperature sensing for long-term heated applications in remote areas

    NASA Astrophysics Data System (ADS)

    Kurth, A.-M.; Dawes, N.; Selker, J.; Schirmer, M.

    2012-10-01

    Distributed Temperature Sensing (DTS) is a fiber-optical method enabling simultaneous temperature measurements over long distances. Electrical resistance heating of the metallic components of the fiber-optic cable provides information on the thermal characteristics of the cable's environment, providing valuable insight into processes occurring in the surrounding medium, such as groundwater-surface water interactions, dam stability or soil moisture. Until now, heated applications required direct handling of the DTS instrument by a researcher, rendering long-term investigations in remote areas impractical due to the often difficult and time-consuming access to the field site. Remote-control and automation of the DTS instrument and heating processes, however, resolve the issue with difficult access. The data can also be remotely accessed and stored on a central database. The power supply can be grid-independent, although significant infrastructure investment is required here due to high power consumption during heated applications. Solar energy must be sufficient even in worst case scenarios, e.g. during long periods of intense cloud cover, to prevent system failure due to energy shortage. In combination with storage batteries and a low heating frequency, e.g. once per day or once per week (depending on the season and the solar radiation on site), issues of high power consumption may be resolved. Safety regulations dictate adequate shielding and ground-fault protection, to safeguard animals and humans from electricity and laser sources. In this paper the autonomous DTS system is presented to allow research with heated applications of DTS in remote areas for long-term investigations of temperature distributions in the environment.

  4. Autonomous distributed temperature sensing for long-term heated applications in remote areas

    NASA Astrophysics Data System (ADS)

    Kurth, A.-M.; Dawes, N.; Selker, J.; Schirmer, M.

    2013-02-01

    Distributed temperature sensing (DTS) is a fiber-optical method enabling simultaneous temperature measurements over long distances. Electrical resistance heating of the metallic components of the fiber-optic cable provides information on the thermal characteristics of the cable's environment, providing valuable insight into processes occurring in the surrounding medium, such as groundwater-surface water interactions, dam stability or soil moisture. Until now, heated applications required direct handling of the DTS instrument by a researcher, rendering long-term investigations in remote areas impractical due to the often difficult and time-consuming access to the field site. Remote control and automation of the DTS instrument and heating processes, however, resolve the issue with difficult access. The data can also be remotely accessed and stored on a central database. The power supply can be grid independent, although significant infrastructure investment is required here due to high power consumption during heated applications. Solar energy must be sufficient even in worst case scenarios, e.g. during long periods of intense cloud cover, to prevent system failure due to energy shortage. In combination with storage batteries and a low heating frequency, e.g. once per day or once per week (depending on the season and the solar radiation on site), issues of high power consumption may be resolved. Safety regulations dictate adequate shielding and ground-fault protection, to safeguard animals and humans from electricity and laser sources. In this paper the autonomous DTS system is presented to allow research with heated applications of DTS in remote areas for long-term investigations of temperature distributions in the environment.

  5. Highly entangled photons and rapidly responding polarization qubit phase gates in a room-temperature active Raman gain medium

    SciTech Connect

    Hang Chao; Huang Guoxiang

    2010-11-15

    We present a scheme for obtaining entangled photons and quantum phase gates in a room-temperature four-state tripod-type atomic system with two-mode active Raman gain (ARG). We analyze the linear and nonlinear optical responses of this ARG system and show that the scheme is fundamentally different from those based on electromagnetically induced transparency and hence can avoid significant probe-field absorption as well as a temperature-related Doppler effect. We demonstrate that highly entangled photon pairs can be produced and rapidly responding polarization qubit phase gates can be constructed based on the unique features of the enhanced cross-phase-modulation and superluminal probe-field propagation of the system.

  6. Recording and reading temperature tolerance in holographic data storage, in relation to the anisotropic thermal expansion of a photopolymer medium.

    PubMed

    Tanaka, Tomiji

    2009-08-01

    In holographic data storage, it is difficult to retrieve data if the temperature difference between recording and reading exceeds 2 K. To widen this tolerance, a compensation method--adjusting the wavelengths and incident directions of the recording and reading beams--has been proposed. In this paper, for the first time, a method for calculating the recording and reading temperature tolerance using this compensation is introduced. To widen the narrow tolerance, typically +/- 10 K, it is effective to increase the coefficient of thermal expansion (CTE) of the substrate or decrease the CTE of the photopolymer. Although reducing the Numerical aperture of the objective lens is also effective, it degrades the recording density. PMID:19654823

  7. High Temperature Wireless Communication And Electronics For Harsh Environment Applications

    NASA Technical Reports Server (NTRS)

    Hunter, G. W.; Neudeck, P. G.; Beheim, G. M.; Ponchak, G. E.; Chen, L.-Y

    2007-01-01

    In order for future aerospace propulsion systems to meet the increasing requirements for decreased maintenance, improved capability, and increased safety, the inclusion of intelligence into the propulsion system design and operation becomes necessary. These propulsion systems will have to incorporate technology that will monitor propulsion component conditions, analyze the incoming data, and modify operating parameters to optimize propulsion system operations. This implies the development of sensors, actuators, and electronics, with associated packaging, that will be able to operate under the harsh environments present in an engine. However, given the harsh environments inherent in propulsion systems, the development of engine-compatible electronics and sensors is not straightforward. The ability of a sensor system to operate in a given environment often depends as much on the technologies supporting the sensor element as the element itself. If the supporting technology cannot handle the application, then no matter how good the sensor is itself, the sensor system will fail. An example is high temperature environments where supporting technologies are often not capable of operation in engine conditions. Further, for every sensor going into an engine environment, i.e., for every new piece of hardware that improves the in-situ intelligence of the components, communication wires almost always must follow. The communication wires may be within or between parts, or from the engine to the controller. As more hardware is added, more wires, weight, complexity, and potential for unreliability is also introduced. Thus, wireless communication combined with in-situ processing of data would significantly improve the ability to include sensors into high temperature systems and thus lead toward more intelligent engine systems. NASA Glenn Research Center (GRC) is presently leading the development of electronics, communication systems, and sensors capable of prolonged stable

  8. Metabolic engineering for microbial production and applications of copolyesters consisting of 3-hydroxybutyrate and medium-chain-length 3-hydroxyalkanoates.

    PubMed

    Zou, Xiang Hui; Chen, Guo-Qiang

    2007-02-12

    Poly(hydroxyalkanoate)s (PHAs) are a class of microbially synthesized polyesters that combine biological properties, such as biocompatibility and biodegradability, and non-bioproperties such as thermoprocessability, piezoelectricity, and nonlinear optical activity. PHA monomer structures and their contents strongly affect the PHA properties. Using metabolic engineering approaches, PHA structures and contents can be manipulated to achieve controllable monomer and PHA cellular contents. This paper focuses on metabolic engineering methods to produce PHA consisting of 3-hydroxybutyrate (3HB) and medium-chain-length 3-hydroxyalkanoates (3HA) in recombinant microbial systems. This type of copolyester has mechanical and thermal properties similar to conventional plastics such as poly(propylene) and poly(ethylene terephthalate) (PET). In addition, pathways containing engineered PHA synthases have proven to be useful for enhanced PHA production with adjustable PHA monomers and contents. The applications of PHA as implant biomaterials are briefly discussed here. In the very near term, metabolic engineering will help solve many problems in promoting PHA as a new type of plastic material for many applications. PMID:17295404

  9. Second-generation functionalized medium-chain-length polyhydroxyalkanoates: the gateway to high-value bioplastic applications.

    PubMed

    Tortajada, Marta; da Silva, Luiziana Ferreira; Prieto, María Auxiliadora

    2013-03-01

    Polyhydroxyalkanoates (PHAs) are biodegradable biocompatible polyesters, which accumulate as granules in the cytoplasm of many bacteria under unbalanced growth conditions. Medium-chain-length PHAs (mcl-PHAs), characterized by C6-C14 branched monomer chains and typically produced by Pseudomonas species, are promising thermoelastomers, as they can be further modified by introducing functional groups in the side chains. Functionalized PHAs are obtained either by feeding structurally related substrates processed through the beta-oxidation pathway, or using specific strains able to transform sugars or glycerol into unsaturated PHA by de novo fatty-acid biosynthesis. Functionalized mcl-PHAs provide modified mechanical and thermal properties, and consequently have new processing requirements and highly diverse potential applications in emergent fields such as biomedicine. However, process development and sample availability are limited due to the toxicity of some precursors and still low productivity, which hinder investigation. Conversely, improved mutant strains designed through systems biology approaches and cofeeding with low-cost substrates may contribute to the widespread application of these biopolymers. This review focuses on recent developments in the production of functionalized mcl-PHAs, placing particular emphasis on strain and bioprocess design for cost-effective production. PMID:24151777

  10. Non-graphite crucible for high temperature applications

    DOEpatents

    Holcombe, C.E.; Pfeiler, W.A.

    1994-08-02

    A multi-piece crucible for high temperature applications comprises a tubular side wall member having a lip on the inside surface and a bottom member or members forming a container for containing a melt of a material during a high temperature melt-casting operations. The multi-piece design prevents cracking of the crucible or leakage of the melt from the crucible during the melt-casting operation. The lip of the tubular member supports the bottom member. The contacting surfaces where the lip of the tubular side wall member contacts the bottom member of the multi-piece crucible contains a ceramic sealing material. The ceramic sealing material forms a seal sufficient to prevent the melt of the material from leaking out of the multi-piece crucible during the melt-casting process. The multi-piece crucible is made of a material which is chemically inert to the melt and has structural integrity at the melting point temperature of the melt, or of a material coated with such a material. 6 figs.

  11. Non-graphite crucible for high temperature applications

    DOEpatents

    Holcombe, Cressie E.; Pfeiler, William A.

    1994-01-01

    A multi-piece crucible for high temperature applications comprises a tubular side wall member having a lip on the inside surface and a bottom member or members forming a container for containing a melt of a material during a high temperature melt-casting operations. The multi-piece design prevents cracking of the crucible or leakage of the melt from the crucible during the melt-casting operation. The lip of the tubular member supports the bottom member. The contacting surfaces where the lip of the tubular side wall member contacts the bottom member of the multi-piece crucible contains a ceramic sealing material. The ceramic sealing material forms a seal sufficient to prevent the melt of the material from leaking out of the multi-piece crucible during the melt-casting process. The multi-piece crucible is made of a material which is chemically inert to the melt and has structural integrity at the melting point temperature of the melt, or of a material coated with such a material.

  12. Trajectory optimization study of a lifting body re-entry vehicle for medium to intermediate range applications

    NASA Astrophysics Data System (ADS)

    Rizvi, S. Tauqeer ul Islam; Linshu, He; ur Rehman, Tawfiq; Rafique, Amer Farhan

    2012-11-01

    A numerical optimization study of lifting body re-entry vehicles is presented for nominal as well as shallow entry conditions for Medium and Intermediate Range applications. Due to the stringent requirement of a high degree of accuracy for conventional vehicles, lifting re-entry can be used to attain the impact at the desired terminal flight path angle and speed and thus can potentially improve accuracy of the re-entry vehicle. The re-entry of a medium range and intermediate range vehicles is characterized by very high negative flight path angle and low re-entry speed as compared to a maneuverable re-entry vehicle or a common aero vehicle intended for an intercontinental range. Highly negative flight path angles at the re-entry impose high dynamic pressure as well as heat loads on the vehicle. The trajectory studies are carried out to maximize the cross range of the re-entry vehicle while imposing a maximum dynamic pressure constraint of 350 KPa with a 3 MW/m2 heat rate limit. The maximum normal acceleration and the total heat load experienced by the vehicle at the stagnation point during the maneuver have been computed for the vehicle for possible future conceptual design studies. It has been found that cross range capability of up to 35 km can be achieved with a lifting-body design within the heat rate and the dynamic pressure boundary at normal entry conditions. For shallow entry angle of -20 degree and intermediate ranges a cross range capability of up to 250 km can be attained for a lifting body design with less than 10 percent loss in overall range. The normal acceleration also remains within limits. The lifting-body results have also been compared with wing-body results at shallow entry condition. An hp-adaptive pseudo-spectral method has been used for constrained trajectory optimization.

  13. Modelling of effects of water activity and temperature on germination and growth of ochratoxigenic isolates of Aspergillus ochraceus on a green coffee-based medium.

    PubMed

    Pardo, E; Ramos, A J; Sanchis, V; Marín, S

    2005-01-15

    Influence of water activity (0.75-0.99 a(w)) and temperature (10, 20 and 30 degrees C) on germination and mycelial growth on green coffee extract agar medium of three ochratoxigenic isolates of Aspergillus ochraceus was studied. Optimal conditions for germination and growth were observed at 0.95-0.99 a(w) and 20-30 degrees C for the three isolates. Minimum a(w) level for germination was 0.80, and 0.85 for mycelial growth. At marginal a(w) and temperature levels assayed, the lag phases prior to germination increased and the growth rates showed a significant decrease in comparison with the optimal conditions. Data were modelled by a multiple linear regression (MLR) and response surface models were obtained. Germination and growth of A. ochraceus in green coffee beans could be prevented or at least inhibited to some extent by minimising the time that coffee beans are exposed to temperature and humidity conditions near to the optimum during processing and storage. This could be an empirical approach to predict the effects of water activity and temperature conditions on the development of ochratoxigenic isolates of A. ochraceus during handling and storage of green coffee. PMID:15617796

  14. Partially sulfated lime-fly ash sorbents activated by water or steam for SO{sub 2} removal at a medium temperature

    SciTech Connect

    Liming Shi; Xuchang Xu

    2005-12-01

    Laboratory experiments were conducted to investigate the reactivity of partially sulfated lime-fly ash sorbents activated by water or steam for SO{sub 2} removal. Sulfation tests were performed at 550{sup o}C using a fixed bed reactor under conditions simulating economizer zone injection flue gas desulfurization. Activation experiments were conducted with water or steam using a range of temperatures between 100 and 550{sup o}C. The results showed that the reactivity of the sorbents was closely related to the content of Ca(OH){sub 2} formed in the activation process, which varied with the water or steam temperature. The sulfur dioxide capture capacity of Ca(OH){sub 2} in the sorbent is higher than that of CaO at a medium temperature. Water or steam temperatures in the range of 100-200{sup o}C are favorable to the formation of Ca(OH){sub 2} from CaO. 15 refs., 8 figs., 2 tabs.

  15. Exceptional damage-tolerance of a medium-entropy alloy CrCoNi at cryogenic temperatures

    DOE PAGESBeta

    Gludovatz, Bernd; Hohenwarter, Anton; Thurston, Keli V. S.; Bei, Hongbin; Wu, Zhenggang; George, Easo P.; Ritchie, Robert O.

    2016-02-02

    The high-entropy alloys are an intriguing new class of metallic materials that derive their properties not from a single dominant constituent, such as iron in steels, nor from the presence of a second phase, such as in nickel-base superalloys, but rather comprise multi-element systems that crystallize as a single phase, despite containing high concentrations (~20 at.%) of five or more elements with different crystal structures. Indeed, we have recently reported on one such single-phase high-entropy alloy, NiCoCrFeMn, which displays exceptional strength and toughness at cryogenic temperatures. Here which displays unprecedented strength-toughness properties that exceed those of all high-entropy alloys andmore » most multi-phase alloys. With roomtemperature tensile strengths of almost 1 GPa and KJIc fracture-toughness values above 200 MPa.m 1/2 (with crack-growth toughnesses exceeding 300 MPa.m 1/2), the strength, ductility and toughness of the NiCoCr alloy actually improve at cryogenic temperatures to unprecedented levels of strengths above 1.3 GPa, failure strains up to 90% and KJIc values of 275 MPa.m 1/2 (with crackgrowth toughnesses above 400 MPa.m 1/2). These properties appear to result from continuous steady strain hardening, which acts to suppress plastic instability, resulting from pronounced dislocation activity and deformation-induced nano-twinning.« less

  16. Enabling high-temperature nanophotonics for energy applications

    PubMed Central

    Yeng, Yi Xiang; Ghebrebrhan, Michael; Bermel, Peter; Chan, Walker R.; Joannopoulos, John D.; Soljačić, Marin; Celanovic, Ivan

    2012-01-01

    The nascent field of high-temperature nanophotonics could potentially enable many important solid-state energy conversion applications, such as thermophotovoltaic energy generation, selective solar absorption, and selective emission of light. However, special challenges arise when trying to design nanophotonic materials with precisely tailored optical properties that can operate at high-temperatures (> 1,100 K). These include proper material selection and purity to prevent melting, evaporation, or chemical reactions; severe minimization of any material interfaces to prevent thermomechanical problems such as delamination; robust performance in the presence of surface diffusion; and long-range geometric precision over large areas with severe minimization of very small feature sizes to maintain structural stability. Here we report an approach for high-temperature nanophotonics that surmounts all of these difficulties. It consists of an analytical and computationally guided design involving high-purity tungsten in a precisely fabricated photonic crystal slab geometry (specifically chosen to eliminate interfaces arising from layer-by-layer fabrication) optimized for high performance and robustness in the presence of roughness, fabrication errors, and surface diffusion. It offers near-ultimate short-wavelength emittance and low, ultra-broadband long-wavelength emittance, along with a sharp cutoff offering 4∶1 emittance contrast over 10% wavelength separation. This is achieved via Q-matching, whereby the absorptive and radiative rates of the photonic crystal’s cavity resonances are matched. Strong angular emission selectivity is also observed, with short-wavelength emission suppressed by 50% at 75° compared to normal incidence. Finally, a precise high-temperature measurement technique is developed to confirm that emission at 1,225 K can be primarily confined to wavelengths shorter than the cutoff wavelength. PMID:22308448

  17. Alcohol from whey permeate: strain selection, temperature, and medium optimization. [Candida pseudotropicalis, Kluyveromyces fragilis, and K. lactis

    SciTech Connect

    Vienne, P.; Von Stockar, U.

    1983-01-01

    A comparative study of shaken flask cultures of some yeast strains capable of fermenting lactose showed no significant differences in alcohol yield among the four best strains. Use of whey permeate concentrated three times did not affect the yields. An optimal growth temperature of 38/sup 0/C was determined for K. fragilis NRRL 665. Elemental analysis of both the permeate and the dry cell mass of two strains indicated the possibility of a stoichiometric limitation by nitrogen. Batch cultures in laboratory fermentors confirmed this finding and revealed in addition the presence of a limitation due to growth factors. Both types of limitations could be overcome by adding yeast extract. The maximum productivity of continuous cultures could thus be improved to 5.1 g/l-h. The maximum specific growth rate was of the order of 0.310 h/sup -1/. 15 references, 10 figures, 9 tables.

  18. Self potential generated by two-phase flow in a porous medium: Experimental study and volcanological applications

    SciTech Connect

    Antraygues, P.; Aubert, M.

    1993-12-01

    In order to characterize the relationships between self-potential generation and hydrothermal convection, laboratory measurements of electric potential and temperature are made along a vertical cylindrical column of porous material where a two-phase flow (wet steam) occurs. For steady state convection, the vertical distributions of vapor and water flow rates are calculated from thermal balance. At the initiation of convection, a positive electrical charge flux is related to the convective front. For isothermal and steady state columns, a positive electric potential gradient is observed along the vapor flow direction. These electric potentials are mainly a function of the vapor flow rates and of the medium permeability. A sudden and large increase in the vapor flow rate and in the volume fraction of vapor can induce a large and long-lived increase in the potential differences along the vapor flow direction. An electrokinetic effect related to the saturated vapor flow is the best candidate for this electric potential generation. The experimental resutls obtained in the present study are applied to self-potential generation in rising two-phase convective cells on active volcanoes. The observed positive self-potential anomalies close to active fissures depend on the electrical charge flux related to the upward saturated vapor flow. These results also demonstrate the value of self-potential monitoring in the early stages preceding a volcanic eruption.

  19. NASA PS400: A New Temperature Solid Lubricant Coating for High Temperature Wear Applications

    NASA Technical Reports Server (NTRS)

    DellaCorte, C.; Edmonds, B. J.

    2009-01-01

    A new solid lubricant coating, NASA PS400, has been developed for high temperature tribological applications. This plasma sprayed coating is a variant of the patented PS304 coating and has been formulated to provide higher density, smoother surface finish and better dimensional stability than PS304. PS400 is comprised of a nickel-molybdenum binder that provides strength, creep resistance and extreme oxidative and dimensional stability. Chromium oxide, silver and barium-calcium fluoride eutectic are added to the binder to form PS400.Tribological properties were evaluated with a pin-on-disk test rig in sliding contact to 650 C. Coating material samples were exposed to air, argon and vacuum at 760 C followed by cross section microscopic analysis to assess microstructure stability. Oil-Free microturbine engine hot section foil bearing tests were undertaken to assess PS400 s suitability for hot foil gas bearing applications. The preliminary results indicate that PS400 exhibits tribological characteristics comparable to the PS304 coating but with enhanced creep resistance and dimensional stability suitable for demanding, dynamic applications.

  20. New Optimal Sensor Suite for Ultrahigh Temperature Fossil Fuel Applications

    SciTech Connect

    John Coggin; Jonas Ivasauskas; Russell G. May; Michael B. Miller; Rena Wilson

    2006-09-30

    Accomplishments during Phase II of a program to develop and demonstrate photonic sensor technology for the instrumentation of advanced powerplants are described. The goal of this project is the research and development of advanced, robust photonic sensors based on improved sapphire optical waveguides, and the identification and demonstration of applications of the new sensors in advanced fossil fuel power plants, where the new technology will contribute to improvements in process control and monitoring. During this program work period, major progress has been experienced in the development of the sensor hardware, and the planning of the system installation and operation. The major focus of the next work period will be the installation of sensors in the Hamilton, Ohio power plant, and demonstration of high-temperature strain gages during mechanical testing of SOFC components.

  1. High temperature solder alloys for underhood applications. Progress report

    SciTech Connect

    Drewien, C.A.; Yost, F.G.; Sackinger, S.; Kern, J.; Weiser, M.W.

    1995-02-01

    Under a cooperative research and development agreement with General Motors Corporation, lead-free solder systems including the flux, metallization, and solder are being developed for high temperature, underhood applications. Six tin-rich solders, five silver-rich metallizations, and four fluxes were screened using an experimental matrix whereby every combination was used to make sessile drops via hot plate or Heller oven processing. The contact angle, sessile drop appearance, and in some instances the microstructure was evaluated to determine combinations that would yield contact angles of less than 30{degrees}, well-formed sessile drops, and fine, uniform microstructures. Four solders, one metallization, and one flux were selected and will be used for further aging and mechanical property studies.

  2. Developments in TurboBrayton Technology for Low Temperature Applications

    NASA Technical Reports Server (NTRS)

    Swift, W. L.; Zagarola, M. V.; Nellis, G. F.; McCormick, J. A.; Gibbon, Judy

    1999-01-01

    A single stage reverse Brayton cryocooler using miniature high-speed turbomachines recently completed a successful space shuttle test flight demonstrating its capabilities for use in cooling the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space Telescope (HST). The NICMOS CryoCooler (NCC) is designed for a cooling load of about 8 W at 65 K, and comprises a closed loop cryocooler coupled to an independent cryogenic circulating loop. Future space applications involve instruments that will require 5 mW to 200 mW of cooling at temperatures between 4 K and 10 K. This paper discusses the extension of Turbo-Brayton technology to meet these requirements.

  3. Advanced materials for high-temperature solid electrolyte applications

    SciTech Connect

    Bates, J.L.; Chick, L.A.; Weber, W.J.; Youngblood, G.E.

    1990-05-01

    Advanced materials for use as electrodes, interconnections, and electrolytes in high-temperature electrochemical applications are under investigation. The air sinterability of La{sub 1-x}Sr{sub x}CrO{sub 3} is highly dependent upon a synergistic relationship between the (La + Sr)/Cr ratio, cation volatility, and second phase formation and transformation. Electrical conductivity in the ZrO{sub 2}--Y{sub 2}O{sub 3}--CeO{sub 2} and ZrO{sub 2}--Y{sub 2}O{sub 3}--TiO{sub 2} systems is highly dependent on composition and atmosphere. The electrochemical processes that occur at the solid-solid-gas interfaces in La(Sr)MnO{sub 3}/ZrO{sub 2}(Y{sub 2}O{sub 3}) have been studied using an unbonded interface cell and impedance spectroscopy. 6 refs., 7 figs.

  4. Amorphous metallizations for high-temperature semiconductor device applications

    NASA Technical Reports Server (NTRS)

    Wiley, J. D.; Perepezko, J. H.; Nordman, J. E.; Kang-Jin, G.

    1981-01-01

    The initial results of work on a class of semiconductor metallizations which appear to hold promise as primary metallizations and diffusion barriers for high temperature device applications are presented. These metallizations consist of sputter-deposited films of high T sub g amorphous-metal alloys which (primarily because of the absence of grain boundaries) exhibit exceptionally good corrosion-resistance and low diffusion coefficients. Amorphous films of the alloys Ni-Nb, Ni-Mo, W-Si, and Mo-Si were deposited on Si, GaAs, GaP, and various insulating substrates. The films adhere extremely well to the substrates and remain amorphous during thermal cycling to at least 500 C. Rutherford backscattering and Auger electron spectroscopy measurements indicate atomic diffussivities in the 10 to the -19th power sq cm/S range at 450 C.

  5. High-temperature process heat applications with an HTGR

    SciTech Connect

    Quade, R.N.; Vrable, D.L.

    1980-04-01

    An 842-MW(t) HTGR-process heat (HTGR-PH) design and several synfuels and energy transport processes to which it could be coupled are described. As in other HTGR designs, the HTGR-PH has its entire primary coolant system contained in a prestressed concrete reactor vessel (PCRV) which provides the necessary biological shielding and pressure containment. The high-temperature nuclear thermal energy is transported to the externally located process plant by a secondary helium transport loop. With a capability to produce hot helium in the secondary loop at 800/sup 0/C (1472/sup 0/F) with current designs and 900/sup 0/C (1652/sup 0/F) with advanced designs, a large number of process heat applications are potentially available. Studies have been performed for coal liquefaction and gasification using nuclear heat.

  6. Type T reference function suitability for low temperature applications

    NASA Astrophysics Data System (ADS)

    Dowell, D.

    2013-09-01

    Type T thermocouples are commonly used in industrial measurement applications due to their accuracy relative to other thermocouple types, low cost, and the ready availability of measurement equipment. Type T thermocouples are very effective when used in differential measurements, as there is no cold junction compensation necessary for the connections to the measurement equipment. Type T's published accuracy specifications result in its frequent use in low temperature applications. An examination of over 328 samples from a number of manufacturers has been completed for this investigation. Samples were compared to a Standard Platinum Resistance Thermometer (SPRT) at the LN2 boiling point along with four other standardized measurement points using a characterized ice point reference, low-thermal EMF scanner and an 8.5 digit multimeter, and the data compiled and analyzed. The test points were approximately -196 °C, -75 °C, 0 °C, +100 °C, and +200 °C. These data show an anomaly in the conformance to the reference functions where the reference functions meet at 0 °C. Additionally, in the temperature region between -100 °C to -200 °C, a positive offset of up to 5.4 °C exists between the reference function equations published in the ASTM E230-06 for the nitrogen point and the measured response of the actual wire. This paper will examine the historical and technological reasons for this anomaly in the both the ASTM and IEC reference functions. At the request of the author and the Proceedings Editor the above article has been replaced with a corrected version. The original PDF file supplied to AIP Publishing contained several figures with missing information/characters—caused by processes used to generate the PDF file. All figures were affected by this error. The article has been replaced and these figures now display correctly. The corrected article was published on 7 November 2013.

  7. Pyrolyzed feather fibers for adsorbent and high temperature applications

    NASA Astrophysics Data System (ADS)

    Senoz, Erman

    used in applications such as adsorption, storage, and separation of small gas molecules. The maximum excess H2 storage capacity was 1.5 wt% at 77 K and at pressures below 2 MPa. The notable H2 adsorption of PCFF below 1 MPa can be justified by the abundance of microporosity and the nanopores available for H2 penetration. In the second step of the pyrolysis the protein matrix went through a series of transformations including cyclization and aromatization reactions above the melting point. A partially cyclic carbon-nitrogen framework (carbon/nitrogen ratio=2.38) supported by double and triple bonds and oxygen functionalities is the suggested structural model for the PCFF. The useful fibers and adsorbents produced from CFF in this dissertation can encourage researchers to use high temperature heat treatments on keratin-based fibers. Also, the identified pyrolysis mechanisms can serve as a guide for producing materials with desired properties from protein-based materials, particularly in textile, high performance composite and catalyst industries.

  8. Catalytic dehydrogenation of propane by carbon dioxide: a medium-temperature thermochemical process for carbon dioxide utilisation.

    PubMed

    Du, X; Yao, B; Gonzalez-Cortes, S; Kuznetsov, V L; AlMegren, Hamid; Xiao, T; Edwards, P P

    2015-01-01

    The dehydrogenation of C3H8 in the presence of CO2 is an attractive catalytic route for C3H6 production. In studying the various possibilities to utilise CO2 to convert hydrocarbons using the sustainable energy source of solar thermal energy, thermodynamic calculations were carried out for the dehydrogenation of C3H8 using CO2for the process operating in the temperature range of 300-500 °C. Importantly, the results highlight the enhanced potential of C3H8 as compared to its lighter and heavier homologues (C2H6 and C4H10, respectively). To be utilised in this CO2 utilisation reaction the Gibbs free energy (ΔrGθm) of each reaction in the modelled, complete reacting system of the dehydrogenation of C3H8 in the presence of CO2 also indicate that further cracking of C3H6 will affect the ultimate yield and selectivity of the final products. In a parallel experimental study, catalytic tests of the dehydrogenation of C3H8 in the presence of CO2 over 5 wt%-Cr2O3/ZrO2 catalysts operating at 500 °C, atmospheric pressure, and for various C3H8 partial pressures and various overall GHSV (Gas Hourly Space Velocity) values. The results showed that an increase in the C3H8 partial pressure produced an inhibition of C3H8 conversion but, importantly, a promising enhancement of C3H6 selectivity. This phenomenon can be attributed to competitive adsorption on the catalyst between the generated C3H6 and inactivated C3H8, which inhibits any further cracking effect on C3H6 to produce by-products. As a comparison, the increase of the overall GHSV can also decrease the C3H8 conversion to a similar extent, but the further cracking of C3H6 cannot be limited. PMID:26392020

  9. High Temperature Gas Reactors: Assessment of Applicable Codes and Standards

    SciTech Connect

    McDowell, Bruce K.; Nickolaus, James R.; Mitchell, Mark R.; Swearingen, Gary L.; Pugh, Ray

    2011-10-31

    Current interest expressed by industry in HTGR plants, particularly modular plants with power up to about 600 MW(e) per unit, has prompted NRC to task PNNL with assessing the currently available literature related to codes and standards applicable to HTGR plants, the operating history of past and present HTGR plants, and with evaluating the proposed designs of RPV and associated piping for future plants. Considering these topics in the order they are arranged in the text, first the operational histories of five shut-down and two currently operating HTGR plants are reviewed, leading the authors to conclude that while small, simple prototype HTGR plants operated reliably, some of the larger plants, particularly Fort St. Vrain, had poor availability. Safety and radiological performance of these plants has been considerably better than LWR plants. Petroleum processing plants provide some applicable experience with materials similar to those proposed for HTGR piping and vessels. At least one currently operating plant - HTR-10 - has performed and documented a leak before break analysis that appears to be applicable to proposed future US HTGR designs. Current codes and standards cover some HTGR materials, but not all materials are covered to the high temperatures envisioned for HTGR use. Codes and standards, particularly ASME Codes, are under development for proposed future US HTGR designs. A 'roadmap' document has been prepared for ASME Code development; a new subsection to section III of the ASME Code, ASME BPVC III-5, is scheduled to be published in October 2011. The question of terminology for the cross-duct structure between the RPV and power conversion vessel is discussed, considering the differences in regulatory requirements that apply depending on whether this structure is designated as a 'vessel' or as a 'pipe'. We conclude that designing this component as a 'pipe' is the more appropriate choice, but that the ASME BPVC allows the owner of the facility to select

  10. Bacterial Community Dynamics During the Application of a Myxococcus xanthus-Inoculated Culture Medium Used for Consolidation of Ornamental Limestone

    PubMed Central

    Jimenez-Lopez, Concepcion; Sterflinger, Katja; Ettenauer, Jörg; Jroundi, Fadwa; Fernandez-Vivas, Antonia; Gonzalez-Muñoz, Maria Teresa

    2010-01-01

    In this study, we investigated under laboratory conditions the bacterial communities inhabiting quarry and decayed ornamental carbonate stones before and after the application of a Myxococcus xanthus-inoculated culture medium used for consolidation of the stones. The dynamics of the community structure and the prevalence of the inoculated bacterium, M. xanthus, were monitored during the time course of the consolidation treatment (30 days). For this purpose, we selected a molecular strategy combining fingerprinting by denaturing gradient gel electrophoresis (DGGE) with the screening of eubacterial 16S rDNA clone libraries by DGGE and sequencing. Quantification of the inoculated strain was performed by quantitative real-time PCR (qPCR) using M. xanthus-specific primers designed in this work. Results derived from DGGE and sequencing analysis showed that, irrespective of the origin of the stone, the same carbonatogenic microorganisms were activated by the application of a M. xanthus culture. Those microorganisms were Pseudomonas sp., Bacillus sp., and Brevibacillus sp. The monitoring of M. xanthus in the culture media of treated stones during the time course experiment showed disparate results depending on the applied technique. By culture-dependent methods, the detection of this bacterium was only possible in the first day of the treatment, showing the limitation of these conventional techniques. By PCR-DGGE analysis, M. xanthus was detected during the first 3–6 days of the experiment. At this time, the population of this bacterium in the culture media varied between 108–106 cells ml−1, as showed by qPCR analyses. Thereafter, DGGE analyses showed to be not suitable for the detection of M. xanthus in a mixed culture. Nevertheless, qPCR analysis using specific primers for M. xanthus showed to be a more sensitive technique for the detection of this bacterium, revealing a population of 104 cells ml−1 in the culture media of both treated stones at the end of

  11. Low temperature CFB gasifier conceptual ideas and applications

    SciTech Connect

    Stoholm, P.; Fock, M.W.; Henriksen, U.

    1999-07-01

    A novel Circulating Fluidized Bed (CFB) gasification process for volatile fuels such as biomass and many waste materials are described. The fuel is pyrolyzed at e.g. 550 C in the CFB reaction chamber and the char residue is converted at e.g. 650 C in a separate Bubbling Fluidized Bed (BFB) char gasification chamber located in the particle recirculation path. Due to the tendency for char particles to segregate to the upper part of the BFB they achieve a high retention time in the slowly fluidized BFB by recirculating mainly inert particles from the bottom. In a simple version of the process essentially all of the air is added to the bottom of the BFB and the produced char gas serves as fluidizing gas in the CFB reaction chamber. This way the product gas leaving the CFB reaction chamber obtains a higher heating value at around 11 MJ/Nm{sup 3} when using a biomass fuel with around 15% moisture. In combination with the low process temperature, and not needing building height for char conversion in the CFB reaction chamber, this means that the CFB reactor and off-gas system becomes very compact. The low temperatures also means that agglomeration can be avoided even when using fuels such as unweathered straw with a high content of alkaline and chlorine. Furthermore, the alkaline and chlorine in the raw gas will mainly be in the solid state meaning that a high retention can be obtained simply by efficient particle separation. The paper mentions a number of possible applications for the gasifier including as an example a simple and compact system for co-firing biomass and waste at power plants.

  12. Niobium Oxide-Metal Based Seals for High Temperature Applications

    SciTech Connect

    Ivar Reimanis

    2006-08-14

    The present final report describes technical progress made in regards to evaluating niobium oxide/alumina as a high temperature seal material. Fabrication and characterization of specimens comprising niobium oxide and alumina composites of various compositions was performed. The goal was to identify regions where a glass formed. There were no experimental conditions where a glassy phase was unequivocally identified. However, the results led to the formation of an interesting class of fibrous composites which may have applications where high compliance and high toughness are needed. It is clear that vapor phase sintering is an active mass transport mechanism in Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3} composites (Figure 1), and it may be possible to design porous materials by utilizing vapor phase sintering. The compositions evaluated in the present work are 52, 60, 73, 82 and 95 mol. % Nb{sub 2}O{sub 5} with the remainder Al{sub 2}O{sub 3}. These were chosen so that some eutectic composition was present during cooling, in an attempt to encourage glass formation. However, the presence of large, elongated crystals, both in the slow cool and the quench experiments indicates that the driving force for crystallization is very high. Several joints were formed between high purity alumina with two compositions (60 and 82 mol. %) forming the joint. These were created by grinding and polishing alumina surfaces and stacking them end-to-end with the powdered Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3} material in between. Joining was accomplished in air at temperatures between 1400 C and 1450 C. The joints failed during subsequent machining for strength bars, indicating low strength. It may be possible to use the compositions evaluated here as a joint material, but it seems unlikely that a glassy phase could be produced while joining.

  13. Production of gymnemic acid depends on medium, explants, PGRs, color lights, temperature, photoperiod, and sucrose sources in batch culture of Gymnema sylvestre.

    PubMed

    Ahmed, A Bakrudeen Ali; Rao, A S; Rao, M V; Taha, Rosna Mat

    2012-01-01

    Gymnema sylvestre (R.Br.) is an important diabetic medicinal plant which yields pharmaceutically active compounds called gymnemic acid (GA). The present study describes callus induction and the subsequent batch culture optimization and GA quantification determined by linearity, precision, accuracy, and recovery. Best callus induction of GA was noticed in MS medium combined with 2,4-D (1.5 mg/L) and KN (0.5 mg/L). Evaluation and isolation of GA from the calluses derived from different plant parts, namely, leaf, stem and petioles have been done in the present case for the first time. Factors such as light, temperature, sucrose, and photoperiod were studied to observe their effect on GA production. Temperature conditions completely inhibited GA production. Out of the different sucrose concentrations tested, the highest yield (35.4 mg/g d.w) was found at 5% sucrose followed by 12 h photoperiod (26.86 mg/g d.w). Maximum GA production (58.28 mg/g d.w) was observed in blue light. The results showed that physical and chemical factors greatly influence the production of GA in callus cultures of G. sylvestre. The factors optimized for in vitro production of GA during the present study can successfully be employed for their large-scale production in bioreactors. PMID:22629221

  14. Production of Gymnemic Acid Depends on Medium, Explants, PGRs, Color Lights, Temperature, Photoperiod, and Sucrose Sources in Batch Culture of Gymnema sylvestre

    PubMed Central

    Ahmed, A. Bakrudeen Ali; Rao, A. S.; Rao, M. V.; Taha, Rosna Mat

    2012-01-01

    Gymnema sylvestre (R.Br.) is an important diabetic medicinal plant which yields pharmaceutically active compounds called gymnemic acid (GA). The present study describes callus induction and the subsequent batch culture optimization and GA quantification determined by linearity, precision, accuracy, and recovery. Best callus induction of GA was noticed in MS medium combined with 2,4-D (1.5 mg/L) and KN (0.5 mg/L). Evaluation and isolation of GA from the calluses derived from different plant parts, namely, leaf, stem and petioles have been done in the present case for the first time. Factors such as light, temperature, sucrose, and photoperiod were studied to observe their effect on GA production. Temperature conditions completely inhibited GA production. Out of the different sucrose concentrations tested, the highest yield (35.4 mg/g d.w) was found at 5% sucrose followed by 12 h photoperiod (26.86 mg/g d.w). Maximum GA production (58.28 mg/g d.w) was observed in blue light. The results showed that physical and chemical factors greatly influence the production of GA in callus cultures of G. sylvestre. The factors optimized for in vitro production of GA during the present study can successfully be employed for their large-scale production in bioreactors. PMID:22629221

  15. Application of statistical experimental design for optimisation of bioinsecticides production by sporeless Bacillus thuringiensis strain on cheap medium

    PubMed Central

    Ben Khedher, Saoussen; Jaoua, Samir; Zouari, Nabil

    2013-01-01

    In order to overproduce bioinsecticides production by a sporeless Bacillus thuringiensis strain, an optimal composition of a cheap medium was defined using a response surface methodology. In a first step, a Plackett-Burman design used to evaluate the effects of eight medium components on delta-endotoxin production showed that starch, soya bean and sodium chloride exhibited significant effects on bioinsecticides production. In a second step, these parameters were selected for further optimisation by central composite design. The obtained results revealed that the optimum culture medium for delta-endotoxin production consists of 30 g L−1 starch, 30 g L−1 soya bean and 9 g L−1 sodium chloride. When compared to the basal production medium, an improvement in delta-endotoxin production up to 50% was noted. Moreover, relative toxin yield of sporeless Bacillus thuringiensis S22 was improved markedly by using optimised cheap medium (148.5 mg delta-endotoxins per g starch) when compared to the yield obtained in the basal medium (94.46 mg delta-endotoxins per g starch). Therefore, the use of optimised culture cheap medium appeared to be a good alternative for a low cost production of sporeless Bacillus thuringiensis bioinsecticides at industrial scale which is of great importance in practical point of view. PMID:24516462

  16. Modelling of heat and mass transfer in a granular medium during high-temperature air drying. Effect of the internal gas pressure

    NASA Astrophysics Data System (ADS)

    Othmani, Hammouda; Hassini, Lamine; Lamloumi, Raja; El Cafsi, Mohamed Afif

    2016-02-01

    A comprehensive internal heat and water transfer model including the gas pressure effect has been proposed in order to improve the industrial high-temperature air drying of inserts made of agglomerated sand. In this model, the internal gas phase pressure effect was made perfectly explicit, by considering the liquid and vapour transfer by filtration and the liquid expulsion at the surface. Wet sand enclosed in a tight cylindrical glass bottle dried convectively at a high temperature was chosen as an application case. The model was validated on the basis of the experimental average water content and core temperature curves for drying trials at different operating conditions. The simulations of the spatio-temporal distribution of internal gas pressure were performed and interpreted in terms of product potential damage. Based on a compromise between the drying time and the pressure increase, a simple drying cycle was implemented in order to optimize the drying process.

  17. Room temperature molten salt electrolytes for photoelectrochemical applications

    SciTech Connect

    Rajeshwar, K.; DuBow, J.; Singh, P.

    1982-08-01

    Mixtures of aluminum chloride (AlCl/sub 3/) with triethylammonium chloride 1,6-ethyl lutidinium bromide (EtluBr), tert-butyl pyridinium bromide (BPBr), and dialkyl imidazolium chloride (R/sub 2/ImCl), in certain molar ratios yielded ionic liquids at room temperature which were studied with respect to their applicability as electrolytes in photoelectrochemical (PEC) cells. Background voltammograms were obtained for these electrolytes on carbon and n-GaAs electrodes. The anodic stability limit was found to be enhanced on n-GaAs relative to carbon in all cases. The cathodic decomposition potential of the electrolyte showed a smaller positive shift on n-GaAs with the exception of the 3:1 AlCl/sub 3/ BPBr electrolyte. The difference in electrolyte stability behavior on carbon and n-GaAs is interpreted in terms of carrier density effects. Cyclic voltammograms were compared on carbon in the various electrolytes for a model redox system comprising the ferrocene/ferricenium couple. The separation of the cathodic and anodic waves in all the cases was consistent with a quasi-reversible redox behavior--the most sluggish electron transfer being observed in the case of the 3:1 AlCl/sub 3/-BpBr electrolyte. Capacitance-voltage measurements were made on n-GaAs electrodes in contact with the various electrolytes. Flatband-potentials (V /SUB fb/) were deduced from these data using Mott-Schottky plots. The implications of this result for PEC applications and the role of specific ion adsorption of electrolyte species on the electrostatic aspects of the n-GaAs/molten salt electrolyte-interface are discussed with the aid of energy band diagrams.

  18. Downscaling MODIS Land Surface Temperature for Urban Public Health Applications

    NASA Technical Reports Server (NTRS)

    Al-Hamdan, Mohammad; Crosson, William; Estes, Maurice Jr.; Estes, Sue; Quattrochi, Dale; Johnson, Daniel

    2013-01-01

    This study is part of a project funded by the NASA Applied Sciences Public Health Program, which focuses on Earth science applications of remote sensing data for enhancing public health decision-making. Heat related death is currently the number one weather-related killer in the United States. Mortality from these events is expected to increase as a function of climate change. This activity sought to augment current Heat Watch/Warning Systems (HWWS) with NASA remotely sensed data, and models used in conjunction with socioeconomic and heatrelated mortality data. The current HWWS do not take into account intra-urban spatial variation in risk assessment. The purpose of this effort is to evaluate a potential method to improve spatial delineation of risk from extreme heat events in urban environments by integrating sociodemographic risk factors with estimates of land surface temperature (LST) derived from thermal remote sensing data. In order to further improve the consideration of intra-urban variations in risk from extreme heat, we also developed and evaluated a number of spatial statistical techniques for downscaling the 1-km daily MODerate-resolution Imaging Spectroradiometer (MODIS) LST data to 60 m using Landsat-derived LST data, which have finer spatial but coarser temporal resolution than MODIS. In this paper, we will present these techniques, which have been demonstrated and validated for Phoenix, AZ using data from the summers of 2000-2006.

  19. Development of high temperature superconductors for magnetic field applications

    NASA Astrophysics Data System (ADS)

    Larbalestier, D. C.

    The key requirement for magnetic field applications of high temperature superconductor (HTS) materials is to have conductors with high transport critical current density available for magnet builders. After 3 or 4 years of being without any such object, conductor makers have had recent success in producing simple conductor prototypes. These have permitted the construction of simple HTS magnets having self fields exceeding 1 tesla at 4K. Thus the scientific feasibility of making powerful HTS magnets has been demonstrated. Attention to the technological aspects of making HTS conductors for magnets with strong flux pinning and reduced superconducting granularity is now sensible and attractive. However, extrinsic defects such as filament sausaging, cracking, misaligned grains and other perturbation to long range current flow must be controlled at a low level if the benefit of intrinsic improvements to the critical current density is to be maintained in the conductor form. Due to the great complexity of the HTS materials, there is sometimes confusion as to whether a given sample has an intrinsically or extrinsically limited critical current density. Systematic microstructure variation experiments and resistive transition analysis are shown to be particularly helpful in this phase of conductor development.

  20. Space optical payloads, new application area for high temperature composites

    NASA Astrophysics Data System (ADS)

    Capdepuy, B.; Leleu, F.; Boursereau, F.; Parrot, P.; Bailly, B.; Riti, J. B.; Cornu, J. L.

    High temperature composites have been extensively developed in order to produce thermal protection systems of reusable re-entry vehicles and launchers. This development effort covers all aspects including sizing, design, manufacturing processes characterization, non destructive inspection, and all industrial facilities which have also been installed. Strong interest recently appeared for these materials to meet requirements for different space applications. In particularly, for more stringent optical payloads, new materials with high performance requirements have appeared. In the field of high dimensionally stable structures for telescopes, materials have to meet severe requirements, such as low coefficients of thermal expansion, good specific modulus, long-term stability (moisture and chemical insensitivity), etc. Carbon/carbon (C/C) composites can meet these specifications. To demonstrate this capability a structure has been designed, manufactured and will be submitted for complete testing (work supported by ESA/ESTEC). The main available results (part feasibility, characterizations, analysis and stability performance budgets) are presented. For future telescope mirrors, silicon carbide is already known as a good candidate. However, an innovative concept based on silicon carbide sandwich honeycomb technology, which allows optimized design, has been developed. The first characterization results and manufacturing capabilities are presented.

  1. Development of high temperature superconductors for magnetic field applications

    SciTech Connect

    Larbalestier, D.C.

    1991-12-31

    The key requirement for magnetic field applications of high temperature superconductor (HTS) materials is to have conductors with high transport critical current density available for magnet builders. After 3 or 4 years of being without any such object, conductor makers have had recent success in producing simple conductor prototypes. These have permitted the construction of simple HTS magnets having self fields exceeding 1 tesla at 4K. Thus the scientific feasibility of making powerful HTS magnets has been demonstrated. Attention to the technological aspects of making HTS conductors for magnets with strong flux pinning and reduced superconducting granularity is now sensible and attractive. However, extrinsic defects such as filament sausaging, cracking, misaligned grains and other perturbation to long range current flow must be controlled at a low level if the benefit of intrinsic improvements to the critical current density is to be maintained in the conductor form. Due to the great complexity of the HTS materials, there is sometimes confusion as to whether a given sample has an intrinsically or extrinsically limited critical current density. Systematic microstructure variation experiments and resistive transition analysis are shown to be particularly helpful in this phase of conductor development.

  2. Development of high temperature superconductors for magnetic field applications

    SciTech Connect

    Larbalestier, D.C.

    1991-01-01

    The key requirement for magnetic field applications of high temperature superconductor (HTS) materials is to have conductors with high transport critical current density available for magnet builders. After 3 or 4 years of being without any such object, conductor makers have had recent success in producing simple conductor prototypes. These have permitted the construction of simple HTS magnets having self fields exceeding 1 tesla at 4K. Thus the scientific feasibility of making powerful HTS magnets has been demonstrated. Attention to the technological aspects of making HTS conductors for magnets with strong flux pinning and reduced superconducting granularity is now sensible and attractive. However, extrinsic defects such as filament sausaging, cracking, misaligned grains and other perturbation to long range current flow must be controlled at a low level if the benefit of intrinsic improvements to the critical current density is to be maintained in the conductor form. Due to the great complexity of the HTS materials, there is sometimes confusion as to whether a given sample has an intrinsically or extrinsically limited critical current density. Systematic microstructure variation experiments and resistive transition analysis are shown to be particularly helpful in this phase of conductor development.

  3. Application of hard coatings to substrates at low temperatures

    NASA Technical Reports Server (NTRS)

    Sproul, William D.

    1993-01-01

    BIRL, the industrial research laboratory of Northwestern University, has conducted unique and innovative research, under sponsorship from the NASA Marshall Space Flight Center (MSFC), in the application of hard, wear resistant coatings to bearing steels using the high-rate reactive sputtering (HRRS) process that was pioneered by Dr. William Sproul, the principal investigator on this program. Prior to this program, Dr. Sproul had demonstrated that it is possible to apply hard coatings such as titanium nitride (TiN) to alloy steels at low temperatures via the HRRS process without changing the metallurgical properties of the steel. The NASA MSFC program at BIRL had the specific objectives to: apply TiN to 440C stainless steel without changing the metallurgical properties of the steel; prepare rolling contact fatigue (RCF) test samples coated with binary hard coatings of TiN, zirconium nitride (ZrN), hafnium nitride (HfN), chromium nitride (CrN), and molybdenum nitride (MoN), and metal coatings of copper (Cu) and gold (Au); and develop new alloyed hard coatings of titanium aluminum nitride (Ti(0.5)Al(0.5)N), titanium zirconium nitride (Ti(0.5)Zr(0.5)N), and titanium aluminum vanadium nitride.

  4. Downscaling MODIS Land Surface Temperature for Urban Public Health Applications

    NASA Astrophysics Data System (ADS)

    Al-Hamdan, M. Z.; Crosson, W. L.; Estes, M. G., Jr.; Estes, S. M.; Quattrochi, D. A.; Johnson, D.

    2013-12-01

    This study is part of a project funded by the NASA Applied Sciences Public Health Program, which focuses on Earth science applications of remote sensing data for enhancing public health decision-making. Heat related death is currently the number one weather-related killer in the United States. Mortality from these events is expected to increase as a function of climate change. This activity sought to augment current Heat Watch/Warning Systems (HWWS) with NASA remotely sensed data, and models used in conjunction with socioeconomic and heat-related mortality data. The current HWWS do not take into account intra-urban spatial variations in risk assessment. The purpose of this effort is to evaluate a potential method to improve spatial delineation of risk from extreme heat events in urban environments by integrating sociodemographic risk factors with land surface temperature (LST) estimates derived from thermal remote sensing data. In order to further improve the assessment of intra-urban variations in risk from extreme heat, we developed and evaluated a number of spatial statistical techniques for downscaling the 1-km daily MODerate-resolution Imaging Spectroradiometer (MODIS) LST data to 60 m using Landsat-derived LST data, which have finer spatial but coarser temporal resolution than MODIS. We will present these techniques, which have been demonstrated and validated for Phoenix, AZ using data from the summers of 2000-2006.

  5. Manganese perovskites for room temperature magnetic refrigeration applications

    NASA Astrophysics Data System (ADS)

    Phan, Manh-Huong; Peng, Hua-Xin; Yu, Seong-Cho; Tho, Nguyen Duc; Nhat, Hoang Nam; Chau, Nguyen

    2007-09-01

    We found the large magnetocaloric effect (MCE) in La 0.6Ca 0.3Pb 0.1MnO 3 (sample No. 1), La 0.7Ca 0.2Pb 0.1MnO 3 (sample No. 2), and La 0.7Ca 0.1Pb 0.2MnO 3 (sample No. 3) perovskites, which were prepared by a conventional ceramic method. For a magnetic field change of 13.5 kOe, the magnetic entropy change (Δ SM) reached values of 2.55, 2.53 and 3.72 J/kg K for samples Nos. 1, 2 and 3, respectively. Interestingly, the large Δ SM was found to occur around 300 K for all samples investigated, which allows magnetic refrigeration at room temperature. These perovskites have the large magnetic entropy changes induced by low magnetic field change, which is beneficial for the household application of active magnetic refrigerant (AMR) materials.

  6. Physiological responses and scope for growth upon medium-term exposure to the combined effects of ocean acidification and temperature in a subtidal scavenger Nassarius conoidalis.

    PubMed

    Zhang, Haoyu; Shin, Paul K S; Cheung, S G

    2015-05-01

    Physiological responses (ingestion rate, absorption rate and efficiency, respiration, rate, excretion rate) and scope for growth of a subtidal scavenging gastropod Nassarius conoidalis under the combined effects of ocean acidification (pCO2 levels: 380, 950, 1250 μatm) and temperature (15, 30 °C) were investigated for 31 days. There was a significant reduction in all the physiological rates and scope for growth following short-term exposure (1-3 days) to elevated pCO2 except absorption efficiency at 15 °C and 30 °C, and respiration rate and excretion rate at 15 °C. The percentage change in the physiological rates ranged from 0% to 90% at 15 °C and from 0% to 73% at 30 °C when pCO2 was increased from 380 μatm to 1250 μatm. The effect of pCO2 on the physiological rates was enhanced at high temperature for ingestion, absorption, respiration and excretion. When the exposure period was extended to 31 days, the effect of pCO2 was significant on the ingestion rate only. All the physiological rates remained unchanged when temperature increased from 24 °C to 30 °C but the rates at 15 °C were significantly lower, irrespective of the duration of exposure. Our data suggested that a medium-term exposure to ocean acidification has no effect on the energetics of N. conoidalis. Nevertheless, the situation may be complicated by a longer term of exposure and/or a reduction in salinity in a warming world. PMID:25771491

  7. X-Aerogels for Structural Components and High Temperature Applications

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Future NASA missions and space explorations rely on the use of materials that are strong ultra lightweight and able to withstand extreme temperatures. Aerogels are low density (0.01-0.5 g/cu cm) high porosity materials that contain a glass like structure formed through standard sol-gel chemistry. As a result of these structural properties, aerogels are excellent thermal insulators and are able to withstand temperatures in excess of l,000 C. The open structure of aerogels, however, renders these materials extremely fragile (fracturing at stress forces less than 0.5 N/sq cm). The goal of NASA Glenn Research Center is to increase the strength of these materials by templating polymers and metals onto the surface of an aerogel network facilitating the use of this material for practical applications such as structural components of space vehicles used in exploration. The work this past year focused on two areas; (1) the research and development of new templated aerogels materials and (2) process development for future manufacturing of structural components. Research and development occurred on the production and characterization of new templating materials onto the standard silica aerogel. Materials examined included polymers such as polyimides, fluorinated isocyanates and epoxies, and, metals such as silver, gold and platinum. The final properties indicated that the density of the material formed using an isocyanate is around 0.50 g/cc with a strength greater than that of steel and has low thermal conductivity. The process used to construct these materials is extremely time consuming and labor intensive. One aspect of the project involved investigating the feasibility of shortening the process time by preparing the aerogels in the templating solvent. Traditionally the polymerization used THF as the solvent and after several washes to remove any residual monomers and water, the solvent around the aerogels was changed to acetonitrile for the templating step. This process

  8. Development and application of high-temperature sensors and electronics for propulsion applications

    NASA Astrophysics Data System (ADS)

    Hunter, Gary W.; Wrbanek, John D.; Okojie, Robert S.; Neudeck, Philip G.; Fralick, Gustave C.; Chen, Liangyu; Xu, Jennifer; Beheim, Glenn M.

    2006-05-01

    High temperature sensors and electronics are necessary for a number of aerospace propulsion applications. The Sensors and Electronics Branch at NASA Glenn Research Center (NASA GRC) has been involved in the design, fabrication, and application of a range of sensors and electronics that have use in high temperature, harsh environment propulsion environments. The emphasis is on developing advanced capabilities for measurement and control of aeropropulsion systems as well as monitoring the safety of those systems using Micro/Nano technologies. Specific areas of work include SiC based electronic devices and sensors; thin film thermocouples, strain gauges, and heat flux gauges; chemical sensors; as well as integrated and multifunctional sensor systems. Each sensor type has its own technical challenges related to integration and reliability in a given application. These activities have a common goal of improving the awareness of the state of the propulsion system and moving towards the realization of intelligent engines. This paper will give an overview of the broad range of sensor-related development activities on-going in the NASA GRC Sensors and Electronics Branch as well as their current and potential use in propulsion systems.

  9. Li-Ion Cell Development for Low Temperature Applications

    NASA Technical Reports Server (NTRS)

    Huang, C.-K.; Sakamoto, J. S.; Surampudi, S.; Wolfenstine, J.

    2000-01-01

    JPL is involved in the development of rechargeable Li-ion cells for future Mars Exploration Missions. The specific objectives are to improve the Li-ion cell cycle life performance and rate capability at low temperature (<<-20 C) in order to enhance survivability of the Mars lander and rover batteries. Poor Li-ion rate capability at low temperature has been attributed to: (1) the electrolytes becoming viscous or freezing and/or (2) reduced electrode capacity that results from decreased Li diffusivity. Our efforts focus on increasing the rate capability at low temperature for Li-ion cells. In order to improve the rate capability we evaluated the following: (1) cathode performance at low temperatures, (2) electrode active material particle size on low temperature performance and (3) Li diffusivity at room temperature and low temperatures. In this paper, we will discuss the results of our study.

  10. High transition-temperature SQUID magnetometers and practical applications

    SciTech Connect

    Dantsker, E

    1997-05-01

    The design, fabrication and performance of SQUID magnetometers based on thin films of the high-transition temperature superconductor YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} (YBCO) are described. Essential to the achieving high magnetic field resolution at low frequencies is the elimination of 1/f flux noise due to thermally activated hopping of flux vortices between pinning sites in the superconducting films. Through improvements in processing, 1/f noise in single layer YBCO thin films and YBCO-SrTiO{sub 3}-YBCO trilayers was systematically reduced to allow fabrication of sensitive SQUID magnetometers. Both single-layer directly coupled SQUID magnetometers and multilayer magnetometers were fabricated, based on the dc SQUID with bicrystal grain boundary Josephson junctions. Multilayer magnetometers had a lower magnetic field noise for a given physical size due to greater effective sensing areas. A magnetometer consisting of a SQUID inductively coupled to the multiturn input coil of a flux transformer in a flip-chip arrangement had a field noise of 27 fT Hz{sup {minus}1/2} at 1 Hz and 8.5 fT Hz{sup {minus}1/2} at 1 kHz. A multiloop multilayer SQUID magnetometer had a field noise of 37 fT Hz{sup {minus}1/2} at 1 Hz and 18 fT Hz{sup {minus}1/2} at 1 kHz. A three-axis SQUID magnetometer for geophysical applications was constructed and operated in the field in the presence of 60 Hz and radiofrequency noise. Clinical quality magnetocardiograms were measured using multilayer SQUID magnetometers in a magnetically shielded room.

  11. Performance Characteristics of Lithium Ion Cells for Low Temperature Applications

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; Huang, C. K.; Surampudi, S.

    1998-01-01

    Several of NASA's future Planetary Exploration (specifically Mars) missions will require rechargeable batteries of high specific energy and energy density and more importantly of good low temperature performance.

  12. Application of Phosphor Thermometry to a Galvanneal Temperature Measurement System

    SciTech Connect

    Beshears, D.L.; Allison, S.W.; Andrews, W.H.; Cates, M.R.; Grann, E.B.; Manges, W.W.; McIntyre, T.J.; Scudiere, M.B.; Simpson, M.L.; Childs, R.M.; Vehec, J.; Zhang, L.

    1999-06-01

    The Galvanneal Temperature Measurement System (GTMS) was developed for the American Iron and Steel Institute by the Oak Ridge National Laboratory through a partnership with the National Steel Midwest Division in Portage, Indiana. The GTMS provides crucial on-line thermal process control information during the manufacturing of galvanneal steel. The system has been used with the induction furnaces to measure temperatures ranging from 840 to 1292 F with an accuracy of better than {+-}9 F. The GTMS provides accurate, reliable temperature information thus ensuring a high quality product, reducing waste, and saving energy. The production of uniform, high-quality galvanneal steel is only possible through strict temperature control.

  13. Electrical Devices and Circuits for Low Temperature Space Applications

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    The environmental temperature in many NASA missions, such as deep space probes and outer planetary exploration, is significantly below the range for which conventional commercial-off-the-shelf electronics is designed. Presently, spacecraft operating in the cold environment of such deep space missions carry a large number of radioisotope or other heating units in order to maintain the surrounding temperature of the on-board electronics at approximately 20 C. Electronic devices and circuits capable of operation at cryogenic temperatures will not only tolerate the harsh environment of deep space but also will reduce system size and weight by eliminating or reducing the heating units and their associate structures; thereby reducing system development cost as well as launch costs. In addition, power electronic circuits designed for operation at low temperatures are expected to result in more efficient systems than those at room temperature. This improvement results from better behavior in the electrical and thermal properties of some semiconductor and dielectric materials at low temperatures. An on-going research and development program on low temperature electronics at the NASA Glenn Research Center focuses on the development of efficient electrical systems and circuits capable of surviving and exploiting the advantages of low temperature environments. An overview of the program will be presented in this paper. A description of the low temperature test facilities along with selected data obtained from in-house component testing will also be discussed. On-going research activities that are being performed in collaboration with various organizations will also be presented.

  14. Applications of room temperature ionic liquids in interfacial polymerization

    NASA Astrophysics Data System (ADS)

    Zhu, Lining

    2006-12-01

    Room temperature ionic liquids (ILs), with their unique physical and chemical properties, have been of great interest in various areas of chemical science and engineering during the last decade. In this dissertation, polyurea and polyamide films with surface nanostructures were synthesized by interfacial polymerization (IP) with ILs without stirring. Both polymers were prepared at the interface between n-hexane and a series of 1-alkyl-3-methylimidazolium ILs. Nanoporous or nanofibrous polymer morphologies with various sizes ranging from 50 to 500 nm and geometries, depending on the ILs used, were observed by scanning electron microscopy (SEM). A correlation length of ˜20nm and a suppression of three-dimensional (3-D) crystalline structure of the polyurea were found by small angle X-ray scattering (SAXS) and X-ray diffraction (XRD), respectively. FTIR spectra showed no significant changes in the chemical composition of the polymer by the employment of ILs. The peculiar nanostructure of the polymer could be ascribed to the intermolecular interactions between the ILs and the polymer, which affected the development of the polymer morphology. The polyamides prepared with ILs showed larger intrinsic viscosities, and consequently higher molecular weights, compared to the one prepared without ILs; this could be due to the prevention of the side reaction between sebacoyl chloride and water. The enhancement of the molecular weight renders a better thermal stability to the polyamide film, as revealed by thermogravimetric analysis (TGA) which showed a higher decomposition temperature. Coating of fine particulates with polyurea by IP has been developed. With increasing stirring speed in the coating process, a decreased mean particle size and a narrower particle size distribution, as well as a lower coating weight percentage were found by particle size analysis and TGA, respectively. A Porous coating layer was formed in the IP coating in the presence of ILs. The reaction

  15. Ultrasonic level and temperature sensor for power reactor applications

    SciTech Connect

    Dress, W.B.: Miller, G.N.

    1983-01-01

    An ultrasonic waveguide employing torsional and extensional acoustic waves has been developed for use as a level and temperature sensor in pressurized and boiling water nuclear power reactors. Features of the device include continuous measurement of level, density, and temperature producing a real-time profile of these parameters along a chosen path through the reactor vessel.

  16. High Temperature Thermocouples For In-pile Applications

    SciTech Connect

    J. L. Rempe; S. C. Wilkins

    2005-10-01

    Traditional methods for measuring temperature in-pile degrade at temperatures above 1080 degrees C. Hence, a project has been initiated to explore the use of specialized thermocouples that are composed of materials that are able to withstand higher temperature, in-pile test conditions. Results from efforts to develop, fabricate and evaluate the performance of these specialized thermocouples are reported in this paper. Candidate materials were evaluated for their ability to withstand irradiation, to resit material interactions and to remain ductile at high temperatures. In addition, candidate thermocouples were evaluated based on their resolution over the temperature ranges of interest. Results from these evaluations are reported, and additional on-going development activities are summarized.

  17. Characterizations of atmospheric pressure low temperature plasma jets and their applications

    NASA Astrophysics Data System (ADS)

    Karakas, Erdinc

    2011-12-01

    Atmospheric pressure low temperature plasma jets (APLTPJs) driven by short pulses have recently received great attention because of their potential in biomedical and environmental applications. This potential is due to their user-friendly features, such as low temperature, low risk of arcing, operation at atmospheric pressure, easy handheld operation, and low concentration of ozone generation. Recent experimental observations indicate that an ionization wave exists and propagates along the plasma jet. The plasma jet created by this ionization wave is not a continuous medium but rather consists of a bullet-like-structure known as "Plasma Bullet". More interestingly, these plasma bullets actually have a donut-shaped makeup. The nature of the plasma bullet is especially interesting because it propagates in the ambient air at supersonic velocities without any externally applied electric field. In this dissertation, experimental insights are reported regarding the physical and chemical characteristics of the APLTPJs. The dynamics of the plasma bullet are investigated by means of a high-speed ICCD camera. A plasma bullet propagation model based on the streamer theory is confirmed with adequate explanations. It is also found that a secondary discharge, ignited by the charge accumulation on the dielectric electrode surfaces at the end of the applied voltage, interrupts the plasma bullet propagation due to an opposing current along the ionization channel. The reason for this interesting phenomenon is explained in detail. The plasma bullet comes to an end when the helium mole fraction along the ionization channel, or applied voltage, or both, are less than some critical values. The presence of an inert gas channel in the surrounding air, such as helium or argon, has a critical role in plasma bullet formation and propagation. For this reason, a fluid dynamics study is employed by a commercially available simulation software, COMSOL, based on finite element method. Spatio

  18. Application of low-cost algal nitrogen source feeding in fuel ethanol production using high gravity sweet potato medium.

    PubMed

    Shen, Yu; Guo, Jin-Song; Chen, You-Peng; Zhang, Hai-Dong; Zheng, Xu-Xu; Zhang, Xian-Ming; Bai, Feng-Wu

    2012-08-31

    Protein-rich bloom algae biomass was employed as nitrogen source in fuel ethanol fermentation using high gravity sweet potato medium containing 210.0 g l(-1) glucose. In batch mode, the fermentation could not accomplish even in 120 h without any feeding of nitrogen source. While, the feeding of acid-hydrolyzed bloom algae powder (AHBAP) notably promoted fermentation process but untreated bloom algae powder (UBAP) was less effective than AHBAP. The fermentation times were reduced to 96, 72, and 72 h if 5.0, 10.0, and 20.0 g l(-1) AHBAP were added into medium, respectively, and the ethanol yields and productivities increased with increasing amount of feeding AHBAP. The continuous fermentations were performed in a three-stage reactor system. Final concentrations of ethanol up to 103.2 and 104.3 g l(-1) with 4.4 and 5.3 g l(-1) residual glucose were obtained using the previously mentioned medium feeding with 20.0 and 30.0 g l(-1) AHBAP, at dilution rate of 0.02 h(-1). Notably, only 78.5 g l(-1) ethanol and 41.6 g l(-1) residual glucose were obtained in the comparative test without any nitrogen source feeding. Amino acids analysis showed that approximately 67% of the protein in the algal biomass was hydrolyzed and released into the medium, serving as the available nitrogen nutrition for yeast growth and metabolism. Both batch and continuous fermentations showed similar fermentation parameters when 20.0 and 30.0 g l(-1) AHBAP were fed, indicating that the level of available nitrogen in the medium should be limited, and an algal nitrogen source feeding amount higher than 20.0 g l(-1) did not further improve the fermentation performance. PMID:22387426

  19. Applicability and performance of an imaging plate at subzero temperatures.

    PubMed

    Sakoda, Akihiro; Ishimori, Yuu; Hanamoto, Katsumi; Kawabe, Atsushi; Kataoka, Takahiro; Nagamatsu, Tomohiro; Yamaoka, Kiyonori

    2010-10-01

    The performance of imaging plates (IPs) has not been studied at temperatures lower than 0 degrees C. In the present study, an IP was irradiated with gamma rays emitted from the mineral monazite at temperatures between -80 and 30 degrees C to determine its fundamental properties. The IP response as a function of irradiation time was found to be linear, suggesting that the IP works properly at low temperatures. Fading, an effect which should be considered at temperatures of more than 0 degrees C, was not observed at -30 and -80 degrees C. Furthermore, the fading-corrected PSL value of the IP irradiated at -80 degrees C was lower than at other temperatures (30, 5 and -30 degrees C). This can be explained by thermostimulated luminescence (TSL). Since the only intensive TSL peak in the temperature range from -80 to 30 degrees C is present at about -43 degrees C, some of the electrons trapped at F centers recombine with holes through the process of TSL before the stored radiation image is read out at room temperature. This finding suggests that the apparent sensitivity of the IP is lower at -80 degrees C although it is similar to sensitivities between -30 and 30 degrees C. This low sensitivity should be corrected to perform quantitative measurements. PMID:20385500

  20. New Optical Sensor Suite for Ultrahigh Temperature Fossil Fuel Applications

    SciTech Connect

    Russell G. May; Tony Peng; Gary Pickrell

    2005-10-31

    Development of practical, high-temperature optical claddings for improved waveguiding in sapphire fibers continued during the reporting period. A set of designed experiments using the Taguchi method was undertaken to efficiently determine the optimal set of processing variables to yield clad fibers with good optical and mechanical properties. Eighteen samples of sapphire fibers were prepared with spinel claddings, each with a unique set of variables. Statistical analyses of the results were then used to predict the set of factors that would result in a spinel cladding with the optimal geometrical, mechanical, and optical properties. To confirm the predictions of the Taguchi analysis, sapphire fibers were clad with the magnesium aluminate spinel coating using the predicted optimal set of factors. In general, the clad fibers demonstrated high quality, exceeding the best results obtained during the Phase I effort. Tests of the high-temperature stability of the clad fibers were also conducted. The results indicated that the clad fibers were stable at temperatures up to 1300 C for the duration of the three day test. At the higher temperatures, some changes in the geometry of the fibers were observed. The design, fabrication, and testing of a sapphire sensor for measurement of temperature was undertaken. The specific sensor configuration uses a polished sapphire wafer as the temperature-sensitive element. The wafer is attached to a sapphire fiber (clad or unclad), and interrogated as a Fabry-Perot sensor. Methods for assembling the sensor were investigated. A prototype sensor was fabricated and tested at room temperature and elevated temperatures. Results were difficult to interpret, due to the presence of modal noise which was found to result from the use of a spectrometer that was not designed for use with multimode fibers. A spectrometer optimized for use of multimode fiber has been obtained, and further evaluation of the sapphire temperature sensor is continuing.

  1. Mechanisms of Low-Temperature Nitridation Technology on a TaN Thin Film Resistor for Temperature Sensor Applications.

    PubMed

    Chen, Huey-Ru; Chen, Ying-Chung; Chang, Ting-Chang; Chang, Kuan-Chang; Tsai, Tsung-Ming; Chu, Tian-Jian; Shih, Chih-Cheng; Chuang, Nai-Chuan; Wang, Kao-Yuan

    2016-12-01

    In this letter, we propose a novel low-temperature nitridation technology on a tantalum nitride (TaN) thin film resistor (TFR) through supercritical carbon dioxide (SCCO2) treatment for temperature sensor applications. We also found that the sensitivity of temperature of the TaN TFR was improved about 10.2 %, which can be demonstrated from measurement of temperature coefficient of resistance (TCR). In order to understand the mechanism of SCCO2 nitridation on the TaN TFR, the carrier conduction mechanism of the device was analyzed through current fitting. The current conduction mechanism of the TaN TFR changes from hopping to a Schottky emission after the low-temperature SCCO2 nitridation treatment. A model of vacancy passivation in TaN grains with nitrogen and by SCCO2 nitridation treatment is eventually proposed to increase the isolation ability in TaN TFR, which causes the transfer of current conduction mechanisms. PMID:27251325

  2. Mechanisms of Low-Temperature Nitridation Technology on a TaN Thin Film Resistor for Temperature Sensor Applications

    NASA Astrophysics Data System (ADS)

    Chen, Huey-Ru; Chen, Ying-Chung; Chang, Ting-Chang; Chang, Kuan-Chang; Tsai, Tsung-Ming; Chu, Tian-Jian; Shih, Chih-Cheng; Chuang, Nai-Chuan; Wang, Kao-Yuan

    2016-06-01

    In this letter, we propose a novel low-temperature nitridation technology on a tantalum nitride (TaN) thin film resistor (TFR) through supercritical carbon dioxide (SCCO2) treatment for temperature sensor applications. We also found that the sensitivity of temperature of the TaN TFR was improved about 10.2 %, which can be demonstrated from measurement of temperature coefficient of resistance (TCR). In order to understand the mechanism of SCCO2 nitridation on the TaN TFR, the carrier conduction mechanism of the device was analyzed through current fitting. The current conduction mechanism of the TaN TFR changes from hopping to a Schottky emission after the low-temperature SCCO2 nitridation treatment. A model of vacancy passivation in TaN grains with nitrogen and by SCCO2 nitridation treatment is eventually proposed to increase the isolation ability in TaN TFR, which causes the transfer of current conduction mechanisms.

  3. 46 CFR 56.60-5 - Steel (High temperature applications).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ....A.) Upon prolonged exposure to temperatures above 775 °F (412 °C), the carbide phase of plain carbon... carbon-silicon steel may convert to graphite. (b) (Reproduces 124.2.B.) Upon prolonged exposure...

  4. Conductivity Analysis of Membranes for High-Temperature PEMFC Applications

    SciTech Connect

    Reed, R.; Turner, J.A.

    2005-01-01

    Low-temperature operation requirements for per-fluorinated membranes are one factor that limits the viability of current fuel cell technology for transportation and other uses. Because of this, high-temperature membrane materials are being researched. The protonic conductivity of organic/inorganic hybrid composites, Nafion® analog material, and heteropoly acid doped Nafion membranes were studied using a BekkTech® conductivity test cell as a hydrogen pump. The goal was to find a high-temperature membrane with sufficient enough conductive properties to replace the currently implemented low-temperature membranes, such as Nafion. Four-point conductivity measurements were taken using a hydrogen pump experiment. Results showed that one of the organic/inorganic membranes that we tested had similar protonic conductivity to Nafion. Nafion analog membranes were shown to have similar to slightly better conductivity than Nafion at high-temperatures. However, like Nafion, performance dropped upon dehydration of the membrane at higher temperatures. Of the heteropoly acid doped Nafion membranes studied, silicotungstic acid was found to be, overall, the most promising for use as a dopant.

  5. Ultrasonic/Sonic Drill for High Temperature Application

    NASA Technical Reports Server (NTRS)

    Bao, Xiaoqi; Bar-Cohen, Yoseph; Scott, James; Sherrit, Stewart; Widholm, Scott; Badescu, Mircea; Shrout, Tom; Jones, Beth

    2010-01-01

    Venus is one of the many significant scientific targets for NASA. New rock sampling tools with the ability to be operated at high temperatures of the order of 460 deg C are required for surface in-situ sampling/analysis missions. Piezoelectric materials such as LiNbO? crystals and Bismuth Titanate are potentially operational at the temperature range found on the surface of Venus. A study of the feasibility of producing piezoelectric drills for a temperature up to 500 deg C was conducted. The study includes investigation of the high temperature properties of piezoelectric crystals and ceramics with different formulas and doping. Several prototypes of Ultrasonic/Sonic Drill/Corers (USDC) driven by transducers using the high temperate piezoelectric ceramics and single LiNbO? crystal were fabricated. The transducers were analyzed by scanning the impedance at room temperature and 500 deg C under both low and high voltages. The drilling performances were tested at temperature up to 500 deg C. Preliminary results were previously reported [Bao et al, 2009]. In this paper, the progress is presented and the future works for performance improvements are discussed.

  6. High Temperature Metallic Seal Development For Aero Propulsion and Gas Turbine Applications

    NASA Technical Reports Server (NTRS)

    More, Greg; Datta, Amit

    2006-01-01

    A viewgraph presentation on metallic high temperature static seal development at NASA for gas turbine applications is shown. The topics include: 1) High Temperature Static Seal Development; 2) Program Review; 3) Phase IV Innovative Seal with Blade Alloy Spring; 4) Spring Design; 5) Phase IV: Innovative Seal with Blade Alloy Spring; 6) PHase IV: Testing Results; 7) Seal Seating Load; 8) Spring Seal Manufacturing; and 9) Other Applications for HIgh Temperature Spring Design

  7. Application of strong fluctuation random medium theory to scattering of electromagnetic waves from a half-space of dielectric mixture

    NASA Technical Reports Server (NTRS)

    Tsang, L.; Newton, R. W.; Kong, J. A.

    1982-01-01

    The strong fluctuation random medium theory is applied to calculate scattering from a half-space of dielectric mixture. The first and second moments of the fields are calculated, respectively, by using the bilocal and the distorted Born approximations, and the low frequency limit is taken. The singularity of the dyadic Green's function is taken into account. Expressions for the effective permittivity for the full space case are derived. It is shown that the derived result of the effect permittivity is identical to that of the Polder and van Santern mixing formula. The correlation function of the random medium is obtained by using simple physical arguments and is expressed in terms of the fractional volumes and particle sizes of the constituents of the mixture. Backscattering coefficients of a half-space dielectric mixture are also calculated. Numerical results of the effective permittivity and backscattering coefficients are illustrated using typical parameters encountered in microwave remote sensing of dry and wet snow. It is also shown that experimental data can be matched with the theory by using physical parameters of the medium as obtained from ground truth measurements.

  8. New medium for isolating propionibacteria and its application to assay of normal flora of human facial skin.

    PubMed Central

    Kishishita, M; Ushijima, T; Ozaki, Y; Ito, Y

    1980-01-01

    The conditions for isolation and cultivation of Propionibacterium acnes and related propionibacteria were studied in detail. Triton X-100 added to the diluent inhibited the growth of propionibacteria in concentrations of 0.05 to 0.1%. However, such was not the case with Tween 80; rather, growth of the bacteria was further enhanced by this agent. Consequently, Tween 80 was considered to be a suitable surfactant for addition to the diluent for isolation of propionibacteria. A new medium for isolating propionibacteria from human skin was developed. Comparative studies with colonies of P. acnes, Propionibacterium granulosum, and Staphylococcus epidermidis showed morphological differences among the colonies; thus, the medium was very useful for differentiating and identifying species of the microbes. The new medium was used for studies on the distribution of propionibacteria on the foreheads of 30 Japanese volunteers. Among 447 strains of P. acnes and 86 strains of P. granulosum isolated from the volunteers, all strains of the former were positive for indole, nitrate, milk, and gelatin hydrolysis, whereas all strains of the latter were negative for all of the tests. Images PMID:7470244

  9. Metals Technology for Aerospace Applications in 2020: Development of High Temperature Aluminum Alloys For Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Dicus, Dennis (Technical Monitor); Starke, Edgar A., Jr.

    2003-01-01

    The role of trace additions on the nucleation and stability of the primary strengthening phase, omega, is of paramount importance for the enhancement of mechanical properties for moderate temperature application of Al-Cu-Mg-(Ag) alloys. In order to better understand the competition for solute, which governs the microstructural evolution of these alloys, a series of Al-Cu-Mg-Si quaternary alloys were prepared to investigate the role of trace Si additions on the nucleation of the omega phase. Si additions were found to quell omega nucleation in conjunction with the enhanced matrix precipitation of competing phases. These initial results indicate that it is necessary to overcome a critical Mg/Si ratio for omega precipitation, rather than a particular Si content.

  10. The violent interstellar medium

    NASA Technical Reports Server (NTRS)

    Mccray, R.; Snow, T. P., Jr.

    1979-01-01

    Observational evidence for high-velocity and high-temperature interstellar gas is reviewed. The physical processes that characterize this gas are described, including the ionization and emissivity of coronal gas, the behavior and appearance of high-velocity shocks, and interfaces between coronal gas and cooler interstellar gas. Hydrodynamical models for the action of supernova explosions and stellar winds on the interstellar medium are examined, and recent attempts to synthesize all the processes considered into a global model for the interstellar medium are discussed.

  11. Hypermedia as medium

    NASA Technical Reports Server (NTRS)

    Dede, Christopher J.

    1990-01-01

    Claims and rebuttals that hypermedia (the associative, nonlinear interconnection of multimedia materials) is a fundamentally innovative means of thinking and communicating are described. This representational architecture has many advantages that make it a major advance over other media; however, it also has several intrinsic problems that severly limits its effectiveness as a medium. These advantages and limits in applications are discussed.

  12. Room-temperature magnetoelectric multiferroic thin films and applications thereof

    SciTech Connect

    Katiyar, Ram S; Kuman, Ashok; Scott, James F.

    2014-08-12

    The invention provides a novel class of room-temperature, single-phase, magnetoelectric multiferroic (PbFe.sub.0.67W.sub.0.33O.sub.3).sub.x (PbZr.sub.0.53Ti.sub.0.47O.sub.3).sub.1-x (0.2.ltoreq.x.ltoreq.0.8) (PFW.sub.x-PZT.sub.1-x) thin films that exhibit high dielectric constants, high polarization, weak saturation magnetization, broad dielectric temperature peak, high-frequency dispersion, low dielectric loss and low leakage current. These properties render them to be suitable candidates for room-temperature multiferroic devices. Methods of preparation are also provided.

  13. Electrolytes for Li-Ion Cells in Low Temperature Applications

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; Surampudi, S.

    2000-01-01

    Prototype AA-size lithium-ion cells have been demonstrated to operate effectively at temperatures as low as -30 to -40 C. These improvements in low temperature cell performance have been realized by the incorporation of ethylene carbonate-based electrolytes which possess low melting, low viscosity cosolvents, such as methyl acetate, ethyl acetate, gamma-butyrolactone, and ethyl methyl carbonate. The cells containing a 0.75M LiPF6 EC+DEC+DMC+EMC (1:1:1:1) electrolyte displayed the best performance at -30 C (> 90% of the room temperature capacity at approximately C/15 rate), whereas, at -40 C the cells with the 0.75M LiPF6 EC+DEC+DMC+MA (1:1:1:1) and 0.75M LiPF6 EC+DEC+DMC+EA (1:1:1:1) electrolytes showed superior performance.

  14. Self-lubricating coatings for high-temperature applications

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.

    1990-01-01

    Solid lubricants with maximum temperature capabilities of about 1100 C are known. Unfortunately, none of the solid lubricants with the highest temperature capabilities are effective below 400 C. However, research at NASA's Lewis Research Center shows that silver and stable fluorides such as calcium and barium fluorides act synergistically to provide lubrication from below room temperature to about 900 C. This paper describes plasma-sprayed composite coatings that contain these solid lubricants in combination with a metal-bonded chromium carbide. The lubricants control friction, and the carbide matrix provides wear resistance. Successful tests of these coatings as backup lubricants for compliant gas bearings in turbomachinery and as self-lubricating liners in a four-cylinder Stirling engine are discussed.

  15. Structural application of high strength, high temperature ceramics

    NASA Technical Reports Server (NTRS)

    Hall, W. B.

    1982-01-01

    The operation of rocket engine turbine pumps is limited by the temperature restrictions of metallic components used in the systems. Mechanical strength and stability of these metallic components decrease drastically at elevated temperatures. Ceramic materials that retain high strength at high temperatures appear to be a feasible alternate material for use in the hot end of the turbopumps. This project identified and defined the processing parameters that affected the properties of Si3N4, one of candidate ceramic materials. Apparatus was assembled and put into operation to hot press Si3N4 powders into bulk material for in house evaluation. A work statement was completed to seek outside contract services to design, manufacture, and evaluate Si3N4 components in the service environments that exists in SSME turbopumps.

  16. 9 Cr-- 1 Mo steel material for high temperature application

    DOEpatents

    Jablonski, Paul D; Alman, David; Dogan, Omer; Holcomb, Gordon; Cowen, Christopher

    2012-11-27

    One or more embodiments relates to a high-temperature, titanium alloyed, 9 Cr-1 Mo steel exhibiting improved creep strength and oxidation resistance at service temperatures up to 650.degree. C. The 9 Cr-1 Mo steel has a tempered martensite microstructure and is comprised of both large (0.5-3 .mu.m) primary titanium carbides and small (5-50 nm) secondary titanium carbides in a ratio of. from about 1:1.5 to about 1.5:1. The 9 Cr-1 Mo steel may be fabricated using exemplary austenizing, rapid cooling, and tempering steps without subsequent hot working requirements. The 9 Cr-1 Mo steel exhibits improvements in total mass gain, yield strength, and time-to-rupture over ASTM P91 and ASTM P92 at the temperature and time conditions examined.

  17. 1-3 piezoelectric composites for high temperature transducer applications

    PubMed Central

    Li, Lili; Zhang, Shujun; Xu, Zhuo; Wen, Fei; Geng, Xuecang; Lee, Hyeong Jae; Shrout, Thomas R.

    2013-01-01

    High temperature Pb(Zr,Ti)O3 /epoxy 1-3 composites were fabricated using the dice and fill method. The epoxy filler was modified with glass spheres in order to improve the thermal reliability of the composites at elevated temperatures. Temperature dependent dielectric and electromechanical properties of the composites were measured after aging at 250°C with different dwelling times. Obvious cracks were observed and the electrodes were damaged in the composite with unmodified epoxy after 200 hours, leading to the failure of the composite. In contrast, composites with >12 vol% glass sphere loaded epoxies were found to exhibit minimal electrical property variation after aging for 500 hours, with dielectric permittivity, piezoelectric coefficient and electromechanical coupling being on the order of 940, 310pC/N and 57%, respectively. This is due to the improved thermal expansion behavior of the modified filler. PMID:23729863

  18. A polytetrafluorethylene insulated cable for high temperature oxygen aerospace applications

    NASA Technical Reports Server (NTRS)

    Sheppard, A. T.; Webber, R. G.

    1983-01-01

    For electrical cables to function and survive in the severe high temperature oxygen environment that will be experienced in the external tanks of the space shuttle, extreme cleanliness and material purity is required. A flexible light weight cable has been developed for use in pure oxygen at worst case temperatures of -190 to +260 degrees Centigrade and pressures as high as 44 pounds per square inch absolute. A comprehensive series of tests were performed on cables manufactured to the best commercial practices in order to establish the basic guidelines for control of build configuration as well as each material used in construction of the cable.

  19. Stability of Materials in High Temperature Water Vapor: SOFC Applications

    NASA Technical Reports Server (NTRS)

    Opila, E. J.; Jacobson, N. S.

    2010-01-01

    Solid oxide fuel cell material systems require long term stability in environments containing high-temperature water vapor. Many materials in fuel cell systems react with high-temperature water vapor to form volatile hydroxides which can degrade cell performance. In this paper, experimental methods to characterize these volatility reactions including the transpiration technique, thermogravimetric analysis, and high pressure mass spectrometry are reviewed. Experimentally determined data for chromia, silica, and alumina volatility are presented. In addition, data from the literature for the stability of other materials important in fuel cell systems are reviewed. Finally, methods for predicting material recession due to volatilization reactions are described.

  20. High temperature strain gage technology for hypersonic aircraft development applications

    NASA Technical Reports Server (NTRS)

    Anderson, W. L.; Grant, H. P.

    1992-01-01

    An experimental evaluation of Pd 13 percent Cr and of BCL-3 alloy wire strain gages was conducted on IN100 and Cu 0.15 percent Zr alloy substrates. Testing included apparent strain, drift, gage factor, and creep. Maximum test temperature was 1144 K (1600 F). The PdCr gages incorporated Pt temperature compensation elements. The PdCr gages were found to have good resistance stability below 866 K (1100 F). The BCL 3 gages were found to have good resistance stability above 800 K (981 F), but high drift around 700 K (800 F).

  1. Optical fibers with dual coatings for high-temperature applications

    NASA Astrophysics Data System (ADS)

    Stolov, Andrei A.; Simoff, Debra A.; Lindholm, Eric A.; Ciardiello, Catherine R.

    2010-10-01

    We describe a new optical fiber coating, comprising layers of UV-curable silicone and high-temperature acrylate, with and without hermetic carbon. Optical and mechanical properties of graded index 50/125 μm multimode fibers drawn with the new coating are examined. The new coatings display superior thermal stability in comparison with conventional dual acrylate coatings.

  2. Kamacite blocking temperatures and applications to lunar magnetism

    NASA Astrophysics Data System (ADS)

    Garrick-Bethell, Ian; Weiss, Benjamin P.

    2010-05-01

    The long-term stability of remanent magnetization is a requirement for paleomagnetic studies. Here we present calculations that predict the magnetic relaxation times of single domain crystals of the iron-nickel mineral kamacite as a function of their time-temperature history. Kamacite is one of the most abundant ferromagnetic minerals in the solar system and is the dominant remanence carrier on the Moon. We perform these calculations for a variety of grain sizes, times, and temperatures to derive a broad view of the remanence stability of kamacite over geologic timescales. Previously, such blocking temperature calculations were only available for the common Earth minerals magnetite, hematite, and pyrrhotite. Our results show that remanence in kamacite-bearing lunar samples is stable against typical thermal perturbations during the last several billion years of lunar history and residence on Earth. Our findings indicate that lunar paleomagnetism cannot be entirely an artifact due to sample storage in the Earth's magnetic field. Future paleomagnetic studies of iron-bearing samples can use our blocking temperature diagram to determine the effects of geologic heating events on magnetic remanence.

  3. Applications of Land Surface Temperature from Microwave Observations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Land surface temperature (LST) is a key input for physically-based retrieval algorithms of hydrological states and fluxes. Yet, it remains a poorly constrained parameter for global scale studies. The main two observational methods to remotely measure T are based on thermal infrared (TIR) observation...

  4. A Silicon Carbide Wireless Temperature Sensing System for High Temperature Applications

    PubMed Central

    Yang, Jie

    2013-01-01

    In this article, an extreme environment-capable temperature sensing system based on state-of-art silicon carbide (SiC) wireless electronics is presented. In conjunction with a Pt-Pb thermocouple, the SiC wireless sensor suite is operable at 450 °C while under centrifugal load greater than 1,000 g. This SiC wireless temperature sensing system is designed to be non-intrusively embedded inside the gas turbine generators, acquiring the temperature information of critical components such as turbine blades, and wirelessly transmitting the information to the receiver located outside the turbine engine. A prototype system was developed and verified up to 450 °C through high temperature lab testing. The combination of the extreme temperature SiC wireless telemetry technology and integrated harsh environment sensors will allow for condition-based in-situ maintenance of power generators and aircraft turbines in field operation, and can be applied in many other industries requiring extreme environment monitoring and maintenance. PMID:23377189

  5. A silicon carbide wireless temperature sensing system for high temperature applications.

    PubMed

    Yang, Jie

    2013-01-01

    In this article, an extreme environment-capable temperature sensing system based on state-of-art silicon carbide (SiC) wireless electronics is presented. In conjunction with a Pt-Pb thermocouple, the SiC wireless sensor suite is operable at 450 °C while under centrifugal load greater than 1,000 g. This SiC wireless temperature sensing system is designed to be non-intrusively embedded inside the gas turbine generators, acquiring the temperature information of critical components such as turbine blades, and wirelessly transmitting the information to the receiver located outside the turbine engine. A prototype system was developed and verified up to 450 °C through high temperature lab testing. The combination of the extreme temperature SiC wireless telemetry technology and integrated harsh environment sensors will allow for condition-based in-situ maintenance of power generators and aircraft turbines in field operation, and can be applied in many other industries requiring extreme environment monitoring and maintenance. PMID:23377189

  6. Advances in processing of NiAl intermetallic alloys and composites for high temperature aerospace applications

    NASA Astrophysics Data System (ADS)

    Bochenek, Kamil; Basista, Michal

    2015-11-01

    Over the last few decades intermetallic compounds such as NiAl have been considered as potential high temperature structural materials for aerospace industry. A large number of investigations have been reported describing complex fabrication routes, introducing various reinforcing/alloying elements along with theoretical analyses. These research works were mainly focused on the overcoming of main disadvantage of nickel aluminides that still restricts their application range, i.e. brittleness at room temperature. In this paper we present an overview of research on NiAl processing and indicate methods that are promising in solving the low fracture toughness issue at room temperature. Other material properties relevant for high temperature applications are also addressed. The analysis is primarily done from the perspective of NiAl application in aero engines in temperature regimes from room up to the operating temperature (over 1150 °C) of turbine blades.

  7. Accelerator measurement of NaI response to medium energy neutrons and application to a satellite-borne spectrometer

    NASA Technical Reports Server (NTRS)

    Dunphy, P. P.; Chupp, E. L.; Popecki, M.; Forrest, D. J.; Lopiano, D.; Shima, T.; Spinka, H.; Glass, G.; Burleson, G.; Beddo, M.

    1992-01-01

    We report on the response of a prototype detector to medium energy neutrons. The neutrons were produced by n-p scattering of a neutron beam on a hydrogen target. The measurements provide unique data on the efficiency and response of large NaI scintillators to neutrons in the energy range 36-709 MeV. We apply the results to the high-energy mode of the Gamma-Ray Spectrometer (GRS) on the Solar Maximum Mission satellite by estimating its efficiency for neutron detection. This estimate is compared to earlier Monte Carlo calculations of the GRS efficiency.

  8. Application of the Monte Carlo method for modeling passage of ultrashort laser pulses through an inhomogeneous medium with moving scatterers

    NASA Astrophysics Data System (ADS)

    Starukhin, P. Yu.; Klinaev, Yu. V.

    2011-05-01

    We present the results of numerical modeling of passage of ultrashort laser pulses through an inhomogeneous layered medium with moving scatterers, based on solution of the nonsteady-state radiation transport equation by the Monte Carlo method. We consider the effects of Doppler broadening of the backscattered radiation spectrum in biological tissues. We have analyzed the dynamics of propagation of a short laser pulse within a multilayer model of human skin. We have studied the possibilities for tomography of different layers of biological tissue based on analysis of the spectrum of the scattered radiation pulse.

  9. Temperature accelerated dynamics : introduction and application to crystal growth.

    SciTech Connect

    Montalenti, F.

    2002-01-01

    Temperature accelerated dynamics (TAD) simulations allow one to reach long time scales without needing any a priori information on the system dynamics. As a consequence, TAD is a powerful method for simulating complex phenomena where the dynamics is highly unpredictable and the time scale is longer than the one reachable by standard molecular dynamics (ns-ps) . In this paper, we shall focus our attention on crystal growth. We give an overview of the TAD method, and we demonstrate that at low temperatures a TAD simulation can be faster than a standard molecular dynamics simulation by several orders of magnitude, allowing one to match typical experimental time scales of seconds or longer. Moreover, we explicitely show how critical it is to match the experimental time scale, in order to predict the correct geometry of the growing surface.

  10. Metal-metal laminar composites for high-temperature applications.

    NASA Technical Reports Server (NTRS)

    Hoffman, C. A.; Weeton, J. W.

    1973-01-01

    A study was conducted to obtain indications of the potentialities of laminar metal-metal composites for elevated-temperature use. Most of the composites consisted of multiple layers or laminae of tungsten alternated with laminae of Nichrome V, a ductile, weaker, but oxidation-resistant alloy. Composites with 50 vol % of each phase made from 0.0025 cm, 0.0125 cm, or 0.050 cm laminae, were tested in tension and stress rupture at temperatures of 871 and 1093 C and in impact at 23 and 524 C. A tension and a short-time stress-rupture test was conducted on specimens of 77 vol % W-Re-Hf-C/23 vol % Inconel Alloy 600 at 1093 C.

  11. Metal-metal laminar composites for high temperature applications

    NASA Technical Reports Server (NTRS)

    Hoffman, C. A.; Weeton, J. W.

    1972-01-01

    A study was conducted to obtain indications of the potentialities of laminar metal-metal composites for elevated temperature use. Most of the composites consisted of multiple layers or laminae of tungsten alternated with laminae of Nichrome V, a ductile, weaker but oxidation-resistant alloy. Composites with 50 volume percent of each phase were tested in tension and stress rupture at temperatures of 871 and 1093 C (1600 and 2000 F) and in impact at 23 and 524 C (73 and 975 F). A tension and a short time stress-rupture test was conducted on specimens of 77 v/o W-Re-Hf-C/23 v/o Inconel alloy 600 at 1093 C (2000 F).

  12. Iron aluminide alloys with improved properties for high temperature applications

    DOEpatents

    McKamey, C.G.; Liu, C.T.

    1990-10-09

    An improved iron aluminide alloy of the DO[sub 3] type is described that has increased room temperature ductility and improved high elevated temperature strength. The alloy system further is resistant to corrosive attack in the environments of advanced energy conversion systems such as those using fossil fuels. The resultant alloy is relatively inexpensive as contrasted to nickel based and high nickel steels currently utilized for structural components. The alloy system consists essentially of 26--30 at. % aluminum, 0.5--10 at. % chromium, 0.02--0.3 at. % boron plus carbon, up to 2 at. % molybdenum, up to 1 at. % niobium, up to 0.5 at. % zirconium, up to 0.1 at. % yttrium, up to 0.5 at. % vanadium and the balance iron. 3 figs.

  13. Iron aluminide alloys with improved properties for high temperature applications

    DOEpatents

    McKamey, Claudette G.; Liu, Chain T.

    1990-01-01

    An improved iron aluminide alloy of the DO.sub.3 type that has increased room temperature ductility and improved high elevated temperature strength. The alloy system further is resistant to corrosive attack in the environments of advanced energy corrosion systems such as those using fossil fuels. The resultant alloy is relatively inexpensive as contrasted to nickel based and high nickel steels currently utilized for structural components. The alloy system consists essentially of 26-30 at. % aluminum, 0.5-10 at. % chromium, 0.02-0.3 at. % boron plus carbon, up to 2 at. % molybdenum, up to 1 at. % niobium, up to 0.5 at. % zirconium, up to 0.1 at. % yttrium, up to 0.5 at. % vanadium and the balance iron.

  14. Development of integrated thermionic circuits for high-temperature applications

    SciTech Connect

    McCormick, J.B.; Wilde, D.; Depp, S.; Hamilton, D.J.; Kerwin, W.

    1981-01-01

    This report describes a class of microminiature, thin film devices known as integrated thermionic circuits (ITC) capable of extended operation in ambient temperatures up to 500/sup 0/C. The evolution of the ITC concept is discussed. A set of practical design and performance equations is demonstrated. Recent experimental results are discussed in which both devices and simple circuits have successfully operated in 500/sup 0/C environments for extended periods of time (greater than 11,000 hours).

  15. Thermal Barrier/Seal for Extreme Temperature Applications

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M.; Dunlap, Patrick H., Jr.; Phelps, Jack; Bauer, Paul; Bond, Bruce; McCool, Alex (Technical Monitor)

    2002-01-01

    Large solid rocket motors, as found on the Space Shuttle, are fabricated in segments for manufacturing considerations, bolted together, and sealed using conventional Viton O-ring seals. Similarly the nine large solid rocket motor nozzles are assembled from several different segments, bolted together, and sealed at six joint locations using conventional O-ring seals. The 5500 F combustion gases are generally kept a safe distance away from the seals by thick layers of phenolic or rubber insulation. Joint-fill compounds, including RTV (room temperature vulcanized compound) and polysulfide filler, are used to fill the joints in the insulation to prevent a direct flow-path to the O-rings. Normally these two stages of protection are enough to prevent a direct flow-path of the 900-psi hot gases from reaching the temperature-sensitive O-ring seals. However, in the current design 1 out of 15 Space Shuttle solid rocket motors experience hot gas effects on the Joint 6 wiper (sacrificial) O-rings. Also worrisome is the fact that joints have experienced heat effects on materials between the RTV and the O-rings, and in two cases O-rings have experienced heat effects. These conditions lead to extensive reviews of the post-flight conditions as part of the effort to monitor flight safety. We have developed a braided carbon fiber thermal barrier to replace the joint fill compounds in the Space Shuttle solid rocket motor nozzles to reduce the incoming 5500 F combustion gas temperature and permit only cool (approximately 100 F) gas to reach the temperature-sensitive O-ring seals. Implementation of this thermal barrier provides more robust, consistent operation with shorter turn around times between Shuttle launches.

  16. Low temperature high frequency coaxial pulse tube for space application

    SciTech Connect

    Charrier, Aurelia; Charles, Ivan; Rousset, Bernard; Duval, Jean-Marc

    2014-01-29

    The 4K stage is a critical step for space missions. The Hershel mission is using a helium bath, which is consumed day by day (after depletion, the space mission is over) while the Plank mission is equipped with one He4 Joule-Thomson cooler. Cryogenic chain without helium bath is a challenge for space missions and 4.2K Pulse-Tube working at high frequency (around 30Hz) is one option to take it up. A low temperature Pulse-Tube would be suitable for the ESA space mission EChO (Exoplanet Characterisation Observatory, expected launch in 2022), which requires around 30mW cooling power at 6K; and for the ESA space mission ATHENA (Advanced Telescope for High ENergy Astrophysics), to pre-cool the sub-kelvin cooler (few hundreds of mW at 15K). The test bench described in this paper combines a Gifford-McMahon with a coaxial Pulse-Tube. A thermal link is joining the intercept of the Pulse-Tube and the second stage of the Gifford-McMahon. This intercept is a separator between the hot and the cold regenerators of the Pulse-Tube. The work has been focused on the cold part of this cold finger. Coupled with an active phase shifter, this Pulse-Tube has been tested and optimized and temperatures as low as 6K have been obtained at 30Hz with an intercept temperature at 20K.

  17. Low Temperature Atmospheric Argon Plasma: Diagnostics and Medical Applications

    NASA Astrophysics Data System (ADS)

    Ermolaeva, Svetlana; Petrov, Oleg; Zigangirova, Nailya; Vasiliev, Mikhail; Sysolyatina, Elena; Antipov, Sergei; Alyapyshev, Maxim; Kolkova, Natalia; Mukhachev, Andrei; Naroditsky, Boris; Shimizu, Tetsuji; Grigoriev, Anatoly; Morfill, Gregor; Fortov, Vladimir; Gintsburg, Alexander

    This study was devoted to diagnostic of low temperature plasma produced by microwave generator and investigation of its bactericidal effect against bacteria in biofilms and within eukaryotic cells. The profile of gas temperature near the torch outlet was measured. The spectrum in a wide range of wavelengths was derived by the method of optical emission spec-troscopy. Probe measurements of the floating potential of plasma were car-ried out. The estimation and adaptation of parameters of plasma flow (tem-perature, velocity, ion number density) according to medico-technical requirements were produced. The model of immersed surface-associated biofilms formed by Gram-negative bacteria, Pseudomonas aeruginosa and Burkholderia cenocepacia, and Gram-positive bacteria, Staphylococcus aureus, was used to assess bactericidal effects of plasma treatment. Reduction in the concentration of live bacteria in biofilms treated with plasma for 5 min was demonstrated by measuring Live/Dead fluorescent labeling and using direct plating. The intracellular infection model with the pathogenic bacterium, Chlamydia trachomatis, was used to study the efficacy of microwave argon plasma against intracellular parasites. A 2 min plasma treatment of mouse cells infected with C. trachomatis reduced infectious bacteria by a factor of 2×106. Plasma treatment diminished the number of viable host cells by about 20%. When the samples were covered with MgF2 glass to obstruct active particles and UV alone was applied, the bactericidal effect was re-duced by 5×104 fold compared to the whole plasma.

  18. Potential power sources for high-temperature geothermal applications

    SciTech Connect

    Guidotti, R.A.; Dobranich, D

    1996-05-01

    The thermal response under geothermal-borehole conditions of a conventional thermal battery was evaluated for various designs by numerical simulations using a finite-element thermal model. This technology, which is based on molten salts, may be suitable as a power source for geothermal borehole applications for data logging. Several promising candidate electrolytes were identified for further study.

  19. Applications of American design codes for elevated temperature environment. [LMFBR

    SciTech Connect

    Severud, L.K.

    1980-03-01

    A brief summary of the ASME Code rules of Case N-47 is presented. An overview of the typical procedure used to demonstrate Code compliance is provided. Application experience and some examples of detailed inelastic analysis and simplified-approximate methods are given. Recent developments and future trends in design criteria and ASME Code rules are also presented.

  20. Advanced Ceramic Matrix Composites (CMCs) for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Singh, M.

    2005-01-01

    Advanced ceramic matrix composites (CMCs) are enabling materials for a number of demanding applications in aerospace, energy, and nuclear industries. In the aerospace systems, these materials are being considered for applications in hot sections of jet engines such as the combustor liner, vanes, nozzle components, nose cones, leading edges of reentry vehicles, and space propulsion components. Applications in the energy and environmental industries include radiant heater tubes, heat exchangers, heat recuperators, gas and diesel particulate filters, and components for land based turbines for power generation. These materials are also being considered for use in the first wall and blanket components of fusion reactors. In the last few years, a number of CMC components have been developed and successfully tested for various aerospace and ground based applications. However, a number of challenges still remain slowing the wide scale implementation of these materials. They include robust fabrication and manufacturing, assembly and integration, coatings, property modeling and life prediction, design codes and databases, repair and refurbishment, and cost. Fabrication of net and complex shape components with high density and tailorable matrix properties is quite expensive, and even then various desirable properties are not achievable. In this presentation, a number of examples of successful CMC component development and testing will be provided. In addition, critical need for robust manufacturing, joining and assembly technologies in successful implementation of these systems will be discussed.

  1. High temperature superconductive microwave technology for space applications

    NASA Technical Reports Server (NTRS)

    Leonard, R. F.; Connolly, D. J.; Bhasin, K. B.; Warner, J. D.; Alterovitz, S. A.

    1991-01-01

    Progress being made on space application technology research on film fabrication, passive microwave circuits, and semiconductor devices for cryogenic circuits is reviewed. Achievements in YBCO and TCBCO films are addressed along with circuit evaluations of microstrip resonators, phase shifters, microstrip filters, dielectric resonator filters, and superconducting antennas.

  2. Application of Principal Component Analysis to Large-Scale Spectral Line Imaging Studies of the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Heyer, Mark H.; Peter Schloerb, F.

    1997-01-01

    The multivariate statistical technique of principal component analysis (PCA) is described and demonstrated to be a valuable tool to consolidate the large amount of information obtained with spectroscopic imaging observations of the interstellar medium. Simple interstellar cloud models with varying degrees of complexity and Gaussian noise are constructed and analyzed to demonstrate the ability of PCA to statistically extract physical features and phenomena from the data and to gauge the effects of random noise upon the analysis. Principal components are calculated for high spatial dynamic range 12CO and 13CO data cubes of the Sh 155 (Cep OB3) cloud complex. These identify the three major emission components within the cloud and the spatial differences between 12CO and 13CO emissions. Higher order eigenimages identify small velocity fluctuations and therefore provide spatial information to the turbulent velocity field within the cloud. A size line width relationship δv ~ Rα is derived from spatial and kinematic characterizations of the principal components of 12CO emission from the Sh 155, Sh 235, Sh 140, and Gem OB1 cloud complexes. The power-law indices for these clouds range from 0.42 to 0.55 and are similar to those derived from an ensemble of clouds within the Galaxy found by Larson (1981) and Solomon et al. (1987). The size-line width relationship within a given cloud provides an important diagnostic to the variation of kinetic energy with size scale within turbulent flows of the interstellar medium.

  3. New Optical Sensor Suite for Ultrahigh Temperature Fossil Fuel Application

    SciTech Connect

    John Coggin; Tom Flynn; Jonas Ivasauskas; Daniel Kominsky; Carrie Kozikowski; Russell May; Michael Miller; Tony Peng; Gary Pickrell; Raymond Rumpf; Kelly Stinson-Bagby; Dan Thorsen; Rena Wilson

    2007-12-31

    Accomplishments of a program to develop and demonstrate photonic sensor technology for the instrumentation of advanced powerplants and solid oxide fuel cells are described. The goal of this project is the research and development of advanced, robust photonic sensors based on improved sapphire optical waveguides, and the identification and demonstration of applications of the new sensors in advanced fossil fuel power plants, where the new technology will contribute to improvements in process control and monitoring.

  4. Transparent electrically conducting thin films for spacecraft temperature control applications

    NASA Technical Reports Server (NTRS)

    Hass, G.; Heaney, J. B.; Toft, A. R.

    1979-01-01

    Thin transparent films of In2O3 or In2O3 + SnO2 prepared by evaporation or sputtering have been tested for use as surface layers for spacecraft temperature control coatings. The films are intended to prevent nonuniform electric charge buildup on the spacecraft exterior. Film thicknesses of 300 to 500 A were found to be optimal in terms of durability and minimum impact on the solar absorptance and the thermal emissivity of the underlayers. As a verification of their suitability for long-duration space missions, the films were subjected to simulated solar UV plus proton irradiation in a vacuum.

  5. Low temperature nanocrystalline zinc oxide for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Greulich-Weber, S.; Arceiz Casas, S.; Weber, N.

    2015-04-01

    Nanocrystalline ZnO was synthesized by a low temperature sol-gel route. The ZnOnanocrystals were investigated by X-ray diffraction (XRD), electron paramagnetic resonance (EPR), photoluminescence (PL), and conductivity measurements. The goal was the development of nanocrystalline ZnO as a transparent conductive oxide blocking ultraviolet (uv) light and using a defect photoluminescence band for down-shifting uvlight into the visible range, where organic photoactive polymers have their absorption maximum. The resulting defects and physical properties are discussed with respect to the conductivity of ZnO nanocrystals.

  6. Miniature high-resolution thermometer for low-temperature applications

    NASA Astrophysics Data System (ADS)

    Welander, Paul B.; Hahn, Inseob

    2001-09-01

    We report on a new miniature, high-resolution, susceptibility thermometer that employs LaxGd1-xCl3 as the paramagnetic material for temperature measurement below 4 K. The thermometer utilizes small permanent disk magnets to provide the required magnetic field, and has a total mass of only 2 g. The thermometer shows a resolution of 0.2 nK in a 1 Hz bandwidth and an absolute drift rate less than 50 fK/s at 2.2 K. In this article, we describe the thermometer design, assembly procedure, and experimental test results, including its thermal time constant and susceptibility to external magnetic fields.

  7. Electrical properties of materials for high temperature strain gage applications

    NASA Technical Reports Server (NTRS)

    Brittain, John O.

    1989-01-01

    A study was done on the electrical resistance of materials that are potentially useful as resistance strain gages at high temperatures under static strain conditions. Initially a number of binary alloys were investigated. Later, third elements were added to these alloys, all of which were prepared by arc melting. Several transition metals were selected for experimentation, most prepared as thin films. Difficulties with electrical contacts thwarted efforts to extend measurements to the targeted 1000 C, but results obtained did suggest ways of improving the electrical resistance characteristics of certain materials.

  8. Superalloy for high-temperature hydrogen environmental applications

    NASA Technical Reports Server (NTRS)

    McKannan, Eugene C. (Inventor); McPherson, William B. (Inventor); Ahmed, Shaffiq (Inventor); Chandler, Shirley S. (Inventor)

    1991-01-01

    A nickel-based superalloy is provided which is resistant to deterioration in hydrogen at high operating temperatures and pressures, and which thus can be used in hydrogen-fueled spacecraft such as the Space Shuttle. The superalloy is characterized by a two-phase microstructure and consists of a gamma-prime precipitated phase in a gamma matrix. The gamma matrix phase is a primary solid solution and the gamma precipitated phase will be an intermetallic compound of the type A.sub.3 B, such as nickel aluminide or titanide. Both phases are coherent, ordered, and compatible, and thus will retain most of their strength at elevated temperatures. The alloy consists essentially of (by weight): Ni 50-60%, Cr 10-20%, Al 2-6%, Co 2-5%, Ti 3-8%, W 5-12%, Mo 5-10%, Nb 1-3%, wherein the ratio W/MO is approximately equal to 1, and Ti/Al ranges from about 1 to about 2.

  9. High temperature solder alloys for underhood applications: Final report

    SciTech Connect

    Kern, J.A.; Drewien, C.A.; Yost, F.G.; Sackinger, S.; Weiser, M.W.

    1996-06-01

    In this continued study, the microstructural evolution and peel strength as a function of thermal aging were evaluated for four Sn-Ag solders deposited on double layered Ag-Pt metallization. Additionally, activation energies for intermetallic growth over the temperature range of 134 to 190{degrees}C were obtained through thickness measurements of the Ag-Sn intermetallic that formed at the solder-metallization interface. It was found that Bi-containing solders yielded higher activation energies for the intermetallic growth, leading to thicker intermetallic layers at 175 and 190{degrees}C for times of 542 and 20.5 hrs, respectively, than the solders free of Bi. Complete reaction of the solder with the metallization occurred and lower peel strengths were measured on the Bi-containing solders. In all solder systems, a Ag-Sn intermetallic thickness of greater than {approximately}7 {mu}m contributed to lower peel strength values. The Ag-Sn binary eutectic composition and the Ag-Sn-Cu ternary eutectic composition solders yielded lower activation energies for intermetallic formation, less microstructural change with time, and higher peel strengths; these solder systems were resilient to the effects of temperatures up to 175{degrees}C. Accelerated isothermal aging studies provide useful criteria for recommendation of materials systems. The Sn-Ag and Sn-Ag-Cu eutectic compositions should be considered for future service life and reliability studies based upon their performance in this study.

  10. Nonparametric Spatial Models for Extremes: Application to Extreme Temperature Data.

    PubMed

    Fuentes, Montserrat; Henry, John; Reich, Brian

    2013-03-01

    Estimating the probability of extreme temperature events is difficult because of limited records across time and the need to extrapolate the distributions of these events, as opposed to just the mean, to locations where observations are not available. Another related issue is the need to characterize the uncertainty in the estimated probability of extreme events at different locations. Although the tools for statistical modeling of univariate extremes are well-developed, extending these tools to model spatial extreme data is an active area of research. In this paper, in order to make inference about spatial extreme events, we introduce a new nonparametric model for extremes. We present a Dirichlet-based copula model that is a flexible alternative to parametric copula models such as the normal and t-copula. The proposed modelling approach is fitted using a Bayesian framework that allow us to take into account different sources of uncertainty in the data and models. We apply our methods to annual maximum temperature values in the east-south-central United States. PMID:24058280

  11. Combined conjugated heat transfer from a scattering medium

    NASA Technical Reports Server (NTRS)

    Kassemi, M.; Chung, B. T. F.

    1992-01-01

    Combined heat transfer from a radiating and convecting flow of an absorbing, emitting, and scattering medium in a reflecting channel with conducting wall was numerically investigated. The results clearly indicate that in any high-temperature applications, if the effects of scattering and wall reflection are ignored, the position and magnitude of the maximum wall temperature and the behavior of the convective Nusselt number can be grossly misrepresented.

  12. Comparison of DD, DT and Cf-252 neutron excitation of light and medium mass nuclei for field PGNAA applications

    NASA Astrophysics Data System (ADS)

    Seabury, E. H.; Blackburn, B. W.; Chichester, D. L.; Wharton, C. J.; Caffrey, A. J.

    2007-08-01

    Prompt Gamma Ray Neutron activation analysis can offer significant cost and safety advantages in the identification of explosives and toxic chemicals. As an example, the US military examined over a thousand suspect chemical munitions with Idaho National Laboratory's PINS Chemical Assay System last year. PGNAA requires, of course, a neutron source to excite the atomic nuclei of the item under test via neutron capture and inelastic neutron scattering reactions and the choice of neutron source can drastically affect PGNAA system performance. We have carried out Monte Carlo and laboratory experiments comparing DD, DT and Cf-252 neutrons incident on light and medium mass chemical elements, toward optimizing the design of future neutron-generator-based PGNAA systems for field use. We report the excitation of (n, γ) and (n, n‧) gamma rays from these elements by each type of neutron source.

  13. Application of Low Frequency and Medium Frequency Currents in the Management of Acute and Chronic Pain-A Narrative Review

    PubMed Central

    Samuel, Stephen Rajan; Maiya, G Arun

    2015-01-01

    Trancutaneous electrical nerve stimulation (TENS) and interferential therapy (IFT) have been a regular line of treatment for various types of acute and chronic pain. This review aims to compile the latest literature in pain management using these modalities which use low-frequency and medium-frequency currents. The Cochrane Library, Scopus, PubMed, MEDLINE, and CINAHL were searched and studies were examined from their inception till October 2013. After title and abstract screening the relevant studies were included for this review. We found through this review that even though TENS and IFT are used in management of pain, there is limited amount of high quality research available in this area. Most of the studies lack methodological quality and have a low sample size. PMID:25709199

  14. Applications of Medium C-Band and High Resolution X-Band Multitemporal Interferometry in Landslide Investigations

    NASA Astrophysics Data System (ADS)

    Wasowski, J.; Bovenga, F.; Nutricato, R.; Nitti, D. O.; Chiaradia, M. T.

    2015-12-01

    With the increasing quantity and quality of the imagery available from a growing number of SAR satellites and the improved processing algorithms, multi-temporal interferometry (MTI) is expected to be commonly applied in landslide studies. MTI can now provide long-term (years), regular (weekly-monthly), precise (mm) measurements of ground displacements over large areas (thousands of km2), at medium (~20 m) to high (up to 1-3 m) spatial resolutions, combined with the possibility of multi-scale (regional to local) investigations, using the same series of radar images. We focus on the benefits as well as challenges of multisensor and multi-scale investigations by discussing MTI results regarding two landslide prone regions with distinctly different topographic, climatic and vegetation conditions (mountains in Central Albania and Southern Gansu, China), for which C-band (ERS or ENVISAT) and X-band COSMO-SkyMed (CSK) imagery was available (all in Stripmap descending mode). In both cases X-band MTI outperformed C-band MTI by providing more valuable information for the regional to local scale detection of slope deformations and landslide hazard assessment. This is related to the better spatial-temporal resolutions and more suitable incidence angles (40°-30° versus 23°) of CSK data While the use of medium resolution imagery may be appropriate and more cost-effective in reconnaissance or regional scale investigations, high resolution data could be preferentially exploited when focusing on urbanized landslides or potentially unstable slopes in urban/peri-urban areas, and slopes traversed by lifelines and other engineering structures.

  15. Characterisation of high temperature refractory ceramics for nuclear applications

    NASA Astrophysics Data System (ADS)

    Bottomley, P. D. W.; Wiss, Th; Janssen, A.; Cremer, B.; Thiele, H.; Manara, D.; Scheindlin, M.; Murray-Farthing, M.; Lajarge, P.; Menna, M.; Bouexière, D.; Rondinella, V. V.

    2012-03-01

    The ternary oxide ceramic system UO2-ZrO2-FeO is a refractory system that is of great relevance to the nuclear industry as it represents one of the main systems resulting from the interaction of the Zircaloy cladding, the UO2 fuel and the structural elements of a nuclear reactor. It is particularly the high temperature properties that require investigation; that is, when substantial overheating of the nuclear core occurs and interactions can lead to its degradation, melting and result in a severe nuclear accident. There has been much work on the UO2-ZrO2 system and also on the ternary system with FeO but there is still a need to examine 2 further aspects; firstly the effect of sub-oxidized systems, the UO2-Zr and FeO-Zr systems, and secondly the effect of Fe/Zr or Fe/U ratios on the melting point of the U-Zr-Fe oxide system. Samples of UO2-Zr and UO2-ZrO2-FeO were fabricated at ITU and then characterized by optical microscopy (OM) and X-ray diffraction to determine the ceramic's structure and verify the composition. Thereafter the samples are to be melted by laser flash heating and their liquidus and solidus temperatures determined by pyrometry. This programme is currently ongoing. The frozen samples, after testing, were then sectioned, polished and the molten zone micro-analytically examined by OM & SEM-EDS in order to determine its structure and composition and to compare with the existing phase diagrams. Examples of results from these systems will be given. Finally, a reacted Zr-FeO thermite mixture was examined, which had been used to generate high temperatures during tests of reactor melt-concrete interactions. The aim was to assess the reaction and estimate the heat generation from this novel technique. These results allow verification or improvement of the phase diagram and are of primary importance as input to models used to predict materials interactions in a severe nuclear accident.

  16. Metal-Coated Optical Fibers for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Zeakes, Jason; Murphy, Kent; Claus, Richard; Greene, Jonathan; Tran, Tuan

    1996-01-01

    A DC magnetron sputtering system has been used to actively coat optical fibers with hermetic metal coatings during the fiber draw process. Thin films of Inconel 625 have been deposited on optical fibers and annealed in air at 2000 F. Scanning electron microscopy and Auger electron microscopy have been used to investigate the morphology and composition of the films prior to and following thermal cycling. Issues to be addressed include film adhesion, other coating materials, and a discussion of additional applications for this novel technology.

  17. Application & testing of high temperature materials for solenoid coils

    SciTech Connect

    Sanchez, R.O.; Archer, W.E.; Zich, J.L.

    1997-08-01

    Sandia National Laboratories has designed and proven-in two new Solenoid coils for a highly-reliable electromechanical switch. Mil-Spec Magnetics Inc., Walnut CA manufactured the coils. The new design utilizes two new materials: Liquid Crystal Polymer (Vectra C130) for the bobbin and Thermal Barrier Silicone (VI-SIL V-658) for the encapsulant. The use of these two new materials solved most of the manufacturing problems inherent in the old Sandia design. The coils are easier to precision wind and more robust for handling, testing, and storage. The coils have some unique weapon related safety requirements. The most severe of these requirements is the 400{degrees}C, 1600 V test. The coils must not, and did not, produce any outgassing products to affect the voltage breakdown between contacts in the switch at these temperatures and voltages. Actual coils in switches were tested under these conditions. This paper covers the prove-in of this new coil design.

  18. Application of Flexible Micro Temperature Sensor in Oxidative Steam Reforming by a Methanol Micro Reformer

    PubMed Central

    Lee, Chi-Yuan; Lee, Shuo-Jen; Shen, Chia-Chieh; Yeh, Chuin-Tih; Chang, Chi-Chung; Lo, Yi-Man

    2011-01-01

    Advances in fuel cell applications reflect the ability of reformers to produce hydrogen. This work presents a flexible micro temperature sensor that is fabricated based on micro-electro-mechanical systems (MEMS) technology and integrated into a flat micro methanol reformer to observe the conditions inside that reformer. The micro temperature sensor has higher accuracy and sensitivity than a conventionally adopted thermocouple. Despite various micro temperature sensor applications, integrated micro reformers are still relatively new. This work proposes a novel method for integrating micro methanol reformers and micro temperature sensors, subsequently increasing the methanol conversion rate and the hydrogen production rate by varying the fuel supply rate and the water/methanol ratio. Importantly, the proposed micro temperature sensor adequately controls the interior temperature during oxidative steam reforming of methanol (OSRM), with the relevant parameters optimized as well. PMID:22319407

  19. Silicon Carbide-Based Hydrogen Gas Sensors for High-Temperature Applications

    PubMed Central

    Kim, Seongjeen; Choi, Jehoon; Jung, Minsoo; Joo, Sungjae; Kim, Sangchoel

    2013-01-01

    We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS) structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC) was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures. PMID:24113685

  20. Silicon carbide-based hydrogen gas sensors for high-temperature applications.

    PubMed

    Kim, Seongjeen; Choi, Jehoon; Jung, Minsoo; Joo, Sungjae; Kim, Sangchoel

    2013-01-01

    We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS) structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC) was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures. PMID:24113685

  1. Development and application of nonflammable, high-temperature beta fibers

    NASA Technical Reports Server (NTRS)

    Dawn, Frederic S.

    1989-01-01

    Recent advances in fiber technology have contributed to the success of the U.S. space program. The inorganic fiber Beta, developed as a result of efforts begun in the early 1960's and heightened following the January 27, 1967 Apollo fire is unique among inorganic and organic fibers. It has been developed into woven, nonwoven, knitted, braided, coated and printed structures. All of these were used extensively for the Apollo, Skylab, Apollo-Soyuz test project, space shuttle, Spacelab, and satellite programs. In addition to being used successfully in the space program, Beta fibers are being used commercially as firesafe fabrics in homes, hospitals, institutions, public buildings, aircraft, and public transportation, wherever total nonflammability is required. One of the most unique applications of the Beta composite structure is the roofing material for the 80,000-seat Detroit Lion's Silverdome and 5 square miles of the Jeddah International Airport in Saudi Arabia. This fiber has been successfully incorporated into 165 major public construction projects around the globe. The United States alone has used more than 12 million square yards of the material. Beta fiber has been used successfully to date and has a promising future with unlimited potential for both space and commercial application. Efforts are currently underway to improve Beta fiber to meet the requirements of extended service life for the Space Station Freedom, lunar outpost, and Mars exploration missions.

  2. Design and application of FBG strain experimental apparatus in high temperature

    NASA Astrophysics Data System (ADS)

    Xia, Zhongcheng; Liu, Yueming; Gao, Xiaoliang

    2014-09-01

    Fiber Bragg Grating (FBG) sensing technology has many applications, and it's widely used in detection of temperature, strain and etc. Now the application of FBG sensor is limited to the temperature below 200°C owing to the so called High Temperature Erasing Phenomenon. Strain detection over 200°C is still an engineering challenge since high temperature has a bad influence on the sensor, testing equipment and test data, etc, thus effective measurement apparatus are needed to ensure the accuracy of the measurement over 200°C, but there are no suitable FBG strain experimental apparatus in high temperature to date. In this paper a high temperature FBG strain experimental apparatus has been designed to detect the strain in high temperature. In order to verify working condition of the high temperature FBG strain, an application of FBG strain sensing experiment was given in this paper. The high temperature FBG strain sensor was installed in the apparatus, the internal temperature of experimental apparatus was controlled from -20 to 300°C accurately, and strain loading was given by the counterweight, then the data was recorded through electrical resistance strain measurement and optical sensing interrogator. Experimental data result shows that the high temperature FBG strain experimental apparatus can work properly over 200°C. The design of the high temperature FBG strain experimental apparatus are demonstrated suitable for high temperature strain gauges and FBG strain sensors , etc, which can work under the temperature of -20 ~ 300°C, the strain of -1500 ~ +1500μepsilon and the wavelength resolution of 1pm.

  3. Micro thermoindicators and optical-electronic temperature control for microfluidic applications

    NASA Astrophysics Data System (ADS)

    Liu, Liyu; Peng, Suili; Wen, Weijia; Sheng, Ping

    2007-08-01

    The authors report the design and implementation of sensing and control of local temperature in polydimethylsiloxane microfluidic reaction chip, based on the fabrication of a microtemperature sensor with thermochromic color bars and the associated optical and electronic feedback controls. The thermochromic color bar demonstrates easy and accurate local temperature monitoring. In combination with a microheater, this contactless microchip temperature control approach may have wide application potentials in microchemical and microbiological analyses.

  4. High Temperature Metal Hydrides as Heat Storage Materials for Solar and Related Applications

    PubMed Central

    Felderhoff, Michael; Bogdanović, Borislav

    2009-01-01

    For the continuous production of electricity with solar heat power plants the storage of heat at a temperature level around 400 °C is essential. High temperature metal hydrides offer high heat storage capacities around this temperature. Based on Mg-compounds, these hydrides are in principle low-cost materials with excellent cycling stability. Relevant properties of these hydrides and their possible applications as heat storage materials are described. PMID:19333448

  5. High temperature metal hydrides as heat storage materials for solar and related applications.

    PubMed

    Felderhoff, Michael; Bogdanović, Borislav

    2009-01-01

    For the continuous production of electricity with solar heat power plants the storage of heat at a temperature level around 400 degrees C is essential. High temperature metal hydrides offer high heat storage capacities around this temperature. Based on Mg-compounds, these hydrides are in principle low-cost materials with excellent cycling stability. Relevant properties of these hydrides and their possible applications as heat storage materials are described. PMID:19333448

  6. Dust Particle Growth and Application in Low Temperature Plasmas

    SciTech Connect

    Boufendi, L.

    2008-09-23

    Dust particle nucleation and growth has been widely studied these last fifteen years in different chemistries and experimental conditions. This phenomenon is correlated with various electrical changes at electrodes, including self-bias voltage and amplitudes of the various harmonics of current and voltage [1]. Some of these changes, such as the appearance of more resistive plasma impedance, are correctly attributed to loss of electrons in the bulk plasma to form negative molecular ions (e.g. SiH{sub 3}{sup -}) and more precisely charged nanoparticles. These changes were studied and correlated to the different phases on the dust particle formation. It is well known now that, in silane argon gas mixture discharges, in the first step of this particle formation we have formation of nanometer sized crystallites. These small entities accumulate and when their number density reaches a critical value, about 10{sup 11} to 10{sup 12} cm{sup -1}, they start to aggregate to form bigger particles. The different phases are well defined and determined thanks to the time evolution of the different electrical parameter changes. The purpose of this contribution is to compare different chemistries to highlight similarities and/or differences in order to establish possible universal dust particle growth mechanisms. The chemistries we studied concern SiH{sub 4}-Ar, CH{sub 4}, CH{sub 4}-N{sub 2} and Sn(CH{sub 3}){sub 4}[2]. We also refer to works performed in other laboratories in different discharge configurations [3]. Different applications have already developed or are foreseen for these nanoparticles. The first application concerns the inclusion of nanosized dust crystallites in an amorphous matrix in order to modify the optoelectronic and mechanical properties [4-5]. At the present time a very active research programs are devoted towards single electron devises where nanometer sized crystallites play a role of quantum dots. These nanoparticles can be produced in low pressure cold

  7. A Time-Temperature Transistor - An Application of Aging Dynamics

    NASA Astrophysics Data System (ADS)

    Kenning, Gregory

    Aging dynamics occur as systems far from thermodynamic equilibrium evolve towards equilibrium. We have produced a magnetic nanoparticle system composed of Co nanoparticles, which self-assemble during Co deposition on Sb. At a particular time in the formation of the nanoparticles, they are encased in a layer of Sb producing a system far from equilibrium. Magnetization vs. temperature measurements as well as Magnetic Force Microscopy (MFM) indicates that the nanoparticles initially have a large magnetic moment. We observe, as a function of time, an approximately 80% decay in the sample magnetization and an approximately 50% decay in the DC electrical resistivity. MFM suggests that the magnetization decay proceeds from the magnetic nanoparticles losing their net moments possibly due to spin rearrangement. Evidence also suggests that the initial magnetic moments, drive the Sb layer semiconducting. As the net moments of the magnetic nanoparticles decrease, the Sb reverts back to its semi-metal behavior with the accompanying decrease in the electrical resistivity. The magnetization and resistance decays follow the same Arrhenius type behavior. By varying the Co layer thickness, the Arrhenius parameters can be tuned. We have been able to tune the parameters making these materials excellent candidates for sensors for electronically monitoring the age and lifetime of perishable foods.

  8. Homogenization of daily temperature series: methods and applications

    NASA Astrophysics Data System (ADS)

    Toreti, Andrea; Kuglitsch, Franz G.; Xoplaki, Elena; Luterbacher, Juerg

    2010-05-01

    Data quality control and homogenization are essential tasks to be performed before any climate change analysis. They help identifying and removing (or reducing) the effects of non-climatic factors, as station relocation or instrumentation changes. Regarding the break point detection, a new procedure based on a Genetic Algorithm and Hidden Markov Models (GAHMM) is developed for changes in the mean and variance. Simulations confirm that GAHMM performs well in the identification of multiple shifts; moreover, it can be easily adapted to different initial assumptions on series and variables under investigation. As for the correction of inhomogeneities, an improved method, named Higher Order Moments for Autocorrelated Data (HOMAD), based on the well-known HOM method (Della-Marta and Wanner, 2006) has been implemented. It takes into account data autocorrelation both in the estimation of the regression function and cumulative distributions. GAHMM is applied together with the method of Caussinus and Mestre (2004) and RH-test (Wang et al., 2007) to a set of 246 daily series of maximum and minimum temperature recorded in the eastern Mediterranean from 1960 to 2006. The detected inhomogeneities are corrected with HOMAD.

  9. High Strength Aluminum Alloy For High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2005-01-01

    A cast article from an aluminum alloy has improved mechanical properties at elevated temperatures. The cast article has the following composition in weight percent: Silicon 6.0-25.0, Copper 5.0-8.0, Iron 0.05-1.2, Magnesium 0.5-1.5, Nickel 0.05-0.9, Manganese 0.05-1.2, Titanium 0.05-1.2, Zirconium 0.05-1.2, Vanadium 0.05-1.2, Zinc 0.05-0.9, Strontium 0.001-0.1, Phosphorus 0.001-0.1, and the balance is Aluminum, wherein the silicon-to-magnesium ratio is 10-25, and the copper-to-magnesium ratio is 4-15. The aluminum alloy contains a simultaneous dispersion of three types of Al3X compound particles (X=Ti, V, Zr) having a LI2 crystal structure, and their lattice parameters are coherent to the aluminum matrix lattice. A process for producing this cast article is also disclosed, as well as a metal matrix composite, which includes the aluminum alloy serving as a matrix containing up to about 60% by volume of a secondary filler material.

  10. A high-temperature furnace for applications in microgravity

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Technology in the area of material processing and crystal growth has been greatly furthered by research in microgravity environments. The role of efficient, lightweight furnaces with reliable performance is crucial in these experiments. A need exists for the development of a readily duplicated, high-temperature furnace satisfying stringent weight, volume, and power constraints. A furnace was designed and is referred to as the UAH SHIELD. Stringent physical and operating characteristics for the system were specified, including a maximum weight of 20 kg, a maximum power requirement of 60 W, and a volume of the furnace assembly, excluding the batteries, limited to half a Get-Away-Special canister. The UAH SHIELD furnace uses radiation shield and vacuum technology applied in the form of a series of concentric cylinders enclosed on either end with disks. Thermal testing of a furnace prototype was performed in addition to some thermal and structural analysis. Results indicate the need for spacing of the shields to accommodate the thermal expansion during furnace operation. In addition, a power dissipation of approximately 100 W and system weight of approximately 30 kg was found for the current design.

  11. PV Technology for Low Intensity, Low Temperature (LILT) Applications

    NASA Technical Reports Server (NTRS)

    Stella, Paul M.; Pool, Frederick S.; Nicolet, Marc A.; Iles, Peter A.

    1994-01-01

    As a result of the recent NASA emphasis on smaller, lower cost space missions, PV is now being considered for a number of missions operating at solar distances of 3 AU or greater. In the past, many of these missions would utilize an RTG (radioisotope thermoelectric generator). Historically, silicon solar cell behavior at these distances has been compromised by a number of mechanisms including shunting, nonohmic back contacts, and the 'broken knee' curve shape. The former two can usually be neglected for modern silicon cells, but the latter has not been eliminated. This problem has been identified with localized diffusion at the top contact/silicon interface which leads to structural changes at the local junction. This is believed to create a resistive metal-semiconductor-like (MSL) interface in parallel with the junction which results in the characteristic forms of the LILT (low intensity, low temperature) 'broken knee'. This paper discusses a TaSiN contact barrier that will prevent the MSL structure in the junction.

  12. (abstract) PV Technology for Low Intensity, Low Temperature (LILT) Applications

    NASA Technical Reports Server (NTRS)

    Stella, Paul M.; Pool, Frederick S.; Nicolet, Marc A.; Iles, Peter A.

    1994-01-01

    As a result of the recent NASA emphasis on smaller, lower cost space missions, PV is now being considered for a number of missions operating at solar distances of 3 AU or greater. In the past, many of these missions would utilize an RTG (radioisotope thermoelectric generator). Historically, silicon solar cell behavior at these distances has been compromised by a number of mechanisms including shunting, nonohmic back contacts, and the 'broken knee' curve shape. The former two can usually be neglected for modern silicon cells, but the latter has not been eliminated. This problem has been identified with localized diffusion at the top contact/silicon interface which leads to structural changes at the local junction. This is believed to create a resistive metal-semiconductor-like (MSL) interface in parallel with the junction which results in the characteristic forms of the LILT (low intensity, low temperature) 'broken knee'. This paper discusses a TaSiN contact barrier that will prevent the MSL structure in the junction.

  13. Ultra high temperature ceramics for hypersonic vehicle applications.

    SciTech Connect

    Tandon, Rajan; Dumm, Hans Peter; Corral, Erica L.; Loehman, Ronald E.; Kotula, Paul Gabriel

    2006-01-01

    HfB{sub 2} and ZrB{sub 2} are of interest for thermal protection materials because of favorable thermal stability, mechanical properties, and oxidation resistance. We have made dense diboride ceramics with 2 to 20 % SiC by hot pressing at 2000 C and 5000 psi. High-resolution transmission electron microscopy (TEM) shows very thin grain boundary phases that suggest liquid phase sintering. Fracture toughness measurements give RT values of 4 to 6 MPam{sup 1/2}. Four-pt flexure strengths measured in air up to 1450 C were as high as 450-500 MPa. Thermal diffusivities were measured to 2000 C for ZrB{sub 2} and HfB{sub 2} ceramics with SiC contents from 2 to 20%. Thermal conductivities were calculated from thermal diffusivities and measured heat capacities. Thermal diffusivities were modeled using different two-phase composite models. These materials exhibit excellent high temperature properties and are attractive for further development for thermal protection systems.

  14. Novel Gas Sensors for High-Temperature Fossil Fuel Applications

    SciTech Connect

    Palitha Jayaweera; Francis Tanzella

    2005-03-01

    SRI International (SRI) is developing ceramic-based microsensors to detect exhaust gases such as NO, NO{sub 2}, and CO in advanced combustion and gasification systems under this DOE NETL-sponsored research project. The sensors detect the electrochemical activity of the exhaust gas species on catalytic electrodes attached to a solid state electrolyte and are designed to operate at the high temperatures, elevated pressures, and corrosive environments typical of large power generation exhausts. The sensors can be easily integrated into online monitoring systems for active emission control. The ultimate objective is to develop sensors for multiple gas detection in a single package, along with data acquisition and control software and hardware, so that the information can be used for closed-loop control in novel advanced power generation systems. This report details the Phase I Proof-of-Concept, research activities performed from October 2003 to March 2005. SRI's research work includes synthesis of catalytic materials, sensor design and fabrication, software development, and demonstration of pulse voltammetric analysis of NO, NO{sub 2}, and CO gases on catalytic electrodes.

  15. Evaluation of a low temperature hardening Inorganic Phosphate Cement for high-temperature applications

    SciTech Connect

    Alshaaer, M.; Cuypers, H.; Mosselmans, G.; Rahier, H.; Wastiels, J.

    2011-01-15

    Phase and mechanical changes of Inorganic Phosphate Cement (IPC) are identified along with changes in macro properties as functions of temperature and time. In addition to amorphous phases, the presence of significant amounts of brushite and wollastonite in the reference IPC is confirmed using X-ray diffraction. The thermal behavior of IPC up to 1000 {sup o}C shows that contraction of the solid phase in IPC due to chemical transformations causes reduction in the volume of the material. Also the ongoing meta-stable calcium phosphate transformations and reactions over a long time contribute significantly to the phase instability of the material at ambient conditions. It is found that the strength of IPC increases with ageing at ambient conditions but the formation microcracks below 105 {sup o}C causes a sharp reduction in the mechanical performance of IPC. According to the results obtained by Mercury intrusion porosimetry, the pore system of the reference IPC is dominated by mesopores.

  16. Feed-thru flange is useful in vacuum applications to cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Yager, S. P.

    1966-01-01

    Feed-thru flange seals inner and outer walls of high vacuum test chambers. It is used in vacuum applications at both cryogenic and higher than cryogenic temperatures. A damaged flange can still be used for partial vacuum, noncryogenic applications in conjunction with an appropriate rubber seal.

  17. High temperature, radiation hardened electronics for application to nuclear power plants

    SciTech Connect

    Gover, J.E.

    1980-01-01

    Electronic circuits were developed and built at Sandia for many aerospace and energy systems applications. Among recent developments were high temperature electronics for geothermal well logging and radiation hardened electronics for a variety of aerospace applications. Sandia has also been active in technology transfer to commercial industry in both of these areas.

  18. BP neural network application on surface temperature measurement system based on colorimetry

    NASA Astrophysics Data System (ADS)

    Sun, Zhi-yuan; Cai, Sheng; Qiao, Yan-feng; Zhu, Wei

    2007-12-01

    Measurement of the features of infrared radiation is very important for the precaution and discrimination of missiles, and relevant research is worthy in military application. The measurement of target's surface temperature is the foundation of infrared radiation characteristics measurement. The principle and configuration of target's surface temperature measurement system based on colorimetry is introduced, the measurement model is deduced and the processes of temperature measurement are presented. Least-square method and back-propagation neural network method are both used to deal with the demarcating data. Compared with the least-square method, Back-propagation neural network has more advantages, such as high precision, good applicability and so on.

  19. Application of a serum-free medium for the growth of Vero cells and the production of reovirus.

    PubMed

    Butler, M; Burgener, A; Patrick, M; Berry, M; Moffatt, D; Huzel, N; Barnabé, N; Coombs, K

    2000-01-01

    Two strains of reovirus (serotype 1 Lang/TIL and serotype 3 Dearing/T3D) were propagated in Vero cells grown in stationary or agitated cultures in a serum-free medium, M-VSFM. Solid microcarriers (Cytodex-1) were used to support cell growth in agitated cultures with a normal doubling time of 25 h. Cell yields of 1 x 10(6) cells/mL were obtained from an inoculum of 2 x 10(5) cells/mL in 4 days in microcarrier cultures. The growth profile and cell yield was not significantly different from serum-supplemented cultures. The virus titer increased by 3-4 orders of magnitude over a culture period of 150 h. The maximum virus titer in stationary cultures reached >1 x 10(9) pfu/mL for both strains of reovirus in M-VSFM. M-VSFM also supported high viral yields in microcarrier cultures. Both the specific productivity and final viral yield was higher in M-VSFM than serum-supplemented cultures. The high viral productivity suggests that this is a suitable system for the production of reovirus as an oncolytic agent for human therapeutic use. PMID:11027181

  20. Application of fishmeal wastewater as a potential low-cost medium for lipid production by Lipomyces starkeyi HL.

    PubMed

    Huang, Lihui; Zhang, Bo; Gao, Baoyu; Sun, Guopeng

    2011-12-01

    Due to the high organic compounds and high salinity of fishmeal wastewater (FW), it was firstly used as a novel medium to produce microbial lipid in this paper. Fermentation of FW without any additives adding showed that the broth was appropriate for the growth of strain Lipomyces starkeyi HL; however, production of 5.34 g l(-1) of biomass containing 20.8% of lipid was not satisfied. In order to enhance the accumulation of lipid and cell growth, FW was supplemented with various concentrations of glucose; meanwhile, the influence of initial pH was investigated. Biomass and lipid yield on FW were markedly affected by glucose concentration and initial pH. The addition of 20 g l(-1) glucose at initial pH 4.0 got the best results: 17.6 g l(-1) of biomass, 2.7 g l(-1) of lipid yield, 91.2% of protein removal and 43.4% of the chemical oxygen demand removal. The variation of fatty acid composition upon time course in the cellular lipid on FW or a mixture of glucose and FW was further studied. PMID:22439586

  1. Fluorimetric detection of Sn(2+) ion in aqueous medium using Salicylaldehyde based nanoparticles and application to natural samples analysis.

    PubMed

    Patil, Kishor S; Mahajan, Prasad G; Patil, Shivajirao R

    2017-01-01

    The fluorescent 2-[(E)-(2-phenylhydrazinylidene)methyl]phenol nanoparticles (PHPNPs) were prepared by a simple reprecipitation method. The prepared PHPNPs examined by Dynamic Light Scattering show narrower particle size distribution having an average particle size of 93.3nm. The Scanning Electron Microphotograph shows distinct spherical shaped morphology of nanoparticles. The blue shift in UV-absorption and fluorescence spectra of PHPNPs with respect to corresponding spectra of PHP in acetone solution indicates H- aggregates and Aggregation Induced Enhanced Emission (AIEE) for nanoparticles. The nanoparticles show selective tendency towards the recognition of Sn(2+) ions by enhancing the fluorescence intensity preference to Cu(2+), Fe(3+), Fe(2+), Ni(2+), NH4(+), Ca(2+), Pb(2+), Hg(2+) and Zn(2+) ions, which actually seem to quench the fluorescence of nanoparticles. The studies on Langmuir adsorption plot, fluorescence lifetime of PHPNPs, DLS-Zeta sizer, UV-visible and fluorescence titration with and without Sn(2+) helped to propose a suitable mechanism of fluorescence enhancement of nanoparticles by Sn(2+) and their binding ability during complexation. The fluorescence enhancement effect of PHPNPs induced by Sn(2+) is further used to develop an analytical method for detection of Sn(2+) from aqueous medium in environmental samples. PMID:27423468

  2. Study on the activation of styrene-based shape memory polymer by medium-infrared laser light

    SciTech Connect

    Leng Jinsong; Yu Kai; Lan Xin; Zhang Dawei; Liu Yanju

    2010-03-15

    This paper demonstrates the feasibility of shape memory polymer (SMP) activation by medium-infrared laser light. Medium-infrared light is transmitted by an optical fiber embedded in the SMP matrix, and the shape recovery process and temperature distribution are recorded by an infrared camera. Light-induced SMP exhibits potential applications in biomedicines and flexible displays.

  3. Synthesis and characterization of a high-temperature, low-volatility phosphate additive for aerospace applications

    SciTech Connect

    Gschwender, L.J.; Snyder, C.E., Jr.; Fultz, G.W.; Chen, L.S. Dayton, University, OH )

    1991-11-01

    Tricresyl phosphate (TCP) is a widely used and effective antiwear additive for a variety of lubricants used in aerospace military applications. However, for a high-temperature gas turbine engine oil (GTO) application, volatility and thermo-oxidative stability limitations preclude the use of TCP. For this GTO application, high molecular weight, and thermally and thermo-oxidatively stable groups were incorporated into a phosphate-based additive. This paper describes the synthesis of this additive and its successful performance. 3 refs.

  4. Development of an advanced high-temperature fastener system for advanced aerospace vehicle application

    NASA Technical Reports Server (NTRS)

    Kull, F. R.

    1975-01-01

    The results of a program to develop a lightweight high temperature reusable fastening system for aerospace vehicle thermal protection system applications are documented. This feasibility program resulted in several fastener innovations which will meet the specific needs of the heat shield application. Three systems were designed from Hayes 188 alloy and tested by environmental exposure and residual mechanical properties. The designs include a clinch stud with a collar retainer, a weld stud with a split ring retainer, and a caged stud with a collar retainer. The results indicated that a lightweight, reusable, high temperature fastening system can be developed for aerospace vehicle application.

  5. Effect of repeated refrigerant spray applications using various carriers on pulpal temperature change.

    PubMed

    Garza, Christopher A; Vandewalle, Kraig S; Sabey, Kent A; Hamilton, Garrett J; Chong, Chol H

    2010-01-01

    This study sought to determine how repeated applications of a refrigerant spray on various cotton carriers affected the change in pulpal temperature. A thermocouple was placed at the roof of the pulp chamber of a human maxillary canine and connected to a thermometer logging at one-second intervals while the root was immersed in a water bath at 37 degrees C. Four different carrier types were used: large cotton pellets, small cotton pellets, cotton-tip applicators, and cotton rolls. Each carrier was sprayed with 1,1,1,2-tetrafluoroethane and placed on the crown for five seconds. Pulpal temperature change was recorded after each five second application of the same carrier to the tooth until a total of six consecutive sprays and applications of the carrier were applied. Each carrier group consisted of 10 performances of the six sets of readings (n = 10). The difference between baseline and the low temperature reading was calculated to determine the temperature change (in degrees C) in the pulp chamber per application. When the refrigerant spray was used, the large cotton pellet carrier generally produced the largest decrease in pulpal temperature at each repeated application compared to the other types of carriers. However, the same large cotton pellet should not be sprayed with the refrigerant more than two times before it is replaced. PMID:20478789

  6. Assessment of Various Low Temperature Electrolytes in Prototype Li-Ion Cells Developed for ESMD Applications

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; Whitcanack, L. D.

    2008-01-01

    Due to their attractive properties and proven success, Li-ion batteries have become identified as the battery chemistry of choice for a number of future NASA missions. A number of these applications would be greatly benefited by improved performance of Li-ion technology over a wider operating temperature range, especially at low temperatures, such as future ESMD missions. In many cases, these technology improvements may be mission enabling, and at the very least mission enhancing. In addition to aerospace applications, the DoE has interest in developing advanced Li-ion batteries that can operate over a wide temperature range to enable terrestrial HEV applications. Thus, our focus at JPL in recent years has been to extend the operating temperature range of Li-ion batteries, especially at low temperatures. To accomplish this, the main focus of the research has been devoted to developing improved lithium-ion conducting electrolytes. In the present paper, we would like to present some of the results we have obtained with six different ethylene carbonate-based electrolytes optimized for low temperature. In addition to investigating the behavior in experimental cells initially, the performance of these promising low temperature electrolytes was demonstrated in large capacity, aerospace quality Li-ion prototype cells, manufactured by Yardney Technical Products and Saft America, Inc. These cells were subjected to a number of performance tests, including discharge rate characterization, charge rate characterization, cycle life performance at various temperatures, and power characterization tests.

  7. Evaluation of high temperature dielectric films for high voltage power electronic applications

    NASA Technical Reports Server (NTRS)

    Suthar, J. L.; Laghari, J. R.

    1992-01-01

    Three high temperature films, polyimide, Teflon perfluoroalkoxy and poly-P-xylene, were evaluated for possible use in high voltage power electronic applications, such as in high energy density capacitors, cables and microelectronic circuits. The dielectric properties, including permittivity and dielectric loss, were obtained in the frequency range of 50 Hz to 100 kHz at temperatures up to 200 C. The dielectric strengths at 60 Hz were determined as a function of temperature to 250 C. Confocal laser microscopy was performed to diagnose for voids and microimperfections within the film structure. The results obtained indicate that all films evaluated are capable of maintaining their high voltage properties, with minimal degradation, at temperatures up to 200 C. However, above 200 C, they lose some of their electrical properties. These films may therefore become viable candidates for high voltage power electronic applications at high temperatures.

  8. Evaluation of ensemble forecast uncertainty using a new proper score: application to medium-range and seasonal forecasts

    NASA Astrophysics Data System (ADS)

    Christensen, Hannah; Moroz, Irene; Palmer, Tim

    2015-04-01

    Forecast verification is important across scientific disciplines as it provides a framework for evaluating the performance of a forecasting system. In the atmospheric sciences, probabilistic skill scores are often used for verification as they provide a way of unambiguously ranking the performance of different probabilistic forecasts. In order to be useful, a skill score must be proper -- it must encourage honesty in the forecaster, and reward forecasts which are reliable and which have good resolution. A new score, the Error-spread Score (ES), is proposed which is particularly suitable for evaluation of ensemble forecasts. It is formulated with respect to the moments of the forecast. The ES is confirmed to be a proper score, and is therefore sensitive to both resolution and reliability. The ES is tested on forecasts made using the Lorenz '96 system, and found to be useful for summarising the skill of the forecasts. The European Centre for Medium-Range Weather Forecasts (ECMWF) ensemble prediction system (EPS) is evaluated using the ES. Its performance is compared to a perfect statistical probabilistic forecast -- the ECMWF high resolution deterministic forecast dressed with the observed error distribution. This generates a forecast that is perfectly reliable if considered over all time, but which does not vary from day to day with the predictability of the atmospheric flow. The ES distinguishes between the dynamically reliable EPS forecasts and the statically reliable dressed deterministic forecasts. Other skill scores are tested and found to be comparatively insensitive to this desirable forecast quality. The ES is used to evaluate seasonal range ensemble forecasts made with the ECMWF System 4. The ensemble forecasts are found to be skilful when compared with climatological or persistence forecasts, though this skill is dependent on region and time of year.

  9. Cellulose binding domain assisted immobilization of lipase (GSlip-CBD) onto cellulosic nanogel: characterization and application in organic medium.

    PubMed

    Kumar, Ashok; Zhang, Shaowei; Wu, Gaobing; Wu, Cheng Chao; Chen, JunPeng; Baskaran, R; Liu, Ziduo

    2015-12-01

    A cbd gene was cloned into the C-terminal region of a lip gene from Geobacillus stearothermophilus. The native lipase (43.5 kDa) and CBD-Lip fusion protein (60.2 kDa) were purified to homogeneity by SDS-PAGE. A highly stable cellulosic nanogel was prepared by controlled hydrolysis of microcrystalline cellulose onto which the CBD-lip fusion protein was immobilized through bio-affinity based binding. The nanogel-bound lipase showed optimum activity at 55 °C, and it remains stable and active at pH 10-10.5. Furthermore, the immobilized lipase showed an over two-fold increase of relative activity in the presence of DMSO, isopropanol, isoamyl alcohol and n-butanol, but a mild activity decrease at a low concentration of methanol and ethanol. The immobilized biocatalyst retained ~50% activity after eight repetitive hydrolytic cycles. Enzyme kinetic studies of the immobilized lipase showed a 1.24 fold increase in Vmax and 5.25 fold increase in kcat towards p-NPP hydrolysis. Additionally, the nanogel bound lipase was tested to synthesize a biodiesel ester, ethyl oleate in DMSO. Kinetic analysis showed the km 100.5 ± 4.3 mmol and Vmax 0.19 ± 0.015 mmolmin(-1) at varied oleic acid concentration. Also, the values of km and Vmax at varying concentration of ethanol were observed to be 95.9 ± 13.9 mmol and 0.22 ± 0.013 mmolmin(-1) respectively. The maximum yield of ethyl oleate 111.2 ± 1.24 mM was obtained under optimized reaction conditions in organic medium. These results suggest that this immobilized biocatalyst can be used as an efficient tool for the biotransformation reactions on an industrial scale. PMID:26590897

  10. Thin film materials and devices for resistive temperature sensing applications

    NASA Astrophysics Data System (ADS)

    Basantani, Hitesh A.

    Thin films of vanadium oxide (VOx) and hydrogenated amorphous silicon (a-Si:H) are the two dominant material systems used in resistive infrared radiation detectors (microbolometers) for sensing long wave infrared (LWIR) wavelengths in the 8--14 microm range. Typical thin films of VO x (x < 2) currently used in the bolometer industry have a magnitude of temperature coefficient of resistance (TCR) between 2%/K -- 3%/K. In contrast, thin films of hydrogenated germanium (SiGe:H) have |TCR| between 3%/K to 4%/K. Devices made from either of these materials have resulted in similar device performance with NETD ≈ 25 mK. The performance of the microbolometers is limited by the electronic noise, especially 1/f noise. Therefore, regardless of the choice of bolometer sensing material and read out circuitry, manufacturers are constantly striving to reduce 1/f noise while simultaneously increasing TCR to give better signal to noise ratios in their bolometers and ultimately, better image quality with more thermal information to the end user. In this work, thin films of VOx and hydrogenated germanium (Ge:H), having TCR values > 4 %/K are investigated as potential candidates for higher sensitivity next generation of microbolometers. Thin films of VO x were deposited by Biased Target Ion Beam Deposition (BTIBD) (˜85 nm thick). Electrical characterization of lateral resistor structures showed resistivity ranging from 104 O--cm to 2.1 x 104 O--cm, TCR varying from --4%/K to --5%/K, normalized Hooge parameter (alphaH/n) of 5 x 10 -21 to 5 x 10-18 cm3. Thin films of Ge:H were deposited by plasma enhanced chemical vapor deposition (PECVD) by incorporating an increasing amount of crystal fraction in the growing thin films. Thin films of Ge:H having a mixed phase, amorphous + nanocrystalline, having a |TCR| > 6 %/K were deposited with resistivity < 2,300 O--cm and a normalized Hooge's parameter 'alphaH/n' < 2 x 10-20 cm3. Higher TCR materials are desired, however, such materials have

  11. Modelling of hydrothermal fluid circulation in a heterogeneous medium: Application to the Rainbow Vent site (Mid-Atlantic-Ridge, 36°14N)

    NASA Astrophysics Data System (ADS)

    Perez, F.; Mügler, C.; Jean-Baptiste, P.; Charlou, J. L.

    2012-04-01

    Hydrothermal activity at the axis of mid-ocean ridges is a key driver for energy and matter transfer from the interior of the Earth to the ocean floor. At mid-ocean ridges, seawater penetrates through the permeable young crust, warms at depth and exchanges chemicals with the surrounding rocks. This hot fluid focuses and flows upwards, then is expelled from the crust at hydrothermal vent sites in the form of black or white smokers completed by diffusive emissions. We developed a new numerical tool in the Cast3M software framework to model such hydrothermal circulations. Thermodynamic properties of one-phase pure water were calculated from the IAPWS formulation. This new numerical tool was validated on several test cases of convection in closed-top and open-top boxes. Simulations of hydrothermal circulation in a homogeneous-permeability porous medium also gave results in good agreement with already published simulations. We used this new numerical tool to construct a geometric and physical model configuration of the Rainbow Vent site at 36°14'N on the Mid-Atlantic Ridge. In this presentation, several configurations will be discussed, showing that high temperatures and high mass fluxes measured at the Rainbow site cannot be modelled with hydrothermal circulation in a homogeneous-permeability porous medium. We will show that these high values require the presence of a fault or a preferential pathway right below the venting site. We will propose and discuss a 2-D one-path model that allows us to simulate both high temperatures and high mass fluxes. This modelling of the hydrothermal circulation at the Rainbow site constitutes a first but necessary step to understand the origin of high concentrations of hydrogen issued from this ultramafic-hosted vent field.

  12. State-space approach for an infinite medium with a spherical cavity based upon two-temperature generalized thermoelasticity theory and fractional heat conduction

    NASA Astrophysics Data System (ADS)

    Zenkour, Ashraf M.; Abouelregal, Ahmed E.

    2014-02-01

    This paper is concerned with the determination of the thermoelastic displacement, stress, conductive temperature, and thermodynamic temperature in an infinite isotropic elastic body with a spherical cavity. A general solution to the problem based on the two-temperature generalized thermoelasticity theory (2TT) is introduced. The theory of thermal stresses based on the heat conduction equation with Caputo's time-fractional derivative of order α is used. Some special cases of coupled thermoelasticity and generalized thermoelasticity with one relaxation time are obtained. The general solution is provided by using Laplace's transform and state-space techniques. It is applied to a specific problem when the boundary of the cavity is subjected to thermomechanical loading (thermal shock). Some numerical analyses are carried out using Fourier's series expansion techniques. The computed results for thermoelastic stresses, conductive temperature, and thermodynamic temperature are shown graphically and the effects of two-temperature and fractional-order parameters are discussed.

  13. Application of Combined Sustained and Cyclic Loading Test Results to Alloy 617 Elevated Temperature Design Criteria

    SciTech Connect

    Wang, Yanli; Jetter, Robert I; Sham, Sam

    2014-08-25

    Alloy 617 is a reference structural material for very high temperature components of advanced-gas cooled reactors with outlet temperatures in the range of 900-950°C . In order for designers to be able to use Alloy 617 for these high temperature components, Alloy 617 has to be approved for use in Section III (the nuclear section) of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. A plan has been developed to submit a draft code for Alloy 617 to ASME Section III by 2015. However, the current rules in Subsection NH for the evaluation of strain limits and creep-fatigue damage using simplified methods based on elastic analysis have been deemed inappropriate for Alloy 617 at temperatures above 1200°F (650°C). The rationale for this exclusion is that at higher temperatures it is not feasible to decouple plasticity and creep deformation, which is the basis for the current simplified rules. This temperature, 1200 °F, is well below the temperature range of interest for this material in High Temperature Gas Cooled Reactor (HTGR) applications. The only current alternative is, thus, a full inelastic analysis which requires sophisticated material models which have been formulated but not yet verified. To address this issue, proposed code rules have been developed which are based on the use of elastic-perfectly plastic (EPP) analysis methods and which are expected to be applicable to very high temperatures.

  14. Integrated hydrological modelling of small- and medium-sized water storages with application to the upper Fengman Reservoir Basin of China

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Peng, Y.; Chu, J.; Shoemaker, C. A.

    2012-03-01

    Hydrological simulation in regions with a large number of water storages is difficult due to the inaccurate water storage data, including both topologic parameters and operational rules. To address this issue, this paper presents an improved version of SWAT2005 (Soil and Water Assessment Tool, version 2005) using the satellite-based dataset Landsat, an empirical storage classification method, and some empirical relationships to estimate water storage and release from the various levels of flow regulation facilities. The improved SWAT2005 is characterised by three features: (1) a realistic representation of the relationships between the water surface area and volume of each type of water storage, ranging from small-sized ponds for water flow regulation to large-sized and medium-sized reservoirs for water supply and hydropower generation; (2) water balance and transport through a network combining both sequential and parallel streams and storage links; and (3) calibrations for the physical parameters and the human interference parameters. Both the original and improved SWAT2005 are applied to the upper Fengman Reservoir Basin, and the results of these applications are compared. The improved SWAT2005 accurately models small- and medium-sized storages, indicating a significantly improved performance from that of the original model in reproducing streamflows.

  15. Spatio-temporal behavior of brightness temperature in Tel-Aviv and its application to air temperature monitoring.

    PubMed

    Pelta, Ran; Chudnovsky, A Alexandra; Schwartz, Joel

    2016-01-01

    This study applies remote sensing technology to assess and examine the spatial and temporal Brightness Temperature (BT) profile in the city of Tel-Aviv, Israel over the last 30 years using Landsat imagery. The location of warmest and coldest zones are constant over the studied period. Distinct diurnal and temporal BT behavior divide the city into four different segments. As an example of future application, we applied mixed regression models with daily random slopes to correlate Landsat BT data with monitored air temperature (Tair) measurements using 14 images for 1989-2014. Our preliminary results show a good model performance with R(2) = 0.81. Furthermore, based on the model's results, we analyzed the spatial profile of Tair within the study domain for representative days. PMID:26499933

  16. Electromagnetic induction in a conductive strip in a medium of contrasting conductivity: application to VLF and MT above molten dykes

    NASA Astrophysics Data System (ADS)

    Davis, Paul M.

    2014-11-01

    Very low frequency (VLF) electromagnetic waves that penetrate conductive magma-filled dykes generate secondary fields on the surface that can be used to invert for dyke properties. The model used for the interpretation calculates currents induced in a conductive strip by an inducing field that decays exponentially with depth due to the conductivity of the surrounding medium. The differential equations are integrated to give an inhomogeneous Fredholm equation of the second kind with a kernel consisting of a modified Bessel function of the second kind. Numerical methods are typically used to solve for the induced currents in the strip. In this paper, we apply a modified Galerkin-Chebyshev method, which involves separating the kernel into source and field spectra and integrating the source terms to obtain a matrix equation for the unknown coefficients. The incident wave is expressed as a Chebyshev series. The modified Bessel function is separated into a logarithmic singularity and a non-singular remainder, both of which are expanded in complex Chebyshev polynomials. The Chebyshev coefficients for the remainder are evaluated using a fast Fourier transform, while the logarithmic term and incident field have analytic series. The deconvolution then involves a matrix inversion. The results depend on the ratio of strip-size to skin-depth. For infinite skin-depth and a singular conductivity distribution given by τ_0 a/√{a^2 - z^2 } (where τ0 is the conductance, a is the half-length and z the distance from the centre), Parker gives an analytic solution. We present a similar analytic series solution for the finite skin-depth case, where the size to skin depth ratio is small. Results are presented for different ratios of size to skin depth that can be compared with numerical solutions. We compare full-space and half-space solutions. A fit of the model to VLF data taken above a magma filled dykes in Hawaii and Mt Etna demonstrates that while properties such as depth to top

  17. Application of mucilage from Dicerocaryum eriocarpum plant as biosorption medium in the removal of selected heavy metal ions.

    PubMed

    Jones, Bassey O; John, Odiyo O; Luke, Chimuka; Ochieng, Aoyi; Bassey, Bridget J

    2016-07-15

    The ability of mucilage from Dicerocaryum eriocarpum (DE) plant to act as biosorption medium in the removal of metals ions from aqueous solution was investigated. Functional groups present in the mucilage were identified using Fourier transform infrared spectroscopy (FTIR). Mucilage was modified with sodium and potassium chlorides. This was aimed at assessing the biosorption efficiency of modified mucilage: potassium mucilage (PCE) and sodium mucilage (SCE) and comparing it with non-modified deionised water mucilage (DCE) in the uptake of metal ions. FTIR results showed that the functional groups providing the active sites in PCE and SCE and DCE include: carboxyl, hydroxyl and carbonyl groups. The chloride used in the modification of the mucilage did not introduce new functional groups but increased the intensity of the already existing functional groups in the mucilage. Results from biosorption experiment showed that DE mucilage displays good binding affinity with metals ions [Zn(II), Cd(II) Ni(II), Cr(III) and Fe(II)] in the aqueous solution. Increase in the aqueous solution pH, metal ions initial concentration and mucilage concentration increased the biosorption efficiency of DE mucilage. The maximum contact time varied with each species of metal ions. Optimum pH for [Zn(II), Cd(II) Ni(II) and Fe(II)] occurred at pH 4 and pH 6 for Cr(III). Kinetic models result fitted well to pseudo-second-order with a coefficient values of R(2) = 1 for Cd(II), Ni(II), Cr(III), Fe(II) and R(2) = 0.9974 for Zn(II). Biosorption isotherms conforms best with Freundlich model for all the metal ions with correlation factors of 0.9994, 0.9987, 0.9554, 0.9621 and 0.937 for Zn(II), Ni(II), Fe(II), Cr(III) and Cd(II), respectively. Biosorption capacity of DE mucilage was 0.010, 2.387, 4.902, 0688 and 0.125 for Zn(II), Cr(III), Fe(II), Cd(II) and Ni(II) respectively. The modified mucilage was found to be highly efficient in the removal of metal ions than the unmodified mucilage. PMID

  18. ENSYSTROB - Design, manufacturing and test of a 3-phase resistive fault current limiter based on coated conductors for medium voltage application

    NASA Astrophysics Data System (ADS)

    Elschner, S.; Kudymow, A.; Brand, J.; Fink, S.; Goldacker, W.; Grilli, F.; Noe, M.; Vojenciak, M.; Hobl, A.; Bludau, M.; Jänke, C.; Krämer, S.; Bock, J.

    2012-11-01

    Within the German project ENSYSTROB a 3-phase resistive fault current limiter for medium voltage applications (12 kV, 533 Arms) was designed, built, tested and installed in the grid for a one year’s field test. The superconducting modules are made of YBCO coated conductors and replace the modules of an already successfully tested limiter on the basis of BSCCO 2212 bulk material. The components are multifilar spirals equipped with pairs of 12 mm wide YBCO tapes. The single components were characterized with respect to critical current, AC losses and limitation behavior under all possible operation conditions. The finally mounted limiter was successfully tested with respect to high voltage and limitation according to the standards of the customer. It is now installed and operating in its field test location. Finally we give a first comparison of both materials with respect to the different operational aspects.

  19. THE ATTENUATED RADON TRANSFORM: APPLICATION TO SINGLE-PHOTON EMISSION COMPUTED TOMOGRAPHY IN THE PRESENCE OF A VARIABLE ATTENUATING MEDIUM

    SciTech Connect

    Gullberg, Grant T.

    1980-03-01

    The properties of the attenuated Radon transform and its application to single-photon emission computed tomography (ECT) are analyzed in detail. In nuclear medicine and biological research, the objective of ECT is to describe quantitatively the position and strengths of internal sources of injected radiopharmaceuticals and radionuclides where the attenuation between the sources and detector is unknown. The problem is mathematically and practically quite different from well-known methods in transmission computed tomography (TCT) where only the attenuation is unknown. A mathematical structure using function theory and the theory of linear operators on Hilbert spaces is developed to better understand the spectral properties of the attenuated Radon transform. The continuous attenuated Radon transform is reduced to a matrix operator for discrete angular and lateral sampling, and the reconstruction problem reduces to a system of linear equations. For variable attenuation coefficients frequently found in imaging internal organs, the numerical methods developed in this paper involve iterative techniques of performing the generalized inverse. Its application to nuclear medicine is demonstrated by reconstructions of transverse sections of the brain, heart, and liver.

  20. Investigation of Neutron Detector Response to Varying Temperature and Water Content for Geothermal Applications

    SciTech Connect

    Akkurt, Hatice

    2010-01-01

    Nuclear logging techniques have been used for oil well logging applications for decades. The basic principle is to use a neutron and/or photon source and neutron and photon detectors for characterization purposes. Although the technology has matured, it is not directly applicable to geothermal logging due to even more challenging environmental conditions, both in terms of temperature and pressure. For geothermal logging, the operating temperature can go up to 376 C for depths up to 10,000 km. In this paper, the preliminary computational results for thermal neutron detector response for varying temperature and water content for geothermal applications are presented. In this summary, preliminary results for neutron detector response for varying formation temperature and water content are presented. The analysis is performed for a steady state source (AmBe) and time dependent source (PNG) in pulsed mode. The computational results show significant sensitivity to water content as well as temperature changes for both steady state and time dependent measurements. As expected, the most significant change is due to the temperature change for S({alpha}, {beta}) nuclear data instead of individual isotope cross sections for the formation. Clearly, this is partially because of the fact that strong absorbers (i.e., chlorine) are not taken into account for the analysis at this time. The computational analysis was performed using the temperature dependent data in the ENDF/B-VII libraries, supplied with MCNP. Currently, the data for intermediate temperatures are being generated using NJOY and validated. A series of measurements are planned to validate the computational results. Further measurements are planned to determine the neutron and photon detector response as a function of temperature. The tests will be performed for temperatures up to 400 C.

  1. Enrichment of denitrifying methanotrophic bacteria for application after direct low-temperature anaerobic sewage treatment.

    PubMed

    Kampman, Christel; Hendrickx, Tim L G; Luesken, Francisca A; van Alen, Theo A; Op den Camp, Huub J M; Jetten, Mike S M; Zeeman, Grietje; Buisman, Cees J N; Temmink, Hardy

    2012-08-15

    Despite many advantages of anaerobic sewage treatment over conventional activated sludge treatment, it has not yet been applied in temperate zones. This is especially because effluent from low-temperature anaerobic treatment contains nitrogen and dissolved methane. The presence of nitrogen and methane offers the opportunity to develop a reactor in which methane is used as electron donor for denitrification. Such a reactor could be used in a new concept for low-temperature anaerobic sewage treatment, consisting of a UASB-digester system, a reactor for denitrification coupled to anaerobic methane oxidation, and a nitritation reactor. In the present study denitrifying methanotrophic bacteria similar to 'Candidatus Methylomirabilis oxyfera' were enriched. Maximum volumetric nitrite consumption rates were 33.5 mg NO(2)(-)-N/Ld (using synthetic medium) and 37.8 mg NO(2)(-)-N/Ld (using medium containing effluent from a sewage treatment plant), which are similar to the maximum rate reported so far. Though the goal was to increase the rates, in both reactors, after reaching these maximum rates, volumetric nitrite consumption rates decreased in time. Results indicate biomass washout may have significantly decelerated enrichment. Therefore, to obtain higher volumetric consumption rates, further research should focus on systems with complete biomass retention. PMID:22657102

  2. Optoacoustic imaging of absorbing objects in a turbid medium: ultimate sensitivity and application to breast cancer diagnostics

    SciTech Connect

    Khokhlova, Tatiana D.; Pelivanov, Ivan M.; Kozhushko, Victor V.; Zharinov, Alexei N.; Solomatin, Vladimir S.; Karabutov, Alexander A

    2007-01-10

    One of the major medical applications of optoacoustic (OA) tomography is in the diagnostics of early-stage breast cancer. A numerical approach was developed to characterize the following parameters of an OA imaging system: resolution, maximum depth at which the tumor can be detected, and image contrast. The parameters of the 64-element focused array transducer were obtained. The results of numerical modeling were compared with known analytical solutions and further validated by phantom experiments. The OA images of a3 mm piece of bovine liver immersed in diluted milk at various depths were obtained. Based on the results of modeling, a signal filtering algorithm for OA image contrast enhancement has been proposed.

  3. Microstructure and Corrosion Behavior of Hf-40 Wt Pct Ti Alloy in Nitric Acid Medium for Reprocessing Applications

    NASA Astrophysics Data System (ADS)

    Jayaraj, J.; Ravi, K. R.; Mallika, C.; Kamachi Mudali, U.

    2016-09-01

    The Hf-40 wt pct Ti (Hf-Ti) alloy was developed for neutron poison application in the spent nuclear fuel reprocessing plant. The furnace-cooled Hf-Ti sample exhibited the microstructure comprising equiaxed-α, lamellar-α, and feathery-α. The water-quenched Hf-Ti sample confirmed the presence of lath and internally twinned martensite. In comparison to the furnace-cooled sample, low corrosion current density and passivation current density values obtained for the water-quenched Hf-Ti in 6 M HNO3 at 298 K (25 °C) indicated better passivation ability. The martensitic structure exhibited high hardness (660 HV) and negligible corrosion rate in 6 M nitric acid at 298 K (25 °C). X-ray photoelectron spectroscopic (XPS) analysis confirmed that passivation behavior of this alloy was due to the protective passive film composed of TiO2 and HfO2.

  4. Microstructure and Corrosion Behavior of Hf-40 Wt Pct Ti Alloy in Nitric Acid Medium for Reprocessing Applications

    NASA Astrophysics Data System (ADS)

    Jayaraj, J.; Ravi, K. R.; Mallika, C.; Kamachi Mudali, U.

    2016-06-01

    The Hf-40 wt pct Ti (Hf-Ti) alloy was developed for neutron poison application in the spent nuclear fuel reprocessing plant. The furnace-cooled Hf-Ti sample exhibited the microstructure comprising equiaxed-α, lamellar-α, and feathery-α. The water-quenched Hf-Ti sample confirmed the presence of lath and internally twinned martensite. In comparison to the furnace-cooled sample, low corrosion current density and passivation current density values obtained for the water-quenched Hf-Ti in 6 M HNO3 at 298 K (25 °C) indicated better passivation ability. The martensitic structure exhibited high hardness (660 HV) and negligible corrosion rate in 6 M nitric acid at 298 K (25 °C). X-ray photoelectron spectroscopic (XPS) analysis confirmed that passivation behavior of this alloy was due to the protective passive film composed of TiO2 and HfO2.

  5. Optoacoustic imaging of absorbing objects in a turbid medium: ultimate sensitivity and application to breast cancer diagnostics

    NASA Astrophysics Data System (ADS)

    Khokhlova, Tatiana D.; Pelivanov, Ivan M.; Kozhushko, Victor V.; Zharinov, Alexei N.; Solomatin, Vladimir S.; Karabutov, Alexander A.

    2007-01-01

    One of the major medical applications of optoacoustic (OA) tomography is in the diagnostics of early-stage breast cancer. A numerical approach was developed to characterize the following parameters of an OA imaging system: resolution, maximum depth at which the tumor can be detected, and image contrast. The parameters of the 64-element focused array transducer were obtained. The results of numerical modeling were compared with known analytical solutions and further validated by phantom experiments. The OA images of a 3 mm piece of bovine liver immersed in diluted milk at various depths were obtained. Based on the results of modeling, a signal filtering algorithm for OA image contrast enhancement has been proposed.

  6. Thermographic-phosphor temperature measurements: Commercial and defense-related applications

    SciTech Connect

    Noel, B.W.; Turley, W.D.; Allison, S.W.

    1994-06-01

    This paper is a review of a diverse set of applications of the thermographic-phosphor (TP) method for measuring temperatures remotely. The TP method is useful in hostile and/or inaccessible environments where no other known method works. It is highly accurate, nonintrusive, durable, conceptually simple, covers an unprecedented temperature range (0 K to >1200 K), can measure temperature at a single point or over an entire surface, and can make static, steady-state, or very high speed dynamic measurements. The TP method can also be used to make leadless, remotely interrogated heat-flux gauges that can nonintrusively measure spatial distributions of heat flux over arbitrarily large areas with high resolution. The applications described include measurements in gas centrifuges, motors, variable-area ejectors, rotors and stators in gas turbines, and others. The authors also briefly discuss heat-flux gauges and their applications.

  7. A new soil-temperature module for SWAT application in regions with seasonal snow cover

    NASA Astrophysics Data System (ADS)

    Qi, Junyu; Li, Sheng; Li, Qiang; Xing, Zisheng; Bourque, Charles P.-A.; Meng, Fan-Rui

    2016-07-01

    Accurate estimates of soil temperature are important for quantifying hydrological and biological processes in hydrological models. Soil temperature predictions in the widely used Soil and Water Assessment Tool (SWAT) have large prediction errors when applied to regions with significant snow cover during winter. In this study, a new physically-based soil-temperature module is developed as an alternative to the empirical soil-temperature module currently used in SWAT. The physically-based module ​simulates soil temperature in different soil layers as a result of energy transfer between the atmosphere and soil (or snow) interface. The modified version of SWAT with the new soil-temperature module in place, introduces only three new parameters over the original soil-temperature module. Both the original and new soil-temperature modules are tested against field data from the Black Brook Watershed, a small watershed in Atlantic Canada. The results indicate that both versions of soil-temperature module ​are able to provide acceptable predictions of temperature in different layers of the soil during non-winter seasons. However, the original module severely underestimates soil temperatures in winter (within -10 to -20 °C), while the new module produces results that are more consistent with field measurements (within -2 to 2 °C). In addition, unlike its counterpart, the new module ​is able to simulate freeze-thaw cycles in the soil profile. Ice-water content variations in winter are reasonably simulated by the new module for different snow cover scenarios. In general, modified-SWAT improves prediction accuracy on baseflow discharge compared with the original-SWAT, due to improved estimates of soil temperature during winter. The new physically-based soil-temperature module has greatly improved the ability of SWAT to predict soil temperatures under seasonal snow cover, which is essential to the application of the model in regions like Atlantic Canada.

  8. Ceramic fibers for matrix composites in high-temperature engine applications

    PubMed

    Baldus; Jansen; Sporn

    1999-07-30

    High-temperature engine applications have been limited by the performance of metal alloys and carbide fiber composites at elevated temperatures. Random inorganic networks composed of silicon, boron, nitrogen, and carbon represent a novel class of ceramics with outstanding durability at elevated temperatures. SiBN(3)C was synthesized by pyrolysis of a preceramic N-methylpolyborosilazane made from the single-source precursor Cl(3)Si-NH-BCl(2). The polymer can be processed to a green fiber by melt-spinning, which then undergoes an intermediate curing step and successive pyrolysis. The ceramic fibers, which are presently produced on a semitechnical scale, combine several desired properties relevant for an application in fiber-reinforced ceramic composites: thermal stability, mechanical strength, high-temperature creep resistivity, low density, and stability against oxidation or molten silicon. PMID:10426985

  9. [The Clinical Application Status and Development Trends of Hydrogen Peroxide Low Temperature Plasma Sterilizers].

    PubMed

    Zhuang, Min; Zheng, Yunxin; Chen, Ying; Hou, Bin; Xu, Zitian

    2016-01-01

    The hydrogen peroxide low temperature plasma sterilization technology solved the problems of thermo-sensitive materials' disinfection and sterilization based on its development and unique characteristics. This paper introduced the researches of clinical application quality control, and showed the hydrogen peroxide low temperature plasma sterilizers were being widely used in hospitals and highly recognized. According to the clinical data and the literatures of the domestic equipment in preliminary application, it could be concluded that the technology maturity of domestic hydrogen peroxide low temperature plasma sterilizers was in a high level. The advantages of using domestic hydrogen peroxide low temperature plasma sterilizers to do disinfection and sterilization included lower cost, safer, faster and non-toxic, etc. Also the management system should be improved and the clinical staff should master the technical essentials, obey the procedures strictly, verify periodically and offer full monitoring to upgrade the quality of sterilization. PMID:27197500

  10. Temperature feedback-controlled photothermal treatment with diffusing applicator: theoretical and experimental evaluations

    PubMed Central

    Nguyen, Trung Hau; Park, Suhyun; Hlaing, Kyu Kyu; Kang, Hyun Wook

    2016-01-01

    To minimize thermal injury, the current study evaluated the real-time temperature monitoring with a proportional-integrative-derivative (PID) controller during 980-nm photothermal treatment with a radially-diffusing applicator. Both simulations and experiments demonstrated comparable thermal behaviors in temperature distribution and the degree of irreversible tissue denaturation. The PID-controlled application constantly maintained the pre-determined temperature of 353 K (steady-state error = < 1 K). Due to constant energy delivery, coagulation volumes linearly increased up to 1.04 ± 0.02 cm3 with irradiation time. Integration of temperature feedback with diffuser-assisted photothermal treatments can provide a feasible therapeutic modality to treat pancreatic tumors in an effective manner. PMID:27231632

  11. Characterization of piezoelectric materials for simultaneous strain and temperature sensing for ultra-low frequency applications

    NASA Astrophysics Data System (ADS)

    Nouroz Islam, Mohammad; Seethaler, Rudolf; Shahria Alam, M.

    2015-08-01

    Piezoelectric materials are used extensively in a number of sensing applications ranging from aerospace industries to medical diagnostics. Piezoelectric materials generate charge when they are subjected to strain. However, since measuring charge is difficult at low frequencies, traditional piezoelectric sensors are limited to dynamic applications. In this research an alternative technique is proposed to determine static strain that relies upon the measurement of piezoelectric capacitance and resistance using piezoelectric sensors. To demonstrate the validity of this approach, the capacitance and resistance of a piezoelectric patch sensor was characterized for a wide range of strain and temperature. The study shows that the piezoelectric capacitance is sensitive to both strain and temperature while the resistance is mostly dependent on the temperature variation. The findings can be implemented to obtain thermally compensated static strain from piezoelectric sensors, which does not require an additional temperature sensor.

  12. Principles of application of high temperature superconductors to electromagnetic launch technology

    SciTech Connect

    Oberly, C.E.; Kozlowski, G. ); Gooden, C.E. ); Lenard, R.X. ); Sarkar, A.K.; Maartense, I. . Research Inst.); Ho, J.C. )

    1991-01-01

    Many recent advances in the performance of bulk high temperature superconductors (HTSC) now permit conductor and magnet development at practical magnetic fields to be pursued for high current applications such as electromagnetic launchers (EML). While early hopes for a superconductor critical temperature (T{sub c}) approaching room temperature have not been fulfilled, numerous HTSC with T{sub c} between 60K and 125K exist which can be successfully processed. Some of these HTSC are well enough understood that small conductors and coils may be fabricated for operation near 20K. Numerous physics, magnetic flux mechanics, materials processing and structural support issues remain for resolution before large scale coils made of HTSC can be operated at high energy storage density at temperatures well above 20K. This paper describes the authors' recent results on properties and materials processing of HTSC and their relation to EML applications technology.

  13. Temperature feedback-controlled photothermal treatment with diffusing applicator: theoretical and experimental evaluations.

    PubMed

    Nguyen, Trung Hau; Park, Suhyun; Hlaing, Kyu Kyu; Kang, Hyun Wook

    2016-05-01

    To minimize thermal injury, the current study evaluated the real-time temperature monitoring with a proportional-integrative-derivative (PID) controller during 980-nm photothermal treatment with a radially-diffusing applicator. Both simulations and experiments demonstrated comparable thermal behaviors in temperature distribution and the degree of irreversible tissue denaturation. The PID-controlled application constantly maintained the pre-determined temperature of 353 K (steady-state error = < 1 K). Due to constant energy delivery, coagulation volumes linearly increased up to 1.04 ± 0.02 cm(3) with irradiation time. Integration of temperature feedback with diffuser-assisted photothermal treatments can provide a feasible therapeutic modality to treat pancreatic tumors in an effective manner. PMID:27231632

  14. Electrical Properties of Materials for Elevated Temperature Resistance Strain Gage Application. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Lei, Jih-Fen

    1987-01-01

    The objective was to study the electrical resistances of materials that are potentially useful as resistance strain gages at 1000 C. Transition metal carbides and nitrides, boron carbide and silicon carbide were selected for the experimental phase of this research. Due to their low temperature coefficient of resistance and good stability, TiC, ZrC, B sub 4 C and beta-SiC are suggested as good candidates for high temperature resistance strain gage applications.

  15. Thermal regime and temperature stresses in bodies during thermoradiational heating. [application of perturbation method

    NASA Technical Reports Server (NTRS)

    Chistopyanova, N. V.; Chumakov, V. L.

    1974-01-01

    An approach is developed to the application of the perturbation method for the solution of problems with essential external nonlinearities, based on identification in the boundary condition of a small nonlinear complex which is considered a perturbing function. The solutions obtained in the first approximation with error of 1 to 2% in calculating the unsteady temperature fields are then used to determine the temperature stresses and deformations in solid bodies of classical form.

  16. Application of modern control theory to temperature control of the MBE system

    NASA Astrophysics Data System (ADS)

    Ishikawa, Takuya; Chan, Yuen Chuen; Nakano, Yoshiaki; Tada, Kunio

    1990-03-01

    The setup of an MBE control system without PID controllers, whereby one microprocessor manages all the Knudsen cells directly, is reported. The model-following algorithm is applied to the temperature control of the Knudsen cells, and improved dynamic response of the cell temperature is obtained compared with that obtained by the conventional PID algorithm. An application of the model-following algorithm to device fabrication is demonstrated.

  17. A New Approach to Joining of Silicon Carbide-Based Materials for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay

    1998-01-01

    Ceramic joining is recognized as one of the enabling technologies for the application of silicon carbide-based materials in a number of high temperature applications. An affordable, robust technique for the joining of silicon carbide-based ceramics has been developed. This technique is capable of producing joints with tailorable thickness and composition. Microstructure and mechanical properties of reaction formed joints in a reaction bonded silicon carbide have been reported. These joints maintain their mechanical strengths at high temperatures (up to 1350 C) in air. This technique is capable of joining large and complex shaped ceramic components.

  18. Applications of high-temperature powder metal aluminum alloys to small gas turbines

    NASA Technical Reports Server (NTRS)

    Millan, P. P., Jr.

    1982-01-01

    A program aimed at the development of advanced powder-metallurgy (PM) aluminum alloys for high-temperature applications up to 650 F using the concepts of rapid solidification and mechanical alloying is discussed. In particular, application of rapidly solidified PM aluminum alloys to centrifugal compressor impellers, currently used in auxiliary power units for both military and commercial aircraft and potentially for advanced automotive gas turbine engines, is examined. It is shown that substitution of high-temperature aluminum for titanium alloy impellers operating in the 360-650 F range provides significant savings in material and machining costs and results in reduced component weight, and consequently, reduced rotating group inertia requirements.

  19. Biomedical Applications of Low Temperature Atmospheric Pressure Plasmas to Cancerous Cell Treatment and Tooth Bleaching

    NASA Astrophysics Data System (ADS)

    Lee, Jae Koo; Kim, Myoung Soo; Byun, June Ho; Kim, Kyong Tai; Kim, Gyoo Cheon; Park, Gan Young

    2011-08-01

    Low temperature atmospheric pressure plasmas have attracted great interests and they have been widely applied to biomedical applications to interact with living tissues, cells, and bacteria due to their non-thermal property. This paper reviews the biomedical applications of low temperature atmospheric pressure plasmas to cancerous cell treatment and tooth bleaching. Gold nanoparticles conjugated with cancer-specific antibodies have been introduced to cancerous cells to enhance selective killing of cells, and the mechanism of cell apoptosis induced by plasma has been investigated. Tooth exposed to helium plasma jet with hydrogen peroxide has become brighter and the productions of hydroxyl radicals from hydrogen peroxide have been enhanced by plasma exposure.

  20. Thick sputtered tantalum coatings for high-temperature energy conversion applications

    SciTech Connect

    Stelmakh, Veronika Peykov, Daniel; Chan, Walker R.; Senkevich, Jay J.; Joannopoulos, John D.; Soljačić, Marin; Celanovic, Ivan; Castillo, Robert; Coulter, Kent; Wei, Ronghua

    2015-11-15

    Thick sputtered tantalum (Ta) coatings on polished Inconel were investigated as a potential replacement for bulk refractory metal substrates used for high-temperature emitters and absorbers in thermophotovoltaic energy conversion applications. In these applications, high-temperature stability and high reflectance of the surface in the infrared wavelength range are critical in order to sustain operational temperatures and reduce losses due to waste heat. The reflectance of the coatings (8 and 30 μm) was characterized with a conformal protective hafnia layer as-deposited and after one hour anneals at 700, 900, and 1100 °C. To further understand the high-temperature performance of the coatings, the microstructural evolution was investigated as a function of annealing temperature. X-ray diffraction was used to analyze the texture and residual stress in the coatings at four reflections (220, 310, 222, and 321), as-deposited and after anneal. No significant changes in roughness, reflectance, or stress were observed. No delamination or cracking occurred, even after annealing the coatings at 1100 °C. Overall, the results of this study suggest that the thick Ta coatings are a promising alternative to bulk substrates and pave the way for a relatively low-cost and easily integrated platform for nanostructured devices in high-temperature energy conversion applications.

  1. A Chandra Study of the Lobe/Interstellar Medium Interactions around the Inner Radio Lobes of Centaurus A: Constraints on the Temperature Structure and Transport Processes

    NASA Astrophysics Data System (ADS)

    Kraft, R. P.; Nulsen, P. E. J.; Birkinshaw, M.; Worrall, D. M.; Penna, R. F.; Forman, W. R.; Hardcastle, M. J.; Jones, C.; Murray, S. S.

    2007-08-01

    We present results from deeper Chandra observations of the southwest radio lobe of Centaurus A, first described by Kraft and coworkers. We find that the sharp X-ray surface brightness discontinuity extends around ~75% of the periphery of the radio lobe and detect significant temperature jumps in the brightest regions of this discontinuity nearest to the nucleus. This demonstrates that this discontinuity is indeed a strong shock that is the result of an overpressure that has built up in the entire lobe over time. In addition, we demonstrate that if the mean free path for ions to transfer energy and momentum to the electrons behind the shock is as large as the Spitzer value, the electron and proton temperatures will not have equilibrated along the southwest boundary of the radio lobe where the shock is strongest. Thus, the proton temperature of the shocked gas could be considerably larger than the observed electron temperature, and the total energy of the outburst correspondingly larger as well. We investigate this using a simple one-dimensional shock model for a two-fluid (proton/electron) plasma. We find that for the thermodynamic parameters of the Cen A shock the electron temperature rises rapidly from ~0.29 keV (the temperature of the ambient ISM) to ~3.5 keV, at which point heating from the protons is balanced by adiabatic losses. The proton and electron temperatures do not equilibrate in a timescale less than the age of the lobe. We note that the measured electron temperature of similar features in other nearby powerful radio galaxies in poor environments may considerably underestimate the strength and velocity of the shock.

  2. Estimation of effective temperatures in quantum annealers for sampling applications: A case study with possible applications in deep learning

    NASA Astrophysics Data System (ADS)

    Benedetti, Marcello; Realpe-Gómez, John; Biswas, Rupak; Perdomo-Ortiz, Alejandro

    2016-08-01

    An increase in the efficiency of sampling from Boltzmann distributions would have a significant impact on deep learning and other machine-learning applications. Recently, quantum annealers have been proposed as a potential candidate to speed up this task, but several limitations still bar these state-of-the-art technologies from being used effectively. One of the main limitations is that, while the device may indeed sample from a Boltzmann-like distribution, quantum dynamical arguments suggest it will do so with an instance-dependent effective temperature, different from its physical temperature. Unless this unknown temperature can be unveiled, it might not be possible to effectively use a quantum annealer for Boltzmann sampling. In this work, we propose a strategy to overcome this challenge with a simple effective-temperature estimation algorithm. We provide a systematic study assessing the impact of the effective temperatures in the learning of a special class of a restricted Boltzmann machine embedded on quantum hardware, which can serve as a building block for deep-learning architectures. We also provide a comparison to k -step contrastive divergence (CD-k ) with k up to 100. Although assuming a suitable fixed effective temperature also allows us to outperform one-step contrastive divergence (CD-1), only when using an instance-dependent effective temperature do we find a performance close to that of CD-100 for the case studied here.

  3. 27 CFR 19.914 - Medium plants.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Medium plants. 19.914... OF THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Distilled Spirits For Fuel Use Permits § 19.914 Medium plants. Any person wishing to establish a medium plant shall make application for and obtain...

  4. Mechanical Properties and Microstructural Characterization of Particulate Reinforced Diboride Composites for High Temperature Leading Edge Applications

    NASA Technical Reports Server (NTRS)

    Ellerby, Donald T.; Johnson, Sylvia M.; Bull, Jeff; Laub, Bernie; Reuther, James; Kinney, David; Kontinos, Dean; Beckman, Sarah; Stuffle, Kevin; Cull, A. D.; Arnold, Jim (Technical Monitor)

    2001-01-01

    Previous work on refractory diboride composites has shown that these systems have the potential for use in high temperature leading edge applications for reusable reentry vehicles. Experiments in reentry environments have shown that these materials have multiple use temperatures greater than 1900 C. The work to be discussed focuses on three compositions: HfB2/SiC, ZrB2/SiC, and ZrB2/C/SiC. These composites have been hot pressed and their mechanical properties measured at room and elevated temperatures. Extensive microstructural characterization has been conducted on polished cross sections and the fracture surfaces have been examined to determine their failure origins.

  5. Stainless steel component with compressed fiber Bragg grating for high temperature sensing applications

    NASA Astrophysics Data System (ADS)

    Jinesh, Mathew; MacPherson, William N.; Hand, Duncan P.; Maier, Robert R. J.

    2016-05-01

    A smart metal component having the potential for high temperature strain sensing capability is reported. The stainless steel (SS316) structure is made by selective laser melting (SLM). A fiber Bragg grating (FBG) is embedded in to a 3D printed U-groove by high temperature brazing using a silver based alloy, achieving an axial FBG compression of 13 millistrain at room temperature. Initial results shows that the test component can be used for up to 700°C for sensing applications.

  6. AMSAHTS 1990: Advances in Materials Science and Applications of High Temperature Superconductors

    NASA Technical Reports Server (NTRS)

    Bennett, Larry H. (Editor); Flom, Yury (Editor); Moorjani, Kishin (Editor)

    1991-01-01

    This publication is comprised of abstracts for oral and poster presentations scheduled for AMSAHTS '90. The conference focused on understanding high temperature superconductivity with special emphasis on materials issues and applications. AMSAHTS 90, highlighted the state of the art in fundamental understanding of the nature of high-Tc superconductivity (HTSC) as well as the chemistry, structure, properties, processing and stability of HTSC oxides. As a special feature of the conference, space applications of HTSC were discussed by NASA and Navy specialists.

  7. Application of terrestrial 'structure-from-motion' photogrammetry on a medium-size Arctic valley glacier: potential, accuracy and limitations

    NASA Astrophysics Data System (ADS)

    Hynek, Bernhard; Binder, Daniel; Boffi, Geo; Schöner, Wolfgang; Verhoeven, Geert

    2014-05-01

    Terrestrial photogrammetry was the standard method for mapping high mountain terrain in the early days of mountain cartography, until it was replaced by aerial photogrammetry and airborne laser scanning. Modern low-price digital single-lens reflex (DSLR) cameras and highly automatic and cheap digital computer vision software with automatic image matching and multiview-stereo routines suggest the rebirth of terrestrial photogrammetry, especially in remote regions, where airborne surveying methods are expensive due to high flight costs. Terrestrial photogrammetry and modern automated image matching is widely used in geodesy, however, its application in glaciology is still rare, especially for surveying ice bodies at the scale of some km², which is typical for valley glaciers. In August 2013 a terrestrial photogrammetric survey was carried out on Freya Glacier, a 6km² valley glacier next to Zackenberg Research Station in NE-Greenland, where a detailed glacier mass balance monitoring was initiated during the last IPY. Photos with a consumer grade digital camera (Nikon D7100) were taken from the ridges surrounding the glacier. To create a digital elevation model, the photos were processed with the software photoscan. A set of ~100 dGPS surveyed ground control points on the glacier surface was used to georeference and validate the final DEM. Aim of this study was to produce a high resolution and high accuracy DEM of the actual surface topography of the Freya glacier catchment with a novel approach and to explore the potential of modern low-cost terrestrial photogrammetry combined with state-of-the-art automated image matching and multiview-stereo routines for glacier monitoring and to communicate this powerful and cheap method within the environmental research and glacier monitoring community.

  8. A Review of Heating and Temperature Control in Microfluidic Systems: Techniques and Applications

    PubMed Central

    Miralles, Vincent; Huerre, Axel; Malloggi, Florent; Jullien, Marie-Caroline

    2013-01-01

    This review presents an overview of the different techniques developed over the last decade to regulate the temperature within microfluidic systems. A variety of different approaches has been adopted, from external heating sources to Joule heating, microwaves or the use of lasers to cite just a few examples. The scope of the technical solutions developed to date is impressive and encompasses for instance temperature ramp rates ranging from 0.1 to 2,000 °C/s leading to homogeneous temperatures from −3 °C to 120 °C, and constant gradients from 6 to 40 °C/mm with a fair degree of accuracy. We also examine some recent strategies developed for applications such as digital microfluidics, where integration of a heating source to generate a temperature gradient offers control of a key parameter, without necessarily requiring great accuracy. Conversely, Temperature Gradient Focusing requires high accuracy in order to control both the concentration and separation of charged species. In addition, the Polymerase Chain Reaction requires both accuracy (homogeneous temperature) and integration to carry out demanding heating cycles. The spectrum of applications requiring temperature regulation is growing rapidly with increasingly important implications for the physical, chemical and biotechnological sectors, depending on the relevant heating technique. PMID:26835667

  9. Application of time-temperature-stress superposition on creep of wood-plastic composites

    NASA Astrophysics Data System (ADS)

    Chang, Feng-Cheng; Lam, Frank; Kadla, John F.

    2013-08-01

    Time-temperature-stress superposition principle (TTSSP) was widely applied in studies of viscoelastic properties of materials. It involves shifting curves at various conditions to construct master curves. To extend the application of this principle, a temperature-stress hybrid shift factor and a modified Williams-Landel-Ferry (WLF) equation that incorporated variables of stress and temperature for the shift factor fitting were studied. A wood-plastic composite (WPC) was selected as the test subject to conduct a series of short-term creep tests. The results indicate that the WPC were rheologically simple materials and merely a horizontal shift was needed for the time-temperature superposition, whereas vertical shifting would be needed for time-stress superposition. The shift factor was independent of the stress for horizontal shifts in time-temperature superposition. In addition, the temperature- and stress-shift factors used to construct master curves were well fitted with the WLF equation. Furthermore, the parameters of the modified WLF equation were also successfully calibrated. The application of this method and equation can be extended to curve shifting that involves the effects of both temperature and stress simultaneously.

  10. High-speed surface temperature measurements on plasma facing materials for fusion applications

    SciTech Connect

    Araki, M.; Kobayashi, M.

    1996-01-01

    For the lifetime evaluation of plasma facing materials in fusion experimental machines, it is essential to investigate their surface behavior and their temperature responses during an off-normal event such as the plasma disruptions. An infrared thermometer with a sampling speed as fast as 1{times}10{sup {minus}6} s/data, namely, the high-speed infrared thermometer (HSIR), has been developed by the National Research Laboratory of Metrology in Japan. To evaluate an applicability of the newly developed HSIR on the surface temperature measurement of plasma facing materials, high heat flux beam irradiation experiments have been performed with three different materials under the surface heat fluxes up to 170 MW/m{sup 2} for 0.04 s in a hydrogen ion beam test facility at the Japan Atomic Energy Research Institute. As for the results, HSIR can be applicable for measuring the surface temperature responses of the armor tile materials with a little modification. It is also confirmed that surface temperatures measured with the HSIR thermometer show good agreement with the analytical results for stainless steel and carbon based materials at a temperature range of up to 2500{degree}C. However, for aluminum the HSIR could measure the temperature of the high dense vapor cloud which was produced during the heating due to lower melting temperature. Based on the result, a multichannel arrayed HSIR thermometer has been designed and fabricated. {copyright} {ital 1996 American Institute of Physics.}

  11. Investigations on AlN/sapphire piezoelectric bilayer structure for high-temperature SAW applications.

    PubMed

    Aubert, Thierry; Elmazria, Omar; Assouar, Badreddine; Blampain, Eloi; Hamdan, Ahmad; Genève, Damien; Weber, Sylvain

    2012-05-01

    This paper explores the possibility of using AlN/sapphire piezoelectric bilayer structures for high-temperature SAW applications. To determine the temperature stability of AlN, homemade AlN/sapphire samples are annealed in air atmosphere for 2 to 20 h at temperatures from 700 to 1000°C. Ex situ X-ray diffraction measurements reveal that the microstructure of the thin film is not affected by temperatures below 1000°C. Ellipsometry and secondary ion mass spectroscopy investigations attest that AlN/sapphire is reliable up to 700°C. Beyond this temperature, both methods indicate ongoing surface oxidation of AlN. Additionally, Pt/Ta and Al interdigital transducers are patterned on the surface of the AlN film. The resulting SAW devices are characterized up to 500°C and 300°C, respectively, showing reliable frequency response and a large, quasi-constant temperature sensitivity, with a first-order temperature coefficient of frequency around -75 ppm/°C. Between room temperature and 300°C, both electromechanical coupling coefficient K(2) and propagation losses increase, so the evolution of delay lines' insertion losses with temperature strongly depends on the length of the propagation path. PMID:22622985

  12. Combination of transurethral and interstitial ultrasound applicators for high-temperature prostate thermal therapy.

    PubMed

    Diederich, C J; Nau, W H; Burdette, E C; Bustany, I S; Deardorff, D L; Stauffer, P R

    2000-01-01

    The purpose of this study was to determine the feasibility of using a transurethral ultrasound applicator in combination with implantable ultrasound applicators for inducing thermal coagulation and necrosis of localized cancer lesions or benign disease within the prostate gland. The potential to treat target zones in the anterior and lateral portions of the prostate with the angularly directive transurethral applicator, while simultaneously treating regions of extracapsular extension and zones in the posterior prostate with the directive implantable applicators in combination with a rectal cooling bolus, is evaluated. Biothermal computer simulations, acoustic characterizations, and in vivo thermal dosimetry experiments with canine prostates were used to evaluate the performance of each applicator type and combinations thereof. Simulations have demonstrated that transurethral applicators with 180-270 degrees acoustic active zones can direct therapeutic heating patterns to the anterior and lateral prostate, implantable needles can isolate heating to the posterior gland while avoiding rectal tissue, and that the combination of applicators can be used to produce conformal heating to the whole gland. Single implantable applicators (1.8 mm OD x 10 mm long, approximately 180 degrees active sector, approximately 7 MHz, direct-coupled type) produced directional thermal lesions within in vivo prostate, with temperatures >50 degrees C extending more than 10 mm radially after 10-15 min. Combination of interstitial applicators (1-2) and a transurethral applicator (3-2.5 mm OD x 6 mm long, approximately 180 degrees active sector, 6.8 MHz, 6 mm OD delivery catheter) produced conforming temperature distributions (48-85 degrees C) and zones of acute thermal damage within 15 min. The preliminary results of this investigation demonstrate that implantable directional ultrasound applicators, in combination with a transurethral ultrasound applicator, have the potential to provide

  13. Very high temperature measurements: Applications to nuclear reactor safety tests; Mesures des tres hautes temperatures: Applications a des essais de surete des reacteurs nucleaires

    SciTech Connect

    Parga, Clemente-Jose

    2013-09-27

    This PhD dissertation focuses on the improvement of very high temperature thermometry (1100 deg. C to 2480 deg. C), with special emphasis on the application to the field of nuclear reactor safety and severe accident research. Two main projects were undertaken to achieve this objective: - The development, testing and transposition of high-temperature fixed point (HTFP) metal-carbon eutectic cells, from metrology laboratory precision (±0.001 deg. C) to applied research with a reasonable degradation of uncertainties (±3-5 deg. C). - The corrosion study and metallurgical characterization of Type-C thermocouple (service temp. 2300 deg. C) prospective sheath material was undertaken to extend the survivability of TCs used for molten metallic/oxide corium thermometry (below 2000 deg. C)

  14. Modification of a pulsed 14-MeV fast neutron generator to a medium-energy ion accelerator for TOF-RBS application

    NASA Astrophysics Data System (ADS)

    Junphong, P.; Suwannakachorn, D.; Yu, L. D.; Singkarat, S.

    2011-12-01

    The first drift-tube neutron generator in Thailand, developed during 1980s under the support by the International Atomic Energy Agency (IAEA), was a 150 kV deuteron accelerator-based 14 MeV fast neutron generator. The accelerator was featured by a nanosecond pulsing system consisting of a beam chopper in combination with a beam buncher. Following the rapid development of ion beam technology and increasing needs for materials applications in the laboratory, the accelerator has been upgraded and modified to a large extent into a medium-energy ion-accelerator for time-of-flight Rutherford backscattering spectrometry (TOF-RBS) applications. The modification of the accelerator included the changing of the ion source, the accelerating tube and the mass-analyzing magnet, the upgrading of the pulsing system, and the installation of a TOF-RBS detecting system. The new accelerator is capable of supplying a 400-keV He-ion beam with ns-pulses for nano-layered materials analysis. This paper provides technical details of the modification.

  15. Application of Gamma code coupled with turbomachinery models for high temperature gas-cooled reactors

    SciTech Connect

    Chang Oh

    2008-02-01

    The very high-temperature gas-cooled reactor (VHTR) is envisioned as a single- or dual-purpose reactor for electricity and hydrogen generation. The concept has average coolant temperatures above 9000C and operational fuel temperatures above 12500C. The concept provides the potential for increased energy conversion efficiency and for high-temperature process heat application in addition to power generation. While all the High Temperature Gas Cooled Reactor (HTGR) concepts have sufficiently high temperature to support process heat applications, such as coal gasification, desalination or cogenerative processes, the VHTR’s higher temperatures allow broader applications, including thermochemical hydrogen production. However, the very high temperatures of this reactor concept can be detrimental to safety if a loss-ofcoolant accident (LOCA) occurs. Following the loss of coolant through the break and coolant depressurization, air will enter the core through the break by molecular diffusion and ultimately by natural convection, leading to oxidation of the in-core graphite structure and fuel. The oxidation will accelerate heatup of the reactor core and the release of a toxic gas, CO, and fission products. Thus, without any effective countermeasures, a pipe break may lead to significant fuel damage and fission product release. Prior to the start of this Korean/United States collaboration, no computer codes were available that had been sufficiently developed and validated to reliably simulate a LOCA in the VHTR. Therefore, we have worked for the past three years on developing and validating advanced computational methods for simulating LOCAs in a VHTR. GAMMA code is being developed to implement turbomachinery models in the power conversion unit (PCU) and ultimately models associated with the hydrogen plant. Some preliminary results will be described in this paper.

  16. An Application of Trimethylsilyl Derivatives with Temperature Programmed Gas Chromatography to the Senior Analytical Laboratory.

    ERIC Educational Resources Information Center

    Kelter, Paul B.; Carr, James D.

    1983-01-01

    Describes an experiment designed to teach temperature programed gas chromatography (TPGC) techniques and importance of derivatizing many classes of substrated to be separated. Includes equipment needed, procedures for making trimethylsilyl derivatives, applications, sample calculations, and typical results. Procedure required one, three-hour…

  17. Use of a Multiwavelength Pyrometer in Several Elevated Temperature Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Ng, Daniel; Fralick, Gustave

    2001-01-01

    A multiwavelength pyrometer was developed for applications unique to aerospace environments. It was shown to be a useful and versatile technique for measuring temperature, even when the emissivity is unknown. It has also been used to measure the surface temperatures of ceramic zircomia thermal barrier coatings and alumina. The close agreement between pyrometer and thin film thermocouple temperatures provided an independent check. Other applications of the multiwavelength pyrometer are simultaneous surface and bulk temperature measurements of a transparent material, and combustion gas temperature measurement using a special probe interfaced to the multiwavelength pyrometer via an optical fiber. The multiwavelength pyrometer determined temperature by transforming the radiation spectrum in a broad wavelength region to produce a straight line (in a certain spectral region), whose intercept in the vertical axis gives the temperature. Implicit in a two-color pyrometer is the assumption of wavelength independent emissivity. Though the two data points of a two-color pyrometer similarly processed would result immediately in a similar straight line to give the unknown temperature, the two-color pyrometer lacks the greater data redundancy of the multiwavelength pyrometer, which enables it to do so with improved accuracy. It also confirms that emissivity is indeed wavelength independent, as evidenced by a multitude of the data lying on a simple straight line. The multiwavelength pyrometer was also used to study the optical transmission properties of a nanostructured material from which a quadratic exponential functional frequency dependence of its spectral transmission was determined. Finally, by operating the multiwavelength pyrometer in a very wide field of view mode, the surface temperature distribution of a large hot surface was obtained through measurement of just a single radiation spectrum.

  18. Use of a multiwavelength pyrometer in several elevated temperature aerospace applications

    NASA Astrophysics Data System (ADS)

    Ng, Daniel; Fralick, Gustave

    2001-02-01

    A multiwavelength pyrometer was developed for applications unique to aerospace environments. It was shown to be a useful and versatile technique for measuring temperature, even when the emissivity is unknown. It has also been used to measure the surface temperatures of ceramic zircornia thermal barrier coatings and alumina. The close agreement between pyrometer and thin film thermocouple temperatures provided an independent check. Other applications of the multiwavelength pyrometer are simultaneous surface and bulk temperature measurements of a transparent material, and combustion gas temperature measurement using a special probe interfaced to the multiwavelength pyrometer via an optical fiber. The multiwavelength pyrometer determined temperature by transforming the radiation spectrum in a broad wavelength region to produce a straight line (in a certain spectral region), whose intercept in the vertical axis gives the temperature. Implicit in a two-color pyrometer is the assumption of wavelength independent emissivity. Though the two data points of a two-color pyrometer similarly processed would result immediately in a similar straight line to give the unknown temperature, the two-color pyrometer lacks the greater data redundancy of the multiwavelength pyrometer, which enables it to do so with improved accuracy. It also confirms that emissivity is indeed wavelength independent, as evidenced by a multitude of the data lying on a simple straight line. The multiwavelength pyrometer was also used to study the optical transmission properties of a nanostructured material from which a quadratic exponential functional frequency dependence of its spectral transmission was determined. Finally, by operating the multiwavelength pyrometer in a very wide field of view mode, the surface temperature distribution of a large hot surface was obtained through measurement of just a single radiation spectrum.

  19. Automation of temperature control for large-array microwave surface applicators.

    PubMed

    Zhou, L; Fessenden, P

    1993-01-01

    An adaptive temperature control system has been developed for the microstrip antenna array applicators used for large area superficial hyperthermia. A recursive algorithm which allows rapid power updating even for large antenna arrays and accounts for coupling between neighbouring antennas has been developed, based on a first-order difference equation model. Surface temperatures from the centre of each antenna element are the primary feedback information. Also used are temperatures from additional surface probes placed within the treatment field to protect locations vulnerable to excessive temperatures. In addition, temperatures at depth are observed by mappers and utilized to restrain power to reduce treatment-related complications. Experiments on a tissue-equivalent phantom capable of dynamic differential cooling have successfully verified this temperature control system. The results with the 25 (5 x 5) antenna array have demonstrated that during dynamic water cooling changes and other experimentally simulated disturbances, the controlled temperatures converge to desired temperature patterns with a precision close to the resolution of the thermometry system (0.1 degree C). PMID:8515149

  20. Application of fuzzy logic to the control of wind tunnel settling chamber temperature

    NASA Technical Reports Server (NTRS)

    Gwaltney, David A.; Humphreys, Gregory L.

    1994-01-01

    The application of Fuzzy Logic Controllers (FLC's) to the control of nonlinear processes, typically controlled by a human operator, is a topic of much study. Recent application of a microprocessor-based FLC to the control of temperature processes in several wind tunnels has proven to be very successful. The control of temperature processes in the wind tunnels requires the ability to monitor temperature feedback from several points and to accommodate varying operating conditions in the wind tunnels. The FLC has an intuitive and easily configurable structure which incorporates the flexibility required to have such an ability. The design and implementation of the FLC is presented along with process data from the wind tunnels under automatic control.