WorldWideScience

Sample records for high temperature effects

  1. High Pressure and Temperature Effects in Polymers

    Science.gov (United States)

    Bucknall, David; Arrighi, Valeria; Johnston, Kim; Condie, Iain

    Elastomers are widely exploited as the basis for seals in gas and fluid pipelines. The underlying behaviour of these elastomer at the high pressure, elevated temperatures they experience in operation is poorly understood. Consequently, the duty cycle of these materials is often deliberately limited to a few hours, and in order to prevent failure, production is stopped in order to change the seals in critical joints. The result is significant time lost due to bringing down production to change the seals as well as knock on financial costs. In order to address the fundamental nature of the elastomers at their intended operating conditions, we are studying the gas permeation behaviour of hydrogenated natural butyl rubber (HNBR) and fluorinated elastomers (FKM) at a high pressure and elevated temperature. We have developed a pressure system that permits gas permeation studies at gas pressures of up to 5000 psi and operating temperatures up to 150° C. In this paper, we will discuss the nature of the permeation behaviour at these extreme operating conditions, and how this relates to the changes in the polymer structure. We will also discuss the use of graphene-polymer thin layer coatings to modify the gas permeation behaviour of the elastomers.

  2. Microstructural Evolution and Mechanical Behavior of High Temperature Solders: Effects of High Temperature Aging

    Science.gov (United States)

    Hasnine, M.; Tolla, B.; Vahora, N.

    2017-12-01

    This paper explores the effects of aging on the mechanical behavior, microstructure evolution and IMC formation on different surface finishes of two high temperature solders, Sn-5 wt.% Ag and Sn-5 wt.% Sb. High temperature aging showed significant degradation of Sn-5 wt.% Ag solder hardness (34%) while aging has little effect on Sn-5 wt.% Sb solder. Sn-5 wt.% Ag experienced rapid grain growth as well as the coarsening of particles during aging. Sn-5 wt.% Sb showed a stable microstructure due to solid solution strengthening and the stable nature of SnSb precipitates. The increase of intermetallic compound (IMC) thickness during aging follows a parabolic relationship with time. Regression analysis (time exponent, n) indicated that IMC growth kinetics is controlled by a diffusion mechanism. The results have important implications in the selection of high temperature solders used in high temperature applications.

  3. Effect of microstructure on the high temperature strength of nitride ...

    Indian Academy of Sciences (India)

    The effect of these parameters on room temperature and high temperature strength of the composite up to 1300°C in ambient condition were studied. The high temperature flexural strength of the composite of all compositions increased at 1200 and 1300°C because of oxidation of Si3N4 phase and blunting crack front.

  4. Effect of High Temperature on Properties of Glass Concrete

    Directory of Open Access Journals (Sweden)

    Wang Wei Chien

    2017-01-01

    Full Text Available In this study, the concrete is mixed with glass fibers which are 0.5%, 1.0% and 1.5% of cement weight and 0.6 cm long. The effect of fiber addition level on the compressive strength, bending strength and residual compressive strength and thermal conductivity after heating of concrete is discussed. The test results show that an appropriate addition of glass fiber to the concrete at room temperature is favorable for the compressive strength. A low addition of relatively short glass fiber has insignificant effect on the bending strength. However, the adverse effect on the bending strength will increase if the addition level is too high. The addition of glass fiber can improve the loss of concrete strength under the effect of high temperature not exceeding 500°C, and a relatively high compressive strength remains under the effect of high temperature not exceeding 800°C. The high temperature can reduce the thermal conductivity of glass concrete, and the higher the addition level of glass fiber is, the lower is the thermal conductivity. Keywords: Glass fiber, concrete, heating, thermal conductivity

  5. Effect of microstructure on the high temperature strength of nitride ...

    Indian Academy of Sciences (India)

    Unknown

    Effect of microstructure on the high temperature strength of nitride bonded silicon carbide composite. J RAKSHIT and P K DAS*. Central Glass and Ceramic Research Institute, Kolkata 700 032, India. MS received 15 March 2002; revised 3 August 2002. Abstract. Four compositions of nitride bonded SiC were fabricated with ...

  6. Quantitative Temperature Dependence of Longitudinal Spin Seebeck Effect at High Temperatures

    Directory of Open Access Journals (Sweden)

    Ken-ichi Uchida

    2014-11-01

    Full Text Available We report temperature-dependent measurements of longitudinal spin Seebeck effects (LSSEs in Pt/Y_{3}Fe_{5}O_{12} (YIG/Pt systems in a high temperature range from room temperature to above the Curie temperature of YIG. The experimental results show that the magnitude of the LSSE voltage in the Pt/YIG/Pt systems rapidly decreases with increasing the temperature and disappears above the Curie temperature. The critical exponent of the LSSE voltage in the Pt/YIG/Pt systems at the Curie temperature is estimated to be 3, which is much greater than that for the magnetization curve of YIG. This difference highlights the fact that the mechanism of the LSSE cannot be explained in terms of simple static magnetic properties in YIG.

  7. Effects of the high temperatures of cows in nursing.

    Directory of Open Access Journals (Sweden)

    Erasmo G. Hurtado Sosa

    2014-06-01

    Full Text Available To determine the physiologic answer to the high temperatures in the cow’s milkmaids in different moments of the postparto in the municipality of Fomento, 15 cows were evaluated during a period of 61 days in a warm and humid climate. The answer indicators to the heat were: Rectal temperature, cutaneous temperature, temperature of the milk, breathing frequency and heart frequency, the statistic analysis was carried out with the help of the statistical programs STATGRAPHICS Bonus 5.1 for Windows ® 2000 and the processor of data Excel, Office 2007, they were carried out correlation tests and regression, to analyze the effects from the animal answer to the heat for the suitable groups, it was carried out a variance analysis with a factorial design, in series of time. The most sensitive indicators of animal answer were the TR and the FR, the group postpartum smaller than 30 the most sensitive to the high temperatures, prevailing a situation of danger for the livestock and differences under the conditions of comfort for the cows among the morning (ITH 59.63 and the afternoon (ITH 90.72, being more favorable for the cluster the Indicator of morning comfort.

  8. Effective kinetic theory for high temperature gauge theories

    Science.gov (United States)

    Arnold, Peter B.; Moore, Guy D.; Yaffe, Laurence G.

    2003-01-01

    Quasiparticle dynamics in relativistic plasmas associated with hot, weakly-coupled gauge theories (such as QCD at asymptotically high temperature T) can be described by an effective kinetic theory, valid on sufficiently large time and distance scales. The appropriate Boltzmann equations depend on effective scattering rates for various types of collisions that can occur in the plasma. The resulting effective kinetic theory may be used to evaluate observables which are dominantly sensitive to the dynamics of typical ultrarelativistic excitations. This includes transport coefficients (viscosities and diffusion constants) and energy loss rates. In this paper, we show how to formulate effective Boltzmann equations which will be adequate to compute such observables to leading order in the running coupling g(T) of high-temperature gauge theories [and all orders in 1/log g(T)-1]. As previously proposed in the literature, a leading-order treatment requires including both 2leftrightarrow2 particle scattering processes as well as effective ``1leftrightarrow2'' collinear splitting processes in the Boltzmann equations. The latter account for nearly collinear bremsstrahlung and pair production/annihilation processes which take place in the presence of fluctuations in the background gauge field. Our effective kinetic theory is applicable not only to near-equilibrium systems (relevant for the calculation of transport coefficients), but also to highly non-equilibrium situations, provided some simple conditions on distribution functions are satisfied.

  9. High temperature experimental characterization of microscale thermoelectric effects

    Science.gov (United States)

    Favaloro, Tela

    temperature vacuum thermostats are designed and fabricated with optical imaging capability and interchangeable measurement stages for various electrical and thermoelectric characterizations. We demonstrate the simultaneous measurement of in-plane electrical conductivity and Seebeck coefficient of thin-film or bulk thermoelectric materials. Furthermore, we utilize high-speed circuitry to implement the transient Harman technique and directly determine the cross-plane figure of merit of thin film thermoelectric materials at high temperatures. Transient measurements on thin film devices are subject to complications from the growth substrate, non-ideal contacts and other detrimental thermal and electrical effects. A strategy is presented for optimizing device geometry to mitigate the impact of these parasitics. This design enabled us to determine the cross-plane thermoelectric material properties in a single high temperature measurement of a 25mum InGaAs thin film with embedded ErAs (0.2%) nanoparticles using the bipolar transient Harman technique in conjunction with thermoreflectance thermal imaging. This approach eliminates discrepancies and potential device degradation from the multiple measurements necessary to obtain individual material parameters. Finite element method simulations are used to analyze non-uniform current and temperature distributions over the device area and determine the three dimensional current path for accurate extraction of material properties from the thermal images. Results match with independent measurements of thermoelectric material properties for the same material composition, validating this approach. We apply high magnification thermoreflectance imaging to create temperature maps of vanadium dioxide nanobeams and examine electro-thermal energy conversion along the nanobeam length. The metal to insulator transition of strongly correlated materials is subject to strong lattice coupling which brings about the unique one-dimensional alignment of

  10. Effects of temperature on the structure of neutron stars at high temperature

    Science.gov (United States)

    Zhu, Liang-gui; Lu, Jun-Li; Wang, Li

    2018-01-01

    In Newtonian physics, higher temperature leads to higher thermal pressure, which provides stronger support against the gravitational contraction of stars. However, in the temperature range of tens of MeV involved in the evolution of a proto-neutron star or a higher massive neutron star, the effects of temperature are richer. We showed that, for a high temperature neutron star (HTNS) constructed with a realistic equation of state (EOS), the HTNS may expand or contract during cooling, the central density may increase or decrease, the quasi-normal mode oscillation frequencies may increase or decrease, and in particular, (i) independent of the EOS, for a HTNS of a given mass, there exists a maximum temperature T_{max} that it could ever attend at birth (with the value of T_{max} different for different EOS), and (ii) for the Hempel EOS and the Shen EOS, there is a range of mass that the HTNS may gravitationally collapse after a period of radiative cooling; however, for the Lattimer-Swesty EOS and Banik EOS, no delayed collapse is possible. Our study, which describes the cooling of HTNSs with simple quasi-stationary TOV sequences, provides an understanding of the effects of the thermal energy/pressure at high temperature, and a demonstration that different EOSs can lead to qualitatively different evolution paths.

  11. Highly Effective Thermal Regenerator for Low Temperature Cryocoolers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Future missions to investigate the structure and evolution of the universe require highly efficient, low-temperature cryocoolers for low-noise detector systems. We...

  12. The Effects of High Temperature on Gessoes with Different Admixtures

    Science.gov (United States)

    Budu, Ana-Maria; Sandu, Ion; Cristache, Raluca Anamaria

    2014-11-01

    This paper presents the effects of temperature on gessoes that have different substances added, usually used in painting or restoration to enhance the flexibility of the ground layer or to create a suitable gesso for the specific painting technique. Five samples of gesso were made and applied on Balsa wood (a dry, stable wood that is used in restoration for completing the missing elements of the panel). After the thermal treatment, the samples were analyzed optical, by microscopy and colorimetry. The results showed small differences in colour, but no cracks of the gessoes

  13. Pseudogaps and Impurity Effects in High Temperature Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    White, Paul J.

    2003-02-25

    In science the questions found are almost as important as the answers. High temperature (high T{sub c}) superconductivity is a phenomenon that has made researchers question accepted notions of solids in many aspects. Many ideas need revision such as BCS superconductivity and the quasiparticle notion. Clearly, these are large issues and this body of work seeks only to add some insight into these things. This work contains angle resolved photoemission data from BSCCO (Bi{sub 2} Sr{sub 2} Ca Cu{sub 2} O{sub 8+{delta}}), a high T{sub c} material chosen for convenience with respect to the experimental technique. In particular, the studies included O doped BSCCO, single plane BSCCO, and Zn doped BSCCO. O doping, a common tool for altering the carrier concentration, helped to establish the origin of T{sub c} as being limited by either phase fluctuations or the superconductor pairing strength. While reestablishing the agreement of the data with d-wave pairing, the data also demonstrated the relevant energy scales of interest across the doping regime. In studying single plane BSCCO as a function of carrier concentration, d-wave pairing again was reinforced and the limiting factors of T{sub c} in the single layered compound proved to be quite similar to that of the bilayer compound. The results for Zn doped BSCCO are presented in a more phenomenological flavor. Significant changes occurred in the spectra such as the suppression of the superconducting dip and the spectral peak along {Lambda}Y. While a unique microscopic theory does not readily present itself, these are dramatic changes to key portions of BSCCO spectra. Also, an anomalous change of spectral weight appeared in this material.

  14. The Effect of Acclimation to Sublethal Temperature on Subsequent Susceptibility of Sitophilus zeamais Mostchulsky (Coleoptera: Curculionidae) to High Temperatures.

    Science.gov (United States)

    Lü, Jianhua; Zhang, Huina

    2016-01-01

    Heat treatment is a popular alternative to synthetic pesticides in disinfesting food-processing facilities and empty grain storages. Sitophilus zeamais Mostchulsky is one of the most cosmopolitan and destructive insects found in empty grain storage facilities and processing facilities. The effect of acclimation in S. zeamais adults to sublethal high temperature on their subsequent susceptibility to high temperatures was investigated. S. zeamais adults were acclimated to 36°C for 0 (as a control), 1, 3, and 5 h, and then were exposed at 43, 47, 51, and 55°C for different time intervals respectively. Acclimation to sublethal high temperature significantly reduced subsequent susceptibility of S. zeamais adults to lethal high temperatures of 43, 47, 51, and 55°C, although the mortality of S. zeamais adults significantly increased with increasing exposure time at lethal high temperatures. The mortality of S. zeamais adults with 1, 3, and 5 h of acclimation to 36°C was significantly lower than that of S. zeamais adults without acclimation when exposed to the same lethal high temperatures. The present results suggest that the whole facility should be heated to target lethal high temperature as soon as possible, avoiding decreasing the control effectiveness of heat treatment due to the acclimation in stored product insects to sublethal temperature.

  15. Effects of catalyst height on diamond crystal morphology under high pressure and high temperature

    Science.gov (United States)

    Ya-Dong, Li; Xiao-Peng, Jia; Bing-Min, Yan; Ning, Chen; Chao, Fang; Yong, Li; Hong-An, Ma

    2016-04-01

    The effect of the catalyst height on the morphology of diamond crystal is investigated by means of temperature gradient growth (TGG) under high pressure and high temperature (HPHT) conditions with using a Ni-based catalyst in this article. The experimental results show that the morphology of diamond changes from an octahedral shape to a cub-octahedral shape as the catalyst height rises. Moreover, the finite element method (FEM) is used to simulate the temperature field of the melted catalyst/solvent. The results show that the temperature at the location of the seed diamond continues to decrease with the increase of catalyst height, which is conducive to changing the morphology of diamond. This work provides a new way to change the diamond crystal morphology. Project supported by the National Natural Science Foundation of China (Grant No. 51172089), the Program for New Century Excellent Talents in University, the Natural Science Foundation of Guizhou Provincial Education Department (Grant No. KY[2013]183), and the Collaborative Fund of Science and Technology Office of Guizhou Province, China (Grant No. LH[2015]7232).

  16. High temperature study of flexible silicon-on-insulator fin field-effect transistors

    KAUST Repository

    Diab, Amer El Hajj

    2014-09-29

    We report high temperature electrical transport characteristics of a flexible version of the semiconductor industry\\'s most advanced architecture: fin field-effect transistor on silicon-on-insulator with sub-20 nm fins and high-κ/metal gate stacks. Characterization from room to high temperature (150 °C) was completed to determine temperature dependence of drain current (Ids), gate leakage current (Igs), transconductance (gm), and extracted low-field mobility (μ0). Mobility degradation with temperature is mainly caused by phonon scattering. The other device characteristics show insignificant difference at high temperature which proves the suitability of inorganic flexible electronics with advanced device architecture.

  17. High-temperature superconductors

    CERN Document Server

    Saxena, Ajay Kumar

    2010-01-01

    The present book aims at describing the phenomenon of superconductivity and high-temperature superconductors discovered by Bednorz and Muller in 1986. The book covers the superconductivity phenomenon, structure of high-Tc superconductors, critical currents, synthesis routes for high Tc materials, superconductivity in cuprates, the proximity effect and SQUIDs, theories of superconductivity and applications of superconductors.

  18. High temperature effects on flavones accumulation and antioxidant ...

    African Journals Online (AJOL)

    Scutellaria baicalensis is a traditional Chinese medicinal plant that has long been grown in Hubei Province. However, increasing average annual temperatures in the region have made plants unsuitable for medicinal use. Two flavones, baicalin and baicalein, are the major active ingredients of S. baicalensis.

  19. Investigation of renormalization effects in high temperature cuprate superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Zabolotnyy, Volodymyr B.

    2008-04-16

    It has been found that the self-energy of high-T{sub C} cuprates indeed exhibits a well pronounced structure, which is currently attributed to coupling of the electrons either to lattice vibrations or to collective magnetic excitations in the system. To clarify this issue, the renormalization effects and the electronic structure of two cuprate families Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} and YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} were chosen as the main subject for this thesis. With a simple example of an electronic system coupled to a collective mode unusual renormalization features observed in the photoemission spectra are introduced. It is shown that impurity substitution in general leads to suppression of the unusual renormalization. Finally an alternative possibility to obtain a purely superconducting surface of Y-123 via partial substitution of Y atoms with Ca is introduced. It is shown that renormalization in the superconducting Y-123 has similar strong momentum dependence as in the Bi-2212 family. It is also shown that in analogy to Bi-2212 the renormalization appears to have strong dependence on the doping level (no kinks for the overdoped component) and practically vanishes above T{sub C} suggesting that coupling to magnetic excitations fits much better than competing scenarios, according to which the unusual renormalization in ARPES spectra is caused by the coupling to single or multiple phononic modes. (orig.)

  20. Thermoset recycling via high-pressure high-temperature sintering: Revisiting the effect of interchange chemistry

    Science.gov (United States)

    Morin, Jeremy Edward

    In 1844 Charles Goodyear obtained U.S. Patent #3,633 for his "Gum Elastic Composition". In a published circular, which describes his patent for the sulfur vulcanization of gum elastic composition, he stated: "No degree of heat, without blaze, can melt it (rubber)... It resists the most powerful chemical reagents. Aquafortis (nitric acid), sulphuric acid, essential and common oils, turpentine and other solvents... ..." Goodyear's sulfur vulcanization of rubber fueled much of the industrial revolution and made transportation possible, as it exists today. In doing so, Goodyear created one of the most difficult materials to recycle. Rubber will not melt, dissolve, or lend itself to the usual methods of chemical decomposition. Ironically, Goodyear recognized this problem and in 1853 he patented the process of adding ground rubber to virgin material, now currently known as regrind blending. Today, scrap tires represent one of the most serious sources of pollution in the world. Studies estimate that there are roughly 2 billion scrap tires in U.S. landfills and more are being added at a rate of over 273 million tires per year. Current methods of recycling waste tires are crude, ineffective, and use rubber powder as a low cost filler instead of a new rubber. The groundwork for a very simple and effective method of producing high-quality rubber goods using 100% scrap rubber was discovered in 1944 by A. V. Tobolsky et al. This application, however, was not recognized until recently in our laboratory. The process as studied to date represents a method of creating quality, high-value added rubber goods with nothing other than heat and pressure. High pressure is required to obtain a void-free compaction of the rubber particles by forcing all of the free surfaces into intimate contact. High temperature then activates the chemical rearrangement, scission, and reformation of the chemical bonds thus providing new bridges between the once fractured interfaces. This occurs both within

  1. Hall effect in CNT doped YBCO high temperature superconductor

    Directory of Open Access Journals (Sweden)

    S Dadras

    2010-09-01

    Full Text Available In order to study Hall effect in pure and CNT doped YBCO polycrystalline samples, we have measured longitudinal and transverse voltages at the different magnetic field (0-9T in the vortex state. We found a sign reversal for pure sample near 3T and double sign reversal of the Hall coefficient for CNT doped sample near 3 and 5T. It can be deduced that CNT doping caused strong flux pinning and Hall double sign reversal in this compound.

  2. Radiation and temperature effects on electronic components investigated under the CSTI high capacity power project

    Science.gov (United States)

    Schwarze, Gene E.; Niedra, Janis M.; Frasca, Albert J.; Wieserman, William R.

    1993-01-01

    The effects of nuclear radiation and high temperature environments must be fully known and understood for the electronic components and materials used in both the Power Conditioning and Control subsystem and the reactor Instrumentation and Control subsystem of future high capacity nuclear space power systems. This knowledge is required by the designer of these subsystems in order to develop highly reliable, long-life power systems for future NASA missions. A review and summary of the experimental results obtained for the electronic components and materials investigated under the power management element of the Civilian Space Technology Initiative (CSTI) high capacity power project are presented: (1) neutron, gamma ray, and temperature effects on power semiconductor switches, (2) temperature and frequency effects on soft magnetic materials; and (3) temperature effects on rare earth permanent magnets.

  3. High temperature and drought stress effects on survival of Pinus ponderosa seedlings.

    Science.gov (United States)

    Kolb, P F; Robberecht, R

    1996-08-01

    We studied the effects of high temperature and drought on the survival, growth and water relations of seedlings of Pinus ponderosa (Dougl.) Lawson, one of few coniferous tree species that can successfully colonize drought-prone sites with high soil surface temperatures. Temperature profiles were measured with 0.07-mm thermocouples in a sparse ponderosa pine forest in northern Idaho. The soil surface and the adjacent 5 mm of air reached maximum temperatures exceeding 75 degrees C, well above the lethal temperature threshold for most plants. Air temperatures 50 mm above the soil surface (seedling needle height) rarely exceeded 45 degrees C. Pinus ponderosa seedlings that survived maintained basal stem temperatures as much as 15 degrees C lower than the surrounding air. The apparent threshold temperature at the seedling stem surface resulting in death was approximately 63 degrees C for less than 1 min. No correlation between seedling mortality and needle temperature was found, although some needles reached temperatures as high as 60 degrees C for periods of cooling the stem below the lethal threshold temperature. Heat exchange calculations showed that rapid water flow through seedling stems can absorb sufficient energy to reduce stem temperature by 30 degrees C during peak sunlight hours.

  4. Highly efficient high temperature electrolysis

    DEFF Research Database (Denmark)

    Hauch, Anne; Ebbesen, Sune; Jensen, Søren Højgaard

    2008-01-01

    High temperature electrolysis of water and steam may provide an efficient, cost effective and environmentally friendly production of H-2 Using electricity produced from sustainable, non-fossil energy sources. To achieve cost competitive electrolysis cells that are both high performing i.e. minimum...... electrolysis is favourable from a thermodynamic point of view, because a part of the required energy can be supplied as thermal heat, and the activation barrier is lowered increasing the H-2 production rate. Only two types of cells operating at high temperature (above 200 degrees C) have been described...... electrolysis using SOECs is competitive to H-2 production from fossil fuels at electricity prices below 0.02-0.03 is an element of per kWh. Though promising SOEC results on H-2 production have been reported a substantial R&D is still required to obtain inexpensive, high performing and long-term stable...

  5. High autumn temperature delays spring bud burst in boreal trees, counterbalancing the effect of climatic warming

    Energy Technology Data Exchange (ETDEWEB)

    Heide, O. M. [Agricultural Univesity of Norway, Department of Biology and Nature Conservation, As (Norway)

    2003-09-01

    The effect of temperature during short-day dormancy induction on the duration and stability of bud dormancy was examined in three boreal tree species (2 birches and 1 alder) grown in a controlled environment. The phenology of the latitudinal range of birch populations, and the relationship between spring bud burst and autumn and spring temperatures were also studied. Results showed that during short-day dormancy induction in the autumn high temperatures delayed bud burst in the following spring in both controlled and natural environments. It is suggested that this response to higher autumn temperatures may be a manifestation of a general synergism between high temperature and short-day photoperiodic processes, and may be an adaptive mechanism common to boreal trees. It is further conjectured that this mechanism may be important in counterbalancing the potentially adverse effects of higher winter temperatures on dormancy stability of boreal trees during climate warming. 23 refs., 2 tabs., 4 figs.

  6. Cooling Effect of Water Injection on a High-Temperature Supersonic Jet

    Directory of Open Access Journals (Sweden)

    Jing Li

    2015-11-01

    Full Text Available The high temperature and high pressure supersonic jet is one of the key problems in the design of solid rocket motors. To reduce the jet temperature and noise, cooling water is typically injected into the exhaust plume. Numerical simulations for the gas-liquid multiphase flow field with mixture multiphase model were developed and a series of experiments were carried out. By introducing the energy source terms caused by the vaporization of liquid water into the energy equation, a coupling solution was developed to calculate the multiphase flow field. The temperature data predictions agreed well with the experimental results. When water was injected into the plume, the high temperature core region area was reduced, and the temperature on the head face was much lower than that without water. The relationship between the reduction of temperature on the bottom plate and the momentum ratio is developed, which can be used to predict the cooling effect of water injection in many cases.

  7. High mortality of Zostera marina under high temperature regimes but minor effects of the invasive macroalgae Gracilaria vermiculophylla

    Science.gov (United States)

    Höffle, H.; Thomsen, M. S.; Holmer, M.

    2011-03-01

    The present study tested for density-dependent effects of the invasive drift macroalgae Gracilaria vermiculophylla (Ohmi) Papenfuss on growth and survival of the native eelgrass, Zostera marina L., under different temperature levels. Three weeks laboratory experiments were conducted in Odense, Denmark, combining three algae densities (control, low 1.9 kg WW m -2, high 4.5 kg WW m -2) with typical Danish summer temperatures (18 °C) and elevated temperatures (21 °C and 27 °C). There was a significant effect of temperature on shoot survival with on average 68% mortality in the high temperature treatment but almost no mortality at the two lower temperatures. The higher mortality was probably caused by high sulphide levels in the sediment pore water (0.6 mmol l -1 at 18 °C compared to 3.7 mmol l -1 at 27 °C). Above-ground growth of the surviving shoots was also significantly affected by temperature, with leaf elongation rates being negatively affected, while the leaf plastochrone interval increased. Relative growth rate was significantly higher at 21 °C than at 18 °C or 27 °C, whereas rhizome elongation was significantly lowest at 27 °C. Elemental sulphur content in the plant tissues increased significantly with temperature and was up to 34 times higher (S 0 in rhizomes) at 27 °C compared to the lower temperatures. In contrast to the temperature effects, cover by G. vermiculophylla did not cause significant effects on any seagrass responses. However, there was a (non-significant) negative effect of algal cover at the highest temperature, where the seagrass is already stressed. The latter results suggest that more studies should test for interaction effects between temperature and other anthropogenic stressors given that temperature is predicted to increase in the near future.

  8. Effect of traps and defects on high temperature performance of Ge channel junctionless nanowire transistors

    Directory of Open Access Journals (Sweden)

    Chuanchuan Sun

    2017-07-01

    Full Text Available We investigate the effect of traps and defects on high temperature performance of p-type germanium-on-insulator (GOI based junctionless nanowire transistors (JNTs at temperatures ranging from 300 to 450 K. Temperature dependence of the main electrical parameters, such as drive current (Ion, leakage current (Ioff, threshold voltage (Vt, transconductance (Gm and subthreshold slope (SS are extracted and compared with the reported results of conventional inversion mode (IM MOSFETs and Si based JNTs. The results show that the high interface trap density (Dit and defects can degrade high temperature reliability of GOI based JNTs significantly, in terms of Ioff, Vt variation, Gm-max and SS values. The Ioff is much more dependent on temperature than Ion and mainly affected by trap-assisted-tunneling (TAT current. The Vt variation with temperature is larger than that for IM MOSFETs and SOI based JNTs, which can be mostly attributed to the high Dit. The high Dit can also induce high SS values. The maximum Gm has a weak dependence on temperature and is significantly influenced by neutral defects scattering. Limiting the Dit and neutral defect densities is critical for the reliability of GOI based JNTs working at high temperatures.

  9. Liquid-phase diffusion bonding: Temperature effects and solute redistribution in high temperature lead-free composite solders

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver [Ames Lab. and Iowa State Univ., Ames, IA (United States); Iowa State Univ., Ames, IA (United States); Choquette, Stephanie [Ames Lab. and Iowa State Univ., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)

    2015-05-17

    Liquid-phase diffusion bonding (LPDB) is being studied as the primary phenomena occurring in the development of a high temperature lead-free composite solder paste composed of gas-atomized Cu-10Ni, wt.% (Cu-11Ni, at.%) powder blended with Sn-0.7Cu-0.05Ni-0.01Ge (Sn-1.3Cu-0.1Ni-0.02Ge, at.%) Nihon-Superior SN100C solder powder. Powder compacts were used as a model system. LPDB promotes enhanced interdiffusion of the low-melting alloy matrix with the solid Cu-10Ni reinforcement powder above the matrix liquidus temperature. The initial study involved the effective intermetallic compound (IMC) compositions and microstructures that occur at varying reflow temperatures and times between 250-300°C and 30-60s, respectively. Certain reflow temperatures encourage adequate interdiffusion to form a continuous highly-conductive network throughout the composite solder joints. The diffusion of nickel, in particular, has a disperse pattern that foreshadows the possibility of a highly-conductive low-melting solder that can be successfully utilized at high temperatures.

  10. High mortality of Zostera marina under high temperature regimes but minor effects of the invasive macroalgae Gracilaria vermiculophylla

    DEFF Research Database (Denmark)

    Höffle, Hannes; Thomsen, M.S.; Holmer, M.

    2011-01-01

    , Denmark, combining three algae densities (control, low 1.9 kg WW m2, high 4.5 kg WW m2) with typical Danish summer temperatures (18 C) and elevated temperatures (21 C and 27 C). There was a significant effect of temperature on shoot survival with on average 68% mortality in the high temperature treatment...... but almost no mortality at the two lower temperatures. The higher mortality was probably caused by high sulphide levels in the sediment pore water (0.6 mmol l1 at 18 C compared to 3.7 mmol l1 at 27 C). Above-ground growth of the surviving shoots was also significantly affected by temperature, with leaf...

  11. Z(3)-symmetric effective theory for SU(3) Yang-Mills theory at high temperature

    Science.gov (United States)

    Vuorinen, A.; Yaffe, Laurence G.

    2006-07-01

    A three-dimensional effective theory for high temperature SU(3) gauge theory, which maintains the Z(3) center symmetry of the full theory, is constructed. Such a Z(3) invariant effective theory should be applicable to a wider temperature range than the usual effective theory, known as EQCD, which fails to respect the center symmetry. This center-symmetric effective theory can reproduce domain wall and phase transition properties that are not accessible in EQCD. After identifying a convenient class of Z(3) invariant effective theories, we constrain the coefficients of the various terms in the Lagrangian using leading-order matching to EQCD at high temperature, plus matching of domain wall properties in the full theory. We sketch the expected structure of the phase diagram of the effective theory and briefly discuss the prospects of numerical simulations and the addition of quarks.

  12. Effect of moderate high temperature on the vegetative growth and potassium allocation in olive plants.

    Science.gov (United States)

    Benlloch-González, María; Quintero, José Manuel; Suárez, María Paz; Sánchez-Lucas, Rosa; Fernández-Escobar, Ricardo; Benlloch, Manuel

    2016-12-01

    There is little information about the prolonged effect of a moderately high temperature on the growth of olive (Olea europaea L.). It has been suggested that when the temperature of the air rises above 35°C the shoot growth of olive is inhibited while there is any reference on how growth is affected when the soil is warmed. In order to examine these effects, mist-cuttings and young plants generated from seeds were grown under moderate high temperature (37°C) for 64 and 42days respectively. In our study, plant dry matter accumulation was reduced when the temperature of both the air and the root medium was moderately high. However, when the temperature of the root medium was 25°C, the inhibitory effect of air high temperature on plant growth was not observed. The exposure of both the aerial part and the root to moderate high temperature also reduced the accumulation of K(+) in the stem and the root, the water use efficiency and leaf relative water content. However, when only the aerial part was exposed to moderate high temperature, the accumulation of K(+) in the stem, the water use efficiency and leaf relative water content were not modified. The results from this study suggest that the olive is very efficient in regulating the water and potassium transport through the plant when only the atmosphere surrounding the aerial part is warmed up. However, an increase in the soil temperature decrease root K(+) uptake and its transport to the aerial parts resulting in a reduction in shoot water status and growth. Copyright © 2016 Elsevier GmbH. All rights reserved.

  13. Combined Non-Target Effects of Insecticide and High Temperature on the Parasitoid Bracon nigricans.

    Directory of Open Access Journals (Sweden)

    Khaled Abbes

    Full Text Available We studied the acute toxicity and the sublethal effects, on reproduction and host-killing activity, of four widely used insecticides on the generalist parasitoid Bracon nigricans (Hymenoptera: Braconidae, a natural enemy of the invasive tomato pest, Tuta absoluta (Lepidoptera: Gelechiidae. Laboratory bioassays were conducted applying maximum insecticide label rates at three constant temperatures, 25, 35 and 40°C, considered as regular, high and very high, respectively. Data on female survival and offspring production were used to calculate population growth indexes as a measure of population recovery after pesticide exposure. Spinetoram caused 80% mortality at 25°C and 100% at higher temperatures, while spinosad caused 100% mortality under all temperature regimes. Cyantraniliprole was slightly toxic to B. nigricans adults in terms of acute toxicity at the three temperatures, while it did not cause any sublethal effects in egg-laying and host-killing activities. The interaction between the two tested factors (insecticide and temperature significantly influenced the number of eggs laid by the parasitoid, which was the lowest in the case of females exposed to chlorantraniliprole at 35°C. Furthermore, significantly lower B. nigricans demographic growth indexes were estimated for all the insecticides under all temperature conditions, with the exception of chlorantraniliprole at 25°C. Our findings highlight an interaction between high temperatures and insecticide exposure, which suggests a need for including natural stressors, such as temperature, in pesticide risk assessments procedures.

  14. Combined Non-Target Effects of Insecticide and High Temperature on the Parasitoid Bracon nigricans

    Science.gov (United States)

    Abbes, Khaled; Biondi, Antonio; Kurtulus, Alican; Ricupero, Michele; Russo, Agatino; Siscaro, Gaetano; Chermiti, Brahim; Zappalà, Lucia

    2015-01-01

    We studied the acute toxicity and the sublethal effects, on reproduction and host-killing activity, of four widely used insecticides on the generalist parasitoid Bracon nigricans (Hymenoptera: Braconidae), a natural enemy of the invasive tomato pest, Tuta absoluta (Lepidoptera: Gelechiidae). Laboratory bioassays were conducted applying maximum insecticide label rates at three constant temperatures, 25, 35 and 40°C, considered as regular, high and very high, respectively. Data on female survival and offspring production were used to calculate population growth indexes as a measure of population recovery after pesticide exposure. Spinetoram caused 80% mortality at 25°C and 100% at higher temperatures, while spinosad caused 100% mortality under all temperature regimes. Cyantraniliprole was slightly toxic to B. nigricans adults in terms of acute toxicity at the three temperatures, while it did not cause any sublethal effects in egg-laying and host-killing activities. The interaction between the two tested factors (insecticide and temperature) significantly influenced the number of eggs laid by the parasitoid, which was the lowest in the case of females exposed to chlorantraniliprole at 35°C. Furthermore, significantly lower B. nigricans demographic growth indexes were estimated for all the insecticides under all temperature conditions, with the exception of chlorantraniliprole at 25°C. Our findings highlight an interaction between high temperatures and insecticide exposure, which suggests a need for including natural stressors, such as temperature, in pesticide risk assessments procedures. PMID:26382245

  15. Effects of bonding temperature on microstructure, fracture behavior and joint strength of Ag nanoporous bonding for high temperature die attach

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min-Su, E-mail: mskim927@gmail.com [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Nishikawa, Hiroshi [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2015-10-01

    Ag nanoparticle sintering has received much attention as an alternative joining method to lead-based soldering for high temperature electronic applications. However, there are still certain issues with this method, such as difficulties of in controlling the joining layer thickness and the occurrence of unexpected voids resulting from solvent evaporation. In this study, the effect of bonding temperature (200–400 °C) and environment (air and N{sub 2}) on the joint strength of Ag nanoporous bonding (NPB) on electroless nickel/immersion gold finished Cu disks was investigated. A nanoporous Ag sheet fabricated using dealloying method from an Al–Ag precursor was adopted as the insert material. The NPB was conducted at various temperatures (200–400 °C) for 30 min at a pressure of 20 MPa in both air and N{sub 2} environments. The joint strength of NPB was closely related with the microstructure of the Ag layer and the fracture mode of the joint, and increased with increasing bonding temperature through the formation of strong interface and a coarsened Ag layer. The effect of the bonding environment was not significant, except in the case of bonding temperature of 400 °C.

  16. Effects of High Energy Electron Irradiation on a Yttrium Barium(2) Copper(3) Oxygen(7-delta) High Temperature Superconductor

    Science.gov (United States)

    1991-09-01

    expulsion of magnetic fields from the interior of a superconductor such that B = 0 and is the phenome- non that explains magnetic levitation . From Ohm’s Law...2Cu 30 7 - HIGH TEMPERATURE SUPERCONDUCTOR by Sean Mark Connors September 1991 Thesis Advisor: X. K. Maruyama Approved for public release...if necessary and identify by btock numbe,) FiE GP<P ,€ 5 pCOO HIGH TEMPERATURE SUPERCONDUCTORS , IRRADIATION EFFECTS, ELECTRON IRRADIATION

  17. [Effect of high-temperature phase change material on the performance of infrared decoy].

    Science.gov (United States)

    Wu, Ting-Ting; Chen, Xin; Han, Ai-Jun; Ye, Ming-Quan; Zhao, Min-Chun

    2013-10-01

    The impact of the high-temperature phase change material on conventional infrared decoy's combustion performance and infrared radiation characteristics was studied. The selected high-temperature phase change materials did not reduce infrared radiation in the 3-5 microm or 8-14 microm band of infrared decoy, while extended the burning time, and reduced the burning rate of the grain, thus prolonged the effective interference time of IR decoy. The results show the phase change material is effective infrared decoy functional additives.

  18. High temperature future

    Energy Technology Data Exchange (ETDEWEB)

    Sheinkopf, K. [Solar Energy Research and Education Foundation, Washington, DC (United States)

    1994-09-01

    During the past few years, there have been dramatic accomplishments and success of high temperature solar thermal systems and significant development of these systems. High temperature technologies, about 500 F and higher, such as dish engines, troughs, central receiver power towers and solar process heat systems, have been tested, demonstrated and used in an array of applications, including many cost-effective utility bulk power production and demand side supply projects in the United States. Large systems provide power and hot water to prisons, schools, nursing homes and other institutions. Joint ventures with industry, utility projects, laboratory design assistance and other activities are building a solid industry of US solar thermal systems ready for use today.

  19. Analysis of Environmental Effects on Leaf Temperature under Sunlight, High Pressure Sodium and Light Emitting Diodes.

    Science.gov (United States)

    Nelson, Jacob A; Bugbee, Bruce

    2015-01-01

    The use of LED technology is commonly assumed to result in significantly cooler leaf temperatures than high pressure sodium technology. To evaluate the magnitude of this effect, we measured radiation incident to and absorbed by a leaf under four radiation sources: clear sky sunlight in the field, sunlight in a glass greenhouse, and indoor plants under either high pressure sodium or light emitting diodes. We then applied a common mechanistic energy-balance model to compare leaf to air temperature difference among the radiation sources and environments. At equal photosynthetic photon flux, our results indicate that the effect of plant water status and leaf evaporative cooling is much larger than the effect of radiation source. If plants are not water stressed, leaves in all four radiation sources were typically within 2°C of air temperature. Under clear sky conditions, cool sky temperatures mean that leaves in the field are always cooler than greenhouse or indoor plants-when photosynthetic photon flux, stomatal conductance, wind speed, vapor pressure deficit, and leaf size are equivalent. As water stress increases and cooling via transpiration decreases, leaf temperatures can increase well above air temperature. In a near-worst case scenario of water stress and low wind, our model indicates that leaves would increase 6°, 8°, 10°, and 12°C above air temperature under field, LED, greenhouse, and HPS scenarios, respectively. Because LED fixtures emit much of their heat through convection rather than radiative cooling, they result in slightly cooler leaf temperatures than leaves in greenhouses and under HPS fixtures, but the effect of LED technology on leaf temperature is smaller than is often assumed. Quantifying the thermodynamic outputs of these lamps, and their physiological consequences, will allow both researchers and the horticulture industry to make informed decisions when employing these technologies.

  20. Analysis of Environmental Effects on Leaf Temperature under Sunlight, High Pressure Sodium and Light Emitting Diodes.

    Directory of Open Access Journals (Sweden)

    Jacob A Nelson

    Full Text Available The use of LED technology is commonly assumed to result in significantly cooler leaf temperatures than high pressure sodium technology. To evaluate the magnitude of this effect, we measured radiation incident to and absorbed by a leaf under four radiation sources: clear sky sunlight in the field, sunlight in a glass greenhouse, and indoor plants under either high pressure sodium or light emitting diodes. We then applied a common mechanistic energy-balance model to compare leaf to air temperature difference among the radiation sources and environments. At equal photosynthetic photon flux, our results indicate that the effect of plant water status and leaf evaporative cooling is much larger than the effect of radiation source. If plants are not water stressed, leaves in all four radiation sources were typically within 2°C of air temperature. Under clear sky conditions, cool sky temperatures mean that leaves in the field are always cooler than greenhouse or indoor plants-when photosynthetic photon flux, stomatal conductance, wind speed, vapor pressure deficit, and leaf size are equivalent. As water stress increases and cooling via transpiration decreases, leaf temperatures can increase well above air temperature. In a near-worst case scenario of water stress and low wind, our model indicates that leaves would increase 6°, 8°, 10°, and 12°C above air temperature under field, LED, greenhouse, and HPS scenarios, respectively. Because LED fixtures emit much of their heat through convection rather than radiative cooling, they result in slightly cooler leaf temperatures than leaves in greenhouses and under HPS fixtures, but the effect of LED technology on leaf temperature is smaller than is often assumed. Quantifying the thermodynamic outputs of these lamps, and their physiological consequences, will allow both researchers and the horticulture industry to make informed decisions when employing these technologies.

  1. Effects of Lower Drying-Storage Temperature on the Ductility of High-Burnup PWR Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Billone, M. C. [Argonne National Lab. (ANL), Argonne, IL (United States); Burtseva, T. A. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-08-30

    The purpose of this research effort is to determine the effects of canister and/or cask drying and storage on radial hydride precipitation in, and potential embrittlement of, high-burnup (HBU) pressurized water reactor (PWR) cladding alloys during cooling for a range of peak drying-storage temperatures (PCT) and hoop stresses. Extensive precipitation of radial hydrides could lower the failure hoop stresses and strains, relative to limits established for as-irradiated cladding from discharged fuel rods stored in pools, at temperatures below the ductile-to-brittle transition temperature (DBTT).

  2. Fuel properties effect on the performance of a small high temperature rise combustor

    Science.gov (United States)

    Acosta, Waldo A.; Beckel, Stephen A.

    1989-01-01

    The performance of an advanced small high temperature rise combustor was experimentally determined at NASA-Lewis. The combustor was designed to meet the requirements of advanced high temperature, high pressure ratio turboshaft engines. The combustor featured an advanced fuel injector and an advanced segmented liner design. The full size combustor was evaluated at power conditions ranging from idle to maximum power. The effect of broad fuel properties was studied by evaluating the combustor with three different fuels. The fuels used were JP-5, a blend of Diesel Fuel Marine/Home Heating Oil, and a blend of Suntec C/Home Heating Oil. The fuel properties effect on the performance of the combustion in terms of pattern factor, liner temperatures, and exhaust emissions are documented.

  3. Effects of cryomilling on the microstructures and high temperature mechanical properties of oxide dispersion strengthened steel

    Science.gov (United States)

    Gwon, Jin-Han; Kim, Jeoung-Han; Lee, Kee-Ahn

    2015-04-01

    The effects of cryomilling on the microstructures and high temperature mechanical properties of oxide dispersion-strengthened (ODS) steel were examined. Cryomilling was newly tried on this ODS steel to control oxides, grains, and dislocation microstructures. Fe-14Cr-3W-0.4Ti (wt.%) alloy powder and 0.3 wt.%Y2O3 powder were mixed and were mechanically alloyed (MA) through ball milling at each of room temperature (RT) and -150 °C and then hot isostatic pressing (HIP), hot rolling, and annealing processes were implemented to manufacture two types of ODS ferritic steel, K1 (RT) and K4 (-150 °C). Oxide particles were shown to be finer and more uniformly distributed in K4 (5-10 nm size distribution) than in K1 (average size 30 nm). The two alloys were subjected to high temperature compression (RT ∼ 900 °C) tests. K4 represented higher yield strength under all temperature conditions. However, K4 showed rapid strength decreases at high temperatures exceeding 700 °C and showed similar levels of strengths to K1 at 900 °C. This is considered attributable to the fact that although cryomilling increased the number density of oxide particles, it simultaneously reduced grain sizes too much, so that grain boundary weakening at high temperatures could not be sufficiently prevented.

  4. Effects of cryomilling on the microstructures and high temperature mechanical properties of oxide dispersion strengthened steel

    Energy Technology Data Exchange (ETDEWEB)

    Gwon, Jin-Han [Dept. of Advanced Mat. Eng., Andong National University, Andong 760-749 (Korea, Republic of); Kim, Jeoung-Han [Dept. of Advanced Mat. Eng., Hanbat National University, Daejeon 305-719 (Korea, Republic of); Lee, Kee-Ahn, E-mail: keeahn@andong.ac.kr [Dept. of Advanced Mat. Eng., Andong National University, Andong 760-749 (Korea, Republic of)

    2015-04-15

    The effects of cryomilling on the microstructures and high temperature mechanical properties of oxide dispersion-strengthened (ODS) steel were examined. Cryomilling was newly tried on this ODS steel to control oxides, grains, and dislocation microstructures. Fe–14Cr–3W–0.4Ti (wt.%) alloy powder and 0.3 wt.%Y{sub 2}O{sub 3} powder were mixed and were mechanically alloyed (MA) through ball milling at each of room temperature (RT) and −150 °C and then hot isostatic pressing (HIP), hot rolling, and annealing processes were implemented to manufacture two types of ODS ferritic steel, K1 (RT) and K4 (−150 °C). Oxide particles were shown to be finer and more uniformly distributed in K4 (5–10 nm size distribution) than in K1 (average size 30 nm). The two alloys were subjected to high temperature compression (RT ∼ 900 °C) tests. K4 represented higher yield strength under all temperature conditions. However, K4 showed rapid strength decreases at high temperatures exceeding 700 °C and showed similar levels of strengths to K1 at 900 °C. This is considered attributable to the fact that although cryomilling increased the number density of oxide particles, it simultaneously reduced grain sizes too much, so that grain boundary weakening at high temperatures could not be sufficiently prevented.

  5. High temperature measuring device

    Science.gov (United States)

    Tokarz, Richard D.

    1983-01-01

    A temperature measuring device for very high design temperatures (to 2,000.degree. C.). The device comprises a homogenous base structure preferably in the form of a sphere or cylinder. The base structure contains a large number of individual walled cells. The base structure has a decreasing coefficient of elasticity within the temperature range being monitored. A predetermined quantity of inert gas is confined within each cell. The cells are dimensionally stable at the normal working temperature of the device. Increases in gaseous pressure within the cells will permanently deform the cell walls at temperatures within the high temperature range to be measured. Such deformation can be correlated to temperature by calibrating similarly constructed devices under known time and temperature conditions.

  6. Effect of high-temperature heat treatment duration on the purity and ...

    Indian Academy of Sciences (India)

    The effect of high-temperature heat treatment on purity and structural changes of multiwalled carbon nanotubes (MWCNTs) were studied by subjecting the raw MWCNTs (pristine MWCNTs) to 2600°C for 60 and 120 min. Thermogravimetric analysis (TGA), X-ray diffraction, Raman spectroscopy, transmission electron ...

  7. Effect of high ambient temperature on behavior of sheep under semi-arid tropical environment

    Science.gov (United States)

    De, Kalyan; Kumar, Davendra; Saxena, Vijay Kumar; Thirumurugan, Palanisamy; Naqvi, Syed Mohammed Khursheed

    2017-07-01

    High environmental temperature is a major constraint in sheep production under semi-arid tropical environment. Behavior is the earliest indicator of animal's adaptation and responses to the environmental alteration. Therefore, the objective of this study was to assess the effects of high ambient temperature on the behavior of sheep under a semi-arid tropical environment. The experiment was conducted for 6 weeks on 16 Malpura cross (Garole × Malpura × Malpura (GMM)) rams. The rams were divided equally into two groups, designated as C and T. The rams of C were kept in comfortable environmental conditions served as control. The rams of T were exposed to a different temperature at different hours of the day in a climatic chamber, to simulate a high environmental temperature of summer in semi-arid tropic. The behavioral observations were taken by direct instantaneous observation at 15-min intervals for each animal individually. The feeding, ruminating, standing, and lying behaviors were recorded twice a week from morning (0800 hours) to afternoon (1700 hours) for 6 weeks. Exposure of rams to high temperature (T) significantly ( P animals of T spent significantly ( P behavior of sheep which is directed to circumvent the effect of the stressor.

  8. High-Temperature Compensation Effect of Dynamic Viscosity in Multicomponent Hydrocarbon Media

    Science.gov (United States)

    Dolomatov, M. Yu.; Nizamova, G. I.; Zhuravleva, N. A.

    2017-07-01

    Linear dependences connecting the preexponent to the activation energy of viscous flow in the Frenkel-Eyring equation have been obtained for multicomponent hydrocarbon media (high-boiling distillate fractions). For these media, the kinetic compensation effect has been established whose distinctive feature is its action in the temperature range including the temperature of thermal destruction (400-450°C) of the indicated media. The obtained results have been confirmed by statistical-processing data and make it possible to predict the dynamic viscosity of multicomponent hydrocarbon systems, such as tars and other high-boiling oil distillates.

  9. Effects of High Temperature on the Microstructure of Automotive Engine Valves

    Directory of Open Access Journals (Sweden)

    Ajay Pandey

    2014-03-01

    Full Text Available In this paper, failures of automobile valves are considered and discussed. The changes in microstructures of valves were studied and analyzed with the aid of a Scanning Electron Microscope (SEM. Specimens were prepared out of failed engine valves whereas new valves were also analyzed for the sake of comparison. This was done by image analysis of specimens of failed and new valves at adequate magnification. The benchmarking of microstructures of failed valves v/s new valves revealed that the size of grains, grain boundaries, and distribution of carbide particles across the material matrix is affected by high temperature conditions and the effects are more severe for exhaust valves. The microstructure of valve material shows discernible changes after operating at high temperatures. The grain size of the material also changes at high temperature, thus resulting in a reduction in the hardness of the valve material which, in turn, causes more wear.

  10. Temperature and high pressure effects on the structural features of catalytic nanocomposites oxides by Raman spectroscopy

    Science.gov (United States)

    da Silva, Antonio N.; Pinto, Raffael C. F.; Freire, Paulo T. C.; Junior, Jose Alves L.; Oliveira, Alcineia C.; Filho, Josué M.

    2015-03-01

    Structural characterizations of nanostructured oxides were studied by X-ray diffraction (XRD), Raman and infrared spectroscopy. The oxides catalysts namely, SnO2, ZrO2, CeO2, MnOx, Al2O3 and TiO2 were prepared by a nanocasting route and the effect of the temperature and pressure on the stability of the solids was evaluated. Raman spectra showed that ZrO2 and TiO2 exhibited phase transitions at moderate temperatures whereas CeO2, SnO2 and MnOx had an effective creation of defects in their structures upon annealing at elevated temperatures. The results suggested also that the effect of the temperature on the particles growth is related to the type of oxide. In this regard, phase transition by up to 600 °C accelerated the sintering of ZrO2 and CeO2 grains compared to TiO2, SnO2 and MnOx counterparts. Under hydrostatic pressures lower than 10 GPa, rutile TiO2 and tetragonal ZrO2 exhibited pressure induced phase transition whereas CeO2 and SnO2 were stable at pressures close to 15 GPa. The experiments revealed that the nanostructured SnO2 oxide exhibited stable performance at relatively high temperatures without phase transition or sintering, being suitable to be used as catalysts in the range of temperature and pressure studied.

  11. Effect of Temperature on Chinese Rice Wine Brewing with High Concentration Presteamed Whole Sticky Rice

    Science.gov (United States)

    Zhang, Hong-Tao; Xiong, Weili; Hu, Jianhua; Xu, Baoguo; Lin, Chi-Chung; Xu, Ling; Jiang, Lihua

    2014-01-01

    Production of high quality Chinese rice wine largely depends on fermentation temperature. However, there is no report on the ethanol, sugars, and acids kinetics in the fermentation mash of Chinese rice wine treated at various temperatures. The effects of fermentation temperatures on Chinese rice wine quality were investigated. The compositions and concentrations of ethanol, sugars, glycerol, and organic acids in the mash of Chinese rice wine samples were determined by HPLC method. The highest ethanol concentration and the highest glycerol concentration both were attained at the fermentation mash treated at 23°C. The highest peak value of maltose (90 g/L) was obtained at 18°C. Lactic acid and acetic acid both achieved maximum values at 33°C. The experimental results indicated that temperature contributed significantly to the ethanol production, acid flavor contents, and sugar contents in the fermentation broth of the Chinese rice wines. PMID:24672788

  12. RETRACTED ARTICLE: Effect of magnetic relaxation on flux jump in high temperature superconductors

    Science.gov (United States)

    Zhao, Y.-F.; He, T.-H.

    2010-10-01

    The effect of magnetic relaxation on flux jump is studied in high temperature superconducting slab. The magnetothermal diffusion equations based on the Kim model are presented in this paper to estimate the effect of magnetic relaxation on flux jump inside the slab in the flux dynamics process. Numerical results obtained show that the flux-jump phenomenon could be suppressed by the magnetic relaxation and the dependence of the number of flux jumps on the relaxation time are obvious.

  13. Effect of high ambient temperature on behavior of sheep under semi-arid tropical environment.

    Science.gov (United States)

    De, Kalyan; Kumar, Davendra; Saxena, Vijay Kumar; Thirumurugan, Palanisamy; Naqvi, Syed Mohammed Khursheed

    2017-07-01

    High environmental temperature is a major constraint in sheep production under semi-arid tropical environment. Behavior is the earliest indicator of animal's adaptation and responses to the environmental alteration. Therefore, the objective of this study was to assess the effects of high ambient temperature on the behavior of sheep under a semi-arid tropical environment. The experiment was conducted for 6 weeks on 16 Malpura cross (Garole × Malpura × Malpura (GMM)) rams. The rams were divided equally into two groups, designated as C and T. The rams of C were kept in comfortable environmental conditions served as control. The rams of T were exposed to a different temperature at different hours of the day in a climatic chamber, to simulate a high environmental temperature of summer in semi-arid tropic. The behavioral observations were taken by direct instantaneous observation at 15-min intervals for each animal individually. The feeding, ruminating, standing, and lying behaviors were recorded twice a week from morning (0800 hours) to afternoon (1700 hours) for 6 weeks. Exposure of rams to high temperature (T) significantly (P < 0.05) decreased the proportion of time spent in feeding during the observation period in most of the hours of the day as compared to the C. The proportion of time spent in rumination and lying was significantly (P < 0.05) lower in the T group compared to the C. The animals of T spent significantly (P < 0.05) more time in rumination in standing position as compared to the C. The overall proportion of time spent in standing, panting in each hour, and total panting time was significantly (P < 0.05) higher in the T as compared to the C. The result of the study indicates that the exposure of sheep to high ambient temperature severely modulates the behavior of sheep which is directed to circumvent the effect of the stressor.

  14. Effect of Microstructure on the High Temperature Fatigue Properties of Two Ni-based Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Muralidharan, Govindarajan [ORNL; Battiste, Rick [ORNL; Kenik, Edward A [ORNL; Bentley, James [ORNL; Bunting, Bruce G [ORNL

    2010-01-01

    There is significant need for Ni-based superalloys in the next generation automotive engine components such as exhaust valves. High temperature, high cycle fatigue life is one of the important properties required for such applications. The focus of this work is to evaluate the effect of microstructure on the high cycle fatigue properties of two Ni-based alloys, alloy 751, an alloy used in these applications at lower temperatures, and Waspaloy. High cycle fatigue lives of the alloys at 870oC were evaluated using in-situ high temperature fully reversed fatigue tests at 870oC and a nominal frequency of 30 Hz. Scanning electron microscopy and transmission electron microscopy were used to characterize the microstructure of the alloys. Computational modeling was used to calculate the equilibrium microstructure and microstructural coarsening at 870oC. Correlation of fatigue properties with microstructure of the alloys shows that for the experimental conditions used in the study, the fatigue life of Waspaloy, which has greater high temperature strength and larger volume fraction, is better than that of alloy 751.

  15. High Speed Submarine Optical Fiber Communication System:Pressure and Temperature Effects

    Directory of Open Access Journals (Sweden)

    A. A. Mohammed

    2012-07-01

    Full Text Available In the present paper, the performance of high speed submarine optical fiber cable systems is investigated, taking into account both the pressure and the temperature effects. Both the pressure and the temperature are depth-dependent variables, while both the spectral losses and the dispersion effects are temperature as well as wavelength dependent variables. Two important cases with real fibers are processed: a case with dispersion cancellation and a case without dispersion cancellation. It is found that the ocean pressure (due to the depth shifts the dispersion-free wavelength towards the third communication window. In general, as the depth increases the maximum transmitted bit rate increases in the range of interest. The system capacity as well as the spectral losses, and the dispersion effects are parametrically investigated over wide-range ranges of the set of affecting parameters {wavelength, ocean depth (and consequently the ocean pressure and temperature, and the chemical structure}. Key Words: Submarine Optical Fiber, Undersea Optical Communication, Pressure and Temperature Effects, Transoceanic Optical Communications

  16. Effects of high and low environmental temperatures on clinical course of fowl cholera in turkeys

    Energy Technology Data Exchange (ETDEWEB)

    Simensen, E.; Olson, L.D.; Hahn, G.L.

    1980-01-01

    Turkeys inoculated with Pasteurella multocida either in the palatine air spaces or via drinking water were maintained t high (33.4-37.4 C), low (2.6-5.3 C), and moderate (19.8-22.4 C) temperatures in temperature-controlled chambers to determine the influence environmental temperature had on the pathogenesis of fowl cholera. In inoculated turkeys maintained at high temperatures, there was a delay in the onset of depression and, in most instances, in mortality in relation to those at low or moderate temperatures. In turkeys inoculated via drinking water and maintained at low temperatures, there was a higher mortality than in those at high or moderate temperatures. In turkeys maintained at low temperatures during the preinoculation period, the onset of depression was accelerated more after inoculation than in those maintained at moderate temperatures before inoculation. The percentage of leukocytes in the hematocrit was higher in turkeys inoculated int he palatine air spaces and maintained at low temperatures than in turkeys similarly inoculated but maintained at high or moderate temperatures. Cloacal temperatures were higher in all inoculated turkeys maintained at high temperatures than in those at low or moderate temperatures, and decreased markedly when turkeys became moribund. In turkeys inoculated in the palatine air spaces, deaths from pneumonia occurred more frequently at low temperatures and torticollis occurred more frequently at high temperatures than at the other temperatures.

  17. Effect of tempering temperature on microstructure and mechanical properties of high boron white cast iron

    Directory of Open Access Journals (Sweden)

    Liu Zhongli

    2012-11-01

    Full Text Available The effect of different tempering temperatures on the microstructure and mechanical properties of air-quenched high boron white cast iron was studied. The results indicate that the high boron white cast iron comprises dendritic matrix and inter-dendritic M2B boride; and the matrix comprises martensite and pearlite. After quenching in the air, the matrix is changed into lath martensite; but only 1-μm-size second phase exists in the matrix. After tempering, another second phase of several tens of nanometers is found in the matrix, and the size and quantity increase with an increase in tempering temperature. The two kinds of second precipitation phase with different sizes in the matrix have the same chemical formula, but their forming stages are different. The precipitation phase with larger size forms during the austenitizing process, while the precipitation phase with smaller size forms during the tempering process. When tempered at different temperatures after quenching, the hardness decreases with an increase in the tempering temperature, but it increases a little at 450 ℃ due to the precipitation strengthening effect of the second phase, and it decreases greatly due to the martensite decomposition above 450 ℃. The impact toughness increases a little when tempered below 300 ℃, but it then decreases continuously owing to the increase in size and quantity of the secondary precipitate above 300 ℃. Considered comprehensively, the optimum tempering temperature is suggested at 300 ℃ to obtain a good combination of hardness and toughness.

  18. Effects of sample size on estimation of rainfall extremes at high temperatures

    Directory of Open Access Journals (Sweden)

    B. Boessenkool

    2017-09-01

    Full Text Available High precipitation quantiles tend to rise with temperature, following the so-called Clausius–Clapeyron (CC scaling. It is often reported that the CC-scaling relation breaks down and even reverts for very high temperatures. In our study, we investigate this reversal using observational climate data from 142 stations across Germany. One of the suggested meteorological explanations for the breakdown is limited moisture supply. Here we argue that, instead, it could simply originate from undersampling. As rainfall frequency generally decreases with higher temperatures, rainfall intensities as dictated by CC scaling are less likely to be recorded than for moderate temperatures. Empirical quantiles are conventionally estimated from order statistics via various forms of plotting position formulas. They have in common that their largest representable return period is given by the sample size. In small samples, high quantiles are underestimated accordingly. The small-sample effect is weaker, or disappears completely, when using parametric quantile estimates from a generalized Pareto distribution (GPD fitted with L moments. For those, we obtain quantiles of rainfall intensities that continue to rise with temperature.

  19. Effects of sample size on estimation of rainfall extremes at high temperatures

    Science.gov (United States)

    Boessenkool, Berry; Bürger, Gerd; Heistermann, Maik

    2017-09-01

    High precipitation quantiles tend to rise with temperature, following the so-called Clausius-Clapeyron (CC) scaling. It is often reported that the CC-scaling relation breaks down and even reverts for very high temperatures. In our study, we investigate this reversal using observational climate data from 142 stations across Germany. One of the suggested meteorological explanations for the breakdown is limited moisture supply. Here we argue that, instead, it could simply originate from undersampling. As rainfall frequency generally decreases with higher temperatures, rainfall intensities as dictated by CC scaling are less likely to be recorded than for moderate temperatures. Empirical quantiles are conventionally estimated from order statistics via various forms of plotting position formulas. They have in common that their largest representable return period is given by the sample size. In small samples, high quantiles are underestimated accordingly. The small-sample effect is weaker, or disappears completely, when using parametric quantile estimates from a generalized Pareto distribution (GPD) fitted with L moments. For those, we obtain quantiles of rainfall intensities that continue to rise with temperature.

  20. Effect of Thermal Degradation on High Temperature Ultrasonic Transducer Performance in Small Modular Reactors

    Science.gov (United States)

    Bilgunde, Prathamesh N.; Bond, Leonard J.

    Prototype ultrasonic NDT transducers for use in immersion in coolants for small modular reactors have shown low signal to noise ratio. The reasons for the limitations in performance at high temperature are under investigation, and include changes in component properties. This current work seeks to quantify the issue of thermal expansion and degradation of the piezoelectric material in a transducer using a finite element method. The computational model represents an experimental set up for an ultrasonic transducer in a pulse-echo mode immersed in a liquid sodium coolant. Effect on transmitted and received ultrasonic signal due to elevated temperature (∼200oC) has been analysed.

  1. Cure Cycle Effect on High-Temperature Polymer Composite Structures Molded by VARTM

    Directory of Open Access Journals (Sweden)

    Ahmed Khattab

    2013-01-01

    Full Text Available This paper presents an analytical and experimental investigation of cure cycle effect on carbon-fiber reinforced high-temperature polymer composite structures molded by vacuum assisted resin transfer molding (VARTM. The molded composite structure consists of AS4-8 harness carbon-fiber fabrics and a high-temperature polymer (Cycom 5250-4-RTM. Thermal and resin cure analysis is performed to model the cure cycle of the VARTM process. The temperature and cure variations with time are determined by solving the three-dimensional transient energy and species equations within the composite part. Several case studies were investigated by the developed analytical model. The same cases were also experimentally investigated to determine the ultimate tensile strength for each case. This study helps in developing a science based technology for the VARTM process for the understanding of the process behavior and the effect of the cure cycle on the properties of the molded high-temperature polymer composites.

  2. Effect of High Temperature on the Tensile Behavior of CFRP and Cementitious Composites

    Science.gov (United States)

    Toutanji, Houssam A.

    1999-01-01

    Concrete and other composite manufacturing processes are continuing to evolve and become more and more suited for use in non-Earth settings such as the Moon and Mars. The fact that structures built in lunar environments would experience a range of effects from temperature extremes to bombardment by micrometeorites and that all the materials for concrete production exist on the Moon means that concrete appears to be the most feasible building material. it can provide adequate shelter from the harshness of the lunar environment and at the same time be a cost effective building material. With a return to the Moon planned by NASA to occur after the turn of the century, it will be necessary to include concrete manufacturing as one of the experiments to be conducted in one of the coming missions. Concrete's many possible uses and possibilities for manufacturing make it ideal for lunar construction. The objectives of this research are summarized as follows: i) study the possibility of concrete production on the Moon or other planets, ii) study the effect of high temperature on the tensile behavior of concrete, and iii) study the effect of high temperature on the tensile behavior of carbon fiber reinforced with inorganic polymer composites. Literature review indicates that production of concrete on the Moon or other planets is feasible using the indigenous materials. Results of this study has shown that both the tensile strength and static elastic modulus of concrete decreased with a rise in temperature from 200 to 500 C. The addition of silica fume to concrete showed higher resistance to high temperatures. Carbon fiber reinforced inorganic polymer (CFRIP) composites seemed to perform well up to 300 C. However, a significant reduction in strength was observed of about 40% at 400 C and up to 80% when the specimens were exposed to 700 C.

  3. High-Temperature-Superconducting Weak Link Defined by the Ferroelectric Field Effect

    Science.gov (United States)

    Bégon-Lours, L.; Rouco, V.; Sander, A.; Trastoy, J.; Bernard, R.; Jacquet, E.; Bouzehouane, K.; Fusil, S.; Garcia, V.; Barthélémy, A.; Bibes, M.; Santamaría, J.; Villegas, J. E.

    2017-06-01

    In all-oxide ferroelectric (F E ) superconductors (S ), due to the low carrier concentration of oxides compared to transition metals, the F E interfacial polarization charges induce an accumulation (or depletion) of charge carriers in the S . This effect leads either to an enhancement or a depression of its critical temperature, depending on the F E polarization direction. Here, we exploit this effect at a local scale to define planar weak links in high-temperature-superconducting wires. These experiments are realized in BiFeO3 (F E ) /YBa2Cu3O7 -x (S ) bilayers in which the remnant F E domain structure is "written" by locally applying voltage pulses with a conductive-tip atomic force microscope. In this fashion, the F E domain pattern defines a spatial modulation of superconductivity. This characteristic allows us to "write" a device whose electrical transport shows different temperature regimes and magnetic-field-matching effects that are characteristic of Josephson coupled weak links. This behavior illustrates the potential of the ferroelectric approach for the realization of high-temperature-superconducting devices.

  4. Effect of oxidation on base liquids of oil and synthetic-based drilling fluids at high pressure and high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Shahbazi, K.; Mehta, S.A.; Moore, R.G.; Ursenbach, M.G. [Calgary Univ., AB (Canada)

    2005-07-01

    Diesels and distillates are used as a base liquid for most oil-based drilling fluids in conventional drilling and as the liquid phase in gasified liquids in some underbalanced drilling operations. They are also used as friction reducing agents to free stuck pipes. It is important to understand the true downhole rheological properties because they affect equivalent circulating density, hole cleaning, barite sag, surge/swab pressures during tripping, pump pressure and bit hydraulics. Also, gelation and high viscosity are major concerns, particularly at high temperatures. An experimental study was conducted to evaluate the effect of oxidation on some base liquids for oil-based and synthetic-based drilling fluids at high pressures and high temperatures. Gas and liquid phases were characterized and the solid phase was measured along with viscosity measurements at temperatures and pressures ranging from 20 to 152 degrees C at atmospheric pressures to 103.4 MPa. The viscosity of the liquid samples after aging was compared with that of corresponding fresh samples. The results indicate that the degree of oxidation plays an important role in increasing the sample viscosity. The increase in viscosity depends on temperature, and is more significant at low temperatures. Agitation of samples during aging with air resulted in increased amounts of solid precipitation while lowering the viscosity of the liquid phase. This study demonstrated that oxidation has an important influence on rheological properties of the oil, because it affects the mobility of the oil and therefore the recovery factor. 11 refs., 7 tabs., 22 figs.

  5. Effects of W on microstructure and high-temperature oxidation behavior of ferritic stainless steel weldment

    Science.gov (United States)

    Ji, Yijie; Xie, Yuye; Zhu, Shuangchun; Yan, Biao

    2017-07-01

    With the promotion of fuel economy policy and automobile lightweight concept, ferritic stainless steels applied in vehicles’ exhaust hot end systems have been developed. This paper simulated the high-temperature environment at which the automobile exhaust system serviced in for high-temperature corrosion. Kinetic curves were conducted in isothermal environments at 1000∘C. X-ray diffraction, scanning electron microscope and energy dispersive spectrometer were used to study the oxidation behavior of ferritic stainless steels and the effects of tungsten (W) addition. The results show that, with increasing oxidation time, the rate of weight gains increase and the main failure is spalling of surface oxide layer. The addition of W has a complicated effect on the oxidation behavior of ferritic stainless steel weldment.

  6. High temperature battery. Hochtemperaturbatterie

    Energy Technology Data Exchange (ETDEWEB)

    Bulling, M.

    1992-06-04

    To prevent heat losses of a high temperature battery, it is proposed to make the incoming current leads in the area of their penetration through the double-walled insulating housing as thermal throttle, particularly spiral ones.

  7. Effect of quenching temperature on structure and properties of centrifugal casting high speed steel roll

    Directory of Open Access Journals (Sweden)

    Fu Hanguang

    2009-02-01

    Full Text Available The critical points and time-temperature-transformation (TTT curves of the isothermal transformation diagrams for a high-speed steel casting on a horizontal centrifugal casting machine had been determined experimentally in the study. The effects of quenching temperature on the microstructures and properties of centrifugal casting high speed steel (HSS roll has been investigated using scanning electron microscopy (SEM, light optical microscopy (LOM and X-ray diffraction (XRD as well as using tensile, impact, and hardness tests. The results show that the HSS roll has excellent hardenability and its matrix structure can be transformed into the martensite after being quenched in the sodium silicate solution. The retained austenite in the quenching structure increases and the hardness decreases when the quenching temperature exceeds 1,040℃. The tensile strength and impact toughness of HSS roll increase once the quenching temperature is raised from 980℃ to 1,040℃. However, the tensile strength and impact toughness have no signifi cant change when the quenching temperature exceeds 1,040℃. The HSS roll quenched at 1,040℃ exhibits excellent comprehensive mechanical properties.

  8. Effects of high temperature and film thicknesses on the texture evolution in Ag thin films

    Science.gov (United States)

    Eshaghi, F.; Zolanvari, A.

    2017-04-01

    In situ high-temperature X-ray diffraction techniques were used to study the effect of high temperatures (up to 600°C) on the texture evolution in silver thin films. Ag thin films with different thicknesses of 40, 80, 120 and 160nm were sputtered on the Si(100) substrates at room temperature. Then, microstructure of thin films was determined using X-ray diffraction. To investigate the influence of temperature on the texture development in the Ag thin films with different thicknesses, (111), (200) and (220) pole figures were evaluated and orientation distribution functions were calculated. Minimizing the total energy of the system which is affected by competition between surface and elastic strain energy was a key factor in the as-deposited and post annealed thin films. Since sputtering depositions was performed at room temperature and at the same thermodynamic conditions, the competition growth caused the formation of the {122} fiber texture in as-deposited Ag thin films. It was significantly observed that the post annealed Ag thin films showed {111} fiber texture varied with the thickness of thin films. Increasing thin film thickness from 40nm to 160nm led to decreasing the intensity of the {111} fiber texture.

  9. High temperature structural silicides

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, J.J.

    1997-03-01

    Structural silicides have important high temperature applications in oxidizing and aggressive environments. Most prominent are MoSi{sub 2}-based materials, which are borderline ceramic-intermetallic compounds. MoSi{sub 2} single crystals exhibit macroscopic compressive ductility at temperatures below room temperature in some orientations. Polycrystalline MoSi{sub 2} possesses elevated temperature creep behavior which is highly sensitive to grain size. MoSi{sub 2}-Si{sub 3}N{sub 4} composites show an important combination of oxidation resistance, creep resistance, and low temperature fracture toughness. Current potential applications of MoSi{sub 2}-based materials include furnace heating elements, molten metal lances, industrial gas burners, aerospace turbine engine components, diesel engine glow plugs, and materials for glass processing.

  10. High Temperature Electrolysis

    DEFF Research Database (Denmark)

    Elder, Rachael; Cumming, Denis; Mogensen, Mogens Bjerg

    2015-01-01

    High temperature electrolysis of carbon dioxide, or co-electrolysis of carbon dioxide and steam, has a great potential for carbon dioxide utilisation. A solid oxide electrolysis cell (SOEC), operating between 500 and 900. °C, is used to reduce carbon dioxide to carbon monoxide. If steam is also...... input to the cell then hydrogen is produced giving syngas. This syngas can then be further reacted to form hydrocarbon fuels and chemicals. Operating at high temperature gives much higher efficiencies than can be achieved with low temperature electrolysis. Current state of the art SOECs utilise a dense...

  11. The influence of the scale effect and high temperatures on the strength and strains of high performance concrete

    Directory of Open Access Journals (Sweden)

    Korsun Vladimyr Ivanovych

    2014-03-01

    Full Text Available The most effective way to reduce the structure mass, labor input and expenses for its construction is to use modern high-performance concrete of the classes С50/60… С90/105, which possess high physical and mathematic characteristics. One of the constraints for their implementation in mass construction in Ukraine is that in design standards there are no experimental data on the physical and mathematic properties of concrete of the classes more than С50/60. Also there are no exact statements on calculating reinforced concrete structures made of high-performance concretes.The authors present the results of experimental research of the scale effect and short-term and long-term heating up to +200 ° C influence on temperature and shrinkage strain, on strength and strain characteristics under compression and tensioning of high-strength modified concrete of class C70/85. The application of high performance concretes is challenging in the process of constructing buildings aimed at operating in high technological temperatures: smoke pipes, coolers, basins, nuclear power plants' protective shells, etc. Reducing cross-sections can lead to reducing temperature drops and thermal stresses in the structures.

  12. High Temperature QCD

    CERN Document Server

    Lombardo, M P

    2012-01-01

    I review recent results on QCD at high temperature on a lattice. Steady progress with staggered fermions and Wilson type fermions allow a quantitative description of hot QCD whose accuracy in many cases parallels that of zero temperature studies. Simulations with chiral quarks are coming of age, and togheter with theoretical developments trigger interesting developments in the analysis of the critical region. Issues related with the universality class of the chiral transition and the fate of the axial symmetry are discussed in the light of new numerical and analytical results. Transport coefficients and analysis of bottomonium spectra compare well with results of heavy ion collisions at RHIC and LHC. Model field theories, lattice simulations and high temperature systematic expansions help building a coherent picture of the high temperature phase of QCD. The (strongly coupled) Quark Gluon Plasma is heavily investigated, and asserts its role as an inspiring theoretical laboratory.

  13. Temperature and high pressure effects on the structural features of catalytic nanocomposites oxides by Raman spectroscopy.

    Science.gov (United States)

    da Silva, Antonio N; Pinto, Raffael C F; Freire, Paulo T C; Junior, Jose Alves L; Oliveira, Alcineia C; Filho, Josué M

    2015-03-05

    Structural characterizations of nanostructured oxides were studied by X-ray diffraction (XRD), Raman and infrared spectroscopy. The oxides catalysts namely, SnO2, ZrO2, CeO2, MnOx, Al2O3 and TiO2 were prepared by a nanocasting route and the effect of the temperature and pressure on the stability of the solids was evaluated. Raman spectra showed that ZrO2 and TiO2 exhibited phase transitions at moderate temperatures whereas CeO2, SnO2 and MnOx had an effective creation of defects in their structures upon annealing at elevated temperatures. The results suggested also that the effect of the temperature on the particles growth is related to the type of oxide. In this regard, phase transition by up to 600°C accelerated the sintering of ZrO2 and CeO2 grains compared to TiO2, SnO2 and MnOx counterparts. Under hydrostatic pressures lower than 10GPa, rutile TiO2 and tetragonal ZrO2 exhibited pressure induced phase transition whereas CeO2 and SnO2 were stable at pressures close to 15GPa. The experiments revealed that the nanostructured SnO2 oxide exhibited stable performance at relatively high temperatures without phase transition or sintering, being suitable to be used as catalysts in the range of temperature and pressure studied. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. High Temperature Aquifer Storage

    Science.gov (United States)

    Ueckert, Martina; Niessner, Reinhard; Baumann, Thomas

    2016-04-01

    Combined heat and power generation (CHP) is highly efficient because excess heat is used for heating and/or process energy. However, the demand of heat energy varies considerably throughout the year while the demand for electrical energy is rather constant. It seems economically and ecologically highly beneficial for municipalities and large power consumers such as manufacturing plants to store excess heat in groundwater aquifers and to recuperate this energy at times of higher demand. Within the project High Temperature Aquifer Storage, scientists investigate storage and recuperation of excess heat energy into the bavarian Malm aquifer. Apart from high transmissivity and favorable pressure gradients, the hydrochemical conditions are crucial for long-term operation. An enormous technical challenge is the disruption of the carbonate equilibrium - modeling results indicated a carbonate precipitation of 10 - 50 kg/d in the heat exchangers. The test included five injection pulses of hot water (60 °C up to 110 °C) and four tracer pulses, each consisting of a reactive and a conservative fluorescent dye, into a depth of about 300 m b.s.l. resp. 470 m b.s.l. Injection and production rates were 15 L/s. To achieve the desired water temperatures, about 4 TJ of heat energy were necessary. Electrical conductivity, pH and temperature were recorded at a bypass where also samples were taken. A laboratory container at the drilling site was equipped for analysing the concentration of the dyes and the major cations at sampling intervals of down to 15 minutes. Additional water samples were taken and analysed in the laboratory. The disassembled heat exchanger prooved that precipitation was successfully prevented by adding CO2 to the water before heating. Nevertheless, hydrochemical data proved both, dissolution and precipitation processes in the aquifer. This was also suggested by the hydrochemical modelling with PhreeqC and is traced back to mixture dissolution and changing

  15. Effect of acclimation to high ambient temperature of pigs selected for residual feed intake

    OpenAIRE

    Campos, Paulo Henrique Reis Furtado

    2011-01-01

    Thirty-six Large White castrate males belonging to two divergent lines in residual feed intake, with average initial body weight of 50.5 ± 0.9 kg and approximately 92 days of age, were used to evaluate the effects of acclimation to high temperature on the performance, thermoregulatory responses and blood parameters of pigs divergently selected for low and high residual feed intake. The experiment was conducted in two successive replicates of 18 animals each. The first replicate was composed b...

  16. High temperature superconducting materials

    Energy Technology Data Exchange (ETDEWEB)

    Alario-Franco, M.A. [Universidad Complutense de Madrid (Spain). Facultad de Ciencias Quimicas

    1995-02-01

    The perovskite structure is the basis of all known high-temperature superconducting materials. Many of the most successful (highest T{sub c}) materials are based on mercury and thallium phases but, due to the high toxicity of the component compounds effort has been invested in the substitution of these elements with silver. Progress is reviewed. (orig.)

  17. Trace elements in migrating high-temperature fluids: Effects of diffusive exchange with the adjoining solid

    Science.gov (United States)

    Kenyon, Patricia M.

    1993-01-01

    Trace element concentrations and isotopic ratios are frequently used to study the behavior of high-temperature fluids in both metamorphic and igneous systems. Many theoretical formulations of the effects of fluid migration on trace elements have assumed instantaneous reequilibration between the migrating fluid and the solid material through which it is passing. This paper investigates the additional effects which arise when equilibration is not instantaneous due to a limited rate of diffusion in the solid, using an analytical steady state solution to a set of partial differential equations describing the exchange of trace elements between the fluid and the solid during the migration of the fluid.

  18. Sodium effects on mechanical performance and consideration in high temperature structural design for advanced reactors

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K., E-mail: natesan@anl.go [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Li Meimei; Chopra, O.K.; Majumdar, S. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2009-07-15

    Sodium environmental effects are key limiting factors in the high temperature structural design of advanced sodium-cooled reactors. A guideline is needed to incorporate environmental effects in the ASME design rules to improve the performance reliability over long operating times. This paper summarizes the influence of sodium exposure on mechanical performance of selected austenitic stainless and ferritic/martensitic steels. Focus is on Type 316SS and mod.9Cr-1Mo. The sodium effects were evaluated by comparing the mechanical properties data in air and sodium. Carburization and decarburization were found to be the key factors that determine the tensile and creep properties of the steels. A beneficial effect of sodium exposure on fatigue life was observed under fully reversed cyclic loading in both austenitic stainless steels and ferritic/martensitic steels. However, when hold time was applied during cyclic loading, the fatigue life was significantly reduced. Based on the mechanical performance of the steels in sodium, consideration of sodium effects in high temperature structural design of advanced fast reactors is discussed.

  19. Effects of high temperature stress at different development stages on soybean isoflavone and tocopherol concentrations.

    Science.gov (United States)

    Chennupati, Pratyusha; Seguin, Philippe; Liu, Wucheng

    2011-12-28

    Soybean contains a range of compounds with putative health benefits including isoflavones and tocopherols. A study was conducted to determine the effects on these compounds of high temperature stress imposed at specific development stages [i.e., none, pre-emergence, vegetative, early reproductive (R1-4), late-reproductive (R5-8), or all stages]. Two cultivars (AC Proteina and OAC Champion) were grown in growth chambers set at contrasting temperatures [i.e., stress conditions of 33/25 °C (day/night temperature) and control conditions of 23/15 °C] in order to generate these treatments. Isoflavone and tocopherol concentrations in mature seeds were determined using high-performance liquid chromatography. In both cultivars isoflavone response was greatest when stress occurred during the R5-8 stages and during all development stages, these treatments reducing total isoflavone concentration by an average of 85% compared to the control. Stress imposed at other stages also affected isoflavone concentration although the response was smaller. For example, stress during the vegetative stages reduced total isoflavones by 33% in OAC Champion. Stress imposed pre-emergence had an opposite effect increasing daidzein concentration by 24% in AC Proteina. Tocopherol concentrations were affected the most when stress was imposed during all stages of development, followed by stress restricted to stages R5-8; response to stress during other stages was limited. The specific response of tocopherols differed, α-tocopherol being increased by high temperature by as much as 752%, the reverse being observed for δ-tocopherol and γ-tocopherol. The present study demonstrates that while isoflavone and tocopherol concentrations in soybeans are affected the most by stress occurring during seed formation, concentrations can also be affected by stress occurring at other stages including stages as early as pre-emergence.

  20. Cost Effective Growth of High Temperature Piezoelectrics for Adaptive Flow Control Actuators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies, Inc. in collaboration with The Pennsylvania State University propose to develop new families of high temperature piezoelectric materials for...

  1. High temperature storage loop :

    Energy Technology Data Exchange (ETDEWEB)

    Gill, David Dennis; Kolb, William J.

    2013-07-01

    A three year plan for thermal energy storage (TES) research was created at Sandia National Laboratories in the spring of 2012. This plan included a strategic goal of providing test capability for Sandia and for the nation in which to evaluate high temperature storage (>650ÀC) technology. The plan was to scope, design, and build a flow loop that would be compatible with a multitude of high temperature heat transfer/storage fluids. The High Temperature Storage Loop (HTSL) would be reconfigurable so that it was useful for not only storage testing, but also for high temperature receiver testing and high efficiency power cycle testing as well. In that way, HTSL was part of a much larger strategy for Sandia to provide a research and testing platform that would be integral for the evaluation of individual technologies funded under the SunShot program. DOEs SunShot program seeks to reduce the price of solar technologies to 6/kWhr to be cost competitive with carbon-based fuels. The HTSL project sought to provide evaluation capability for these SunShot supported technologies. This report includes the scoping, design, and budgetary costing aspects of this effort

  2. Alloying effects on the high-temperature oxidation resistance of Cr-Cr{sub 2}Nb

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, P.F.; DeVan, J.H.

    1994-09-01

    Alloying effects on the high-temperature oxidation resistance of Cr-Cr{sub 2}Nb were examined on the basis of isothermal exposures to air at 950 C. Additions of either Re and Al or Fe, Ni, and Al had relatively little effect on weight gains relative to the Cr-6% Nb binary alloy. One alloying element that improved the mechanical behavior of Cr-Cr{sub 2}Nb alloys substantially increased the oxidation rates and spallation susceptibilities of Cr-6 and -12% Nb alloys. However, the addition of another element completely offset these deleterious effects. The presence of this latter element resulted in the best overall oxidation behavior (in terms of both weight gains and spallation tendencies) of all Cr-Cr{sub 2}Nb compositions. Its beneficial effect can be attributed to improvement in the oxidation resistance of the Cr-rich phase.

  3. Renormalization effects and phonon density of states in high temperature superconductors

    Directory of Open Access Journals (Sweden)

    Vinod Ashokan

    2013-02-01

    Full Text Available Using the versatile double time thermodynamic Green's function approach based on many body theory the renormalized frequencies, phonon energy line widths, shifts and phonon density of states (PDOS are investigated via a newly formulated Hamiltonian (does not include BCS type Hamiltonian that includes the effects of electron-phonon, anharmonicities and that of isotopic impurities. The automatic appearance of pairons, temperature, impurity and electron-phonon coupling of renormalized frequencies, widths, shifts and PDOS emerges as a characteristic feature of present theory. The numerical investigations on PDOS for the YBa2Cu3O7 − δ crystal predicts several new feature of high temperature superconductors (HTS and agreements with experimental observations.

  4. The effect of high correlated colour temperature office lighting on employee wellbeing and work performance

    Directory of Open Access Journals (Sweden)

    Tomkins Susannah C

    2007-01-01

    Full Text Available Abstract Background The effects of lighting on the human circadian system are well-established. The recent discovery of 'non-visual' retinal receptors has confirmed an anatomical basis for the non-image forming, biological effects of light and has stimulated interest in the use of light to enhance wellbeing in the corporate setting. Methods A prospective controlled intervention study was conducted within a shift-working call centre to investigate the effect of newly developed fluorescent light sources with a high correlated colour temperature (17000 K upon the wellbeing, functioning and work performance of employees. Five items of the SF-36 questionnaire and a modification of the Columbia Jet Lag scale, were used to evaluate employees on two different floors of the call centre between February and May 2005. Questionnaire completion occurred at baseline and after a three month intervention period, during which time one floor was exposed to new high correlated colour temperature lighting and the other remained exposed to usual office lighting. Two sided t-tests with Bonferroni correction for type I errors were used to compare the characteristics of the two groups at baseline and to evaluate changes in the intervention and control groups over the period of the study. Results Individuals in the intervention arm of the study showed a significant improvement in self-reported ability to concentrate at study end as compared to those within the control arm (p Conclusion High correlated colour temperature fluorescent lights could provide a useful intervention to improve wellbeing and productivity in the corporate setting, although further work is necessary in quantifying the magnitude of likely benefits.

  5. High temperature superconductivity: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Bedell, K.S.; Coffey, D. (Los Alamos National Lab., NM (USA)); Meltzer, D.E. (Florida Univ., Gainesville, FL (USA)); Pines, D. (Illinois Univ., Urbana, IL (USA)); Schrieffer, J.R. (California Univ., Santa Barbara, CA (USA)) (eds.)

    1990-01-01

    This book is the result of a symposium at Los Alamos in 1989 on High Temperature Superconductivity. The topics covered include: phenomenology, quantum spin liquids, spin space fluctuations in the insulating and metallic phases, normal state properties, and numerical studies and simulations. (JF)

  6. Life at High Temperatures

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 9. Life at High Temperatures. Ramesh Maheshwari. General Article Volume 10 Issue 9 September 2005 pp 23-36. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/010/09/0023-0036. Keywords.

  7. AC Losses and Their Thermal Effect in High Temperature Superconducting Machines

    DEFF Research Database (Denmark)

    Song, Xiaowei (Andy); Mijatovic, Nenad; Zou, Shengnan

    2015-01-01

    In transient operations or fault conditions, high temperature superconducting (HTS) machines suffer AC losses which have an influence on the thermal stability of superconducting windings. In this paper, a method to calculate AC losses and their thermal effect in HTS machines is presented....... The method consists of three sub-models that are coupled only in one direction. The magnetic field distribution is first solved in a machine model, assuming a uniform current distribution in HTS windings. The magnetic fields on the boundaries are then used as inputs for an AC loss model which has...... an HTS machine and its cooling system....

  8. Effect of dissolved hydrogen on corrosion of 316NG stainless steel in high temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Lijin [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang City 110819 (China); Peng, Qunjia, E-mail: qunjiapeng@imr.ac.cn [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Zhang, Zhiming [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Shoji, Tetsuo [Frontier Research Initiative, New Industry Creation Hatchery Center, Tohoku University, 6-6-10, Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Han, En-Hou; Ke, Wei [Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang City 110016 (China); Wang, Lei [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang City 110819 (China)

    2015-12-15

    Highlights: • Dissolved hydrogen (DH) effect on corrosion of stainless steel in high temperature water. • Increasing DH caused decrease of Cr- but increase of Fe-concentrations in the inner oxide layer. • Concentration gradient of Cr and Fe in the inner oxide layer. • DH effect was attributed to the accelerated diffusion of Fe ion in the inner oxide layer. - Abstract: Characterizations of oxide films formed on 316 stainless steel in high temperature, hydrogenated water were conducted. The results show the oxide film consists of an outer layer with oxide particles of Fe–Ni spinel and hematite, and an inner continuous layer of Fe–Cr–Ni spinel. Increasing dissolved hydrogen (DH) concentrations causes decrease of Cr- and increase of Fe-concentrations in the inner layer. A continuous decrease of Cr- and increase of Fe-concentrations was observed from the surface of the inner layer to the oxide/substrate interface. The DH effect is attributed to the enhanced diffusion of Fe ions in the oxide film by hydrogen.

  9. Topological Hubbard model and its high-temperature quantum Hall effect.

    Science.gov (United States)

    Neupert, Titus; Santos, Luiz; Ryu, Shinsei; Chamon, Claudio; Mudry, Christopher

    2012-01-27

    The quintessential two-dimensional lattice model that describes the competition between the kinetic energy of electrons and their short-range repulsive interactions is the repulsive Hubbard model. We study a time-reversal symmetric variant of the repulsive Hubbard model defined on a planar lattice: Whereas the interaction is unchanged, any fully occupied band supports a quantized spin Hall effect. We show that at 1/2 filling of this band, the ground state develops spontaneously and simultaneously Ising ferromagnetic long-range order and a quantized charge Hall effect when the interaction is sufficiently strong. We ponder on the possible practical applications, beyond metrology, that the quantized charge Hall effect might have if it could be realized at high temperatures and without external magnetic fields in strongly correlated materials.

  10. Temperature optimization of high con

    Directory of Open Access Journals (Sweden)

    M. Sabry

    2016-06-01

    Full Text Available Active cooling is essential for solar cells operating under high optical concentration ratios. A system comprises four solar cells that are in thermal contact on top of a copper tube is proposed. Water is flowing inside the tube in order to reduce solar cells temperature for increasing their performance. Computational Fluid Dynamics (CFD simulation of such system has been performed in order to investigate the effect of water flow rate, tube internal diameter, and convective heat transfer coefficient on the temperature of the solar cells. It is found that increasing convective heat transfer coefficient has a significant effect on reducing solar cells temperatures operating at low flow rates and high optical concentration ratios. Also, a further increase of water flow rate has no effect on reducing cells temperatures.

  11. High pressure Moissanite-anvil cells for the low temperature Hall effect measurements of oxide superconductors

    Science.gov (United States)

    Yomo, Shusuke; Tozer, Stanley

    2013-03-01

    The Hall effect was successfully measured for a single crystal of high temperature superconductor in a Moissanite-anvil clamp cell up to 5 GPa, with proper arrangement of lead wires and a sample. Zylon gasket, good in electrical insulation, worked well up to 5 GPa. The 30-40 % increase of the clamped pressure was observed during cooling to below 60 K. The appreciable pressure effect of the a-b plane Hall coefficient was observed and negative for La2 - x Srx CuO4 with x = 0.090. The result is discussed with those for sintered samples and those studied with a different pressurizing method. Thanks are due to Visiting Scientist Program, NHMFL, and NNSA grant DE-FG52-03NA00066.

  12. High temperature effects in moving shock reflection with protruding Mach stem

    Directory of Open Access Journals (Sweden)

    Xiaofeng Shi

    2016-09-01

    Full Text Available The influence of high temperature effects on the protrusion of Mach stem in strong shock reflection over a wedge was numerically investigated. A two-dimensional inviscid solver applies finite volume method and unstructured quadrilateral grids were employed to simulate the flow. Theoretical analysis was also conducted to understand the phenomenon. Both numerical and theoretical results indicate a wall-jet penetrating forward is responsible for the occurrence of Mach stem protrusion. The protrusion degree seems to depend on the thermal energy buffer capacity of the testing gas. Approaches to increase the energy buffer capacity, such as vibrational relaxation, molecular dissociation, and increase of frozen heat capacity, all tend to escalate the protrusion effect.

  13. Effect of Water Vapor on High-Temperature Corrosion under Conditions Mimicking Biomass Firing

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

    2015-01-01

    The variable flue gas composition in biomass-fired plants, among other parameters, contributes to the complexityof high-temperature corrosion of materials. Systematic parameter studies are thus necessary to understand the underlyingcorrosion mechanisms. This paper investigates the effect of water...... atmospherecontaining either 3 or 13 vol % H2O vapor. Comprehensive characterization of the corrosion products was carried out by thecomplementary use of microscopic, spectroscopic, and diffraction-based techniques. To evaluate the effect of the exposure time,results were compared to previous results with longer...... isothermal exposure over 168 h and indicated that the development of aNi-rich layer as a result of selective attack was time-dependent. The increase in the water vapor decreased the measurablecorrosion attack, and in addition, decreased sulfation was observed. Results from the current investigation and from...

  14. Effect of temperature on the progamic phase in high-mountain plants.

    Science.gov (United States)

    Steinacher, G; Wagner, J

    2012-03-01

    Progamic processes are particularly temperature-sensitive and, in lowland plants, are usually drastically reduced below 10 °C and above 30 °C. Little is known about how effectively sexual processes of mountain plants function under the large temperature fluctuations at higher altitudes. The present study examines duration and thermal thresholds for progamic processes in six common plant species (Cerastium uniflorum, Gentianella germanica, Ranunculus alpestris, R. glacialis, Saxifraga bryoides, S. caesia) from different altitudinal zones in the European Alps. Whole plants were collected from natural sites shortly before anthesis and kept in a climate chamber until further processing. Flowers with receptive stigmas were hand-pollinated with allopollen and exposed to controlled temperatures between -2 and 40 °C. Pollen performance (adhesion to the stigma, germination, tube growth, fertilisation) was quantitatively analysed, using the aniline blue fluorescence method. Pollen adhesion was possible from -2 to 40 °C. Pollen germination and tube growth occurred from around 0 to 35 °C in most species. Fertilisation was observed from 5 to 30-32 °C (0-35 °C in G. germanica). The progamic phase was shortest in G. germanica (2 h at 30 °C, 12 h at 5 °C, 24 h at 0 °C), followed by R. glacialis (first fertilisation after 2 h at 30 °C, 18 h at 5 °C). In the remaining species, first fertilisation usually occurred after 4-6 h at 30 °C and after 24-30 h at 5 °C. Thus, mountain plants show remarkably flexible pollen performance over a wide temperature range and a short progamic phase, which may be essential for successful reproduction in the stochastic high-mountain climate. © 2011 German Botanical Society and The Royal Botanical Society of the Netherlands.

  15. High Temperature Piezoelectric Drill

    Science.gov (United States)

    Bao, Xiaoqi; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Shrout, Tom

    2012-01-01

    Venus is one of the planets in the solar systems that are considered for potential future exploration missions. It has extreme environment where the average temperature is 460 deg C and its ambient pressure is about 90 atm. Since the existing actuation technology cannot maintain functionality under the harsh conditions of Venus, it is a challenge to perform sampling and other tasks that require the use of moving parts. Specifically, the currently available electromagnetic actuators are limited in their ability to produce sufficiently high stroke, torque, or force. In contrast, advances in developing electro-mechanical materials (such as piezoelectric and electrostrictive) have enabled potential actuation capabilities that can be used to support such missions. Taking advantage of these materials, we developed a piezoelectric actuated drill that operates at the temperature range up to 500 deg C and the mechanism is based on the Ultrasonic/Sonic Drill/Corer (USDC) configuration. The detailed results of our study are presented in this paper

  16. Effects of carbon content on high-temperature mechanical and thermal fatigue properties of high-boron austenitic steels

    Directory of Open Access Journals (Sweden)

    Xiang Chen

    2016-01-01

    Full Text Available High-temperature mechanical properties of high-boron austenitic steels (HBASs were studied at 850 °C using a dynamic thermal-mechanical simulation testing machine. In addition, the thermal fatigue properties of the alloys were investigated using the self-restraint Uddeholm thermal fatigue test, during which the alloy specimens were cycled between room temperature and 800°C. Stereomicroscopy and scanning electron microscopy were used to study the surface cracks and cross-sectional microstructure of the alloy specimens after the thermal fatigue tests. The effects of carbon content on the mechanical properties at room temperature and high-temperature as well as thermal fatigue properties of the HBASs were also studied. The experimental results show that increasing carbon content induces changes in the microstructure and mechanical properties of the HBASs. The boride phase within the HBAS matrix exhibits a round and smooth morphology, and they are distributed in a discrete manner. The hardness of the alloys increases from 239 (0.19wt.% C to 302 (0.29wt.% C and 312 HV (0.37wt.% C; the tensile yield strength at 850 °C increases from 165.1 to 190.3 and 197.1 MPa; and the compressive yield strength increases from 166.1 to 167.9 and 184.4 MPa. The results of the thermal fatigue tests (performed for 300 cycles from room temperature to 800 °C indicate that the degree of thermal fatigue of the HBAS with 0.29wt.% C (rating of 2–3 is superior to those of the alloys with 0.19wt.% (rating of 4–5 and 0.37wt.% (rating of 3–4 carbon. The main cause of this difference is the ready precipitation of M23(C,B6-type borocarbides in the alloys with high carbon content during thermal fatigue testing. The precipitation and aggregation of borocarbide particles at the grain boundaries result in the deterioration of the thermal fatigue properties of the alloys.

  17. High temperature materials and mechanisms

    CERN Document Server

    2014-01-01

    The use of high-temperature materials in current and future applications, including silicone materials for handling hot foods and metal alloys for developing high-speed aircraft and spacecraft systems, has generated a growing interest in high-temperature technologies. High Temperature Materials and Mechanisms explores a broad range of issues related to high-temperature materials and mechanisms that operate in harsh conditions. While some applications involve the use of materials at high temperatures, others require materials processed at high temperatures for use at room temperature. High-temperature materials must also be resistant to related causes of damage, such as oxidation and corrosion, which are accelerated with increased temperatures. This book examines high-temperature materials and mechanisms from many angles. It covers the topics of processes, materials characterization methods, and the nondestructive evaluation and health monitoring of high-temperature materials and structures. It describes the ...

  18. High temperature superconductors

    CERN Document Server

    Paranthaman, Parans

    2010-01-01

    This essential reference provides the most comprehensive presentation of the state of the art in the field of high temperature superconductors. This growing field of research and applications is currently being supported by numerous governmental and industrial initiatives in the United States, Asia and Europe to overcome grid energy distribution issues. The technology is particularly intended for densely populated areas. It is now being commercialized for power-delivery devices, such as power transmission lines and cables, motors and generators. Applications in electric utilities include current limiters, long transmission lines and energy-storage devices that will help industries avoid dips in electric power.

  19. Effects of reproductive status and high ambient temperatures on the body temperature of a free-ranging basoendotherm.

    Science.gov (United States)

    Levesque, Danielle L; Lobban, Kerileigh D; Lovegrove, Barry G

    2014-12-01

    Tenrecs (Order Afrosoricida) exhibit some of the lowest body temperatures (T b) of any eutherian mammal. They also have a high level of variability in both active and resting T bs and, at least in cool temperatures in captivity, frequently employ both short- and long-term torpor. The use of heterothermy by captive animals is, however, generally reduced during gestation and lactation. We present data long-term T b recordings collected from free-ranging S. setosus over the course of two reproductive seasons. In general, reproductive females had slightly higher (~32 °C) and less variable T b, whereas non-reproductive females and males showed both a higher propensity for torpor as well as lower (~30.5 °C) and more variable rest-phase T bs. Torpor expression defined using traditional means (using a threshold or cut-off T b) was much lower than predicted based on the high degree of heterothermy in captive tenrecs. However, torpor defined in this manner is likely to be underestimated in habitats where ambient temperature is close to T b. Our results caution against inferring metabolic states from T b alone and lend support to the recent call to define torpor in free-ranging animals based on mechanistic and not descriptive variables. In addition, lower variability in T b observed during gestation and lactation confirms that homeothermy is essential for reproduction in this species and probably for basoendothermic mammals in general. The relatively low costs of maintaining homeothermy in a sub-tropical environment might help shed light on how homeothermy could have evolved incrementally from an ancestral heterothermic condition.

  20. Effect of High-Temperature Curing Methods on the Compressive Strength Development of Concrete Containing High Volumes of Ground Granulated Blast-Furnace Slag

    Directory of Open Access Journals (Sweden)

    Wonsuk Jung

    2017-01-01

    Full Text Available This paper investigates the effect of the high-temperature curing methods on the compressive strength of concrete containing high volumes of ground granulated blast-furnace slag (GGBS. GGBS was used to replace Portland cement at a replacement ratio of 60% by binder mass. The high-temperature curing parameters used in this study were the delay period, temperature rise, peak temperature (PT, peak period, and temperature down. Test results demonstrate that the compressive strength of the samples with PTs of 65°C and 75°C was about 88% higher than that of the samples with a PT of 55°C after 1 day. According to this investigation, there might be optimum high-temperature curing conditions for preparing a concrete containing high volumes of GGBS, and incorporating GGBS into precast concrete mixes can be a very effective tool in increasing the applicability of this by-product.

  1. Effect of layer thickness on the high temperature mechanical properties of Al/SiC nanolaminates

    Energy Technology Data Exchange (ETDEWEB)

    Lotfian, S. [IMDEA Materials Institute, c/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Mayer, C.; Chawla, N. [Materials Science and Engineering, Arizona State University, Tempe, AZ 85287-6106 (United States); Llorca, J. [IMDEA Materials Institute, c/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Department of Materials Science, Polytechnic University of Madrid, E.T.S. de Ingenieros de Caminos, 28040 Madrid (Spain); Misra, A.; Baldwin, J.K. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Molina-Aldareguía, J.M., E-mail: jon.molina@imdea.org [IMDEA Materials Institute, c/Eric Kandel 2, 28906 Getafe, Madrid (Spain)

    2014-11-28

    Composite laminates on the nanoscale have shown superior hardness and toughness, but little is known about their high temperature behavior. The mechanical properties (elastic modulus and hardness) were measured as a function of temperature by means of nanoindentation in Al/SiC nanolaminates, a model metal–ceramic nanolaminate fabricated by physical vapor deposition. The influence of the Al and SiC volume fraction and layer thicknesses was determined between room temperature and 150 °C and, the deformation modes were analyzed by transmission electron microscopy, using a focused ion beam to prepare cross-sections through selected indents. It was found that ambient temperature deformation was controlled by the plastic flow of the Al layers, constrained by the SiC, and the elastic bending of the SiC layers. The reduction in hardness with temperature showed evidence of the development of interface-mediated deformation mechanisms, which led to a clear influence of layer thickness on the hardness. - Highlights: • The mechanical behavior of Al/SiC nanolaminates was measured between 28 °C and 150 °C. • Room temperature hardness was controlled by the volume fraction of the constituents. • The hardness of all the nanolaminates decreased rapidly with temperature. • Reduction of hardness with temperature increased as the interface density increased.

  2. The Effects of Radiation and Thermal Stability of Sm-Co High Temperature Magnets For High Power Ion Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Since high temperature Sm-Co based magnets were developed, a number of new applications have been introduced. NASA?s Xe+ ion propulsion engine used in Deep Space I...

  3. Photosynthetic temperature responses of tree species in Rwanda: evidence of pronounced negative effects of high temperature in montane rainforest climax species.

    Science.gov (United States)

    Vårhammar, Angelica; Wallin, Göran; McLean, Christopher M; Dusenge, Mirindi Eric; Medlyn, Belinda E; Hasper, Thomas B; Nsabimana, Donat; Uddling, Johan

    2015-05-01

    The sensitivity of photosynthetic metabolism to temperature has been identified as a key uncertainty for projecting the magnitude of the terrestrial feedback on future climate change. While temperature responses of photosynthetic capacities have been comparatively well investigated in temperate species, the responses of tropical tree species remain unexplored. We compared the responses of seedlings of native cold-adapted tropical montane rainforest tree species with those of exotic warm-adapted plantation species, all growing in an intermediate temperature common garden in Rwanda. Leaf gas exchange responses to carbon dioxide (CO2 ) at different temperatures (20-40°C) were used to assess the temperature responses of biochemical photosynthetic capacities. Analyses revealed a lower optimum temperature for photosynthetic electron transport rates than for Rubisco carboxylation rates, along with lower electron transport optima in the native cold-adapted than in the exotic warm-adapted species. The photosynthetic optimum temperatures were generally exceeded by daytime peak leaf temperatures, in particular in the native montane rainforest climax species. This study thus provides evidence of pronounced negative effects of high temperature in tropical trees and indicates high susceptibility of montane rainforest climax species to future global warming. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  4. High temperature processing effects on the properties of fowl meat gels.

    Science.gov (United States)

    Voller-Reasonover, L; Han, I Y; Acton, J C; Titus, T C; Bridges, W C; Dawson, P L

    1997-05-01

    The effects of three moisture levels (0, 10, and 20% added water) and three processing temperatures (115.6, 121.1, and 126.7 C) on texture and collagen solubilization of fowl meat gels were examined. Meat gels were formulated from spent fowl breast meat that were cooked in water (71.1 C internal temperature) prior to heat processing. The water-cooked gels were heat processed at the three temperatures to an F0 value of 6.0 (Z value = 10 C). The addition of 20% water resulted in a reduction of the soluble collagen compared to the 10% water-added treatment. The lowest processing temperature increased the soluble collagen compared to the highest processing temperature. Shear stress and hardness decreased as the amount of added water was increased; and the lowest processing temperature resulted in the lowest hardness values. The increase in soluble collagen parallels the decrease in hardness in the samples processed at the lowest temperature. Because each sample was processed to equivalent F values, the lowest processing temperature had the longest exposure time (26 min at 115.6 C, 12 min at 121.1 C, and 6 min at 126.7 C). The longer exposure to moist heat allowed for greater collagen solubilization and lower hardness values. The 0% added-water treatment had the highest yield from before and after heat processing. However the 10% water-added samples had the greatest overall water retention when each treatment was placed on an equal level of initial water content. Furthermore, the highest processing temperature (shortest processing time) resulted in the greatest yield and moisture retention compared to the other processing temperatures.

  5. Effects of High-Temperature-Pressure Polymerized Resin-Infiltrated Ceramic Networks on Oral Stem Cells.

    Directory of Open Access Journals (Sweden)

    Mathilde Tassin

    Full Text Available The development of CAD-CAM techniques called for new materials suited to this technique and offering a safe and sustainable clinical implementation. The infiltration of resin in a ceramic network under high pressure and high temperature defines a new class of hybrid materials, namely polymer infiltrated ceramics network (PICN, for this purpose which requires to be evaluated biologically. We used oral stem cells (gingival and pulpal as an in vitro experimental model.Four biomaterials were grinded, immersed in a culture medium and deposed on stem cells from dental pulp (DPSC and gingiva (GSC: Enamic (VITA®, Experimental Hybrid Material (EHM, EHM with initiator (EHMi and polymerized Z100™ composite material (3M®. After 7 days of incubation; viability, apoptosis, proliferation, cytoskeleton, inflammatory response and morphology were evaluated in vitro.Proliferation was insignificantly delayed by all the tested materials. Significant cytotoxicity was observed in presence of resin based composites (MTT assay, however no detectable apoptosis and some dead cells were detected like in PICN materials. Cell morphology, major cytoskeleton and extracellular matrix components were not altered. An intimate contact appeared between the materials and cells.The three new tested biomaterials did not exhibit adverse effects on oral stem cells in our experimental conditions and may be an interesting alternative to ceramics or composite based CAD-CAM blocks.

  6. HIgh Temperature Photocatalysis over Semiconductors

    Science.gov (United States)

    Westrich, Thomas A.

    Due in large part to in prevalence of solar energy, increasing demand of energy production (from all sources), and the uncertain future of petroleum energy feedstocks, solar energy harvesting and other photochemical systems will play a major role in the developing energy market. This dissertation focuses on a novel photochemical reaction process: high temperature photocatalysis (i.e., photocatalysis conducted above ambient temperatures, T ≥ 100°C). The overarching hypothesis of this process is that photo-generated charge carriers are able to constructively participate in thermo-catalytic chemical reactions, thereby increasing catalytic rates at one temperature, or maintaining catalytic rates at lower temperatures. The photocatalytic oxidation of carbon deposits in an operational hydrocarbon reformer is one envisioned application of high temperature photocatalysis. Carbon build-up during hydrocarbon reforming results in catalyst deactivation, in the worst cases, this was shown to happen in a period of minutes with a liquid hydrocarbon. In the presence of steam, oxygen, and above-ambient temperatures, carbonaceous deposits were photocatalytically oxidized over very long periods (t ≥ 24 hours). This initial experiment exemplified the necessity of a fundamental assessment of high temperature photocatalytic activity. Fundamental understanding of the mechanisms that affect photocatalytic activity as a function of temperatures was achieved using an ethylene photocatalytic oxidation probe reaction. Maximum ethylene photocatalytic oxidation rates were observed between 100 °C and 200 °C; the maximum photocatalytic rates were approximately a factor of 2 larger than photocatalytic rates at ambient temperatures. The loss of photocatalytic activity at temperatures above 200 °C is due to a non-radiative multi-phonon recombination mechanism. Further, it was shown that the fundamental rate of recombination (as a function of temperature) can be effectively modeled as a

  7. The effect of Co-firing with Straw and Coal on High Temperature Corrosion

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Frandsen, Flemming; Larsen, OH

    2001-01-01

    chloride from the deposit thus chlorination is not a corrosion form that is seen. An increase in straw share from 10 % to 20 % (% energy basis) gave a higher amount of potassium sulphate in the ash and consequently greater amount of sulphidation. At high metal and flue gas temperatures, low temperature hot...... chloride deposited onto superheater sections which causes accelerated corrosion by chlorination. A field investigation at Midtkraft Studstrupværket in Denmark has been undertaken where coal with 10% straw and 20% straw (% energy basis) has been used as fuel for up to 3000 hours. The study was undertaken by......: a) the exposure of metal rings on water/air cooled probes, and b) the exposure of a range of materials built into the existing superheaters. A range of austenitic and ferritic steels was exposed in the steam temperature region of 520-580°C. The flue gas temperature ranged from 925-1100°C...

  8. High Temperature Hybrid Elastomers

    Science.gov (United States)

    Drake, Kerry Anthony

    Conventional high temperature elastomers are produced by chain polymerization of olefinic or fluorinated olefinic monomers. Ultimate thermal stabilities are limited by backbone bond strengths, lower thermal stability of cross-link sites relative to backbone bonds, and depolymerization or "unzipping" at high temperatures. In order to develop elastomers with enhanced thermal stability, hybrid thermally cross-linkable polymers that consisted only of organic-inorganic and aromatic bonds were synthesized and evaluated. The addition of phenylethynyl or phenylacetylinic functional groups to these polymers resulted in conversion of the polymers into high temperature elastomers when cross-linked by thermal curing. Polyphenyoxydiphenylsilanes were synthesized via several different condensation reactions. Results of these synthetic reactions, which utilized both hydroquinone and biphenol as monomers, were systematically evaluated to determine the optimal synthetic conditions for subsequent endcapping reactions. It was determined that dichlorodiphenylsilane condensations with biphenol in toluene or THF were best suited for this work. Use of excess dichlorodiphenylsilane yielded polymers of appropriate molecular weights with terminal reactive chlorosilane groups that could be utilized for coupling with phenylethynyl reagents in a subsequent reaction. Two new synthetic routes were developed to endcap biphenoxysilanes with ethynyl containing substituents, to yield polymers with cross-linkable end groups. Endcapping by lithiumphenylacetylide and 4[(4-fluorophenylethynyl))phenol yielded two new polymers that could be thermally cross-linked on heating above 300 °C. Successful endcapping was verified chemically by 13C NMR, FTIR and Raman analysis. Exothermic peaks consistent with ethynyl curing reactions were observed in endcapped polymers by DSC. A new diacetylinic polymer was prepared through reaction of 4,4'-buta-1,3-diyne-1,4-diyldiphenol and dichlorodiphenylsilane. This

  9. High-Temperature Superconductors

    CERN Document Server

    Saxena, Ajay Kumar

    2012-01-01

    This book presents the current knowledge about superconductivity in high Tc cuprate superconductors. There is a large scientific interest and great potential for technological applications. The book discusses all the aspects related to all families of cuprate superconductors discovered so far. Beginning with the phenomenon of superconductivity, the book covers: the structure of cuprate HTSCs, critical currents, flux pinning, synthesis of HTSCs, proximity effect and SQUIDs, possible applications of high Tc superconductors and theories of superconductivity. Though a high Tc theory is still awaited, this book describes the present scenario and BCS and RVB theories. The second edition was  significantly extended by including film-substrate lattice matching and buffer layer considerations in thin film HTSCs, brick-wall microstructure in the epitaxial films, electronic structure of the CuO2 layer in cuprates, s-wave and d-wave coupling in HTSCs and possible scenarios of theories of high Tc superconductivity.

  10. Irreversibility effects in piezoelectric wafer active sensors after exposure to high temperature

    Science.gov (United States)

    Faisal Haider, Mohammad; Giurgiutiu, Victor; Lin, Bin; Yu, Lingyu

    2017-09-01

    This paper presents an experimental and analytical study of irreversible change in piezoelectric wafer active sensor (PWAS) electromechanical (E/M) impedance and admittance signature under high temperature exposure. After elevated to high temperatures, change in the material properties of PWAS can be quantified through irreversible changes in its E/M impedance and admittance signature. For the experimental study, circular PWAS transducers were exposed to temperatures between 50 °C and 250 °C at 50 °C intervals. E/M impedance and admittance data were obtained before and after each heating cycle. Irreversible temperature sensitivity of PWAS resonance and anti-resonance frequency was estimated as 0.0246 kHz °C-1 and 0.0327 kHz °C-1 respectively. PWAS transducer material properties relevant to impedance or admittance signature such as dielectric constant, dielectric loss factor, mechanical loss factor, and in plane piezoelectric constant were determined experimentally at room temperature before and after the elevated temperature tests. The in-plane piezoelectric coefficient was measured by using optical-fiber strain transducer system. It was found that the dielectric constant and in-plane piezoelectric coefficient increased linearly with temperature. Dielectric loss also increases with temperature but remains within 0.2% of initial room temperature value. Change in dielectric properties and piezoelectric constant may be explained by depinning of domains or by domain wall motion. The piezoelectric material degradation was investigated microstructurally and crystallographically by using scanning electron microscope and x-ray diffraction method respectively. There were no noticeable changes in microstructure, crystal structure, unit cell dimension, or symmetry. The degraded PWAS material properties were determined by matching impedance and admittance spectrums from experimental results with a closed form circular PWAS analytical model. Analytical results showed that

  11. Effect of Nb Doping on High Temperature Oxidation Resistance of Ti-Al Alloyed Coatings

    Directory of Open Access Journals (Sweden)

    DAI Jing-jie

    2017-02-01

    Full Text Available Ti-Al alloyed coatings with different Nb doping contents were fabricated on TC4 titanium alloy by laser surface alloying to improve high temperature oxidation resistance of the alloy. Structures and high temperature oxidation behaviors of the alloyed coatings were analyzed and tested by X-ray diffraction (XRD, scanning electron microscope (SEM, energy dispersive spectrometer (EDS and box-type resistance furnace. The results show that the alloyed coatings consist of TiAl and Ti3Al, and no niobium compound are formed in Ti-Al-Nb alloyed coatings. The alloyed coatings are uniform and exhibit excellent metallurgical bonding with the substrates. A large amount of surface cracks and a few penetrating cracks are formed in Ti-Al alloyed coating without Nb doping, while no obvious cracks are formed in Ti-Al alloyed coating with Nb doping. The oxidation mass gains of all the alloyed coatings were significantly lower than those of the substrate. The alloyed coatings with Nb doping exhibit more excellent high temperature oxidation resistance due to the beneficial machanism of Nb doping. The mechanism of Nb doping on improving high temperature oxidation resistance of Ti-Al alloyed coatings includes reducing the defect concentration of TiO2, refining oxide grains and promoting the formation of Al2O3.

  12. Effect of Curing Temperature Histories on the Compressive Strength Development of High-Strength Concrete

    Directory of Open Access Journals (Sweden)

    Keun-Hyeok Yang

    2015-01-01

    Full Text Available This study examined the relative strength-maturity relationship of high-strength concrete (HSC specifically developed for nuclear facility structures while considering the economic efficiency and durability of the concrete. Two types of mixture proportions with water-to-binder ratios of 0.4 and 0.28 were tested under different temperature histories including (1 isothermal curing conditions of 5°C, 20°C, and 40°C and (2 terraced temperature histories of 20°C for an initial age of individual 1, 3, or 7 days and a constant temperature of 5°C for the subsequent ages. On the basis of the test results, the traditional maturity function of an equivalent age was modified to consider the offset maturity and the insignificance of subsequent curing temperature after an age of 3 days on later strength of concrete. To determine the key parameters in the maturity function, the setting behavior, apparent activation energy, and rate constant of the prepared mixtures were also measured. This study reveals that the compressive strength development of HSC cured at the reference temperature for an early age of 3 days is insignificantly affected by the subsequent curing temperature histories. The proposed maturity approach with the modified equivalent age accurately predicts the strength development of HSC.

  13. Effects of field high temperature on grain yield and quality of a subtropical type japonica rice—Pon-Lai rice

    Directory of Open Access Journals (Sweden)

    Yi-Chien Wu

    2016-01-01

    Full Text Available Typical japonica type rice is sensitive to high temperature. Pon-Lai rice is a special japonica type with adaptation to the subtropical climate in Taiwan. Facing climate change, rising temperatures would damage the yield and quality of rice production. This research was conducted using Pon-Lai rice in the field of a subtropical climate. We conducted 2 experiments, including a year-round experiment and collection of samples from different districts for building different temperature conditions. We analyzed the correlation between rising temperature and rice yield or quality. In our results, the critical period of temperature effect is 0–15 days after heading (H15. The threshold of high temperature damage in yield and appearance quality was 25–27 °C. Grain weight decreased about 2–6%, while the temperature of H15 was raised 1 °C above the thresholds. Perfect grain ratio and chalky grain ratio decreased and increased, respectively, while the temperature of H15 was raised above the thresholds. However, the high temperature in H15 affected the physicochemical characteristics. In addition, we found positive correlation between grain length to width ratio and perfect grain ratio. Grain length to width ratio could be an index of temperature effects for grain quality. In our study, when the temperature was below 30 °C, a rising temperature of H15 could damage rice yield and appearance quality, and change grain shape. Our results could provide reference for dealing with the warming future in other temperate rice-cultivated countries.

  14. Effect of gaseous ozone for control of stored product pests at low and high temperature

    DEFF Research Database (Denmark)

    Hansen, Lise Stengård; Hansen, Peer; Vagn Jensen, Karl-Martin

    2013-01-01

    Gaseous ozone (O3) has shown potential for control of insects in stored grain. A previous laboratory study determined doses of ozone necessary to control freely exposed and internal stages of eleven stored product pest species at 20 C. In this study the impact of temperature on the effect of ozon...

  15. Effects of WMA Additive on the Rheological Properties of Asphalt Binder and High Temperature Performance Grade

    Directory of Open Access Journals (Sweden)

    Jiupeng Zhang

    2015-01-01

    Full Text Available Sasobit additives with different dosages were added into 70# and 90# virgin asphalt binders to prepare WMA binders. The rheological properties, including G∗ and δ, were measured by using DSR at the temperature ranging from 46°C to 70°C, and the effects of temperature, additive dosage and aging on G∗/sin⁡δ, critical temperature, and H-T PG were investigated. The results indicate that WMA additive improves G∗ but reduces δ, and the improvement on 70# virgin binder is more significant. G∗/sin⁡δ exponentially decreases with the increasing temperature but linearly increases with the increasing additive dosage. Aging effect weakens the interaction between binder and additive but significantly increases the binder’s viscosity; that is why G∗/sin⁡δ is higher after short-term aging. In addition, the critical temperature increases with the increasing additive dosage, and the additive dosage should be more than 3% and 5% to improve H-T PG by one grade for 70# and 90# virgin binder, respectively.

  16. Coasting characteristic of the flywheel system under anisotropy effect of bulk high temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J.F., E-mail: wujf@ciomp.ac.cn; Li, Y.

    2014-10-15

    Highlights: • Coasting time was investigated from the point-view of HTS flywheel applications. • The coasting time of aligned growth section boundary pattern (AGSBP) is shorter than that of MGSBP. • The electric magnetic drag force with AGSBP is larger than that of MGSBP. • This result may also exist in the maglev guideline when the maglev train stops freely. - Abstract: High-temperature superconductors (HTSCs) array with aligned growth section boundary (GSB) pattern (AGSBP) exhibits larger levitation force and suppression of levitation force decay above a permanent magnet guideway (PMG) compared with misaligned GSB pattern (MGSBP) has been studied in maglev train application (Zheng et al., 2013). This result maybe helpful and support a new way for the HTS bearing design for flywheel systems. So, in this paper, we further examine this growth anisotropy effect on the maglev performance of flywheel system. Levitation force and coasting time were investigated from the point-view of HTS flywheel applications. The GS/GSB alignment of AGSBP bulk HTSCs produces larger levitation force than that of MGSBP, but the coasting time is shorter than that of MGSBP, that is to say, the electric magnetic drag force with AGSBP is larger than that of MGSBP. This result may also exist in the maglev guideline when the maglev train stops freely.

  17. HIGH TEMPERATURE VACUUM MIXER

    Directory of Open Access Journals (Sweden)

    E. D. Chertov

    2015-01-01

    Full Text Available The work is devoted to the creation of a new type of mixer to produce homogeneous mixtures of dissimilar materials applied to recycling of housing and communal services waste. The article describes the design of a dual-chamber device of the original high-temperature vacuum mixer, there investigated the processes occurring in the chambers of such devices. The results of theoretical and experimental research of the process of mixing recycled polyethylene with a mixture of "grinded food waste – Eco wool” are presented. The problem of the optimum choice of bending the curvilinear blades in the working volume of the seal, which is achieved by setting their profile in the form of involute arc of several circles of different radii, is examined . The dependences, allowing to define the limits of the changes of the main mode parameters the angular velocity of rotation of the working body of the mixer using two ways of setting the profile of the curvilinear blade mixer are obtained. Represented design of the mixer is proposed to use for a wide range of tasks associated with the mixing of the components with a strongly pronounced difference of physic al chemical properties and, in particular, in the production of composites out of housing and communal services waste.

  18. Numerical Simulation for Thermal Shock Resistance of Ultra-High Temperature Ceramics Considering the Effects of Initial Stress Field

    Directory of Open Access Journals (Sweden)

    Weiguo Li

    2011-01-01

    Full Text Available Taking the hafnium diboride ceramic as an example, the effects of heating rate, cooling rate, thermal shock initial temperature, and external constraint on the thermal shock resistance (TSR of ultra-high temperature ceramics (UHTCs were studied through numerical simulation in this paper. The results show that the external constraint has an approximately linear influence on the critical rupture temperature difference of UHTCs. The external constraint prepares a compressive stress field in the structure because of the predefined temperature field, and this compressive stress field relieves the tension stress in the structure when it is cooled down and then it improves the TSR of UHTCs. As the thermal shock initial temperature, a danger heating rate (or cooling rate exists where the critical temperature difference is the lowest.

  19. Effects of high temperatures on threatened estuarine fishes during periods of extreme drought.

    Science.gov (United States)

    Jeffries, Ken M; Connon, Richard E; Davis, Brittany E; Komoroske, Lisa M; Britton, Monica T; Sommer, Ted; Todgham, Anne E; Fangue, Nann A

    2016-06-01

    Climate change and associated increases in water temperatures may impact physiological performance in ectotherms and exacerbate endangered species declines. We used an integrative approach to assess the impact of elevated water temperature on two fishes of immediate conservation concern in a large estuary system, the threatened longfin smelt (Spirinchus thaleichthys) and endangered delta smelt (Hypomesus transpacificus). Abundances have reached record lows in California, USA, and these populations are at imminent risk of extirpation. California is currently impacted by a severe drought, resulting in high water temperatures, conditions that will become more common as a result of climate change. We exposed fish to environmentally relevant temperatures (14°C and 20°C) and used RNA sequencing to examine the transcriptome-wide responses to elevated water temperature in both species. Consistent with having a lower temperature tolerance, longfin smelt exhibited a pronounced cellular stress response, with an upregulation of heat shock proteins, after exposure to 20°C that was not observed in delta smelt. We detected an increase in metabolic rate in delta smelt at 20°C and increased expression of genes involved in metabolic processes and protein synthesis, patterns not observed in longfin smelt. Through examination of responses across multiple levels of biological organization, and by linking these responses to habitat distributions in the wild, we demonstrate that longfin smelt may be more susceptible than delta smelt to increases in temperatures, and they have little room to tolerate future warming in California. Understanding the species-specific physiological responses of sensitive species to environmental stressors is crucial for conservation efforts and managing aquatic systems globally. © 2016. Published by The Company of Biologists Ltd.

  20. The effect of bonding environment on iron isotope fractionation between minerals at high temperature

    Science.gov (United States)

    Sossi, Paolo A.; O'Neill, Hugh St. C.

    2017-01-01

    Central to understanding the processes that drive stable isotope fractionation in nature is their quantification under controlled experimental conditions. The polyvalent element iron, given its abundance in terrestrial rocks, exerts controls on the structural and chemical properties of minerals and melts. The iron isotope compositions of typical high temperature minerals are, however, poorly constrained and their dependence on intensive (e.g. fO2) and extensive (e.g. compositional) variables is unknown. In this work, experiments involving a reference phase, 2 M FeCl2·4H2O(l), together with an oxide mix corresponding to the bulk composition of the chosen mineral were performed in a piston cylinder in Ag capsules. The oxide mix crystallised in situ at 1073 K and 1 GPa, in equilibrium with the iron chloride, and was held for 72 h. In order to characterise the effect of co-ordination and oxidation state on the isotope composition independently, exclusively Fe2+ minerals were substituted in: VIII-fold almandine, VI-fold ilmenite, fayalite and IV-fold chromite and hercynite. Δ57FeMin-FeCl2 increases in the order VIII iron being the smaller, ferric ion. The composition of the VIFe2+-bearing minerals is similar to that of the aqueous FeCl2 fluid. To the degree that this represents the speciation of iron in fluids exsolving from magmas, the fractionation between them should be small, unless the iron is hosted in magnetite. By contrast, predominantly Fe2+-bearing mantle garnets should preserve a much lighter δ57Fe than their lower pressure spinel counterparts, a signature that may be reflected in partial melts from these lithologies. As the Fe-O bond lengths in fayalite and ilmenite are comparable, their isotope compositions overlap, suggesting that high Ti mare basalts acquired their heavy isotopic signature from ilmenite that crystallised late during lunar magma ocean solidification.

  1. Effect of stress and temperature on the micromechanics of creep in highly irradiated bone and dentin

    Energy Technology Data Exchange (ETDEWEB)

    Singhal, Anjali, E-mail: anjalisinghal2007@u.northwestern.edu [Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Deymier-Black, Alix C., E-mail: alixdeymier2010@u.northwestern.edu [Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Almer, Jonathan D., E-mail: almer@aps.anl.gov [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Dunand, David C., E-mail: dunand@northwestern.edu [Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States)

    2013-04-01

    Synchrotron X-ray diffraction is used to study in situ the evolution of phase strains during compressive creep deformation in bovine bone and dentin for a range of compressive stresses and irradiation rates, at ambient and body temperatures. In all cases, compressive strains in the collagen phase increase with increasing creep time (and concomitant irradiation), reflecting macroscopic deformation of the sample. By contrast, compressive elastic strains in the hydroxyapatite (HAP) phase, created upon initial application of compressive load on the sample, decrease with increasing time (and irradiation) for all conditions; this load shedding behavior is consistent with damage at the HAP–collagen interface due to the high irradiation doses (from ∼ 100 to ∼ 9,000 kGy). Both the HAP and fibril strain rates increase with applied compressive stress, temperature and irradiation rate, which is indicative of greater collagen molecular sliding at the HAP–collagen interface and greater intermolecular sliding (i.e., plastic deformation) within the collagen network. The temperature sensitivity confirms that testing at body temperature, rather than ambient temperature, is necessary to assess the in vivo behavior of bone and teeth. The characteristic pattern of HAP strain evolution with time differs quantitatively between bone and dentin, and may reflect their different structural organization. Highlights: ► First systematic study of varying creep stresses on bone and dentin at nanoscale. ► HAP in highly irradiated bone and dentin sheds load during creep at all stresses. ► This suggests HAP–collagen interfacial damage due to irradiation and applied stress. ► HAP and fibril strain rates increase with stress, temperature and irradiation. ► Temporal evolution of strains different in bone and dentin.

  2. Effects of temperature on stress corrosion cracking behavior of stainless steel and outer oxide distribution in cracks due to exposure to high-temperature water containing hydrogen peroxide

    Science.gov (United States)

    Nakano, Junichi; Sato, Tomonori; Kato, Chiaki; Yamamoto, Masahiro; Tsukada, Takashi; Kaji, Yoshiyuki

    2014-01-01

    Cracking growth tests were conducted in high-temperature water containing hydrogen peroxide (H2O2) at 561-423 K to evaluate the effects of H2O2 on stress corrosion cracking (SCC) of stainless steel (SS) at temperature lower than the boiling water reactor (BWR) operating temperature. Small compact tension (CT) specimens were prepared from thermally sensitized type 304 SS. Despite the observation of only a small portion intergranular SCC (IGSCC) near the side groove of the CT specimen at 561 K in high-temperature water containing 100 ppb H2O2, the IGSCC area expanded to the central region of the CT specimens at 423 and 453 K. Effects of H2O2 on SCC appeared intensely at temperature lower than the BWR operating temperature because of a reduction in the thermal decomposition of H2O2. To estimate the environment in the cracks, outer oxide distribution on the fracture surface and the fatigue pre-crack were examined by laser Raman spectroscopy and thermal equilibrium calculation was performed.

  3. The effect of high temperature on cause-specific mortality: A multi-county analysis in China.

    Science.gov (United States)

    Ban, Jie; Xu, Dandan; He, Mike Z; Sun, Qinghua; Chen, Chen; Wang, Wentao; Zhu, Pengfei; Li, Tiantian

    2017-09-01

    Although existing studies have linked high temperature to mortality in a small number of regions, less evidence is available on the variation in the associations between high temperature exposure and cause-specific mortality of multiple regions in China. Our study focused on the use of time series analysis to quantify the association between high temperature and different cause-specific mortalities for susceptible populations for 43 counties in China. Two-stage analyses adopting a distributed lag non-linear model (DLNM) and a meta-analysis allowed us to obtain county-specific estimates and national-scale pooled estimates of the nonlinear temperature-mortality relationship. We also considered different populations stratified by age and sex, causes of death, absolute and relative temperature patterns, and potential confounding from air pollutants. All of the observed cause-specific mortalities are significantly associated with higher temperature. The estimated effects of high temperature on mortality varied by spatial distribution and temperature patterns. Compared with the 90th percentile temperature, the overall relative risk (RR) at the 99th percentile temperature for non-accidental mortality is 1.105 (95%CI: 1.089, 1.122), for circulatory disease is 1.107 (95%CI: 1.081, 1.133), for respiratory disease is 1.095 (95%CI: 1.050, 1.142), for coronary heart disease is 1.073 (95%CI: 1.047, 1.099), for acute myocardial infarction is 1.072 (95%CI: 1.042, 1.104), and for stroke is 1.095 (95%CI: 1.052, 1.138). Based on our findings, we believe that heat-related health effect in China is a significant issue that requires more attention and allocation of existing resources. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Effects of high power ultrasonic vibration on temperature distribution of workpiece in dry creep feed up grinding.

    Science.gov (United States)

    Paknejad, Masih; Abdullah, Amir; Azarhoushang, Bahman

    2017-11-01

    Temperature history and distribution of steel workpiece (X20Cr13) was measured by a high tech infrared camera under ultrasonic assisted dry creep feed up grinding. For this purpose, a special experimental setup was designed and fabricated to vibrate only workpiece along two directions by a high power ultrasonic transducer. In this study, ultrasonic effects with respect to grinding parameters including depth of cut (a e ), feed speed (v w ), and cutting speed (v s ) has been investigated. The results indicate that the ultrasonic vibration has considerable effect on reduction of temperature, depth of thermal damage of workpiece and width of temperature contours. Maximum temperature reduction of 25.91% was reported at condition of v s =15m/s, v w =500mm/min, a e =0.4mm in the presence of ultrasonic vibration. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Advances in high temperature chemistry

    CERN Document Server

    Eyring, Leroy

    1969-01-01

    Advances in High Temperature Chemistry, Volume 2 covers the advances in the knowledge of the high temperature behavior of materials and the complex and unfamiliar characteristics of matter at high temperature. The book discusses the dissociation energies and free energy functions of gaseous monoxides; the matrix-isolation technique applied to high temperature molecules; and the main features, the techniques for the production, detection, and diagnosis, and the applications of molecular beams in high temperatures. The text also describes the chemical research in streaming thermal plasmas, as w

  6. Vaporization and configuration effects in a high-pressure/high-temperature combustor equipped with multiple Venturi-type fuel injectors

    Science.gov (United States)

    Locke, Randy J.; Chun, K. S.; Lee, C. M.; Ratvasky, William J.

    1994-03-01

    The flow field and fuel/air mixing patterns produced in an optically accessible, premixing/prevaporization section of a high pressure/high temperature combustor were examined via focused Schlieren high-speed photography. A focal plane, approximately 8 mm thick and centered within this section downstream of the fuel injectors, was imaged at a framing rate of 8,000 frames/second. High-speed focused Schlieren images were obtained for three different Venturi-type fuel injector configurations under identical experimental parameters. The results demonstrate the efficacy of this technique to discern fuel spray patternization, fuel-air mixing efficiencies, and mixing times of various fuel injector arrangements.

  7. "Thermal Stabilization Effect" of Al2O3 nano-dopants improves the high-temperature dielectric performance of polyimide.

    Science.gov (United States)

    Yang, Yang; He, Jinliang; Wu, Guangning; Hu, Jun

    2015-11-24

    Insulation performance of the dielectrics under extreme conditions always attracts widespread attention in electrical and electronic field. How to improve the high-temperature dielectric properties of insulation materials is one of the key issues in insulation system design of electrical devices. This paper studies the temperature-dependent corona resistance of polyimide (PI)/Al2O3 nanocomposite films under high-frequency square-wave pulse conditions. Extended corona resistant lifetime under high-temperature conditions is experimentally observed in the 2 wt% nanocomposite samples. The "thermal stabilization effect" is proposed to explain this phenomenon which attributes to a new kind of trap band caused by nanoparticles. This effect brings about superior space charge characteristics and corona resistance under high temperature with certain nano-doping concentration. The proposed theory is experimentally demonstrated by space charge analysis and thermally stimulated current (TSC) tests. This discovered effect is of profound significance on improving high-temperature dielectric properties of nanocomposites towards various applications.

  8. High-Temperature Spectroscopy of Organometallics: The Gol'danskii-Karyagin Effect in Ferrocene Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Herber, Rolfe H.; Nowik, Israel [Hebrew University, Racah Institute of Physics (Israel)

    2002-06-15

    The temperature dependence of the mean-square-amplitude of vibration and the motional anisotropy of the metal atom in a number of structurally related organometallics has been examined in detail and can be related to the molecular level architecture of these solids. In particular, it is noted that in octamethylferrocenylmethanol, there is a competition between the 'gear-wheel effect' observed in related octamethylferrocenyl complexes and hydrogen bonding between neighboring molecules in the solid below the melting point.

  9. Highly Sensitive Liquid Core Temperature Sensor Based on Multimode Interference Effects

    Directory of Open Access Journals (Sweden)

    Miguel A. Fuentes-Fuentes

    2015-10-01

    Full Text Available A novel fiber optic temperature sensor based on a liquid-core multimode interference device is demonstrated. The advantage of such structure is that the thermo-optic coefficient (TOC of the liquid is at least one order of magnitude larger than that of silica and this, combined with the fact that the TOC of silica and the liquid have opposite signs, provides a liquid-core multimode fiber (MMF highly sensitive to temperature. Since the refractive index of the liquid can be easily modified, this allows us to control the modal properties of the liquid-core MMF at will and the sensor sensitivity can be easily tuned by selecting the refractive index of the liquid in the core of the device. The maximum sensitivity measured in our experiments is 20 nm/°C in the low-temperature regime up to 60 °C. To the best of our knowledge, to date, this is the largest sensitivity reported for fiber-based MMI temperature sensors.

  10. Porosity Effect in the Core Thermal Hydraulics for Ultra High Temperature Gas-cooled Reactor

    Directory of Open Access Journals (Sweden)

    Motoo Fumizawa

    2008-12-01

    Full Text Available This study presents an experimental method of porosity evaluation and a predictive thermal-hydraulic analysis with packed spheres in a nuclear reactor core. The porosity experiments were carried out in both a fully shaken state with the closest possible packing and in a state of non-vibration. The predictive analysis considering the fixed porosity value was applied as a design condition for an Ultra High Temperature Reactor Experiment (UHTREX. The thermal-hydraulic computer code was developed and identified as PEBTEMP. The highest outlet coolant temperature of 1316 oC was achieved in the case of an UHTREX at Los Alamos Scientific Laboratory, which was a small scale UHTR. In the present study, the fuel was changed to a pebble type, a porous media. In order to compare the present pebble bed reactor and UHTREX, a calculation based on HTGR-GT300 was carried out in similar conditions with UHTREX; in other words, with an inlet coolant temperature of 871oC, system pressure of 3.45 MPa and power density of 1.3 w/cm3. As a result, the fuel temperature in the present pebble bed reactor showed an extremely lower value compared to that of UHTREX.

  11. Effect of Au nano-particles doping on polycrystalline YBCO high temperature superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Dadras, Sedigheh, E-mail: dadras@alzahra.ac.ir; Gharehgazloo, Zahra

    2016-07-01

    In this research, we prepared different Au nanoparticles (0.1–2 wt%) doped YBCO high temperature superconductor samples by sol-gel method. To characterize the samples, we used X-Ray diffraction (XRD) and scanning electron microscope (SEM) analysis. Results show the formation of orthorhombic phase of superconductivity for all prepared samples. We observed that by adding Au nanoparticles, the grains' size of the samples reduces from 76 nm to 47 nm as well. The critical current density (J{sub c}) and transition temperature (T{sub c}) were determined using current versus voltage (I–V) and resistivity versus temperature (ρ-T) measurements, respectively. We found that by increasing Au nanoparticles in the compound, in comparison to the pure YBCO sample, the transition temperature, pinning energy and critical current density will increase. Also, the highest J{sub c} is for 1 wt% Au doped YBCO compound that its critical current density is about 8 times more than the J{sub c} of pure one in 0.7 T magnetic field.

  12. Effect of Process Temperature on Virus Inactivation during High Hydrostatic Pressure Processing of Contaminated Fruit Puree and Juice.

    Science.gov (United States)

    Pan, Hao; Buenconsejo, Matthew; Reineke, Karl F; Shieh, Y Carol

    2016-09-01

    High pressure processing (HPP) can inactivate pathogens and retain fruit qualities. Elevated HPP pressure or time increases virus inactivation, but the effect of temperature is not consistently observed for norovirus and hepatitis A virus. In the present study, the effectiveness of HPP holding temperatures (puree using a 24-liter HPP system. The holding temperature was established by setting the HPP initial temperature via pretrials. All trials were able to arrive at the designated holding pressure and holding temperature simultaneously. MNV inactivation in juices was conducted at 300 MPa for 3 min with various holding temperatures (10 to 30°C). A regression equation was derived, Y = -0.08 × X + 2.6 log PFU, R2 = 0.96, where Y is the log reduction and X is the holding temperature. The equation was used to predict a 2.6-log reduction in juices at 0°C holding temperature and indicated that MNV inactivation was inversely proportional to temperature increase. MNV survival during HPP did not differ significantly in pomegranate and strawberry juices. However, MS2 coliphage inactivation was greater as the holding temperature increased (from 15 to 38°C) at 600 MPa for 3 min. The increased inactivation trend is presumably similar to that for hepatitis A virus, but the holding temperature was not correlated with the reduction of HPP-resistant MS2 in strawberry puree. When the HPP holding pressure was evaluated independently in strawberry puree, a 5-log reduction of MNV was predicted through regression analysis at the holding pressure of 424 MPa for 3 min at 20°C. These parameters should inactivate >5 log PFU of MNV in juices, based upon a greater inactivation in berry juice than in puree (1.16-versus 0.74-log reduction at 300 MPa). This research illustrates use of predictive inactivation and a feasible means for manipulating HPP parameters for effective virus inactivation in fruit juices and puree.

  13. Effect of High Temperature on Mineralogy, Microstructure, Shear Stiffness and Tensile Strength of Two Australian Mudstones

    Science.gov (United States)

    Liu, Xianfeng; Zhang, Chonglei; Yuan, Shengyang; Fityus, Stephen; Sloan, Scott William; Buzzi, Olivier

    2016-09-01

    This study aims at providing quality experimental data on the effects of temperature on tensile strength and small strain shear stiffness of two Australian mudstones. The objective is to provide multiscale data in view of developing a numerical model that can capture and simulate the complex multiphysics of underground coal fire propagation. Two mudstones were collected in the Hunter Valley, close to a known underground coal fire, referred to as "Burning Mountain." The rock specimens were heated to a range of temperatures (maximum of 900 °C) for 24 h, and the materials were comprehensively characterized by X-ray diffraction, thermal gravimetric analyses, optical microscopy and scanning electron microscopy. In addition, mercury intrusion porosimetry was used in order to track changes in pore size distribution with temperature. Investigations at microscale were complemented by testing at the macroscale. In particular, the paper focuses on the evolution of the tensile strength and small strain shear stiffness as the materials are subjected to heating treatment. Results show that both parameters evolve in a non-monotonic manner with temperature. The observed mechanical responses are fully explained and corroborated by microstructural observations.

  14. Effect of fuel burnup and cross sections on modular HTGR (High-Temperature Gas-cooled Reactor) reactivity coefficients

    Science.gov (United States)

    Lefler, W.; Baxter, A.; Mathews, D.

    1987-12-01

    The temperature dependence of the reactivity coefficient in a prismatic block Modular High-Temperature Gas-Cooled Reactor (MHTGR) design is examined and found to be large and negative. Temperature coefficient results obtained with the ENDF/B-V data library were almost the same as results obtained with the earlier versions of the ENDF/B data library usually used at GA Technologies Inc., in spite of a significant eigenvalue increase with the ENDF/B-V data. The effects of fuel burnup and arbitrarily assumed cross section variations were examined and tabulated.

  15. Effect of Temperature on the Galvanic Corrosion of Cu-Ni Alloy/High Strength Steel in Seawater

    Directory of Open Access Journals (Sweden)

    Wang Chun Li

    2016-01-01

    Full Text Available The galvanic corrosion behavior of Cu-Ni Alloy(B10/high strength steel (921A has been studied using a zero-resistance ammeter (ZRA in seawater at different temperatures. As well as it was systemically investigated by weight loss measurements, electrochemical methods and scanning electron microscope.Results showed 921A acts as the anode and B10 act as the cathodes. The effect of temperature on the galvanic corrosion is important, the corrosion rate became higher with the temperature increased.

  16. High-Temperature Piezoelectric Sensing

    Directory of Open Access Journals (Sweden)

    Xiaoning Jiang

    2013-12-01

    Full Text Available Piezoelectric sensing is of increasing interest for high-temperature applications in aerospace, automotive, power plants and material processing due to its low cost, compact sensor size and simple signal conditioning, in comparison with other high-temperature sensing techniques. This paper presented an overview of high-temperature piezoelectric sensing techniques. Firstly, different types of high-temperature piezoelectric single crystals, electrode materials, and their pros and cons are discussed. Secondly, recent work on high-temperature piezoelectric sensors including accelerometer, surface acoustic wave sensor, ultrasound transducer, acoustic emission sensor, gas sensor, and pressure sensor for temperatures up to 1,250 °C were reviewed. Finally, discussions of existing challenges and future work for high-temperature piezoelectric sensing are presented.

  17. High temperature superconductor accelerator magnets

    NARCIS (Netherlands)

    van Nugteren, J.

    2016-01-01

    For future particle accelerators bending dipoles are considered with magnetic fields exceeding 20T. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and

  18. The effect of high-level waste glass composition on spinel liquidus temperature

    Energy Technology Data Exchange (ETDEWEB)

    Hrma, Pavel R.; Riley, Brian J.; Crum, Jarrod V.; Matyas, Josef

    2014-01-15

    Spinel crystals precipitate in high-level waste glasses containing Fe, Cr, Ni , Mn, Zn, and Ru. The liquidus temperature (TL) of spinel as the primary crystallization phase is a function of glass composition and the spinel solubility (c0) is a function of both glass composition and temperature (T). Previously reported models of TL as a function of composition are based on TL measured directly, which requires laborious experimental procedures. Viewing the curve of c0 versus T as the liquidus line allows a significant broadening of the composition region for model fitting. This paper estimates TL as a function of composition based on c0 data obtained with the X-ray diffraction technique.

  19. The effect of high-level waste glass composition on spinel liquidus temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kruger, A. A. [Department of Energy, Office of River Protection, Richland, Washington (United States); Riley, Brian J. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Crum, Jarrod V. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Hrma, Pavel [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Matyas, Josef [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

    2012-11-15

    Spinel crystals precipitate in high-level waste glasses containing Fe, Cr, Ni, Mn, Zn, and Ru. The liquidus temperature (T{sub L}d) of spinel as the primary crystallization phase is a function of glass composition, and the spinel solubility (c{sub o}) is a function of both glass composition and temperature (T). Previously reported models of T{sub L} as a function of composition are based on T{sub L} measured directly, which requires laborious experimental procedures. Viewing the curve of c{sub o} versus T as the liquidus line allows a significant broadening of the composition region for model fitting. This paper estimates T{sub L} as a function of composition based on c{sub o} data obtained with the X-ray diffraction technique.

  20. Life at High Temperatures

    Indian Academy of Sciences (India)

    2005-09-15

    Sep 15, 2005 ... or more in the vicinity of geothermal vents in the deep sea and the plant Tidestromia oblongifolia (Amaranthaceae) found in Death. Valley in California, where the hottest temperature on earth ever recorded during 43 consecutive days in 1917 was >48 °C. (Guinness Book of W orId Records, 1999).

  1. Effectiveness of high temperature innovative geometry fixed ceramic matrix regenerators used in glass furnaces

    Directory of Open Access Journals (Sweden)

    Wołkowycki Grzegorz

    2016-03-01

    Full Text Available The paper presents the effectiveness of waste heat recovery regenerators equipped with innovative ceramic matrix forming an integral part of a real glass furnace. The paper full description of the regenerators’ matrix structure with its dimensions, thermo-physical properties and operating parameters is included experimentally determined was the effectiveness of the regenerators has been descrbed using the obtained experimental data such as the operating temperature, gas flows as well as the gases generated during the liquid glass manufacturing process. The effectiveness values refer not only to the heating cycle when the regenerator matrix is heated by combustion gases but also to the cooling cycle in which the matrix is cooled as a result of changes in the direction of the flowing gas. On the basis of the determined effectiveness values for both cycles and measurement uncertainties it was possible, to calculate the weighted average efficiency for each of the regenerators.

  2. Effect of High Pressure and Temperature on Structural, Thermodynamic and Thermoelectric Properties of Quaternary CoFeCrAl Alloy

    Science.gov (United States)

    Bhat, Tahir Mohiuddin; Gupta, Dinesh C.

    2017-12-01

    Employing first-principles based on density functional theory we have investigated the structural, magneto-electronic, thermoelectric and thermodynamic properties of quaternary Heusler alloy CoFeCrAl. Electronic band structure displays that CoFeCrAl is an indirect band gap semiconductor in spin-down state with the band gap value of 0.65 eV. Elastic constants reveal CoFeCrAl is a mechanically stable structure having a Debye temperature of 648 K along with a high melting temperature (2130 K). The thermoelectric properties in the temperature range 50-800 K have been calculated. CoFeCrAl possesses a high Seebeck coefficient of - 46 μV/K at room temperature along with the huge power factor of ˜ 4.8 (1012 μW cm-1 K-2 s-1) which maximizes the figure-of-merit up to ˜ 0.75 at 800 K temperature and suggesting CoFeCrAl as potential thermoelectric material. The effect of high pressure and high temperature on the thermal expansion, Grüneisen parameter and heat capacity were also studied by using the quasi-harmonic Debye model.

  3. Effects of Biomass Feedstock on the Yield and Reactivity of Soot from Fast Pyrolysis at High Temperatures

    DEFF Research Database (Denmark)

    Trubetskaya, Anna; Jensen, Peter A.; Glarborg, Peter

    This study investigated the effect of feedstock on the yield, nanostructure and reactivity of soot. Woody and herbaceous biomass were pyrolyzed at high heating rates and temperatures of 1250 and 1400°C in a drop tube furnace. The collected solid residues were structurally characterized by electron...

  4. Effects of High Temperature and Water Stress on Seed Germination of the Invasive Species Mexican Sunflower.

    Science.gov (United States)

    Wen, Bin

    2015-01-01

    Mexican sunflower is native to Mexico and Central America and was introduced into China early last century. Now it has widely naturalized and is exhibiting increasing invasiveness in South China. As this species often dominates bare ground, a habitat characterized by extreme fluctuation in temperature and water, it is reasonable to hypothesize that it has special adaptations to high temperature and water stress. Using laboratory experiments to simulate these stresses, this study investigated the response of Mexican sunflower seed germination to temperature and water stress, and compared these responses with those previously reported for another invasive, bamboo piper, which is confined to relatively cool and moist habitats in Xishuangbanna. As expected, Mexican sunflower seeds exhibited higher tolerance to these stresses than bamboo piper. Germination of Mexican sunflower seeds was highest at 15-30°C, but significant numbers of seeds germinated and formed seedlings at 10°C and 35°C, at which no bamboo piper seeds formed seedlings, indicating a wider temperature range for germination than the latter. Roughly half the seeds survived 240 h continuous heat treatment and up to 15 h daily periodical heat treatment at 40°C, while bamboo piper seeds were mostly killed by these treatments. About 20% of Mexican sunflower but no bamboo piper seeds germinated after heat treatment for 30 min at 80°C. Germination was completely inhibited in bamboo piper seeds at -0.6 mPa, while 20-60% of Mexican sunflower seeds germinated depending on PEG or NaCl as osmoticum. This higher tolerance in Mexican sunflower seeds accords with its stronger invasiveness in this area. This comparison between two plant invaders demonstrates that invasiveness is not an all-or-nothing situation, and that adaptation to local habitats is a critical determinant of successful invasiveness for an alien plant.

  5. High temperature solution-nitriding and low-temperature nitriding of AISI 316: Effect on pitting potential and crevice corrosion performance

    DEFF Research Database (Denmark)

    Bottoli, Federico; Jellesen, Morten Stendahl; Christiansen, Thomas Lundin

    2018-01-01

    Stainless steels grade AISI 316 was subjected to high temperature solution nitriding and low-temperature nitriding in order to dissolve various amounts of nitrogen in the bulk (up to approx. 0.45wt%) and in a surface layer (up to approx. 13wt%), respectively. Potentiodynamic polarization tests in...... at the material surface through low-temperature nitriding resulted in a considerable improvement of the pitting potential and the crevice corrosion performance of the steels.......Stainless steels grade AISI 316 was subjected to high temperature solution nitriding and low-temperature nitriding in order to dissolve various amounts of nitrogen in the bulk (up to approx. 0.45wt%) and in a surface layer (up to approx. 13wt%), respectively. Potentiodynamic polarization tests...... in a 0.1M NaCl solution and crevice corrosion immersion tests in 3wt% FeCl3 solution were studied before and after the bulk and surface treatments.Nitrogen addition in the bulk proved to have a beneficial effect on the pitting resistance of the alloy. The formation of a zone of expanded austenite...

  6. Effect of Fast Pyrolysis Conditions on Structural Transformation and Reactivity of Herbaceous Biomasses at High Temperatures

    DEFF Research Database (Denmark)

    Trubetskaya, Anna; Jensen, Anker D.; Jensen, Peter Arendt

    and formation silanol silicons at higher temperatures. The microscopy and 2D imaging analysis show that the differences in ash and extractives of rice husks and wheat straw affect significantly the char particle size and shape. The char yields of rice husks in the EFR, correspond to the WMR results, emphasizing...... and particle size on the char yield. X-ray diffractometry (XRD), N-adsorption (BET), scanning electron microscopy (SEM), particle size analysis (CAMSIZER XT), nuclear magnetic resonance spectroscopy (29Si NMR; 13C NMR) and electron spinning resonance spectroscopy (ESR) were conducted to investigate the effect...

  7. Effects of sample storage time, temperature and syringe type on blood gas tensions in samples with high oxygen partial pressures.

    OpenAIRE

    Pretto, J. J.; Rochford, P D

    1994-01-01

    BACKGROUND--Although plastic arterial sampling syringes are now commonly used, the effects of sample storage time and temperature on blood gas tensions are poorly described for samples with a high oxygen partial pressure (PaO2) taken with these high density polypropylene syringes. METHODS--Two ml samples of tonometered whole blood (PaO2 86.7 kPa, PaCO2 4.27 kPa) were placed in glass syringes and in three brands of plastic blood gas syringes. The syringes were placed either at room temperature...

  8. [Effects of drought stress, high temperature and elevated CO2 concentration on the growth of winter wheat].

    Science.gov (United States)

    Si, Fu-Yan; Qiao, Yun-Zhou; Jiang, Jing-Wei; Dong, Bao-Di; Shi, Chang-Hai; Liu, Meng-Yu

    2014-09-01

    The impacts of climate change on the grain yield, photosynthesis, and water conditions of winter wheat were assessed based on an experiment, in which wheat plants were subjected to ambient and elevated CO2 concentrations, ambient and elevated temperatures, and low and high water conditions independently and in combination. The CO2 enrichment alone had no effect on the photosynthesis of winter wheat, whereas higher temperature and drought significantly decreased the photosynthetic rate. Water conditions in flag leaves were not significantly changed at the elevated CO2 concentration or elevated temperature. However, drought stress decreased the relative water content in flag leaves, and the combination of elevated temperature and drought reduced the water potential in flag leaves. The combination of elevated CO2 concentration, elevated temperature, and drought significantly reduced the photosynthetic rate and water conditions, and led to a 41.4% decrease in grain yield. The elevated CO2 concentration alone increased the grain yield by 21.2%, whereas the elevated temperature decreased the grain yield by 12.3%. The grain yield was not affected by the combination of elevated CO2 concentration and temperature, but the grain yield was significantly decreased by the drought stress if combined with any of the climate scenarios applied in this study. These findings suggested that maintaining high soil water content might be a vital means of reducing the potential harm caused by the climate change.

  9. High temperature materials; Materiaux a hautes temperatures

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    The aim of this workshop is to share the needs of high temperature and nuclear fuel materials for future nuclear systems, to take stock of the status of researches in this domain and to propose some cooperation works between the different research organisations. The future nuclear systems are the very high temperature (850 to 1200 deg. C) gas cooled reactors (GCR) and the molten salt reactors (MSR). These systems include not only the reactor but also the fabrication and reprocessing of the spent fuel. This document brings together the transparencies of 13 communications among the 25 given at the workshop: 1) characteristics and needs of future systems: specifications, materials and fuel needs for fast spectrum GCR and very high temperature GCR; 2) high temperature materials out of neutron flux: thermal barriers: materials, resistance, lifetimes; nickel-base metal alloys: status of knowledge, mechanical behaviour, possible applications; corrosion linked with the gas coolant: knowledge and problems to be solved; super-alloys for turbines: alloys for blades and discs; corrosion linked with MSR: knowledge and problems to be solved; 3) materials for reactor core structure: nuclear graphite and carbon; fuel assembly structure materials of the GCR with fast neutron spectrum: status of knowledge and ceramics and cermets needs; silicon carbide as fuel confinement material, study of irradiation induced defects; migration of fission products, I and Cs in SiC; 4) materials for hydrogen production: status of the knowledge and needs for the thermochemical cycle; 5) technologies: GCR components and the associated material needs: compact exchangers, pumps, turbines; MSR components: valves, exchangers, pumps. (J.S.)

  10. Effects of high temperature on photosynthesis and related gene expression in poplar

    Science.gov (United States)

    2014-01-01

    Background High temperature, whether transitory or constant, causes physiological, biochemical and molecular changes that adversely affect tree growth and productivity by reducing photosynthesis. To elucidate the photosynthetic adaption response and examine the recovery capacity of trees under heat stress, we measured gas exchange, chlorophyll fluorescence, electron transport, water use efficiency, and reactive oxygen-producing enzyme activities in heat-stressed plants. Results We found that photosynthesis could completely recover after less than six hours of high temperature treatment, which might be a turning point in the photosynthetic response to heat stress. Genome-wide gene expression analysis at six hours of heat stress identified 29,896 differentially expressed genes (15,670 up-regulated and 14,226 down-regulated), including multiple classes of transcription factors. These interact with each other and regulate the expression of photosynthesis-related genes in response to heat stress, controlling carbon fixation and changes in stomatal conductance. Heat stress of more than twelve hours caused reduced electron transport, damaged photosystems, activated the glycolate pathway and caused H2O2 production; as a result, photosynthetic capacity did not recover completely. Conclusions This study provides a systematic physiological and global gene expression profile of the poplar photosynthetic response to heat stress and identifies the main limitations and threshold of photosynthesis under heat stress. It will expand our understanding of plant thermostability and provides a robust dataset for future studies. PMID:24774695

  11. High Temperature Superconductor Machine Prototype

    DEFF Research Database (Denmark)

    Mijatovic, Nenad; Jensen, Bogi Bech; Træholt, Chresten

    2011-01-01

    A versatile testing platform for a High Temperature Superconductor (HTS) machine has been constructed. The stationary HTS field winding can carry up to 10 coils and it is operated at a temperature of 77K. The rotating armature is at room temperature. Test results and performance for the HTS field...

  12. Effects of Stoichiometry on Transformation Temperatures and Actuator-Type Performance of NiTiPd and NiTiPdX High-Temperature Shape Memory Alloys

    Science.gov (United States)

    Bigelow, Glen S.; Gaydosh, Darrell; Garg, Anita; Padula, Santo A., II; Noebe, Ronald D.

    2007-01-01

    High-temperature shape memory NiTiPd and NiTiPdX (X=Au, Pt, Hf) alloys were produced with titanium equivalent (Ti+Hf) compositions of 50.5, 50.0, 49.5, and 49.0 at.%. Thermo-mechanical testing in compression was used to evaluate the transformation temperatures, transformation strain, work output, and permanent deformation behavior of each alloy to study the effects of quaternary alloying and stoichiometry on high-temperature shape memory alloy behavior. Microstructural evaluation showed the presence of second phases for all alloy compositions. No load transformation temperatures in the stoichiometric alloys were relatively unchanged by Au and Pt substitutions, while the substitution of Hf for Ti causes a drop in transformation temperatures. The NiTiPd, NiTiPdAu and NiTiPdHf alloys exhibited transformation temperatures that were highest in the Ti-rich compositions, slightly lower at stoichiometry, and significantly reduced when the Ti equivalent composition was less than 50 at.%. For the NiTiPdPt alloy, transformation temperatures were highest for the Ti-rich compositions, lowest at stoichiometry, and slightly higher in the Ni-rich composition. When thermally cycled under constant stresses of up to 300 MPa, all of the alloys had transformation strains, and therefore work outputs, which increased with increasing stress. In each series of alloys, the transformation strain and thus work output was highest for stoichiometric or Ti-rich compositions while permanent strain associated with the constant-load thermal cycling was lowest for alloys with Ni-equivalent-rich compositions. Based on these results, basic rules for optimizing the composition of NiTiPd alloys for actuator performance will be discussed.

  13. Magnetic Effects in a Moderate-Temperature, High-Beta, Toroidal Plasma Device

    Science.gov (United States)

    Edwards, W. F.; Singh, A. K.; Held, E. D.

    2011-10-01

    A small toroidal machine (STOR-1M; minor radius 4.5 cm), on loan from the University of Saskatchewan, has been modified to operate at hydrogen ionization levels ~0.1%, beta values between 0.1 and 1, electron number density ~5x1016/m3, temperature ~5 eV, and applied toroidal magnetic field ~20 gauss. Plasma is generated using magnetron-produced microwaves. Langmuir and Hall probes determine radial profiles of electron number density, temperature, and magnetic field. For most values of the externally-applied magnetic field, the internal field is the same with or without plasma, however, in a narrow window of B, diamagnetism and other effects are present. The effect is observed with no externally induced current; plasma currents are self generated through some sort of relaxation process. Beta and radius conditions correlate well with similar magnetic structures in the laboratory (eg., plasma focus, Z pinch) and in space (eg., Venus flux ropes, solar coronal loops).

  14. AC Losses and Their Thermal Effect in High-Temperature Superconducting Machines

    DEFF Research Database (Denmark)

    Song, Xiaowei (Andy); Mijatovic, Nenad; Zou, Shengnan

    2016-01-01

    In transient operations or fault conditions, hightemperature superconducting (HTS) machines suffer ac losses, which have an influence on the thermal stability of superconducting windings. In this paper, a method to calculate ac losses and their thermal effect in HTS machines is presented....... The method consists of three submodels that are coupled only in one direction. The magnetic field distribution is first solved in a machine model, assuming a uniform current distribution in HTS windings. The magnetic fields on the boundaries are then used as inputs for an ac loss model that has a homogeneous...... approximation and solves the H formulation. Afterward, the computed ac losses are considered as the heat source in a thermal model to study the temperature profile in HTS windings. The method proposed is able to evaluate ac losses and their thermal effect, thus providing a reference to design an HTS machine...

  15. High temperature autoclave vacuum seals

    Science.gov (United States)

    Hoffman, J. R.; Simpson, W. G.; Walker, H. M.

    1971-01-01

    Aluminum sheet forms effective sealing film at temperatures up to 728 K. Soft aluminum wire rings provide positive seal between foil and platen. For applications at temperatures above aluminum's service temperature, stainless steel is used as film material and copper wire as sealant.

  16. Effect of sintering time and temperature on properties of high pressure assisted WC/Co hard metal composite

    Energy Technology Data Exchange (ETDEWEB)

    Karimi, M.M.; Gomes, U.U.; Oliveira, M.P.; Filgueira, M. [Universidade Federal do Rio Grande do Norte (UFRN), RN (Brazil)

    2016-07-01

    Full text: WC/Co is widely used as cutting tools, because has a unique combination of high strength, hardness, toughness, and moderate stiffness, especially with fine grained WC and finely distributed cobalt. WC/Co powder mixture sinters by different methods such as vacuum sintering, microwave sintering and SPS. High pressure high temperature (HPHT) sintering is a proposed method that can results in better distribution of cobalt and avoid undesirable phases by using high pressure, high temperature and very low sintering time. In this study, a powder mixture of WC- 10 wt% Co was sintered by HPHT at 1500 to 1900 deg C under a pressure of 7.7 GPa for 2 and 3 minutes. Microstructural/structural analyses were performed by SEM/EDS and XRD. Hardness was also done to obtain the effect of sintering parameters. It was found that increasing sintering time in HPHT sintering method at a constant temperature can improve properties of WC/Co hard metal. It was also realized that both sintering temperature and time have effect on hardness and density. (author)

  17. Effect of annealing temperature and time on microstructure and mechanical properties of high Cr ferritic casting steel

    Science.gov (United States)

    Suo, Z. Y.; Fu, L. M.; Zhang, R. N.; Wang, Y. J.; Shan, A. D.

    2017-09-01

    A new-type of high Cr ferrite cast steel was designed and investigated. Effects of annealing temperature and time on the microstructure and mechanical properties of the high Cr ferrite cast steel were studied. The results show that the microstructures of the as-cast and annealing steels are composed of ferrite and (Cr•Fe)23C6 carbide. The morphology of carbides is from long rod and the continuous network to crystal precipitation for the steels with increasing of annealing temperature and time. The impact toughness is slightly increased from 6 J/cm2 to 8 J/cm2 when the annealing temperature increases from 1180 ℃ to 1200 ℃. But the hardness is about HB 200 and no obvious differences between the as-cast and annealing steels. The most suitable annealing temperature and time are 1200 ℃ and 5 h, respectively. The wear resistance of the high Cr ferrite cast steel is increased and improved with annealing temperature and holding time at 260 ℃. The wear mechanism is changed from abrasion wear to abrasive and adhesive wear. The good wear-resistant of the high Cr ferrite cast steel is mainly attributed to the fine uniformly dispersed carbides.

  18. Effect of treatment temperature on collagen structures of the decellularized carotid artery using high hydrostatic pressure.

    Science.gov (United States)

    Negishi, Jun; Funamoto, Seiichi; Kimura, Tsuyoshi; Nam, Kwangoo; Higami, Tetsuya; Kishida, Akio

    2011-09-01

    Decellularized tissues have attracted a great deal of attention as regenerating transplantation materials. A decellularizing method based on high hydrostatic pressure (HHP) has been developed, and the preparation of many types of decellularized tissues has been investigated, including aorta, cornea, and dermis. The preparation of a small-diameter vascular graft was studied using a carotid artery from the viewpoint of collagen denaturation and leakage. After HHP, the carotid artery was washed at two washing temperatures (37 and 4°C). Histological evaluation, collagen content measurement and circular dichroism (CD) measurement indicated that the washing temperatures clearly affected the collagen structure of the decellularized carotid artery. The amount of collagen decreased in the carotid artery decellularized by HHP washed at 37°C (HHP/37°C). On the other hand, the amount and structure of collagen were preserved in the carotid artery washed at 4°C after HHP (HHP/4°C). In rat carotid artery syngeneic transplantation, the HHP/37°C decellularized carotid artery occluded after 2 weeks, but the HHP/4°C decellularized one did not. These results indicate that collagen denaturation and leakage of the decellularized carotid artery affect the in vivo performance of the carotid artery.

  19. Effects of transient high temperature treatment on the intestinal flora of the silkworm Bombyx mori.

    Science.gov (United States)

    Sun, Zhenli; Kumar, Dhiraj; Cao, Guangli; Zhu, Liyuan; Liu, Bo; Zhu, Min; Liang, Zi; Kuang, Sulan; Chen, Fei; Feng, Yongjie; Hu, Xiaolong; Xue, Renyu; Gong, Chengliang

    2017-06-13

    The silkworm Bombyx mori is a poikilotherm and is therefore sensitive to various climatic conditions. The influence of temperature on the intestinal flora and the relationship between the intestinal flora and gene expression in the silkworm remain unknown. In the present study, changes of the intestinal flora at 48, 96 and 144 h following transient high temperature treatment (THTT) of 37 °C for 8 h were investigated. According to principal component analysis, the abundances of Enterococcus and Staphylococcus showed a negative correlation with other dominant genera. After THTT, the gene expression levels of spatzle-1 and dicer-2 were increased and decreased, respectively, which suggested that the Toll and RNAi pathways were activated and suppressed, respectively. The species-gene expression matrix confirmed that the spatzle-1 and dicer-2 gene expression levels were negatively and positively correlated, respectively, with the abundance of Enterococcus and Staphylococcus in the control. The abundance of Variovorax post-THTT was positively correlated with the spatzle-1 gene expression level, whereas the community richness of Enterococcus was negatively correlated with the spatzle-1 gene expression level and positively correlated with the dicer-2. The results of the present investigation provide new evidence for understanding the relationships among THTT, intestinal flora and host gene expression.

  20. Temporal Variability in Vertical Groundwater Fluxes and the Effect of Solar Radiation on Streambed Temperatures Based on Vertical High Resolution Distributed Temperature Sensing

    Science.gov (United States)

    Sebok, E.; Karan, S.; Engesgaard, P. K.; Duque, C.

    2013-12-01

    Due to its large spatial and temporal variability, groundwater discharge to streams is difficult to quantify. Methods using vertical streambed temperature profiles to estimate vertical fluxes are often of coarse vertical spatial resolution and neglect to account for the natural heterogeneity in thermal conductivity of streambed sediments. Here we report on a field investigation in a stream, where air, stream water and streambed sediment temperatures were measured by Distributed Temperature Sensing (DTS) with high spatial resolution to; (i) detect spatial and temporal variability in groundwater discharge based on vertical streambed temperature profiles, (ii) study the thermal regime of streambed sediments exposed to different solar radiation influence, (iii) describe the effect of solar radiation on the measured streambed temperatures. The study was carried out at a field site located along Holtum stream, in Western Denmark. The 3 m wide stream has a sandy streambed with a cobbled armour layer, a mean discharge of 200 l/s and a mean depth of 0.3 m. Streambed temperatures were measured with a high-resolution DTS system (HR-DTS). By helically wrapping the fiber optic cable around two PVC pipes of 0.05 m and 0.075 m outer diameter over 1.5 m length, temperature measurements were recorded with 5.7 mm and 3.8 mm vertical spacing, respectively. The HR-DTS systems were installed 0.7 m deep in the streambed sediments, crossing both the sediment-water and the water-air interface, thus yielding high resolution water and air temperature data as well. One of the HR-DTS systems was installed in the open stream channel with only topographical shading, while the other HR-DTS system was placed 7 m upstream, under the canopy of a tree, thus representing the shaded conditions with reduced influence of solar radiation. Temperature measurements were taken with 30 min intervals between 16 April and 25 June 2013. The thermal conductivity of streambed sediments was calibrated in a 1D flow

  1. Effect of Conditioning Treatments on the Survival of Radopholus similis at High Temperatures.

    Science.gov (United States)

    Arcinas, A; Sipes, B S; Hara, A H; Tsang, M M C

    2005-09-01

    Heat treatments are an environmentally safe method for eliminating quarantine pests from tropical foliage. Conditioning heat treatments can induce thermotolerance against subsequent and otherwise phytotoxic temperatures in tropical foliage, allowing heat treatments to be even more effective. However, if thermotolerance is also induced in nematodes of quarantine significance like Radopholus similis, heat treatments would be rendered ineffective. A lethal thermal death point (LT(99.9)) was established for R. similis by recording mortality at 25 (control temperature), 43 degrees C, 45 degrees C, 47 degrees C, or 49 degrees C after a 0, 1-, 2-, 4-, 6-, 8-, 10-, 12-, or 15-minute exposure. In a second experiment, nematodes were conditioned at 35, 40, or 45 degrees C for 0, 15, 30, 60, 120, and 180 minutes, allowed to rest for 3 hours, and then challenged at 47 degrees C for 5 minutes. No nematodes survived the challenge heat treatment; rather, nematode mortality was hastened by the conditioning treatment itself. In a third experiment, R. similis inside anthurium roots were conditioned at 25 degrees C or 40 degrees C for 15 minutes and then treated at 45 degrees C for up to 8 minutes. Mortality of conditioned and unconditioned nematodes was similar (P > 0.1). Conditioning treatments increase plant thermotolerance but do not induce thermotolerance in R. similis. Heat treatments have promise as disinfection protocols for quarantines.

  2. Effects of atamp-charging coke making on strength and high temperature thermal properties of coke.

    Science.gov (United States)

    Zhang, Yaru; Bai, Jinfeng; Xu, Jun; Zhong, Xiangyun; Zhao, Zhenning; Liu, Hongchun

    2013-12-01

    The stamp-charging coke making process has some advantages of improving the operation environment, decreasing fugitive emission, higher gas collection efficiency as well as less environmental pollution. This article describes the different structure strength and high temperature thermal properties of 4 different types of coke manufactured using a conventional coking process and the stamp-charging coke making process. The 4 kinds of cokes were prepared from the mixture of five feed coals blended by the petrography blending method. The results showed that the structure strength indices of coke prepared using the stamp-charging coke method increase sharply. In contrast with conventional coking process, the stamp-charging process improved the coke strength after reaction but had little impact on the coke reactivity index. Copyright © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  3. High Temperature Electrostrictive Ceramics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes to develop high temperature electrostrictors from bismuth-based ferroelectrics. These materials will exhibit high strain and low loss in...

  4. Effects of prior surface damage on high-temperature oxidation of Fe-, Ni-, and Co-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Peter Julian [ORNL; Lowe, Tracie M [ORNL; Pint, Bruce A [ORNL

    2009-01-01

    Multi-component metallic alloys have been developed to withstand high-temperature service in corrosive environments. Some of these applications, like exhaust valve seats in internal combustion engines, must also resist sliding, impact, and abrasion. The conjoint effects of temperature, oxidation, and mechanical contact can result in accelerated wear and the formation of complex surface layers whose properties differ from those of the base metal and the oxide scale that forms in the absence of mechanical contact. The authors have investigated the effects of prior surface damage, produced by scratch tests, on the localized reformation of oxide layers. Three high-performance commercial alloys, based on iron, nickel, and cobalt, were used as model materials. Thermogravimetric analysis (TGA) was used to determine their static oxidation rates at elevated temperature (850o C). A micro-abrasion, ball-cratering technique was used to measure oxide layer thickness and to compare it with TGA results. By using taper-sectioning techniques and energy-dispersive elemental mapping, a comparison was made between oxide compositions grown on non-damaged surfaces and oxides that formed on grooves produced by a diamond stylus. Microindentation and scratch hardness data revealed the effects of high temperature exposure on both the substrate hardness and the nature of oxide scale disruption. There were significant differences in elemental distribution between statically-formed oxides and those that formed on scratched regions

  5. EFFECTS OF HEAT TREATMENTS ON MICROSTRUCTURES AND MECHANICAL PROPERTIES OF DUAL PHASE ODS STEELS FOR HIGH TEMPERATURE STRENGTH

    Directory of Open Access Journals (Sweden)

    SANGHOON NOH

    2013-11-01

    Full Text Available In the present study, the effects of various heat treatments on the microstructure and mechanical properties of dual phase ODS steels were investigated to enhance the high strength at elevated temperature. Dual phase ODS steels have been designed by the control of ferrite and austenite formers, i.e., Cr, W and Ni, C in Fe-based alloys. The ODS steels were fabricated by mechanical alloying and a hot isostatic pressing process. Heat treatments, including hot rolling-tempering and normalizing-tempering with air- and furnace-cooling, were carefully carried out. It was revealed that the grain size and oxide distributions of the ODS steels can be changed by heat treatment, which significantly affected the strengths at elevated temperature. Therefore, the high temperature strength of dual phase ODS steel can be enhanced by a proper heat treatment process with a good combination of ferrite grains, nano-oxide particles, and grain boundary sliding.

  6. High Temperature Surface Interactions

    Science.gov (United States)

    1989-11-01

    oxidation rate of "pure SiC* in air (from compilation of data by Schlichting6). For T < 14001C, partial cristobalite formation; T > 1400"C, decreased...aluminium content is high enough, the beta phase percolates and contains a dispersion of -- Ni particles. Such a tructure is certainly less favourable

  7. Effects of intermittent 60-Hz high voltage electric fields on metabolism, activity, and temperature in mice

    Energy Technology Data Exchange (ETDEWEB)

    Rosenbergy, R.S; Duffy, P.H.; Sacher, G.A.

    1981-01-01

    Transient effects of 100-kV/m extremely low frequency electric fields were studied in the white footed deermouse, Peromyscus leucopus. Gross motor activity, carbon dioxide production, oxygen consumption, and core body temperature were monitored before, during, and after intermittent field exposures (four hour-long exposures, at one-hour intervals). Thirty-four mice were exposed in cages with plastic floors floating above ground potential, and 21 mice were exposed in cages with grounded metal floor plates. The first field exposure produced an immediate, transient increase of activity and gas measures during the inactive phase of the circadian cycle. All measures returned to baseline levels before the second exposure and were not significantly changed throughout the remainder of the exposures. The rapid habituation of field-induced arousal suggests that significant metabolic changes will not be measured in experiments in which the interval between exposure and measurement is greater than two hours.

  8. Phase Transformation and Shape Memory Effect of Ti-Pd-Pt-Zr High-Temperature Shape Memory Alloys

    Science.gov (United States)

    Yamabe-Mitarai, Yoko; Takebe, Wataru; Shimojo, Masayuki

    2017-11-01

    To understand the potential of high-temperature shape memory alloys, we have investigated the phase transformation and shape memory effect of Ti-(50 - x)Pt-xPd-5Zr alloys (x = 0, 5, and 15 at.%), which present the B2 structure in the austenite phase and B19 structure in the martensite phase. Their phase transformation temperatures are very high; A f and M f of Ti-50Pt are 1066 and 1012 °C, respectively. By adding Zr and Pd, the phase transition temperatures decrease, ranging between 804 and 994 °C for A f and 590 and 865 °C for M f. Even at the high phase transformation temperature, a maximum recovery ratio of 70% was obtained for one cycle in a thermal cyclic test. A work output of 1.2 J/cm3 was also obtained. The recovery ratio obtained by the thermal cyclic test was less than 70% because the recovery strain was < 1% and a large irrecoverable strain was obtained. The shape recovery was explained by the austenite strength. The training effect was also investigated.

  9. Phase Transformation and Shape Memory Effect of Ti-Pd-Pt-Zr High-Temperature Shape Memory Alloys

    Science.gov (United States)

    Yamabe-Mitarai, Yoko; Takebe, Wataru; Shimojo, Masayuki

    2017-12-01

    To understand the potential of high-temperature shape memory alloys, we have investigated the phase transformation and shape memory effect of Ti-(50 - x)Pt- xPd-5Zr alloys ( x = 0, 5, and 15 at.%), which present the B2 structure in the austenite phase and B19 structure in the martensite phase. Their phase transformation temperatures are very high; A f and M f of Ti-50Pt are 1066 and 1012 °C, respectively. By adding Zr and Pd, the phase transition temperatures decrease, ranging between 804 and 994 °C for A f and 590 and 865 °C for M f. Even at the high phase transformation temperature, a maximum recovery ratio of 70% was obtained for one cycle in a thermal cyclic test. A work output of 1.2 J/cm3 was also obtained. The recovery ratio obtained by the thermal cyclic test was less than 70% because the recovery strain was < 1% and a large irrecoverable strain was obtained. The shape recovery was explained by the austenite strength. The training effect was also investigated.

  10. Temperature effect on high salinity depuration of Vibrio vulnificus and V. parahaemolyticus from the Eastern oyster (Crassostrea virginica).

    Science.gov (United States)

    Larsen, A M; Rikard, F S; Walton, W C; Arias, C R

    2015-01-02

    Vibrio vulnificus (Vv) and Vibrio parahaemolyticus (Vp) are opportunistic human pathogens naturally associated with the Eastern oyster Crassostrea virginica. The abundances of both pathogens in oysters are positively correlated with temperature, thus ingestion of raw oysters during the warm summer months is a risk factor for contracting illness from these bacteria. Current post-harvest processing (PHP) methods for elimination of these pathogens are expensive and kill the oyster, changing their organoleptic properties and making them less appealing to some consumers. High salinity has proven effective in reducing Vv numbers in the wild and our research aims at developing an indoor recirculating system to reduce pathogenic Vibrios while maintaining the taste and texture of live oysters. The goal of this study was to determine the influence of temperature on the efficacy of high salinity depuration. Vv was enumerated as most probable number (MPN) per gram of oyster tissue using the FDA-approved modified cellobiose polymyxin colistin (mCPC) protocol and with an alternative Vibrio specific media CHROMagar™ Vibrio (CaV). CaV was also used to quantify Vp. Oysters were held at 35 psu for 10 days at three temperatures: low (20°C), mid (22.5°C) and high (25°C). There was no difference in MPN/g of Vv between media; however more Vv isolates were obtained from mCPC than CaV. There was no significant effect of temperature on reduction of Vv or Vp throughout depuration but there was a tendency for low temperatures to be less effective than the higher ones. High salinity resulted in a significant decrease in Vv by day 3 and again by day 10, and a decrease in Vp by day 3. Oyster condition indices were maintained throughout depuration and mortality was low (4% across three trials). Overall these results support the use of mCPC for Vv enumeration and demonstrate the promise of high salinity depuration for PHP of the Eastern oyster. The trend for lower temperatures to be less

  11. Effect of Curing Temperature on the Durability of Concrete under Highly Geothermal Environment

    National Research Council Canada - National Science Library

    Yang Tang; Hui Su; Shun Huang; Chunlai Qu; Jiaqi Yang

    2017-01-01

      To determine the durability of concrete in the actual temperature and humidity of the tunnel environment, this study investigates the mechanical properties, permeability of chloride ion, relative...

  12. THE EFFECT OF HIGH TEMPERATURE ON THE POROSITY AND COMPRESSiVE STRENGTH ON THE CARBON FIBER REINFORCED LIGHTWEIGHT CONCRETE

    OpenAIRE

    DEMİREL, Bahar; GÖNEN, Tahir

    2008-01-01

    In this study, the effect of high temperature on the mechanical properties of the carbon fiber reinforced lightweight concrete with silica fume was investigated. With this aim, lightweight concrete samples were produced by using basaltic pumice (scoria) obtained from Elazig region. In addition, the samples produced with and without silica fume and carbon fiber. Silica fume was replaced 10 % by weight of cement and carbon fiber was added 0.5 % by weight of cement. Four different series of samp...

  13. Effect of sulfur on the protective layers on alloys 600 and 690 in low and high temperature environments

    Energy Technology Data Exchange (ETDEWEB)

    Combrade, P.; Foucault, M.; Vancon, D. (Unirec, 42 - Firminy (FR)); Marcus, P.; Grimal, J.M. (Ecole Nationale Superieure de Chimie, 75 - Paris (FR)); Gelpi, A. (Societe Franco-Americaine de Constructions Atomiques (Framatome), 92 - Courbevoie (FR))

    The effect of the presence of sulfide dissolved in the environment on the dissolution and film repair was studied on alloy 600, alloy 690 and nickel exposed to neutral and caustic deaerated solutions at 290{sup 0}C. Comparison with the effect of adsorbed sulfur on the dissolution and film built up on high purity alloy 600 and nickel in acidic solutions at room temperature shows strong analogies. In both cases the beneficial effect of chromium is clearly shown and this is consistent with the better behaviour of alloy with increased chromium content such as alloy 690.

  14. (Krauss) at constant high temperatures

    African Journals Online (AJOL)

    Snail Research Unit of the SAMRC and Department of Zoology, Potchefstroom University for CHE,. Potchefstroom. The survival of the freshwater snail species Bulinus africanus, Bulinus g/obosus and Biompha/aria pfeifferi at extreme high temperatures was experimentally investigated. Snails were exposed to temperatures ...

  15. HIGH TEMPERATURE POLYMER FUEL CELLS

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Qingfeng, Li; He, Ronghuan

    2003-01-01

    This paper will report recent results from our group on polymer fuel cells (PEMFC) based on the temperature resistant polymer polybenzimidazole (PBI), which allow working temperatures up to 200°C. The membrane has a water drag number near zero and need no water management at all. The high working...

  16. The effect of low temperatures on the fatigue of high-strength structural grade steels

    NARCIS (Netherlands)

    Walters, C.L.

    2014-01-01

    It is well-known that for fracture, ferritic steels undergo a sudden transition from ductile behavior at higher temperatures to brittle cleavage failure at lower temperatures. However, this phenomenon has not received much attention in the literature on fatigue. The so-called Fatigue Ductile-Brittle

  17. Effect of Curing Temperature on the Durability of Concrete under Highly Geothermal Environment

    Directory of Open Access Journals (Sweden)

    Yang Tang

    2017-01-01

    Full Text Available To determine the durability of concrete in the actual temperature and humidity of the tunnel environment, this study investigates the mechanical properties, permeability of chloride ion, relative dynamic elastic modulus, and mass loss ratio of concrete specimens cured in the temperature which varied from normal, 40, 60, 75, and 90°C, and the humidity was kept at 90% continuously. Experimental results reveal that the hot temperature curing environment may benefit early stage strength development but reduce the long-term strength. It is proved that 60°C is a critical point. At above 60°C, the strength of the concrete material and its resistance to chloride ion permeability showed a decreasing trend; however, in the appropriate temperature range, the frost resistance properties of the concrete are improved with increasing temperature.

  18. The effect of high temperatures on the electrical characteristics of Au/n-GaAs Schottky diodes

    Science.gov (United States)

    Tunhuma, S. M.; Auret, F. D.; Legodi, M. J.; Diale, M.

    2016-01-01

    In this study, the current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Au/n-GaAs Schottky diodes have been measured over a wide temperature range, 80-480 K. The diodes were rectifying throughout the range and showed good thermal stability. Room temperature values for the ideality factor, I-V barrier height and C-V barrier height were found to be n=1.10, ϕIV=0.85 eV and ϕCV=0.96 eV, respectively. ϕIV increases and n decreases with an increase in temperature. We investigated the effect of elevated temperatures on the barrier height and ideality factor by measuring the diodes at a high temperature (annealing mode) then immediately afterwards measuring at room temperature (post annealing mode). The measurements indicate I-V characteristics that degrade permanently above 300 K. Permanent changes to the C-V characteristics were observed only above 400 K. We also noted a discrepancy in the C-V barrier height and carrier concentration between 340 and 400 K, which we attribute to the influence of the EL2 defect (positioned 0.83 eV below the conduction band minima) on the free carrier density. Consequently, we were able to fit the ϕCV versus temperature curve into two regions with temperature coefficients -6.9×10-4 eV/K and -2.2×10-4 eV/K above and below 400 K.

  19. Multiple generation effects of high temperature on the development and fecundity of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype B.

    Science.gov (United States)

    Guo, Jian-Ying; Cong, Lin; Wan, Fang-Hao

    2013-08-01

    Insects are ectotherms and their ability to resist temperature stress is limited. The immediate effects of sub-lethal heat stress on insects are well documented, but longer-term effects of such stresses are rarely reported. In this study, survival, development and reproduction of the whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype B, were compared over five consecutive generations at 27, 31 and 35 °C and for one generation at 37 °C. Both temperature and generation significantly affected the fitness of the whitefly. These impacts were more dramatic with increasing generations and temperatures. Among the experimental temperatures, the most favorable for development and reproduction were 27 °C and 31 °C. At 27 °C, survival, development and fecundity were all stable over these five generations. At 31 °C, immature survival rate was the highest in the fifth generation, but female fecundities decreased in the fourth and fifth generations. At 35 °C, egg hatching rate, immature survival rate and female fecundity decreased significantly in the fourth and fifth generations. At 37 °C, survival of B. tabaci was not adversely affected, but female fecundity at 37 °C was less than 10% of that at 27 °C or 31 °C. These results demonstrate that the lethal high temperature for B. tabaci is over 37 °C, and the whitefly population continued expanding in the five generations at 35 °C. The ability of B. tabaci biotype B to survive high temperature stress will play an important role in its population extension under global warming. © 2012 The Authors Insect Science © 2012 Institute of Zoology, Chinese Academy of Sciences.

  20. Decoupling of quark condensate from the effective nucleon mass at high density ({rho}) and temperature (T)

    Energy Technology Data Exchange (ETDEWEB)

    Delfino, A.; Dey, Jishnu; Malheiro, M. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Fisica; Day, Mira [UNESP, SP (Brazil). Inst. de Fisica

    1995-05-26

    It is found that the quark condensate (qq), instead of decreasing at high {rho}, as commonly expected, starts to increase after a certain density ({approx}1.5{sub {rho}o}), - in standard relativistic nuclear matter models. When the models contain coupling constants which are density dependent, (qq) -> 0 at high {rho} and T, but the effective nucleon mass changes little, showing a decoupling of the mass from the condensate. It is remarkable that (qq) is independent of the hadronic models we choose, up to {rho} {approx} {rho}{sub o}. (author) 15 refs., 8 figs.; e-mail: jdey at ift.uesp.ansp.br; mdey at ift.uesp.ansp.br

  1. High Temperature Bell Motor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The National Research Council (NRC) has identified the need for motors and actuators that can operate in extreme high and low temperature environments as a technical...

  2. High Temperature Materials Laboratory (HTML)

    Data.gov (United States)

    Federal Laboratory Consortium — The six user centers in the High Temperature Materials Laboratory (HTML), a DOE User Facility, are dedicated to solving materials problems that limit the efficiency...

  3. THE EFFECT OF HIGH TEMPERATURE ON THE POROSITY AND COMPRESSiVE STRENGTH ON THE CARBON FIBER REINFORCED LIGHTWEIGHT CONCRETE

    Directory of Open Access Journals (Sweden)

    Bahar DEMİREL

    2008-02-01

    Full Text Available In this study, the effect of high temperature on the mechanical properties of the carbon fiber reinforced lightweight concrete with silica fume was investigated. With this aim, lightweight concrete samples were produced by using basaltic pumice (scoria obtained from Elazig region. In addition, the samples produced with and without silica fume and carbon fiber. Silica fume was replaced 10 % by weight of cement and carbon fiber was added 0.5 % by weight of cement. Four different series of samples were prepared in order to observe the effect of high temperature on the physical and mechanical properties of both the lightweight concrete with and without silica fume and the lightweight concrete with and without carbon fiber. The specimens completed the 365 days curing period were exposed to 250, 500, 750 and 1000 °C for 1 hour. Porosity and compressive strength were determined and recorded after the specimens were cooled at the room temperature. In conclusion, it is determined that the losing of compressive strength in the specimens with silica fume is higher than the others. Relation of compressive strength-porosity is high out of 500-750 °C.

  4. The effect of low and high barn temperatures on behaviour and performance of Holstein dairy cows

    Directory of Open Access Journals (Sweden)

    Milan Večeřa

    2012-01-01

    Full Text Available The experiment was carried out at the University Training Farm in Žabčice (the Czech Republic; location 49°0’51.081”N, 16°36’14.848”E, 179 m.a.s.l over the period of one year (1st July to 30th June. The assessment of temperature impact was based on data from 16 hottest days (H and 16 coldest days (L. The experimental group consisted of 70 cows in various stage of lactation (30d–210d and parity (1–8. The cows were housed in a section (one quarter of a free-stall barn with 77 stalls in three rows. Row A was located peripherally, close to the side wall, row B was in the middle and row C was situated centrally, close to the feed table. The cows were observed weekly on the same day at 9.00 a.m. The microclimate characteristics were recorded daily: temperature in hot (H resp. cold (L period was in average 27.1°C resp. – 1.47 °C, and relative humidity 54.4 % resp. 77.3 %, and THI 75 resp. 33.Behaviour was described by a number of cows standing or lying down, number of cows lying down on their left or right side and row preference (A, B, C in the resting area. Cow Comfort Index (CCI – a number of cows lying down at given time was calculated. A total of 1587 observations were analysed. A number of cows lying down (922 was significantly higher than that of standing cows (665. Milk production was significantly higher in hot (H period (by 1.0–1.7 kg. There was an interaction in milk production between period and standing. In H period the standing cows produced more milk, in L period vice versa. The cows with non-significant tendency towards left-side laterality produced more milk (by 1.2 kg. No interaction was found between period and laterality for milk production. All the observed parameters significantly differed between rows A, B and C. Row A was the most preferred, the cows preferring it were young (low number of lactation with greatest milk production. The cows in row C had the lowest milk production and were in late

  5. Effect of niobium interlayer on high-temperature sliding friction and wear of silver films on alumina

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.; Erck, R.A.

    1994-03-01

    We investigated the effect of a thin Nb bond layer (15--20 mn thick) on the high-temperature sliding friction and wear of silver films ({approx}1.5 {mu}m thick) produced on {alpha}-alumina (Al{sub 2}O{sub 3}) substrates by ion-beam assisted deposition. The friction coefficients of test pairs without an Ag film fluctuated between 0.8 to 1.1, whereas the friction coefficients of pairs with an Ag film were 0.32 to 0.5. The wear of uncoated Al{sub 2}O{sub 3} balls sliding against the Ag-coated flats was reduced by factors of 25 to {approx}2000, depending on test temperature and the presence or absence of an Nb bond layer. The wear of silver-coated flats was virtually unmeasurable after tests at temperatures up to 400C. At much higher temperatures (e.g., 600C), Ag films without an Nb bond layer delaminated from the sliding surfaces and lost their effectiveness; however, Ag films with an Nb bond layer remained intact on the sliding surfaces of the Al{sub 2}O{sub 3} substrates even at 600C and continued to impart low friction and low wear.

  6. Low temperature synthesis of nanocrystalline magnesium aluminate with high surface area by surfactant assisted precipitation method: Effect of preparation conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mosayebi, Zeinab [Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Rezaei, Mehran, E-mail: rezaei@kashanu.ac.ir [Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of); Hadian, Narges [Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Kordshuli, Fazlollah Zareie [Shiraz Petrochemical Co., Shiraz (Iran, Islamic Republic of); Meshkani, Fereshteh [Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of)

    2012-09-15

    Highlights: ► MgAl{sub 2}O{sub 4} showed a high surface area and nanocrystalline structure. ► Addition of polymeric surfactant affected the structural properties of MgAl{sub 2}O{sub 4}. ► MgAl{sub 2}O{sub 4} prepared with surfactant showed a hollow cylindrical shape. -- Abstract: A surfactant assisted co-precipitation method was employed for the low temperature synthesis of magnesium aluminate spinel with nanocrystalline size and high specific surface area. Pluronic P123 triblock copolymer and ammonia solution were used as surfactant and precipitation agent, respectively. The prepared samples were characterized by thermal gravimetric and differential thermal gravimetric analyses (TG/DTG), X-ray diffraction (XRD), N{sub 2} adsorption (BET) and transmission electron microscopy (TEM) techniques. The effects of several process parameters such as refluxing temperature, refluxing time, pH, P123 to metals mole ratio (P123/metals) and calcination temperature on the structural properties of the samples were investigated. The obtained results showed that, among the process parameters pH and refluxing temperature have a significant effect on the structural properties of samples. The results revealed that increase in pH from 9.5 to 11 and refluxing temperature from 40 °C to 80 °C increased the specific surface area of prepared samples in the range of 157–188 m{sup 2} g{sup −1} and 162–184 m{sup 2} g{sup −1}, respectively. The XRD analysis showed the single-phase MgAl{sub 2}O{sub 4} was formed at 700 °C.

  7. Effect of fast pyrolysis conditions on biomass solid residues at high temperatures

    DEFF Research Database (Denmark)

    Trubetskaya, Anna; Jensen, Peter Arendt; Jensen, Anker Degn

    2016-01-01

    Fast pyrolysis of wood and straw was conducted in a drop tube furnace (DTF) and compared with corresponding data from a wire mesh reactor (WMR) to study the influence of temperature (1000-1400)°C, biomass origin (pinewood, beechwood, wheat straw, alfalfa straw), and heating rate (103 °C/s, 104 °C...... in its half-width with respect to the parental fuel, whereas the alfalfa straw char particle size remained unaltered at higher temperatures. Soot particles in a range from 60 to 300 nm were obtained during fast pyrolysis. The soot yield from herbaceous fuels was lower than from wood samples, possibly due...

  8. 15 MeV proton irradiation effects on Bi-based high temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Alinejad, N.; Sohrabi, D. [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of). Plasma and Nuclear Fusion Research School; Bolori, F. [Karaj Agricultural, Medical, and Industrial Research School, Karaj (Iran, Islamic Republic of)

    2015-11-15

    Nowadays, superconducting magnetic coils are used in some tokamaks such as EAST, KSTAR, JT-60, and T-15 to generate strong magnetic fields and also in ITER magnetic fields of about 13 tesla will be produced with the help of superconductors. The tokamak superconductors are exposed to the variety of radiations (neutron, ions beam, and gamma) from plasma nuclear reactions which will affect some of the superconductor properties. Therefore, study of the irradiation effects on the superconductor structure and properties are very crucial from technological and scientific point of view. One of the superconductor irradiation effects to be investigated under different conditions of energy and dosage is the potential resistance of the material used in tokamak reactor magnetic coils against activation by radiation. In this work, pellets of high T{sub c} Bi-based superconductors have been prepared and after measurement of parameters, a sample of pellet has been irradiated with 15 MeV protons using Karaj cyclotron facility. The sample's parameters have been measured again after irradiation treatment. X-ray diffraction patterns and SEM images of the sample before and after irradiation treatment have been studied.

  9. Vitamin C prevents the effects of high rearing temperatures on the quality of broiler thigh meat1.

    Science.gov (United States)

    Ferreira, I B; Matos Junior, J B; Sgavioli, S; Vicentini, T I; Morita, V S; Boleli, I C

    2015-05-01

    We investigated the effects of incubation temperatures and vitamin C injections into eggs (treatments: 37.5ºC, 39ºC, 39ºC+vitamin C) on resultant chick pectoralis major and sartorius muscle fiber hypertrophy, as well as their effects on the quality of breast and over-thigh meat of broilers reared under cold, control, or hot temperatures. Incubation at 39ºC increased the shear force and reduced meat redness in breast meat (P high temperature incubation effects [shear force (kgf cm(-2)): 37.5ºC = 2.34, 39ºC = 2.79, 39ºC+vitamin C = 2.44; redness: 37.5ºC = 2.64, 39ºC = 1.90, 39ºC+vitamin C = 2.30], but reduced water content (37.5ºC = 74.81%, 39ºC = 74.53%, 39ºC+vitamin C = 69.39%) (P temperatures increased breast meat redness (a*: cold = 2.78, control = 2.12, hot = 1.98), while hot rearing temperatures reduced the muscle fiber area (cold = 5.413 μm(2), control = 5.612 μm(2), hot = 4.448 μm(2)) (P 0.05). Hot rearing temperatures increased the cooking loss (cold = 30.10%, control = 33.66%, hot = 37.01%), shear force (cold = 3.05 kgf cm(-2), control = 3.43 kgf cm(-2), hot = 4.29 kgf cm(-2)) and redness (a*: cold = 4.63, control = 3.55, hot = 3.20) in the over-thigh meat of broilers from eggs incubated at 37.5ºC, increasing the area of muscle fibers, while cold rearing temperatures diminished cooking loss and shear force, reducing the muscle fiber area (P temperatures, by diminishing and increasing the muscle fiber area, respectively. © 2015 Poultry Science Association Inc.

  10. Investigations into High Temperature Components and Packaging

    Energy Technology Data Exchange (ETDEWEB)

    Marlino, L.D.; Seiber, L.E.; Scudiere, M.B.; M.S. Chinthavali, M.S.; McCluskey, F.P.

    2007-12-31

    temperature increase inside the device due the internal heat that is generated due to conduction and switching losses. Capacitors and high current switches that are reliable and meet performance specifications over an increased temperature range are necessary to realize electronics needed for hybrid-electric vehicles (HEVs), fuel cell (FC) and plug-in HEVs (PHEVs). In addition to individual component level testing, it is necessary to evaluate and perform long term module level testing to ascertain the effects of high temperature operation on power electronics.

  11. Effect of high-temperature heat treatment duration on the purity and ...

    Indian Academy of Sciences (India)

    This method involves decom- position of hydrocarbons at a prescribed temperature and pressure under controlled quantities of catalysts [1]. In gen- eral, either transition metals (d-block elements like iron, nickel, etc.) or organometallic complexes (e.g., ferrocene) are decomposed to generate the metal catalyst. Although cat-.

  12. High Cooling Water Temperature Effects on Design and Operational Safety of NPPs in the Gulf Region

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Byung Koo [Khalifa Univ., Abu Dhabi (United Arab Emirates); Jeong, Yong Hoon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2013-12-15

    The Arabian Gulf region has one of the highest ocean temperatures, reaching above 35 degrees and ambient temperatures over 50 degrees in the summer. Two nuclear power plants (NPP) are being introduced in the region for the first time, one at Bushehr (1,000 MWe PWR plant from Russia), and a much larger one at Barakah (4Χ1,400 MWe PWR from Korea). Both plants take seawater from the Gulf for condenser cooling, having to modify the secondary/tertiary side cooling systems design by increasing the heat transfer surface area from the country of origin. This paper analyses the secondary side of a typical PWR plant operating under the Rankine cycle with a simplified thermal-hydraulic model. Parametric study of ocean cooling temperatures is conducted to estimate thermal efficiency variations and its associated design changes for the secondary side. Operational safety is reviewed to deliver rated power output with acceptable safety margins in line with technical specifications, mainly in the auxiliary systems together with the cooling water temperature. Impact on the Gulf seawater as the ultimate heat sink is considered negligible, affecting only the adjacent water near the NPP site, when compared to the solar radiation on the sea surface.

  13. HIGH COOLING WATER TEMPERATURE EFFECTS ON DESIGN AND OPERATIONAL SAFETY OF NPPS IN THE GULF REGION

    Directory of Open Access Journals (Sweden)

    BYUNG KOO KIM

    2013-12-01

    Full Text Available The Arabian Gulf region has one of the highest ocean temperatures, reaching above 35 degrees and ambient temperatures over 50 degrees in the summer. Two nuclear power plants (NPP are being introduced in the region for the first time, one at Bushehr (1,000 MWe PWR plant from Russia, and a much larger one at Barakah (4X1,400 MWe PWR from Korea. Both plants take seawater from the Gulf for condenser cooling, having to modify the secondary/tertiary side cooling systems design by increasing the heat transfer surface area from the country of origin. This paper analyses the secondary side of a typical PWR plant operating under the Rankine cycle with a simplified thermal-hydraulic model. Parametric study of ocean cooling temperatures is conducted to estimate thermal efficiency variations and its associated design changes for the secondary side. Operational safety is reviewed to deliver rated power output with acceptable safety margins in line with technical specifications, mainly in the auxiliary systems together with the cooling water temperature. Impact on the Gulf seawater as the ultimate heat sink is considered negligible, affecting only the adjacent water near the NPP site, when compared to the solar radiation on the sea surface.

  14. Study of the Real Gas Effects of Nitrogen and Air at High Densities and Temperatures

    Science.gov (United States)

    1975-01-01

    impurities are mainly residuals of oxygen. supplied by Air Liquide 46 AEDC-TR-74-47 hydrogen and vater vapour. To minimise further contaminants...the year. Corrections for this temperature to initial entropy supplied by Air Liquide 47 AEOC-TR-74-47 are made in the final data reduction. During

  15. RPC operation at high temperature

    CERN Document Server

    Aielli, G; Cardarelli, R; Di Ciaccio, A; Di Stante, L; Liberti, B; Paoloni, A; Pastori, E; Santonico, R

    2003-01-01

    The resistive electrodes of RPCs utilised in several current experiments (ATLAS, CMS, ALICE, BABAR and ARGO) are made of phenolic /melaminic polymers, with room temperature resistivities ranging from 10**1**0 Omega cm, for high rate operation in avalanche mode, to 5 multiplied by 10**1**1 Omega cm, for streamer mode operation at low rate. The resistivity has however a strong temperature dependence, decreasing exponentially with increasing temperature. We have tested several RPCs with different electrode resistivities in avalanche as well as in streamer mode operation. The behaviours of the operating current and of the counting rate have been studied at different temperatures. Long-term operation has also been studied at T = 45 degree C and 35 degree C, respectively, for high and low resistivity electrodes RPCs.

  16. Moire interferometry at high temperatures

    Science.gov (United States)

    Wu, Jau-Je

    1992-01-01

    The objective of this study was to provide an optical technique allowing full-field in-plane deformation measurements at high temperature by using high-sensitivity moire interferometry. This was achieved by a new approach of performing deformation measurements at high temperatures in a vacuum oven using an achromatic interferometer. The moire system setup was designed with particular consideration for the stability, compactness, flexibility, and ease of control. A vacuum testing environment was provided to minimize the instability of the patterns by protecting the optical instruments from the thermal convection currents. Also, a preparation procedure for the high-temperature specimen grating was developed with the use of the plasma-etched technique. Gold was used as a metallic layer in this procedure. This method was demonstrated on a ceramic block, metal/matrix composite, and quartz. Thermal deformation of a quartz specimen was successfully measured in vacuum at 980 degrees Celsius, with the sensitivity of 417 nm per fringe. The stable and well-defined interference patterns confirmed the feasibility of the developments, including the high-temperature moire system and high-temperature specimen grating. The moire system was demonstrated to be vibration-insensitive. Also, the contrast of interference fringes at high temperature was enhanced by means of a spatial filter and a narrow band interference filter to minimize the background noise from the flow of the specimen and heater. The system was verified by a free thermal expansion test of an aluminum block. Good agreement demonstrated the validity of the optical design. The measurements of thermal deformation mismatch were performed on a graphite/epoxy composite, a metal/matrix composite equipped with an optical fiber, and a cutting tool bit. A high-resolution data-reduction technique was used to measure the strain distribution of the cutting tool bit.

  17. High temperature superconductor accelerator magnets

    OpenAIRE

    van Nugteren, J.

    2016-01-01

    For future particle accelerators bending dipoles are considered with magnetic fields exceeding 20T. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and development before they can be applied in a practical accelerator magnet. In order to study HTS in detail, a five tesla demonstrator magnet named Feather-M2 is designed and constructed. The magnet is ...

  18. High Temperature Superconductor Accelerator Magnets

    OpenAIRE

    Van Nugteren, Jeroen; ten Kate, Herman; de Rijk, Gijs; Dhalle, Marc

    2016-01-01

    For future particle accelerators bending dipoles are considered with magnetic fields exceeding $20T$. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and development before they can be applied in a practical accelerator magnet. In order to study HTS in detail, a five tesla demonstrator magnet named Feather-M2 is designed and constructed. The magnet ...

  19. Effect of high shear mixing parameters and degassing temperature on the morphology of epoxy-clay nanocomposites

    KAUST Repository

    Al-Qadhi, Muneer

    2013-01-01

    Epoxy-clay nanocomposites were prepared by high shear mixing method using Nanomer I.30E nanoclay as nano-reinforcement in diglycidyl ether of bisphenol A (DGEBA). The effect of mixing speed and time on the nature and degree of clay dispersion were investigated by varying the mixing speed in the range of 500-8000 RPM and mixing time in the range of 15-90 minutes. The effect of degassing temperature on the morphology of the resultant nanocomposites was also studied. Scanning and transmission microscopy (SEM and TEM) along with x-ray diffraction (XRD) have been used to characterize the effect of shear mixing speed, mixing time and degassing temperature on the structure of the resultant nanocomposites. The SEM, TEM and XRD examinations demonstrated that the degree of clay dispersion was improved with increasing the high shear mixing speed and mixing time. The results showed that the optimum high shear mixing speed and mixing time were 6000 rpm and 60 min, respectively. It was observed that the structure of the nanocomposites that have been degassed at 65°C was dominated by ordered intercalated morphology while disordered intercalated with some exfoliated morphology was found for the sample degassed at 100°C for the first 2 hours of the degassing process. © (2013) Trans Tech Publications, Switzerland.

  20. Effects of high hydrostatic pressure and temperature increase on Escherichia coli spp. and pectin methyl esterase inactivation in orange juice.

    Science.gov (United States)

    Torres, E F; González-M, G; Klotz, B; Rodrigo, D

    2016-03-01

    The aim of this study was to evaluate the effect of high hydrostatic pressure treatment combined with moderate processing temperatures (25 ℃-50 ℃) on the inactivation of Escherichia coli O157: H7 (ATCC 700728), E. coli K12 (ATCC 23716), and pectin methyl esterase in orange juice, using pressures of 250 to 500 MPa with times ranging between 1 and 30 min. Loss of viability of E. coli O157:H7 increased significantly as pressure and treatment time increased, achieving a 6.5 log cycle reduction at 400 MPa for 3 min at 25 ℃ of treatment. With regard to the inactivation of pectin methyl esterase, the greatest reduction obtained was 90.05 ± 0.01% at 50 ℃ and 500 MPa of pressure for 15 min; therefore, the pectin methyl esterase enzyme was highly resistant to the treatments by high hydrostatic pressure. The results obtained in this study showed a synergistic effect between the high pressure and moderate temperatures in inactivating E. coli cells. © The Author(s) 2016.

  1. Characteristics of lactic acid bacteria isolates and their inoculating effects on the silage fermentation at high temperature.

    Science.gov (United States)

    Chen, M M; Liu, Q H; Xin, G R; Zhang, J G

    2013-01-01

    Thermotolerant strains of lactic acid bacteria (LAB) were screened for their suitability for silage making at high temperatures. Four selected strains were identified by 16S rRNA sequencing analyses and added to unwilted and wilted Italian ryegrass for ensiling at 45°C. All four strains (HT1, HT2, HT3 and HT4) grew at 50°C and pH 4·0. Strains HT1 and HT2 were identified as Lactobacillus rhamnosus; HT3 and HT4 were identified as Lact. fermentum. Strains HT1 and HT2 were the most effective at improving the fermentation quality of Italian ryegrass silage, irrespective of wilting, as indicated by lower pH values, less NH(3) -N, and more lactic acid. In contrast, strains HT3, HT4 and a commercial inoculant consisting of Lact. plantarum and Pediococcus acidilactici conferred no or reduced benefits. Wilting alone did not improve the fermentation quality of Italian ryegrass at 45°C. Inoculating with thermotolerant Lact. rhamnosus HT1 and HT2 could improve the fermentation quality of silage at high temperatures. Lactobacillus rhamnosus HT1 and HT2 can be used as inoculants for silage making in the tropics and subtropics and could play an important role in developing silage production in such regions. Grasses are often difficult to ensile in the tropics and subtropics because of the high temperatures there. To solve this problem, we screened for thermotolerant lactic acid bacteria and obtained two valuable strains of Lactobacillus rhamnosus, HT1 and HT2, which proved to be beneficial to silage fermentation at high temperatures. Lactobacillus rhamnosus HT1 and HT2 can be used as inoculants for silage making in the tropics and subtropics, and will play an important role in developing silage production in such regions. © 2012 The Society for Applied Microbiology.

  2. The effects of frequency on the elastic wave velocity in rocks at high temperatures under pressure

    Science.gov (United States)

    Matsushima, S.

    1986-04-01

    P- and S-wave velocities in nepheline basalt, Hamada, as well as diabase, Maryland, were measured experimentally to 1000°C and 2.5 GPa. A remarkable frequency dependence of large velocity-decrease was observed for both P- and S-waves at temperatures above 500°C. Remarkable velocity-characteristics, which cannot be explained by the existing theories, were: (1) Velocities were decreased considerably at 1-3 MHz. Above 3 MHz, samples showed elastic behavior like that of a perfect solid, and below 1 MHz, velocity-decrease decayed gradually. (2) Both P- and S-wave velocities decreased in the same way and almost to the same degree. (3) The higher the temperature, the more remarkably velocities decreased, at least up to the experimental limit temperature. A hypothesis of the relaxation of stress waves by the fluid-flow in the inclusions is proposed. Examples of geophysical applications are given for the attenuation and travel-time anomalies in the volcanic region and the P- and S-wave velocity-decrease in the upper mantle beneath continents.

  3. High-Temperature Optical Sensor

    Science.gov (United States)

    Adamovsky, Grigory; Juergens, Jeffrey R.; Varga, Donald J.; Floyd, Bertram M.

    2010-01-01

    A high-temperature optical sensor (see Figure 1) has been developed that can operate at temperatures up to 1,000 C. The sensor development process consists of two parts: packaging of a fiber Bragg grating into a housing that allows a more sturdy thermally stable device, and a technological process to which the device is subjected to in order to meet environmental requirements of several hundred C. This technology uses a newly discovered phenomenon of the formation of thermally stable secondary Bragg gratings in communication-grade fibers at high temperatures to construct robust, optical, high-temperature sensors. Testing and performance evaluation (see Figure 2) of packaged sensors demonstrated operability of the devices at 1,000 C for several hundred hours, and during numerous thermal cycling from 400 to 800 C with different heating rates. The technology significantly extends applicability of optical sensors to high-temperature environments including ground testing of engines, flight propulsion control, thermal protection monitoring of launch vehicles, etc. It may also find applications in such non-aerospace arenas as monitoring of nuclear reactors, furnaces, chemical processes, and other hightemperature environments where other measurement techniques are either unreliable, dangerous, undesirable, or unavailable.

  4. Part 2. Association of daily mortality with ambient air pollution, and effect modification by extremely high temperature in Wuhan, China.

    Science.gov (United States)

    Qian, Zhengmin; He, Qingci; Lin, Hung-Mo; Kong, Lingli; Zhou, Dunjin; Liang, Shengwen; Zhu, Zhichao; Liao, Duanping; Liu, Wenshan; Bentley, Christy M; Dan, Jijun; Wang, Beiwei; Yang, Niannian; Xu, Shuangqing; Gong, Jie; Wei, Hongming; Sun, Huilin; Qin, Zudian

    2010-11-01

    Fewer studies have been published on the association between daily mortality and ambient air pollution in Asia than in the United States and Europe. This study was undertaken in Wuhan, China, to investigate the acute effects of air pollution on mortality with an emphasis on particulate matter (PM*). There were three primary aims: (1) to examine the associations of daily mortality due to all natural causes and daily cause-specific mortality (cardiovascular [CVD], stroke, cardiac [CARD], respiratory [RD], cardiopulmonary [CP], and non-cardiopulmonary [non-CP] causes) with daily mean concentrations (microg/m3) of PM with an aerodynamic diameter--10 pm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), or ozone (O3); (2) to investigate the effect modification of extremely high temperature on the association between air pollution and daily mortality due to all natural causes and daily cause-specific mortality; and (3) to assess the uncertainty of effect estimates caused by the change in International Classification of Disease (ICD) coding of mortality data from Revision 9 (ICD-9) to Revision 10 (ICD-10) code. Wuhan is called an "oven city" in China because of its extremely hot summers (the average daily temperature in July is 37.2 degrees C and maximum daily temperature often exceeds 40 degrees C). Approximately 4.5 million residents live in the core city area of 201 km2, where air pollution levels are higher and ranges are wider than the levels in most cities studied in the published literature. We obtained daily mean levels of PM10, SO2, and NO2 concentrations from five fixed-site air monitoring stations operated by the Wuhan Environmental Monitoring Center (WEMC). O3 data were obtained from two stations, and 8-hour averages, from 10:00 to 18:00, were used. Daily mortality data were obtained from the Wuhan Centres for Disease Prevention and Control (WCDC) during the study period of July 1, 2000, to June 30, 2004. To achieve the first aim, we used a regression of

  5. Effects of Novel Fin Shape of High Temperature Heat Exchanger on 1 kW Class Stirling Engine

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Joon; Kim, Seok Yeon [Kookmin Univ., Seoul (Korea, Republic of)

    2017-08-15

    In this research, numerical analysis was carried out on novel and existing fins, adjusted in terms of factors such as length, spacing, and angle, of a high-temperature heat exchanger for a 1 kW class Stirling engine, designed as a prime mover for a domestic cogeneration system. The performance improvement as a result of shape optimization was confirmed with numerical analysis by including the air preheater, which was not considered during optimization. However, a negative heat flux was observed in the cylinder head portion. This phenomenon was clarified by analyzing the exhaust gas and wall surface temperature of the combustion chamber. Furthermore, assuming an ideal cycle, the effects of heat transfer enhancement on the thermodynamic cycle and system performance were predicted.

  6. Effect of chloride impurities on the performance and durability of polybenzimidazole-based high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Ali, Syed Talat; Li, Qingfeng; Pan, Chao

    2011-01-01

    . The performance loss was recovered when switching from the HCl solution back to pure water in the air humidifier. Under an accelerated aging performance test conducted through potential cycling between 0.9 V and 1.2 V, the PBI-based fuel cell initially containing 0.5 NaCl mg cm−2 on the cathode catalyst layer......The effect of chloride as an air impurity and as a catalyst contaminant on the performance and durability of polybenzimidazole (PBI)-based high temperature proton exchange membrane fuel cell (HT-PEMFC) was studied. The ion chromatographic analysis reveals the existence of chloride contaminations...... temperatures in 85% phosphoric acid containing chloride ions showed both increase in oxidation and reduction current densities. The fuel cell performance, i.e. the current density at a constant voltage of 0.4 V and 0.5 V was found to be degraded as soon as HCl was introduced in the air humidifier...

  7. Spin Seebeck effect and spin Hall magnetoresistance at high temperatures for a Pt/yttrium iron garnet hybrid structure.

    Science.gov (United States)

    Wang, Shuanhu; Zou, Lvkuan; Zhang, Xu; Cai, Jianwang; Wang, Shufang; Shen, Baogen; Sun, Jirong

    2015-11-14

    Based on unique experimental setups, the temperature dependences of the longitudinal spin Seebeck effect (LSSE) and spin Hall magnetoresistance (SMR) of the Pt/yttrium iron garnet (Pt/YIG) hybrid structure are determined in a wide temperature range up to the Curie temperature of YIG. From a theoretical analysis of the experimental relationship between the SMR and temperature, the spin mixing conductance of the Pt/YIG interface is deduced as a function of temperature. Adopting the deduced spin mixing conductance, the temperature dependence of the LSSE is well reproduced based on the magnon spin current theory. Our research sheds new light on the controversy about the theoretical models for the LSSE.

  8. The effect of low-temperature conditions on the electrochemical polymerization of polypyrrole films with high density, high electrical conductivity and high stability

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, C.O.; Sung, H.K.; Kim, J.H.; Barsoukov, E.; Kim, J.H.; Lee, H. [Korea Kumho Petrochem. Co. Ltd., Yuseong, Taejeon (Korea, Republic of). Kumho Chem. Labs.

    1999-02-26

    High-quality polypyrrole-hexafluorophosphate (PPy-PF{sub 6}) films with high density ({proportional_to}1.4 g/cm{sup 3}), high conductivity (>300 S/cm for unstretched film) and high electrochemical stability are obtained reproducibly by galvanostatic polymerization at low-temperature conditions. The optimal polymerization current density of J{sub p}=0.02-0.05 mA/cm{sup 2} was obtained at the polymerization temperature of T{sub p}=-40 C. The surface morphology of the film sensitively varies depending upon the properties of electrode and its surface conditions. The transport measurements characterize the high-density PPy-PF{sub 6} film as a disordered metal close to the boundary of disorder induced metal-insulator (M-I) transition. The X-ray diffraction measurements suggest that partially crystalline structure of PPy-PF{sub 6} film is related to the transport properties. The uniaxial stretching induces an increase of the conductivity up to {proportional_to}930 S/cm in a direction parallel to stretching as well as the anisotropy of conductivity. The comparative studies of thermogravimetric analysis (TGA), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) for PPy-PF{sub 6} films prepared at room-temperature and low-temperature conditions show that the latter exhibit better thermal stability as well as electrochemical stability under long oxidative polarization. (orig.) 33 refs.

  9. Effects of phosphorous-doping and high temperature annealing on CVD grown 3C-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Rooyen, I.J. van, E-mail: Isabella.vanrooyen@inl.gov [CSIR, National Laser Centre, PO Box 395, Pretoria 0001 (South Africa); Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Fuel Design, PBMR, 1279 Mike Crawford Avenue, Centurion 0046 (South Africa); Neethling, J.H. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Henry, A.; Janzen, E. [Department of Physics, Chemistry and Biology, Semiconductor Materials, Linkoeping University, Linkoeping 58183 (Sweden); Mokoduwe, S.M. [Fuel Design, PBMR, 1279 Mike Crawford Avenue, Centurion 0046 (South Africa); Janse van Vuuren, A.; Olivier, E. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa)

    2012-10-15

    The integrity and property behavior of the SiC layer of the Tri-isotropic (TRISO) coated particle (CP) for high temperature reactors (HTR) are very important as the SiC layer is the main barrier for gaseous and metallic fission product release. This study describes the work done on un-irradiated SiC samples prepared with varying phosphorus levels to simulate the presence of phosphorus due to transmutation. {sup 30}Si transmutes to phosphorous ({sup 31}P) and other transmutation products during irradiation, which may affect the integrity of the SiC layer. The P-doping levels of the SiC samples used in this study cover the range from 1.1 Multiplication-Sign 10{sup 15} to 1.2 Multiplication-Sign 10{sup 19} atom/cm{sup 3} and are therefore relevant to the PBMR operating conditions. Annealing from 1000 Degree-Sign C to 2100 Degree-Sign C was performed to study the possible changes in nanostructures and various properties due to temperature. Characterization results by X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM), are reported in this article. As grain boundary diffusion is identified as a possible mechanism by which {sup 110m}Ag, one of the fission activation products, might be released through intact SiC layer, grain size measurements is also included in this study. Temperature is evidently one of the factors/parameters amongst others known to influence the grain size of SiC and therefore it is important to investigate the effect of high temperature annealing on the SiC grain size. The ASTM E112 method as well as electron back scatter diffraction (EBSD) was used to determine the grain size of various commercial SiC samples and the SiC layer in experimental PBMR Coated Particles (CPs) after annealing at temperatures ranging from 1600 Degree-Sign C to 2100 Degree-Sign C. The HRTEM micrograph of the decomposition of Si

  10. Solute strengthening at high temperatures

    Science.gov (United States)

    Leyson, G. P. M.; Curtin, W. A.

    2016-08-01

    The high temperature behavior of solute strengthening has previously been treated approximately using various scaling arguments, resulting in logarithmic and power-law scalings for the stress-dependent energy barrier Δ E(τ ) versus stress τ. Here, a parameter-free solute strengthening model is extended to high temperatures/low stresses without any a priori assumptions on the functional form of Δ E(τ ) . The new model predicts that the well-established low-temperature, with energy barrier Δ {{E}\\text{b}} and zero temperature flow stress {τy0} , transitions to a near-logarithmic form for stresses in the regime 0.2intermediate-temperature and the associated transition for the activation volume. Overall, the present analysis unifies the different qualitative models in the literature and, when coupled with the previous parameter-free solute strengthening model, provides a single predictive model for solute strengthening as a function of composition, temperature, and strain rate over the full range of practical utility.

  11. High temperature superconductor current leads

    Science.gov (United States)

    Hull, John R.; Poeppel, Roger B.

    1995-01-01

    An electrical lead having one end for connection to an apparatus in a cryogenic environment and the other end for connection to an apparatus outside the cryogenic environment. The electrical lead includes a high temperature superconductor wire and an electrically conductive material distributed therein, where the conductive material is present at the one end of the lead at a concentration in the range of from 0 to about 3% by volume, and at the other end of the lead at a concentration of less than about 20% by volume. Various embodiments are shown for groups of high temperature superconductor wires and sheaths.

  12. High temperature corrosion in gasifiers

    Directory of Open Access Journals (Sweden)

    Wate Bakker

    2004-03-01

    Full Text Available Several commercial scale coal gasification combined cycle power plants have been built and successfully operated during the last 5-10 years. Supporting research on materials of construction has been carried out for the last 20 years by EPRI and others. Emphasis was on metallic alloys for heat exchangers and other components in contact with hot corrosive gases at high temperatures. In this paper major high temperature corrosion mechanisms, materials performance in presently operating gasifiers and future research needs will be discussed.

  13. Investigating the effects of methanol-water vapor mixture on a PBI-based high temperature PEM fuel cell

    DEFF Research Database (Denmark)

    Araya, Samuel Simon; Andreasen, Søren Juhl; Nielsen, Heidi Venstrup

    2012-01-01

    This paper investigates the effects of methanol and water vapor on the performance of a high temperature proton exchange membrane fuel cell (HT-PEMFC). A H3PO4-doped polybenzimidazole (PBI) membrane electrode assembly (MEA), Celtec P2100 of 45 cm2 of active surface area from BASF was employed....... A long-term durability test of around 1250 h was performed, in which the concentrations of methanol-water vapor mixture in the anode feed gas were varied. The fuel cell showed a continuous performance decay in the presence of vapor mixtures of methanol and water of 5% and 8% by volume in anode feed...

  14. Nonlinear plasmonics at high temperatures

    Science.gov (United States)

    Sivan, Yonatan; Chu, Shi-Wei

    2017-01-01

    We solve the Maxwell and heat equations self-consistently for metal nanoparticles under intense continuous wave (CW) illumination. Unlike previous studies, we rely on experimentally-measured data for metal permittivity for increasing temperature and for the visible spectral range. We show that the thermal nonlinearity of the metal can lead to substantial deviations from the predictions of the linear model for the temperature and field distribution and, thus, can explain qualitatively the strong nonlinear scattering from such configurations observed experimentally. We also show that the incompleteness of existing data of the temperature dependence of the thermal properties of the system prevents reaching a quantitative agreement between the measured and calculated scattering data. This modeling approach is essential for the identification of the underlying physical mechanism responsible for the thermo-optical nonlinearity of the metal and should be adopted in all applications of high-temperature nonlinear plasmonics, especially for refractory metals, for both CW and pulsed illumination.

  15. Nonlinear plasmonics at high temperatures

    Directory of Open Access Journals (Sweden)

    Sivan Yonatan

    2016-10-01

    Full Text Available We solve the Maxwell and heat equations self-consistently for metal nanoparticles under intense continuous wave (CW illumination. Unlike previous studies, we rely on experimentally-measured data for metal permittivity for increasing temperature and for the visible spectral range. We show that the thermal nonlinearity of the metal can lead to substantial deviations from the predictions of the linear model for the temperature and field distribution and, thus, can explain qualitatively the strong nonlinear scattering from such configurations observed experimentally. We also show that the incompleteness of existing data of the temperature dependence of the thermal properties of the system prevents reaching a quantitative agreement between the measured and calculated scattering data. This modeling approach is essential for the identification of the underlying physical mechanism responsible for the thermo-optical nonlinearity of the metal and should be adopted in all applications of high-temperature nonlinear plasmonics, especially for refractory metals, for both CW and pulsed illumination.

  16. Study on vapor film collapse behavior on high temperature particle surface. 2. Effect of subcooling on micro-mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Yutaka [Yamagata University, Dept. of Mechanical Systems Engineering, Yonezawa, Yamagata (Japan); Tochio, Daisuke [Yamagata Univ. (Japan)

    2000-02-01

    Thermal detonation model is proposed to describe vapor explosion. According to this model, vapor film on pre-mixed high temperature droplet surface should be collapsed for the trigger of the vapor explosion. It is pointed out that the vapor film collapse behavior is significantly affected by the subcooling of low temperature liquid. However, the effect of subcooling on micro-mechanism of vapor film collapse behavior is not experimentally well identified. The objective of the present research is to experimentally investigate the effect of subcooling on micro-mechanism of film boiling collapse behavior. As the results, it is experimentally clarified that the vapor film collapse behavior in low subcool condition is qualitatively different from the vapor film collapse behavior in high subcool condition. In high subcool condition, instability of the vapor film dominates the vapor film collapse on the particle surface. On the other hand, micro-mechanism at the interface between vapor and liquid such as micro-jet is dominant in low subcool condition in case of vapor film collapse by pressure pulse. (author)

  17. Effect of Bacillus cereus Enzymes on Milk Quality following Ultra High Temperature Processing

    Directory of Open Access Journals (Sweden)

    B. Janštová

    2006-01-01

    Full Text Available Using a model case of contamination of long-life semi-skimmed milk with the spores of six B. cereus strains, isolated from the farm environment and raw milk, proteolysis was monitored by measuring changes in protein content by infra-red spectroscopy; free tyrosine was measured by the Lowry method according to Juffs, and the reduction in casein fractions by SDS-PAGE. Lipolysis was monitored by the dilution extractive method. At a storage temperature of 4 °C for 4 months no enzyme processes were observed, whereas at a storage temperature of 24 °C a marked enzyme activity was found during maximum 3 weeks as well as sensory changes of UHT milk. After three weeks of storage, a reduction in protein content from 34.55 g l-1 milk to 29.46 ± 2.00 g l-1 milk, and a reduction in the free tyrosine from 0.65 to 2.13 ± 0.28 mg ml-1 was found, as well as increased molar contents of free fatty acids (FFA from 41.97 to 1617.22 ± 68.17 mmol kg-1 milk fat. After six days of storage, α-casein, β-casein and κ-casein dropped to 69 ± 10%, 56 ± 16% and 43 ± 10%, respectively. Majority of changes in UHT milk depended on the B. cereus strain used, initial microbial counts and the method of heat inactivation of spores.

  18. Evidence of effective axial U (1 ) symmetry restoration at high temperature QCD

    Science.gov (United States)

    Tomiya, A.; Cossu, G.; Aoki, S.; Fukaya, H.; Hashimoto, S.; Kaneko, T.; Noaki, J.; Jlqcd Collaboration

    2017-08-01

    We study the axial U (1 ) symmetry at a finite temperature in two-flavor lattice QCD. Employing the Möbius domain-wall fermions, we generate gauge configurations slightly above the critical temperature Tc with different lattice sizes L =2 - 4 fm . Our action allows frequent topology tunneling while keeping good chiral symmetry close enough to that of overlap fermions. This allows us to recover full chiral symmetry by an overlap/domain-wall reweighting. Above the phase transition, a strong suppression of the low-lying modes is observed in both overlap and domain-wall Dirac spectra. We, however, find a sizable violation of the Ginsparg-Wilson relation in the Möbius domain-wall Dirac eigenmodes, which dominates the signals of the axial U (1 ) symmetry breaking near the chiral limit. We also find that the use of the overlap fermion only in the valence sector is dangerous since it suffers from the artifacts due to partial quenching. Reweighting the Möbius domain-wall fermion determinant to that of the overlap fermion, we observe the axial U(1) breaking to vanish in the chiral limit, which is stable against the changes of the lattice volume and lattice spacing.

  19. High Pressure and Temperature Effects on the Viscosity, Density, and Bulk Modulus of Four Liquid Lubricants.

    Science.gov (United States)

    1978-01-01

    T Y Ct ., A ’ .’. I r ICA T I t > N Or T~ e I ’ P A r t (Ilk. ... ..~~.. l’nter. ,l) REPORT DOCU,~%ENTAT ION PAGE F .) ~~~~PORT N ~~~~‘,,.,__,. 2...I O N NAME AND A D D R E S S 10. P R O G R A M E L E M E,~l T , PROJ E CT TA S, ( M i d w e s t Research I n s t i t u t e A R E A S W O R K / P...the same time, The coil for tap water is used pr imar ily to hasten cooling of the bath. The bath liquid temperature is measured by ASTM extended—range

  20. The Effect of Ultrasonic Peening on Service Life of the Butt-Welded High-Temperature Steel Pipes

    Science.gov (United States)

    Daavari, Morteza; Vanini, Seyed Ali Sadough

    2015-09-01

    Residual stresses introduced by manufacturing processes such as casting, forming, machining, and welding have harmful effects on the mechanical behavior of the structures. In addition to the residual stresses, weld toe stress concentration can play a determining effect. There are several methods to improve the mechanical properties such as fatigue behavior of the welded structures. In this paper, the effects of ultrasonic peening on the fatigue life of the high-temperature seamless steel pipes, used in the petrochemical environment, have been investigated. These welded pipes are fatigued due to thermal and mechanical loads caused by the cycle of cooling, heating, and internal pressure fluctuations. Residual stress measurements, weld geometry estimation, electrochemical evaluations, and metallography investigations were done as supplementary examinations. Results showed that application of ultrasonic impact treatment has led to increased fatigue life, fatigue strength, and corrosion resistance of A106-B welded steel pipes in petrochemical corrosive environment.

  1. The Effect of High Pressure and Subzero Temperature on Gelation of Washed Cod and Salmon Meat.

    Science.gov (United States)

    Malinowska-Pańczyk, Edyta; Kołodziejska, Ilona

    2017-09-01

    The objective of the present work is to examine the influence of pressure up to 193 MPa at subzero temperature (without freezing of water) on myofibrillar proteins of salmon and cod meat and on the properties of gels obtained from washed mince of these fish. The solubility of proteins from myofibrils of cod and salmon meat suspended in 100 mM KCl solution increased after treating the samples with pressure above 60 MPa. The results of SDS- -PAGE analysis showed that under these conditions two myosin light chains, tropomyosin and troponin T were released from myofibrils. The solubility of proteins in 0.9 M NaCl solution of washed fish meat after pressure treatment at 60 MPa and -5 °C decreased to about 80-90% and at 193 MPa and -20 °C to 60%. Pressurization of cod meat decreased only slightly the solubility of proteins in SDS and urea solution and the solubility of salmon meat was similar to that in the unpressurized sample. There were no differences in the electrophoretic pattern of proteins from untreated and pressurized cod and salmon meat in the range of 60 to 193 MPa and -5 to -20 °C. The pressure treatment of washed salmon and cod meat at a temperature below 0 °C induced gelation; on the other hand, hardness of gels was lower by 28 and 26%, respectively, than that of gels formed by heating. The salmon and cod gels pressurized at 193 MPa and -20 °C and then heated were much harder than only pressurized or heated gels.

  2. The effect of firing temperature profiles for the high efficiency of crystalline Si solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Taeyoung; Kim, Sungchul; Kyung, Dohyeon; Jung, Woowon; Kim, Sunyong; Lee, Yongwoo; Kim, Youngkuk; Jang, Kyungsoo; Jung, Sungwook; Shin, Myungchul [School of Information and Communication Engineering, Sungkyunkwan University (SKKU), Suwon 440-746 (Korea); Yi, Junsin [School of Information and Communication Engineering, Sungkyunkwan University (SKKU), Suwon 440-746 (Korea); Department of Energy Science, Sungkyunkwan University (SKKU), Suwon 440-746 (Korea)

    2010-05-15

    In the mass production of crystalline Si solar cell, metallization is a very important process because it strongly affects various properties of the solar cell, such as I{sub sc}, V{sub oc}, R{sub s}, R{sub sh}, and FF. However, it is not easy to optimize the firing process because it has to be changed with the diffusion process. In this research, we examined the influence of firing conditions on different R{sub sheet} emitters by varying the sheet resistance from 30 to 60 {omega}/sq. The peak temperature and ramp-up rate during the firing process were varied by changing belt speeds and were also varied by changing the temperature settings in different belt furnace zones. As the grid pattern of the front electrode has a significant influence on R{sub s} and FF, we optimized the front grid pattern for each R{sub sheet} emitter. With an increase in the R{sub sheet} of the emitters, V{sub oc} was slightly decreased, as the dopant concentration decreased in the emitter. However, I{sub sc} was increased to a higher degree, which was ascribed to the improvement of blue-response and the reduction of recombination in the front surface. For the same R{sub sheet} of emitters, BSF layers and ohmic contacts were established distinctly at the faster firing condition, which led to a V{sub oc} of around 622 mV and FF of 80.6% by Suns-V{sub oc} measurement. Using the result, we were able to obtain an optimized firing process window for improving V{sub oc} and FF with different R{sub sheet} emitters. These optimized conditions can be applied to the mass production of crystalline Si solar cells. (author)

  3. Effect of drinking water temperature on physiological variables of crossbred dairy cattle at high altitude temperate region of Himalayas

    Directory of Open Access Journals (Sweden)

    D. M. Golher

    2015-10-01

    Full Text Available Aim: The objective of study was to investigate the effects of drinking water on certain physiological parameters such as heart rate (HR, respiration rate (RR, rectal temperature (RT and, ruminal motility (RM. Materials and Methods: The experiment was carried out on 18 farm bred lactating crossbred cows. The animals selected for the study were divided into three groups of six animals each on the basis of milk yield and parity and were allotted to three treatment group of six each such as ambient drinking water temperature at 10.25±0.28°C (ambient water, T1, drinking water temperature at 15-20°C (T2 and drinking water temperature at 35-40°C (T3. All the managemental practices were kept similar during experiment except drinking water temperatures physiological variables such as HR, RR, RT, and RM of the individual cow was measured and recorded twice in a day at 800 h and again at 1400 h two consecutive days in a week 15 min after providing drinking water. Result: HR and RR at morning and at evening recorded were within the normal physiological level for all the treatment groups. However, RT at morning was comparable in all the treatments whereas at evening it was significantly (p<0.01 higher for cows consuming in T2 and in T3 than cows consumed (T1. The RM during morning among the treatments were non-significant as compared to the rumen motility at evening was significantly higher for (T1 and (T2 than for cows in (T3. Conclusion: It can be concluded that offering warm drinking water at 35-40°C to crossbred lactating dairy cow is beneficial during winter at high altitude temperate region.

  4. Chemistry of high temperature superconductors

    CERN Document Server

    1991-01-01

    This review volume contains the most up-to-date articles on the chemical aspects of high temperature oxide superconductors. These articles are written by some of the leading scientists in the field and includes a comprehensive list of references. This is an essential volume for researchers working in the fields of ceramics, materials science and chemistry.

  5. High temperature component life assessment

    CERN Document Server

    Webster, G A

    1994-01-01

    The aim of this book is to investigate and explain the rapid advances in the characterization of high temperature crack growth behaviour which have been made in recent years, with reference to industrial applications. Complicated mathematics has been minimized with the emphasis placed instead on finding solutions using simplified procedures without the need for complex numerical analysis.

  6. Properties of high temperature SQUIDS

    Energy Technology Data Exchange (ETDEWEB)

    Falco, C. M.; Wu, C. T.

    1978-01-01

    A review is given of the present status of weak links and dc and rf biased SQUIDs made with high temperature superconductors. A method for producing reliable, reproducible devices using Nb/sub 3/Sn is outlined, and comments are made on directions future work should take.

  7. High-temperature flooding injury

    Science.gov (United States)

    This problem, also called scald, is most serious in the hot desert valleys of the southwestern United States, subtropical regions in eastern Australia, and western Asia and northern Africa (Middle East) where fields are established and irrigated under high temperatures. The disorder also occurs to...

  8. The effect of maternal and grandmaternal age in benign and high temperature environments

    DEFF Research Database (Denmark)

    Faurby, S; Kjaersgaard, A; Pertoldi, C

    2005-01-01

    Maternal age is known to be of importance for the fitness of the offspring. Few studies have, however, been able to analyse this phenomenon as an isolated effect without confounding effects through genetic variation. This difficulty can be circumvented by working with parthenogenetic organisms. We...... all the traits. Two opposing factors seem to shape the effects of maternal age. Senescence in older mothers leads to a reduction in offspring fitness, whereas, plastic responses lead to more competitive and stress resistant offspring from older mothers. The relative importance of these factors...

  9. Interactive effects of ambient temperature and light sources at high relative humidity on growth performance and blood physiological variables in broilers grown to 42 day of age

    Science.gov (United States)

    The interactive effects of ambient temperature and light sources at high relative humidity on growth performance and blood physiological reactions in broilers grown to 42 day of age were investigated. The experiment consisted of 2 levels (Moderate=21.1, High=26.7 °C) of temperatures and 2 light sour...

  10. High Temperature Superconducting Underground Cable

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, Roger, A.

    2010-02-28

    The purpose of this Project was to design, build, install and demonstrate the technical feasibility of an underground high temperature superconducting (HTS) power cable installed between two utility substations. In the first phase two HTS cables, 320 m and 30 m in length, were constructed using 1st generation BSCCO wire. The two 34.5 kV, 800 Arms, 48 MVA sections were connected together using a superconducting joint in an underground vault. In the second phase the 30 m BSCCO cable was replaced by one constructed with 2nd generation YBCO wire. 2nd generation wire is needed for commercialization because of inherent cost and performance benefits. Primary objectives of the Project were to build and operate an HTS cable system which demonstrates significant progress towards commercial progress and addresses real world utility concerns such as installation, maintenance, reliability and compatibility with the existing grid. Four key technical areas addressed were the HTS cable and terminations (where the cable connects to the grid), cryogenic refrigeration system, underground cable-to-cable joint (needed for replacement of cable sections) and cost-effective 2nd generation HTS wire. This was the world’s first installation and operation of an HTS cable underground, between two utility substations as well as the first to demonstrate a cable-to-cable joint, remote monitoring system and 2nd generation HTS.

  11. High temperature thermoelectric energy conversion

    Science.gov (United States)

    Wood, Charles

    1987-01-01

    The theory and current status of materials research for high-temperature thermoelectric energy conversion are reviewed. Semiconductors are shown to be the preferred class of materials for this application. Optimization of the figure of merit of both broadband and narrow-band semiconductors is discussed as a function of temperature. Phonon scattering mechanisms are discussed, and basic material guidelines are given for reduction of thermal conductivity. Two general classes of materials show promise for high temperature figure of merit (Z) values, namely the rare earth chalcogenides and the boron-rich borides. The electronic transport properties of the rare earth chalcogenides are explicable on the basis of degenerate or partially degenerate n-type semiconductors. Boron and boron-rich borides exhibit p-type hopping conductivity, with detailed explanations proposed for the transport differing from compound to compound. Some discussion is presented on the reasons for the low thermal conductivities in these materials. Also, ZTs greater than one appear to have been realized at high temperature in many of these compounds.

  12. Effects of high temperature frying of Spinach leaves in sunflower oil on carotenoids, chlorophylls and tocopherol composition

    Science.gov (United States)

    Zeb, Alam; Nisar, Parveen

    2017-03-01

    Spinach is one of the highly consumed vegetable, with significant nutritional and beneficial properties. This study revealed for the first time, the effects of high temperature frying on the carotenoids, chlorophylls and tocopherol contents of spinach leaves. Spinach leaves were thermally processed in the sunflower oil for 15, 30, 45 and 60 min at 250 °C. HPLC-DAD results revealed a total of eight carotenoids, four chlorophylls and α-tocopherol in the spinach leaves. Lutein, neoxanthin, violaxanthin and β-carotene-5,6-epoxide were the major carotenoids, while chlorophyll a and b' were present in higher amounts. Frying of spinach leaves increased significantly the amount of α-tocopherol, β-carotene-5,6-epoxide, luteoxanthin, lutein and its Z-isomers and chlorophyll b' isomer. There was a dose dependent decrease in the amounts of neoxanthin, violaxanthin, chlorophyll b, b' and chlorophyll a with increase of frying time. The increase of frying time increased the total phenolic contents in spinach leaves and fried sunflower oil samples. Chemical characteristics such as peroxide values, free fatty acids, conjugated dienes, conjugated trienes and radical scavenging activity were significantly affected by frying, while spinach leaves increased the stability of the frying oil. This study can be used to improve the quality of fried vegetable leaves or their products at high temperature frying in food industries for increasing consumer acceptability.

  13. High temperature, high power piezoelectric composite transducers.

    Science.gov (United States)

    Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, Stewart

    2014-08-08

    Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined.

  14. High temperature effect on microflora of radish root-inhabited zone and nutrient solutions for radish growth

    Science.gov (United States)

    Borodina, E. V.; Tirranen, L. S.

    The effect of high temperatures (35 and 45 °C) on microflora of the root zone of radish plants grown in phytotron was evaluated by the response of microorganisms from 9 indicator groups. Phytotron air temperature elevated to 35 °C for 20 hours caused no significant changes in qualitative and quantitative composition of the root microflora in experimental plants. By the end of the experiment, the species diversity of microflora had changed. The amount of phytopathogenic microorganisms decreased which can be interpreted as more stable co-existence of microflora with plants. The numbers of microbes from other indicator groups was in dynamic equilibrium. The plants' condition did not deteriorate either. Exposure to the temperature of 45 °C for 7 hours have been found to change the numbers and species diversity in the radish root zone microflora. The microorganisms were observed to increase their total numbers at the expense of certain indicator groups. Bacteria increased spore forms at the stage of spores. Colon bacillus bacteria of increased their numbers by the end of experiment by an order. By the end of experiment the roots of experiment plants had microscopic fungi from Mucor, Aspergillus, Trichoderma, Cladosporium genera. The observed changes in the microbial complex seem to be associated with the changes of root emissions and general deterioration of the plants' condition. It is suggested that the response of the microorganisms can be indicative of the condition of plants under investigation.

  15. High Temperature Composite Heat Exchangers

    Science.gov (United States)

    Eckel, Andrew J.; Jaskowiak, Martha H.

    2002-01-01

    High temperature composite heat exchangers are an enabling technology for a number of aeropropulsion applications. They offer the potential for mass reductions of greater than fifty percent over traditional metallics designs and enable vehicle and engine designs. Since they offer the ability to operate at significantly higher operating temperatures, they facilitate operation at reduced coolant flows and make possible temporary uncooled operation in temperature regimes, such as experienced during vehicle reentry, where traditional heat exchangers require coolant flow. This reduction in coolant requirements can translate into enhanced range or system payload. A brief review of the approaches and challengers to exploiting this important technology are presented, along with a status of recent government-funded projects.

  16. Strain effects in high temperature superconductors investigated with magneto-optical imaging

    NARCIS (Netherlands)

    van der Laan, D.C.; van Eck, H.J.N.; van Eck, H.J.N.; ten Haken, Bernard; ten Kate, Herman H.J.; Schwartz, J.

    2003-01-01

    In order to determine the influence of intermediate deformation steps on the mechanical behavior of Bi-based tapes, the effect of longitudinal applied strain is investigated by means of magneto-optical imaging. The strain is applied in a helium flow-cryostat. Cracks appear soon after the critical

  17. Trace element and temperature effects on microbial communities and links to biogas digester performance at high ammonia levels.

    Science.gov (United States)

    Westerholm, Maria; Müller, Bettina; Isaksson, Simon; Schnürer, Anna

    2015-01-01

    High levels of ammonia and the presence of sulphide have major impacts on microbial communities and are known to cause operating problems in anaerobic degradation of protein-rich material. Operating strategies that can improve process performance in such conditions have been reported. The microbiological impacts of these are not fully understood, but their determination could help identify important factors for balanced, efficient operation. This study investigated the correlations between microbial community structure, operating parameters and digester performance in high-ammonia conditions. Continuous anaerobic co-digestion of household waste and albumin was carried out in laboratory-scale digesters at high ammonia concentrations (0.5-0.9 g NH3/L). The digesters operated for 320 days at 37 or 42 °C, with or without addition of a trace element mixture including iron (TE). Abundance and composition of syntrophic acetate-oxidising bacteria (SAOB) and of methanogenic and acetogenic communities were investigated throughout the study using 16S rRNA and functional gene-based molecular methods. Syntrophic acetate oxidation dominated methane formation in all digesters, where a substantial enhancement in digester performance and influence on microbial community by addition of TE was shown dependent on temperature. At 37 °C, TE addition supported dominance and strain richness of Methanoculleus bourgensis and altered the acetogenic community, whereas the same supplementation at 42 °C had a low impact on microbial community structure. Both with and without TE addition operation at 42 °C instead of 37 °C had low impact on digester performance, but considerably restricted acetogenic and methanogenic community structure, evenness and richness. The abundance of known SAOB was higher in digesters without TE addition and in digesters operating at 42 °C. No synergistic effect on digester performance or microbial community structure was observed on combining increased

  18. Effect of high temperatures on cement composite materials in concrete structures

    OpenAIRE

    Bodnárová, L.; Válek, J. (Jan); Sitek, L. (Libor); Foldyna, J.

    2013-01-01

    Concrete is flexible construction materi al, which is utilized in various technologica l applications for underground structures and reinforcement of mine works (adits, tunnels etc.). In such applications, concrete has ma ny functions – static function, water-tightness, gas-tightne ss, resistance to action of aggressive waters as well as durability. In case of railroad and road tunnel constructions, there is an other important problem: influence of high temp eratures on concrete li...

  19. Sequential Elimination of Major-Effect Contributors Identifies Additional Quantitative Trait Loci Conditioning High-Temperature Growth in Yeast

    Science.gov (United States)

    Sinha, Himanshu; David, Lior; Pascon, Renata C.; Clauder-Münster, Sandra; Krishnakumar, Sujatha; Nguyen, Michelle; Shi, Getao; Dean, Jed; Davis, Ronald W.; Oefner, Peter J.; McCusker, John H.; Steinmetz, Lars M.

    2008-01-01

    Several quantitative trait loci (QTL) mapping strategies can successfully identify major-effect loci, but often have poor success detecting loci with minor effects, potentially due to the confounding effects of major loci, epistasis, and limited sample sizes. To overcome such difficulties, we used a targeted backcross mapping strategy that genetically eliminated the effect of a previously identified major QTL underlying high-temperature growth (Htg) in yeast. This strategy facilitated the mapping of three novel QTL contributing to Htg of a clinically derived yeast strain. One QTL, which is linked to the previously identified major-effect QTL, was dissected, and NCS2 was identified as the causative gene. The interaction of the NCS2 QTL with the first major-effect QTL was background dependent, revealing a complex QTL architecture spanning these two linked loci. Such complex architecture suggests that more genes than can be predicted are likely to contribute to quantitative traits. The targeted backcrossing approach overcomes the difficulties posed by sample size, genetic linkage, and epistatic effects and facilitates identification of additional alleles with smaller contributions to complex traits. PMID:18780730

  20. Summary: High Temperature Downhole Motor

    Energy Technology Data Exchange (ETDEWEB)

    Raymond, David W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-10-01

    Directional drilling can be used to enable multi-lateral completions from a single well pad to improve well productivity and decrease environmental impact. Downhole rotation is typically developed with a motor in the Bottom Hole Assembly (BHA) that develops drilling power (speed and torque) necessary to drive rock reduction mechanisms (i.e., the bit) apart from the rotation developed by the surface rig. Historically, wellbore deviation has been introduced by a “bent-sub,” located in the BHA, that introduces a small angular deviation, typically less than 3 degrees, to allow the bit to drill off-axis with orientation of the BHA controlled at the surface. The development of a high temperature downhole motor would allow reliable use of bent subs for geothermal directional drilling. Sandia National Laboratories is pursuing the development of a high temperature motor that will operate on either drilling fluid (water-based mud) or compressed air to enable drilling high temperature, high strength, fractured rock. The project consists of designing a power section based upon geothermal drilling requirements; modeling and analysis of potential solutions; and design, development and testing of prototype hardware to validate the concept. Drilling costs contribute substantially to geothermal electricity production costs. The present development will result in more reliable access to deep, hot geothermal resources and allow preferential wellbore trajectories to be achieved. This will enable development of geothermal wells with multi-lateral completions resulting in improved geothermal resource recovery, decreased environmental impact and enhanced well construction economics.

  1. High temperature two component explosive

    Science.gov (United States)

    Mars, James E.; Poole, Donald R.; Schmidt, Eckart W.; Wang, Charles

    1981-01-01

    A two component, high temperature, thermally stable explosive composition comprises a liquid or low melting oxidizer and a liquid or low melting organic fuel. The oxidizer and fuel in admixture are incapable of substantial spontaneous exothermic reaction at temperatures on the order of 475.degree. K. At temperatures on the order of 475.degree. K., the oxidizer and fuel in admixture have an activation energy of at least about 40 kcal/mol. As a result of the high activation energy, the preferred explosive compositions are nondetonable as solids at ambient temperature, and become detonable only when heated beyond the melting point. Preferable oxidizers are selected from alkali or alkaline earth metal nitrates, nitrites, perchlorates, and/or mixtures thereof. Preferred fuels are organic compounds having polar hydrophilic groups. The most preferred fuels are guanidinium nitrate, acetamide and mixtures of the two. Most preferred oxidizers are eutectic mixtures of lithium nitrate, potassium nitrate and sodium nitrate, of sodium nitrite, sodium nitrate and potassium nitrate, and of potassium nitrate, calcium nitrate and sodium nitrate.

  2. Thermophysical and Mechanical Properties of Granite and Its Effects on Borehole Stability in High Temperature and Three-Dimensional Stress

    Science.gov (United States)

    Bao-lin, Liu; Hai-yan, Zhu; Chuan-liang, Yan; Zhi-jun, Li; Zhi-qiao, Wang

    2014-01-01

    When exploiting the deep resources, the surrounding rock readily undergoes the hole shrinkage, borehole collapse, and loss of circulation under high temperature and high pressure. A series of experiments were conducted to discuss the compressional wave velocity, triaxial strength, and permeability of granite cored from 3500 meters borehole under high temperature and three-dimensional stress. In light of the coupling of temperature, fluid, and stress, we get the thermo-fluid-solid model and governing equation. ANSYS-APDL was also used to stimulate the temperature influence on elastic modulus, Poisson ratio, uniaxial compressive strength, and permeability. In light of the results, we establish a temperature-fluid-stress model to illustrate the granite's stability. The compressional wave velocity and elastic modulus, decrease as the temperature rises, while poisson ratio and permeability of granite increase. The threshold pressure and temperature are 15 MPa and 200°C, respectively. The temperature affects the fracture pressure more than the collapse pressure, but both parameters rise with the increase of temperature. The coupling of thermo-fluid-solid, greatly impacting the borehole stability, proves to be a good method to analyze similar problems of other formations. PMID:24778592

  3. Effects of lead on oxidation behavior of Alloy 690TT within a high temperature aqueous environment

    Science.gov (United States)

    Hou, Qiang; Liu, Zhiyong; Li, Chengtao; Li, Xiaogang

    2017-12-01

    The chemical compositions, phases and structures of two oxide films on Alloy 690TT following exposure for 4400 h in pure water with and without lead at 320 °C were studied by surface analysis techniques. The analysis of a lead-doped oxide film prepared by a focused ion beam (FIB) demonstrated that both Cr-rich and Ni-rich oxides were alternatively distributed within the outer layer, whereas the inner layer was porous and poorly protected, causing severe corrosion of the alloy and a thicker film was formed. A duplex film model was proposed for the effects discussion of lead on the oxidation mechanism.

  4. High temperature structural sandwich panels

    Science.gov (United States)

    Papakonstantinou, Christos G.

    High strength composites are being used for making lightweight structural panels that are being employed in aerospace, naval and automotive structures. Recently, there is renewed interest in use of these panels. The major problem of most commercial available sandwich panels is the fire resistance. A recently developed inorganic matrix is investigated for use in cases where fire and high temperature resistance are necessary. The focus of this dissertation is the development of a fireproof composite structural system. Sandwich panels made with polysialate matrices have an excellent potential for use in applications where exposure to high temperatures or fire is a concern. Commercial available sandwich panels will soften and lose nearly all of their compressive strength temperatures lower than 400°C. This dissertation consists of the state of the art, the experimental investigation and the analytical modeling. The state of the art covers the performance of existing high temperature composites, sandwich panels and reinforced concrete beams strengthened with Fiber Reinforced Polymers (FRP). The experimental part consists of four major components: (i) Development of a fireproof syntactic foam with maximum specific strength, (ii) Development of a lightweight syntactic foam based on polystyrene spheres, (iii) Development of the composite system for the skins. The variables are the skin thickness, modulus of elasticity of skin and high temperature resistance, and (iv) Experimental evaluation of the flexural behavior of sandwich panels. Analytical modeling consists of a model for the flexural behavior of lightweight sandwich panels, and a model for deflection calculations of reinforced concrete beams strengthened with FRP subjected to fatigue loading. The experimental and analytical results show that sandwich panels made with polysialate matrices and ceramic spheres do not lose their load bearing capability during severe fire exposure, where temperatures reach several

  5. High Temperature Heat Exchanger Project

    Energy Technology Data Exchange (ETDEWEB)

    Anthony E. Hechanova, Ph.D.

    2008-09-30

    The UNLV Research Foundation assembled a research consortium for high temperature heat exchanger design and materials compatibility and performance comprised of university and private industry partners under the auspices of the US DOE-NE Nuclear Hydrogen Initiative in October 2003. The objectives of the consortium were to conduct investigations of candidate materials for high temperature heat exchanger componets in hydrogen production processes and design and perform prototypical testing of heat exchangers. The initial research of the consortium focused on the intermediate heat exchanger (located between the nuclear reactor and hydrogen production plan) and the components for the hydrogen iodine decomposition process and sulfuric acid decomposition process. These heat exchanger components were deemed the most challenging from a materials performance and compatibility perspective

  6. Motor for High Temperature Applications

    Science.gov (United States)

    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.

  7. Effect of aluminumion implantation on high temperature oxidation of nickel-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mitsuo, Atsushi (Tokyo Metropolitan Industrial Technology Center, 3-13-10 Nishigaoka, Kita-ku, Tokyo 115 (Japan)); Tanaki, Toshiyuki (Tokyo Metropolitan Industrial Technology Center, 3-13-10 Nishigaoka, Kita-ku, Tokyo 115 (Japan)); Shinozaki, Teruo (Japan Gas Appliances Inspection Association, 4-1-10 Azusawa, Itabashi-ku, Tokyo 174 (Japan)); Iwaki, Masaya (Institute of Physics and Chemical Research, 2-1 Hirosawa, Wako-shi, Saitama 350-01 (Japan))

    1994-08-01

    The thermal oxidation properties of Al-ion-implanted, Ni-based alloys used for thermocouples of Inconel 600, alumel, chromel and constantan have been studied in humid O[sub 2] atmospheres at 970K for 50h. The Al ion implantation was performed with doses ranging from 1x10[sup 16] to 2x10[sup 17] ioncm[sup -2] at an energy of 50keV. The depth profiles measured by Auger electron spectroscopy showed that the concentrations of Al and O were higher near the surface of the alloys after implantation. The implanted alumel and constantan exhibited no effect on the suppression of oxidation. However, implantation above a dose of 1x10[sup 17]Al ioncm[sup -2] significantly slowed the oxidation of the Inconel 600 and chromel alloys containing Cr. The thermoelectric properties of the actual thermocouples modified by Al ion implantation are discussed. ((orig.))

  8. Optimisation of the microporous layer for a polybenzimidazole-based high temperature PEMFC - effect of carbon content

    Energy Technology Data Exchange (ETDEWEB)

    Lobato, J.; Canizares, P.; Rodrigo, M.A.; Ubeda, D.; Pinar, F.J.; Linares, J.J. [Department of Chemical Engineering, University of Castilla-La Mancha, Av. Camilo Jose Cela, n 12. 13071, Ciudad Real (Spain)

    2010-10-15

    This work aims at studying the role of the microporous layer (MPL) in electrodes prepared for high temperature PBI-based PEMFC. The two main components of this layer are carbon black and a polymeric binder (Teflon). This work addresses the effect of the MPL carbon amount on the performance of a high temperature PEMFC. Thus, gas diffusion layers (GDLs) containing MPL with different carbon contents (from 0.5 to 4 mg cm{sup -2}) were prepared. Firstly, they were physically characterised by Hg-porosimetry measuring pore size distribution, porosity, tortuosity and mean pore size. Permeability measurements were also performed. The higher the carbon content was the lower both porosity and permeability were. Afterwards, electrodes were prepared with these GDLs and were electrochemically characterised. Electrochemical surface area (ESA) was determined and fuel cell performance was evaluated under different fuel and comburent stoichiometries, supporting these results with impedance spectra. This made it possible to see the benefits of the MPL inclusion in the electrode structure, with a significant increase in the fuel cell performance and ESA. Once the goodness of the MPL was confirmed, result analysis led to an optimum MPL composition of 2 mg cm{sup -2} of carbon for both electrodes, anode and cathode. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  9. Very High Temperature Sound Absorption Coating Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Phase I demonstrated experimentally a very high temperature acoustically absorbing coating for ducted acoustics applications. High temperature survivability at 3500...

  10. The Interaction Effect of Salicylic Acid and High Temperature Stress on Some Physiological Characteristics of Maize Zea mays L.(

    Directory of Open Access Journals (Sweden)

    M Attarzadeh

    2015-04-01

    Full Text Available The present study was conducted to evaluate the effects of salicylic acid and High temperature on physiological characteristics of maize (cv. SC704. In order to, a factorial experiment based on randomized complete blocks design with three replications was carried out in Research Greenhouse of Vali-e-Asr University of Rafsanjan. The factors were included pre-treatment of concentrations of salicylic acid (0, 50, 100 and 200 μM and duration of 40°C (0, 8, 16 and 24 hours. Results showed that SPAD index increased significantly in levels of 50 and 100μM salicylic acid but it was low in control and 200μM salicylic acid. In level of 50μM salicylic acid, increase in duration of heat stress was resulted in increasing content of a and ab chlorophyll. However, it was occurred conversely in level of 200 μM salicylic acid, i.e., content of a and ab was decreased. Levels of salicylic acid and duration of heat stress did not effect on Fv/Fm and content of soluble sugar. Use of 200 μM salicylic acid decreased significantly relative water content, while increase in duration of heat stress caused to increase relative water content. In addition, increase in duration of heat stress resulted in increasing leaf temperature and proline content.

  11. Effect of Tube Arrangement on the Thermal Performance of a High Temperature Generator of the Absorption System

    Science.gov (United States)

    Lee, Insong; Cho, Keumnam

    The present study numerically investigated the effect of tube arrangement on the thermal performance of the high temperature generator (HTG) of a double effect LiBr-water absorption system with the cooling capacity of 210 refrigeration tons. The HTG tubes were located behind the pre-mixed surface flame burner. The HTG was consisted with a set of circular tubes and flattened tubes in series. LiBr aqueous weak solution was flowed into the HTG tube, and then turned to strong solution at the exit of the HTG tube. FLUENT, as a commercial code, was used to estimate the thermal performance of the HTG. Standard k-ɛ model was applied for the turbulent flow of combustion gas around the HTG tubes. Key parameters were the diameter of the circular tube and tube pitch ratio of flattened and circular tubes in the HTG. The combustion gas temperature was increased and its heat transfer rate was decreased as the circular tube diameter was increased, and the pitch ratios of both circular and flattened were decreased.

  12. Nanoscale high-temperature superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, P.; Wei, J.Y.T.; Ananth, V.; Morales, P.; Skocpol, W

    2004-08-01

    We discuss the exciting prospects of studying high-temperature superconductivity in the nanometer scale from the perspective of experiments, theory and simulation. In addition to enabling studies of novel quantum phases in an unexplored regime of system dimensions and parameters, nanoscale high-temperature superconducting structures will allow exploration of fundamental mechanisms with unprecedented insight. The prospects include, spin-charge separation, detection of electron fractionalization via novel excitations such as vison, stripe states and their dynamics, preformed cooper pairs or bose-condensation in the underdoped regime, and other quantum-ordered states. Towards this initiative, we present the successful development of a novel nanofabrication technique for the epitaxial growth of nanoscale cuprates. Combining the techniques of e-beam lithography and nanomachining, we have been able to fabricate the first generation of high-temperature superconducting nanoscale devices, including Y-junctions, four-probe wires and rings. Their initial transport characterization and scanning tunneling microscopy reveal the integrity of the crystal structure, grown on nanometer scale lateral dimensions. Here, we present atomic force micrographs and electrical characterization of a few nanoscale YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) samples.

  13. [Mechanism of dwarfing effect of tomato (Solanum lycopersicon) seedlings induced by cold-shock treatment under high temperature stress].

    Science.gov (United States)

    Li, Sheng-li; Bi, Ming-ming; Chen, Fei; Sun, Zhi-qiang

    2015-07-01

    To explore the dwarfing mechanism of tomato seedlings induced by cold-shock treatment followed by high temperature, tomato seedlings were subjected to cold-shock treatment once a day at 8:00 with temperature of 5, 10 and 15 °C for 10, 20 and 30 min, respectively, and ethylene production rate was measured. Plant height, ethylene production and gibberellin (GA3) content of the seedlings treated with T10 °C D10 min (cold-shock with 10 °C for 10 min), coupled with utilization of growth regulators, were also evaluated. The results showed that the release of ethylene was increased with the decrease of cold-shock temperature and extension of treatment time. The cold-shock treatment of 5 °C and 30 min had the highest ethylene production rate of 60.3 nL h-1 . g-1, which was 6.5 times of the control. None of ethephon (ETH), silver thiosulphate (STS), GA, or paclobutrazol (PP333) could completely block high ethylene production induced by cold-shock treatment. Tomato seedlings with cold-shock treatment (T10 °C D10 min ) resulted in reduction in GA3 content by 38.1% compared with the value of control (130.6 µg . g-1). Neither ethephon nor STS had significant effect on the dwarfing induced by cold-shock. However, GA3 weakened the dwarfing effect induced by cold-shock treatment (T10 °C D10 min), while PP333 greatly enhanced it. The dwarfing effect by cold-shock treatment of T10 °C D10 min was equivalent to that of application of 4.0 mg . L-1 PP333 based on the seedling height as an evaluation indicator. It was concluded that cold-shock treatment stimulated shoot ethylene production and blocked GA3 synthesis. GA3 played a vital role in dwarfing effect on tomato seedling induced by cold-shock treatment. Cold-shock with 10 °C and duration of 10 min could promote the growth of tomato seedlings with shorter stem and higher dry mass accumulation.

  14. Effects of Alloying Elements on Room and High Temperature Tensile Properties of Al-Si Cu-Mg Base Alloys =

    Science.gov (United States)

    Alyaldin, Loay

    In recent years, aluminum and aluminum alloys have been widely used in automotive and aerospace industries. Among the most commonly used cast aluminum alloys are those belonging to the Al-Si system. Due to their mechanical properties, light weight, excellent castability and corrosion resistance, these alloys are primarily used in engineering and in automotive applications. The more aluminum is used in the production of a vehicle, the less the weight of the vehicle, and the less fuel it consumes, thereby reducing the amount of harmful emissions into the atmosphere. The principal alloying elements in Al-Si alloys, in addition to silicon, are magnesium and copper which, through the formation of Al2Cu and Mg2Si precipitates, improve the alloy strength via precipitation hardening following heat treatment. However, most Al-Si alloys are not suitable for high temperature applications because their tensile and fatigue strengths are not as high as desired in the temperature range 230-350°C, which are the temperatures that are often attained in automotive engine components under actual service conditions. The main challenge lies in the fact that the strength of heat-treatable cast aluminum alloys decreases at temperatures above 200°C. The strength of alloys under high temperature conditions is improved by obtaining a microstructure containing thermally stable and coarsening-resistant intermetallics, which may be achieved with the addition of Ni. Zr and Sc. Nickel leads to the formation of nickel aluminide Al3Ni and Al 9FeNi in the presence of iron, while zirconium forms Al3Zr. These intermetallics improve the high temperature strength of Al-Si alloys. Some interesting improvements have been achieved by modifying the composition of the base alloy with additions of Mn, resulting in an increase in strength and ductility at both room and high temperatures. Al-Si-Cu-Mg alloys such as the 354 (Al-9wt%Si-1.8wt%Cu-0.5wt%Mg) alloys show a greater response to heat treatment as a

  15. Spectroscopic Study of Solvation Properties of Room-Temperature Ionic Liquids and Solvent Effect on Bimolecular Fluorescence Quenching Reaction at High Pressures

    National Research Council Canada - National Science Library

    KOMETANI, Noritsugu; MINAMIKAWA, Yoshinori

    2013-01-01

      The solvation properties of some room-temperature ionic liquids (RTILs) and the solvent effect on bimolecular fluorescence quenching reaction have been examined at high pressures ranging from 0.1 to 300 MPa...

  16. Changes in leaf epicuticular wax load and its effect on leaf temperature and physiological traits in wheat cultivars (Triticum aestivum L.) exposed to high temperatures during anthesis

    Science.gov (United States)

    The physiological functions of epicuticular wax (EW) include reflectance of irradiation and the reduction of water loss. When a plant experiences stressful conditions, most notably, high irradiance and temperature, damage to the photosynthetic apparatus can occur and is signaled by a decrease in the...

  17. Growth anisotropy effect of bulk high temperature superconductors on the levitation performance in the applied magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, J., E-mail: jzheng@swjtu.edu.cn; Liao, X.L.; Jing, H.L.; Deng, Z.G.; Yen, F.; Wang, S.Y.; Wang, J.S.

    2013-10-15

    Highlights: • The single-layer bulk HTSC with AGSBP obtains better levitation performance than that of MGSBP. • The double-layer bulk with AGSBP obtains better levitation performance than that of MGSBP too. • The double-layer bulk finding is contrast to MGSBP if pursuing high trapped field. • The optimization is highlighted by simple and easy operation, thus economical in the practice. -- Abstract: Growth anisotropies of bulk high temperature superconductors (HTSCs) fabricated by a top-seeded melt texture growth process, that is, different pinning effect in the growth sectors (GSs) and growth sector boundaries (GSBs), possess effect on the macro flux trapping and levitation performance of bulk HTSCs. Previous work (Physics Procedia, 36 (2012) 1043) has found that the bulk HTSC array with aligned GSB pattern (AGSBP) exhibits better capability for levitation and suppression of levitation force decay above a permanent magnet guideway (PMG) compared with misaligned GSB pattern (MGSBP). In this paper, we further examine this growth anisotropy effect on the maglev performance of a double-layer bulk HTSC. In contrast to reported trapped flux cases (Supercond. Sci. Technol. 19 (2006) S466), the two superposed bulk HTSCs with same AGSBP with PMG are found to show better maglev performance. These series of results are helpful and support a new way for the performance optimization of present HTS maglev systems.

  18. High temperature PEM fuel cells

    Science.gov (United States)

    Zhang, Jianlu; Xie, Zhong; Zhang, Jiujun; Tang, Yanghua; Song, Chaojie; Navessin, Titichai; Shi, Zhiqing; Song, Datong; Wang, Haijiang; Wilkinson, David P.; Liu, Zhong-Sheng; Holdcroft, Steven

    There are several compelling technological and commercial reasons for operating H 2/air PEM fuel cells at temperatures above 100 °C. Rates of electrochemical kinetics are enhanced, water management and cooling is simplified, useful waste heat can be recovered, and lower quality reformed hydrogen may be used as the fuel. This review paper provides a concise review of high temperature PEM fuel cells (HT-PEMFCs) from the perspective of HT-specific materials, designs, and testing/diagnostics. The review describes the motivation for HT-PEMFC development, the technology gaps, and recent advances. HT-membrane development accounts for ∼90% of the published research in the field of HT-PEMFCs. Despite this, the status of membrane development for high temperature/low humidity operation is less than satisfactory. A weakness in the development of HT-PEMFC technology is the deficiency in HT-specific fuel cell architectures, test station designs, and testing protocols, and an understanding of the underlying fundamental principles behind these areas. The development of HT-specific PEMFC designs is of key importance that may help mitigate issues of membrane dehydration and MEA degradation.

  19. Temperature uniformity mapping in a high pressure high temperature reactor using a temperature sensitive indicator

    NARCIS (Netherlands)

    Grauwet, T.; Plancken, van der I.; Vervoort, L.; Matser, A.M.; Hendrickx, M.; Loey, van A.

    2011-01-01

    Recently, the first prototype ovomucoid-based pressure–temperature–time indicator (pTTI) for high pressure high temperature (HPHT) processing was described. However, for temperature uniformity mapping of high pressure (HP) vessels under HPHT sterilization conditions, this prototype needs to be

  20. Distinct Effects of Abelson Kinase Mutations on Myocytes and Neurons in Dissociated Drosophila Embryonic Cultures: Mimicking of High Temperature

    Science.gov (United States)

    Liu, Lijuan; Wu, Chun-Fang

    2014-01-01

    Abelson tyrosine kinase (Abl) is known to regulate axon guidance, muscle development, and cell-cell interaction in vivo. The Drosophila primary culture system offers advantages in exploring the cellular mechanisms mediated by Abl with utilizing various experimental manipulations. Here we demonstrate that single-embryo cultures exhibit stage-dependent characteristics of cellular differentiation and developmental progression in neurons and myocytes, as well as nerve-muscle contacts. In particular, muscle development critically depends on the stage of dissociated embryos. In wild-type (WT) cultures derived from embryos before stage 12, muscle cells remained within cell clusters and were rarely detected. Interestingly, abundant myocytes were spotted in Abl mutant cultures, exhibiting enhanced myocyte movement and fusion, as well as neuron-muscle contacts even in cultures dissociated from younger, stage 10 embryos. Notably, Abl myocytes frequently displayed well-expanded lamellipodia. Conversely, Abl neurons were characterized with fewer large veil-like lamellipodia, but instead had increased numbers of filopodia and darker nodes along neurites. These distinct phenotypes were equally evident in both homo- and hetero-zygous cultures (Abl/Abl vs. Abl/+) of different alleles (Abl1 and Abl4) indicating dominant mutational effects. Strikingly, in WT cultures derived from stage 10 embryos, high temperature (HT) incubation promoted muscle migration and fusion, partially mimicking the advanced muscle development typical of Abl cultures. However, HT enhanced neuronal growth with increased numbers of enlarged lamellipodia, distinct from the characteristic Abl neuronal morphology. Intriguingly, HT incubation also promoted Abl lamellipodia expansion, with a much greater effect on nerve cells than muscle. Our results suggest that Abl is an essential regulator for myocyte and neuron development and that high-temperature incubation partially mimics the faster muscle development

  1. Effect of moderate inlet temperatures in ultra-high-pressure homogenization treatments on physicochemical and sensory characteristics of milk.

    Science.gov (United States)

    Amador-Espejo, G G; Suàrez-Berencia, A; Juan, B; Bárcenas, M E; Trujillo, A J

    2014-02-01

    The effect of ultra-high-pressure homogenization (UHPH) on raw whole milk (3.5% fat) was evaluated to obtain processing conditions for the sterilization of milk. Ultra-high-pressure homogenization treatments of 200 and 300 MPa at inlet temperatures (Ti) of 55, 65, 75, and 85 °C were compared with a UHT treatment (138 °C for 4s) in terms of microbial inactivation, particle size and microstructure, viscosity, color, buffering capacity, ethanol stability, propensity to proteolysis, and sensory evaluation. The UHPH-treated milks presented a high level of microbial reduction, under the detection limit, for treatments at 300 MPa with Ti of 55, 65, 75, and 85 °C, and at 200 MPa with Ti = 85 °C, and few survivors in milks treated at 200 MPa with Ti of 55, 65, and 75 °C. Furthermore, UHPH treatments performed at 300 MPa with Ti = 75 and 85 °C produced sterile milk after sample incubation (30 and 45 °C), obtaining similar or better characteristics than UHT milk in color, particle size, viscosity, buffer capacity, ethanol stability, propensity to protein hydrolysis, and lower scores in sensory evaluation for cooked flavor. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  2. Effects of Lignocellulosic Compounds on the Yield, Nanostructure and Reactivity of Soot from Fast Pyrolysis at High Temperatures

    DEFF Research Database (Denmark)

    Trubetskaya, Anna; Broström, Markus; Kling, Jens

    Gasification offers the utilization of biomass to a wide variety of applications such as heat, electricity, chemicals and transport fuels in an efficient and sustainable manner. High soot yields in the high-temperature entrained flow gasification lead to intensive gas cleaning and can cause...... reactor. The specific objectives of this study were to: (1) obtain knowledge about lignocellulosic compounds and monolignols influence on the yield, nanostructure, composition, and reactivity of soot during high-temperature gasification, (2) understand the influence of Soxhlet extraction on the soot...... reactivity and characteristics, and (3) determine the reaction conditions and fuel composition which minimize soot formation leading to the efficient operation of high-temperature gasification process....

  3. [Effects of cold-shock on the growth and flower bud differentiation of tomato seedlings under high temperature stress].

    Science.gov (United States)

    Li, Sheng-li; Xia, Ya-zhen; Sun, Zhi-qiang

    2016-02-01

    In order to explore the effects of cold-shock on the growth and flower bud differentiation of tomato seedlings under high temperature, tomato seedlings were subjected to cold-shock treat- ments every day with 10 °C for 10 minutes in. an artificial climate chamber. Tomato seedlings were treated with cold-shock at the first true leaf stage and the treatment lasted for 15 days. Tomato seed- lings without cold-shock were used as control. At the fourth true leaf period of tomato seedlings, five plants were randomly sampled and the growth characteristics and the ultrastructure changes of meso- phyll cell of tomato seedlings were examined. The flower bud differentiation process of tomato seed- lings was observed at the periods of the second, fourth and sixth true leaves respectively. Flowering and fruiting of tomato seedlings were also investigated after transplanting. The results showed that the stem diameter and health index of tomato seedlings with cold-shock were enhanced by 7.2% and 55.5% compared with seedlings without cold-shock. Mesophyll cells of the seedlings with cold-shock arranged loosely and various organelles such as chloroplasts and mitochondria were morphologically integrated, while chloroplasts and mitochondria of seedlings mesophyll cells without cold-shock swelled up and thylakoids vacuolized apparently. The flower bud differentiation process of seedlings with cold-shock could be advanced significantly at the early seedling stage compared with the control and the advancement was weakened with the seedling growing. Fruit set number and percentage on the first and second inflorescence of tomato plants transplanted by seedlings with cold-shock were enhanced significantly compared with those of the control. These results indicated that the injury of membrane structure of various organelles, especially chloroplast and mitochondria could be allevia- ted by cold-shock treatment under high temperature tress. Cold-shock treatment could not only im- prove the

  4. Effects of pre-irradiation annealing at high temperature on optical absorption and electron paramagnetic resonance of natural pumpellyite mineral

    Energy Technology Data Exchange (ETDEWEB)

    Javier-Ccallata, Henry, E-mail: henrysjc@gmail.com [Escuela de Ingeniería Electrónica y Telecomunicaciones, Universidad Alas Peruanas Filial Arequipa, Urb. D. A. Carrión G-14, J. L. Bustamante y Rivero, Arequipa (Peru); Laboratório de Sistemas Nanoestruturados, Departamento de Física, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina (Brazil); Filho, Luiz Tomaz [Departamento de Física Nuclear, Instituto de Física, Universidade de São Paulo, Rua do Matão, travessa R, 187, CEP 05508-900 São Paulo, SP (Brazil); Faculdade de Tecnologia e Ciências Exatas, Universidade São Judas Tadeu, Rua Taquari 546, São Paulo, SP (Brazil); Sartorelli, Maria L. [Laboratório de Sistemas Nanoestruturados, Departamento de Física, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina (Brazil); Watanabe, Shigueo [Departamento de Física Nuclear, Instituto de Física, Universidade de São Paulo, Rua do Matão, travessa R, 187, CEP 05508-900 São Paulo, SP (Brazil)

    2013-09-15

    Highlights: •Natural pumpellyite mineral presents superposition bands around 900 and 1060 nm due Fe{sup 2+}and Fe{sup 3+}. •High temperature annealing influences the EPR and OA spectra. •The behavior of EPR line for 800 and 900 °C can be attributed to forbidden dd transitions due the Fe{sup 3+}. -- Abstract: Natural silicate mineral of pumpellyite, Ca{sub 2}MgAl{sub 2}(SiO{sub 4})(Si{sub 2}O{sub 7})(OH){sub 2}·(H{sub 2}O), point group A2/m, has been studied concerning high temperature annealing and γ-radiation effects on Optical Absorption (OA) and Electron Paramagnetic Resonance (EPR) properties. Chemical analysis revealed that besides Si, Al, Ca and Mg, other oxides i.e., Fe, Mn, Na, K, Ti and P are present in the structure as impurities. OA measurements of natural and annealed pumpellyite revealed several bands in the visible region due to spin forbidden transitions of Fe{sup 2+} and Fe{sup 3+}. The behaviour of bands around 900 and 1060 nm, with pre-annealing and γ radiation dose, indicating a transition Fe{sup 2+} → e{sup −} + Fe{sup 3+}. On the other hand, EPR measurements reveal six lines of Mn{sup 2+}, and satellites due to hyperfine interaction, superimposed on the signal of Fe{sup 3+} around of g = 2. For heat treatment from 800 °C the signal grows significantly and for 900 °C a strong signal of Fe{sup 3+} hides all Mn{sup 2+} lines. The strong growth of this signal indicates that the transitions are due to Fe{sup 3+} dipole–dipole interactions.

  5. Oxidation and the Effects of High Temperature Exposures on Notched Fatigue Life of an Advanced Powder Metallurgy Disk Superalloy

    Science.gov (United States)

    Sudbrack, Chantal K.; Draper, Susan L.; Gorman, Timothy T.; Telesman, Jack; Gab, Timothy P.; Hull, David R.

    2012-01-01

    Oxidation and the effects of high temperature exposures on notched fatigue life were considered for a powder metallurgy processed supersolvus heat-treated ME3 disk superalloy. The isothermal static oxidation response at 704 C, 760 C, and 815 C was consistent with other chromia forming nickel-based superalloys: a TiO2-Cr2O3 external oxide formed with a branched Al2O3 internal subscale that extended into a recrystallized - dissolution layer. These surface changes can potentially impact disk durability, making layer growth rates important. Growth of the external scales and dissolution layers followed a cubic rate law, while Al2O3 subscales followed a parabolic rate law. Cr- rich M23C6 carbides at the grain boundaries dissolved to help sustain Cr2O3 growth to depths about 12 times thicker than the scale. The effect of prior exposures was examined through notched low cycle fatigue tests performed to failure in air at 704 C. Prior exposures led to pronounced debits of up to 99 % in fatigue life, where fatigue life decreased inversely with exposure time. Exposures that produced roughly equivalent 1 m thick external scales at the various isotherms showed statistically equivalent fatigue lives, establishing that surface damage drives fatigue debit, not exposure temperature. Fractographic evaluation indicated the failure mode for the pre-exposed specimens involved surface crack initiations that shifted with exposure from predominately single intergranular initiations with transgranular propagation to multi-initiations from the cracked external oxide with intergranular propagation. Weakened grain boundaries at the surface resulting from the M23C6 carbide dissolution are partially responsible for the intergranular cracking. Removing the scale and subscale while leaving a layer where M23C6 carbides were dissolved did not lead to a significant fatigue life improvement, however, also removing the M23C6 carbide dissolution layer led to nearly full recovery of life, with a

  6. Effects of Medium Temperature and Industrial By-Products on the Key Hardened Properties of High Performance Concrete.

    Science.gov (United States)

    Safiuddin, Md; Raman, Sudharshan N; Zain, Muhammad Fauzi Mohd

    2015-12-10

    The aim of the work reported in this article was to investigate the effects of medium temperature and industrial by-products on the key hardened properties of high performance concrete. Four concrete mixes were prepared based on a water-to-binder ratio of 0.35. Two industrial by-products, silica fume and Class F fly ash, were used separately and together with normal portland cement to produce three concrete mixes in addition to the control mix. The properties of both fresh and hardened concretes were examined in the laboratory. The freshly mixed concrete mixes were tested for slump, slump flow, and V-funnel flow. The hardened concretes were tested for compressive strength and dynamic modulus of elasticity after exposing to 20, 35 and 50 °C. In addition, the initial surface absorption and the rate of moisture movement into the concretes were determined at 20 °C. The performance of the concretes in the fresh state was excellent due to their superior deformability and good segregation resistance. In their hardened state, the highest levels of compressive strength and dynamic modulus of elasticity were produced by silica fume concrete. In addition, silica fume concrete showed the lowest level of initial surface absorption and the lowest rate of moisture movement into the interior of concrete. In comparison, the compressive strength, dynamic modulus of elasticity, initial surface absorption, and moisture movement rate of silica fume-fly ash concrete were close to those of silica fume concrete. Moreover, all concretes provided relatively low compressive strength and dynamic modulus of elasticity when they were exposed to 50 °C. However, the effect of increased temperature was less detrimental for silica fume and silica fume-fly ash concretes in comparison with the control concrete.

  7. High temperature annealing effects on deep-level defects in a high purity semi-insulating 4H-SiC substrate

    Science.gov (United States)

    Iwamoto, Naoya; Azarov, Alexander; Ohshima, Takeshi; Moe, Anne Marie M.; Svensson, Bengt G.

    2015-07-01

    Effects of high-temperature annealing on deep-level defects in a high-purity semi-insulating 4H silicon carbide substrate have been studied by employing current-voltage, capacitance-voltage, junction spectroscopy, and chemical impurity analysis measurements. Secondary ion mass spectrometry data reveal that the substrate contains boron with concentration in the mid 1015 cm-3 range, while other impurities including nitrogen, aluminum, titanium, vanadium and chromium are below their detection limits (typically ˜1014 cm-3). Schottky barrier diodes fabricated on substrates annealed at 1400-1700 °C exhibit metal/p-type semiconductor behavior with a current rectification of up to 8 orders of magnitude at bias voltages of ±3 V. With increasing annealing temperature, the series resistance of the Schottky barrier diodes decreases, and the net acceptor concentration in the substrates increases approaching the chemical boron content. Admittance spectroscopy results unveil the presence of shallow boron acceptors and deep-level defects with levels in lower half of the bandgap. After the 1400 °C annealing, the boron acceptor still remains strongly compensated at room temperature by deep donor-like levels located close to mid-gap. However, the latter decrease in concentration with increasing annealing temperature and after 1700 °C, the boron acceptor is essentially uncompensated. Hence, the deep donors are decisive for the semi-insulating properties of the substrates, and their thermal evolution limits the thermal budget for device processing. The origin of the deep donors is not well-established, but substantial evidence supporting an assignment to carbon vacancies is presented.

  8. High Temperature Fatigue Life Evaluation Using Small Specimen

    National Research Council Canada - National Science Library

    NOGAMI, Shuhei; HISAKA, Chiaki; FUJIWARA, Masaharu; WAKAI, Eichi; HASEGAWA, Akira

    2017-01-01

    For developing the high temperature fatigue life evaluation method using small specimen, the effect of specimen size and test environment on the high temperature fatigue life of the reduced activation...

  9. High Temperature Radio Frequency Loads

    CERN Document Server

    Federmann, S; Grudiev, A; Montesinos, E; Syratchev, I

    2011-01-01

    In the context of energy saving and recovery requirements the design of reliable and robust RF power loads which permit a high outlet temperature and high pressure of the cooling water is desirable. Cooling water arriving at the outlet withmore than 150 ◦C and high pressure has a higher value than water with 50 ◦C under low pressure. Conventional RF power loads containing dielectric and magnetic materials as well as sensitive ceramic windows usually do not permit going much higher than 90 ◦C. Here we present and discuss several design concepts for "metal only" RF high power loads. One concept is the application of magnetic steel corrugated waveguides near cutoff – this concept could find practical use above several GHz. Another solution are resonant structures made of steel to be installed in large waveguides for frequencies of 500 MHz or lower. Similar resonant structures above 100 MHz taking advantage of the rather high losses of normal steel may also be used in coaxial line geometries with large di...

  10. The Effect of Increasing Sn Content on High-Temperature Mechanical Deformation of an Mg-3%Cu-1%Ca Alloy

    Directory of Open Access Journals (Sweden)

    Georgios S.E. Antipas

    2013-11-01

    Full Text Available Chill casting of magnesium alloy samples with secondary alloying elements of Cu, Ca and Sn at % w.t. concentrations in the range 1–5, 0.1–5 and 0.1–3 respectively, gave rise to appreciably enhanced resistance to high-temperature creep, while maintaining good heat conductivity. The latter was considered to be driven by Cu and Mg-Cu intermetallics while it was clear that Sn mediated the high-temperature performance, mainly via networks of Mg2Sn and MgCaSn precipitates along the Mg matrix grain boundaries. It was postulated that Sn formed intermetallics by preferential substitution of Ca atoms and, thus, did not degrade the heat conductivity by retaining Cu. The % w.t. stoichiometry with the optimum combination of heat conductivity and resistance to high-temperature creep was found to be Mg-3Cu-1Ca-0.1Sn.

  11. Complex performance during exposure to high temperatures.

    Science.gov (United States)

    1969-06-01

    The effects of high temperature on psychomotor performance and physiological function were studied on male pilots (age 30-51) holding a current medical certificate. A total of 41 runs were made at neutral (23.8C (75F), or hot (60.0C (140F), 71.1C (16...

  12. High pressure and high temperature behaviour of ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Thakar, Nilesh A. [K. K. Shah Jarodwala Maninagar Science College, Rambaug, Maninagar, Ahmedabad-380008 (India); Bhatt, Apoorva D. [Department of Physics, Gujarat University, Ahmedabad-380009 (India); Pandya, Tushar C., E-mail: pandyatc@gmail.com [St. Xavier' s College, Navrangpura, Ahmedabad-380009 (India)

    2014-04-24

    The thermodynamic properties with the wurtzite (B4) and rocksalt (B1) phases of ZnO under high pressures and high temperatures have been investigated using Tait's Equation of state (EOS). The effects of pressures and temperatures on thermodynamic properties such as bulk modulus, thermal expansivity and thermal pressure are explored for both two structures. It is found that ZnO material gradually softens with increase of temperature while it hardens with the increment of the pressure. Our predicted results of thermodynamics properties for both the phases of ZnO are in overall agreement with the available data in the literature.

  13. Characterization of Different Capsicum Varieties by Evaluation of Their Capsaicinoids Content by High Performance Liquid Chromatography, Determination of Pungency and Effect of High Temperature

    Directory of Open Access Journals (Sweden)

    Alberto González-Zamora

    2013-10-01

    Full Text Available The chili pepper is a very important plant used worldwide as a vegetable, as a spice, and as an external medicine. In this work, eight different varieties of Capsicum annuum L. have been characterized by their capsaicinoids content. The chili pepper fruits were cultivated in the Comarca Lagunera region in North of Mexico. The qualitative and quantitative determination of the major and minor capsaicinoids; alkaloids responsible for the pungency level, has been performed by a validated chromatographic procedure (HPLC-DAD after a preliminary drying step and an opportune extraction procedure. Concentrations of total capsaicinoids varied from a not detectable value for Bell pepper to 31.84 mg g−1 dried weight for Chiltepín. Samples were obtained from plants grown in experimental field and in greenhouse without temperature control, in order to evaluate temperature effect. Analysis of the two principal capsaicinoids in fruits showed that the amount of dihydrocapsaicin was always higher than capsaicin. In addition, our results showed that the content of total capsaicinoids for the varieties Serrano, Puya, Ancho, Guajillo and Bell pepper were increased with high temperature, while the content of total capsaicinoids and Scoville heat units (SHU for the varieties De árbol and Jalapeño decreased. However, the pungency values found in this study were higher for all varieties analyzed than in other studies.

  14. Characterization of different Capsicum varieties by evaluation of their capsaicinoids content by high performance liquid chromatography, determination of pungency and effect of high temperature.

    Science.gov (United States)

    González-Zamora, Alberto; Sierra-Campos, Erick; Luna-Ortega, J Guadalupe; Pérez-Morales, Rebeca; Rodríguez Ortiz, Juan Carlos; García-Hernández, José L

    2013-10-31

    The chili pepper is a very important plant used worldwide as a vegetable, as a spice, and as an external medicine. In this work, eight different varieties of Capsicum annuum L. have been characterized by their capsaicinoids content. The chili pepper fruits were cultivated in the Comarca Lagunera region in North of Mexico. The qualitative and quantitative determination of the major and minor capsaicinoids; alkaloids responsible for the pungency level, has been performed by a validated chromatographic procedure (HPLC-DAD) after a preliminary drying step and an opportune extraction procedure. Concentrations of total capsaicinoids varied from a not detectable value for Bell pepper to 31.84 mg g(-1) dried weight for Chiltepín. Samples were obtained from plants grown in experimental field and in greenhouse without temperature control, in order to evaluate temperature effect. Analysis of the two principal capsaicinoids in fruits showed that the amount of dihydrocapsaicin was always higher than capsaicin. In addition, our results showed that the content of total capsaicinoids for the varieties Serrano, Puya, Ancho, Guajillo and Bell pepper were increased with high temperature, while the content of total capsaicinoids and Scoville heat units (SHU) for the varieties De árbol and Jalapeño decreased. However, the pungency values found in this study were higher for all varieties analyzed than in other studies.

  15. The Effect of High Temperature Annealing on the Grain Characteristics of a Thin Chemical Vapor Deposition Silicon Carbide Layer.

    Energy Technology Data Exchange (ETDEWEB)

    Isabella J van Rooyen; Philippus M van Rooyen; Mary Lou Dunzik-Gougar

    2013-08-01

    The unique combination of thermo-mechanical and physiochemical properties of silicon carbide (SiC) provides interest and opportunity for its use in nuclear applications. One of the applications of SiC is as a very thin layer in the TRi-ISOtropic (TRISO) coated fuel particles for high temperature gas reactors (HTGRs). This SiC layer, produced by chemical vapor deposition (CVD), is designed to withstand the pressures of fission and transmutation product gases in a high temperature, radiation environment. Various researchers have demonstrated that macroscopic properties can be affected by changes in the distribution of grain boundary plane orientations and misorientations [1 - 3]. Additionally, various researchers have attributed the release behavior of Ag through the SiC layer as a grain boundary diffusion phenomenon [4 - 6]; further highlighting the importance of understanding the actual grain characteristics of the SiC layer. Both historic HTGR fission product release studies and recent experiments at Idaho National Laboratory (INL) [7] have shown that the release of Ag-110m is strongly temperature dependent. Although the maximum normal operating fuel temperature of a HTGR design is in the range of 1000-1250°C, the temperature may reach 1600°C under postulated accident conditions. The aim of this specific study is therefore to determine the magnitude of temperature dependence on SiC grain characteristics, expanding upon initial studies by Van Rooyen et al, [8; 9].

  16. High Temperature Effects on Yeast-like Endosymbiotes and Pesticide Resistance of the Small Brown Planthopper, Laodelphax striatellus

    Directory of Open Access Journals (Sweden)

    Xiao-jie ZHANG

    2008-12-01

    Full Text Available The newly-hatched nymphs of the small brown planthopper (SBPH, Laodelphax striatellus, including field and sensitive populations, were subjected to the high-temperature (35°C treatment. The number of yeast-like endosymbiotes in SBPH reduced by 23.47%–34.23%, 57.86%–61.51% and 88.96%–90.71% after the high-temperature treatment for 1 d, 2 d, and 3 d, respectively. However, the size of yeast-like endosymbiotes was not obviously affected. Resistance of SBPH to three insecticides (imidacloprid, chlorpyrifos and fipronil decreased with the increase of treatment time.

  17. [Changes of heavy metals form during aerobic high temperature composting of pig manure and the effects of passivators].

    Science.gov (United States)

    He, Zeng-ming; Liu, Qiang; Xie, Gui-xian; Rong, Xiang-min; Peng, Jian-wei; Song, Hai-xing; Li, Lian-fang; Su, Shi-ming

    2010-10-01

    Sequential extraction method was employed to study the heavy metals concentration and form change during aerobic high temperature compositing of pig manure, and the effects of amendment with different proportion of passivators on the concentration and form change. During the composting process, the concentrations of total As, Cu, and Zn in the manure all increased to some extent. As for the form change of the heavy metals, the exchangeable As and Zn decreased while the residual As and Zn increased, indicating that the availability of As and Zn declined through the composting process. On the other hand, the exchangeable and residual Cu decreased while the carbonate-, Fe/Mn-, and organic bound Cu increased, suggesting the potential environmental risk of the future application of the compost. Among the passivators amended, 5.0% of sepiolite and 2.5% of bentonite had the best effect in reducing the availability of As and Zn, with the residual form of As and Zn after composting increased by 79.8% and 158.6%, respectively, and 7.5% of sepiolite induced the least decrement (39.3%) of residual Cu, compared with the control. Therefore, amendment with appropriate proportion of passivator during pig manure composting could decrease the availability of heavy metals in the manure, and reduce the environmental risk of applying the compost to farmland.

  18. Effect of High Temperature Hot Corrosion on the Compression Creep Behavior of 12Cr1MoV Alloys

    Science.gov (United States)

    He, Jianjun; Xiong, Weizhou

    2017-10-01

    This paper highlights the effect of 70 %NaCl-30 %KCl salt mixture on compression creep properties of 12Cr1MoV alloys at 100 MPa (948.15 K, 973.15 K and 998.15 K) in air using bare specimens and specimens in corrosive environment. The corrosive specimens were also tested at 923.15 K (150 MPa, 175 MPa and 200 MPa). Experimental results showed that the specimen in chloride mixture showed relatively high compression creep strain and steady-state creep rates compared with the bare specimen, and this effect accelerated with the increased temperature, especially when it was above 973.15 K. The creep mechanisms of the specimen in chloride mixture were inferred from gliding and climbing of dislocations of the stress exponent. Damage of hot corrosion in creep deformation was found to be associated with the layer fracture attributing to the initiation and propagation from the intergranular cracks and reduction of the bare area caused by the internal transgranular attack of chloride mixture.

  19. High Summer Temperatures and Mortality in Estonia.

    Directory of Open Access Journals (Sweden)

    Daniel Oudin Åström

    Full Text Available On-going climate change is predicted to result in a growing number of extreme weather events-such as heat waves-throughout Europe. The effect of high temperatures and heat waves are already having an important impact on public health in terms of increased mortality, but studies from an Estonian setting are almost entirely missing. We investigated mortality in relation to high summer temperatures and the time course of mortality in a coastal and inland region of Estonia.We collected daily mortality data and daily maximum temperature for a coastal and an inland region of Estonia. We applied a distributed lag non-linear model to investigate heat related mortality and the time course of mortality in Estonia.We found an immediate increase in mortality associated with temperatures exceeding the 75th percentile of summer maximum temperatures, corresponding to approximately 23°C. This increase lasted for a couple of days in both regions. The total effect of elevated temperatures was not lessened by significant mortality displacement.We observed significantly increased mortality in Estonia, both on a country level as well as for a coastal region and an inland region with a more continental climate. Heat related mortality was higher in the inland region as compared to the coastal region, however, no statistically significant differences were observed. The lower risks in coastal areas could be due to lower maximum temperatures and cooling effects of the sea, but also better socioeconomic condition. Our results suggest that region specific estimates of the impacts of temperature extremes on mortality are needed.

  20. High Summer Temperatures and Mortality in Estonia.

    Science.gov (United States)

    Oudin Åström, Daniel; Åström, Christofer; Rekker, Kaidi; Indermitte, Ene; Orru, Hans

    2016-01-01

    On-going climate change is predicted to result in a growing number of extreme weather events-such as heat waves-throughout Europe. The effect of high temperatures and heat waves are already having an important impact on public health in terms of increased mortality, but studies from an Estonian setting are almost entirely missing. We investigated mortality in relation to high summer temperatures and the time course of mortality in a coastal and inland region of Estonia. We collected daily mortality data and daily maximum temperature for a coastal and an inland region of Estonia. We applied a distributed lag non-linear model to investigate heat related mortality and the time course of mortality in Estonia. We found an immediate increase in mortality associated with temperatures exceeding the 75th percentile of summer maximum temperatures, corresponding to approximately 23°C. This increase lasted for a couple of days in both regions. The total effect of elevated temperatures was not lessened by significant mortality displacement. We observed significantly increased mortality in Estonia, both on a country level as well as for a coastal region and an inland region with a more continental climate. Heat related mortality was higher in the inland region as compared to the coastal region, however, no statistically significant differences were observed. The lower risks in coastal areas could be due to lower maximum temperatures and cooling effects of the sea, but also better socioeconomic condition. Our results suggest that region specific estimates of the impacts of temperature extremes on mortality are needed.

  1. High Temperature Superconductor Accelerator Magnets

    CERN Document Server

    AUTHOR|(CDS)2079328; de Rijk, Gijs; Dhalle, Marc

    2016-11-10

    For future particle accelerators bending dipoles are considered with magnetic fields exceeding $20T$. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and development before they can be applied in a practical accelerator magnet. In order to study HTS in detail, a five tesla demonstrator magnet named Feather-M2 is designed and constructed. The magnet is based on ReBCO coated conductor, which is assembled into a $10kA$ class Roebel cable. A new and optimized Aligned Block layout is used, which takes advantage of the anisotropy of the conductor. This is achieved by providing local alignment of the Roebel cable in the coil windings with the magnetic field lines. A new Network Model capable of analyzing transient electro-magnetic and thermal phenomena in coated conductor cables and coils is developed. This model is necessary to solve critical issues in coated conductor ac...

  2. [Effect of seasonal high temperature and drought on carbon flux of bamboo forest ecosystem in subtropical region].

    Science.gov (United States)

    Chen, Xiao-feng; Jiang, Hong; Niu, Xiao-dong; Zhang, Jin-meng; Liu, Yu-li; Fang, Cheng-yuan

    2016-02-01

    The carbon flux of subtropical bamboo forest ecosystem was continuously measured using eddy covariance technique in Anji County of Zhejiang Province, China. The monthly net ecosystem productivity (NEP), ecosystem respiration (Re) and gross ecosystem productivity (GEP) data from 2011 to 2013 were selected to analyze the impacts of seasonal high temperature and drought on the carbon flux of bamboo forest ecosystem. The results showed that there were big differences among annual NEP of bamboo forest from 2011 to 2013. Because of the asynchronization of precipitation and heat, the seasonal high temperature and drought in July and August of 2013 caused significant decline in NEP by 59.9% and 80.0% when compared with the same months in 2011. Correlation analysis of the NEP, Re, GEP and environmental factors suggested that the atmosphere temperatures were significantly correlated with Re and GEP in 2011 and 2013 (Pecosystem in Anji, from July to August in 2013.

  3. Faraday imaging at high temperatures

    Science.gov (United States)

    Hackel, Lloyd A.; Reichert, Patrick

    1997-01-01

    A Faraday filter rejects background light from self-luminous thermal objects, but transmits laser light at the passband wavelength, thus providing an ultra-narrow optical bandpass filter. The filter preserves images so a camera looking through a Faraday filter at a hot target illuminated by a laser will not see the thermal radiation but will see the laser radiation. Faraday filters are useful for monitoring or inspecting the uranium separator chamber in an atomic vapor laser isotope separation process. Other uses include viewing welds, furnaces, plasma jets, combustion chambers, and other high temperature objects. These filters are can be produced at many discrete wavelengths. A Faraday filter consists of a pair of crossed polarizers on either side of a heated vapor cell mounted inside a solenoid.

  4. Study Progress of Physiological Responses in High Temperature Environment

    Science.gov (United States)

    Li, K.; Zheng, G. Z.; Bu, W. T.; Wang, Y. J.; Lu, Y. Z.

    2017-10-01

    Certain workers are exposed to high temperatures for a long time. Heat stress will result in a series of physiological responses, and cause adverse effects on the health and safety of workers. This paper summarizes the physiological changes of cardiovascular system, core temperature, skin temperature, water-electrolyte metabolism, alimentary system, neuroendocrine system, reaction time and thermal fatigue in high temperature environments. It can provide a theoretical guidance for labor safety in high temperature environment.

  5. High temperature operation of n-AlGaN channel metal semiconductor field effect transistors on low-defect AlN templates

    Science.gov (United States)

    Muhtadi, S.; Hwang, S.; Coleman, A.; Asif, F.; Lunev, A.; Chandrashekhar, M. V. S.; Khan, A.

    2017-05-01

    We report room-temperature to 200 °C operation of n-Al0.65Ga0.35N channel metal semiconductor field effect transistors (MESFET) grown over high-quality AlN/sapphire templates. For this temperature range, the source-drain currents, threshold voltages, and dc-transconductance values remain nearly unchanged with an estimated field-effect mobility of ˜90 cm2/V-s at 200 °C and currents of >100 mA/mm. The analysis of the temperature dependent current-voltage characteristics of the gate-source Schottky barrier diode reveals that the leakage currents arise from Frenkel-Poole emission. The capacitance-voltage data show no hysteresis, indicating a high quality Schottky barrier interface. These MESFET's have excellent potential for use as a high temperature power electronic or a solar-blind ultraviolet sensing device.

  6. Surface Effects and Challenges for Application of Piezoelectric Langasite Substrates in Surface Acoustic Wave Devices Caused by High Temperature Annealing under High Vacuum

    Directory of Open Access Journals (Sweden)

    Marietta Seifert

    2015-12-01

    Full Text Available Substrate materials that are high-temperature stable are essential for sensor devices which are applied at high temperatures. Although langasite is suggested as such a material, severe O and Ga diffusion into an O-affine deposited film was observed during annealing at high temperatures under vacuum conditions, leading to a damage of the metallization as well as a change of the properties of the substrate and finally to a failure of the device. Therefore, annealing of bare LGS (La 3 Ga 5 SiO 14 substrates at 800 ∘ C under high vacuum conditions is performed to analyze whether this pretreatment improves the suitability and stability of this material for high temperature applications in vacuum. To reveal the influence of the pretreatment on the subsequently deposited metallization, RuAl thin films are used as they are known to oxidize on LGS at high temperatures. A local study of the pretreated and metallized substrates using transmission electron microscopy reveals strong modification of the substrate surface. Micro cracks are visible. The composition of the substrate is strongly altered at those regions. Severe challenges for the application of LGS substrates under high-temperature vacuum conditions arise from these substrate damages, revealing that the pretreatment does not improve the applicability.

  7. Measuring nanowire thermal conductivity at high temperatures

    Science.gov (United States)

    Wang, Xiaomeng; Yang, Juekuan; Xiong, Yucheng; Huang, Baoling; Xu, Terry T.; Li, Deyu; Xu, Dongyan

    2018-02-01

    This work extends the micro-thermal-bridge method for thermal conductivity measurements of nanowires to high temperatures. The thermal-bridge method, based on a microfabricated device with two side-by-side suspended membranes with integrated platinum resistance heaters/thermometers, has been used to determine thermal conductivity of various nanowires/nanotubes/nanoribbons at relatively low temperatures. However, to date, thermal conductivity characterization of nanowires at temperatures above 600 K has seldom been reported presumably due to several technical difficulties including the instability of the microfabricated thermometers, radiation heat loss, and the effect of the background conductance on the measurement. Here we report on our attempt to address the aforementioned challenges and demonstrate thermal conductivity measurement of boron nanoribbons up to 740 K. To eliminate high temperature resistance instability, the device is first annealed at 1023 K for 5 min in an argon atmosphere. Two radiation shields are installed in the measurement chamber to minimize radiation heat loss from the measurement device to the surroundings; and the temperature of the device at each set point is calibrated by an additional thermocouple directly mounted on the chip carrier. The effect of the background conductance is eliminated by adopting a differential measurement scheme. With all these modifications, we successfully measured the thermal conductivity of boron nanoribbons over a wide temperature range from 27 K to 740 K. The measured thermal conductivity increases monotonically with temperature and reaches a plateau of ~2.5 W m‑1 K‑1 at approximately 400 K, with no clear signature of Umklapp scattering observed in the whole measurement temperature range.

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

    Science.gov (United States)

    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.

  9. Hysteresis in Lanthanide Zirconium Oxides Observed Using a Pulse CV Technique and including the Effect of High Temperature Annealing

    Directory of Open Access Journals (Sweden)

    Qifeng Lu

    2015-07-01

    Full Text Available A powerful characterization technique, pulse capacitance-voltage (CV technique, was used to investigate oxide traps before and after annealing for lanthanide zirconium oxide thin films deposited on n-type Si (111 substrates at 300 °C by liquid injection Atomic Layer Deposition (ALD. The results indicated that: (1 more traps were observed compared to the conventional capacitance-voltage characterization method in LaZrOx; (2 the time-dependent trapping/de-trapping was influenced by the edge time, width and peak-to-peak voltage of a gate voltage pulse. Post deposition annealing was performed at 700 °C, 800 °C and 900 °C in N2 ambient for 15 s to the samples with 200 ALD cycles. The effect of the high temperature annealing on oxide traps and leakage current were subsequently explored. It showed that more traps were generated after annealing with the trap density increasing from 1.41 × 1012 cm−2 for as-deposited sample to 4.55 × 1012 cm−2 for the 800 °C annealed one. In addition, the leakage current density increase from about 10−6 A/cm2 at Vg = +0.5 V for the as-deposited sample to 10−3 A/cm2 at Vg = +0.5 V for the 900 °C annealed one.

  10. Effects of Fe3+ and Antioxidants on Glycidyl Ester Formation in Plant Oil at High Temperature and Their Influencing Mechanisms.

    Science.gov (United States)

    Cheng, Weiwei; Liu, Guoqin; Liu, Xinqi

    2017-05-24

    This research investigated the effects of Fe3+ and antioxidants on the formation of glycidyl esters (GEs) and the free radical mediated mechanisms involving the recognition of cyclic acyloxonium free radical intermediate (CAFRI) for GE formation in both the plant oil model (palm oil, camellia oil, soybean oil, and linseed oil) system and the chemical model (dipalmitin and methyl linoleate) system heated at 200 °C. Results show that Fe3+ can promote the formation of GEs, which can be inhibited by antioxidants in plant oil during high-temperature exposure. Based on the monitoring of cyclic acyloxonium and ester carbonyl group by Fourier transform infrared spectroscopy, the promotion of Fe3+ and the inhibition of antioxidants (tert-butylhydroquinone and α-tocopherol) for GE formation occurred not only through lipid oxidation but also through directly affecting the formation of cyclic acyloxonium intermediate. Additionally, a quadrupole time-of-flight tandem mass spectrometry measurement was conducted to identify the presence of radical adduct captured by 5,5-dimethylpyrroline N-oxide, which provided strong evidence for the formation of CAFRI. Thus, one possible influencing mechanism can be that free radical generated in lipid oxidation may be transferred to dipalmitin and promote CAFRI formation. Fe3+ can catalyze free radical generation while antioxidants can scavenge free radical, and therefore they also can directly affect CAFRI formation.

  11. Effect of pre-oxidation on high temperature sulfidation behavior of FeCr and FeCrAl alloys

    Directory of Open Access Journals (Sweden)

    Pillis Marina Fuser

    2004-01-01

    Full Text Available High temperature corrosion of structural alloys in sulfur bearing environments is many orders of magnitude higher than in oxidizing environments. Efforts to increase sulfidation resistance of these alloys include addition of alloying elements. Aluminum additions to iron-chromium alloys bring about increase in sulfidation resistance. This paper reports the effect of pre-oxidation on the sulfidation behavior of Fe-20Cr and Fe-20Cr-5Al alloys in H2-2% H2S environment at 800 °C. The surfaces of sulfidized specimens were also examined. Pre-oxidation of the two alloys results in an incubation period during subsequent sulfidation. After this incubation period, the Fe-20Cr alloy showed sulfidation behavior similar to that when the alloy was not pre-oxidized. The incubation period during sulfidation of the Fe-20Cr-5Al alloy was significantly longer, over 45 h, compared to 2 h for the Al free alloy. Based on the microscopic and gravimetric data a mechanism for sulfidation of these alloys with pre-oxidation has been proposed.

  12. Gasification of high ash, high ash fusion temperature bituminous coals

    Science.gov (United States)

    Liu, Guohai; Vimalchand, Pannalal; Peng, WanWang

    2015-11-13

    This invention relates to gasification of high ash bituminous coals that have high ash fusion temperatures. The ash content can be in 15 to 45 weight percent range and ash fusion temperatures can be in 1150.degree. C. to 1500.degree. C. range as well as in excess of 1500.degree. C. In a preferred embodiment, such coals are dealt with a two stage gasification process--a relatively low temperature primary gasification step in a circulating fluidized bed transport gasifier followed by a high temperature partial oxidation step of residual char carbon and small quantities of tar. The system to process such coals further includes an internally circulating fluidized bed to effectively cool the high temperature syngas with the aid of an inert media and without the syngas contacting the heat transfer surfaces. A cyclone downstream of the syngas cooler, operating at relatively low temperatures, effectively reduces loading to a dust filtration unit. Nearly dust- and tar-free syngas for chemicals production or power generation and with over 90%, and preferably over about 98%, overall carbon conversion can be achieved with the preferred process, apparatus and methods outlined in this invention.

  13. High temperature and risk of hospitalizations, and effect modifying potential of socio-economic conditions: A multi-province study in the tropical Mekong Delta Region.

    Science.gov (United States)

    Phung, Dung; Guo, Yuming; Nguyen, Huong T L; Rutherford, Shannon; Baum, Scott; Chu, Cordia

    2016-01-01

    The Mekong Delta Region (MDR) in Vietnam is highly vulnerable to extreme weather related to climate change. However there have been hardly any studies on temperature-hospitalization relationships. The objectives of this study were to examine temperature-hospitalization relationship and to evaluate the effects of socio-economic factors on the risk of hospitalizations due to high temperature in the MDR. The Generalized Linear and Distributed Lag Models were used to examine hospitalizations for extreme temperature for each of the 13 provinces in the MDR. A random-effects meta-analysis was used to estimate the pooled risk for all causes, and for infectious, cardiovascular, and respiratory diseases sorted by sex and age groups. Random-effects meta-regression was used to evaluate the effect of socio-economic factors on the temperature-hospitalization association. For 1°C increase in average temperature, the risk of hospital admissions increased by 1.3% (95% CI, 0.9-1.8) for all causes, 2.2% (95% CI, 1.4-3.1) for infectious diseases, and 1.1% (95% CI, 0.5-1.7) for respiratory diseases. However the result was inconsistent for cardiovascular diseases. Meta-regression showed population density, poverty rate, and illiteracy rate increased the risk of hospitalization due to high temperature, while higher household income, houses using safe water, and houses using hygienic toilets reduced this risk. In the MDR, high temperatures have a significant impact on hospitalizations for infectious and respiratory diseases. Our findings have important implications for better understanding the future impacts of climate change on residents of the MDR. Adaptation programs that consider the risk and protective factors should be developed to protect residents from extreme temperature conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Effects of oxygen nonstoichiometry on the high-temperature performance of an yttria-tetragonal zirconia polycrystal material

    Energy Technology Data Exchange (ETDEWEB)

    Swab, J.J.; Katz, R.N.; Starita, C.J. (Army Materials Technology Lab., Watertown, MA (USA))

    1988-05-01

    The hot isostatic pressing of an yttria-tetragonal zirconia polycrystal (Y-TZP) powder yields a body that is slightly reduced. Stepped-temperature stress-rupture tests revealed that a hot isostatically pressed Y-TZP has anomalous time-dependent failure behavior through the temperature range 800{degree} to 1,200{degree}C. However, this anomaly can effectively be eliminated, and the stress-rupture performance significantly improved, by oxidizing the pressed body at 1,000{degree}C before use.

  15. Study on the Effects of Liquid Thermal Media on the Irradiation Capsule of High-Temperature Materials

    Directory of Open Access Journals (Sweden)

    Man Soon Cho

    2015-01-01

    Full Text Available Irradiation tests of materials at HANARO have usually been conducted using a standard capsule at temperatures of about 300°C for irradiation of materials used at PWR. Thus, the standard capsule uses aluminum as the specimen holder, which acts to dissipate the thermal energy. Future nuclear systems such as a VHTR and SFR require the irradiation tests at a relatively high temperature. As an alternative to aluminum which has been used as the thermal media in a standard material capsule, the characteristics of liquid metals such as NaK and LBE are reviewed. The temperatures of the capsule are affected by the variation of parameters such as the gap and wall thickness of the container. In particular, the external gap is most important in determining the temperature of the specimen. LBE raises the temperature of the specimen higher than NaK at the same configuration of the capsule. Thus, LBE can lessen the gap of the parts and reduce the vibration for a stable long-term test in reactor.

  16. Effects of temperature and light on the formation of chloroplast protrusions in leaf mesophyll cells of high alpine plants.

    Science.gov (United States)

    Buchner, Othmar; Holzinger, Andreas; Lütz, Cornelius

    2007-11-01

    Chloroplasts of many alpine plants have the ability to form marked, stroma-filled protrusions that do not contain thylakoids. Effects of temperature and light intensity on the frequency of chloroplasts with such protrusions in leaf mesophyll cells of nine different alpine plant species (Carex curvula All., Leontodon helveticus Merat., Oxyria digyna (L.) Hill., Poa alpina L. ssp. vivipara, Polygonum viviparum L., Ranunculus glacialis L., Ranunculus alpestris L., Silene acaulis L. and Soldanella pusilla Baumg.) covering seven different families were studied. Leaves were exposed to either darkness and a stepwise increase in temperature (10-38 degrees C) or to different light intensities (500 and 2000 micromol photons m(-2) s(-1)) and a constant temperature of 10 or 30 degrees C in a special temperature-regulated chamber. A chloroplast protrusions index characterising the relative proportion of chloroplasts with protrusions was defined. Seven of the nine species showed a significant increase in chloroplast protrusions when temperature was elevated to over 20 degrees C. In contrast, the light level did not generally affect the abundance of chloroplasts with protrusions. Chloroplast protrusions lead to a dynamic enlargement of the chloroplast surface area. They do not appear to be directly connected to a distinct photosystem II (PSII) (F(v)/F(m)) status and thus seem to be involved in secondary, not primary, photosynthetic processes.

  17. High-temperature borehole instrumentation

    Science.gov (United States)

    Dennis, B. R.; Koczan, S. P.; Stephani, E. L.

    1985-10-01

    A new method of extracting natural heat from the Earth's crust was invented at the Los Alamos National Laboratory in 1970. It uses fluid pressures (hydraulic fracturing) to produce cracks that connect two boreholes drilled into hot rock formations of low initial permeability. Pressurized water is then circulated through this connected underground loop to extract heat from the rock and bring it to the surface. The creation of the fracture reservior began with drilling boreholes deep within the Precambrian basement rock at the Fenton Hill Test Site. Hydraulic fracturing, flow testing, and well-completion operations required unique wellbore measurements using downhole instrumentation systems that would survive the very high borehole temperatures, 320(0)C (610(0)F). These instruments were not available in the oil and gas industrial complex, so the Los Alamos National Laboratory initiated an intense program upgrading existing technology where applicable, subcontracting materials and equipment development to industrial manufactures, and using the Laboratory resources to develop the necessary downhole instruments to meet programmatic schedules.

  18. No copper supplementation in a corn-soybean basal diet has no adverse effects on late-phase laying hens under normal and cyclic high temperatures.

    Science.gov (United States)

    Li, W X; Chen, Y Q; Zhao, L H; Ma, Q G; Zhang, J Y; Ji, C

    2018-02-14

    Over supplementation of copper (Cu) in animal diets may cause serious pollution in soil, water and harvested crops. To minimize the potential pollution, the effects of corn-soybean basal diet with or without supplementation of 8 mg Cu/kg on laying performance, plasma biochemical metabolic indices, and antioxidant status in laying hens were evaluated under normal and cyclic high temperatures. A total of 240 Hy-Line Brown laying hens were randomly allotted to 4 treatments with 6 replicates of 10 hens per replicate according to factorial design involved in 2 temperatures [normal temperature (NT) vs. cyclic high temperature (CHT)] and 2 dietary Cu addition amount [Cu0 (0 mg/kg) vs. Cu8 (8 mg/kg in the form of CuSO4·5H2O)]. The experimental period included 1-week adaptation, 2-week heat stress and 2-week convalescence. The temperatures of NT groups in the same period or any groups during other periods were kept at 26 ± 2°C except that of CHT groups were 26 ± 2°C∼33 ± 2°C cyclically during heat stress period. CHT groups increased (P temperature and plasma glucose content under heat stress, but decreased (P temperature and Cu content existed (P high (26 ± 2°C∼33 ± 2°C) or normal (26 ± 2°C) temperatures. © 2018 Poultry Science Association Inc.

  19. The Combined Effect of High Ambient Temperature and Antihypertensive Treatment on Renal Function in Hospitalized Elderly Patients.

    Directory of Open Access Journals (Sweden)

    Iftach Sagy

    Full Text Available The aging kidney manifests structural, functional as well as pharmacological changes, rendering elderly patients more susceptible to adverse environmental influences on their health, dehydration in particular.Higher temperature is associated with renal function impairment in patients 65 years and older who routinely take thiazide and/or ACE-inhibitors/ARBs.We obtained health data of patients older than 65 who were admitted to a large tertiary center during the years 2006-2011, with a previous diagnosis of hypertension, and treated with thiazide, ACE-inhibitors/ARBs or both. We collected environmental data of daily temperature, available from collaborative public and governmental institutions. In order to estimate the effect of daily temperature on renal function we performed linear mixed models, separately for each treatment group and creatinine change during hospital admission.We identified 26,286 admissions for 14, 268 patients with a mean age of 75.6 (±6.9 years, of whom 53.6% were men. Increment in daily temperature on admission of 5°C had significant effect on creatinine increase in the no treatment (baseline creatinine adjusted 0.824 mg/dL, % change 1.212, % change 95% C.I 0.082-2.354 and dual treatment groups (baseline creatinine adjusted 1.032mg/dL, % change 3.440, % change 95% C.I 1.227-5.700. Sub-analysis stratified by advanced age, chronic kidney disease and primary diagnosis on hospital admission, revealed a significant association within patients admitted due to acute infection and treated with dual therapy.Whereas previous studies analyzed sporadic climate effects during heat waves and/or excluded older population taking anti-hypertensive medications, the present study is novel by showing a durable association of temperature and decreased renal function specifically in elderly patients taking anti-hypertensive medications.

  20. Effect of tungsten addition on high-temperature properties and microstructure of alumina-forming austenitic heat-resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Min-Ho [Division of Materials Science and Engineering, Hanyang University, Seongdong-ku, Seoul 133-791 (Korea, Republic of); Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Moon, Joonoh; Kang, Jun-Yun; Ha, Heon-Young [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Choi, Baig Gyu [High Temperature Materials Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Lee, Tae-Ho [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Lee, Changhee, E-mail: chlee@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, Seongdong-ku, Seoul 133-791 (Korea, Republic of)

    2015-10-28

    High-temperature tensile and creep properties of W-added Alumina-Forming austenitic (AFA{sub W}) heat-resistant steel were investigated as compared with AFA steel without W. High-temperature tensile properties of two steels were similar to each other, but creep lifetime of AFA{sub W} steel was increased. Microstructural examination using SEM and TEM revealed that creep rate rapidly decreased when Laves phase initially precipitated. This indicated that the precipitation of Laves phase played an important role in hardening of AFA steel. It is also found that AFA{sub W} steel exhibited finer and denser Laves phase compared with AFA steel, which is due to partial substitution of W for Mo. The finer and denser distribution of Laves phase contributed to improved creep properties of AFA{sub W} steel by enhancement in precipitation hardening.

  1. High Temperature Chemistry at NASA: Hot Topics

    Science.gov (United States)

    Jacobson, Nathan S.

    2014-01-01

    High Temperature issues in aircraft engines Hot section: Ni and Co based Superalloys Oxidation and Corrosion (Durability) at high temperatures. Thermal protection system (TPS) and RCC (Reinforced Carbon-Carbon) on the Space Shuttle Orbiter. High temperatures in other worlds: Planets close to their stars.

  2. High temperature vapors science and technology

    CERN Document Server

    Hastie, John

    2012-01-01

    High Temperature Vapors: Science and Technology focuses on the relationship of the basic science of high-temperature vapors to some areas of discernible practical importance in modern science and technology. The major high-temperature problem areas selected for discussion include chemical vapor transport and deposition; the vapor phase aspects of corrosion, combustion, and energy systems; and extraterrestrial high-temperature species. This book is comprised of seven chapters and begins with an introduction to the nature of the high-temperature vapor state, the scope and literature of high-temp

  3. Effects of High Temperature and Thermal Cycling on the Performance of Perovskite Solar Cells: Acceleration of Charge Recombination and Deterioration of Charge Extraction.

    Science.gov (United States)

    Sheikh, Arif D; Munir, Rahim; Haque, Md Azimul; Bera, Ashok; Hu, Weijin; Shaikh, Parvez; Amassian, Aram; Wu, Tom

    2017-10-11

    In this work, we investigated the effects of high operating temperature and thermal cycling on the photovoltaic (PV) performance of perovskite solar cells (PSCs) with a typical mesostructured (m)-TiO2-CH3NH3PbI3-xClx-spiro-OMeTAD architecture. After temperature-dependent grazing-incidence wide-angle X-ray scattering, in situ X-ray diffraction, and optical absorption experiments were carried out, the thermal durability of PSCs was tested by subjecting the devices to repetitive heating to 70 °C and cooling to room temperature (20 °C). An unexpected regenerative effect was observed after the first thermal cycle; the average power conversion efficiency (PCE) increased by approximately 10% in reference to the as-prepared device. This increase of PCE was attributed to the heating-induced improvement of the crystallinity and p doping in the hole transporter, spiro-OMeTAD, which promotes the efficient extraction of photogenerated carriers. However, further thermal cycles produced a detrimental effect on the PV performance of PSCs, with the short-circuit current and fill factor degrading faster than the open-circuit voltage. Similarly, the PV performance of PSCs degraded at high operation temperatures; both the short-circuit current and open-circuit voltage decreased with increasing temperature, but the temperature-dependent trend of the fill factor was the opposite. Our impedance spectroscopy analysis revealed a monotonous increase of the charge-transfer resistance and a concurrent decrease of the charge-recombination resistance with increasing temperature, indicating a high recombination of charge carriers. Our results revealed that both thermal cycling and high temperatures produce irreversible detrimental effects on the PSC performance because of the deteriorated interfacial photocarrier extraction. The present findings suggest that the development of robust charge transporters and proper interface engineering are critical for the deployment of perovskite PVs in harsh

  4. Effects of High Temperature and Thermal Cycling on the Performance of Perovskite Solar Cells: Acceleration of Charge Recombination and Deterioration of Charge Extraction

    KAUST Repository

    Sheikh, Arif D.

    2017-09-18

    In this work, we investigated the effects of high operating temperature and thermal cycling on the photovoltaic performance of perovskite solar cells (PSCs) with a typical mesostructured (m)-TiO2-CH3NH3PbI3-xClx-spiro-OMeTAD architecture. After carrying out temperature-dependent grazing incidence wide-angle X-ray scattering (GIWAXS), in-situ X-ray diffraction (XRD) and optical absorption experiments, thermal durability of PSCs was tested by subjecting the devices to repetitive heating to 70 °C and cooling to room temperature (20 °C). An unexpected regenerative effect was observed after the first thermal cycle; the average power conversion efficiency (PCE) increased by approximately 10 % in reference to the as-prepared device. This increase of PCE was attributed to the heating-induced improvement of crystallinity and p-doping in the hole-transporter, Spiro-OMeTAD, which promotes the efficient extraction of photo-generated carriers. However, further thermal cycles produced a detrimental effect on the photovoltaic performance of PSCs with short-circuit current and fill factor degrading faster than the open-circuit voltage. Similarly, the photovoltaic performance of PSCs degraded at high operation temperatures; both short-circuit current and open-circuit voltage decreased with increasing temperature, but the temperature-dependent trend of fill factor was opposite. Our impedance spectroscopy analysis revealed a monotonous increase of charge transfer resistance and a concurrent decrease of charge recombination resistance with increasing temperature, indicating high recombination of charge carriers. Our results revealed that both thermal cycling and high temperatures produce irreversible detrimental effects on the PSC performance due to the deteriorated interfacial photo-carrier extraction. The present findings suggest that development of robust charge transporters and proper interface engineering are critical for the deployment of perovskite photovoltaics in harsh

  5. High temperature and vapor pressure deficit aggravate architectural effects but ameliorate non-architectural effects of salinity on dry mass production of tomato

    Directory of Open Access Journals (Sweden)

    Tsu-Wei eChen

    2015-10-01

    Full Text Available Tomato (Solanum lycopersicum L. is an important vegetable crop and often cultivated in regions exposed to salinity and high temperatures (HT which change plant architecture, decrease canopy light interception and disturb physiological functions. However, the long-term effects of salinity and HT combination (S+HT on plant growth are still unclear. A dynamic functional-structural plant model (FSPM of tomato was parameterized and evaluated for different levels of S+HT combinations. The evaluated model was used to quantify the contributions of morphological changes (architectural effects and physiological disturbances (non-architectural effects on the reduction of shoot dry mass under S+HT. The model predicted dynamic plant architecturale variables with high accuracy (> 85%, which ensured the reliability of the model analyses. HT enhanced architectural effects but reduced non-architectural effects of salinity on dry mass production. The stronger architectural effects of salinity under HT could not be counterbalanced by the smaller non-architectural effects. Therefore, long-term influences of HT on shoot dry mass under salinity were negative at the whole plant level. Our model analysis highlights the importance of plant architecture at canopy level in studying the plant responses to the environments and shows the merits of dynamic FSPMs as heuristic tools.

  6. Pre-anthesis high temperature acclimation alleviates the negative effects of post-anthesis heat stress on stem stored carbohydrates remobilization and grain starch accumulation in wheat

    DEFF Research Database (Denmark)

    Wang, Xiao; Cai, Jian; Liu, Fulai

    2012-01-01

    The potential role of pre-anthesis high temperature acclimation in alleviating the negative effects of post-anthesis heat stress on stem stored carbohydrate remobilization and grain starch accumulation in wheat was investigated. The treatments included no heat-stress (CC), heat stress at pre...... had much higher starch content, and caused less modified B-type starch granule size indicators than the CH plants. Our results indicated that, compared with the non-acclimated plants, the pre-anthesis high temperature acclimation effectively enhanced carbohydrate remobilization from stems to grains...

  7. Effect of ultra high temperature ceramics as fuel cladding materials on the nuclear reactor performance by SERPENT Monte Carlo code

    Energy Technology Data Exchange (ETDEWEB)

    Korkut, Turgay; Kara, Ayhan; Korkut, Hatun [Sinop Univ. (Turkey). Dept. of Nuclear Energy Engineering

    2016-12-15

    Ultra High Temperature Ceramics (UHTCs) have low density and high melting point. So they are useful materials in the nuclear industry especially reactor core design. Three UHTCs (silicon carbide, vanadium carbide, and zirconium carbide) were evaluated as the nuclear fuel cladding materials. The SERPENT Monte Carlo code was used to model CANDU, PWR, and VVER type reactor core and to calculate burnup parameters. Some changes were observed at the same burnup and neutronic parameters (keff, neutron flux, absorption rate, and fission rate, depletion of U-238, U-238, Xe-135, Sm-149) with the use of these UHTCs. Results were compared to conventional cladding material zircalloy.

  8. The effects of composition, temperature and sample size on the sintering of chem-prep high field varistors.

    Energy Technology Data Exchange (ETDEWEB)

    Garino, Terry J.

    2007-09-01

    The sintering behavior of Sandia chem-prep high field varistor materials was studied using techniques including in situ shrinkage measurements, optical and scanning electron microscopy and x-ray diffraction. A thorough literature review of phase behavior, sintering and microstructure in Bi{sub 2}O{sub 3}-ZnO varistor systems is included. The effects of Bi{sub 2}O{sub 3} content (from 0.25 to 0.56 mol%) and of sodium doping level (0 to 600 ppm) on the isothermal densification kinetics was determined between 650 and 825 C. At {ge} 750 C samples with {ge}0.41 mol% Bi{sub 2}O{sub 3} have very similar densification kinetics, whereas samples with {le}0.33 mol% begin to densify only after a period of hours at low temperatures. The effect of the sodium content was greatest at {approx}700 C for standard 0.56 mol% Bi{sub 2}O{sub 3} and was greater in samples with 0.30 mol% Bi{sub 2}O{sub 3} than for those with 0.56 mol%. Sintering experiments on samples of differing size and shape found that densification decreases and mass loss increases with increasing surface area to volume ratio. However, these two effects have different causes: the enhancement in densification as samples increase in size appears to be caused by a low oxygen internal atmosphere that develops whereas the mass loss is due to the evaporation of bismuth oxide. In situ XRD experiments showed that the bismuth is initially present as an oxycarbonate that transforms to metastable {beta}-Bi{sub 2}O{sub 3} by 400 C. At {approx}650 C, coincident with the onset of densification, the cubic binary phase, Bi{sub 38}ZnO{sub 58} forms and remains stable to >800 C, indicating that a eutectic liquid does not form during normal varistor sintering ({approx}730 C). Finally, the formation and morphology of bismuth oxide phase regions that form on the varistors surfaces during slow cooling were studied.

  9. High temperature aircraft research furnace facilities

    Science.gov (United States)

    Smith, James E., Jr.; Cashon, John L.

    1992-01-01

    Focus is on the design, fabrication, and development of the High Temperature Aircraft Research Furnace Facilities (HTARFF). The HTARFF was developed to process electrically conductive materials with high melting points in a low gravity environment. The basic principle of operation is to accurately translate a high temperature arc-plasma gas front as it orbits around a cylindrical sample, thereby making it possible to precisely traverse the entire surface of a sample. The furnace utilizes the gas-tungsten-arc-welding (GTAW) process, also commonly referred to as Tungsten-Inert-Gas (TIG). The HTARFF was developed to further research efforts in the areas of directional solidification, float-zone processing, welding in a low-gravity environment, and segregation effects in metals. The furnace is intended for use aboard the NASA-JSC Reduced Gravity Program KC-135A Aircraft.

  10. Fundamental aspects of high-temperature corrosion

    OpenAIRE

    Rapp, Robert

    1993-01-01

    Some recent considerations in three widely different aspects of high-temperature corrosion are summarized: 1) reactions at the metal/scale interface in support of scale growth; 2) mass transfer effects in the control of evaporation of volatile reaction products; and 3) the codeposition of multiple elements for diffusion coatings using halide-activated cementation packs. The climb of misfit edge dislocations from the metal/scale interface can achieve the annihilation of vacancies associated wi...

  11. Measurement of thermodynamic temperature of high temperature fixed points

    Energy Technology Data Exchange (ETDEWEB)

    Gavrilov, V. R.; Khlevnoy, B. B.; Otryaskin, D. A.; Grigorieva, I. A.; Samoylov, M. L.; Sapritsky, V. I. [All-Russian Research Institute for Optical and Physical Measurements (VNIIOFI), 46 Ozernaya St., Moscow 119361 (Russian Federation)

    2013-09-11

    The paper is devoted to VNIIOFI's measurements of thermodynamic temperature of the high temperature fixed points Co-C, Pt-C and Re-C within the scope of the international project coordinated by the Consultative Committee for Thermometry working group 5 'Radiation Thermometry'. The melting temperatures of the fixed points were measured by a radiance mode radiation thermometer calibrated against a filter radiometer with known irradiance spectral responsivity via a high temperature black body. This paper describes the facility used for the measurements, the results and estimated uncertainties.

  12. Measurement of thermodynamic temperature of high temperature fixed points

    Science.gov (United States)

    Gavrilov, V. R.; Khlevnoy, B. B.; Otryaskin, D. A.; Grigorieva, I. A.; Samoylov, M. L.; Sapritsky, V. I.

    2013-09-01

    The paper is devoted to VNIIOFI's measurements of thermodynamic temperature of the high temperature fixed points Co-C, Pt-C and Re-C within the scope of the international project coordinated by the Consultative Committee for Thermometry working group 5 "Radiation Thermometry". The melting temperatures of the fixed points were measured by a radiance mode radiation thermometer calibrated against a filter radiometer with known irradiance spectral responsivity via a high temperature black body. This paper describes the facility used for the measurements, the results and estimated uncertainties.

  13. Temperature effects in photodynamic processes

    Science.gov (United States)

    Hovhannisyan, Vladimir A.; Avetisyan, Hasmik A.; Mathevosyan, Margarita B.; Elbakyan, Egishe G.

    2005-04-01

    Photodynamic activity of several dyes on Drosophila melanogaster at different temperatures (15-35°C) inside of test-tubes was investigated. Both phototoxic sensitizers (chlorin e6, methylene blue, etc. -group A) and non active compounds (hemoglobin, brilliant green, pyronine, etc.-group B) were used. Dyes of 10-5-10-3 M concentration were added to the food for drosophila 24 hours before irradiation. Solar radiation, narrow-band halogen lamps, LEDs and laser were used as a photo-stimulator. Irradiation parameters: I dyes in the control test-tubes at all doses of irradiation and temperatures applied percentage of survived insects was approximately 100%. In the darkness with the use of all dyes observations also indicated no damage to the insects. At the temperatures up to 25°C when using dyes of group B insects were not affected at all, while with the dyes of group A findings showed dose-dependent insect mortality. At high temperatures (30-35°C) when using group B dyes flies were losing their mobility and in the case of group A dyes the drosophila"s survival value sharply dropped. Combination of dyes from A group with some dyes from B group leads to the partial disappearance of photodynamic effect. This, probably, is concerned with the toxic photoproduct suppression by the inactive dye. Experimental model of drosophila allows to investigate photosensitization impact within wide temperature range, to find out the processes, when using combination of dyes, as well as to study photodynamic effect on reproductive functions of insects.

  14. (Krauss) at constant high temperatures

    African Journals Online (AJOL)

    A number of opinions are held on the relative importance of the various physical ... optimum as well as extreme temperatures on vital functions such as survival, egg ..... solids on the biology of certain freshwater molluscs. D .Sc. thesis,. Potch.

  15. High temperature superconductors applications in telecommunications

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A.A.; Li, J.; Zhang, M.F. [Prairie View A& M Univ., Texas (United States)

    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.

  16. Body Temperature Controlled Optical and Thermal Information Storage Light Scattering Display with Fluorescence Effect and High Mechanical Strength.

    Science.gov (United States)

    Chen, Si; Tong, Xiaoqian; He, Huiwen; Ma, Meng; Shi, Yanqin; Wang, Xu

    2017-04-05

    A kind of body temperature controlled optical and thermal information storage light scattering display based on super strong liquid crystalline physical gel with special "loofah-like gel network" was successfully prepared. Such liquid crystal (LC) gel was obtained by mixing a dendritic gelator (POSS-G1-BOC), an azobenzene compound (2Azo2), and a phosphor tethered liquid crystalline host (5CB), which could show its best contrast ratio at around human body temperature under UV light because of the phosphor's fluorescence effect. The gel also has quite strong mechanical strength, which could be used in wearable device field especially under sunlight, even under the forcing conditions as harsh as being centrifuged for 10 min at the speed of 2000 r/min. The whole production process of such a display is quite simple and could lead to displays at any size through noncontact writing. We believe it will have wide applications in the future.

  17. Thermal effects of planar high temperature heat pipes in solid oxide cell stacks operated with internal methane reforming

    Science.gov (United States)

    Dillig, Marius; Plankenbühler, Thomas; Karl, Jürgen

    2018-01-01

    The presented paper contributes to developing a new thermal control approach for solid oxide cell (SOC) stacks and systems. Integrating planar liquid metal heat pipes to the interconnector structure of the stacks targets a reduction of internal temperature gradients and an enhanced heat extraction from the stack. This work applies 3-D CFD-modelling to discuss the thermal effects of integrated heat pipes in solid oxide cell stacks, in order to evaluate the possible benefits in terms of temperature gradient reduction and heat removal as well as the resulting benefits for stacks and systems. The stack model set-up is described and its functioning is validated with experimental results from thermal short stack measurements with integrated heat pipe interconnectors. The simulation results are discussed with respect to the possible benefits for full-scale stacks of different cell size, in particular regarding internal heat recycling and the beneficial reduction of air ratios.

  18. High temperature superconducting fault current limiter

    Science.gov (United States)

    Hull, John R.

    1997-01-01

    A fault current limiter (10) for an electrical circuit (14). The fault current limiter (10) includes a high temperature superconductor (12) in the electrical circuit (14). The high temperature superconductor (12) is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter (10).

  19. Technological Evolution of High Temperature Superconductors

    Science.gov (United States)

    2015-12-01

    TEMPERATURE SUPERCONDUCTORS by Jordan R. White December 2015 Thesis Advisor: Clifford Whitcomb Co-Advisor: Fotis Papoulias THIS PAGE INTENTIONALLY...AND SUBTITLE TECHNOLOGICAL EVOLUTION OF HIGH TEMPERATURE SUPERCONDUCTORS 5. FUNDING NUMBERS 6. AUTHOR(S) Jordan R. White 7. PERFORMING ORGANIZATION...trends. 14. SUBJECT TERMS electric ships, high temperature superconductor , HTS 15. NUMBER OF PAGES 111 16. PRICE CODE 17. SECURITY CLASSIFICATION

  20. FT-IR analysis of high temperature annealing effects in a-SiC:H thin films

    Science.gov (United States)

    Frischmuth, Tobias; Schneider, Michael; Grille, Thomas; Schmid, U.

    2017-06-01

    Hydrogenated amorphous SiC (a-SiC:H) is an attractive material for MEMS applications where high robustness or operation in harsh environments is targeted. In previous publications, it was demonstrated, that the properties of a-SiC:H thin films can be tailored over a wide range by changing the auxiliary table excitation power of a dual plasma source deposition process using an inductively coupled plasma-enhanced chemical vapour deposition system. In this work, the annealing behavior of dual plasma source deposited a-SiC:H thin films under argon atmosphere is investigated by using Fourier transform infrared (FT-IR) spectroscopy for chemical analysis. All investigated layers show a decrease of hydrogen containing bonds (X-Hx) and an increase of Si-C bonds with increasing annealing temperature in the FT-IR spectrum. This behaviour is directly linked to the effusion of hydrogen from the thin films at elevated temperatures. In addition, films deposited at higher auxiliary plasma power show more X-Hx and less Si-C bonds, indicating a higher hydrogen amount in those films. All layers shrink with increasing annealing temperature due to the effusion of hydrogen with a stronger shrink at higher PT values caused by the increased hydrogen amount. This shrink also leads to a densification of the thin films.

  1. Energy storage via high temperature superconductivity (SMES)

    Energy Technology Data Exchange (ETDEWEB)

    Mikkonen, R. [Tampere Univ. of Technology (Finland)

    1998-10-01

    The technology concerning high temperature superconductors (HTS) is matured to enabling different kind of prototype applications including SMES. Nowadays when speaking about HTS systems, attention is focused on the operating temperature of 20-30 K, where the critical current and flux density are fairly close to 4.2 K values. In addition by defining the ratio of the energy content of a novel HTS magnetic system and the required power to keep the system at the desired temperature, the optimum settles to the above mentioned temperature range. In the frame of these viewpoints a 5 kJ HTS SMES system has been designed and tested at Tampere University of Technology with a coil manufactured by American Superconductor (AMSC). The HTS magnet has inside and outside diameters of 252 mm and 317 mm, respectively and axial length of 66 mm. It operates at 160 A and carries a total of 160 kA-turns to store the required amount of energy. The effective magnetic inductance is 0.4 H and the peak axial field is 1.7 T. The magnet is cooled to the operating temperature of 20 K with a two stage Gifford-McMahon type cryocooler with a cooling power of 60 W at 77 K and 8 W at 20 K. The magnetic system has been demonstrated to compensate a short term loss of power of a sensitive consumer

  2. Effect of High Temperature Storage in Vacuum, Air, and Humid Conditions on Degradation of Gold/Aluminum Wire Bonds in PEMs

    Science.gov (United States)

    Teverovsky, Alexander

    2006-01-01

    Microcircuits encapsulated in three plastic package styles were stored in different environments at temperatures varying from 130 C to 225 C for up to 4,000 hours in some cases. To assess the effect of oxygen, the parts were aged at high temperatures in air and in vacuum chambers. The effect of humidity was evaluated during long-term highly accelerated temperature and humidity stress testing (HAST) at temperatures of 130 C and 150 C. High temperature storage testing of decapsulated microcircuits in air, vacuum, and HAST chambers was carried out to evaluate the role of molding compounds in the environmentally-induced degradation and failure of wire bonds (WB). This paper reports on accelerating factors of environment and molding compound on WB failures. It has been shown that all environments, including oxygen, moisture, and the presence of molding compounds reduce time-to-failures compared to unencapsulated devices in vacuum conditions. The mechanism of the environmental effect on KB degradation is discussed.

  3. Effects of melatonin and green-wavelength LED light on the physiological stress and immunity of goldfish, Carassius auratus, exposed to high water temperature.

    Science.gov (United States)

    Jung, Seo Jin; Kim, Na Na; Choi, Young Jae; Choi, Ji Yong; Choi, Young-Ung; Heo, Youn Seong; Choi, Cheol Young

    2016-10-01

    This study investigated the effects of increasing water temperature (22-30 °C) on the physiological stress response and immunity of goldfish, Carassius auratus, and the ability of green light-emitting diode (LED) irradiation or melatonin injections to mitigate this temperature-induced stress. To evaluate the effects of either green-wavelength LED light or melatonin on stress in goldfish, we measured plasma triiodothyronine (T3), thyroxine (T4), and thyroid hormone receptor (TR) mRNA expression; plasma cortisol and glucose; and immunoglobulin M (IgM) and lysozyme mRNA expression. The thyroid hormone activities, TR mRNA expression, and plasma cortisol and glucose were higher in goldfish exposed to high-temperature water, but were lower after exposure to melatonin or green-wavelength LED light. Lysozyme mRNA expression and plasma IgM activity and protein expression were lower after exposure to high water temperatures and higher after melatonin or green-wavelength LED light treatments. Therefore, high water temperature induced stress and decreased immunity; however, green-wavelength LED light and melatonin treatments mitigated the effects of stress and enhanced immunity. The benefits of melatonin decreased with time, whereas those of green-wavelength LED treatment did not.

  4. Effects of several types of biomass fuels on the yield, nanostructure and reactivity of soot from fast pyrolysis at high temperatures

    DEFF Research Database (Denmark)

    Trubetskaya, Anna; Jensen, Peter Arendt; Jensen, Anker Degn

    2016-01-01

    This study presents the effect of biomass origin on the yield, nanostructure and reactivity of soot. Soot was produced from wood and herbaceous biomass pyrolysis at high heating rates and at temperatures of 1250 and 1400 °C in a drop tube furnace. The structure of solid residues was characterized...

  5. Deep Trek High Temperature Electronics Project

    Energy Technology Data Exchange (ETDEWEB)

    Bruce Ohme

    2007-07-31

    This report summarizes technical progress achieved during the cooperative research agreement between Honeywell and U.S. Department of Energy to develop high-temperature electronics. Objects of this development included Silicon-on-Insulator (SOI) wafer process development for high temperature, supporting design tools and libraries, and high temperature integrated circuit component development including FPGA, EEPROM, high-resolution A-to-D converter, and a precision amplifier.

  6. High Temperature Fluoride Salt Test Loop

    Energy Technology Data Exchange (ETDEWEB)

    Aaron, Adam M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cunningham, Richard Burns [Univ. of Tennessee, Knoxville, TN (United States); Fugate, David L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Holcomb, David Eugene [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kisner, Roger A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Peretz, Fred J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Robb, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wilson, Dane F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yoder, Jr, Graydon L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-12-01

    Effective high-temperature thermal energy exchange and delivery at temperatures over 600°C has the potential of significant impact by reducing both the capital and operating cost of energy conversion and transport systems. It is one of the key technologies necessary for efficient hydrogen production and could potentially enhance efficiencies of high-temperature solar systems. Today, there are no standard commercially available high-performance heat transfer fluids above 600°C. High pressures associated with water and gaseous coolants (such as helium) at elevated temperatures impose limiting design conditions for the materials in most energy systems. Liquid salts offer high-temperature capabilities at low vapor pressures, good heat transport properties, and reasonable costs and are therefore leading candidate fluids for next-generation energy production. Liquid-fluoride-salt-cooled, graphite-moderated reactors, referred to as Fluoride Salt Reactors (FHRs), are specifically designed to exploit the excellent heat transfer properties of liquid fluoride salts while maximizing their thermal efficiency and minimizing cost. The FHR s outstanding heat transfer properties, combined with its fully passive safety, make this reactor the most technologically desirable nuclear power reactor class for next-generation energy production. Multiple FHR designs are presently being considered. These range from the Pebble Bed Advanced High Temperature Reactor (PB-AHTR) [1] design originally developed by UC-Berkeley to the Small Advanced High-Temperature Reactor (SmAHTR) and the large scale FHR both being developed at ORNL [2]. The value of high-temperature, molten-salt-cooled reactors is also recognized internationally, and Czechoslovakia, France, India, and China all have salt-cooled reactor development under way. The liquid salt experiment presently being developed uses the PB-AHTR as its focus. One core design of the PB-AHTR features multiple 20 cm diameter, 3.2 m long fuel channels

  7. Electrochemical high-temperature gas sensors

    Science.gov (United States)

    Saruhan, B.; Stranzenbach, M.; Yüce, A.; Gönüllü, Y.

    2012-06-01

    Combustion produced common air pollutant, NOx associates with greenhouse effects. Its high temperature detection is essential for protection of nature. Component-integration capable high-temperature sensors enable the control of combustion products. The requirements are quantitative detection of total NOx and high selectivity at temperatures above 500°C. This study reports various approaches to detect NO and NO2 selectively under lean and humid conditions at temperatures from 300°C to 800°C. All tested electrochemical sensors were fabricated in planar design to enable componentintegration. We suggest first an impedance-metric gas sensor for total NOx-detection consisting of NiO- or NiCr2O4-SE and PYSZ-electrolyte. The electrolyte-layer is about 200μm thickness and constructed of quasi-single crystalline columns. The sensing-electrode (SE) is magnetron sputtered thin-layers of NiO or NiCr2O4. Sensor sensitivity for detection of total NOx has been measured by applying impedance analysis. The cross-sensitivity to other emission gases such as CO, CO2, CH4 and oxygen (5 vol.%) has been determined under 0-1000ppm NO. Sensor maintains its high sensitivity at temperatures up to 550°C and 600°C, depending on the sensing-electrode. NiO-SE yields better selectivity to NO in the presence of oxygen and have shorter response times comparing to NiCr2O4-SE. For higher temperature NO2-sensing capability, a resistive DC-sensor having Al-doped TiO2-sensing layers has been employed. Sensor-sensitivity towards NO2 and cross-sensitivity to CO has been determined in the presence of H2O at temperatures 600°C and 800°C. NO2 concentrations varying from 25 to 100ppm and CO concentrations from 25 to 75ppm can be detected. By nano-tubular structuring of TiO2, NO2 sensitivity of the sensor was increased.

  8. Effects of short-term high temperature on grain quality and starch granules of rice (Oryza sativa L.) at post-anthesis stage.

    Science.gov (United States)

    Chen, Jianlin; Tang, Liang; Shi, Peihua; Yang, Baohua; Sun, Ting; Cao, Weixing; Zhu, Yan

    2017-03-01

    High temperature causes negative effects on grain yield and quality of rice (Oryza sativa L.). In this study, the effects of short-term high temperature (SHT) on grain quality and starch granules were investigated in two rice cultivars Nanjing 41 (NJ41, heat-sensitive) and Wuxiangjing 14 (WJ14, heat-tolerant) at post-anthesis stage (anthesis and early grain-filling stage). The results of rice quality analysis showed that chalky rate and chalkiness increased while brown rice rate, milled rice rate, and head rice rate decreased in two rice cultivars with the increase of high temperature and prolonged duration. Moreover, SHT stress reduced the accumulation of amylose as well as starch accumulation. The starch accumulation and eating quality were more sensitive to SHT than the appearance and milling quality. The starch structure data observed by scanning electron microscope further showed that the starch granules are arranged loosely and more single starch granules appeared after SHT treatment. The extent of change in rice quality and starch traits of WJ14 under SHT was lower than that of NJ41. The effects of SHT at anthesis stage were greater than that at grain-filling stage. Taken together, the results could help further understand the physiological and biochemical processes governing rice quality under high-temperature conditions.

  9. Separating effective high density polyethylene segments from olefin block copolymers using high temperature liquid chromatography with a preloaded discrete adsorption promoting solvent barrier.

    Science.gov (United States)

    Chatterjee, Tirtha; Rickard, Mark A; Pearce, Eric; Pangburn, Todd O; Li, Yongfu; Lyons, John W; Cong, Rongjuan; deGroot, A Willem; Meunier, David M

    2016-09-23

    Recent advances in catalyst technology have enabled the synthesis of olefin block copolymers (OBC). One type is a "hard-soft" OBC with a high density polyethylene (HDPE) block and a relatively low density polyethylene (VLDPE) block targeted as thermoplastic elastomers. Presently, one of the major challenges is to fractionate HDPE segments from the other components in an experimental OBC sample (block copolymers and VLDPE segments). Interactive high temperature liquid chromatography (HTLC) is ineffective for OBC separation as the HDPE segments and block copolymer chains experience nearly identical enthalpic interactions with the stationary phase and co-elute. In this work we have overcome this challenge by using liquid chromatography under the limiting conditions of desorption (LC LCD). A solvent plug (discrete barrier) is introduced in front of the sample which specifically promotes the adsorption of HDPE segments on the stationary phase (porous graphitic carbon). Under selected thermodynamic conditions, VLDPE segments and block copolymer chains crossed the barrier while HDPE segments followed the pore-included barrier solvent and thus enabled separation. The barrier solvent composition was optimized and the chemical composition of fractionated polymer chains was investigated as a function of barrier solvent strength using an online Fourier-transform infrared (FTIR) detector. Our study revealed that both the HDPE segments as well as asymmetric block copolymer chains (HDPE block length≫VLDPE block length) are retained in the separation and the barrier strength can be tailored to retain a particular composition. At the optimum barrier solvent composition, this method can be applied to separate effective HDPE segments from the other components, which has been demonstrated using an experimental OBC sample. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Thermoelastic properties of minerals at high temperature

    Indian Academy of Sciences (India)

    under high temperatures and calculated the second-order elastic constant (Cij ) and bulk modulus. (KT) of the above minerals, in two cases first by taking Anderson–Gruneisen parameter (δT) as temperature-independent and then by treating δT as temperature-dependent parameter. The results obtained when δT is ...

  11. High Temperature Capacitors for Venus Exploration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this SBIR program, TRS Technologies has developed several new dielectrics for high temperature applications including signal conditioning, filtering and energy...

  12. Advances in high temperature chemistry 1

    CERN Document Server

    Eyring, Leroy

    2013-01-01

    Advances in High Temperature Chemistry, Volume 1 describes the complexities and special and changing characteristics of high temperature chemistry. After providing a brief definition of high temperature chemistry, this nine-chapter book goes on describing the experiments and calculations of diatomic transition metal molecules, as well as the advances in applied wave mechanics that may contribute to an understanding of the bonding, structure, and spectra of the molecules of high temperature interest. The next chapter provides a summary of gaseous ternary compounds of the alkali metals used in

  13. High temperature phase equilibria and phase diagrams

    CERN Document Server

    Kuo, Chu-Kun; Yan, Dong-Sheng

    2013-01-01

    High temperature phase equilibria studies play an increasingly important role in materials science and engineering. It is especially significant in the research into the properties of the material and the ways in which they can be improved. This is achieved by observing equilibrium and by examining the phase relationships at high temperature. The study of high temperature phase diagrams of nonmetallic systems began in the early 1900s when silica and mineral systems containing silica were focussed upon. Since then technical ceramics emerged and more emphasis has been placed on high temperature

  14. High-Temperature Test Technology

    Science.gov (United States)

    1987-03-01

    Do any of your facilities have vacuum test capability? YesO No~l If yes, What is the minimum vacuum chamber pressure? What is the maximum allowable...available? YesO N[-- If "yes," please Indicate the following: Vaporizer Superheater Capacity Capacity Max Temperature LH2 LN2 Are gaseous hydrogen...personnel safety? 5. Does the facility have radiant heating capability? YesO NoF- If "yes," please provide the following information: Lamp types Tungsten

  15. Thermodynamics of High Temperature Materials.

    Science.gov (United States)

    1985-03-15

    temperatures In the present range have also been obtained by Krauss and Warncke [8] and by Vollmer et al. [9], using adiabatic calorimetry, and by Kollie [10...value for heat capacity. The electrical resistivity results reported by Kollie [10] and by Powell et al. [13] are respectively about 1 and 1.5% lower...extensive annealing of the specimens used in the measurements: the specimen (>99.89% pure) used by Kollie was annealed at 1100 K for 24 h and Laubitz et al

  16. High temperature inorganic membranes for separating hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Fain, D.E.; Roettger, G.E. [Oak Ridge K-25 Site, TN (United States)

    1995-08-01

    Effort has continued to accumulate data on the transport of gases over the temperature range from room temperature to 275{degrees}C with inorganic membranes having a range of pore radii from approximately 0.25 nm to 3 mn. An experimental alumina membrane having an estimated mean pore radius of 0.25 nm has been fabricated and tested. Extensive testing of this membrane indicated that the separation factor for helium and carbon tetrafluoride at 250{degrees}C was 59 and the extrapolated high temperature separation factor was 1,193. For safety reasons, earlier flow measurements concentrated on helium, carbon dioxide, and carbon tetrafluoride. New data have been acquired with hydrogen to verify the agreement with the other gases. During the measurements with hydrogen, it was noted that a considerable amount of moisture was present in the test gas. The source of this moisture and its effect on permeance was examined. Improvements were implemented to the flow test system to minimize the water content of the hydrogen test gas, and subsequent flow measurements have shown excellent results with hydrogen. The extrapolation of separation factors as a function of temperature continues to show promise as a means of using the hard sphere model to determine the pore size of membranes. The temperature dependence of helium transport through membranes appears to be considerably greater than other gases for the smallest pore sizes. The effort to extend temperature dependence to the hard sphere model continues to be delayed, primarily because of a lack of adequate adsorption data.

  17. Effect of season and high ambient temperature on activity levels and patterns of grizzly bears (Ursus arctos).

    Science.gov (United States)

    McLellan, Michelle L; McLellan, Bruce N

    2015-01-01

    Understanding factors that influence daily and annual activity patterns of a species provides insights to challenges facing individuals, particularly when climate shifts, and thus is important in conservation. Using GPS collars with dual-axis motion sensors that recorded the number of switches every 5 minutes we tested the hypotheses: 1. Grizzly bears (Ursus arctos) increase daily activity levels and active bout lengths when they forage on berries, the major high-energy food in this ecosystem, and 2. Grizzly bears become less active and more nocturnal when ambient temperature exceeds 20°C. We found support for hypothesis 1 with both male and female bears being active from 0.7 to 2.8 h longer in the berry season than in other seasons. Our prediction under hypothesis 2 was not supported. When bears foraged on berries on a dry, open mountainside, there was no relationship between daily maximum temperature (which varied from 20.4 to 40.1°C) and the total amount of time bears were active, and no difference in activity levels during day or night between warm (20.4-27.3°C) and hot (27.9-40.1°C) days. Our results highlight the strong influence that food acquisition has on activity levels and patterns of grizzly bears and is a challenge to the heat dissipation limitation theory.

  18. Effect of season and high ambient temperature on activity levels and patterns of grizzly bears (Ursus arctos.

    Directory of Open Access Journals (Sweden)

    Michelle L McLellan

    Full Text Available Understanding factors that influence daily and annual activity patterns of a species provides insights to challenges facing individuals, particularly when climate shifts, and thus is important in conservation. Using GPS collars with dual-axis motion sensors that recorded the number of switches every 5 minutes we tested the hypotheses: 1. Grizzly bears (Ursus arctos increase daily activity levels and active bout lengths when they forage on berries, the major high-energy food in this ecosystem, and 2. Grizzly bears become less active and more nocturnal when ambient temperature exceeds 20°C. We found support for hypothesis 1 with both male and female bears being active from 0.7 to 2.8 h longer in the berry season than in other seasons. Our prediction under hypothesis 2 was not supported. When bears foraged on berries on a dry, open mountainside, there was no relationship between daily maximum temperature (which varied from 20.4 to 40.1°C and the total amount of time bears were active, and no difference in activity levels during day or night between warm (20.4-27.3°C and hot (27.9-40.1°C days. Our results highlight the strong influence that food acquisition has on activity levels and patterns of grizzly bears and is a challenge to the heat dissipation limitation theory.

  19. The Effect of Composition on the Surface Finish of PS400: A New High Temperature Solid Lubricant Coating

    Science.gov (United States)

    DellaCorte, Christopher; Stanford, malcolm K.; Thomas, Fransua; Edmonds, Brian J.

    2010-01-01

    A new composite, multi-constituent, solid lubricant coating, NASA PS400, developed for high temperature tribological applications, exhibits a smoother surface finish after grinding and polishing than its predecessors PS200 and PS300. In this paper, the baseline composition of PS400 is modified to investigate each individual constituent s role on the achievable surface finish through a series of coating deposition, grinding, and polishing experiments. Furthermore, to explore the limits of compositional tailoring for improved tribological performance, several PS400 coatings were doped with additional solid lubricants (graphite, MoS2 and BN) and tribologically tested. The test results clearly showed that, compared to PS300 coatings, PS400 achieves a smoother surface finish via a reduced lubricant content. Coatings prepared with higher than the baseline level (10 wt%) of lubricants exhibited higher final surface roughness than the earlier generation PS300 coatings. Reducing or eliminating the one or both lubricants (fluorides or silver) did not further improve the surface finish suggesting that the current composition of PS400 is near optimal with respect to surface finish. Lastly, attempts to improve the poor initial room temperature tribological behavior of PS400 via the addition of traditional solid lubricants were unsuccessful. Based upon this work and earlier results it is expected that future research will concentrate on developing methods to produce a lubricious glaze on the rubbing surface during break in to ensure that low friction and wear are rapidly achieved.

  20. Effect of temperature on AOB activity of a partial nitritation SBR treating landfill leachate with extremely high nitrogen concentration.

    Science.gov (United States)

    Gabarró, J; Ganigué, R; Gich, F; Ruscalleda, M; Balaguer, M D; Colprim, J

    2012-12-01

    This study investigates the effects of temperature on ammonia oxidizing bacteria activity in a partial nitritation (PN) sequencing batch reactor. Stable PN was achieved in a 250 L SBR with a minimum operating volume of 111L treating mature landfill leachate containing an ammonium concentration of around 6000 mg N-NH(4)(+)L(-1) at both 25 and 35 °C. A suitable influent to feed an anammox reactor was achieved in both cases. A kinetic model was applied to study the influence of free ammonia (FA), the free nitrous acid (FNA) inhibition, and the inorganic carbon (IC) limitation. NH(4)(+) and NO(2)(-) concentrations were similar at 25 and 35 °C experiments (about 2500 mg N-NH(4)(+)L(-1) and 3500 mg N-NO(2)(-)L(-1)), FA and FNA concentrations differed due to the strong temperature dependence. FNA was the main source of inhibition at 25 °C, while at 35 °C combined FA and FNA inhibition occurred. DGGE results demonstrated that PN-SBR sludge was enriched on the same AOB phylotypes in both experiments. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Creep behavior of alloy 617 in high temperature air and helium environments-effect of oxidation damage

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Chang Heui; Kim, Sung Hwan [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Sah, Injin; Kim, Dae Jong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    The creep behavior of a nickel-base superalloy, Alloy 617, which is considered as a candidate material for the very high temperature gas cooled reactor, was studied. Creep rupture tests were carried out at 800°C, 900°C and 1000°C in static and flowing helium environments as well as in air. Creep rupture life in static helium was longer than that in air, while it was shorter in flowing helium environments. Microstructure observation of the creep tested specimens showed that the shorter creep rupture life in flowing helium was associated with the thicker oxide layer, greater decarburization depth, and deeper internal oxidation happened during the creep tests. The degree of such oxidation damage was quantified for the creep tested specimens and correlated with the creep rupture life in different environments.

  2. Different effects of night versus day high temperature on rice quality and accumulation profiling of rice grain proteins during grain filling.

    Science.gov (United States)

    Li, Haixia; Chen, Zhen; Hu, Meixia; Wang, Zhenmei; Hua, Hua; Yin, Changxi; Zeng, Hanlai

    2011-09-01

    High temperature has adverse effects on rice yield and quality. The different influences of night high temperature (NHT) and day high temperature (DHT) on rice quality and seed protein accumulation profiles during grain filling in indica rice '9311' were studied in this research. The treatment temperatures of the control, NHT, and DHT were 28°C/20°C, 27°C/35°C, and 35°C/27°C, respectively, and all the treatments were maintained for 20 days. The result of rice quality analysis indicated that compared with DHT, NHT exerted less effect on head rice rate and chalkiness, whereas greater effect on grain weight. Moreover, the dynamic accumulation change profiles of 61 protein spots, differentially accumulated and successfully identified under NHT and DHT conditions, were performed by proteomic approach. The results also showed that the different suppressed extent of accumulation amount of cyPPDKB might result in different grain chalkiness between NHT and DHT. Most identified isoforms of proteins, such as PPDK and pullulanase, displayed different accumulation change patterns between NHT and DHT. In addition, compared with DHT, NHT resulted in the unique accumulation patterns of stress and defense proteins. Taken together, the mechanisms of seed protein accumulation profiles induced by NHT and DHT during grain filling should be different in rice, and the potential molecular basis is discussed in this study.

  3. Diamond based detectors for high temperature, high radiation environments

    Science.gov (United States)

    Metcalfe, A.; Fern, G. R.; Hobson, P. R.; Smith, D. R.; Lefeuvre, G.; Saenger, R.

    2017-01-01

    Single crystal CVD diamond has many desirable properties as a radiation detector; exceptional radiation hardness and physical hardness, chemical inertness, low Z (close to human tissue, good for dosimetry and transmission mode applications), wide bandgap (high temperature operation with low noise and solar blind), an intrinsic pathway to fast neutron detection through the 12C(n,α)9Be reaction. This combination of radiation hardness, temperature tolerance and ability to detect mixed radiation types with a single sensor makes diamond particularly attractive as a detector material for harsh environments such as nuclear power station monitoring (fission and fusion) and oil well logging. Effective exploitation of these properties requires the development of a metallisation scheme to give contacts that remain stable over extended periods at elevated temperatures (up to 250°C in this instance). Due to the cost of the primary detector material, computational modelling is essential to best utilise the available processing methods for optimising sensor response through geometry and conversion media configurations and to fully interpret experimental data. Monte Carlo simulations of our diamond based sensor have been developed, using MCNP6 and FLUKA2011, assessing the sensor performance in terms of spectral response and overall efficiency as a function of the detector and converter geometry. Sensors with varying metallisation schemes for high temperature operation have been fabricated at Brunel University London and by Micron Semiconductor Limited. These sensors have been tested under a varied set of conditions including irradiation with fast neutrons and alpha particles at high temperatures. The presented study indicates that viable metallisation schemes for high temperature contacts have been successfully developed and the modelling results, supported by preliminary experimental data from partners, indicate that the simulations provide a reasonable representation of

  4. Effect of ambient temperature on viral replication and serum antibody titers following administration of a commercial intranasal modified-live infectious bovine rhinotracheitis-parainfluenza-3 virus vaccine to beef cattle housed in high- and moderate-ambient temperature environments.

    Science.gov (United States)

    Grissett, Gretchen P; White, Brad J; Anderson, David E; Larson, Robert E; Miesner, Matt D

    2014-12-01

    To evaluate the effect of ambient temperature on viral replication and serum antibody titers following administration of an intranasal modified-live infectious bovine rhinotracheitis (IBR)-parainfluenza-3 (PI3) virus vaccine to beef calves housed in high- (> 32°C) and moderate- (21°C) ambient temperature environments. 28 calves (mean weight, 206.8 kg). Calves were randomly allocated to 4 treatment groups (housed outdoors during high ambient temperature with [HAT; n = 10] or without [HAC; 4] vaccination or housed indoors in a moderate ambient temperature with [MAT; 10] or without [MAC; 4] vaccination). Rectal and nasal mucosal temperatures were recorded every 2 hours from 8 AM to 8 PM on days 0 (vaccination) and 1. Nasal swab specimens were obtained on days 0 through 7 for virus isolation. Serum samples were collected on days 0, 7, 14, and 28 for determination of antibody titers. Mean rectal temperature did not differ among the treatment groups. Mean nasal temperature for the HAT group was significantly higher than that for the MAT group at 6, 24, 30, 32, and 38 hours after vaccination. Viable IBR virus was isolated from all vaccinated calves on days 1 through 6. Two weeks after vaccination, vaccinated calves had anti-IBR antibody titers that were significantly greater than those for unvaccinated calves. Mean anti-IBR antibody titers did not differ significantly between the HAT and MAT groups. Results indicated that, following vaccination with an intranasal modified-live IBR-PI3 virus vaccine, IBR viral replication and serum antibody titers did not differ significantly between calves housed in high- and moderate-ambient temperature environments.

  5. High temperature skin friction measurement

    Science.gov (United States)

    Tcheng, Ping; Holmes, Harlan K.; Supplee, Frank H., Jr.

    1989-01-01

    Skin friction measurement in the NASA Langley hypersonic propulsion facility is described. The sensor configuration utilized an existing balance, modified to provide thermal isolation and an increased standoff distance. For test run times of about 20 sec and ambient-air cooling of the test section and balance, the modified balance performed satisfactorily, even when it was subjected to acoustic and structural vibration. The balance is an inertially balanced closed-loop servo system where the current to a moving-coil motor needed to restore or null the output from the position sensor is a measure of the force or skin friction tending to displace the moving element. The accuracy of the sensor is directly affected by the position sensor in the feedback loop, in this case a linear-variable differential transformer which has proven to be influenced by temperature gradients.

  6. Effect of Fast Pyrolysis Conditions on the Biomass Solid Residues at High Temperatures (1000-1400°C)

    DEFF Research Database (Denmark)

    Trubetskaya, Anna; Jensen, Anker D.; Jensen, Peter Arendt

    to the parental fuel, whereas alfalfa straw char particle size remained unaltered with the higher temperatures. In this study, the retained shape of beechwood and herbaceous biomass samples is related to the presence of extractives and formation of silicates. Soot yield from herbaceous fuels occurs lower than...... and morphology. Scanning electron microscopy (SEM/EDS), elementary analysis, CAMSIZER XT, ash compositional analysis were applied to characterize the effect of operational conditions on the solid and gas products. Char yield from fast pyrolysis in the DFT setup was 2 to 6 % (daf) lower than in the WMR apparatus....... During fast pyrolysis pinewood underwent drastic morphological transformations, whereas beechwood and straw samples retained the original porous structure of the parental fuel with the slight melting on the surface. Particle size of Danish wheat straw char decreases in a half-width with respect...

  7. The influence of temperature dynamics and dynamic finite ion Larmor radius effects on seeded high amplitude plasma blobs

    DEFF Research Database (Denmark)

    Held, Magnus; Wiesenberger, M.; Madsen, Jens

    2016-01-01

    Thermal effects on the perpendicular convection of seeded pressure blobs in the scrape-off layer of magnetised fusion plasmas are investigated. Our numerical study is based on a four field full-F gyrofluid model, which entails the consistent description of high fluctuation amplitudes and dynamic...

  8. High Temperature Materials Laboratory third annual report

    Energy Technology Data Exchange (ETDEWEB)

    Tennery, V.J.; Foust, F.M.

    1990-12-01

    The High Temperature Materials Laboratory has completed its third year of operation as a designated DOE User Facility at the Oak Ridge National Laboratory. Growth of the user program is evidenced by the number of outside institutions who have executed user agreements since the facility began operation in 1987. A total of 88 nonproprietary agreements (40 university and 48 industry) and 20 proprietary agreements (1 university, 19 industry) are now in effect. Sixty-eight nonproprietary research proposals (39 from university, 28 from industry, and 1 other government facility) and 8 proprietary proposals were considered during this reporting period. Research projects active in FY 1990 are summarized.

  9. The influence of temperature dynamics and dynamic finite ion Larmor radius effects on seeded high amplitude plasma blobs

    DEFF Research Database (Denmark)

    Held, Magnus; Wiesenberger, M.; Madsen, Jens

    2016-01-01

    Thermal effects on the perpendicular convection of seeded pressure blobs in the scrape-off layer of magnetised fusion plasmas are investigated. Our numerical study is based on a four field full-F gyrofluid model, which entails the consistent description of high fluctuation amplitudes and dynamic...... finite Larmor radius effects. We find that the maximal radial blob velocity increases with the square root of the initial pressure perturbation and that a finite Larmor radius contributes to highly compact blob structures that propagate in the poloidal direction. An extensive parameter study reveals...... that a smooth transition to this compact blob regime occurs when the finite Larmor radius effect strength, defined by the ratio of the magnetic field aligned component of the ion diamagnetic to the E × B vorticity, exceeds unity. The maximal radial blob velocities agree excellently with the inertial velocity...

  10. Conformal Properties in High Temperature QCD

    CERN Document Server

    Ishikawa, K -I; Nakayama, Yu; Yoshie, T

    2015-01-01

    We investigate the properties of quarks and gluons above the chiral phase transition temperature $T_c,$ using the RG improved gauge action and the Wilson quark action with two degenerate quarks mainly on a $32^3\\times 16$ lattice. In the one-loop perturbation theory, the thermal ensemble is dominated by the gauge configurations with effectively $Z(3)$ center twisted boundary conditions, making the thermal expectation value of the spatial Polyakov loop take a non-trivial $Z(3)$ center. This is in agreement with our lattice simulation of high temperature QCD. We further observe that the temporal propagator of massless quarks at extremely high temperature $\\beta=100.0 \\, (T \\simeq10^{58} T_c)$ remarkably agrees with the temporal propagator of free quarks with the $Z(3)$ twisted boundary condition for $t/L_t \\geq 0.2$, but differs from that with the $Z(3)$ trivial boundary condition. As we increase the mass of quarks $m_q$, we find that the thermal ensemble continues to be dominated by the $Z(3)$ twisted gauge fi...

  11. Effect of Carbide Dissolution on Chlorine Induced High Temperature Corrosion of HVOF and HVAF Sprayed Cr3C2-NiCrMoNb Coatings

    Science.gov (United States)

    Fantozzi, D.; Matikainen, V.; Uusitalo, M.; Koivuluoto, H.; Vuoristo, P.

    2018-01-01

    Highly corrosion- and wear-resistant thermally sprayed chromium carbide (Cr3C2)-based cermet coatings are nowadays a potential highly durable solution to allow traditional fluidized bed combustors (FBC) to be operated with ecological waste and biomass fuels. However, the heat input of thermal spray causes carbide dissolution in the metal binder. This results in the formation of carbon saturated metastable phases, which can affect the behavior of the materials during exposure. This study analyses the effect of carbide dissolution in the metal matrix of Cr3C2-50NiCrMoNb coatings and its effect on chlorine-induced high-temperature corrosion. Four coatings were thermally sprayed with HVAF and HVOF techniques in order to obtain microstructures with increasing amount of carbide dissolution in the metal matrix. The coatings were heat-treated in an inert argon atmosphere to induce secondary carbide precipitation. As-sprayed and heat-treated self-standing coatings were covered with KCl, and their corrosion resistance was investigated with thermogravimetric analysis (TGA) and ordinary high-temperature corrosion test at 550 °C for 4 and 72 h, respectively. High carbon dissolution in the metal matrix appeared to be detrimental against chlorine-induced high-temperature corrosion. The microstructural changes induced by the heat treatment hindered the corrosion onset in the coatings.

  12. The effect of pressurization path on high pressure gas forming of Ti-3Al-2.5V at elevated temperature

    Directory of Open Access Journals (Sweden)

    Liu Gang

    2015-01-01

    Full Text Available High pressure gas forming is a tubular component forming technology with pressurized gas at elevated temperature, based on QPF, HMGF and Hydroforming. This process can be used to form tube blank at lower temperatures with high energy efficiency and also at higher strain rates. With Ti-3Al-2.5V Ti-alloy tube, the potential of HPGF was studied further through experiments at the elevated temperatures of 650 ∘C and 700 ∘C. In order to know the formability of the Ti-alloy tube, tensile tests were also carried out. The results show that: at the temperatures of 650 ∘C and 700 ∘C, the flow curves exhibit the power-law constitutive relation until peak stress is reached and the deformability is suitable for the HPGF process of Ti-3Al-2.5V alloy tube. The effects of pressurization path on the corner filling process and thickness profile are obvious. The high pressure inflow process can result in temperature difference between the straight wall area and corner area, which makes the thickness profile special. Besides, with the stepped pressurization path, the more constant filling rate and better thickness profile can be obtained.

  13. High Temperature Solid State Lithium Battery Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Reliable energy systems with high energy density capable of operating at high temperatures, pressures and radiation levels are needed for certain NASA missions....

  14. Copper Alloy For High-Temperature Uses

    Science.gov (United States)

    Dreshfield, Robert L.; Ellis, David L.; Michal, Gary

    1994-01-01

    Alloy of Cu/8Cr/4Nb (numbers indicate parts by atom percent) improved over older high-temperature copper-based alloys in that it offers enhanced high temperature strength, resistance to creep, and ductility while retaining most of thermal conductivity of pure copper; in addition, alloy does not become embrittled upon exposure to hydrogen at temperatures as high as 705 degrees C. Designed for use in presence of high heat fluxes and active cooling; for example, in heat exchangers in advanced aircraft and spacecraft engines, and other high-temperature applications in which there is need for such material. High conductivity and hardness of alloy exploited in welding electrodes and in high-voltage and high-current switches and other applications in which wear poses design problem.

  15. Lightweight, High-Temperature Radiator Panels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Lightweight, high-temperature radiators are needed for future, high-efficiency power conversion systems for Nuclear Electric Propulsion (NEP). Creare has developed...

  16. High Temperature Rechargeable Battery Development Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This small business innovation research is intended to develop and proof the concept of a highly efficient, high temperature rechargeable battery for supporting...

  17. Effects of High-Temperature Annealing in Air on Hi-Nicalon Fiber-Reinforced Celsian Matrix Composites

    Science.gov (United States)

    Bansal, Narottam P.

    2008-01-01

    BN/SiC-coated Hi-Nicalon fiber-reinforced celsian matrix composites (CMC) were annealed for 100 h in air at various temperatures to 1200 C, followed by flexural strength measurements at room temperature. Values of yield stress and strain, ultimate strength, and composite modulus remain almost unchanged for samples annealed up to 1100 C. A thin porous layer formed on the surface of the 1100 C annealed sample and its density decreased from 3.09 to 2.90 g/cu cm. The specimen annealed at 1200 C gained 0.43 wt%, was severely deformed, and was covered with a porous layer of thick shiny glaze which could be easily peeled off. Some gas bubbles were also present on the surface. This surface layer consisted of elongated crystals of monoclinic celsian and some amorphous phase(s). The fibers in this surface ply of the CMC had broken into small pieces. The fiber-matrix interface strength was characterized through fiber push-in technique. Values of debond stress, alpha(sub d), and frictional sliding stress, tau(sub f), for the as-fabricated CMC were 0.31+/-0.14 GPa and 10.4+/-3.1 MPa, respectively. These values compared with 0.53+/-0.47 GPa and 8.33+/-1.72 MPa for the fibers in the interior of the 1200 C annealed sample, indicating hardly any change in fiber-matrix interface strength. The effects of thermal aging on microstructure were investigated using scanning electron microscopy. Only the surface ply of the 1200 C annealed specimens had degraded from oxidation whereas the bulk interior part of the CMC was unaffected. A mechanism is proposed explaining the various steps involved during the degradation of the CMC on annealing in air at 1200 C.

  18. The flavoured BFSS model at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Asano, Yuhma; Filev, Veselin G. [School of Theoretical Physics, Dublin Institute for Advanced Studies,10 Burlington Road, Dublin 4 (Ireland); Kováčik, Samuel [School of Theoretical Physics, Dublin Institute for Advanced Studies,10 Burlington Road, Dublin 4 (Ireland); Faculty of Mathematics, Physics and Informatics,Comenius University Bratislava, Mlynská dolina, Bratislava, 842 48 (Slovakia); O’Connor, Denjoe [School of Theoretical Physics, Dublin Institute for Advanced Studies,10 Burlington Road, Dublin 4 (Ireland)

    2017-01-25

    We study the high-temperature series expansion of the Berkooz-Douglas matrix model, which describes the D0/D4-brane system. At high temperature the model is weakly coupled and we develop the series to second order. We check our results against the high-temperature regime of the bosonic model (without fermions) and find excellent agreement. We track the temperature dependence of the bosonic model and find backreaction of the fundamental fields lifts the zero-temperature adjoint mass degeneracy. In the low-temperature phase the system is well described by a gaussian model with three masses m{sub A}{sup t}=1.964±0.003, m{sub A}{sup l}=2.001±0.003 and m{sub f}=1.463±0.001, the adjoint longitudinal and transverse masses and the mass of the fundamental fields respectively.

  19. Dynamic mechanical response and a constitutive model of Fe-based high temperature alloy at high temperatures and strain rates.

    Science.gov (United States)

    Su, Xiang; Wang, Gang; Li, Jianfeng; Rong, Yiming

    2016-01-01

    The effects of strain rate and temperature on the dynamic behavior of Fe-based high temperature alloy was studied. The strain rates were 0.001-12,000 s(-1), at temperatures ranging from room temperature to 800 °C. A phenomenological constitutive model (Power-Law constitutive model) was proposed considering adiabatic temperature rise and accurate material thermal physical properties. During which, the effects of the specific heat capacity on the adiabatic temperature rise was studied. The constitutive model was verified to be accurate by comparison between predicted and experimental results.

  20. The Effect of Morphological Characteristic of Coarse Aggregates Measured with Fractal Dimension on Asphalt Mixture’s High-Temperature Performance

    Directory of Open Access Journals (Sweden)

    Hainian Wang

    2016-01-01

    Full Text Available The morphological properties of coarse aggregates, such as shape, angularity, and surface texture, have a great influence on the mechanical performance of asphalt mixtures. This study aims to investigate the effect of coarse aggregate morphological properties on the high-temperature performance of asphalt mixtures. A modified Los Angeles (LA abrasion test was employed to produce aggregates with various morphological properties by applying abrasion cycles of 0, 200, 400, 600, 800, 1000, and 1200 on crushed angular aggregates. Based on a laboratory-developed Morphology Analysis System for Coarse Aggregates (MASCA, the morphological properties of the coarse aggregate particles were quantified using the index of fractal dimension. The high-temperature performances of the dense-graded asphalt mixture (AC-16, gap-graded stone asphalt mixture (SAC-16, and stone mastic asphalt (SMA-16 mixtures containing aggregates with different fractal dimensions were evaluated through the dynamic stability (DS test and the penetration shear test in laboratory. Good linear correlations between the fractal dimension and high-temperature indexes were obtained for all three types of mixtures. Moreover, the results also indicated that higher coarse aggregate angularity leads to stronger high-temperature shear resistance of asphalt mixtures.

  1. The effects of high temperature and roof modification on physiological responses of swamp buffalo ( Bubalus bubalis) in the tropics

    Science.gov (United States)

    Khongdee, Titaporn; Sripoon, S.; Vajrabukka, C.

    2013-05-01

    The objective of the experiments reported here was to measure the effects of cooling techniques (Modified roof vs Normal roof) on the performance and physiology of 12 young male buffaloes with a similar live weight of 160 kg. The study was conducted at Chainat Agriculture and Technology College, Chainat Province, Thailand. The animals were divided randomly into two groups, each group comprising six buffaloes, and the two groups were studied to evaluate the effects of modified roofing (normal roof fitted with woven polypropylene shade cloth) on the subjects' physiological responses to heat stress under hot humid conditions. The modified roof resulted in lowered heat stress in buffaloes compared to those under a standard roof. The difference was shown by the buffaloes having a significantly lower mean rectal temperature (39.14 ± 0.07 vs 40.00 ± 0.10°C) and plasma cortisol (2.14 ± 0.24 vs 3.38 ± 0.37 ng/ml). The average daily water consumption was significantly lower in the MR group (MR, 29.71 ± 0.86 vs NR, 34.14 ± 1.06 L head -1 day-1), while there was a tendency for the roughage intake to be higher in the MR group compared to that of the NR group (MR, 5.88 ± 0.18 vs NR, 6.44 ± 0.19 kg head-1 -1 day-1; P = 0.0508). It was concluded that roof modification facilitated a reduction in heat load from roof re-radiation, and was an effective means of alleviating thermal stress in young buffaloes.

  2. Application of High Temperature Superconductors to Accelerators

    CERN Document Server

    Ballarino, A

    2000-01-01

    Since the discovery of high temperature superconductivity, a large effort has been made by the scientific community to investigate this field towards a possible application of the new oxide superconductors to different devices like SMES, magnetic bearings, flywheels energy storage, magnetic shielding, transmission cables, fault current limiters, etc. However, all present day large scale applications using superconductivity in accelerator technology are based on conventional materials operating at liquid helium temperatures. Poor mechanical properties, low critical current density and sensitivity to the magnetic field at high temperature are the key parameters whose improvement is essential for a large scale application of high temperature superconductors to such devices. Current leads, used for transferring currents from the power converters, working at room temperature, into the liquid helium environment, where the magnets are operating, represent an immediate application of the emerging technology of high t...

  3. IPN Polysiloxane-Epoxy Resin for High Temperature Coatings: Structure Effects on Layer Performance after 450 °C Treatment

    Directory of Open Access Journals (Sweden)

    Simone Giaveri

    2017-11-01

    Full Text Available Coatings for high temperatures (HT > 400 °C are obtained from interpenetrating polymer network (IPN binders formed by simultaneous polymerization of silicone and epoxide pre-polymers. A ceramic layer; mainly composed of silica and fillers; remains on the metal surface after a thermal treatment at 450 °C. The layer adhesion and the inorganic filler’s distribution have been investigated by, firstly, exchanging the organic substituents (methyl and phenyl of the silicone chains and, secondly, by adding conductive graphene nanoplatelets with the aim to assure a uniform distribution of heat during the thermal treatment. The results are evidence that different substituent ratios affect the polymer initial layout. The adhesion tests of paint formulations are analysed and were related to instrumental analyses performed using glow discharge optical emission spectroscopy (GDOES; thermal analyses (TG/DTA and DSC; electron microscopy with energy dispersive X-ray analysis (SEM-EDX. A greater resistance to powdering using phenyl groups instead of methyl ones; and an improved distribution of fillers due to graphene nanoplatelet addition; is evidenced.

  4. Hydrodynamic Effects on Modeling and Control of a High Temperature Active Magnetic Bearing Pump with a Canned Rotor

    Energy Technology Data Exchange (ETDEWEB)

    Melin, Alexander M [ORNL; Kisner, Roger A [ORNL; Fugate, David L [ORNL; Holcomb, David Eugene [ORNL

    2015-01-01

    Embedding instrumentation and control Embedding instrumentation and control (I\\&C) at the component level in nuclear power plants can improve component performance, lifetime, and resilience by optimizing operation, reducing the constraints on physical design, and providing on-board prognostics and diagnostics. However, the extreme environments that many nuclear power plant components operate in makes embedding instrumentation and control at the component level difficult. Successfully utilizing embedded I\\&C requires developing a deep understanding of the system's dynamics and using that knowledge to overcome material and physical limitations imposed by the environment. In this paper, we will develop a coupled dynamic model of a high temperature (700 $^\\circ$C) canned rotor pump that incorporates rotordynamics, hydrodynamics, and active magnetic bearing dynamics. Then we will compare two control design methods, one that uses a simplified decoupled model of the system and another that utilizes the full coupled system model. It will be seen that utilizing all the available knowledge of the system dynamics in the controller design yield an order of magnitude improvement in the magnitude of the magnetic bearing response to disturbances at the same level of control effort, a large reduction in the settling time of the system, and a smoother control action.

  5. Dynamic Model of High Temperature PEM Fuel Cell Stack Temperature

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2007-01-01

    The present work involves the development of a model for predicting the dynamic temperature of a high temperature PEM (HTPEM) fuel cell stack. The model is developed to test different thermal control strategies before implementing them in the actual system. The test system consists of a prototype...... cathode air cooled 30 cell HTPEM fuel cell stack developed at the Institute of Energy Technology at Aalborg University. This fuel cell stack uses PEMEAS Celtec P-1000 membranes, runs on pure hydrogen in a dead end anode configuration with a purge valve. The cooling of the stack is managed by running...... the stack at a high stoichiometric air flow. This is possible because of the PBI fuel cell membranes used, and the very low pressure drop in the stack. The model consists of a discrete thermal model dividing the stack into three parts: inlet, middle and end and predicting the temperatures in these three...

  6. High-temperature heat-pump fluids

    Science.gov (United States)

    Bertinat, M. P.

    1988-05-01

    Heat pumps could be immensely useful in many industrial processes, but standard working fluids are unsuitable for the high temperatures involved. The ideal high-temperature heat-pump fluid should have a high (but not too high) critical temperature, a moderate critical pressure ( approximately=5.0 MPa) and a low (but not too low) boiling point. There are many organic fluids that do meet the above thermodynamic criteria The author's list of 250 contained dozens of them including many of the common laboratory solvents such as ethanol, ether and especially acetone. Unfortunately most of them are highly flammable. The ideal work fluid for high-temperature heat pumps will probably always remain elusive and water, despite its drawbacks will continue to be the best choice in most applications

  7. The high-flux effect on deuterium retention in TiC and TaC doped tungsten at high temperatures

    Science.gov (United States)

    Zibrov, Mikhail; Bystrov, Kirill; Mayer, Matej; Morgan, Thomas W.; Kurishita, Hiroaki

    2017-10-01

    Samples made of tungsten (W) doped either with titanium carbide (W-1.1TiC) or tantalum carbide (W-3.3TaC) were exposed to a low-energy (40 eV/D), high-flux (1.8-5 × 1023 D/m2s) deuterium (D) plasma at temperatures of about800 K, 1050 K, and 1250 K to a fluence of about1 × 1027 D/m2. The deuterium (D) inventory in the samples was examined by nuclear reaction analysis and thermal desorption spectroscopy. At 800 K the D bulk concentrations and total D inventories in W-1.1TiC and W-3.3TaC were more than one order of magnitude higher compared to that in pure polycrystalline W. At 1050 K and 1250 K the D concentrations in all types of samples were very low (≤10-5 at. fr.); however the D inventories in W-1.1TiC were significantly higher compared to those in W-3.3TaC and pure W. It is suggested that D trapping inside the carbide precipitates and at their boundaries is essential at high temperatures and high incident fluxes, especially in W-1.1TiC.

  8. Thermomechanics of composite structures under high temperatures

    CERN Document Server

    Dimitrienko, Yu I

    2016-01-01

    This pioneering book presents new models for the thermomechanical behavior of composite materials and structures taking into account internal physico-chemical transformations such as thermodecomposition, sublimation and melting at high temperatures (up to 3000 K). It is of great importance for the design of new thermostable materials and for the investigation of reliability and fire safety of composite structures. It also supports the investigation of interaction of composites with laser irradiation and the design of heat-shield systems. Structural methods are presented for calculating the effective mechanical and thermal properties of matrices, fibres and unidirectional, reinforced by dispersed particles and textile composites, in terms of properties of their constituent phases. Useful calculation methods are developed for characteristics such as the rate of thermomechanical erosion of composites under high-speed flow and the heat deformation of composites with account of chemical shrinkage. The author expan...

  9. Effect of thermal exposure, forming, and welding on high-temperature, dispersion-strengthened aluminum alloy: Al-8Fe-1V-2Si

    Science.gov (United States)

    Kennedy, J. R.; Gilman, P. S.; Zedalis, M. S.; Skinner, D. J.; Peltier, J. M.

    1991-01-01

    The feasibility of applying conventional hot forming and welding methods to high temperature aluminum alloy, Al-8Fe-1V-2Si (FVS812), for structural applications and the effect of thermal exposure on mechanical properties were determined. FVS812 (AA8009) sheet exhibited good hot forming and resistance welding characteristics. It was brake formed to 90 deg bends (0.5T bend radius) at temperatures greater than or equal to 390 C (730 F), indicating the feasibility of fabricating basic shapes, such as angles and zees. Hot forming of simple contoured-flanged parts was demonstrated. Resistance spot welds with good static and fatigue strength at room and elevated temperatures were readily produced. Extended vacuum degassing during billet fabrication reduced porosity in fusion and resistance welds. However, electron beam welding was not possible because of extreme degassing during welding, and gas-tungsten-arc welds were not acceptable because of severely degraded mechanical properties. The FVS812 alloy exhibited excellent high temperature strength stability after thermal exposures up to 315 C (600 F) for 1000 h. Extended billet degassing appeared to generally improve tensile ductility, fatigue strength, and notch toughness. But the effects of billet degassing and thermal exposure on properties need to be further clarified. The manufacture of zee-stiffened, riveted, and resistance-spot-welded compression panels was demonstrated.

  10. The high-flux effect on deuterium retention in TiC and TaC doped tungsten at high temperatures

    NARCIS (Netherlands)

    Zibrov, M.; Bystrov, K.; Mayer, M.; Morgan, T. W.; Kurishita, H.

    2017-01-01

    Samples made of tungsten (W) doped either with titanium carbide (W-1.1TiC) or tantalum carbide (W-3.3TaC) were exposed to a low-energy (40 eV/D), high-flux (1.8–5 × 1023 D/m2s) deuterium (D) plasma at temperatures of about800 K, 1050 K, and 1250 K to a fluence of about1 × 1027 D/m2. The deuterium

  11. Sandia_HighTemperatureComponentEvaluation_2015

    Energy Technology Data Exchange (ETDEWEB)

    Cashion, Avery T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    The objective of this project is to perform independent evaluation of high temperature components to determine their suitability for use in high temperature geothermal tools. Development of high temperature components has been increasing rapidly due to demand from the high temperature oil and gas exploration and aerospace industries. Many of these new components are at the late prototype or first production stage of development and could benefit from third party evaluation of functionality and lifetime at elevated temperatures. In addition to independent testing of new components, this project recognizes that there is a paucity of commercial-off-the-shelf COTS components rated for geothermal temperatures. As such, high-temperature circuit designers often must dedicate considerable time and resources to determine if a component exists that they may be able to knead performance out of to meet their requirements. This project aids tool developers by characterization of select COTS component performances beyond published temperature specifications. The process for selecting components includes public announcements of project intent (e.g., FedBizOps), direct discussions with candidate manufacturers,and coordination with other DOE funded programs.

  12. Effects of High-Temperature Treatment on the Reaction Between Sn-3%Ag-0.5%Cu Solder and Sputtered Ni-V Film on Ferrite Substrate

    Science.gov (United States)

    Shen, Xiaohu; Jin, Hao; Dong, Shurong; Wong, Hei; Zhou, Jian; Guo, Zhaodi; Wang, Demiao

    2012-11-01

    We have demonstrated a novel sputtering method for lead-free thin metal films on ferrite substrates for surface-mount inductor applications. In a surface-mounting process, the cladding of enameled wire needs to be burnt off at high temperature, which requires the devices to withstand a high-temperature reliability test at 420°C for 10 s. There are no reports that a sputtered film of thickness less than 6 μm can withstand this test. In this work, we used Ag/Ni-7 wt.%V double metal layers for the metallization. The dissolution of Ni-7 wt.%V in Sn-3%Ag-0.5%Cu lead-free solder at various temperatures was studied in detail. Scanning electron microscopy with energy-dispersive x-ray spectroscopy was used to investigate the interfacial reaction between the sputtered films and the solder. The intermetallic compounds are mainly (Cu,Ni)6Sn5 at 250°C; however, (Ni,Cu)3Sn4 becomes the predominant composition at 420°C. In addition, although outdiffusion of V atoms from the Ni-V layer was observed, its effect on the intermetallic compound (IMC) was insignificant. We further confirmed that the proposed metallization is able to pass the aforementioned high-temperature reliability test.

  13. Protective Effect of Nitric Oxide on High Temperature Induced Oxidative Stress in Wheat (Triticum aestivum Callus Culture

    Directory of Open Access Journals (Sweden)

    Hossam Saad EL-BELTAGI

    2016-06-01

    Full Text Available High temperature (HT stress is a major environmental factor that limits plant growth, metabolism and productivity worldwide. Plant growth and development involve numerous biochemical reactions that are sensitive to temperature. Plants’ responses to HT vary with the degree and duration of HT and the plants’ adaptability. The protective effect of exogenous nitric oxide in alleviating high temperature induced damages of wheat (Triticum aestivum callus tissues was investigated. Heat treatment (35 and 40 °C alone or in combination with 0.5 mM sodium nitroprusside (SNP; nitric oxide donor was applied for 72 h to callus tissues cultured on MS medium. Heat stress significantly increased lipid peroxidation, hydrogen peroxide and superoxide anion radical levels, whereas ascorbate and total glutathione contents markedly decreased. In addition, heat stress increased the activities of antioxidant defense enzymes: superoxide distumase, ascorbate peroxidase and glutathione reductase. In contrast, the addition of SNP in the culture media prevented the callus from the heat-induced oxidative damage as indicated by the decrease of MDA, H2O2 and O2.− contents, and increased the activities of antioxidant enzymes and non-enzymatic antioxidant constituents. These results provided support for the hypothesis that the exogenous applications of NO confer tolerance to high temperature stress by reducing the oxidative damage in plants.

  14. Elastic properties and stress-temperature phase diagrams of high-temperature phases with low-temperature lattice instabilities

    Science.gov (United States)

    Thomas, John C.; Van der Ven, Anton

    2014-12-01

    The crystal structures of many technologically important high-temperature phases are predicted to have lattice instabilities at low temperature, making their thermodynamic and mechanical properties inaccessible to standard first principles approaches that rely on the (quasi) harmonic approximation. Here, we use the recently developed anharmonic potential cluster expansion within Monte Carlo simulations to predict the effect of temperature and anisotropic stress on the elastic properties of ZrH2, a material that undergoes diffusionless transitions among cubic, tetragonal, and orthorhombic phases. Our analysis shows that the mechanical properties of high-temperature phases with low-temperature vibrational instabilities are very sensitive to temperature and stress state. These findings have important implications for materials characterization and multi-scale simulations and suggest opportunities for enhanced strain engineering of high-temperature phases exhibiting soft-mode instabilities.

  15. Furan Occurrence in Starchy Food Model Systems Processed at High Temperatures: Effect of Ascorbic Acid and Heating Conditions

    DEFF Research Database (Denmark)

    Mariotti, María; Granby, Kit; Fromberg, Arvid

    2012-01-01

    Furan, a potential carcinogen, has been detected in highly consumed starchy foods, such as bread and snacks; however, research on furan generation in these food matrixes has not been undertaken, thus far. The present study explored the effect of ascorbic acid addition and cooking methods (frying...... and baking) over furan occurrence and its relation with the non-enzymatic browning in a wheat flour starchy food model system. Results showed that furan generation significantly increased in the presence of ascorbic acid after 7 min of heating (p

  16. Aeronautical applications of high-temperature superconductors

    Science.gov (United States)

    Turney, George E.; Luidens, Roger W.; Uherka, Kenneth; Hull, John

    1989-01-01

    The successful development of high-temperature superconductors (HTS) could have a major impact on future aeronautical propulsion and aeronautical flight vehicle systems. A preliminary examination of the potential application of HTS for aeronautics indicates that significant benefits may be realized through the development and implementation of these newly discovered materials. Applications of high-temperature superconductors (currently substantiated at 95 k) were envisioned for several classes of aeronautical systems, including subsonic and supersonic transports, hypersonic aircraft, V/STOL aircraft, rotorcraft, and solar, microwave and laser powered aircraft. Introduced and described are the particular applications and potential benefits of high-temperature superconductors as related to aeronautics and/or aeronautical systems.

  17. Symposium on high temperature and materials chemistry

    Energy Technology Data Exchange (ETDEWEB)

    1989-10-01

    This volume contains the written proceedings of the Symposium on High Temperature and Materials Chemistry held in Berkeley, California on October 24--25, 1989. The Symposium was sponsored by the Materials and Chemical Sciences Division of Lawrence Berkeley Laboratory and by the College of Chemistry of the University of California at Berkeley to discuss directions, trends, and accomplishments in the field of high temperature and materials chemistry. Its purpose was to provide a snapshot of high temperature and materials chemistry and, in so doing, to define status and directions.

  18. Silicon Carbide Nanotube Oxidation at High Temperatures

    Science.gov (United States)

    Ahlborg, Nadia; Zhu, Dongming

    2012-01-01

    Silicon Carbide Nanotubes (SiCNTs) have high mechanical strength and also have many potential functional applications. In this study, SiCNTs were investigated for use in strengthening high temperature silicate and oxide materials for high performance ceramic nanocomposites and environmental barrier coating bond coats. The high · temperature oxidation behavior of the nanotubes was of particular interest. The SiCNTs were synthesized by a direct reactive conversion process of multiwall carbon nanotubes and silicon at high temperature. Thermogravimetric analysis (TGA) was used to study the oxidation kinetics of SiCNTs at temperatures ranging from 800degC to1300degC. The specific oxidation mechanisms were also investigated.

  19. High temperature spectral gamma well logging

    Energy Technology Data Exchange (ETDEWEB)

    Normann, R.A.; Henfling, J.A.

    1997-01-01

    A high temperature spectral gamma tool has been designed and built for use in small-diameter geothermal exploration wells. Several engineering judgments are discussed regarding operating parameters, well model selection, and signal processing. An actual well log at elevated temperatures is given with spectral gamma reading showing repeatability.

  20. Effect of high-temperature/current stress on the forward tunneling current of InGaN/GaN high-power blue-light-emitting diodes

    Science.gov (United States)

    Liu, Sheng; Zheng, Chenju; Lv, Jiajiang; Liu, Mengling; Zhou, Shengjun

    2017-08-01

    Through the analysis of the temperature-dependent current-voltage (I-V) characteristics of the fabricated InGaN/GaN high-power blue-light-emitting diodes (LEDs), the low-bias region was confirmed to be dominated by tunneling current, while the medium-bias region was dominated by diffusion-recombination current. Electrons and heavy holes appeared to play similar roles in the tunneling current of the fabricated LEDs, with no apparent dominant tunneling entity determined by characteristic energy as previous works suggested. After 1000 h of high-temperature/current stress, the medium-bias regions of the I-V curves of LEDs remained almost unchanged, while the current in the low-bias region was greatly enhanced by the stress, which confirmed the different carrier transport mechanism behaviors in the low- and medium-bias regions. Further comparison between the I-V characteristics of the unstressed and stressed LEDs suggested that the change in I-V curve was associated with the increase in defect density and the apparent doping concentration in the InGaN/GaN multiple-quantum-well (MQW) active region.

  1. Dynamics of ordering in highly degenerate models with anisotropic grain-boundary potential: Effects of temperature and vortex formation

    DEFF Research Database (Denmark)

    Jeppesen, Claus; Flyvbjerg, Henrik; Mouritsen, Ole G.

    1989-01-01

    universality class, and that all models with nonconserved order parameter, independent of ordering degeneracy and softness and origin of domain boundaries, obey the classical growth law at finite temperatures. In quenches to the Potts-ordered phase vortices and antivortices occur and annihilate mutually......-boundary network. The time evolution of this quantity is shown to obey the growth law, ΔE(t)∼t-n, over an extended time range at late times. It is found that the zero-temperature dynamics is characterized by a special exponent value which for the Q=48 model is n≃0.25 in accordance with earlier work. However......, for quenches to finite temperatures in the Potts-ordered phase there is a distinct crossover to the classical Lifshitz-Allen-Cahn exponent value, n=1 / 2, for both values of Q. This supports the conjecture that the zero-temperature dynamics for models with soft domain boundaries belong to a special...

  2. Dynamic high-temperature Kolsky tension bar techniques

    OpenAIRE

    Song Bo; Nelson Kevin; Lipinski Ronald; Bignell John; Ulrich G.B.; George E.P.

    2015-01-01

    Kolsky tension bar techniques were modified for dynamic high-temperature tensile characterization of thin-sheet alloys. An induction coil heater was used to heat the specimen while a cooling system was applied to keep the bars at room temperature during heating. A preload system was developed to generate a small pretension load in the bar system during heating in order to compensate for the effect of thermal expansion generated in the high-temperature tensile specimen. A laser system was appl...

  3. Variable effects of temperature on insect herbivory

    Directory of Open Access Journals (Sweden)

    Nathan P. Lemoine

    2014-05-01

    Full Text Available Rising temperatures can influence the top-down control of plant biomass by increasing herbivore metabolic demands. Unfortunately, we know relatively little about the effects of temperature on herbivory rates for most insect herbivores in a given community. Evolutionary history, adaptation to local environments, and dietary factors may lead to variable thermal response curves across different species. Here we characterized the effect of temperature on herbivory rates for 21 herbivore-plant pairs, encompassing 14 herbivore and 12 plant species. We show that overall consumption rates increase with temperature between 20 and 30 °C but do not increase further with increasing temperature. However, there is substantial variation in thermal responses among individual herbivore-plant pairs at the highest temperatures. Over one third of the herbivore-plant pairs showed declining consumption rates at high temperatures, while an approximately equal number showed increasing consumption rates. Such variation existed even within herbivore species, as some species exhibited idiosyncratic thermal response curves on different host plants. Thus, rising temperatures, particularly with respect to climate change, may have highly variable effects on plant-herbivore interactions and, ultimately, top-down control of plant biomass.

  4. High-Temperature Hot Air/Silane Coupling Modification of Wood Fiber and Its Effect on Properties of Wood Fiber/HDPE Composites

    Science.gov (United States)

    Chen, Feng; Han, Guangping; Li, Qingde; Gao, Xun; Cheng, Wanli

    2017-01-01

    The surfaces of poplar wood fibers were modified using high-temperature hot air (HTHA) treatment and silane coupling agent. The single factor test was then used to investigate the performances (e.g., the change of functional groups, polarity, cellulose crystallinity, and thermal stability) of modified poplar wood fibers (mPWF) through Fourier transform infrared spectrometry, X-ray diffraction and thermo-gravimetric analysis for the subsequent preparation of wood-plastic composites (WPCs). The effect of HTHA treatment conditions—such as temperature, inlet air velocity, and feed rate—on the performances of WPCs was also investigated by scanning electron microscopy and dynamic mechanical analysis. The main findings indicated that HTHA treatment could promote the hydration of mPWF and improve the mechanical properties of WPCs. Treatment temperature strongly affected the mechanical properties and moisture adsorption characteristics of the prepared composites. With the increase of treated temperature and feed rate, the number of hydroxyl groups, holocellulose content, and the pH of mPWF decreased. The degree of crystallinity and thermal stability and the storage modulus of the prepared composites of mPWF increased. However, dimensional stability and water absorption of WPCs significantly reduced. The best mechanical properties enhancement was observed with treatment temperature at 220 °C. This study demonstrated the feasibility for the application of an HTHA treatment in the WPC production industry. PMID:28772646

  5. High-Temperature Hot Air/Silane Coupling Modification of Wood Fiber and Its Effect on Properties of Wood Fiber/HDPE Composites

    Directory of Open Access Journals (Sweden)

    Feng Chen

    2017-03-01

    Full Text Available The surfaces of poplar wood fibers were modified using high-temperature hot air (HTHA treatment and silane coupling agent. The single factor test was then used to investigate the performances (e.g., the change of functional groups, polarity, cellulose crystallinity, and thermal stability of modified poplar wood fibers (mPWF through Fourier transform infrared spectrometry, X-ray diffraction and thermo-gravimetric analysis for the subsequent preparation of wood-plastic composites (WPCs. The effect of HTHA treatment conditions—such as temperature, inlet air velocity, and feed rate—on the performances of WPCs was also investigated by scanning electron microscopy and dynamic mechanical analysis. The main findings indicated that HTHA treatment could promote the hydration of mPWF and improve the mechanical properties of WPCs. Treatment temperature strongly affected the mechanical properties and moisture adsorption characteristics of the prepared composites. With the increase of treated temperature and feed rate, the number of hydroxyl groups, holocellulose content, and the pH of mPWF decreased. The degree of crystallinity and thermal stability and the storage modulus of the prepared composites of mPWF increased. However, dimensional stability and water absorption of WPCs significantly reduced. The best mechanical properties enhancement was observed with treatment temperature at 220 °C. This study demonstrated the feasibility for the application of an HTHA treatment in the WPC production industry.

  6. High temperatures influence sexual development differentially in ...

    Indian Academy of Sciences (India)

    Samadhan Krushna Phuge

    2017-06-20

    Jun 20, 2017 ... temperatures on gonadal development, sex ratio and metamorphosis was studied in the Indian skipper frog, Euphlyctis ..... Table 1. Effect of rearing water temperature on gonadal differentiation and sex ratio of Euphlyctis cyanophlyctis .... tures (28, 30 and 32°C) induced female to male sex reversal.

  7. Novel High Temperature Strain Gauge Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced high-temperature sensor technology and bonding methods are of great interests in designing and developing advanced future aircraft. Current state-of-the-art...

  8. High Temperature Fiberoptic Thermal Imaging System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed Phase 1 program will fabricate and demonstrate a small diameter single fiber endoscope that can perform high temperature thermal imaging in a jet engine...

  9. High Temperature Capacitors for Venus Exploration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High temperature power electronics have become a vital aspect of future designs for power converters in spacecraft, battle zone electric power, satellite power...

  10. Ion Based High-Temperature Pressure Sensor

    National Research Council Canada - National Science Library

    Zdenek, Jeffrey S; Anthenien, Ralph A

    2004-01-01

    .... The environment encountered in such engines necessitates high temperature and durable (vibration resistant) devices. Traditional pressure sensors can be used, however thermal insulating materials must be used to protect the diaphragm...

  11. NASA High Operating Temperature Technology Program Overview

    Science.gov (United States)

    Nguyen, Q. V.; Hunter, G. W.

    2017-11-01

    NASA’s Planetary Science Division has begun the High Operating Temperature Technology (HOTTech) program to address Venus surface technology challenges by investing in new technology development. This presentation reviews this HOTTech program.

  12. Panel report on high temperature ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Nolet, T C [ed.

    1979-01-01

    Fundamental research is reported concerning high temperature ceramics for application in turbines, engines, batteries, gasifiers, MHD, fuel cells, heat exchangers, and hot wall combustors. Ceramics microstructure and behavior are included. (FS)

  13. Effect of high magnetic field on carbide precipitation in W{sub 6}Mo{sub 5}Cr{sub 4}V{sub 3} high-speed steel during low-temperature tempering

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yan [Northeastern Univ., Shenyang (China). Research Inst.; Li, Hui-Hui; Zhang, Zhi-Wei; Tong, Lu; Zhao, Xiang [Northeastern Univ., Shenyang (China). Key Lab. for Anisotropy and Texture of Materials (Ministry of Education)

    2016-04-15

    The effect of a high magnetic field on carbide precipitation in W{sub 6}Mo{sub 5}Cr{sub 4}V{sub 3} high-speed steel during low-temperature tempering was investigated. The applied high magnetic field promoted the precipitation of M{sub 6}C-type carbides at boundaries and in the grain interior, but maximum spheroidization and refinement occurred for those carbides precipitated at boundaries. Compared with M{sub 6}C-type carbides, the effect of high magnetic field on the precipitation behavior of MC-type carbides is much weaker. The high magnetic field hindered M{sub 2}C-type carbide precipitation by affecting the Gibbs free energy and increased the microhardness of W{sub 6}Mo{sub 5}Cr{sub 4}V{sub 3} high-speed steel at low tempering temperature.

  14. Effect of dietary manganese on antioxidant status and expressions of heat shock proteins and factors in tissues of laying broiler breeders under normal and high environmental temperatures.

    Science.gov (United States)

    Zhu, Yong-Wen; Lu, Lin; Li, Wen-Xiang; Zhang, Li-Yang; Ji, Cheng; Lin, Xi; Liu, Hsiao-Ching; Odle, Jack; Luo, Xu-Gang

    2016-12-01

    To investigate the effect of Mn on antioxidant status and on the expressions of heat shock proteins/factors in tissues of laying broiler breeders subjected to heat challenge, we used a completely randomised design (n 6) with a factorial arrangement of 2 environmental temperatures (normal, 21±1°C, and high, 32±1°C)×3 dietary Mn treatments (a Mn-unsupplemented basal diet (CON), or a basal diet supplemented with 120 mg Mn/kg diet, either as inorganic Mn sulphate (iMn) or as organic Mn proteinate (oMn)). There were no interactions (P>0·10) between environmental temperature and dietary Mn in any of the measured indices. High temperature decreased (PBroiler breeders fed either iMn or oMn had higher tissue Mn content (PBroiler breeders fed oMn had higher (Pbroiler breeders. Furthermore, dietary supplementation with Mn in either source may enhance the heart's antioxidant ability and inhibit the expression of HSP70 in breast muscle. Finally, the organic Mn appears to be more available than inorganic Mn for bone in laying broiler breeders regardless of environmental temperatures.

  15. Mechanical Proprieties of Steel at High Temperatures

    Directory of Open Access Journals (Sweden)

    Ana-Diana Ancaş

    2005-01-01

    Full Text Available The experimental test results obtained in the study of steel mechanical proprieties variation in case of high temperatures (fire are presented. The proprieties are referring to: Young’s modulus, E, the elastic limit, σe, and the characteristic diagram of the material (the rotation stress-strain. Theoretical laws that the model the steel behaviour at high temperature have been elaborated based on the most significant studies presented in the literature.

  16. High temperature superconductors and other superfluids

    CERN Document Server

    Alexandrov, A S

    2017-01-01

    Written by eminent researchers in the field, this text describes the theory of superconductivity and superfluidity starting from liquid helium and a charged Bose-gas. It also discusses the modern bipolaron theory of strongly coupled superconductors, which explains the basic physical properties of high-temperature superconductors. This book will be of interest to fourth year graduate and postgraduate students, specialist libraries, information centres and chemists working in high-temperature superconductivity.

  17. Effects of radiant temperature on thermal comfort

    Energy Technology Data Exchange (ETDEWEB)

    Atmaca, Ibrahim; Kaynakli, Omer; Yigit, Abdulvahap [Uludag University, Bursa (Turkey). Faculty of Engineering and Architecture, Department of Mechanical Engineering

    2007-09-15

    The aim of this paper is to investigate the local differences between body segments caused by high radiant temperature, and to analyze the interior surface temperatures for different wall and ceiling constructions with their effect on thermal comfort. For the segment-wise thermal interactions between human body and its surrounding, simulations have been conducted by appropriately modifying Gagge 2-node model to multi-segment case to demonstrate the local differences. Simulation results are found to be in good agreement with experimental and simulation results reported in the literature. To calculate the interior surface temperatures of the wall and ceiling, the sol-air temperature approach is used for convenience. It is shown in the paper that the body segments close the relatively hot surfaces are more affected than others and interior surface temperatures of un-insulated walls and ceilings exposed to a strong solar radiation reach high levels, all of which cause thermal discomfort for the occupants in buildings. (author)

  18. Laser Plasma Coupling for High Temperature Hohlraums

    Energy Technology Data Exchange (ETDEWEB)

    Kruer, W.

    1999-11-04

    Simple scaling models indicate that quite high radiation temperatures can be achieved in hohlraums driven with the National Ignition Facility. A scaling estimate for the radiation temperature versus pulse duration for different size NIF hohlraums is shown in Figure 1. Note that a radiation temperature of about 650 ev is projected for a so-called scale 1 hohlraum (length 2.6mm, diameter 1.6mm). With such high temperature hohlraums, for example, opacity experiments could be carried out using more relevant high Z materials rather than low Z surrogates. These projections of high temperature hohlraums are uncertain, since the scaling model does not allow for the very strongly-driven laser plasma coupling physics. Lasnex calculations have been carried out to estimate the plasma and irradiation conditions in a scale 1 hohlraum driven by NIF. Linear instability gains as high as exp(100) have been found for stimulated Brillouin scattering, and other laser-driven instabilities are also far above their thresholds. More understanding of the very strongly-driven coupling physics is clearly needed in order to more realistically assess and improve the prospects for high temperature hohlraums. Not surprisingly, this regime has been avoided for inertial fusion applications and so is relatively unexplored.

  19. Electrons and Phonons in High Temperature Superconductors

    Directory of Open Access Journals (Sweden)

    Anu Singh

    2013-01-01

    Full Text Available The defect-induced anharmonic phonon-electron problem in high-temperature superconductors has been investigated with the help of double time thermodynamic electron and phonon Green’s function theory using a comprehensive Hamiltonian which includes the contribution due to unperturbed electrons and phonons, anharmonic phonons, impurities, and interactions of electrons and phonons. This formulation enables one to resolve the problem of electronic heat transport and equilibrium phenomenon in high-temperature superconductors in an amicable way. The problem of electronic heat capacity and electron-phonon problem has been taken up with special reference to the anharmonicity, defect concentration electron-phonon coupling, and temperature dependence.

  20. Effect of torrefaction on the properties of rice straw high temperature pyrolysis char: Pore structure, aromaticity and gasification activity.

    Science.gov (United States)

    Chen, Handing; Chen, Xueli; Qin, Yueqiang; Wei, Juntao; Liu, Haifeng

    2017-03-01

    The influence of torrefaction on the physicochemical characteristics of char during raw and water washed rice straw pyrolysis at 800-1200°C is investigated. Pore structure, aromaticity and gasification activity of pyrolysis chars are compared between raw and torrefied samples. For raw straw, BET specific surface area decreases with the increased torrefaction temperature at the same pyrolysis temperature and it approximately increases linearly with weight loss during pyrolysis. The different pore structure evolutions relate to the different volatile matters and pore structures between raw and torrefied straw. Torrefaction at higher temperature would bring about a lower graphitization degree of char during pyrolysis of raw straw. Pore structure and carbon crystalline structure evolutions of raw and torrefied water washed straw are different from these of raw straw during pyrolysis. For both raw and water washed straw, CO 2 gasification activities of pyrolysis chars are different between raw and torrefied samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Effect of nano packaging on preservation quality of Nanjing 9108 rice variety at high temperature and humidity.

    Science.gov (United States)

    Wang, Fan; Hu, Qiuhui; Mugambi Mariga, Alfred; Cao, Chongjiang; Yang, Wenjian

    2018-01-15

    A nano packaging material containing nano Ag, nano TiO2, nano attapulgite and SiO2 was prepared, and its impact on quality of Nanjing 9108 rice at 37°C and 85% relative humidity was studied. Effects of the packaging on ambient gases and chromatic aberration of rice were determined. Moreover, oxidation level, molds growth and flavor of rice were also analyzed. Results showed that nano packaging material had antimicrobial effects and maintained low O2 and high CO2 content in the packages. The packages thereby inhibited the growth of molds and the production of fatty acids, restrained the increase of lipase activity, and reduced the oxidation of fats and proteins. As a result, the production of yellow and white-belly rice were inhibited. Furthermore, the color and flavor of rice were maintained. Therefore, the nano-packing material could be applied for preservation of rice to improve preservation quality. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Robust high temperature oxygen sensor electrodes

    DEFF Research Database (Denmark)

    Lund, Anders

    reaction kinetics. At oxygen partial pressures below 10-6 bar at 700 C, the mass transport processes dominated the response time. The response time increased with decreasing oxygen partial pressure and inlet gas flow rate. A series of porous platinum electrodes were impregnated with the ionically...... conducting gadolinium-doped cerium oxide (CGO). The addition of CGO was found to decrease the polarisation resistance of the oxygen reaction by up to an order of magnitude compared with a single phase platinum electrode by increasing the effective triple phase boundary (TPB) length. It did not have any......Platinum is the most widely used material in high temperature oxygen sensor electrodes. However, platinum is expensive and the platinum electrode may, under certain conditions, suffer from poisoning, which is detrimental for an oxygen sensor. The objective of this thesis is to evaluate electrode...

  3. Melt processed high-temperature superconductors

    CERN Document Server

    1993-01-01

    The achievement of large critical currents is critical to the applications of high-temperature superconductors. Recent developments have shown that melt processing is suitable for producing high J c oxide superconductors. Using magnetic forces between such high J c oxide superconductors and magnets, a person could be levitated.This book has grown largely out of research works on melt processing of high-temperature superconductors conducted at ISTEC Superconductivity Research Laboratory. The chapters build on melt processing, microstructural characterization, fundamentals of flux pinning, criti

  4. Neutron experiments on high-temperature superconductors

    Science.gov (United States)

    Mook, H. A., Jr.

    1989-12-01

    This report details the trip to the ILL to perform neutron scattering research on high-temperature superconductivity. The trip was very successful because of the excellent users' facilities available at the ILL. The data we accumulated were of high quality and will make an impact on our understanding of high-temperature superconductivity. However, we cannot continue to run a research program in this field with the limited beam time available at the ILL. To make substantial progress in this field, we must restart the High Flux Isotope Reactor.

  5. High Temperature, Wireless Seismometer Sensor for Venus

    Science.gov (United States)

    Ponchak, George E.; Scardelletti, Maximilian C.; Taylor, Brandt; Beard, Steve; Meredith, Roger D.; Beheim, Glenn M.; Hunter Gary W.; Kiefer, Walter S.

    2012-01-01

    Space agency mission plans state the need to measure the seismic activity on Venus. Because of the high temperature on Venus (462? C average surface temperature) and the difficulty in placing and wiring multiple sensors using robots, a high temperature, wireless sensor using a wide bandgap semiconductor is an attractive option. This paper presents the description and proof of concept measurements of a high temperature, wireless seismometer sensor for Venus. A variation in inductance of a coil caused by the movement of an aluminum probe held in the coil and attached to a balanced leaf-spring seismometer causes a variation of 700 Hz in the transmitted signal from the oscillator/sensor system at 426? C. This result indicates that the concept may be used on Venus.

  6. High-temperature granulites and supercontinents

    Directory of Open Access Journals (Sweden)

    J.L.R. Touret

    2016-01-01

    Full Text Available The formation of continents involves a combination of magmatic and metamorphic processes. These processes become indistinguishable at the crust-mantle interface, where the pressure-temperature (P-T conditions of (ultra high-temperature granulites and magmatic rocks are similar. Continents grow laterally, by magmatic activity above oceanic subduction zones (high-pressure metamorphic setting, and vertically by accumulation of mantle-derived magmas at the base of the crust (high-temperature metamorphic setting. Both events are separated from each other in time; the vertical accretion postdating lateral growth by several tens of millions of years. Fluid inclusion data indicate that during the high-temperature metamorphic episode the granulite lower crust is invaded by large amounts of low H2O-activity fluids including high-density CO2 and concentrated saline solutions (brines. These fluids are expelled from the lower crust to higher crustal levels at the end of the high-grade metamorphic event. The final amalgamation of supercontinents corresponds to episodes of ultra-high temperature metamorphism involving large-scale accumulation of these low-water activity fluids in the lower crust. This accumulation causes tectonic instability, which together with the heat input from the sub-continental lithospheric mantle, leads to the disruption of supercontinents. Thus, the fragmentation of a supercontinent is already programmed at the time of its amalgamation.

  7. Effects of Yttrium and Iron co-doping on the high temperature thermoelectric properties of Ca3Co4O9+δ

    DEFF Research Database (Denmark)

    Wu, NingYu; Van Nong, Ngo; Pryds, Nini

    2015-01-01

    A series of Y and Fe co-doped Ca3−xYxCo4−yFeyO9+δ (0 ⩽ x ⩽ 0.3, 0 ⩽ y ⩽ 0.1) samples synthesized by auto-combustion reaction and followed by a spark plasma sintering (SPS) processing with the effects of Fe and Y doping on the high temperature (RT to 800 °C) thermoelectric properties were systemat......A series of Y and Fe co-doped Ca3−xYxCo4−yFeyO9+δ (0 ⩽ x ⩽ 0.3, 0 ⩽ y ⩽ 0.1) samples synthesized by auto-combustion reaction and followed by a spark plasma sintering (SPS) processing with the effects of Fe and Y doping on the high temperature (RT to 800 °C) thermoelectric properties were...... systematically investigated. For the Fe-doped system (x = 0, y ⩽ 0.1), the electrical resistivity (ρ) decreased over the whole measured temperature range, while the Seebeck coefficient (S) remained almost the same. For the co-doped system, at any fixed Fe doping content, both ρ and S tended to increase...... with increasing Y dopants, however, the effect is more substantial on ρ than on S, particularly in the low temperature regime. In contrast to ρ and S, the in-plane thermal conductivity (κ) is only slightly influenced by Y and Fe substitutions. Among all the investigated samples, the co-doped sample with x = 0...

  8. Ceramic membranes for high temperature hydrogen separation

    Energy Technology Data Exchange (ETDEWEB)

    Fain, D.E.; Roettger, G.E. [Oak Ridge K-25 Site, TN (United States)

    1996-08-01

    Ceramic gas separation membranes can provide very high separation factors if the pore size is sufficiently small to separate gas molecules by molecular sieving and if oversized pores are adequately limited. Ceramic membranes typically have some pores that are substantially larger than the mean pore size and that should be regarded as defects. To assess the effects of such defects on the performance of ceramic membranes, a simple mathematical model has been developed to describe flow through a gas separation membrane that has a primary mode of flow through very small pores but that has a secondary mode of flow through undesirably large pores. This model permits separation factors to be calculated for a specified gas pair as a function of the molecular weights and molecular diameters of the gases, the membrane pore diameter, and the diameter and number of defects. This model will be described, and key results from the model will be presented. The separation factors of the authors membranes continue to be determined using a permeance test system that measures flows of pure gases through a membrane at temperatures up to 275{degrees}C. A primary goal of this project for FY 1996 is to develop a mixed gas separation system for measuring the separation efficiency of membranes at higher temperatures. Performance criteria have been established for the planned mixed gas separation system and design of the system has been completed. The test system is designed to measure the separation efficiency of membranes at temperatures up to 600{degrees}C and pressures up to 100 psi by separating the constituents of a gas mixture containing hydrogen. The system will accommodate the authors typical experimental membrane that is tubular and has a diameter of about 9 mm and a length of about 23 cm. The design of the new test system and its expected performance will be discussed.

  9. High temperature and performance in a flight task simulator.

    Science.gov (United States)

    1972-05-01

    The effects of high cockpit temperature on physiological responses and performance were determined on pilots in a general aviation simulator. The pilots (all instrument rated) 'flew' an instrument flight while exposed to each of three cockpit tempera...

  10. HIGH TEMPERATURE HIGH PRESSURE THERMODYNAMIC MEASUREMENTS FOR COAL MODEL COMPOUNDS

    Energy Technology Data Exchange (ETDEWEB)

    Vinayak N. Kabadi

    1999-02-20

    It is well known that the fluid phase equilibria can be represented by a number of {gamma}-models , but unfortunately most of them do not function well under high temperature. In this calculation, we mainly investigate the performance of UNIQUAC and NRTL models under high temperature, using temperature dependent parameters rather than using the original formulas. the other feature of this calculation is that we try to relate the excess Gibbs energy G{sup E}and enthalpy of mixing H{sup E}simultaneously. In other words, we will use the high temperature and pressure G{sup E} and H{sup E}data to regress the temperature dependant parameters to find out which model and what kind of temperature dependant parameters should be used.

  11. Experimental Characterization of the Poisoning Effects of Methanol-Based Reformate Impurities on a PBI-Based High Temperature PEM Fuel Cell

    Directory of Open Access Journals (Sweden)

    Samuel Simon Araya

    2012-10-01

    Full Text Available In this work the effects of reformate gas impurities on a H3PO4-doped polybenzimidazole (PBI membrane-based high temperature proton exchange membrane fuel cell (HT-PEMFC are studied. A unit cell assembly with a BASF Celtec®-P2100 high temperature membrane electrode assembly (MEA of 45 cm2 active surface area is investigated by means of impedance spectroscopy. The concentrations in the anode feed gas of all impurities, unconverted methanol-water vapor mixture, CO and CO2 were varied along with current density according to a multilevel factorial design of experiments. Results show that all the impurities degrade the performance, with CO being the most degrading agent and CO2 the least. The factorial analysis shows that there is interdependence among the effects of the different factors considered. This interdependence suggests, for example, that tolerances to concentrations of CO above 2% may be compromised by the presence in the anode feed of CO2. Methanol has a poisoning effect on the fuel cell at all the tested feed ratios, and the performance drop is found to be proportional to the amount of methanol in feed gas. The effects are more pronounced when other impurities are also present in the feed gas, especially at higher methanol concentrations.

  12. Modeling the Effects of Cu Content and Deformation Variables on the High-Temperature Flow Behavior of Dilute Al-Fe-Si Alloys Using an Artificial Neural Network.

    Science.gov (United States)

    Shakiba, Mohammad; Parson, Nick; Chen, X-Grant

    2016-06-30

    The hot deformation behavior of Al-0.12Fe-0.1Si alloys with varied amounts of Cu (0.002-0.31 wt %) was investigated by uniaxial compression tests conducted at different temperatures (400 °C-550 °C) and strain rates (0.01-10 s-1). The results demonstrated that flow stress decreased with increasing deformation temperature and decreasing strain rate, while flow stress increased with increasing Cu content for all deformation conditions studied due to the solute drag effect. Based on the experimental data, an artificial neural network (ANN) model was developed to study the relationship between chemical composition, deformation variables and high-temperature flow behavior. A three-layer feed-forward back-propagation artificial neural network with 20 neurons in a hidden layer was established in this study. The input parameters were Cu content, temperature, strain rate and strain, while the flow stress was the output. The performance of the proposed model was evaluated using the K-fold cross-validation method. The results showed excellent generalization capability of the developed model. Sensitivity analysis indicated that the strain rate is the most important parameter, while the Cu content exhibited a modest but significant influence on the flow stress.

  13. Low Temperature Heating and High Temperature Cooling in Buildings

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk

    , a single-family house designed for plus-energy targets and equipped with a radiant water-based floor heating and cooling system was studied by means of full-scale measurements, dynamic building simulations and thermodynamic evaluation tools. Thermal indoor environment and energy performance of the house......A heating and cooling system could be divided into three parts: terminal units (emission system), distribution system, and heating and cooling plant (generation system). The choice of terminal unit directly affects the energy performance, and the indoor environment in that space. Therefore......, a holistic system evaluation is necessary to ensure an optimal indoor environment for the occupants and to achieve energy efficiency simultaneously. Low temperature heating and high temperature cooling systems are one of the possible approaches to heat or cool indoor spaces in buildings. In this thesis...

  14. Analysis of the high-temperature particulate collection problem

    Energy Technology Data Exchange (ETDEWEB)

    Razgaitis, R.

    1977-10-01

    Particulate agglomeration and separation at high temperatures and pressures are examined, with particular emphasis on the unique features of the direct-cycle application of fluidized-bed combustion. The basic long-range mechanisms of aerosol separation are examined, and the effects of high temperature and high pressure on usable collection techniques are assessed. Primary emphasis is placed on those avenues that are not currently attracting widespread research. The high-temperature, particulate-collection problem is surveyed, together with the peculiar requirements associated with operation of turbines with particulate-bearing gas streams. 238 references.

  15. Effects of dietary supplemental sodium bicarbonate on some egg characteristics and blood parameters in Japanese Quail reared under high enviromental temperature

    OpenAIRE

    Okan, Ferda

    1998-01-01

    The aim of this study was to determine the effects of dietary supplemental sodium bicarbonate on egg production, egg weight, shell quality, feed conversion efficiency, blood pH, plasma Na+ values and blood gas in Japanese quail Layers reared under high environmental temperature. In this study, 9 weeks old 60 female Japanese quail Layers were used and divided equally into two groups. The control group was fed with basal diet where the second group was fed with a diet containing 0.2 % NaHCO3. ...

  16. Core Physics of Pebble Bed High Temperature Nuclear Reactors

    NARCIS (Netherlands)

    Auwerda, G.J.

    2014-01-01

    To more accurately predict the temperature distribution inside the reactor core of pebble bed type high temperature reactors, in this thesis we investigated the stochastic properties of randomly stacked beds and the effects of the non-homogeneity of these beds on the neutronics and

  17. Influence of temperature on denitrification of an industrial high ...

    African Journals Online (AJOL)

    The temperature effect on denitrification rate of a two-sludge system has been studied. An industrial high-strength wastewater and an industrial by-product containing mainly methanol, as external carbon source, were used in this study. The maximum denitrification rate (MDR) was determined at six different temperatures: 6, ...

  18. Effect of high-temperature on the swellable organically-modified silica (SOMS) and its application to gas-phase hydrodechlorination of trichloroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Sohn, Hyuntae; Celik, Gokhan; Gunduz, Seval; Majumdar, Sreshtha Sinha; Dean, Stacey L.; Edmiston, Paul L.; Ozkan, Umit S.

    2017-07-01

    Pd catalysts supported on swellable organically-modified silica (SOMS) and high-temperature-treated swellable organically-modified silica (H-SOMS) were characterized and tested for gas-phase hydrodechlorination (HDC) of trichloroethylene (TCE) conditions. The high-temperature treatment on SOMS resulted in an increase in surface area and pore diameter as well as significant improvement of Pd dispersion on H-SOMS with smaller Pd particle sizes compared to the Pd/SOMS catalyst. Although the high-temperature treatment led to some alteration of the SOMS polysiloxane network, the hydrophobicity and organic vapor adsorption characteristics of SOMS were preserved. The reduction and oxidation characteristics of Pd on SOMS and HSOMS were investigated in situ using XANES technique. It was found that the Pd sites in the pores of SOMS was accessible to small molecules such as H2, facilitating the reduction of PdOx, whereas oxidation of metallic Pd was limited even at higher temperatures when O2 was used. This effect was only observed over Pd/SOMS catalyst. For Pd/H-SOMS, because the pores were more widely open than Pd/SOMS, both reduction and oxidation of Pd were observed. Finally, the catalytic activity of Pd/H-SOMS for gas-phase HDC of TCE was significantly better than Pd/SOMS. When water was added to the reactant stream (TCE + H2O), both Pd/SOMS and Pd/H-SOMS maintained its catalytic performances due to hydrophobic property of the supports.

  19. Effective Energy Transfer via Plasmon-Activated High-Energy Water Promotes Its Fundamental Activities of Solubility, Ionic Conductivity, and Extraction at Room Temperature

    Science.gov (United States)

    Yang, Chih-Ping; Chen, Hsiao-Chien; Wang, Ching-Chiung; Tsai, Po-Wei; Ho, Chia-Wen; Liu, Yu-Chuan

    2015-12-01

    Water is a ubiquitous solvent in biological, physical, and chemical processes. Unique properties of water result from water’s tetrahedral hydrogen-bonded (HB) network (THBN). The original THBN is destroyed when water is confined in a nanosized environment or localized at interfaces, resulting in corresponding changes in HB-dependent properties. In this work, we present an innovative idea to validate the reserve energy of high-energy water and applications of high-energy water to promote water’s fundamental activities of solubility, ionic conductivity, and extraction at room temperature. High-energy water with reduced HBs was created by utilizing hot electrons with energies from the decay of surface plasmon excited at gold (Au) nanoparticles (NPs). Compared to conventional deionized (DI) water, solubilities of alkali metal-chloride salts in high-energy water were significantly increased, especially for salts that release heat when dissolved. The ionic conductivity of NaCl in high-energy water was also markedly higher, especially when the electrolyte’s concentration was extremely low. In addition, antioxidative components, such as polyphenols and 2,3,5,4’-tetrahydroxystilbene-2-O-beta-d-glucoside (THSG) from teas, and Polygonum multiflorum (PM), could more effectively be extracted using high-energy water. These results demonstrate that high-energy water has emerged as a promising innovative solvent for promoting water’s fundamental activities via effective energy transfer.

  20. Cadmium and high temperature effects on brain and behaviour of Lymantria dispar L. caterpillars originating from polluted and less-polluted forests.

    Science.gov (United States)

    Perić-Mataruga, Vesna; Petković, Branka; Ilijin, Larisa; Mrdaković, Marija; Dronjak Čučaković, Slađana; Todorović, Dajana; Vlahović, Milena

    2017-10-01

    Insects brain as a part of nervous system is the first-line of fast stress response that integrate stress signals to regulate all aspects of insect physiology and behaviour. The cadmium (Cd) bioaccumulation factor (BF), activity of the neurotoxicity biomarker acetylcholinesterase (AChE), dopamine content, expression and amount of Hsp70 in the brain and locomotor activity were evaluated in the 4th instar of Lymantria dispar L. caterpillars fed a Cd supplemented diet and reared in an optimal temperature regime (23 °C) and/or exposed to high temperature (28 °C). The insects originated from two forests, one close to "Nikola Tesla" thermoelectric power plant, Obrenovac (polluted population), and the other Kosmaj mountain (less-polluted population, far from any industrial region). The Cd BF was higher in the less-polluted than in the polluted population especially at the high ambient temperature. AChE activity and dopamine content were changed in the brains of L. dispar from both populations in the same manner. Hsp70 concentration in caterpillar brains showed opposite trends, a decrease in the less-polluted and an increase in the polluted population. Locomotor activity was modified in both Lymantria dispar populations, but the pattern of changes depended on the stressors and their combined effect. ACh activity and dopamine content are sensitive parameters to Cd exposure, regardless of pollutant experience, and might be promising biomarkers in monitoring forest ecosystems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. The Effect of Lipolytic Enzymes of Bacillus spp. on Quality of Ultra-High-Temperature-Treated Milk

    Directory of Open Access Journals (Sweden)

    B. Janštová

    2006-01-01

    Full Text Available Lipolysis was monitored based on determining the concentration of free fatty acids in milk, on the model case of UHT milk contamination with spores of 15 B. licheniformis, B. subtilis and B. cereus strains isolated from farm environment and raw milk. Lipolysis was not recorded at storage temperature of 4 °C, whereas significant changes in levels of free fatty acids were shown at storage temperature of 24 °C. After 3 weeks of storage the initial content of 41.97 mmol·kg-1 of fat rose to as much as 1,617.22 mmol·kg-1 of fat. The extent of the change depended mainly on the Bacillus spp. species and the storage period and, to a certain degree, also on the initial number of microorganisms. Significant lipolytic activity was detected in association with B. licheniformis and B. cereus species. It was found that spores of resistant B. licheniformis strains may survive 100 °C/10 min and 135 °C/5 s heating and show lipolytic activity.

  2. Effect of low and high storage temperatures on head space gas concentrations and physical properties of wood pellets

    Energy Technology Data Exchange (ETDEWEB)

    Jaya Shankar Tumuluru; Shahab Sokhansanj; C. Jim Lim; Tony Bi; Xingya Kuang; Staffan Melin

    2013-11-01

    Headspace gas concentrations and wood pellet properties were studied in sealed glass canisters at 5–40 degrees C storage temperatures. CO2 and CO concentrations at 5, 10, 20 and 40 degrees C at the end of 23–28 days of storage were 1600 and 200, 4700 and 1200, and 31 200 and 15 800 parts per million by volume (ppmv) respectively. Corresponding O2 concentration was about 19•49, 19•20, 18•0 and 2•07% respectively. Non-linear regression equations adequately described the gas concentrations in the storage container as a function of time. Safe level estimation functions developed were linear for O2 and logarithmic for CO and CO2 concentrations. Measured pellet properties moisture, length, diameter, unit, bulk and tapped density, durability, calorific value, ash content and per cent fines were in the range of 4•6–5•02%, 14–15 mm, 6•4–6•5 mm, 1125–1175 kg m-3, 750–770 kg m-3, 825–840 kg m-3, 73–74%, 18•32–18•78 MJ kg-1, 0•65–0•74% and 0•13–0•15%. Durability values of pellets decreased by 13% at 40 degrees C storage temperature and other properties changed marginally.

  3. Effect of low-temperature long-time and high-temperature short-time blanching and frying treatments on the French fry quality of six Irish potato cultivars.

    Science.gov (United States)

    Ngobese, Nomali Ziphorah; Workneh, Tilahun Seyoum; Siwela, Muthulisi

    2017-02-01

    Processing conditions are an important determinant of French fry quality. However, the effect of low-temperature long-time (LTLT) and high-temperature short-time (HTST) blanching and frying treatments has not been investigated in many cultivars. The current study investigates the effect of the sequential application of these treatments on French fries processed from six Irish potato cultivars (Fianna, Innovator, Mondial, Navigator, Panamera and Savanna). Blanching was effected at 75 °C for 10 min or 85 °C for 5 min and frying was effected at 160 °C for 2 min or 180 °C for 1 min. These treatments resulted in significant differences in the quality of the fries across the cultivars. The blanching treatments had a greater impact on the French fry quality than the frying treatments. LTLT blanching resulted in lower oil (12-13% fresh mass basis [fmb]), and higher protein (3.5-4.3% fmb) and mineral content in the French fries processed from Innovator, compared to HTST blanching. This was accompanied by a crispier crust, which required a greater puncture force (1.2-2.1 N) for penetration. Blanching with the LTLT treatment before HTST frying resulted in French fries that were the most acceptable to consumers and these were from Fianna, Innovator and Mondial. The current study demonstrates that the effect of French fry processing conditions is cultivar-dependent.

  4. High temperature thrust chamber for spacecraft

    Science.gov (United States)

    Chazen, Melvin L. (Inventor); Mueller, Thomas J. (Inventor); Kruse, William D. (Inventor)

    1998-01-01

    A high temperature thrust chamber for spacecraft (20) is provided herein. The high temperature thrust chamber comprises a hollow body member (12) having an outer surface and an internal surface (16) defining the high temperature chamber (10). The body member (12) is made substantially of rhenium. An alloy (18) consisting of iridium and at least alloying metal selected of the group consisting of rhodium, platinum and palladium is deposited on at least a portion of the internal surface (16) of the body member (12). The iridium and the alloying metal are electrodeposited onto the body member (12). A HIP cycle is performed upon the body member (12) to cause the coating of iridium and the alloying metal to form the alloy (18) which protects the body member (12) from oxidation.

  5. Stability projections for high temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Laquer, H.L.; Edeskuty, F.J.; Hassenzahl, W.V.; Wipf, S.L.

    1989-03-01

    The stability of the new high temperature superconducting oxides has been analyzed, using the methodology developed over the last 25 years for conventional Type II superconductors. The results are presented in graphical form for the temperature range from 4 to 100 K. For a 90 K superconductor the first flux jump field peaks above 7 T at 60 K, ( and for a 120 k superconductor it peaks above 12 T at 75 K). The maximum adiabatically stable thickness increases dramatically. The linear dimension of the minimum propagating zone increases by a factor of 3 to 5, and the quench propagation velocity drops by 4 orders of magnitude. The high temperature superconducting materials will, therefore, have much higher stability than conventional Type II superconductors; their high flux jump fields will make ultra-fine multifilamentary conductors unnecessary and improve the outlook for tape conductors; the energy to create a propagating zone is increased; however, methods of coil protection will have to be modified.

  6. X-ray response of CdZnTe detectors grown by the vertical Bridgman technique: Energy, temperature and high flux effects

    Science.gov (United States)

    Abbene, L.; Gerardi, G.; Turturici, A. A.; Raso, G.; Benassi, G.; Bettelli, M.; Zambelli, N.; Zappettini, A.; Principato, F.

    2016-11-01

    Nowadays, CdZnTe (CZT) is one of the key materials for the development of room temperature X-ray and gamma ray detectors and great efforts have been made on both the device and the crystal growth technologies. In this work, we present the results of spectroscopic investigations on new boron oxide encapsulated vertical Bridgman (B-VB) grown CZT detectors, recently developed at IMEM-CNR Parma, Italy. Several detectors, with the same electrode layout (gold electroless contacts) and different thicknesses (1 and 2.5 mm), were realized: the cathode is a planar electrode covering the detector surface (4.1×4.1 mm2), while the anode is a central electrode (2×2 mm2) surrounded by a guard-ring electrode. The detectors are characterized by electron mobility-lifetime product (μeτe) values ranging between 0.6 and 1·10-3 cm2/V and by low leakage currents at room temperature and at high bias voltages (38 nA/cm2 at 10000 V/cm). The spectroscopic response of the detectors to monochromatic X-ray and gamma ray sources (109Cd, 241Am and 57Co), at different temperatures and fluxes (up to 1 Mcps), was measured taking into account the mitigation of the effects of incomplete charge collection, pile-up and high flux radiation induced polarization phenomena. A custom-designed digital readout electronics, developed at DiFC of University of Palermo (Italy), able to perform a fine pulse shape and height analysis even at high fluxes, was used. At low rates (200 cps) and at room temperature (T=25 °C), the detectors exhibit an energy resolution FWHM around 4% at 59.5 keV, for comparison an energy resolution of 3% was measured with Al/CdTe/Pt detectors by using the same electronics (A250F/NF charge sensitive preamplifier, Amptek, USA; nominal ENC of 100 electrons RMS). At high rates (750 kcps), energy resolution values of 7% and 9% were measured, with throughputs of 2% and 60% respectively. No radiation polarization phenomena were observed at room temperature up to 1 Mcps (241Am source, 60 ke

  7. High temperature superconductivity the road to higher critical temperature

    CERN Document Server

    Uchida, Shin-ichi

    2015-01-01

    This book presents an overview of material-specific factors that influence Tc and give rise to diverse Tc values for copper oxides and iron-based high- Tc superconductors on the basis of more than 25 years of experimental data, to most of which the author has made important contributions. The book then explains why both compounds are distinct from others with similar crystal structure and whether or not one can enhance Tc, which in turn gives a hint on the unresolved pairing mechanism. This is an unprecedented new approach to the problem of high-temperature superconductivity and thus will be inspiring to both specialists and non-specialists interested in this field.   Readers will receive in-depth information on the past, present, and future of high-temperature superconductors, along with special, updated information on what the real highest Tc values are and particularly on the possibility of enhancing Tc for each member material, which is important for application. At this time, the highest Tc has not been...

  8. Effect of high temperature on cell structure and gluten protein accumulation in the endosperm of the developing wheat (Triticum aestivum L.) grain

    Science.gov (United States)

    High temperature during grain fill is one of the more significant environmental factors that alters wheat yield and flour quality. To identify endosperm responses to high temperature, cell structure and gluten protein composition were investigated in developing wheat (Triticum aestivum L. cv. Butte ...

  9. The effect of high temperature on cell structure and gluten protein accumulation in the endosperm of the developing wheat (Triticum aestivum L.) grain

    Science.gov (United States)

    High temperature during grain fill is one of the more significant environmental factors that alters wheat yield and flour quality. To identify endosperm responses to high temperature, cell structure and gluten protein composition were investigated in developing wheat (Triticum aestivum L. cv. Butte ...

  10. High pressure study of high-temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Souliou, Sofia-Michaela

    2014-09-29

    The current thesis studies experimentally the effect of high external pressure on high-T{sub c} superconductors. The structure and lattice dynamics of several members of the high-T{sub c} cuprate and Fe-based superconductors families were investigated by means of Raman spectroscopy and X-ray diffraction under well-controlled, hydrostatic high pressure and low temperature conditions. The lattice dynamics of the high-T{sub c} superconductor YBa{sub 2}Cu{sub 3}O{sub 6+x} have been investigated systematically by Raman spectroscopy as a function of doping (x = 0.95, 0.75, 0.60, 0.55, and 0.45) and external pressure. Under ambient pressure conditions, in addition to the Raman modes expected from group theory, we observe new Raman active phonons upon cooling the underdoped samples, at temperatures well above the superconducting transition temperature. The doping dependence and the onset temperatures of the new Raman features suggest that they are associated with the incommensurate charge density wave (CDW) state recently discovered in underdoped cuprates using synchrotron X-ray scattering techniques. Under high pressure conditions (from 2 to 12 GPa), our Raman measurements on highly ordered underdoped YBa{sub 2}Cu{sub 3}O{sub 6.55} samples do not show any of the new Raman phonons seen at ambient pressure. High pressure and low temperature Raman measurements have been performed on the underdoped superconductor YBa{sub 2}Cu{sub 4}O{sub 8}. A clear renormalization of some of the Raman phonons is seen below T{sub c} as a result of the changes in the phonon self-energy upon the opening of the superconducting gap, with the most prominent one being that of the B{sub 1g}-like buckling phonon mode. The amplitude of this renormalization strongly increases with pressure, resembling the effect of hole doping in YBa{sub 2}Cu{sub 3}O{sub 6+x}. At ∝ 10 GPa, the system undergoes a reversible pressure-induced structural phase transition to a non-centrosymmmetric structure (space group

  11. Effect of Chromium on Corrosion Behavior of P110 Steels in CO2-H2S Environment with High Pressure and High Temperature

    Science.gov (United States)

    Sun, Jianbo; Sun, Chong; Lin, Xueqiang; Cheng, Xiangkun; Liu, Huifeng

    2016-01-01

    The novel Cr-containing low alloy steels have exhibited good corrosion resistance in CO2 environment, mainly owing to the formation of Cr-enriched corrosion film. In order to evaluate whether it is applicable to the CO2 and H2S coexistence conditions, the corrosion behavior of low-chromium steels in CO2-H2S environment with high pressure and high temperature was investigated using weight loss measurement and surface characterization. The results showed that P110 steel suffered localized corrosion and both 3Cr-P110 and 5Cr-P110 steels exhibited general corrosion. However, the corrosion rate of 5Cr-P110 was the highest among them. The corrosion process of the steels was simultaneously governed by CO2 and H2S. The outer scales on the three steels mainly consisted of FeS1−x crystals, whereas the inner scales on Cr-containing steels comprised of amorphous FeS1−x, Cr(OH)3 and FeCO3, in contrast with the amorphous FeS1−x and FeCO3 mixture film of P110 steel. The more chromium the steel contains, the more chromium compounds the corrosion products contain. The addition of chromium in steels increases the uniformity of the Cr-enriched corrosion scales, eliminates the localized corrosion, but cannot decrease the general corrosion rates. The formation of FeS1−x may interfere with Cr-enriched corrosion scales and lowering the corrosion performance of 3Cr-P110 and 5Cr-P110 steels. PMID:28773328

  12. Effect of Chromium on Corrosion Behavior of P110 Steels in CO2-H2S Environment with High Pressure and High Temperature

    Directory of Open Access Journals (Sweden)

    Jianbo Sun

    2016-03-01

    Full Text Available The novel Cr-containing low alloy steels have exhibited good corrosion resistance in CO2 environment, mainly owing to the formation of Cr-enriched corrosion film. In order to evaluate whether it is applicable to the CO2 and H2S coexistence conditions, the corrosion behavior of low-chromium steels in CO2-H2S environment with high pressure and high temperature was investigated using weight loss measurement and surface characterization. The results showed that P110 steel suffered localized corrosion and both 3Cr-P110 and 5Cr-P110 steels exhibited general corrosion. However, the corrosion rate of 5Cr-P110 was the highest among them. The corrosion process of the steels was simultaneously governed by CO2 and H2S. The outer scales on the three steels mainly consisted of FeS1−x crystals, whereas the inner scales on Cr-containing steels comprised of amorphous FeS1−x, Cr(OH3 and FeCO3, in contrast with the amorphous FeS1−x and FeCO3 mixture film of P110 steel. The more chromium the steel contains, the more chromium compounds the corrosion products contain. The addition of chromium in steels increases the uniformity of the Cr-enriched corrosion scales, eliminates the localized corrosion, but cannot decrease the general corrosion rates. The formation of FeS1−x may interfere with Cr-enriched corrosion scales and lowering the corrosion performance of 3Cr-P110 and 5Cr-P110 steels.

  13. Effects of high and low temperatures on thermal tolerance in Folsomia candida (Collembola)

    DEFF Research Database (Denmark)

    Jensen, Dorthe; Holmstrup, Martin; Bayley, Mark

    2008-01-01

    to fluctuating temperatures. Possible mechanisms behind the heat hardening may be induction of protective stress proteins. The present study also elucidated if molecular responses such as changing activity of protein kinase and gene transcription of stress proteins were involved in the increased heat shock......% survival), - 6.4 or - 7.4 °C (100% mortality) compared with the control. In contrast, fluctuation between 20 and 30.1 °C (± 0.1°C) induced a significantly increased tolerance to a 34.6 °C heat shock with survival increasing from about 10% in the controls to a maximum of 80% in the animals exposed...

  14. Effect of Fe doping on low temperature deNOx activity of high-performance vanadia-anatase nanoparticles

    DEFF Research Database (Denmark)

    Schill, Leonhard; Putluru, Siva Sankar Reddy; Jensen, Anker Degn

    2014-01-01

    VFe/TiO2 catalysts have been prepared using a sol-gel based method. Fe was introduced using 3 different methods. The resulting substances were characterized with N2-physisorption, NH3-TPD, H2-TPR, XPS and XRD. Extrudates of the VFe/TiO2 powders were prepared using sepiolite (20 wt.%) as binder....... The activities of the composite materials in the selective catalytic reduction (SCR) of NO with NH3 were measured at temperatures of up to 200 °C and in the presence of 20 vol. % H2O. Presence of Fe can increase the surface area, enhance the redox properties, increase the number of surface acid sites, increase...... the share of surface adsorbed oxygen and does not induce the formation of crystalline V2O5. However, the measurements performed here show that Fe doping does not cause activity enhancement of the V/TiO2....

  15. Effects of Temperature on Hybrid Lens Performance

    Science.gov (United States)

    Askins, Steve; Victoria, Marta; Herrero, Rebeca; Domínguez, César; Antón, Ignacio; Sala, Gabriel

    2011-12-01

    In hybrid Silicone-on-glass Fresnel lenses, an optical silicone is molded onto a glass substrate and forms the Fresnel structure. These lenses offer a cost effective solution as a primary optical element in point-focus concentrator photovoltaic modules, as well as performance advantages. However, these lenses have a high performance variation with temperature due both to the change in index of refraction of silicone as well as to deformations in the facets caused by coefficient of thermal expansion (CTE) mismatch. In this study we perform measurements of the light flux at the focal plane of a family of SOG lenses, varying temperature and lens-to-receiver distances. The effect of varying silicone cure temperature and the depth of the silicone between the lens and the glass substrate on temperature dependence was investigated. A preliminary computer model of this behavior is presented.

  16. Temperature measurements of high power LEDs

    Science.gov (United States)

    Badalan (Draghici), Niculina; Svasta, Paul; Drumea, Andrei

    2016-12-01

    Measurement of a LED junction temperature is very important in designing a LED lighting system. Depending on the junction temperature we will be able to determine the type of cooling system and the size of the lighting system. There are several indirect methods for junction temperature measurement. The method used in this paper is based on the thermal resistance model. The aim of this study is to identify the best device that would allow measuring the solder point temperature and the temperature on the lens of power LEDs. For this purpose four devices for measuring temperature on a high-power LED are presented and compared according to the acquired measurements: an infrared thermal camera from FLIR Systems, a multimeter with K type thermocouple (Velleman DVM4200), an infrared-spot based noncontact thermometer (Raynger ST) and a measurement system based on a digital temperature sensor (DS1821 type) connected to a PC. The measurements were conducted on an 18W COB (chip-on-board) LED. The measurement points are the supply terminals and the lens of the LED.

  17. Fiber Bragg Grating Filter High Temperature Sensors

    Science.gov (United States)

    Lyons, Donald R.; Brass, Eric D.; Pencil, Eric (Technical Monitor)

    2001-01-01

    We present a scaled-down method for determining high temperatures using fiber-based Bragg gratings. Bragg gratings are distributed along the length of the optical fiber, and have high reflectivities whenever the optical wavelength is twice the grating spacing. These spatially distinct Bragg regions (located in the core of a fiber) are sensitive to local temperature changes. Since these fibers are silica-based they are easily affected by localized changes in temperature, which results in changes to both the grating spacing and the wavelength reflectivity. We exploit the shift in wavelength reflectivity to measure the change in the local temperature. Note that the Bragg region (sensing area) is some distance away from where the temperature is being measured. This is done so that we can measure temperatures that are much higher than the damage threshold of the fiber. We do this by affixing the fiber with the Bragg sensor to a material with a well-known coefficient of thermal expansion, and model the heat gradient from the region of interest to the actual sensor. The research described in this paper will culminate in a working device as well as be the second portion of a publication pending submission to Optics Letters.

  18. Materials for high-temperature fuel cells

    CERN Document Server

    Jiang, San Ping; Lu, Max

    2013-01-01

    There are a large number of books available on fuel cells; however, the majority are on specific types of fuel cells such as solid oxide fuel cells, proton exchange membrane fuel cells, or on specific technical aspects of fuel cells, e.g., the system or stack engineering. Thus, there is a need for a book focused on materials requirements in fuel cells. Key Materials in High-Temperature Fuel Cells is a concise source of the most important and key materials and catalysts in high-temperature fuel cells with emphasis on the most important solid oxide fuel cells. A related book will cover key mater

  19. High temperature and pressure electrochemical test station

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Allebrod, Frank; Mogensen, Mogens Bjerg

    2013-01-01

    An electrochemical test station capable of operating at pressures up to 100 bars and temperatures up to 400 ◦C has been established. It enables control of the partial pressures and mass flow of O2, N2, H2, CO2, and H2O in a single or dual environment arrangement, measurements with highly corrosive......, to the electrochemical characterization of high temperature and pressure alkaline electrolysis cells and the use of pseudo-reference electrodes for the separation of each electrode contribution. A future perspective of various electrochemical processes and devices that can be developed with the use of the established...

  20. High temperature reactors for cogeneration applications

    Energy Technology Data Exchange (ETDEWEB)

    Verfondern, Karl [Forschungszentrum Juelich (Germany). IEK-6; Allelein, Hans-Josef [Forschungszentrum Juelich (Germany). IEK-6; RWTH Aachen (Germany). Lehrstuhl fuer Reaktorsicherheit und -technik (LRST)

    2016-05-15

    There is a large potential for nuclear energy also in the non-electric heat market. Many industrial sectors have a high demand for process heat and steam at various levels of temperature and pressure to be provided for desalination of seawater, district heating, or chemical processes. The future generation of nuclear plants will be capable to enter the wide field of cogeneration of heat and power (CHP), to reduce waste heat and to increase efficiency. This requires an adjustment to multiple needs of the customers in terms of size and application. All Generation-IV concepts proposed are designed for coolant outlet temperatures above 500 C, which allow applications in the low and medium temperature range. A VHTR would even be able to cover the whole temperature range up to approx. 1 000 C.

  1. On-wafer high temperature characterization system

    Science.gov (United States)

    Teodorescu, L.; ǎghici, F., Dr; Rusu, I.; Brezeanu, G.

    2016-12-01

    In this work a on-wafer high temperature characterization system for wide bandgap semiconductor devices and circuits has been designed, implemented and tested. The proposed system can perform the wafer temperature adjustment in a large domain, from the room temperature up to 3000C with a resolution better than +/-0.50C. In order to obtain both low-noise measurements and low EMI, the heating element of the wafer chuck is supplied in two ways: one is from a DC linear power supply connected to the mains electricity, another one is from a second DC unit powered by batteries. An original temperature control algorithm, different from classical PID, is used to modify the power applied to the chuck.

  2. High Temperature Mechanisms for Venus Exploration

    Science.gov (United States)

    Ji, Jerri; Narine, Roop; Kumar, Nishant; Singh, Sase; Gorevan, Steven

    Future Venus missions, including New Frontiers Venus In-Situ Explorer and three Flagship Missions - Venus Geophysical Network, Venus Mobile Explorer and Venus Surface Sample Return all focus on searching for evidence of past climate change both on the surface and in the atmospheric composition as well as in the interior dynamics of the planet. In order to achieve these goals and objectives, many key technologies need to be developed for the Venus extreme environment. These key technologies include sample acquisition systems and other high-temperature mechanisms and mobility systems capable of extended operation when directly exposed to the Venus surface or lower atmosphere environment. Honeybee Robotics has developed two types of high temperature motors, the materials and components in both motors were selected based on the requirement to survive temperatures above a minimum of 460° C, at earth atmosphere. The prototype Switched Reluctance Motor (SRM) has been operated non-continuously for over 20 hours at Venus-like conditions (460° C temperature, mostly CO2 gas environment) and it remains functional. A drilling system, actuated by two SRMs was tested in Venus-like conditions, 460° C temperature and mostly CO2 gas environment, for more than 15 hours. The drill successfully completed three tests by drilling into chalk up to 6 inches deep in each test. A first generation Brushless DC (BLDC) Motor and high temperature resolver were also tested and the feasibility of the designs was demonstrated by the extended operation of both devices under Venus-like condition. Further development of the BLDC motor and resolver continues and these devices will, ultimately, be integrated into the development of a high temperature sample acquisition scoop and high temperature joint (awarded SBIR Phase II in October, 2007). Both the SR and BLDC motors will undergo extensive testing at Venus temperature and pressure (TRL6) and are expected to be mission ready before the next New

  3. Effect of elevated temperature on the properties of silica fume and recycled rubber-filled high strength concretes (RHSC

    Directory of Open Access Journals (Sweden)

    Magda I. Mousa

    2017-04-01

    The results obtained show high resistance to fire with increasing SF content up to 20% replacement of cement. Additional improvement was obtained with using dolomite and 3% of recycled rubber (2 mm, 5 mm.

  4. High-Temperature Shape Memory Polymers

    Science.gov (United States)

    Yoonessi, Mitra; Weiss, Robert A.

    2012-01-01

    physical conformation changes when exposed to an external stimulus, such as a change in temperature. Such materials have a permanent shape, but can be reshaped above a critical temperature and fixed into a temporary shape when cooled under stress to below the critical temperature. When reheated above the critical temperature (Tc, also sometimes called the triggering or switching temperature), the materials revert to the permanent shape. The current innovation involves a chemically treated (sulfonated, carboxylated, phosphonated, or other polar function group), high-temperature, semicrystalline thermoplastic poly(ether ether ketone) (Tg .140 C, Tm = 340 C) mix containing organometallic complexes (Zn++, Li+, or other metal, ammonium, or phosphonium salts), or high-temperature ionic liquids (e.g. hexafluorosilicate salt with 1-propyl-3- methyl imidazolium, Tm = 210 C) to form a network where dipolar or ionic interactions between the polymer and the low-molecular-weight or inorganic compound forms a complex that provides a physical crosslink. Hereafter, these compounds will be referred to as "additives". The polymer is semicrystalline, and the high-melt-point crystals provide a temporary crosslink that acts as a permanent crosslink just so long as the melting temperature is not exceeded. In this example case, the melting point is .340 C, and the shape memory critical temperature is between 150 and 250 C. PEEK is an engineering thermoplastic with a high Young fs modulus, nominally 3.6 GPa. An important aspect of the invention is the control of the PEEK functionalization (in this example, the sulfonation degree), and the thermal properties (i.e. melting point) of the additive, which determines the switching temperature. Because the compound is thermoplastic, it can be formed into the "permanent" shape by conventional plastics processing operations. In addition, the compound may be covalently cross - linked after forming the permanent shape by S-PEEK by applying ionizing

  5. HIGH TEMPERATURE HIGH PRESSURE THERMODYNAMIC MEASUREMENTS FOR COAL MODEL COMPOUNDS

    Energy Technology Data Exchange (ETDEWEB)

    Vinayak N. Kabadi

    2000-05-01

    The Vapor Liquid Equilibrium measurement setup of this work was first established several years ago. It is a flow type high temperature high pressure apparatus which was designed to operate below 500 C temperature and 2000 psia pressure. Compared with the static method, this method has three major advantages: the first is that large quantity of sample can be obtained from the system without disturbing the equilibrium state which was established before; the second is that the residence time of the sample in the equilibrium cell is greatly reduced, thus decomposition or contamination of the sample can be effectively prevented; the third is that the flow system allows the sample to degas as it heats up since any non condensable gas will exit in the vapor stream, accumulate in the vapor condenser, and not be recirculated. The first few runs were made with Quinoline-Tetralin system, the results were fairly in agreement with the literature data . The former graduate student Amad used the same apparatus acquired the Benzene-Ethylbenzene system VLE data. This work used basically the same setup (several modifications had been made) to get the VLE data of Ethylbenzene-Quinoline system.

  6. Effect of Laves Phase on High-Temperature Deformation and Microstructure Evolution in an 18Cr-2Mo-0.5Nb Ferritic Stainless Steel

    Science.gov (United States)

    Ikeda, Ken-ichi; Yamoah, Nana Kwame Gyan; Reynolds, William T.; Hamada, Jun-ichi; Murayama, Mitsuhiro

    2015-08-01

    Niobium-containing ferritic stainless steels are finding new applications in automotive exhaust components because of their oxidation resistance, thermal fatigue resistance, and high-temperature strength. The mechanical behavior of Nb-containing ferritic steels at service temperatures of 973 K (700 °C) and higher results from the convolution of dynamic microstructural changes including precipitation, precipitate coarsening, strain hardening, recovery, and recrystallization. The relative contributions of these competing processes have yet to be clarified. In this study, the high-temperature flow strength of an 18Cr-2Mo-0.5Nb ferritic stainless steel (SUS 444) was correlated with microstructure under different strain and initial precipitate distributions to clarify the relative role of the strengthening and softening processes. High-temperature tensile tests at 1023 K (750 °C) of un-aged (initial microstructure is precipitate-free) and pre-aged (initial microstructure contains precipitates) samples were carried out and transmission electron microscopy was used to assess dislocation distributions and precipitate morphology. The difference in the stress-strain curves between un-aged and pre-aged samples was drastic; the yield strength of the un-aged sample was twice that of the pre-aged sample, and the un-aged sample exhibits a noticeable yield drop. Transmission electron microscopy revealed a Laves phase nucleated and grew during the high-temperature tensile test in the un-aged sample and the majority of the precipitates in the pre-aged sample were the same Laves phase. Furthermore, a strain effect on precipitate growth was recognized in un-aged and pre-aged conditions by comparing grip (no strain) and gage (strained) sections of tensile samples. The dominant strengthening contribution in un-aged samples is initially the precipitate shearing mechanism and it changes to Orowan strengthening beyond the ultimate tensile strength, whereas the dominant contribution in

  7. High Temperature Integrated Thermoelectric Ststem and Materials

    Energy Technology Data Exchange (ETDEWEB)

    Mike S. H. Chu

    2011-06-06

    The final goal of this project is to produce, by the end of Phase II, an all ceramic high temperature thermoelectric module. Such a module design integrates oxide ceramic n-type, oxide ceramic p-type materials as thermoelectric legs and oxide ceramic conductive material as metalizing connection between n-type and p-type legs. The benefits of this all ceramic module are that it can function at higher temperatures (> 700 C), it is mechanically and functionally more reliable and it can be scaled up to production at lower cost. With this all ceramic module, millions of dollars in savings or in new opportunities recovering waste heat from high temperature processes could be made available. A very attractive application will be to convert exhaust heat from a vehicle to reusable electric energy by a thermoelectric generator (TEG). Phase I activities were focused on evaluating potential n-type and p-type oxide compositions as the thermoelectric legs. More than 40 oxide ceramic powder compositions were made and studied in the laboratory. The compositions were divided into 6 groups representing different material systems. Basic ceramic properties and thermoelectric properties of discs sintered from these powders were measured. Powders with different particles sizes were made to evaluate the effects of particle size reduction on thermoelectric properties. Several powders were submitted to a leading thermoelectric company for complete thermoelectric evaluation. Initial evaluation showed that when samples were sintered by conventional method, they had reasonable values of Seebeck coefficient but very low values of electrical conductivity. Therefore, their power factors (PF) and figure of merits (ZT) were too low to be useful for high temperature thermoelectric applications. An unconventional sintering method, Spark Plasma Sintering (SPS) was determined to produce better thermoelectric properties. Particle size reduction of powders also was found to have some positive benefits

  8. Effect of C particle size on the mechanism of self-propagation high-temperature synthesis in the Ni-Ti-C system

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y.F., E-mail: y.yang6@uq.edu.au [University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, QLD 4072 (Australia); Wang, H.Y.; Wang, J.G. [Key Laboratory of Automobile Materials of Ministry of Education, Department of Materials Science and Engineering, Jilin University, Nanling Campus, Changchun 130025 (China); Jiang, Q.C., E-mail: jqc@jlu.edu.cn [Key Laboratory of Automobile Materials of Ministry of Education, Department of Materials Science and Engineering, Jilin University, Nanling Campus, Changchun 130025 (China)

    2011-06-23

    Highlights: > We investigated the effect of C particle size on the self-propagating high temperature reaction mechanism. > Coarse C particle size (>38 {mu}m) resulted in the formation of prior TiC{sub x} layer between Ti and C. > Prior TiC{sub x} layer control the whole reaction of Ni-Ti-C and domain the reaction kinetics. > The selection of C particle size is the most important factor to fabricate TiC/Ni composite using Ti, C and Ni mixtures. - Abstract: Effect of C particle size on the mechanism of self-propagation high-temperature synthesis (SHS) in the Ni-Ti-C system was investigated. Fine C particle resulted in a traditional mechanism of dissolution-precipitation while coarse C particle made the reaction be controlled by a mechanism of the diffusion of C through the TiC{sub x} layer. The whole process can be described: C atoms diffusing through the TiC{sub x} layer dissolved into the Ni-Ti liquid and TiC were formed once the liquid became supersaturated. Simultaneously, the heat generated from the TiC formation made the unstable TiC{sub x} layer break up. However, with the spread of Ti-Ni liquid, a new TiC{sub x} layer was formed again at the interface between spreading liquid and C particle. This process cannot stop until all the C particles are consumed completely.

  9. Effect of Annealing Temperature on the Microstructure, Tensile Properties, and Fracture Behavior of Cold-Rolled High-Mn Light-Weight Steels

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae-Hyun; Cho, Kyung Mox [Pusan National University, Busan (Korea, Republic of); Park, Seong-Jun; Moon, Joonoh; Kang, Jun-Yun; Park, Jun-Young; Lee, Tae-Ho [Korea Institute of Materials Science, Changwon (Korea, Republic of)

    2017-05-15

    The effects of the annealing temperature on the microstructure and tensile properties of cold-rolled light-weight steels are investigated using two Fe-30Mn-xAl-0.9C alloys that contain different Al content. The initial alloy microstructure is composed of a single austenite or a mixture of austenite and ferrite depending on the nominal aluminum content. For the alloy with 9 wt%Al content, the recrystallization and grain growth of austenite occurrs depending on the annealing temperature. However, for the alloy with 11 wt%Al content, the β-Mn phase is observed after annealing for 10 min at 550~800 ℃. The β-Mn transformation kinetics is the fastest at 700 ℃. The formation of the β-Mn phase has a detrimental effect on the ductility, and this leads to significant decreases in the total elongation. The same alloy also forms κ-carbide and DO3 ordering at 550~900 ℃. The investigated alloys exhibit a fully recrystallized microstructure after annealing at 900 ℃ for 10 min, which results in a high total elongation of 25~55%with a high tensile strength of 900~1170 MPa.

  10. RR-MR transition of a Type V shock interaction in inviscid double-wedge flow with high-temperature gas effects

    Science.gov (United States)

    Xiong, W.; Li, J.; Zhu, Y.; Luo, X.

    2017-11-01

    The transition between regular reflection (RR) and Mach reflection (MR) of a Type V shock-shock interaction on a double-wedge geometry with non-equilibrium high-temperature gas effects is investigated theoretically and numerically. A modified shock polar method that involves thermochemical non-equilibrium processes is applied to calculate the theoretical critical angles of transition based on the detachment criterion and the von Neumann criterion. Two-dimensional inviscid numerical simulations are performed correspondingly to reveal the interactive wave patterns, the transition processes, and the critical transition angles. The theoretical and numerical results of the critical transition angles are compared, which shows evident disagreement, indicating that the transition mechanism between RR and MR of a Type V shock interaction is beyond the admissible scope of the classical theory. Numerical results show that the collisions of triple points of the Type V interaction cause the transition instead. Compared with the frozen counterpart, it is found that the high-temperature gas effects lead to a larger critical transition angle and a larger hysteresis interval.

  11. Gravimeter using high-temperature superconductor bearing.

    Energy Technology Data Exchange (ETDEWEB)

    Hull, J. R.

    1998-09-11

    We have developed a sensitive gravimeter concept that uses an extremely low-friction bearing based on a permanent magnet (PM) levitated over a high-temperature superconductor (HTS). A mass is attached to the PM by means of a cantilevered beam, and the combination of PM and HTS forms a bearing platform that has low resistance to rotational motion but high resistance to horizontal, vertical, or tilting motion. The combination acts as a low-loss torsional pendulum that can be operated in any orientation. Gravity acts on the cantilevered beam and attached mass, accelerating them. Variations in gravity can be detected by time-of-flight acceleration, or by a control coil or electrode that would keep the mass stationary. Calculations suggest that the HTS gravimeter would be as sensitive as present-day superconducting gravimeters that need cooling to liquid helium temperatures, but the HTS gravimeter needs cooling only to liquid nitrogen temperatures.

  12. High Accuracy, Miniature Pressure Sensor for Very High Temperatures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — SiWave proposes to develop a compact, low-cost MEMS-based pressure sensor for very high temperatures and low pressures in hypersonic wind tunnels. Most currently...

  13. Research at Very High Pressures and High Temperatures

    Science.gov (United States)

    Bundy, Francis P.

    1977-01-01

    Reviews research and apparatus utilized in the study of the states and characteristics of materials at very high temperatures and pressures. Includes three examples of the research being conducted. (SL)

  14. Lightweight High-Temperature Thermal Insulation

    Science.gov (United States)

    Wagner, W. R.; Fasheh, J. I.

    1985-01-01

    Fine Ni/Cr fibers sintered into corrosion-resistant, fireproof batt. Possible applications include stoves, furnaces, safes, fire clothing, draperies in public buildings, wall firebreaks, airplane walls, and jetengine components. New insulation takes advantage of some of same properties of nickel/chromium alloy useful in heating elements in toasters, namely, corrosion and oxidation resistance even at high temperatures.

  15. High temperatures influence sexual development differentially in ...

    Indian Academy of Sciences (India)

    Although sex determination in amphibians is believed to be a genetic process, environmental factors such as temperatureare known to influence the sex differentiation and development. Extremely low and high temperatures influence gonadaldevelopment and sex ratio in amphibians but the mechanism of action is not ...

  16. High Temperature Corrosion in Biomass Incineration Plants

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Maahn, Ernst emanuel; Gotthjælp, K.

    1997-01-01

    The aim of the project is to study the role of ash deposits in high temperature corrosion of superheater materials in biomass and refuse fire combined heat and power plants. The project has included the two main activities: a) A chemical characterisation of ash deposits collected from a major...

  17. High Temperature Resistant Exhaust Valve Spindle

    DEFF Research Database (Denmark)

    Bihlet, Uffe Ditlev

    of the engine, new high temperature alloys are required for a specific engine component, the exhaust valve spindle. Two alloys are used for an exhaust valve spindle; one for the bottom of the spindle, and one for the spindle seat. Being placed in the exhaust gas stream, combustion products such as V2O5 and Na2...

  18. Helium-cooled high temperature reactors

    Energy Technology Data Exchange (ETDEWEB)

    Trauger, D.B.

    1985-01-01

    Experience with several helium cooled reactors has been favorable, and two commercial plants are now operating. Both of these units are of the High Temperature Graphite Gas Cooled concept, one in the United States and the other in the Federal Republic of Germany. The initial helium charge for a reactor of the 1000 MW(e) size is modest, approx.15,000 kg.

  19. Thermoelastic properties of minerals at high temperature

    Indian Academy of Sciences (India)

    The knowledge of elasticity of the minerals is useful for interpreting the structure and composition of the lower mantle and also in seismic studies. The purpose of the present study is to discuss a simple and straightforward method for evaluating thermoelastic properties of minerals at high temperatures. We have extended ...

  20. High temperature fatigue behaviour of intermetallics

    Indian Academy of Sciences (India)

    There would be considerable benefits in developing new structural materials where high use temperatures and strength coupled with low density are minimum capabilities. Nickel and titanium aluminides exhibit considerable potential for near-term application in various branches of modern industry due to the number of ...

  1. Experimental study to distinguish the effects of methanol slip and water vapour on a high temperature PEM fuel cell at different operating conditions

    DEFF Research Database (Denmark)

    Thomas, Sobi; Vang, Jakob Rabjerg; Araya, Samuel Simon

    2017-01-01

    The objective of this paper is to separate out the effects of methanol and water vapour on a high temperature polymer electrolyte membrane fuel cell under different temperatures (160°C and 180°C) and current densities (0.2Acm-2, 0.4Acm-2 and 0.6Acm-2). The degradation rates at the different current...... the presence of 5% methanol tends to degrade the cell performance. However, the presence of H2O mitigates some of the adverse effects of methanol. The effect of varying fuel compositions was found to be more prominent at lower current densities. The voltage improves significantly when adding water vapour...... to the anode after pure hydrogen operation at 180°C. A decrease in the total resistance corresponding to the voltage improvement is observed from the impedance spectra. There is minimal variation in performance with the introduction of 3% and 5% methanol along with water vapour in the anode feed at all current...

  2. High-pressure-high-temperature treatment of natural diamonds

    CERN Document Server

    Royen, J V

    2002-01-01

    The results are reported of high-pressure-high-temperature (HPHT) treatment experiments on natural diamonds of different origins and with different impurity contents. The diamonds are annealed in a temperature range up to 2000 sup o C at stabilizing pressures up to 7 GPa. The evolution is studied of different defects in the diamond crystal lattice. The influence of substitutional nitrogen atoms, plastic deformation and the combination of these is discussed. Diamonds are characterized at room and liquid nitrogen temperature using UV-visible spectrophotometry, Fourier transform infrared spectrophotometry and photoluminescence spectrometry. The economic implications of diamond HPHT treatments are discussed.

  3. Effect of the dietary probiotic Clostridium butyricum on growth, intestine antioxidant capacity and resistance to high temperature stress in kuruma shrimp Marsupenaeus japonicus.

    Science.gov (United States)

    Duan, Yafei; Zhang, Yue; Dong, Hongbiao; Wang, Yun; Zhang, Jiasong

    2017-05-01

    A 56-day feeding trial followed by an acute high temperature stress test were performed to evaluate the effect of dietary probiotic Clostridium butyricum (CB) on growth performance and intestine antioxidant capacity of kuruma shrimp Marsupenaeus japonicus. Shrimp were randomly allocated in 9 tanks (30 shrimp per tank) and triplicate tanks were fed with diets containing different levels of C. butyricum (1×10(9) cfu/g): 0mgg(-1) feed (Control), 100mgg(-1) feed (CB-100), 200mgg(-1) feed (CB-200) as treatment groups. The results indicated that dietary supplementation of C. butyricum increased the growth performance and decreased the feed conversion rate (FCR) of shrimp in the CB-100 group. HE stain showed that C. butyricum increased the intestine epithelium height of M. japonicus. C. butyricum supplemented in diets decreased·O2(-) generation capacity and malondialdehyde (MDA) content, and increased total antioxidant capacity (T-AOC), catalase (CAT) and peroxidase (POD) activity and the expression level of heat shock protein 70 (hsp70) and metallothionein (mt) gene in intestine of shrimp cultured under normal condition for 56 d, while no significant changes in glutathione peroxidase (GPx) activity and ferritin gene expression level. After shrimp exposed to high temperature stress 48h, the lower level of·O2(-) generation capacity and MDA content, and the higher level survival, activities of T-AOC, CAT, GPx and POD, as well as hsp70, ferritin and mt gene expression level were found in intestine of two C. butyricum groups. These results revealed that C. butyricum could improve the growth performance, increase intestine antioxidant capacity of M. japonicus against high temperature stress, and could be a potential feed additive in shrimp aquaculture. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. High skin temperature and hypohydration impair aerobic performance.

    Science.gov (United States)

    Sawka, Michael N; Cheuvront, Samuel N; Kenefick, Robert W

    2012-03-01

    This paper reviews the roles of hot skin (>35°C) and body water deficits (>2% body mass; hypohydration) in impairing submaximal aerobic performance. Hot skin is associated with high skin blood flow requirements and hypohydration is associated with reduced cardiac filling, both of which act to reduce aerobic reserve. In euhydrated subjects, hot skin alone (with a modest core temperature elevation) impairs submaximal aerobic performance. Conversely, aerobic performance is sustained with core temperatures >40°C if skin temperatures are cool-warm when euhydrated. No study has demonstrated that high core temperature (∼40°C) alone, without coexisting hot skin, will impair aerobic performance. In hypohydrated subjects, aerobic performance begins to be impaired when skin temperatures exceed 27°C, and even warmer skin exacerbates the aerobic performance impairment (-1.5% for each 1°C skin temperature). We conclude that hot skin (high skin blood flow requirements from narrow skin temperature to core temperature gradients), not high core temperature, is the 'primary' factor impairing aerobic exercise performance when euhydrated and that hypohydration exacerbates this effect.

  5. Effect of heating at frying temperature on the quality characteristics of regular and high-oleic acid sunflower oils

    OpenAIRE

    M Abbas Ali; Ali Hassan Ali Najmaldien; Razam Abd Latip; Noor Hidayu Othman; Fadzilah Adibah Abdul Majid; Liza Md Salleh

    2013-01-01

    Background.Understanding of oil deterioration during heating/frying process is important as oils are nor- mally kept hot at commercial food outlets during intermittent frying cycles. An increased level of consumer awareness toward fat composition and its impact on human health could have an effect on selection of fats in the food industry. The rate of quality deterioration during heating depends on fatty acid composition and also the content and composition of minor components. Therefore, the...

  6. Maintenance in Service of High Temperature Parts

    Science.gov (United States)

    1982-01-01

    program activities. io4 6-1 DEFECTS AND THEIR EFFECT ON THE BEHAVIOUR OF GAS TIURBNE DISCS Robert H Jeal Head of Materials Engineering Rolls-Royce Limited...temperature sulphidatien and hot forrosal. m 5.• ACKNOWLEDGEMENT The author wishes to thank N. Swindells of the University of Livernool for his efforts in

  7. Quantitative methods for stochastic high frequency spatio-temporal and non-linear analysis: Assessing health effects of exposure to extreme ambient temperature

    Science.gov (United States)

    Liss, Alexander

    Extreme weather events, such as heat waves and cold spells, cause substantial excess mortality and morbidity in the vulnerable elderly population, and cost billions of dollars. The accurate and reliable assessment of adverse effects of extreme weather events on human health is crucial for environmental scientists, economists, and public health officials to ensure proper protection of vulnerable populations and efficient allocation of scarce resources. However, the methodology for the analysis of large national databases is yet to be developed. The overarching objective of this dissertation is to examine the effect of extreme weather on the elderly population of the Conterminous US (ConUS) with respect to seasonality in temperature in different climatic regions by utilizing heterogeneous high frequency and spatio-temporal resolution data. To achieve these goals the author: 1) incorporated dissimilar stochastic high frequency big data streams and distinct data types into the integrated data base for use in analytical and decision support frameworks; 2) created an automated climate regionalization system based on remote sensing and machine learning to define climate regions for the Conterminous US; 3) systematically surveyed the current state of the art and identified existing gaps in the scientific knowledge; 4) assessed the dose-response relationship of exposure to temperature extremes on human health in relatively homogeneous climate regions using different statistical models, such as parametric and non-parametric, contemporaneous and asynchronous, applied to the same data; 5) assessed seasonal peak timing and synchronization delay of the exposure and the disease within the framework of contemporaneous high frequency harmonic time series analysis and modification of the effect by the regional climate; 6) modeled using hyperbolic functional form non-linear properties of the effect of exposure to extreme temperature on human health. The proposed climate

  8. Effects of Electromagnetic Stirring on the Microstructure and High-Temperature Mechanical Properties of a Hyper-eutectic Al-Si-Cu-Ni Alloy

    Science.gov (United States)

    Jang, Youngsoo; Choi, Byounghee; Kang, Byungkeun; Hong, Chun Pyo

    2015-02-01

    A liquid treatment method by electromagnetic stirring was applied to a hyper-eutectic Al-15wt pctSi-4wt pctCu-3wt pctNi alloy for the piston manufacturing with diecasting process in order to improve high-temperature mechanical properties of the piston heads. The mechanical properties, such as hardness, high-temperature tensile stress, thermal expansion, and high-temperature relative wear resistance, were estimated using the specimens taken from the liquid-treated diecast products, and the results were compared with those of a conventional metal-mold-cast piston.

  9. Sorbents Remove Oxygen At High Temperatures

    Science.gov (United States)

    Sharma, Pramod K.

    1995-01-01

    Cobalt-exchanged, platinized zeolites 13X and L found conveniently reducible in hot gaseous mixture of hydrogen and nitrogen and thereafter useful as sorbents of trace amounts of oxygen at high temperatures. Aided by catalytic action of platinum, sorbents exhibit rapid oxygen-sorption kinetics and, according to thermodynamic properties of O2/CoO system, capable of lowering level of oxygen in otherwise inert gaseous atmosphere to less than 1 part per trillion in temperature range of 400 to 800 degrees C. Inert atmospheres with these oxygen levels required for processing of certain materials in semiconductor industry.

  10. A review of high-temperature adhesives

    Science.gov (United States)

    St.clair, A. K.; St.clair, T. L.

    1981-01-01

    The development of high temperature adhesives and polyphenylquinoxalines (PPQ) is reported. Thermoplastic polyimides and linear PPQ adhesive are shown to have potential for bonding both metals and composite structures. A nadic terminated addition polyimide adhesive, LARC-13, and an acetylene terminated phenylquinoxaline (ATPQ) were developed. Both of the addition type adhesives are shown to be more readily processable than linear materials but less thermooxidatively stable and more brittle. It is found that the addition type adhesives are able to perform, at elevated temperatures up to 595 C where linear systems fail thermoplastically.

  11. Effect of alloy grain size on the high-temperature oxidation behavior of the austenitic steel TP 347

    Directory of Open Access Journals (Sweden)

    Vicente Braz Trindade

    2005-12-01

    Full Text Available Generally, oxide scales formed on high Cr steels are multi-layered and the kinetics are strongly influenced by the alloy grain boundaries. In the present study, the oxidation behaviour of an austenite steel TP347 with different grain sizes was studied to identify the role of grain-boundaries in the oxidation process. Heat treatment in an inert gas atmosphere at 1050 °C was applied to modify the grain size of the steel TP347. The mass gain during subsequent oxidation was measured using a microbalance with a resolution of 10-5 g. The scale morphology was examined using SEM in combination with energy-dispersive X-ray spectroscopy (EDS. Oxidation of TP347 with a grain size of 4 µm at 750 °C in air follows a parabolic rate law. For a larger grain size (65 µm, complex kinetics is observed with a fast initial oxidation followed by several different parabolic oxidation stages. SEM examinations indicated that the scale formed on specimens with smaller grain size was predominantly Cr2O3, with some FeCr2O4 at localized sites. For specimens with larger grain size the main oxide is iron oxide. It can be concluded that protective Cr2O3 formation is promoted by a high density of fast grain-boundary diffusion paths which is the case for fine-grained materials.

  12. High temperature dynamic engine seal technology development

    Science.gov (United States)

    Steinetz, Bruce M.; Dellacorte, Christopher; Machinchick, Michael; Mutharasan, Rajakkannu; Du, Guang-Wu; Ko, Frank; Sirocky, Paul J.; Miller, Jeffrey H.

    1992-01-01

    Combined cycle ramjet/scramjet engines being designed for advanced hypersonic vehicles, including the National Aerospace Plane (NASP), require innovative high temperature dynamic seals to seal the sliding interfaces of the articulated engine panels. New seals are required that will operate hot (1200 to 2000 F), seal pressures ranging from 0 to 100 psi, remain flexible to accommodate significant sidewall distortions, and resist abrasion over the engine's operational life. This report reviews the recent high temperature durability screening assessments of a new braided rope seal concept, braided of emerging high temperature materials, that shows promise of meeting many of the seal demands of hypersonic engines. The paper presents durability data for: (1) the fundamental seal building blocks, a range of candidate ceramic fiber tows; and for (2) braided rope seal subelements scrubbed under engine simulated sliding, temperature, and preload conditions. Seal material/architecture attributes and limitations are identified through the investigations performed. The paper summarizes the current seal technology development status and presents areas in which future work will be performed.

  13. Pre-oxidation and its effect on reducing high-temperature corrosion of superheater tubes during biomass firing

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Kvisgaard, M.; Montgomery, Melanie

    2017-01-01

    Superheater tubes in biomass-fired power plants experience high corrosion rates due to condensation of corrosive alkali chloride-rich deposits. To explore the possibility of reducing the corrosion attack by the formation of an initial protective oxide layer, the corrosion resistance of pre......-oxidised Nimonic 80A remained unaffected suggesting protection of the alloy from the corrosive environment....... with a synthetic deposit of KCl and exposed at 560°C for 1 week to a gas mixture typical of biomass firing. Results show that pre-oxidation could hinder the corrosion attack; however, the relative success was different for the two alloys. While corrosion attack was observed on the pre-oxidised Kanthal APM, the pre...

  14. High temperature sensors for exhaust diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Svenningstorp, Henrik

    2000-07-01

    One of the largest problems that we will have to deal with on this planet this millennium is to stop the pollution of our environment. In many of the ongoing works to reduce toxic emissions, gas sensors capable of enduring rough environments and high temperatures, would be a great tool. The different applications where sensors like this would be useful vary between everything from online measurement in the paper industry and food industry to measurement in the exhaust pipe of a car. In my project we have tested Schottky diodes and MlSiCFET sensor as gas sensors operating at high temperatures. The measurement condition in the exhaust pipe of a car is extremely tough, not only is the temperature high and the different gases quite harmful, there are also a lot of particles that can affect the sensors in an undesirable way. In my project we have been testing Schottky diodes and MlSiCFET sensors based on SiC as high temperature sensors, both in the laboratory with simulated exhaust and after a real engine. In this thesis we conclude that these sensors can work in the hostile environment of an engines exhaust. It is shown that when measuring in a gas mixture with a fixed I below one, where the I-value is controlled by the O{sub 2} concentration, a sensor with a catalytic gate metal as sensitive material respond more to the increased O{sub 2} concentration than the increased HC concentration when varying the two correspondingly. A number of different sensors have been tested in simulated exhaust towards NO{sub x}. It was shown that resistivity changes in the thin gate metal influenced the gas response. Tests have been performed where sensors were a part of a SCR system with promising results concerning NH{sub 3} sensitivity. With a working temperature of 300 deg C there is no contamination of the metal surface.

  15. Interacting effects of elevated temperature and additional water on plant physiology and net ecosystem carbon fluxes in a high Arctic ecosystem

    Science.gov (United States)

    Maseyk, Kadmiel; Seibt, Ulrike; Lett, Céline; Lupascu, Massimo; Czimczik, Claudia; Sullivan, Patrick; Welker, Jeff

    2013-04-01

    Arctic ecosystems are experiencing temperature increases more strongly than the global average, and increases in precipitation are also expected amongst the climate impacts on this region in the future. These changes are expected to strongly influence plant physiology and soil biogeochemistry with subsequent implications for system carbon balance. We have investigated the effects of a long-term (10 years) increase in temperature, soil water and the combination of both on a tundra ecosystem at a field manipulation experiment in NW Greenland. Leaf gas exchange, chlorophyll fluorescence, carbon (C) and nitrogen (N) content and leaf isotopic composition, and leaf morphology were measured on Salix arctica plants in treatment and control plots in June-July 2011, and continuous measurements of net plant and soil fluxes of CO2 and water were made using automatic chambers coupled to a trace gas laser analyzer. Plants in the elevated temperature (T2) treatment had the highest photosynthetic capacity in terms of net CO2 assimilation rates and photosystem II efficiencies, and lowest rates of non-photochemical energy dissipation during photosynthesis. T2 plants also had the highest leaf N content, specific leaf area (SLA) and saturation light level of photosynthesis. It appears that warming increases soil N availability, which the plants direct towards increasing photosynthetic capacity and producing larger thinner leaves. On the other hand, the plants in the plots with both elevated temperatures and additional water (T2W) had the lowest photosystem II efficiencies and the highest rates of non-photochemical energy dissipation, due more to higher levels of constitutive energy dissipation than regulated thermal quenching. Watering, both in combination with higher temperatures and alone (W treatment), also reduced leaf SLA and leaf N relative to control plots. However, net photosynthetic rates remained similar to control plants, due in part to higher stomatal conductance (W) and

  16. NOvel Refractory Materials for High Alkali, High Temperature Environments

    Energy Technology Data Exchange (ETDEWEB)

    Hemrick, J.G.; Griffin, R. (MINTEQ International, Inc.)

    2011-08-30

    Refractory materials can be limited in their application by many factors including chemical reactions between the service environment and the refractory material, mechanical degradation of the refractory material by the service environment, temperature limitations on the use of a particular refractory material, and the inability to install or repair the refractory material in a cost effective manner or while the vessel was in service. The objective of this project was to address the need for new innovative refractory compositions by developing a family of novel MgO-Al2O3 spinel or other similar magnesia/alumina containing unshaped refractory composition (castables, gunnables, shotcretes, etc) utilizing new aggregate materials, bond systems, protective coatings, and phase formation techniques (in-situ phase formation, altered conversion temperatures, accelerated reactions, etc). This family of refractory compositions would then be tailored for use in high-temperature, highalkaline industrial environments like those found in the aluminum, chemical, forest products, glass, and steel industries. A research team was formed to carry out the proposed work led by Oak Ridge National Laboratory (ORNL) and was comprised of the academic institution Missouri University of Science and Technology (MS&T), and the industrial company MINTEQ International, Inc. (MINTEQ), along with representatives from the aluminum, chemical, glass, and forest products industries. The two goals of this project were to produce novel refractory compositions which will allow for improved energy efficiency and to develop new refractory application techniques which would improve the speed of installation. Also methods of hot installation were sought which would allow for hot repairs and on-line maintenance leading to reduced process downtimes and eliminating the need to cool and reheat process vessels.

  17. Effect of simultaneous ion irradiation on microstructural change of SiC/SiC composites at high temperature

    Science.gov (United States)

    Taguchi, T.; Wakai, E.; Igawa, N.; Nogami, S.; Snead, L. L.; Hasegawa, A.; Jitsukawa, S.

    2002-12-01

    The effect of simultaneous triple ion irradiation of He, H and Si on microstructural evolution of two kinds of SiC/SiC composites (HNS composite (using Hi-Nicalon type S SiC fiber) and TSA composite (using Tyranno SA SiC fiber)) at 1000 °C has been investigated. The microstructure observations of SiC/SiC composites irradiated to 10 dpa were examined by transmission electron microscopy. He bubbles were hardly formed in matrix of TSA composite, but many helium bubbles and some cracks were observed at grain boundaries of matrix of HNS composite. He bubbles and cracks were not, on the other hand, observed in the both fiber fabrics of HNS and TSA composites. Debonding between fiber and carbon layer following irradiation region was not observed in the both composites. Under these irradiation conditions, TSA composite showed the better microstructural stability against ion beams irradiation than one of HNS composite.

  18. High Temperature Polymer Electrolyte Fuel Cells

    DEFF Research Database (Denmark)

    Fleige, Michael

    This thesis presents the development and application of electrochemical half-cell setups to study the catalytic reactions taking place in High Temperature Polymer Electrolyte Fuel Cells (HTPEM-FCs): (i) a pressurized electrochemical cell with integrated magnetically coupled rotating disk electrode...... to 140 ºC and oxygen pressures up to ~100 bar at room temperature. The GDE cell is successfully tested at 130 ºC by means of direct oxidation of methanol and ethanol, respectively. In the second part of the thesis, the emphasis is put on the ORR in H3PO4 with particular focus on the mass transport...... oxidation of ethanol is in principle a promising concept to supply HTPEM-FCs with a sustainable and on large scale available fuel (ethanol from biomass). However, the intermediate temperature tests in the GDE setup show that even on Pt-based catalysts the reaction rates become first significant...

  19. Characteristics of lactic acid bacteria isolates and their effect on the fermentation quality of Napier grass silage at three high temperatures.

    Science.gov (United States)

    Gulfam, Ali; Guo, Gang; Tajebe, Seare; Chen, Lei; Liu, Qinhua; Yuan, Xianjun; Bai, Yunfeng; Saho, Tao

    2017-04-01

    The poor fermentation quality of silage is an important issue for silage production during the high temperatures of summer. Pediococcus acidilactici GG13 (GG13) and Lactobacillus rhamnosus GG26 (GG26) isolated from Italian ryegrass (Lolium multiflorum Lam.) silage were characterised by morphological and physiological tests and 16S rRNA sequencing analysis, and their effects, along with those of a commercial lactic acid bacteria (LAB) inoculant (CB), on the fermentation quality of facultative halophyte Napier grass (Pennisetum purpureum Schumach) ensiled at 30 °C, 40 °C and 50 °C were studied, respectively. The strains GG13 and GG26 grew well at 50 °C and pH 3.5, and were tolerant to 6.5% NaCl. After ensiling for 50 days, the strains GG13 and GG26 and the CB decreased (P fermentation quality at 50 °C, whereas both isolated strains improved the fermentation quality of Napier grass silage as indicated by the lower (P fermentation quality of Napier grass silage. The results of this study suggested that strain GG13 is a good LAB inoculant for producing well-fermented silages during the high temperatures of summer times. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  20. Effects of helium on ductile brittle transition behavior of reduced activation ferritic steels after high concentration he implantation at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, A.; Ejiri, M.; Nogami, S.; Ishiga, M.; Abe, K. [Tohoku Univ., Dept. of Quantum Science and Energy Engr, Sendai (Japan); Kasada, R.; Kimura, A. [Kyoto Univ., Institute of Advanced Energy (Japan); Jitsukawa, S. [Japan Atomic Energy Agency, Tokai-mura, Naga-gun, Ibaraki-ken (Japan)

    2007-07-01

    Full text of publication follows: Influence of Helium (He) on fracture behavior of reduced activation ferritic/martensitic steels including Oxide Dispersion Strengthening (ODS) steels and F82H were examined. To study the He effects on fracture behavior of these steels after He bubble formation conditions, higher concentration of He implantation at around 550 C were performed and examined the relationship between microstructure evolution and fracture behavior of the steels. The 1.5CVN mini size Charpy specimens were used to evaluate impact test behavior. Reduced activation ferritic ODS steels, 9Cr-ODS and 12Cr-ODS steels were examine. F82H was also examined as reference material. Helium implantation was performed by a cyclotron of Tohoku University with a beam of 50 MeV {alpha}-particles at temperature around 550 C. A tandem-type energy degrader system was used to implant He into the specimen from the irradiated surface to the range of 50 MeV {alpha}-particles, that was about 380 {mu}m in iron. Implanted He concentration were about 1000 appm. Charpy impact test was performed using a instrumented impact test apparatus in Oarai branch of IMR, Tohoku University. Analyses of absorbed energy change and fracture surface were carried out. Vickers hardness test was also carried out on He implanted area of the 1.5CVN specimen to estimate irradiation hardening. Microstructural observation was performed by TEM. In the case of F82H, DBTT increased by the 1000 appm He implantation condition was about 80 C and grain boundary fracture surface was only observed in the He implanted area of all the ruptured specimens in brittle manner. On the other hand, DBTT shift and fracture mode change of He implanted 9Cr-ODS steel was not observed after He implantation. Microstructural observation showed that He bubble formation on the lath boundaries and grain boundaries were significant in F82H, but the bubble segregation on grain boundary in ODS steel was not apparent. The bubble formation

  1. Quench in high temperature superconductor magnets

    CERN Document Server

    Schwartz, J.

    2013-01-01

    High field superconducting magnets using high temperature superconductors are being developed for high energy physics, nuclear magnetic resonance and energy storage applications. Although the conductor technology has progressed to the point where such large magnets can be readily envisioned, quench protection remains a key challenge. It is well-established that quench propagation in HTS magnets is very slow and this brings new challenges that must be addressed. In this paper, these challenges are discussed and potential solutions, driven by new technologies such as optical fiber based sensors and thermally conducting electrical insulators, are reviewed.

  2. Effects of high-temperature diluted-H2 annealing on effective mobility of SiC MOSFETs estimated by split capacitance-voltage technique

    Science.gov (United States)

    Hirai, Hirohisa; Kita, Koji

    2017-11-01

    The effects of post-oxidation annealing (POA) in diluted-H2 ambient on 4H- and 6H-SiC/SiO2 interfaces were investigated. Effective mobility (μeff) was extracted from lateral metal-oxide-semiconductor field-effect transistors (MOSFETs) by the split capacitance-voltage (C-V) technique to determine the surface charge density and a calibration technique using two MOSFETs with different gate lengths to minimize the contribution of parasitic components. POA at 1150 °C in diluted-H2 ambient resulted in an enhancement of μeff, compared with that in N2 ambient. It was indicated that the effects of POA in diluted-H2 ambient should be attributed to the reduction in the density of near-interface traps in oxide, which disturb the electron transportation in the inversion channel, from the measurement temperature dependence of μeff for 6H-SiC MOSFETs as well as from the C-V curves of MOS capacitors fabricated on n-type 4H-SiC.

  3. High temperature deformation of silicon steel

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Calvillo, Pablo, E-mail: pablo.rodriguez@ctm.com.es [CTM - Technologic Centre, Materials Technology Area, Manresa, Cataluna (Spain); Department of Materials Science and Metallurgical Engineering, Universidad Politecnica de Cataluna, Barcelona (Spain); Houbaert, Yvan, E-mail: Yvan.Houbaert@UGent.be [Department of Materials Science and Engineering, University of Ghent (Belgium); Petrov, Roumen, E-mail: Roumen.Petrov@ugent.be [Department of Materials Science and Engineering, University of Ghent (Belgium); Kestens, Leo, E-mail: Leo.kestens@ugent.be [Department of Materials Science and Engineering, University of Ghent (Belgium); Colas, Rafael, E-mail: rafael.colas@uanl.edu.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico)

    2012-10-15

    The microstructure and texture development during high temperature plane strain compression of 2% in weight silicon steel was studied. The tests were carried out at a constant strain rate of 5 s{sup -1} with reductions of 25, 35 and 75% at temperatures varying from 800 to 1100 Degree-Sign C. The changes in microstructure and texture were studied by means of scanning electron microscopy and electron backscattered diffraction. The microstructure close to the surface of the samples was equiaxed, which is attributed to the shear caused by friction, whereas that at the centre of the specimens was made of a mixture of elongated and fine equiaxed grains, the last ones attributed to the action of dynamic recovery followed by recrystallization. It was found that the volume fraction of these equiaxed grains augmented as reduction and temperature increased; a 0.7 volume fraction was accomplished with a 75% reduction at 1100 Degree-Sign C. The texture of the equiaxed and elongated grains was found to vary with the increase of deformation and temperature, as the {gamma}-fibre tends to disappear and the {alpha}-fibre to increase towards the higher temperature range. -- Highlights: Black-Right-Pointing-Pointer The plastic deformation of a silicon containing steel is studied by plane strain compression. Black-Right-Pointing-Pointer Equiaxed and elongated grains develop in different regions of the sample due to recrystallization. Black-Right-Pointing-Pointer Texture, by EBSD, is revealed to be similar in either type of grains.

  4. Effective Energy Transfer via Plasmon-Activated High-Energy Water Promotes Its Fundamental Activities of Solubility, Ionic Conductivity, and Extraction at Room Temperature

    National Research Council Canada - National Science Library

    Yang, Chih-Ping; Chen, Hsiao-Chien; Wang, Ching-Chiung; Tsai, Po-Wei; Ho, Chia-Wen; Liu, Yu-Chuan

    2015-01-01

    ... conductivity, and extraction at room temperature. High-energy water with reduced HBs was created by utilizing hot electrons with energies from the decay of surface plasmon excited at gold (Au) nanoparticles (NPs...

  5. Effects of composite scale on high temperature oxidation resistance of Fe-Cr-Ni heat resistant alloy

    Directory of Open Access Journals (Sweden)

    Wang Haitao

    2009-05-01

    Full Text Available Fe-Cr-Ni heat resistant alloys with aluminum and silicon addition, alone and in combination, were melted using an intermediate frequency induction furnace with a non-oxidation method. By the oxidation weight gain method, the oxidation resistances of the test alloys were determined at 1,200 ìC for 500 hours. According to the oxidation weight gains, the oxidation kinetic curves were plotted and the functions were regressed by the least squares method. The results show that the oxidation kinetic curves follow the power function of y = axb (a>0, 0effects of scale compositions on oxidation resistance were studied further by analyses using X-ray diffraction (XRD and scanning electron microscope (SEM. It is found that the composite scale compounds of Cr2O3, メ-Al2O3, SiO2 and FeCr2O4, with compact structure and tiny grains, shows complete oxidation resistance at 1,200 ìC. When the composite scale lacks メ-Al2O3 or SiO2, it becomes weak in oxidation resistance with a loose structure. By the criterion of standard Gibbs formation free energy, the model of the nucleation and growth of the composite scale is established. The forming of the composite scale is the result of the competition of being oxidized and reduced between aluminum, silicon and the matrix metal elements of iron, chromium and nickel. The protection of the composite scale is analyzed essentially by electrical conductivity and strength properties.

  6. Vapor phase lubrication of high temperature alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hanyaloglu, B.F.; Graham, E.E.; Oreskovic, T.; Hajj, C.G. [Cleveland State Univ., OH (United States)

    1995-06-01

    In a previous study, it was found that when a nickel-based superalloy IN750 was heated to high temperatures, a passive layer of aluminum oxide formed on the surface, preventing vapor phase lubrication. In this study, two nickel-chrome-iron alloys and a nickel-copper alloy were studied for high temperature lubrication to see if these alloys, which contained small amounts of aluminum, would exhibit similar behavior. It was found that under static conditions, all three alloys formed a lubricious nodular coating when exposed to a vapor of aryl phosphate. Under dynamic sliding conditions at 500{degrees}C, these alloys were successfully lubricated with a coefficient of friction of 0.1 and no detectable wear. In order to explain these results, a direct correlation between successful vapor phase lubrication and the composition of the alloys containing aluminum has been proposed. If the ratio of copper/aluminum or iron/aluminum is greater that 100 vapor phase, lubrication will be successful. If the ratio is less than 10, a passive aluminum oxide layer will prevent vapor phase lubrication. By selecting alloys with a high iron or copper content, vapor phase lubrication can provide excellent lubrication at high temperatures. 14 refs., 11 figs., 1 tab.

  7. Medium Deep High Temperature Heat Storage

    Science.gov (United States)

    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.

  8. The effect of pressurization path on high pressure gas forming of Ti-3Al-2.5V at elevated temperature

    OpenAIRE

    Liu Gang; Wang Jianlong; Dang Kexin; Yuan Shijian

    2015-01-01

    High pressure gas forming is a tubular component forming technology with pressurized gas at elevated temperature, based on QPF, HMGF and Hydroforming. This process can be used to form tube blank at lower temperatures with high energy efficiency and also at higher strain rates. With Ti-3Al-2.5V Ti-alloy tube, the potential of HPGF was studied further through experiments at the elevated temperatures of 650 ∘C and 700 ∘C. In order to know the formability of the Ti-alloy tube, tensile tests were ...

  9. High temperature superconductors for magnetic suspension applications

    Science.gov (United States)

    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.

  10. Metallic Membranes for High Temperature Hydrogen Separation

    DEFF Research Database (Denmark)

    Ma, Y.H.; Catalano, Jacopo; Guazzone, Federico

    2013-01-01

    Composite palladium membranes have extensively been studied in laboratories and, more recently, in small pilot industrial applications for the high temperature separation of hydrogen from reactant mixtures such as water-gas shift (WGS) reaction or methane steam reforming (MSR). Composite Pd...... membrane fabrication methods have matured over the last decades, and the deposition of very thin films (1–5 µm) of Pd over porous ceramics or modified porous metal supports is quite common. The H2 permeances and the selectivities achieved at 400–500 °C were in the order of 50–100 Nm3/m/h/bar0.5 and greater...... than 1000, respectively. This chapter describes in detail composite Pd-based membrane preparation methods, which consist of the grading of the support and the deposition of the dense metal layer, their performances, and their applications in catalytic membrane reactors (CMRs) at high temperatures (400...

  11. High Temperature Phenomena in Shock Waves

    CERN Document Server

    2012-01-01

    The high temperatures generated in gases by shock waves give rise to physical and chemical phenomena such as molecular vibrational excitation, dissociation, ionization, chemical reactions and inherently related radiation. In continuum regime, these processes start from the wave front, so that generally the gaseous media behind shock waves may be in a thermodynamic and chemical non-equilibrium state. This book presents the state of knowledge of these phenomena. Thus, the thermodynamic properties of high temperature gases, including the plasma state are described, as well as the kinetics of the various chemical phenomena cited above. Numerous results of measurement and computation of vibrational relaxation times, dissociation and reaction rate constants are given, and various ionization and radiative mechanisms and processes are presented. The coupling between these different phenomena is taken into account as well as their interaction with the flow-field. Particular points such as the case of rarefied flows an...

  12. Trends in Surface Temperature at High Latitudes

    Science.gov (United States)

    Comiso, Josefino C.

    2012-01-01

    The earliest signal of a climate change is expected to be found in the polar regions where warming is expected to be amplified on account of ice-albedo feedbacks associated with the high reflectivity of snow and ice. Because of general inaccessibility, there is a general paucity of in situ data and hence the need to use satellite data to observe the large-scale variability and trends in surface temperature in the region. Among the most important sensors for monitoring surface temperature has been the Advanced Very High Resolution Radiometer (AVHRR) which was first launched in 1978 and has provided continuous thermal infrared data since 1981. The top of the atmosphere data are converted to surface temperature data through various schemes that accounts for the unique atmospheric and surface conditions in the polar regions. Among the highest source of error in the data is cloud masking which is made more difficult in the polar region because of similar Signatures of clouds and snow lice covered areas. The availability of many more channels in the Moderate Resolution Imaging Spectroradiometer (MODIS) launched on board Terra satellite in December 1999 and on board Aqua in May 2002 (e.g., 36 visible and infrared channels compared to 5 for AVHRR) made it possible to minimize the error. Further capabilities were introduced with the Advanced Microwave Scanning Radiometer (AMSR) which has the appropriate frequency channels for the retrieval of sea surface temperature (SST). The results of analysis of the data show an amplified warming in the Arctic region, compared with global warming. The spatial distribution of warming is, however, not uniform and during the last 3 decades, positive temperature anomalies have been most pronounced in North America, Greenland and the Arctic basin. Some regions of the Arctic such as Siberia and the Bering Sea surprisingly show moderate cooling but this may be because these regions were anomalously warm in the 1980s when the satellite record

  13. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed only electromagnets. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

  14. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed electromagnets only. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

  15. Quantifying Temperature Effects on Fall Chinook Salmon

    Energy Technology Data Exchange (ETDEWEB)

    Jager, Yetta [ORNL

    2011-11-01

    The motivation for this study was to recommend relationships for use in a model of San Joaquin fall Chinook salmon. This report reviews literature pertaining to relationships between water temperature and fall Chinook salmon. The report is organized into three sections that deal with temperature effects on development and timing of freshwater life stages, temperature effects on incubation survival for eggs and alevin, and temperature effects on juvenile survival. Recommendations are made for modeling temperature influences for all three life stages.

  16. High temperature impedance spectroscopy of barium stannate ...

    Indian Academy of Sciences (India)

    Abstract. Polycrystalline powder of BaSnO3 was prepared at 1300 ◦C using a high-temperature solid-state reac- tion technique. X-ray diffraction analysis indicated the formation of a single-phase cubic structure with lattice parameter: a = (4·1158 ± 0·0003) Å. The synthesized powder was characterized using X-ray diffraction ...

  17. High temperature mechanical properties of iron aluminides

    Directory of Open Access Journals (Sweden)

    Morris, D. G.

    2001-04-01

    Full Text Available Considerable attention has been given to the iron aluminide family of intermetallics over the past years since they offer considerable potential as engineering materials for intermediate to high temperature applications, particularly in cases where extreme oxidation or corrosion resistance is required. Despite efforts at alloy development, however, high temperature strength remains low and creep resistance poor. Reasons for the poor high-temperature strength of iron aluminides will be discussed, based on the ordered crystal structure, the dislocation structure found in the material, and the mechanisms of dislocation pinning operating. Alternative ways of improving high temperature strength by microstructural modification and the inclusion of second phase particles will also be considered.

    Durante los últimos años se ha prestado mucha atención a la familia de intermetálicos Fe-Al, puesto que estos constituyen un considerable potencial como materiales de ingeniería en aplicaciones a temperaturas intermedias o altas, sobre todo en casos donde se necesita alta resistencia a la oxidación o corrosión. A pesar del considerable esfuerzo desarrollado para obtener aleaciones con mejores propiedades, su resistencia mecánica a alta temperatura no es muy elevada. Se discutirán los aspectos que contribuyen a la baja resistencia mecánica a temperatura elevada en función de la estructura de dislocaciones y los mecanismos de anclaje que operan en este intermetálico. Se considerarán, también, maneras alternativas para mejorar la resistencia a temperatura elevada mediante la modificación de la microestructura y la incorporación de partículas de segunda fase.

  18. Thermal fuse for high-temperature batteries

    Science.gov (United States)

    Jungst, Rudolph G.; Armijo, James R.; Frear, Darrel R.

    2000-01-01

    A thermal fuse, preferably for a high-temperature battery, comprising leads and a body therebetween having a melting point between approximately 400.degree. C. and 500.degree. C. The body is preferably an alloy of Ag--Mg, Ag--Sb, Al--Ge, Au--In, Bi--Te, Cd--Sb, Cu--Mg, In--Sb, Mg--Pb, Pb--Pd, Sb--Zn, Sn--Te, or Mg--Al.

  19. High-Temperature Thermoelectric Energy Conversion

    Science.gov (United States)

    Wood, C.

    1987-01-01

    Theory of thermoelectric energy conversion at high temperatures and status of research on conversion materials reviewed in report. Shows highest values of thermoelectric figure of merit, Z, found in semiconductor materials. Semiconductors keep wide choice of elements and compounds. Electrical properties tailored to particular application by impurity doping and control of stoichiometry. Report develops definition of Z useful for comparing materials and uses it to evaluate potentials of different classes of materialsmetals, semiconductors, and insulators.

  20. High Temperature Perforating System for Geothermal Applications

    Energy Technology Data Exchange (ETDEWEB)

    Smart, Moises E. [Schlumberger Technology Corporation, Sugar Land, TX (United States)

    2017-02-28

    The objective of this project is to develop a perforating system consisting of all the explosive components and hardware, capable of reliable performance in high temperatures geothermal wells (>200 ºC). In this light we will focused on engineering development of these components, characterization of the explosive raw powder and developing the internal infrastructure to increase the production of the explosive from laboratory scale to industrial scale.