WorldWideScience

Sample records for thermal effects

  1. Effects of water and sawdust additives on thermal effusivity, thermal ...

    African Journals Online (AJOL)

    The effects of water and sawdust additives on the thermal effusivity (e), thermal conductivity (λ), and durability of cement-stabilized laterites were investigated. The thermal effusivity (e) and conductivity(λ) have direct influ-ence on heat transfer and thermal insulation in buildings, and the parameters were determined by hot ...

  2. Thermal effects in supercapacitors

    CERN Document Server

    Xiong, Guoping; Fisher, Timothy S

    2015-01-01

    This Brief reviews contemporary research conducted in university and industry laboratories on thermal management in electrochemical energy storage systems (capacitors and batteries) that have been widely used as power sources in many practical applications, such as automobiles, hybrid transport, renewable energy installations, power backup and electronic devices. Placing a particular emphasis on supercapacitors, the authors discuss how supercapacitors, or ultra capacitors, are complementing and  replacing, batteries because of their faster power delivery, longer life cycle and higher coulombic efficiency, while providing higher energy density than conventional electrolytic capacitors. Recent advances in both macro- and micro capacitor technologies are covered. The work facilitates systematic understanding of thermal transport in such devices that can help develop better power management systems.

  3. The Effect of Core Configuration on Thermal Barrier Thermal Performance

    Science.gov (United States)

    DeMange, Jeffrey J.; Bott, Robert H.; Druesedow, Anne S.

    2015-01-01

    Thermal barriers and seals are integral components in the thermal protection systems (TPS) of nearly all aerospace vehicles. They are used to minimize heat transfer through interfaces and gaps and protect underlying temperature-sensitive components. The core insulation has a significant impact on both the thermal and mechanical properties of compliant thermal barriers. Proper selection of an appropriate core configuration to mitigate conductive, convective and radiative heat transfer through the thermal barrier is challenging. Additionally, optimization of the thermal barrier for thermal performance may have counteracting effects on mechanical performance. Experimental evaluations have been conducted to better understand the effect of insulation density on permeability and leakage performance, which can significantly impact the resistance to convective heat transfer. The effect of core density on mechanical performance was also previously investigated and will be reviewed. Simple thermal models were also developed to determine the impact of various core parameters on downstream temperatures. An extended understanding of these factors can improve the ability to design and implement these critical TPS components.

  4. Giant thermal Hall effect in multiferroics

    Science.gov (United States)

    Ideue, T.; Kurumaji, T.; Ishiwata, S.; Tokura, Y.

    2017-08-01

    Multiferroics, in which dielectric and magnetic orders coexist and couple with each other, attract renewed interest for their cross-correlated phenomena, offering a fundamental platform for novel functionalities. Elementary excitations in such systems are strongly affected by the lattice-spin interaction, as exemplified by the electromagnons and the magneto-thermal transport. Here we report an unprecedented coupling between magnetism and phonons in multiferroics, namely, the giant thermal Hall effect. The thermal transport of insulating polar magnets (ZnxFe1-x)2Mo3O8 is dominated by phonons, yet extremely sensitive to the magnetic structure. In particular, large thermal Hall conductivities are observed in the ferrimagnetic phase, indicating unconventional lattice-spin interactions and a new mechanism for the Hall effect in insulators. Our results show that the thermal Hall effect in multiferroic materials can be an effective probe for strong lattice-spin interactions and provide a new tool for magnetic control of thermal currents.

  5. Effective thermal conductivity of condensed polymeric nanofluids ...

    Indian Academy of Sciences (India)

    ... scattering at matrix–particle boundaries. These two mechanisms are combined to arrive at an expression for their effective thermal conductivity. Analysis of the results reveals the possibility to tune the thermal conductivity of such nanosolids over a wide range using the right types of nanoparticles and right concentration.

  6. Thermal Bridge Effects in Walls Separating Rowhouses

    DEFF Research Database (Denmark)

    Rose, Jørgen

    1997-01-01

    In this report the thermal bridge effects at internal wall/roof junctions in rowhouses are evaluated. The analysis is performed using a numerical calculation programme, and different solutions are evaluated with respect to extra heat loss and internal surface temperatures.......In this report the thermal bridge effects at internal wall/roof junctions in rowhouses are evaluated. The analysis is performed using a numerical calculation programme, and different solutions are evaluated with respect to extra heat loss and internal surface temperatures....

  7. Thermal effects on PLATO point spread function

    Science.gov (United States)

    Gullieuszik, Marco; Magrin, Demetrio; Greggio, Davide; Ragazzoni, Roberto; Nascimbeni, Valerio; Bergomi, Maria; Biondi, Federico; Chinellato, Simonetta; Dima, Marco; Farinato, Jacopo; Marafatto, Luca; Viotto, Valentina; Munari, Matteo; Pagano, Isabella; Sicilia, Daniela; Basso, Stefano; Borsa, Francesco; Ghigo, Mauro; Spiga, Daniele; Bandy, Thimoty; Benz, Willy; Brändli, Mathias; Bruno, Giordano; De Roche, Thierry; Piazza, Daniele; Rieder, Martin; Brandeker, Alexis; Klebor, Maximilian; Mogulsky, Valery; Schweitzer, Mario; Wieser, Matthias; Erikson, Anders; Rauer, Heike

    2016-07-01

    Thermal effects in PLATO are analyzed in terms of uniform temperature variations, longitudinal and lateral temperature gradients. We characterize these effects by evaluating the PSF centroid shifts and the Enclosed Energy variations across the whole FoV. These patterns can then be used to gauge the thermal behavior of each individual telescope in order to improve the local photometric calibration across the PLATO field of view.

  8. Thermal Bridge Effects in Window Grooves

    DEFF Research Database (Denmark)

    Rose, Jørgen

    1997-01-01

    In this report thermal bridge effects in window grooves are analyzed. The analysis is performed using different thicknesses of the window groove insulation, to evaluate what the optimal solution is.All analysis in the report is performed using both 2- and 3-dimensional numerical analysis....

  9. Microlevel thermal effects in metal matrix composites

    Science.gov (United States)

    Herakovich, Carl T.

    1990-01-01

    A method for studying the influence of thermal effects on the inelastic response of metal matrix composites is reviewed. A micromechanics approach based upon the method of cells is shown to be quite versatile for studying a variety of materials response phenomena. Yielding and inelastic response of the composite are predicted as functions of thermal stresses, yielding of the matrix, and imperfect fiber/matrix bonding. Results are presented in the form of yield surfaces and nonlinear stress-strain curves for unidirectional and laminated boron/aluminum and silicon-carbide/titanium.

  10. 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)

  11. Scaling thermal effects in radial flow

    Science.gov (United States)

    Hudspeth, R. T.; Guenther, R. B.; Roley, K. L.; McDougal, W. G.

    To adequately evaluate the environmental impact of siting nuclear waste repositories in basalt aquicludes, it is essential to know the effects on parameter identification algorithms of thermal gradients that exist in these basaltic aquicludes. Temperatures of approximately 60°C and pressures of approximately 150 atm can be expected at potential repository sites located at depths of approximately 1000 m. The phenomenon of over-recovery has been observed in some pumping tests conducted at the Hanford Nuclear Reservation located in the Pasco Basin adjacent to the Columbia River in the state of Washington, USA. This over-recovery phenomenon may possibly be due to variations in the fluid density caused by thermal gradients. To assess the potential effects of these thermal gradients on indirect parameter identification algorithms, a systematic scaling of the governing field equations is required in order to obtain dimensionless equations based on the principle of similarity. The constitutive relationships for the specific weight of the fluid and for the porosity of the aquiclude are shown to be exponentially dependent on the pressure gradient. The dynamic pressure is converted to the piezometric head and the flow equation for the piezometric head is then scaled in radial coordinates. Order-of-magnitude estimates are made for all variables in unsteady flow for a typical well test in a basaltic aquiclude. Retaining all nonlinear terms, the parametric dependency of the flow equation on the classical dimensionless thermal and hydraulic parameters is demonstrated. These classical parameters include the Batchelor, Fourier, Froude, Grashof, and Reynolds Numbers associated with thermal flows. The flow equation is linearized from order-of-magnitude estimates based on these classical parameters for application in parameter identification algorithms.

  12. Effects of insular stimulation on thermal nociception.

    Science.gov (United States)

    Denis, D J; Marouf, R; Rainville, P; Bouthillier, A; Nguyen, D K

    2016-05-01

    Electrical stimulation used for brain mapping in the postero-superior insula can evoke pain. The effects of prolonged high frequency insular stimulation on pain thresholds are unknown. Prolonged high frequency insular stimulation, by virtue of its inhibitory properties on networks, could decrease thermal nociception. Epileptic subjects had electrodes implanted in the insular cortex for the purpose of epileptic focus resection. Thermal and pressure nociceptive thresholds were tested bilaterally on the forearm on two consecutive days. Randomly assigned double-blind high frequency (150 Hz) insular stimulation took place for 10 min before pain testing either on the first day or on the second day. Six subjects (three females; mean age of 35 years) were included. Insular stimulation increased heat pain threshold on the ipsilateral (p = 0.003; n = 6) and contralateral sides (p = 0.047; n = 6). Differences in cold pain threshold did not reach statistical significance (ipsilateral: p = 0.341, contralateral: p = 0.143; n = 6), but one subject had a profound decrease in both heat and cold pain responses. Pressure pain threshold was not modified by insular stimulation (ipsilateral: p = 0.1123; contralateral: p = 0.1192; n = 6). Two of the three subjects who had a postero-superior operculo-insulectomy developed central pain with contralateral thermal nociceptive deficit. High frequency inhibitory postero-superior insular stimulation may have the potential to decrease thermal nociception. Together with previous studies, our data support the notion that the integrity of this brain region is necessary for thermal but not pressure nociceptive processing. © 2015 European Pain Federation - EFIC®

  13. Thermal effects in microfluidics with thermal conductivity spatially modulated

    Science.gov (United States)

    Vargas Toro, Agustín.

    2014-05-01

    A heat transfer model on a microfluidic is resolved analytically. The model describes a fluid at rest between two parallel plates where each plate is maintained at a differentially specified temperature and the thermal conductivity of the microfluidic is spatially modulated. The heat transfer model in such micro-hydrostatic configuration is analytically resolved using the technique of the Laplace transform applying the Bromwich Integral and the Residue theorem. The temperature outline in the microfluidic is presented as an infinite series of Bessel functions. It is shown that the result for the thermal conductivity spatially modulated has as a particular case the solution when the thermal conductivity is spatially constant. All computations were performed using the computer algebra software Maple. It is claimed that the analytical obtained results are important for the design of nanoscale devices with applications in biotechnology. Furthermore, it is suggested some future research lines such as the study of the heat transfer model in a microfluidic resting between coaxial cylinders with radially modulated thermal conductivity in order to achieve future developments in this area.

  14. Thermal stress effects in intermetallic matrix composites

    Science.gov (United States)

    Wright, P. K.; Sensmeier, M. D.; Kupperman, D. S.; Wadley, H. N. G.

    1993-01-01

    Intermetallic matrix composites develop residual stresses from the large thermal expansion mismatch (delta-alpha) between the fibers and matrix. This work was undertaken to: establish improved techniques to measure these thermal stresses in IMC's; determine residual stresses in a variety of IMC systems by experiments and modeling; and, determine the effect of residual stresses on selected mechanical properties of an IMC. X ray diffraction (XRD), neutron diffraction (ND), synchrotron XRD (SXRD), and ultrasonics (US) techniques for measuring thermal stresses in IMC were examined and ND was selected as the most promising technique. ND was demonstrated on a variety of IMC systems encompassing Ti- and Ni-base matrices, SiC, W, and Al2O3 fibers, and different fiber fractions (Vf). Experimental results on these systems agreed with predictions of a concentric cylinder model. In SiC/Ti-base systems, little yielding was found and stresses were controlled primarily by delta-alpha and Vf. In Ni-base matrix systems, yield strength of the matrix and Vf controlled stress levels. The longitudinal residual stresses in SCS-6/Ti-24Al-llNb composite were modified by thermomechanical processing. Increasing residual stress decreased ultimate tensile strength in agreement with model predictions. Fiber pushout strength showed an unexpected inverse correlation with residual stress. In-plane shear yield strength showed no dependence on residual stress. Higher levels of residual tension led to higher fatigue crack growth rates, as suggested by matrix mean stress effects.

  15. Artificial Retina Project: Electromagnetic and Thermal Effects

    Energy Technology Data Exchange (ETDEWEB)

    Lazzi, Gianluca

    2014-08-29

    This award supported the investigation on electromagnetic and thermal effects associated with the artificial retina, designed in collaboration with national laboratories, universities, and private companies. Our work over the two years of support under this award has focused mainly on 1) Design of new telemetry coils for optimal power and data transfer between the implant and the external device while achieving a significant size reduction with respect to currently used coils; 2) feasibility study of the virtual electrode configuration 3) study the effect of pulse shape and duration on the stimulation efficacy.

  16. Effective thermal conductivity of a thin composite material

    Energy Technology Data Exchange (ETDEWEB)

    Phelan, P.E. [Arizona State Univ., Tempe, AZ (United States). Dept. of Mechanical and Aerospace Engineering; Niemann, R.C. [Argonne National Lab., IL (United States)

    1996-12-31

    The thermal conductivity of a randomly oriented composite material is modeled using a probabilistic approach in order to determine if a size effect exists for the thermal conductivity at small composite thickness. The numerical scheme employs a random number generator to position the filler elements, which have a relatively high thermal conductivity, within a matrix having a relatively low thermal conductivity. Results indicate that, below some threshold thickness, the composite thermal conductivity increases with decreasing thickness, while above the threshold the thermal conductivity is independent of thickness. The threshold thickness increases for increasing filler fraction and increasing k{sub f}/k{sub m}, the ratio between filler and matrix thermal conductivities.

  17. Physical effects of thermal pollution in lakes

    Science.gov (United States)

    Râman Vinnâ, Love; Wüest, Alfred; Bouffard, Damien

    2017-05-01

    Anthropogenic heat emissions into inland waters influence water temperature and affect stratification, heat and nutrient fluxes, deep water renewal, and biota. Given the increased thermal stress on these systems by growing cooling demands of riparian/coastal infrastructures in combination with climate warming, the question arises on how to best monitor and manage these systems. In this study, we investigate local and system-wide physical effects on the medium-sized perialpine Lake Biel (Switzerland), influenced by point-source cooling water emission from an upstream nuclear power plant (heat emission ˜700 MW, ˜18 W m-2 lake wide). We use one-dimensional (SIMSTRAT) and three-dimensional (Delft3D-Flow) hydrodynamic numerical simulations and provide model resolution guidelines for future studies of thermal pollution. The effects on Lake Biel by the emitted excess heat are summarized as: (i) clear seasonal trend in temperature increase, locally up to 3.4°C and system-wide volume mean ˜0.3°C, which corresponds to one decade of regional surface water climate warming; (ii) the majority of supplied thermal pollution (˜60%) leaves this short residence time (˜58 days) system via the main outlet, whereas the remaining heat exits to the atmosphere; (iii) increased length of stratified period due to the stabilizing effects of additional heat; (iv) system-wide effects such as warmer temperature, prolonged stratified period, and river-caused epilimnion flushing are resolved by both models whereas local raised temperature and river short circuiting was only identifiable with the three-dimensional model approach. This model-based method provides an ideal tool to assess man-made impacts on lakes and their downstream outflows.

  18. The Effect of Thermal Mass on Annual Heat Load and Thermal Comfort in Cold Climate Construction

    DEFF Research Database (Denmark)

    Stevens, Vanessa; Kotol, Martin; Grunau, Bruno

    2016-01-01

    Thermal mass in building construction refers to a building material's ability to absorb and release heat based on changing environmental conditions. In building design, materials with high thermal mass used in climates with a diurnal temperature swing around the interior set-point temperature have...... been shown to reduce the annual heating demand. However, few studies exist regarding the effects of thermal mass in cold climates. The purpose of this research is to determine the effect of high thermal mass on the annual heat demand and thermal comfort in a typical Alaskan residence using energy...... that while increased thermal mass does have advantages in all climates, such as a decrease in summer overheating, it is not an effective strategy for decreasing annual heat demand in typical residential buildings in Alaska. (C) 2015 American Society of Civil Engineers....

  19. Effects of Screening on the Thermal Resistivity And Compressibility ...

    African Journals Online (AJOL)

    Models for computing thermal resistivity, compressibility ratio, and screening parameter of metals was developed and used to study the effects of screening on the thermal resistivity and compressibility ratio of metals. The results obtained revealed that the thermal resistivity of metals increases with an increase in the electron ...

  20. An effective thermal circuit model for electro-thermal simulation of SOI analog circuits

    Science.gov (United States)

    Cheng, Ming-C.; Zhang, Kun

    2011-08-01

    A physics-based thermal circuit model is developed for electro-thermal simulation of SOI analog circuits. The circuit model integrates a non-isothermal device thermal circuit with interconnect thermal networks and is validated with high accuracy against finite element simulations in different layout structures. The non-isothermal circuit model is implemented in BSIMSOI to account for self-heating effect (SHE) in a Spice simulator, and applied to electro-thermal simulation of an SOI cascode current mirror constructed using different layouts. Effects of layout design on electric and thermal behaviors are investigated in detail. Influences of BOX thickness are also examined. It has been shown that the proposed non-isothermal approach is able to effectively account for influences of layout design, self-heating, high temperature gradients along the islands, interconnect temperature distributions, thermal coupling, and heat losses via BOX and interconnects, etc., in SOI current mirror structures. The model provides basic concepts and thermal circuits that can be extended to develop an effective model for electro-thermal simulation of SOI analog ICs.

  1. Effect of thermal state and thermal comfort on cycling performance in the heat

    NARCIS (Netherlands)

    Schulze, E.; Daanen, H.A.M.; Levels, K.; Casadio, J.R.; Plews, D.J.; Kliding, A.E.; Siegel, R.; Laursen, P.B.

    2015-01-01

    Purpose: To determine the effect of thermal state and thermal comfort on cycling performance in the heat. Methods: Seven well-trained male triathletes completed 3 performance trials consisting of 60 min cycling at a fixed rating of perceived exertion (14) followed immediately by a 20-km time trial

  2. How to measure thermal effects of personal cooling systems : Human, thermal manikin and human simulator study

    NARCIS (Netherlands)

    Bogerd, N.; Psikuta, A.; Daanen, H.A.M.; Rossi, R.M.

    2010-01-01

    Thermal effects, such as cooling power and thermophysiological responses initiated upon application of a personal cooling system, can be assessed with (i) humans, (ii) a thermal manikin and (iii) a thermophysiological human simulator. In order to compare these methods, a cooling shirt (mild cooling)

  3. Transient thermal effects in Alpine permafrost

    Directory of Open Access Journals (Sweden)

    J. Noetzli

    2009-04-01

    Full Text Available In high mountain areas, permafrost is important because it influences the occurrence of natural hazards, because it has to be considered in construction practices, and because it is sensitive to climate change. The assessment of its distribution and evolution is challenging because of highly variable conditions at and below the surface, steep topography and varying climatic conditions. This paper presents a systematic investigation of effects of topography and climate variability that are important for subsurface temperatures in Alpine bedrock permafrost. We studied the effects of both, past and projected future ground surface temperature variations on the basis of numerical experimentation with simplified mountain topography in order to demonstrate the principal effects. The modeling approach applied combines a distributed surface energy balance model and a three-dimensional subsurface heat conduction scheme. Results show that the past climate variations that essentially influence present-day permafrost temperatures at depth of the idealized mountains are the last glacial period and the major fluctuations in the past millennium. Transient effects from projected future warming, however, are likely larger than those from past climate conditions because larger temperature changes at the surface occur in shorter time periods. We further demonstrate the accelerating influence of multi-lateral warming in steep and complex topography for a temperature signal entering the subsurface as compared to the situation in flat areas. The effects of varying and uncertain material properties (i.e., thermal properties, porosity, and freezing characteristics on the subsurface temperature field were examined in sensitivity studies. A considerable influence of latent heat due to water in low-porosity bedrock was only shown for simulations over time periods of decades to centuries. At the end, the model was applied to the topographic setting of the Matterhorn

  4. Thermal Radiation Effects on Thermal Explosion in Polydisperse Fuel Spray-Probabilistic Model

    Directory of Open Access Journals (Sweden)

    Ophir Navea

    2011-06-01

    Full Text Available We investigate the effect of thermal radiation on the dynamics of a thermal explosion of polydisperse fuel spray with a complete description of the chemistry via a single-step two-reactant model of general order. The polydisperse spray is modeled using a Probability Density Function (PDF. The thermal radiation energy exchange between the evaporation surface of the fuel droplets and the burning gas is described using the Marshak boundary conditions. An explicit expression of the critical condition for thermal explosion limit is derived analytically and represents a generalization of the critical parameter of the classical Semenov theory. Because we investigated the model in the range where the temperature is very high, the effect of the thermal radiation is significant.

  5. The coke drum thermal kinetic effects

    Energy Technology Data Exchange (ETDEWEB)

    Aldescu, Maria M.; Romero, Sim; Larson, Mel [KBC Advanced Technologies plc, Surrey (United Kingdom)

    2012-07-01

    The coke drum thermal kinetic dynamics fundamentally affect the coker unit yields as well as the coke product properties and unit reliability. In the drum the thermal cracking and polymerization or condensation reactions take place in a semi-batch environment. Understanding the fundamentals of the foaming kinetics that occur in the coke drums is key to avoiding a foam-over that could result in a unit shutdown for several months. Although the most dynamic changes with time occur during drum filling, other dynamics of the coker process will be discussed as well. KBC has contributed towards uncovering and modelling the complexities of heavy oil thermal dynamics. (author)

  6. The effect of leucite crystallization and thermal history on thermal expansion measurement of dental porcelains

    Science.gov (United States)

    Khajotia, Sharukh Soli

    1997-12-01

    Objectives. Measurement of thermal expansion in glassy materials is complicated by thermal history effects. The purpose of this research was to determine whether the occurrence of structural relaxation in glassy materials, such as dental porcelains, and changes in porcelain leucite content could interfere with the accurate measurement of the coefficient of thermal expansion during the thermal expansion measurement itself. Methods. In a randomized design, thermal expansion specimens were fabricated using six commercial body porcelains and the leucite-containing Component No. 1 frit (Weinstein et al. patent, 1962), and subjected to one of the following heat treatments: a single heating run at 3sp°C/min in a conventional dilatometer followed by air quenching; three successive low-rate heating and cooling thermal expansion runs at 3sp°C/min in a conventional dilatometer; or three successive high-rate heating and cooling thermal expansion runs at 600sp°C/min in a laser dilatometer. The remaining specimens were left untreated and served as controls. Potential changes in porcelain leucite content were monitored via quantitative X-ray diffraction. Thermal expansion data for each run over a temperature range of 25-500sp°C and the leucite content of all specimens were subjected to repeated measures analysis of variance. Results. The thermal expansion coefficient measured on first slow heating was significantly lower than the values for succeeding low-rate heating and cooling runs in all materials (p $ 0.05). No significant effect of dilatometer thermal treatments on leucite content (p >$ 0.05) was shown for all materials studied using both dilatometers. Significance. The crystallization of additional amounts of leucite during thermal expansion runs can be ruled out as a possible interference in the determination of the thermal expansion coefficient of dental porcelain. Conventional dilatometer measurements exhibited structural relaxation during the first heating run, as

  7. Effect of thermal treatment on Zn nanodisks

    Energy Technology Data Exchange (ETDEWEB)

    Acuña-Avila, Pedro E., E-mail: pacunaa004@alumno.uaemex.mx; López, Roberto; Vigueras-Santiago, Enrique; Hernández-López, Susana; Camacho-López, Marco [Laboratorio de Investigación y Desarrollo de Materiales Avanzados (LIDMA). Facultad de Química de la Universidad Autónoma del Estado de México. Paseo Colón esquina Paseo Tollocan C.P. 50120, Toluca, Estado de México, México (Mexico); Ornelas-Gutierrez, Carlos; Antunez, Wilber [Centro de investigación en Materiales Avanzados S. C. (CIMAV). Miguel de Cervantes N° 120. C.P. 31109. Chihuahua, Chihuahua, México (Mexico)

    2015-06-15

    Metallic Zn nanodisks with hexagonal morphology were obtained onto glass substrate under vacuum thermal evaporation. A thermal characterization of Zn nanodiks showed a lower oxidation temperature than source powder Zn. Different thermal treatment on Zn nanodisks played an important role on the morphology, crystal size and surface vibrational modes of ZnO. The growth of ZnO nanoneedles started at the edge of metallic zinc hexagonal structures according with SEM images, the higher temperature the longer needles were grown. XRD diffractogram confirmed the wurtzite structure of ZnO with metallic nuclei. A wide band between 530 and 580 cm{sup −1} of Raman scattering corresponded at surface vibrational modes not observed at higher temperature.

  8. Time-dependent thermal effects in GRB afterglows

    Energy Technology Data Exchange (ETDEWEB)

    Postnov, K.A.; Blinnikov, S.I.; Kosenko, D.I.; Sorokina, E.I

    2004-06-01

    Time-dependent thermal effects should accompany standard non-thermal afterglows of GRB when {gamma}-rays pass through inhomogeneous surroundings of the GRB site. Thermal relaxation of an optically thin plasma is calculated using time-dependent collisional ionization of the plasma ion species. X-ray emission lines are similar to those found in the fading X-ray afterglow of GRB 011211. Thermal relaxation of clouds or shells around the GRB site could also contribute to the varying late optical GRB afterglows, such as in GRB 021004 and GRB 030329.

  9. Pulsed pump: Thermal effects in solid state lasers under super ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 67; Issue 6. Pulsed ... Pulse pump; thermal effects; thermal lensing; phase shift; diode-pumped solid state laser; super-Gaussian pump profile. Abstract. Solid state laser (SSL) powers can be realistically scaled when pumped by a real, efficient and multimode pulse.

  10. Effect of normal processes on thermal conductivity of germanium ...

    Indian Academy of Sciences (India)

    The effect of normal scattering processes is considered to redistribute the phonon momentum in (a) the same phonon branch – KK-S model and (b) between different phonon branches – KK-H model. Simplified thermal conductivity relations are used to estimate the thermal conductivity of germanium, silicon and diamond ...

  11. Effect of normal processes on thermal conductivity of germanium ...

    Indian Academy of Sciences (India)

    Abstract. The effect of normal scattering processes is considered to redistribute the phonon momentum in (a) the same phonon branch – KK-S model and (b) between differ- ent phonon branches – KK-H model. Simplified thermal conductivity relations are used to estimate the thermal conductivity of germanium, silicon and ...

  12. Effect of urbanization on the thermal structure in the atmosphere

    Science.gov (United States)

    R. Viskanta; R. O. Johnson; R. W., Jr. Bergstrom

    1977-01-01

    An unsteady two-dimensional transport model was used to study the short-term effects of urbanization and air pollution on the thermal structure in the urban atmosphere. A number of simulations for summer conditions representing the city of St. Louis were performed. The diurnal variation of the surface temperature and thermal structure are presented and the influences...

  13. Thermal dose requirement for tissue effect: experimental and clinical findings

    Science.gov (United States)

    Dewhirst, Mark; Viglianti, Benjamin L.; Lora-Michiels, Michael; Hoopes, P. Jack; Hanson, Margaret A.

    2003-06-01

    In this review we have summarized the basic principles that govern the relationships between thermal exposure (temperature and time of exposure) and thermal damage, with an emphasis on normal tissue effects. We have also attempted to identify specific thermal dose information (for safety and injury) for a variety of tissues in a variety of species. We address the use, accuracy and difficulty of conversion of an individual time and temperature (thermal dose) to a standardized value (eg equivalent minutes at 43degC) for comparison of thermal treatments. Although, the conversion algorithm appears to work well within a range of moderately elevated temperatures (2-15degC) above normal physiologic baseline (37-39degC) there is concern that conversion accuracy does not hold up for temperatures which are minimally or significantly above baseline. An extensive review of the literature suggests a comprehensive assessment of the "thermal dose-to-tissue effect" has not previously been assembled for most individual tissues and never been viewed in a semi-comprehensive (tissues and species) manner. Finally, we have addressed the relationship of thermal dose-to-effect vs. baseline temperature. This issues is important since much of the thermal dose-to-effect information has been accrued in animal models with baseline temperatures 1-2 deg higher than that of humans.

  14. Convection with local thermal non-equilibrium and microfluidic effects

    CERN Document Server

    Straughan, Brian

    2015-01-01

    This book is one of the first devoted to an account of theories of thermal convection which involve local thermal non-equilibrium effects, including a concentration on microfluidic effects. The text introduces convection with local thermal non-equilibrium effects in extraordinary detail, making it easy for readers newer to the subject area to understand. This book is unique in the fact that it addresses a large number of convection theories and provides many new results which are not available elsewhere. This book will be useful to researchers from engineering, fluid mechanics, and applied mathematics, particularly those interested in microfluidics and porous media.

  15. Thermal Arrest Memory Effect in Ni-Mn-Ga Alloys

    Directory of Open Access Journals (Sweden)

    A. Rudajevova

    2008-01-01

    Full Text Available Dilatation characteristics were measured to investigate the thermal arrest memory effect in Ni53.6Mn27.1Ga19.3 and Ni54.2Mn29.4Ga16.4 alloys. Interruption of the martensite-austenite phase transformation is connected with the reduction of the sample length after thermal cycle. If a total phase transformation took place in the complete thermal cycle following the interruption, then the sample length would return to its original length. Analysis of these results has shown that the thermal arrest memory effect is a consequence of a stress-focusing effect and shape memory effect. The stress-focusing effect occurs when the phase transformation propagates radially in a cylindrical sample from the surface, inward to the center. Evolution and release of the thermoelastic deformations in both alloys during heating and cooling are analyzed.

  16. Thermal Mass & Dynamic Effects Danish Building Regulation

    DEFF Research Database (Denmark)

    Le Dreau, Jerome; Selman, Ayser Dawod; Heiselberg, Per

    will focus on three main aspects: ♦ Assess the robustness of the monthly calculation method by varying the input parameters (Part 3) ♦ Better take into consideration the thermal mass in the actual tool by updating the utilisation factors used for the calculation of cooling and heating (Part 3) ♦ Find...... a method to evaluate night-time ventilation in the monthly calculation (Part 4)...

  17. Modeling thermal effects in braking systems of railway vehicles

    Directory of Open Access Journals (Sweden)

    Milošević Miloš S.

    2012-01-01

    Full Text Available The modeling of thermal effects has become increasingly important in product design in different transport means, road vehicles, airplanes, railway vehicles, and so forth. The thermal analysis is a very important stage in the study of braking systems, especially of railway vehicles, where it is necessary to brake huge masses, because the thermal load of a braked railway wheel prevails compared to other types of loads. In the braking phase, kinetic energy transforms into thermal energy resulting in intense heating and high temperature states of railway wheels. Thus induced thermal loads determine thermomechanical behavior of the structure of railway wheels. In cases of thermal overloads, which mainly occur as a result of long-term braking on down-grade railroads, the generation of stresses and deformations occurs, whose consequences are the appearance of cracks on the rim of a wheel and the final total wheel defect. The importance to precisely determine the temperature distribution caused by the transfer process of the heat generated during braking due to the friction on contact surfaces of the braking system makes it a challenging research task. Therefore, the thermal analysis of a block-braked solid railway wheel of a 444 class locomotive of the national railway operator Serbian Railways is processed in detail in this paper, using analytical and numerical modeling of thermal effects during long-term braking for maintaining a constant speed on a down-grade railroad.

  18. Effects of thermal insulation on electrical connections and outlet boxes

    Science.gov (United States)

    Beausoliel, R. W.; Clifton, J. R.; Meese, W. J.

    1981-04-01

    When residential walls are retrofitted with foamed-in urea formaldehyde or blown-in cellulose thermal insulations, the insulation may enter electrical outlet and switch boxes. The effects of these thermal insulations on the durability of electrical components were studied. These studies were carried out at 44, 75, and 96 percent relative humidities with test periods between one and twelve months. Laboratory test methods were developed and tests performed to determine the electrical and corrosive effects of urea formaldehyde and cellulose thermal insulation contained in electrical outlet and switch boxes.

  19. Effect of thermal fluctuations on a charged dilatonic black Saturn

    Directory of Open Access Journals (Sweden)

    Behnam Pourhassan

    2016-04-01

    Full Text Available In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.

  20. Effect of thermal fluctuations on a charged dilatonic black Saturn

    Energy Technology Data Exchange (ETDEWEB)

    Pourhassan, Behnam, E-mail: b.pourhassan@du.ac.ir [School of Physics, Damghan University, Damghan (Iran, Islamic Republic of); Faizal, Mir, E-mail: f2mir@uwaterloo.ca [Department of Physics and Astronomy, University of Lethbridge, Lethbridge, AB T1K 3M4 (Canada)

    2016-04-10

    In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.

  1. Effect of Thermal Fluctuations on a Charged Dilatonic Black Saturn

    CERN Document Server

    Pourhassan, Behnam

    2016-01-01

    In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.

  2. Thermal /Soret/ diffusion effects on interfacial mass transport rates

    Science.gov (United States)

    Rosner, D. E.

    1980-01-01

    It is shown that thermal (Soret) diffusion significantly alters convective mass transport rates and important transition temperatures in highly nonisothermal flow systems involving the transport of 'heavy' species (vapors or particles). Introduction of the Soret transport term is shown to result in mass transfer effects similar to those of 'suction' and a homogeneous chemical 'sink'. It is pointed out that this analogy provides a simple method of correlating and predicting thermal diffusion effects in the abovementioned systems.

  3. EFFECTS OF SURFACE MORPHOLOGY ON THERMAL CONTACT RESISTANCE

    Directory of Open Access Journals (Sweden)

    Haiming Huang

    2011-01-01

    Full Text Available The thermal contact resistance is common in aerospace industry, nuclear reactors and electronic equipments. The work addresses a new scheme for determining the thermal contact resistance between a smooth surface of a film and a rough surface of a metal specimen. The finite element method was used as a tool to explore the surface morphology effect on the thermal contact resistance while the temperature of the contact surface was determined by a regression method. According to the results developed, the temperature on the contact surfaces linearly drops with the increasing average height of surface roughness and nonlinearly drops with the increasing ratio between non-contact area and nominal contact area. On the other hand, the thermal contact resistance increases linearly with increases in the average height of the surface roughness. What's more, the thermal contact resistance increases in a non-linear manner as the ratio of the non-contact area to the nominal contact area is increasing.

  4. Dynamic nonlinear thermal optical effects in coupled ring resonators

    Directory of Open Access Journals (Sweden)

    Chenguang Huang

    2012-09-01

    Full Text Available We investigate the dynamic nonlinear thermal optical effects in a photonic system of two coupled ring resonators. A bus waveguide is used to couple light in and out of one of the coupled resonators. Based on the coupling from the bus to the resonator, the coupling between the resonators and the intrinsic loss of each individual resonator, the system transmission spectrum can be classified by three different categories: coupled-resonator-induced absorption, coupled-resonator-induced transparency and over coupled resonance splitting. Dynamic thermal optical effects due to linear absorption have been analyzed for each category as a function of the input power. The heat power in each resonator determines the thermal dynamics in this coupled resonator system. Multiple “shark fins” and power competition between resonators can be foreseen. Also, the nonlinear absorption induced thermal effects have been discussed.

  5. Effect of interfacial treatment on the thermal properties of thermal conductive plastics

    Directory of Open Access Journals (Sweden)

    2007-09-01

    Full Text Available In this paper, ZnO, which is processed by different surface treatment approaches, is blended together with polypropylene to produce thermal conductive polymer composites. The composites are analyzed by Fourier transform infrared (FTIR spectroscopy and scanning electron microscopy (SEM to investigate the surface modification of filler, their distribution in the matrix and the condition of two-phase interface. Optimized content of filler surface modifier is investigated as well. The results showed that using low-molecular coupling agent produces positive effect to improve the interface adhesion between filler and matrix, and the thermal conductivity of the composite as well. Macro-molecular coupling agent can strongly improve two-phase interface, but it is not beneficial at obtaining a high thermal conductivity. The blend of ZnO without modification and polypropylene has many defects in the two-phase interface, and the thermal conductivity of the composite is between those of composites produced by previous two approaches. The surface treatment of the filler also allowed producing the composites with lower coefficient of thermal expansion (CTE. As for the content of low-molecular coupling agent, it obtains the best effect at 1.5 wt%.

  6. Atomic-scale friction : thermal effects and capillary condensation

    NARCIS (Netherlands)

    Jinesh, Kochupurackal Balakrishna Pillai

    2006-01-01

    This work entitled as "Atomic-scale friction: thermal effects and capillary condensation" is a study on the fundamental aspects of the origin of friction from the atomic-scale. We study two realistic aspects of atomic-scale friction, namely the effect of temperature and the effect of relative

  7. Analysis of Thermal Radiation Effects on Temperatures in Turbine Engine Thermal Barrier Coatings

    Science.gov (United States)

    Siegel, Robert; Spuckler, Charles M.

    1998-01-01

    Thermal barrier coatings are important, and in some instances a necessity, for high temperature applications such as combustor liners, and turbine vanes and rotating blades for current and advanced turbine engines. Some of the insulating materials used for coatings, such as zirconia that currently has widespread use, are partially transparent to thermal radiation. A translucent coating permits energy to be transported internally by radiation, thereby increasing the total energy transfer and acting like an increase in thermal conductivity. This degrades the insulating ability of the coating. Because of the strong dependence of radiant emission on temperature, internal radiative transfer effects are increased as temperatures are raised. Hence evaluating the significance of internal radiation is of importance as temperatures are increased to obtain higher efficiencies in advanced engines.

  8. Effective Thermal Conductivity of Insulating Material made from Recycled Newspapers

    Science.gov (United States)

    Yamada, Etsuro; Takahashi, Kaneko; Sato, Mitsuo; Ishii, Yukihiro

    In this paper, the experimental results are represented on the effective thermal conductivity of cellulose insulation powder which is made from recycled newspapers. This insulating material is useful for energy and resources saving. The steady state cylindrical absolute method is employed by considering the accuracy of measurement. The experimental results are compared with the ones measured previously by other methods. The main results obtained are as follows (1) The effective thermal conductivity of this insulating material increases with increasing temperature and effective specific density, respectively. But, these increasing rate is not so large. (2) The effective thermal conductivity is about 0.04-0.06[W/mK] at the range of the effective specific density less than 100 [kg/m3]. This value is comparable with other industrial insulating materials.

  9. Effects of non-thermal plasma on mammalian cells.

    Directory of Open Access Journals (Sweden)

    Sameer Kalghatgi

    2011-01-01

    Full Text Available Thermal plasmas and lasers have been widely used in medicine to cut, ablate and cauterize tissues through heating; in contrast, non-thermal plasma produces no heat, so its effects can be selective. In order to exploit the potential for clinical applications, including wound healing, sterilization, blood coagulation, and cancer treatment, a mechanistic understanding of the interaction of non-thermal plasma with living tissues is required. Using mammalian cells in culture, it is shown here that non-thermal plasma created by dielectric barrier discharge (DBD has dose-dependent effects that range from increasing cell proliferation to inducing apoptosis. It is also shown that these effects are primarily due to formation of intracellular reactive oxygen species (ROS. We have utilized γ-H2AX to detect DNA damage induced by non-thermal plasma and found that it is initiated by production of active neutral species that most likely induce formation of organic peroxides in cell medium. Phosphorylation of H2AX following non-thermal plasma treatment is ATR dependent and ATM independent, suggesting that plasma treatment may lead to replication arrest or formation of single-stranded DNA breaks; however, plasma does not lead to formation of bulky adducts/thymine dimers.

  10. Effects of Building Design Elements on Residential Thermal Environment

    Directory of Open Access Journals (Sweden)

    Yingbao Yang

    2017-12-01

    Full Text Available Residential thermal environment affects the life of residents in terms of their physical and mental health. Many studies have shown that building design elements affect the urban thermal environment. In this study, Nanjing City was used as the study area. A three-dimensional microclimate model was used to simulate and analyze the effects of four main factors, namely, building height, density, layout and green ratio, on thermal environment in residential areas. Results showed that 25% building density obtained a low average air temperature (ATa and average predicted mean vote (APMV during 24 h. Thus, a higher building height indicates a lower ATa and APMV and better outdoor comfort level. In addition, peripheral layout had the lowest ATa and APMV, followed by the determinant and point group layouts. The green ratio increased from 0% to 50% with a 10% step and the ATa and APMV decreased gradually. However, when the green ratio increased from 30% to 40%, ATa and APMV decreased most. The effects of building height, density and green ratio on the thermal environment in residential areas were interactive. The effects of building density, green ratio and layout on hourly air temperature and hourly predicted mean vote in daytime varied from these indicators during night time. How the four building design elements interact with thermal environment were probed from two aspects of air temperature and thermal comfort based on the validated ENVI-met, which is the element of novelty in this study. However, thermal comfort has rarely been considered in the past studies about urban outdoor thermal environment.

  11. Thermal Hydraulic Integral Effect Tests for Pressurized Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Baek, W. P.; Song, C. H.; Kim, Y. S. and others

    2005-02-15

    The objectives of the project are to construct a thermal-hydraulic integral effect test facility and to perform various integral effect tests for design, operation, and safety regulation of pressurized water reactors. During the first phase of this project (1997.8{approx}2002.3), the basic technology for thermal-hydraulic integral effect tests was established and the basic design of the test facility was accomplished: a full-height, 1/300-volume-scaled full pressure facility for APR1400, an evolutionary pressurized water reactor that was developed by Korean industry. Main objectives of the present phase (2002.4{approx}2005.2), was to optimize the facility design and to construct the experimental facility. We have performed following researches: 1) Optimization of the basic design of the thermal-hydraulic integral effect test facility for PWRs - ATLAS (Advanced Thermal-hydraulic Test Loop for Accident Simulation) - Reduced height design for APR1400 (+ specific design features of KSNP safety injection systems) - Thermal-hydraulic scaling based on three-level scaling methodology by Ishii et al. 2) Construction of the ATLAS facility - Detailed design of the test facility - Manufacturing and procurement of components - Installation of the facility 3) Development of supporting technology for integral effect tests - Development and application of advanced instrumentation technology - Preliminary analysis of test scenarios - Development of experimental procedures - Establishment and implementation of QA system/procedure.

  12. Analysis and Experimental on Aircraft Insulation Thermal Bridge Effect

    Directory of Open Access Journals (Sweden)

    XIA Tian

    2017-06-01

    Full Text Available Two kinds of typical aircraft insulation structures were designed for the heat bridge in the metal ribs of aircraft insulation structures. In order to study the influence of heat bridge effect on thermal insulation performance, each configuration was analyzed by the transient heat transfer FEA, check point temperature was obtained in the hot surface temperature of 100 ℃, 200 ℃, 300 ℃, 424 ℃ respectively, and the validity of FEA was proved by insulation performance experiment. The result showed that the thermal bridge has a great influence to the insulation performance of insulation structure, and the thermal bridge influence should be considered adequately when the insulation structure designed. Additionally, the blocking method for thermal bridge is also put forward.

  13. Photon-induced thermal effects in superconducting coplanar waveguide resonators

    Science.gov (United States)

    Wang, Yiwen; Zhou, Pinjia; Wei, Lianfu; Li, Haijie; Zhang, Beihong; Zhang, Miao; Wei, Qiang; Fang, Yurong; Cao, Chunhai

    2013-10-01

    We experimentally investigated the optical responses of a superconducting niobium resonator. It was found that, with increasing radiation power, the resonance frequency increases monotonically below around 500 mK, decreases monotonically above around 1 K, and exhibits a nonmonotonic behavior at around 700 mK. These observations show that one can operate the irradiated resonator in three temperature regimes, depending on whether two-level system (TLS) effects or kinetic inductance effects dominate. Furthermore, we found that the optical responses at ultra-low temperatures can be qualitatively regarded as a photon-induced thermalization effect of TLSs, which could be utilized to achieve thermal sensitive photon detections.

  14. Theoretical investigation of some thermal effects in turbulence modeling

    Energy Technology Data Exchange (ETDEWEB)

    Mathelin, Lionel [LIMSI-CNRS, Orsay (France); Bataille, Francoise [PROMES-CNRS, Perpignan (France); Ye, Zhou [Lawrence Livermore National Lab., Livermore, CA (United States)

    2008-11-15

    Fluid compressibility effects arising from thermal rather than dynamical aspects are theoretically investigated in the framework of turbulent flows. The Mach number is considered low and not to induce significant compressibility effects which here occur due to a very high thermal gradient within the flowfield. With the use of the Two-Scale Direct Interaction Approximation approach, essential turbulent correlations are derived in a one-point one-time framework. In the low velocity gradient limit, they are shown to directly depend on the temperature gradient, assumed large. The impact of thermal effects onto the transport equations of the turbulent kinetic energy and dissipation rate is also investigated, together with the transport equation for both the density and the internal energy variance.

  15. Thermal infrared images to quantify thermal ablation effects of acid and base on target tissues

    Directory of Open Access Journals (Sweden)

    Ran Liu

    2015-07-01

    Full Text Available Hyperthermia (42-46°C, treatment of tumor tissue through elevated temperature, offers several advantages including high cost-effectiveness, highly targeted ablation and fewer side effects and hence higher safety level over traditional therapies such as chemotherapy and radiotherapy. Recently, hyperthermia using heat release through exothermic acid-base neutralization comes into view owing to its relatively safe products of salt and water and highly confined ablation. However, lack of quantitative understanding of the spatial and temporal temperature profiles that are produced by simultaneous diffusion of liquid chemical and its chemical reaction within tumor tissue impedes the application of this method. This article is dedicated to quantify thermal ablation effects of acid and base both individually and as in neutralization via infrared captured thermal images. A theoretical model is used to approximate specific heat absorption rate (SAR based on experimental measurements that contrast two types of tissue, normal pork and pig liver. According to the computation, both pork and liver tissue has a higher ability in absorbing hydrochloric acid (HCl than sodium hydroxide, hence suggesting that a reduced dosage for HCl is appropriate in a surgery. The heating effect depends heavily on the properties of tissue types and amount of chemical reagents administered. Given thermal parameters such as SAR for different tissues, a computational model can be made in predicting temperature transitions which will be helpful in planning and optimizing surgical hyperthermia procedures.

  16. Thermal infrared images to quantify thermal ablation effects of acid and base on target tissues

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ran, E-mail: jliubme@tsinghua.edu.cn, E-mail: liuran@tsinghua.edu.cn; Liu, Jing, E-mail: jliubme@tsinghua.edu.cn, E-mail: liuran@tsinghua.edu.cn [Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing 100084 (China); Wang, Jia [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States)

    2015-07-15

    Hyperthermia (42-46°C), treatment of tumor tissue through elevated temperature, offers several advantages including high cost-effectiveness, highly targeted ablation and fewer side effects and hence higher safety level over traditional therapies such as chemotherapy and radiotherapy. Recently, hyperthermia using heat release through exothermic acid-base neutralization comes into view owing to its relatively safe products of salt and water and highly confined ablation. However, lack of quantitative understanding of the spatial and temporal temperature profiles that are produced by simultaneous diffusion of liquid chemical and its chemical reaction within tumor tissue impedes the application of this method. This article is dedicated to quantify thermal ablation effects of acid and base both individually and as in neutralization via infrared captured thermal images. A theoretical model is used to approximate specific heat absorption rate (SAR) based on experimental measurements that contrast two types of tissue, normal pork and pig liver. According to the computation, both pork and liver tissue has a higher ability in absorbing hydrochloric acid (HCl) than sodium hydroxide, hence suggesting that a reduced dosage for HCl is appropriate in a surgery. The heating effect depends heavily on the properties of tissue types and amount of chemical reagents administered. Given thermal parameters such as SAR for different tissues, a computational model can be made in predicting temperature transitions which will be helpful in planning and optimizing surgical hyperthermia procedures.

  17. Thermal infrared images to quantify thermal ablation effects of acid and base on target tissues

    Science.gov (United States)

    Liu, Ran; Wang, Jia; Liu, Jing

    2015-07-01

    Hyperthermia (42-46°C), treatment of tumor tissue through elevated temperature, offers several advantages including high cost-effectiveness, highly targeted ablation and fewer side effects and hence higher safety level over traditional therapies such as chemotherapy and radiotherapy. Recently, hyperthermia using heat release through exothermic acid-base neutralization comes into view owing to its relatively safe products of salt and water and highly confined ablation. However, lack of quantitative understanding of the spatial and temporal temperature profiles that are produced by simultaneous diffusion of liquid chemical and its chemical reaction within tumor tissue impedes the application of this method. This article is dedicated to quantify thermal ablation effects of acid and base both individually and as in neutralization via infrared captured thermal images. A theoretical model is used to approximate specific heat absorption rate (SAR) based on experimental measurements that contrast two types of tissue, normal pork and pig liver. According to the computation, both pork and liver tissue has a higher ability in absorbing hydrochloric acid (HCl) than sodium hydroxide, hence suggesting that a reduced dosage for HCl is appropriate in a surgery. The heating effect depends heavily on the properties of tissue types and amount of chemical reagents administered. Given thermal parameters such as SAR for different tissues, a computational model can be made in predicting temperature transitions which will be helpful in planning and optimizing surgical hyperthermia procedures.

  18. FY 2017 – Thermal Aging Effects on Advanced Structural Materials

    Energy Technology Data Exchange (ETDEWEB)

    Li, Meimei [Argonne National Lab. (ANL), Argonne, IL (United States); Natesan, K [Argonne National Lab. (ANL), Argonne, IL (United States); Chen, Wei-Ying [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-08-01

    This report provides an update on the evaluation of the effect of thermal aging on tensile properties of existing laboratory-sized heats of Alloy 709 austenitic stainless steel and the completion of effort on the thermal aging effect on the tensile properties of optimized G92 ferritic-martensitic steel. The report is a Level 3 deliverable in FY17 (M3AT-17AN1602081), under the Work Package AT-17AN160208, “Advanced Alloy Testing - ANL” performed by the Argonne National Laboratory (ANL), as part of the Advanced Reactor Technologies Program.

  19. Evidence of Space-Charge Effects in Thermal Poling

    DEFF Research Database (Denmark)

    Wu, X.; Arentoft, Jesper; Wong, D.

    1999-01-01

    The in situ thermal poling processes in germanosilicate fibers for positive and negative poling voltages are significantly different. Thermal poling of silica fibers consists of two processes: the faster linear process of charge migration and the subsequent single exponential process of charge...... ionization. Both the shielding electrical field due to charge migration and the ionization electrical field due to charge ionization are able to be frozen-in at room temperature acid lead to the residual linear electrooptic effects, The observations support that the mechanism of the induced electrooptic...... effects is based on space charge electrical fields instead of dipole/bond orientation....

  20. Nonreciprocal light transmission based on the thermal radiative effect

    DEFF Research Database (Denmark)

    Liu, Li; Dong, Jianji; Ding, Yunhong

    2015-01-01

    Nonreciprocal light transmission is critical in building optical isolations and circulations in optical communication systems. Achieving high optical isolation and broad bandwidth with CMOS-compatibility are still difficult in silicon nano-photonics. Here we first experimentally demonstrate...... to the significant characteristics of the thermal radiative effect, which could cause a fiber displacement up to tens of microns. This powerful thermal radiative effect opens up a new opportunity for nonreciprocal light transmission which is promising to be used in complete on-chip nonreciprocal devices...

  1. Determination of BWR Spent Nuclear Fuel Assembly Effective Thermal Conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Matthew D. Hinds

    2001-10-17

    The purpose of this calculation is to provide an effective thermal conductivity for use in predicting peak cladding temperatures in boiling water reactor (BWR) fuel assemblies with 7x7,8x8, and 9x9 rod arrays. The first objective of this calculation is to describe the development and application of a finite element representation that predicts peak spent nuclear fuel temperatures for BWR assemblies. The second objective is to use the discrete representation to develop a basis for determining an effective thermal conductivity (described later) for a BWR assembly with srneared/homogeneous properties and to investigate the thermal behavior of a spent fuel assembly. The scope of this calculation is limited to a steady-state two-dimensional representation of the waste package interior region. This calculation is subject to procedure AP-3.124, Calculations (Ref. 27) and guided by the applicable technical work plan (Ref. 14). While these evaluations were originally developed for the thermal analysis of conceptual waste package designs emplaced in the potential repository at Yucca Mountain, the methodology applies to storage and transportation thermal analyses as well. Note that the waste package sketch in Attachment V depicts a preliminary design, and should not be interpreted otherwise.

  2. A review on ergonomics of headgear: Thermal effects

    NARCIS (Netherlands)

    Bogerd, C.P.; Aerts, J.M.; Annaheim, S.; Bröde, P.; Bruyne, G. de; Flouris, A.D.; Kuklane, K.; Sotto Mayor, T.; Rossi, R.M.

    2015-01-01

    The thermal effects related to wearing headgear are complex and different studies have investigated single parts of this topic. This review aims at summarizing the different findings to give a complete overview on this topic as well as to suggest new perspectives. Headgear increases head insulation

  3. Thermal effects on parallel resonance energy of whistler mode wave

    Indian Academy of Sciences (India)

    Abstract. In this short communication, we have evaluated the effect of thermal velocity of the plasma particles on the energy of resonantly interacting energetic electrons with the propagating whistler mode waves as a function of wave frequency and L-value for the normal and disturbed magnetospheric conditions. During the ...

  4. Effective action for hard thermal loops in gravitational fields

    Directory of Open Access Journals (Sweden)

    R.R. Francisco

    2016-05-01

    Full Text Available We examine, through a Boltzmann equation approach, the generating action of hard thermal loops in the background of gravitational fields. Using the gauge and Weyl invariance of the theory at high temperature, we derive an explicit closed-form expression for the effective action.

  5. Effect of high thermal expansion glass infiltration on mechanical ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. This work studies the effect on the mechanical properties of alumina-10 wt% zirconia (3 mol% yttria stabilized) composite by infiltrating glass of a higher thermal expansion (soda lime glass) on the surface at high temperature. The glass improved the strength of composite at room temperature as well as at high.

  6. Differential effects of thermal and chemical stressors on tissue balls ...

    African Journals Online (AJOL)

    Coral cell aggregates (tissue balls) from four species (Acropora muricata, Fungia repanda, Pavona cactus and Pocillopora damicornis) were used as an indicator to investigate the effects on the corals of thermal stress and of chemical extracts from three sponges (Adocia sp., Haliclona sp. and Lissodendoryx sp.) and one ...

  7. Effect of high heating rate on thermal decomposition behaviour of ...

    Indian Academy of Sciences (India)

    but rely on the concentration of hydrogen. The model ... first-order rate law. Lehmhus and Rausch (2004) have annealed TiH2 pow- der in air and argon. In argon, the powder does not develop a surface layer and as a result, a small amount of hydro- gen is lost ... rate effect on the thermal decomposition behaviour of TiH2.

  8. Analytical model of transient thermal effect on convectional cooled ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 81; Issue 4. Analytical model of transient thermal effect on convectional cooled end-pumped laser rod ... The transient analytical solutions of temperature distribution, stress, strain and optical path difference in convectional cooled end-pumped laser rod are derived.

  9. Infrared lens thermal effect: equivalent focal shift and calculating model

    Science.gov (United States)

    Zhang, Cheng-shuo; Shi, Zelin; Feng, Bin; Xu, Bao-shu

    2014-11-01

    It's well-know that the focal shift of infrared lens is the major factor in degeneration of imaging quality when temperature change. In order to figure out the connection between temperature change and focal shift, partial differential equations of thermal effect on light path are obtained by raytrace method, to begin with. The approximately solution of the PDEs show that focal shift is proportional to temperature change. And a formula to compute the proportional factor is given. In order to understand infrared lens thermal effect deeply, we use defocus by image plane shift at constant temperature to equivalently represent thermal effect on infrared lens. So equivalent focal shift (EFS) is defined and its calculating model is proposed at last. In order to verify EFS and its calculating model, Physical experimental platform including a motorized linear stage with built-in controller, blackbody, target, collimator, IR detector, computer and other devices is developed. The experimental results indicate that EFS make the image plane shift at constant temperature have the same influence on infrared lens as thermal effect and its calculating model is correct.

  10. On the effect of temperature dependent thermal conductivity on ...

    African Journals Online (AJOL)

    We consider the effect of temperature dependent thermal conductivity on temperature rise in biologic tissues during microwave heating. The method of asymptotic expansion is used for finding solution. An appropriate matching procedure was used in our method. Our result reveals the possibility of multiple solutions and it ...

  11. The effect of Acacia karroo supplementation and thermal ...

    African Journals Online (AJOL)

    The objective of the current study was to determine the effect of Acacia karroo supplementation and thermal preparation on consumer sensory scores of meat from indigenous Xhosa lop-eared goat breed. 18 castrated four-month-old Xhosa lop-eared kids were kept at the University of Fort Hare Farm until slaughter. Sample ...

  12. Thermal-vacuum effects on polymer matrix composite materials

    Science.gov (United States)

    Tennyson, R. C.; Mabson, G. E.

    1991-01-01

    Results are presented on the thermal-vacuum response of a variety of fiber reinforced polymers matrix composites that comprised the UTIAS experiment on the LDEF satellite. Theoretical temperature-time predictions for this experiment are in excellent agreement with test data. Results also show quite clearly the effect of outgassing in the dimensional changes of these materials and the corresponding coefficients of thermal expansion. Finally, comparison with ground-based simulation tests are presented as well. Use of these data for design purposes are also given.

  13. Concrete containment analysis including thermal effects

    Energy Technology Data Exchange (ETDEWEB)

    Pfeiffer, P.A.; Kennedy, J.M.; Marchertas, A.H.

    1989-01-01

    Pretest predictions were made by the staff of the Engineering Mechanics Program at ANL for the response of the 1:6-scale reinforced concrete containment model that was tested to failure by liner tearing and leakage at the Sandia National Laboratories. Questions have been raised in regard to possible effects of temperature in combination with internal pressure on the behavior of the model. Specifically, if the containment had been subjected to elevated temperature as well as internal pressure, what differences in pressure capacity, failure mechanism and location would have been predicted when compared to the analysis of internal pressure alone. The purpose of this paper is to address these questions. 3 refs., 9 figs.

  14. Evaluating the thermal reduction effect of plant layers on rooftops

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Chih-Fang [Department of Landscape Design and Management, National Chin-Yi University of Technology, No. 35, Lane 215, Sec. 1, Jhongshan Road, Taiping City, Taichung County 411 (China)

    2008-07-01

    This study examines the thermal reduction effect of plant layers on rooftops through experiments performed in a controlled environment. The relevant parameters are coverage ratio (CR) and total leaf thickness (TLT). Both parameters are positively correlated with thermal reduction ratio (TRR). The TRR data of all experiments were plotted on a grid system with CR on the x-axis and TLT on the y-axis. A TRR map was then drawn using the curve fitting process. The applicability of the TRR map drawn for Codiaeum variegatum (1) was further confirmed by performing experiments with Cordyline terminalis (1) and Ixora duffii (1) and by results of experiments on C. variegatum (2), C. terminalis (2), Duranta repens, and I. duffii (2) in outdoor environments. The TRR map provides quantitative and straightforward guidance on thermal reduction planting arrangements for green roofs. (author)

  15. Aging effects on vertical graphene nanosheets and their thermal stability

    Science.gov (United States)

    Ghosh, S.; Polaki, S. R.; Ajikumar, P. K.; Krishna, N. G.; Kamruddin, M.

    2017-10-01

    The present study investigates environmental aging effects and thermal stability of vertical graphene nanosheets (VGN). Self-organized VGN is synthesized by plasma enhanced chemical vapor deposition and exposed to ambient conditions over 6-month period to examine its aging behavior. A systematic inspection is carried out on morphology, chemical structure, wettability and electrical property by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, water contact angle and four-probe resistivity measurements at regular intervals, respectively. Detailed microscopic and spectroscopic analysis substantiated the retention of graphitic quality and surface chemistry of VGN over the test period. An unchanged sheet resistance and hydrophobicity reveals its electrical and wetting stability over the time, respectively. Thermogravimetric analysis ensures an excellent thermal stability of VGN up to 575 °C in ambient atmosphere. These findings of long-term morphological, structural, wetting, electrical and thermal stability of VGN validate their potential utilization for the next-generation device applications.

  16. Thermal properties of soils: effect of biochar application

    Science.gov (United States)

    Usowicz, Boguslaw; Lukowski, Mateusz; Lipiec, Jerzy

    2014-05-01

    Thermal properties (thermal conductivity, heat capacity and thermal diffusivity) have a significant effect on the soil surface energy partitioning and resulting in the temperature distribution. Thermal properties of soil depend on water content, bulk density and organic matter content. An important source of organic matter is biochar. Biochar as a material is defined as: "charcoal for application as a soil conditioner". Biochar is generally associated with co-produced end products of pyrolysis. Many different materials are used as biomass feedstock for biochar, including wood, crop residues and manures. Additional predictions were done for terra preta soil (also known as "Amazonian dark earth"), high in charcoal content, due to adding a mixture of charcoal, bone, and manure for thousands of years i.e. approximately 10-1,000 times longer than residence times of most soil organic matter. The effect of biochar obtained from the wood biomass and other organic amendments (peat, compost) on soil thermal properties is presented in this paper. The results were compared with wetland soils of different organic matter content. The measurements of the thermal properties at various water contents were performed after incubation, under laboratory conditions using KD2Pro, Decagon Devices. The measured data were compared with predictions made using Usowicz statistical-physical model (Usowicz et al., 2006) for biochar, mineral soil and soil with addition of biochar at various water contents and bulk densities. The model operates statistically by probability of occurrence of contacts between particular fractional compounds. It combines physical properties, specific to particular compounds, into one apparent conductance specific to the mixture. The results revealed that addition of the biochar and other organic amendments into the soil caused considerable reduction of the thermal conductivity and diffusivity. The mineral soil showed the highest thermal conductivity and diffusivity

  17. Prediction of the Effective Thermal Conductivity of Powder Insulation

    Science.gov (United States)

    Jin, Lingxue; Park, Jiho; Lee, Cheonkyu; Jeong, Sangkwon

    The powder insulation method is widely used in structural and cryogenic systems such as transportation and storage tanks of cryogenic fluids. The powder insulation layer is constructed by small particle powder with light weight and some residual gas with high porosity. So far, many experiments have been carried out to test the thermal performance of various kinds of powder, including expanded perlite, glass microspheres, expanded polystyrene (EPS). However, it is still difficult to predict the thermal performance of powder insulation by calculation due to the complicated geometries, including various particle shapes, wide powder diameter distribution, and various pore sizes. In this paper, the effective thermal conductivity of powder insulation has been predicted based on an effective thermal conductivity calculationmodel of porous packed beds. The calculation methodology was applied to the insulation system with expanded perlite, glass microspheres and EPS beads at cryogenic temperature and various vacuum pressures. The calculation results were compared with previous experimental data. Moreover, additional tests were carried out at cryogenic temperature in this research. The fitting equations of the deformation factor of the area-contact model are presented for various powders. The calculation results show agood agreement with the experimental results.

  18. Effective Thermal Expansion Property of Consolidated Granular Materials.

    Science.gov (United States)

    Küçük, Gülşad; Gonzalez, Marcial; Cuitiño, Alberto M

    2017-11-09

    Thermally-assisted compaction of granular materials is of keen interest in many engineering applications. A proper estimation of the material behavior of compacted granular materials is contingent upon the knowledge of microstructure formation, which is highly dependent on the bulk material properties and processing conditions, during the deformation stage. Originating from the pair interactions between particles, the macroscopic properties are obtained using various homogenization techniques and postulating continuum constitutive laws. While pioneers in this field have laid fundamental groundwork regarding effective medium descriptions, there exists a discrepancy between discrete and continuum level solutions. In our previous work, we elaborated a Particle Mechanics Approach (PMA) that integrates thermal contact and Hertzian deformation models to understand the thermo-mechanically-coupled consolidation problem. We also considered the analogous problem from the perspective of the conventional Continuum Mechanics Approach (CMA). In this study, following the multi-scale modeling framework, we propose an effective thermal expansion coefficient for the thermally-assisted compaction of granular materials.

  19. The effect of allometric scaling in coral thermal microenvironments.

    Directory of Open Access Journals (Sweden)

    Robert H Ong

    Full Text Available A long-standing interest in marine science is in the degree to which environmental conditions of flow and irradiance, combined with optical, thermal and morphological characteristics of individual coral colonies, affects their sensitivity of thermal microenvironments and susceptibility to stress-induced bleaching within and/or among colonies. The physiological processes in Scleractinian corals tend to scale allometrically as a result of physical and geometric constraints on body size and shape. There is a direct relationship between scaling to thermal stress, thus, the relationship between allometric scaling and rates of heating and cooling in coral microenvironments is a subject of great interest. The primary aim of this study was to develop an approximation that predicts coral thermal microenvironments as a function of colony morphology (shape and size, light or irradiance, and flow velocity or regime. To do so, we provided intuitive interpretation of their energy budgets for both massive and branching colonies, and then quantified the heat-size exponent (b* and allometric constant (m using logarithmic linear regression. The data demonstrated a positive relationship between thermal rates and changes in irradiance, A/V ratio, and flow, with an interaction where turbulent regime had less influence on overall stress which may serve to ameliorate the effects of temperature rise compared to the laminar regime. These findings indicated that smaller corals have disproportionately higher stress, however they can reach thermal equilibrium quicker. Moreover, excellent agreements between the predicted and simulated microscale temperature values with no significant bias were observed for both the massive and branching colonies, indicating that the numerical approximation should be within the accuracy with which they could be measured. This study may assist in estimating the coral microscale temperature under known conditions of water flow and irradiance

  20. Electrical stimulation vs thermal effects in a complex electromagnetic environment.

    Science.gov (United States)

    Paniagua, Jesús M; Rufo, Montaña; Jiménez, Antonio; Antolín, Alicia; Sánchez, Miguel

    2009-08-01

    Studies linking exposure to low levels of radiofrequencies with adverse health effects, notwithstanding their present apparent inconsistency, have contributed to a steady improvement in the quality of evaluating that exposure. In complex electromagnetic environments, with a multitude of emissions of different frequencies acting simultaneously, knowledge of the spectral content is fundamental to evaluating human exposure to non-ionizing radiation. In the present work, we quantify the most significant spectral components in the frequency band 0.5-2200 MHz in an urban area. The measurements were made with a spectrum analyzer and monopole, biconical, and log-periodic antennas. Power density levels were calculated separately for the medium wave, short wave, and frequency modulation radio broadcasting bands, and for the television and GSM, DCS, and UMTS mobile telephony bands. The measured levels were compared with the ICNIRP reference levels for exposure to multiple frequency sources for thermal effects and electrical stimulation. The results showed the criterion limiting exposure on the basis of preventing electrical stimulation of peripheral nerves and muscles to be stricter (exposure quotient 24.7 10(-4)) than that based on thermal considerations (exposure quotient 0.16 10(-4)). The bands that contribute most to the latter are short wave, with 46.2%, and mobile telephony with 32.6% of the total exposure. In a complex electromagnetic environment, knowledge of the radiofrequency spectrum is essential in order to quantify the contribution of each type of emission to the public's exposure. It is also necessary to evaluate the electrical effects as well as the thermal effects because the criterion to limit exposure on the basis of the effect of the electrical stimulation of tissues is stricter than that based on thermal effects.

  1. Electrical stimulation vs thermal effects in a complex electromagnetic environment

    Energy Technology Data Exchange (ETDEWEB)

    Paniagua, Jesus M., E-mail: paniagua@unex.es [Department of Applied Physics, Polytechnic School, University of Extremadura. Avda. de la Universidad s/n, 10071 Caceres (Spain); Rufo, Montana; Jimenez, Antonio; Antolin, Alicia; Sanchez, Miguel [Department of Applied Physics, Polytechnic School, University of Extremadura. Avda. de la Universidad s/n, 10071 Caceres (Spain)

    2009-08-01

    Studies linking exposure to low levels of radiofrequencies with adverse health effects, notwithstanding their present apparent inconsistency, have contributed to a steady improvement in the quality of evaluating that exposure. In complex electromagnetic environments, with a multitude of emissions of different frequencies acting simultaneously, knowledge of the spectral content is fundamental to evaluating human exposure to non-ionizing radiation. In the present work, we quantify the most significant spectral components in the frequency band 0.5-2200 MHz in an urban area. The measurements were made with a spectrum analyzer and monopole, biconical, and log-periodic antennas. Power density levels were calculated separately for the medium wave, short wave, and frequency modulation radio broadcasting bands, and for the television and GSM, DCS, and UMTS mobile telephony bands. The measured levels were compared with the ICNIRP reference levels for exposure to multiple frequency sources for thermal effects and electrical stimulation. The results showed the criterion limiting exposure on the basis of preventing electrical stimulation of peripheral nerves and muscles to be stricter (exposure quotient 24.7 10{sup -4}) than that based on thermal considerations (exposure quotient 0.16 10{sup -4}). The bands that contribute most to the latter are short wave, with 46.2%, and mobile telephony with 32.6% of the total exposure. In a complex electromagnetic environment, knowledge of the radiofrequency spectrum is essential in order to quantify the contribution of each type of emission to the public's exposure. It is also necessary to evaluate the electrical effects as well as the thermal effects because the criterion to limit exposure on the basis of the effect of the electrical stimulation of tissues is stricter than that based on thermal effects.

  2. Effects of thermal environment on sleep and circadian rhythm

    Directory of Open Access Journals (Sweden)

    Okamoto-Mizuno Kazue

    2012-05-01

    Full Text Available Abstract The thermal environment is one of the most important factors that can affect human sleep. The stereotypical effects of heat or cold exposure are increased wakefulness and decreased rapid eye movement sleep and slow wave sleep. These effects of the thermal environment on sleep stages are strongly linked to thermoregulation, which affects the mechanism regulating sleep. The effects on sleep stages also differ depending on the use of bedding and/or clothing. In semi-nude subjects, sleep stages are more affected by cold exposure than heat exposure. In real-life situations where bedding and clothing are used, heat exposure increases wakefulness and decreases slow wave sleep and rapid eye movement sleep. Humid heat exposure further increases thermal load during sleep and affects sleep stages and thermoregulation. On the other hand, cold exposure does not affect sleep stages, though the use of beddings and clothing during sleep is critical in supporting thermoregulation and sleep in cold exposure. However, cold exposure affects cardiac autonomic response during sleep without affecting sleep stages and subjective sensations. These results indicate that the impact of cold exposure may be greater than that of heat exposure in real-life situations; thus, further studies are warranted that consider the effect of cold exposure on sleep and other physiological parameters.

  3. Effects of Thermal Tension Transients on the Muscle Crossbridge

    Science.gov (United States)

    Greene, Peter R.

    2016-09-01

    The transverse thermal fluctuations of the myosin molecule are significant. This paper explores the contribution of lateral myosin bending to the developed crossbridge force and power stroke. The equipartition theorem is used to calculate the mode amplitudes for myosin bending. Crossbridge axial force Fx and power stroke Δx are developed by transverse in-plane fluctuations along the y- and z-axes. Practical applications include the effects of temperature on the flexibility of the myosin molecule stiffness and tension, relevant to man-made fabrication of synthetic muscle using micromachines and nanowires. Scaling laws for the S2 bending amplitude depend on filament length, mode number, and stiffness, as n-2,L2, and (EI)-1. This paper quantifies the effects of thermal motion on the mechanics of miniature molecular motors, including the muscle crossbridge.

  4. Pressure Effects on the Thermal De-NOx Process

    DEFF Research Database (Denmark)

    Kjærgaard, Karsten; Glarborg, Peter; Dam-Johansen, Kim

    1996-01-01

    The effect of pressure on the thermal de-NOx process has been investigated in flow reactor experiments. The experiments were performed at pressures from 1 to 10 bar and temperatures ranging from 925 to 1375 K. The inlet O-2 level was varied from 1000 ppm to 10%, while NH3 and NO were maintained...... effect of the pressure but also cause a slight decrease in the NO reduction potential. The results are consistent with recent atmospheric pressure experiments of thermal de-NOx covering a wide range of reactant partial pressures. Comparisons of the experimental data with the recent chemical kinetic model...... at 1000 and 500 ppm, respectively At the highest pressure, CO was added to shift the regime for NO reduction to lower temperatures. The results show that the pressure affects the location and the width of the temperature window for NO reduction. As the pressure is increased, both the lower and the higher...

  5. Ordered Pinning Arrays with Tunable Geometry via Thermal Effects

    Science.gov (United States)

    Trastoy, Juan; Bernard, Rozenn; Briatico, Javier; Villegas, Javier E.; Malnou, Maxime; Bergeal, Nicolas; Lesueur, Jerome; Ulysse, Christian; Faini, Giancarlo

    2015-03-01

    We have used geometrically frustrated pinning arrays to create artificial vortex-ice. The pinning arrays are fabricated via ion irradiation of high-Tc superconducting films. These arrays present a very unique characteristic: the frustration can be reversibly switched on/off using temperature as a control knob, which allows stabilizing either a vortex-ice or a square vortex lattice. We have further investigated the thermal switching mechanism by studying the matching of the flux lattice to arrays that are incrementally deformed upon fabrication by introducing minute variations of the distance between pins. The array deformation exacerbates the thermal effects, leading to dramatic variations of the vortex distribution as a function of temperature. These results illustrate the strength of the temperature-induced reconfiguration effects, which may constitute a novel knob in fluxtronic devices based on vortex manipulation. Work supported by the French ANR MASTHER, the COST Action NanoSC, the Ville de Paris and the Galician Fundacion Barrie.

  6. Influence of thermal effects on stability of nanoscale films and filaments on thermally conductive substrates

    Science.gov (United States)

    Seric, Ivana; Afkhami, Shahriar; Kondic, Lou

    2018-01-01

    We consider fluid films and filaments of nanoscale thickness on thermally conductive substrates exposed to external heating and discuss the influence of the variation of material parameters with temperature on film stability. Particular focus is on metal films exposed to laser irradiation. Due to the short length scales involved, the absorption of heat in the metal is directly coupled to the film evolution, since the absorption length and the film thickness are comparable. Such a setup requires self-consistent consideration of fluid mechanical and thermal effects. We approach the problem via volume-of-fluid-based simulations that include destabilizing liquid metal-solid substrate interaction potentials. These simulations couple fluid dynamics directly with the spatio-temporal evolution of the temperature field both in the fluid and in the substrate. We focus on the influence of the temperature variation of material parameters, in particular of surface tension and viscosity. Regarding variation of surface tension with temperature, the main finding is that while the Marangoni effect may not play a significant role in the considered setting, the temporal variation of surface tension (modifying normal stress balance) is significant and could lead to complex evolution including oscillatory evolution of the liquid metal-air interface. Temperature variation of film viscosity is also found to be relevant. Therefore, the variations of surface tensions and viscosity could both influence the emerging wavelengths in experiments. By contrast, the filament geometry is found to be much less sensitive to a variation of material parameters with temperature.

  7. A review on ergonomics of headgear: Thermal effects

    OpenAIRE

    Bogerd, C.P.; Aerts, J.M.; Annaheim, S.; Bröde, P.; Bruyne, G. de; Flouris, A.D.; Kuklane, K.; Sotto Mayor, T.; Rossi, R.M.

    2015-01-01

    The thermal effects related to wearing headgear are complex and different studies have investigated single parts of this topic. This review aims at summarizing the different findings to give a complete overview on this topic as well as to suggest new perspectives. Headgear increases head insulation and therefore is mainly problematic under warm conditions, which is the focus of this review. Helmets do not affect physiological parameters other than the local skin temperature and sweat rate. Ho...

  8. Tuning the thermal conductance of molecular junctions with interference effects

    Science.gov (United States)

    Klöckner, J. C.; Cuevas, J. C.; Pauly, F.

    2017-12-01

    We present an ab initio study of the role of interference effects in the thermal conductance of single-molecule junctions. To be precise, using a first-principles transport method based on density functional theory, we analyze the coherent phonon transport in single-molecule junctions made of several benzene and oligo(phenylene ethynylene) derivatives. We show that the thermal conductance of these junctions can be tuned via the inclusion of substituents, which induces destructive interference effects and results in a decrease of the thermal conductance with respect to the unmodified molecules. In particular, we demonstrate that these interference effects manifest as antiresonances in the phonon transmission, whose energy positions can be tuned by varying the mass of the substituents. Our work provides clear strategies for the heat management in molecular junctions and, more generally, in nanostructured metal-organic hybrid systems, which are important to determine how these systems can function as efficient energy-conversion devices such as thermoelectric generators and refrigerators.

  9. Topological thermal Hall effect in frustrated kagome antiferromagnets

    Science.gov (United States)

    Owerre, S. A.

    2017-01-01

    In frustrated magnets the Dzyaloshinsky-Moriya interaction (DMI) arising from spin-orbit coupling can induce a magnetic long-range order. Here, we report a theoretical prediction of the thermal Hall effect in frustrated kagome magnets such as KCr3(OH) 6(SO4) 2 and KFe3(OH) 6(SO4)2 . The thermal Hall effects in these materials are induced by scalar spin chirality as opposed to DMI in previous studies. The scalar spin chirality originates from the magnetic-field-induced chiral spin configuration due to noncoplanar spin textures, but in general it can be spontaneously developed as a macroscopic order parameter in chiral quantum spin liquids. Therefore, we infer that there is a possibility of the thermal Hall effect in frustrated kagome magnets such as herbertsmithite ZnCu3(OH) 6Cl2 and the chromium compound Ca10Cr7O28 , although they also show evidence of magnetic long-range order in the presence of applied magnetic field or pressure.

  10. Imaging laser-induced thermal fields and effects

    Science.gov (United States)

    Verdaasdonck, Rudolf M.

    1995-05-01

    Laser light interaction with biological tissues is a combination of optical, thermal and mechanical effects depending on the energy applied per unit of volume per unit of time. Visualization of the phenomena with a high temporal and spatial resolution, contributes to a better understanding of the mechanism of action, especially when pulsed lasers are involved. For this goal, setups were developed based on Schlieren techniques to image the interaction of pulsed (CO2, Holmium and Excimer) and CW (CO2, Nd:YAG, Cu-vapor) lasers with physiological media and biological tissues. In a 'fast' Schlieren setup, images of shock waves and fast expanding and imploding vapor bubbles were captured using very short light flashes (10 ns-10 microseconds). These recordings suggest that these explosive vapor bubbles seem to be the main dynamism for tissue ablation. In a 'color' Schlieren setup, very small changes in optical density of the media induced by temperature gradients, were color coded. Calibration of the color images to absolute temperatures were performed by using calculated temperature distributions and by thermocouple measurements. Cameras with high speed shutters (0.1-50 ms) enabled the recording of dynamic images of the thermal relaxation and heat diffusion in tissues during variation of pulse length and repetition rate. Despite pulse lengths Schlieren techniques were applied to study the thermal characteristics of laser probes, e.g. for the treatment of Benign Prostatic Hyperplasia (BPH). In combination with thermal modeling an optimal therapy might be predicted. Schlieren techniques, generating high-speed and 'thermal' images, can provide a good understanding of the ablation mechanism and the thermo-dynamics during laser-tissue interaction with continuous wave and pulse lasers.

  11. Effective Thermal Conductivity of Graphite Materials with Cracks

    Science.gov (United States)

    Pestchaanyi, S. E.; Landman, I. S.

    The dependence of effective thermal diffusivity on temperature caused by volumetric cracks is modelled for macroscopic graphite samples using the three-dimensional thermomechanics code Pegasus-3D. At high off-normal heat loads typical of the divertor armour, thermostress due to the anisotropy of graphite grains is much larger than that due to the temperature gradient. Numerical simulation demonstrated that the volumetric crack density both in fine grain graphites and in the CFC matrix depends mainly on the local sample temperature, not on the temperature gradient. This allows to define an effective thermal diffusivity for graphite with cracks. The results obtained are used to explain intense cracking and particle release from carbon based materials under electron beam heat load. Decrease of graphite thermal diffusivity with increase of the crack density explains particle release mechanism in the experiments with CFC where a clear energy threshold for the onset of particle release has been observed in J. Linke et al. Fusion Eng. Design, in press, Bazyler et al., these proceedings. Surface temperature measurement is necessary to calibrate the Pegasus-3D code for simulation of ITER divertor armour brittle destruction.

  12. Thermal Stress Effect on Density Changes of Hemp Hurds Composites

    Science.gov (United States)

    Schwarzova, Ivana; Cigasova, Julia; Stevulova, Nadezda

    2016-12-01

    The aim of this article is to study the behavior of prepared biocomposites based on hemp hurds as a filling agent in composite system. In addition to the filler and water, an alternative binder, called MgO-cement was used. For this objective were prepared three types of samples; samples based on untreated hemp hurds as a referential material and samples based on chemically (with NaOH solution) and physically (by ultrasonic procedure) treated hemp hurds. The thermal stress effect on bulk density changes of hemp hurds composites was monitored. Gradual increase in temperature led to composites density reduction of 30-40 %. This process is connected with mass loss of the adsorbed moisture and physically bound water and also with degradation of organic compounds present in hemp hurds aggregates such as pectin, hemicelluloses and cellulose. Therefore the changes in the chemical composition of treated hemp hurds in comparison to original sample and its thermal decomposition were also studied.

  13. Thermal effects in high average power optical parametric amplifiers.

    Science.gov (United States)

    Rothhardt, Jan; Demmler, Stefan; Hädrich, Steffen; Peschel, Thomas; Limpert, Jens; Tünnermann, Andreas

    2013-03-01

    Optical parametric amplifiers (OPAs) have the reputation of being average power scalable due to the instantaneous nature of the parametric process (zero quantum defect). This Letter reveals serious challenges originating from thermal load in the nonlinear crystal caused by absorption. We investigate these thermal effects in high average power OPAs based on beta barium borate. Absorption of both pump and idler waves is identified to contribute significantly to heating of the nonlinear crystal. A temperature increase of up to 148 K with respect to the environment is observed and mechanical tensile stress up to 40 MPa is found, indicating a high risk of crystal fracture under such conditions. By restricting the idler to a wavelength range far from absorption bands and removing the crystal coating we reduce the peak temperature and the resulting temperature gradient significantly. Guidelines for further power scaling of OPAs and other nonlinear devices are given.

  14. Effect of thermal power plant emissions on Catharanthus roseus L

    Energy Technology Data Exchange (ETDEWEB)

    Khan, A.M.; Pandey, V.; Shukla, J.; Singh, N.; Yunus, M.; Singh, S.N.; Ahmad, K.J. (National Botanical Research Institute, Lucknow (India))

    1990-06-01

    Most of the industrialized nations depend largely on the combustion of fossil fuels for their energy requirements. During the past few years in India quite a few thermal power plants have been commissioned to cater to the increasing energy requirements. As most of the power plants are coal-fired, a complex mixture of several pollutants is released in the atmosphere on the combustion of coal. Leaves by virtue of their unique position on plants and their functions, experience the maximum brunt of exposure and undergo certain changes in form, structure and function with the changes in surrounding environs, and such modifications are likely to serve as markers of environmental pollution. The present paper deals with the long term exposure effects of thermal power plant emissions on Catharanthus roseus L. - a common perennial shrub, with glossy leaves and white, mauve or pink colored flowers and of great medicinal value is grown as an ornamental plant all over the country.

  15. Effective permittivity of saline ice under thermal variation

    Science.gov (United States)

    Nghiem, S. V.; Kwok, R.; Kong, J. A.; Shin, R. T.; Gow, A. J.; Arcone, S. A.

    1992-01-01

    A model for calculating the effective permittivity of saline ice under thermal variation is presented. The model includes multiphase inhomogeneities with multiple species characterized by orientation, size and shape distributions. The model is used to derive the effective permittivity as a function of temperature under the strong fluctuation theory which is extended to account for the complexity. The results calculated from the model are compared with experimental data at 4.8 GHz for saline ice grown at the US Army Cold Regions Research and Engineering Laboratory (CRREL). The comparison between measured and calculated complex permittivities is good for the imaginary part, and the difference is within 10 percent for the real part.

  16. Thermal processing of EVA encapsulants and effects of formulation additives

    Energy Technology Data Exchange (ETDEWEB)

    Pern, F.J.; Glick, S.H. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    The authors investigated the in-situ processing temperatures and effects of various formulation additives on the formation of ultraviolet (UV) excitable chromophores, in the thermal lamination and curing of ethylene-vinyl acetate (EVA) encapsulants. A programmable, microprocessor-controlled, double-bag vacuum laminator was used to study two commercial as formulated EVA films, A9918P and 15295P, and solution-cast films of Elvaxrm (EVX) impregnated with various curing agents and antioxidants. The results show that the actual measured temperatures of EVA lagged significantly behind the programmed profiles for the heating elements and were affected by the total thermal mass loaded inside the laminator chamber. The antioxidant Naugard P{trademark}, used in the two commercial EVA formulations, greatly enhances the formation of UV-excitable, short chromophores upon curing, whereas other tested antioxidants show little effect. A new curing agent chosen specifically for the EVA formulation modification produces little or no effect on chromophore formation, no bubbling problems in the glass/EVX/glass laminates, and a gel content of {approximately}80% when cured at programmed 155{degrees}C for 4 min. Also demonstrated is the greater discoloring effect with higher concentrations of curing-generated chromophores.

  17. Finite-temperature effective boundary theory of the quantized thermal Hall effect

    OpenAIRE

    Nakai, Ryota; Ryu, Shinsei; Nomura, Kentaro

    2015-01-01

    A finite-temperature effective free energy of the boundary of a quantized thermal Hall system is derived microscopically from the bulk two-dimensional Dirac fermion coupled with a gravitational field. In two spatial dimensions, the thermal Hall conductivity of fully gapped insulators and superconductors is quantized and given by the bulk Chern number, in analogy to the quantized electric Hall conductivity in quantum Hall systems. From the perspective of effective action functionals, two disti...

  18. Nonlinear model for thermal effects in free-electron lasers

    OpenAIRE

    Peter, Eduardo Alcides; Endler, Antônio; Rizzato, Felipe Barbedo

    2014-01-01

    In the present work, we extend results of a previous paper [Peter et al., Phys. Plasmas 20, 12 3104 (2013)] and develop a semi-analytical model to account for thermal effects on the nonlinear dynamics of the electron beam in free-electron lasers. We relax the condition of a cold electron beam but still use the concept of compressibility, now associated with a warm beam model, to evaluate the time scale for saturation and the peak laser intensity in high-gain regimes. Although vanishing compre...

  19. Thermal enhancement of interference effects in quantum point contacts.

    Science.gov (United States)

    Abbout, Adel; Lemarié, Gabriel; Pichard, Jean-Louis

    2011-04-15

    We study an electron interferometer formed with a quantum point contact and a scanning probe tip in a two-dimensional electron gas. The images giving the conductance as a function of the tip position exhibit fringes spaced by half the Fermi wavelength. For a contact opened at the edges of a quantized conductance plateau, the fringes are enhanced as the temperature T increases and can persist beyond the thermal length l(T). This unusual effect is explained by assuming a simplified model: The fringes are mainly given by a contribution which vanishes when T→0 and has a decay characterized by a T-independent scale.

  20. Thermal Enhancement of Interference Effects in Quantum Point Contacts

    OpenAIRE

    Abbout, Adel; Lemarié, Gabriel; Pichard, Jean-Louis

    2010-01-01

    We study an electron interferometer formed with a quantum point contact and a scanning probe tip in a two-dimensional electron gas. The images giving the conductance as a function of the tip position exhibit fringes spaced by half the Fermi wavelength. For a contact opened at the edges of a quantized conductance plateau, the fringes are enhanced as the temperature T increases and can persist beyond the thermal length l_T. This unusual effect is explained assuming a simplified model: The fring...

  1. Electro-optical characteristics of indium tin oxide (ITO) films: effect of thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, D.V.; Salehi, A.; Aliyu, Y.H.; Bunce, R.W. [University of Wales College of Cardiff (United Kingdom). School of Electrical, Electronics and System Engineering

    1996-02-01

    The effect of thermal annealing on the electrical and optical characteristics of ITO films prepared by reactive sputtering and thermal evaporation have been studied. The effect of the thermal annealing is to improve the conductivity and the optical transmission in the shorter wavelength region. The conductivity of the films increases with annealing temperature, this behaviour is associated with grain growth in the film. (author)

  2. Evaluation of different measurements for effective thermal conductivity of fibrous materials

    Directory of Open Access Journals (Sweden)

    Tian Ming-Wei

    2014-01-01

    Full Text Available Effective thermal conductivity is generally recognized as the intrinsic factor to reveal the thermal responses of fibrous materials. Here, two typical measurements, the step-wise transient method and the guarded hot plate method, were utilized to identify their feasibility for the effective thermal conductivity of fibrous materials (non-woven fabric and twill fabric with different stacking layers.

  3. Effect of composition on thermal conductivity of silica insulation media.

    Science.gov (United States)

    Park, Sung; Kwon, Young-Pil; Kwon, Hyuk-Chon; Lee, Hae-Weon; Lee, Jae Chun

    2008-10-01

    Nano-sized fumed silica-based insulation media were prepared by adding TiO2 powders and ceramic fibers as opacifiers and structural integrity improvers, respectively. The high temperature thermal conductivities of the fumed silica-based insulation media were investigated using different types of TiO2 opacifier and by varying its content. The opacifying effects of nanostructured TiO2 powders produced by homogeneous precipitation process at low temperatures (HPPLT) were compared with those of commercial TiO2 powder. The nanostructured HPPLT TiO2 powder with a mean particle size of 1.8 microm was more effective to reduce radiative heat transfer than the commercial one with a similar mean particle size. The insulation samples with the HPPLT TiO2 powder showed about 46% lower thermal conductivity at temperatures of about 820 degrees C than those with the commercial one. This interesting result might be due to the more effective radiation scattering efficiency of the nanostructured HPPLT TiO2 powder which has better gap filling and coating capability in nano-sized composite compacts.

  4. Ion thermal and dispersion effects in Farley-Buneman instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Litt, S. K., E-mail: sandeep.litt@usask.ca; Smolyakov, A. I., E-mail: andrei.smolyakov@usask.ca [Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 (Canada); Hassan, E., E-mail: ehab@utexas.edu [Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States); Department of Physics, Ain Shams University, Cairo (Egypt); Horton, W., E-mail: wendell.horton@gmail.com [Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States); Applied Research Laboratory, University of Texas at Austin, Austin, Texas 78758 (United States)

    2015-08-15

    Farley-Buneman modes are an example of the collisional instability, which is thought to be the dominant mechanism for the irregularities in low ionosphere region. Despite high collisionality due to electron-neutral and ion-neutral collisions, the kinetic effects associated with finite temperature are important for determination of the mode frequencies and growth rate. This is especially important for ion component that is largely unmagnetized due to low ion cyclotron frequency. The ion thermal effects are strongly pronounced for shorter wavelengths and are crucial for the growth rate cut-off at high wavenumbers. We develop an extended fluid model for ion dynamics to incorporate the effects of ion thermal motion. The model is based on the extended MHD model that includes the evolution equations for higher order moments such as ion viscosity and ion heat flux. We also develop the generalized Chapman-Enskog closure model that provides exact linear closures based on the linearized kinetic equation. The results of these models are compared and tested against the linear kinetic model. The dispersion of Farley-Buneman modes and growth rate behavior are investigated in the short wavelength region.

  5. Thermal gradients in Southwestern United States and the effect on bridge bearing loads : final report.

    Science.gov (United States)

    2017-05-01

    Thermal gradients became a component of bridge design after soffit cracking in prestressed concrete bridges was attributed to nonlinear temperature distribution through the depth of the bridge. While the effect of thermal gradient on stress distribut...

  6. Effective thermal conductivity and thermal contact resistance of gas diffusion layers in proton exchange membrane fuel cells. Part 2: Hysteresis effect under cyclic compressive load

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, E. [Dept. Mechanical Eng., and Institute for Integrated Energy Systems, University of Victoria, P.O. Box 3055, Victoria, BC (Canada); Mechatronic Systems Engineering, School of Engineering Science, Simon Fraser University, Surrey, BC (Canada); Djilali, N. [Dept. Mechanical Eng., and Institute for Integrated Energy Systems, University of Victoria, P.O. Box 3055, Victoria, BC (Canada); Bahrami, M. [Mechatronic Systems Engineering, School of Engineering Science, Simon Fraser University, Surrey, BC (Canada)

    2010-12-15

    Heat transfer through the gas diffusion layer (GDL) is a key process in the design and operation of a PEM fuel cell. The analysis of this process requires the determination of the effective thermal conductivity as well as the thermal contact resistance between the GDL and adjacent surfaces/layers. The Part 1 companion paper describes an experimental procedure and a test bed devised to allow separation of the effective thermal conductivity and thermal contact resistance, and presents measurements under a range of static compressive loads. In practice, during operation of a fuel cell stack, the compressive load on the GDL changes. In the present study, experiments are performed on Toray carbon papers with 78% porosity and 5% PTFE under a cyclic compressive load. Results show a significant hysteresis in the loading and unloading cycle data for total thermal resistance, thermal contact resistance (TCR), effective thermal conductivity, thickness, and porosity. It is found that after 5 loading-unloading cycles, the geometrical, mechanical, and thermal parameters reach a ''steady-state'' condition and remain unchanged. A key finding of this study is that the TCR is the dominant component of the GDL total thermal resistance with a significant hysteresis resulting in up to a 34% difference between the loading and unloading cycle data. This work aims to clarify the impact of unsteady/cyclic compression on the thermal and structural properties of GDLs and provides new insights on the importance of TCR which is a critical interfacial transport phenomenon. (author)

  7. Investigating effect of different reflective surfaces on solar thermal collector

    Science.gov (United States)

    Chua, Yaw Long; Chin, Kiat Keong; Tay, Tee Tiong

    2017-11-01

    This paper reports on the experiments conducted to investigate the efficiency of different type of reflecting surfaces used on solar thermal collector. Three types of commonly available reflective surfaces coated with silver colour acrylic paint, reflective aluminium foil and blank compact disc are investigated. In this paper, the effect of different reflective surfaces on the water container and parabolic concentrator dish are investigated. In the first experiment, two types of surfaces, coated with silver colour acrylic paint and black colour acrylic paint on an aluminium container are compared. The other factors that might influence the experiment outcome like the material, focal point, and weather condition are kept constant. The experiment results proved that black colour surface is better in absorbing heat reflected by the parabolic dish. The second experiment focused on investigating the effect of different reflective surfaces on the parabolic concentrator dish itself. These surfaces are tested on a parabolic disc of a static solar thermal collector that reflects heat from the sun to a body of water stored in a black colour aluminium container. The temperature of the water is measured at a predetermined interval to measure the efficiency of the reflective surfaces used. It is found that the aluminium reflective surface performed the best compared to the other surfaces.

  8. Effects of thermal treatments on donkey milk nutritional characteristics.

    Science.gov (United States)

    Polidori, Paolo; Vincenzetti, Silvia

    2013-12-01

    Human breast milk is the best nutritional support to ensure right development and influence immune status of the newborn infant. However, when it is not possible to breast feed it may be necessary to use commercial infant formulas that mimic, where possible, the levels and types of nutrients present in human milk. Despite this, some formula-fed infants develop allergy and/or atopic disease compared to breast-fed infants. Most infants with cow's milk protein allergy (CMPA) develop symptoms before 1 month of age, often within 1 week after introduction of cow's milk-based formula. Donkey milk may be considered a good substitute for cow's milk in feeding children with CMPA since its composition is very similar to human milk. An in-depth analysis of the donkey milk protein profile has been performed in this study. The interest was focused on the milk proteins considered safe for the prevention and treatment of various disorders in human. Since donkey milk supply is related to its seasonal availability during the year, in this study were evaluated the effects of different thermal treatments on the protein fractions of donkey milk. The results obtained in fresh, frozen, powdered and lyophilized donkey milk showed different values in total proteins, caseins, whey proteins and lysozyme content. This study demonstrated the possibility of using lyophilization in order to maintain the nutritional characteristics of donkey milk. The article presents some promising patents on the effects of thermal treatments on donkey milk nutritional characteristics.

  9. MMOD Protection and Degradation Effects for Thermal Control Systems

    Science.gov (United States)

    Christiansen, Eric

    2014-01-01

    Micrometeoroid and orbital debris (MMOD) environment overview Hypervelocity impact effects & MMOD shielding MMOD risk assessment process Requirements & protection techniques - ISS - Shuttle - Orion/Commercial Crew Vehicles MMOD effects on spacecraft systems & improving MMOD protection - Radiators Coatings - Thermal protection system (TPS) for atmospheric entry vehicles Coatings - Windows - Solar arrays - Solar array masts - EVA Handrails - Thermal Blankets Orbital Debris provided by JSC & is the predominate threat in low Earth orbit - ORDEM 3.0 is latest model (released December 2013) - http://orbitaldebris.jsc.nasa.gov/ - Man-made objects in orbit about Earth impacting up to 16 km/s average 9-10 km/s for ISS orbit - High-density debris (steel) is major issue Meteoroid model provided by MSFC - MEM-R2 is latest release - http://www.nasa.gov/offices/meo/home/index.html - Natural particles in orbit about sun Mg-silicates, Ni-Fe, others - Meteoroid environment (MEM): 11-72 km/s Average 22-23 km/s.

  10. Effective thermal conductivity and thermal contact resistance of gas diffusion layers in proton exchange membrane fuel cells. Part 1: Effect of compressive load

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, E. [Dept. Mechanical Eng., and Institute for Integrated Energy Systems, University of Victoria, P.O. Box 3055, Victoria, BC (Canada); Mechatronic Systems Engineering, School of Engineering Science, Simon Fraser University, Surrey, BC (Canada); Djilali, N. [Dept. Mechanical Eng., and Institute for Integrated Energy Systems, University of Victoria, P.O. Box 3055, Victoria, BC (Canada); Bahrami, M. [Mechatronic Systems Engineering, School of Engineering Science, Simon Fraser University, Surrey, BC (Canada)

    2011-01-01

    Heat transfer through the gas diffusion layer (GDL) is a key process in the design and operation of a PEM fuel cell. The analysis of this process requires determination of the effective thermal conductivity as well as the thermal contact resistance associated with the interface between the GDL and adjacent surfaces/layers. In the present study, a custom-made test bed that allows the separation of effective thermal conductivity and thermal contact resistance in GDLs under vacuum and ambient conditions is described. Measurements under varying compressive loads are performed using Toray carbon paper samples with a porosity of 78% for a range of thicknesses. The measurements are complemented by compact analytical models that achieve good agreement with experimental data. A key finding is that thermal contact resistance is the dominant component of the total thermal resistance; neglecting this phenomenon may result in significant errors in evaluating heat transfer rates and temperature distributions. (author)

  11. Thermally and Electrically Conductive Nanopapers from Reduced Graphene Oxide: Effect of Nanoflakes Thermal Annealing on the Film Structure and Properties

    Directory of Open Access Journals (Sweden)

    M. Mar Bernal

    2017-12-01

    Full Text Available In this study, we report a novel strategy to prepare graphene nanopapers from direct vacuum filtration. Instead of the conventional method, i.e., thermal annealing nanopapers at extremely high temperatures prepared from graphene oxide (GO or partially reduced GO, we fabricate our graphene nanopapers directly from suspensions of fully reduced graphene oxide (RGO, obtained after RGO and thermal annealing at 1700 °C in vacuum. By using this approach, we studied the effect of thermal annealing on the physical properties of the macroscopic graphene-based papers. Indeed, we demonstrated that the enhancement of the thermal and electrical properties of graphene nanopapers prepared from annealed RGO is strongly influenced by the absence of oxygen functionalities and the morphology of the nanoflakes. Hence, our methodology can be considered as a valid alternative to the classical approach.

  12. Bactericidal effects of reactive thermal plasma synthesized titanium dioxide photocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Vijay, M [Plasma Physics Laboratory, Department of Physics, Bharathiar University, Coimbatore 641046 (India); Ananthapadmanabhan, P V; Sreekumar, K P [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Stengl, Vaclav [Institute of Inorganic Chemistry, AS CR, v.v.i., 250 68 Rez (Czech Republic); Bondioli, Federica [Dipartimento di Ingegneria dei Materiali e dell' Ambiente, Universita di Modena e Reggio Emilia, Via Vignolese 905 - 41100 Modena (Italy); Selvarajan, V, E-mail: vselvrjn47@rediffmail.co

    2010-02-01

    Nanocrystalline titanium oxide powder has been synthesized by reactive plasma processing. The precursor powder of TiH{sub 2} was oxidized 'in-flight' in a thermal plasma reactor to effect complete conversion of TiH{sub 2} to nano-sized TiO{sub 2} powder. Characterization of the powder by various analytical tools indicated that the powder consisted of nano-sized titanium dioxide particles consisting predominantly of the anatase phase. Bactericidal action of illuminated TiO{sub 2} on pure culture of Escherichia coli was studied. The plasma synthesized TiO{sub 2}nano powder catalyst was found to be highly effective for the killing of Escherichia coli. The efficiency of photocatalytic disinfection, used to inactivate Escherischia coli as function of time is discussed.

  13. Thermal, Squeezing and Compressibility Effects in Lubrication of Asymmetric Rollers

    Directory of Open Access Journals (Sweden)

    D. Prasad

    2014-09-01

    Full Text Available Hydrodynamically heavily loaded rigid cylindrical rollers, lubricated by a thin compressible fluid film, are investigated for normal squeezing motion and cavitations. The lubricant is assumed to follow the non-Newtonian power-law fluid model where consistency and density of the lubricant vary with one dimensional pressure and temperature. The modified Reynolds pressure equation and thermal energy equation are derived and solved simultaneously by R-K Fehlberg method. Secant method is also applied in order to enforce the boundary condition at the outlet. It is observed that temperature has significant effects on consistency and density both. It is also to be noted that compressibility effect is even more significant when squeezing is taken into account.

  14. Effect of the environmental stimuli upon the human body in winter outdoor thermal environment

    DEFF Research Database (Denmark)

    Sakoi, Tomonori; Kondo, Emi; Ishii, Jin

    2013-01-01

    the psychological thermal responses of the human body and winter outdoor thermal environment variables. Subjective experiments were conducted in the winter outdoor environment. Environmental factors and human psychological responses were measured. The relationship between the psychological thermal responses...... of the human body and the outdoor thermal environment index ETFe (enhanced conduction-corrected modified effective temperature) in winter was shown. The variables which influence the thermal sensation vote of the human body are air temperature, long-wave thermal radiation and short-wave solar radiation....... The variables that influence the thermal comfort vote of the human body are air temperature, humidity, short-wave solar radiation, long-wave thermal radiation, and heat conduction. Short-wave solar radiation, and heat conduction are among the winter outdoor thermal environment variables that affect...

  15. Thermal resistances of air in cavity walls and their effect upon the thermal insulation performance

    Energy Technology Data Exchange (ETDEWEB)

    Bekkouche, S.M.A.; Cherier, M.K.; Hamdani, M.; Benamrane, N. [Application of Renewable Energies in Arid and Semi Arid Environments /Applied Research Unit on Renewable Energies/ EPST Development Center of Renewable Energies, URAER and B.P. 88, ZI, Gart Taam Ghardaia (Algeria); Benouaz, T. [University of Tlemcen, BP. 119, Tlemcen R.p. 13000 (Algeria); Yaiche, M.R. [Development Center of Renewable Energies, CDER and B.P 62, 16340, Route de l' Observatoire, Bouzareah, Algiers (Algeria)

    2013-07-01

    The optimum thickness in cavity walls in buildings is determined under steady conditions; the heat transfer has been calculated according to ISO 15099:2003. Two forms of masonry units are investigated to conclude the advantage of high thermal emissivity. The paper presents also some results from a study of the thermal insulation performance of air cavities bounded by thin reflective material layer 'eta = 0.05'. The results show that the most economical cavity configuration depends on the thermal emissivity and the insulation material used.

  16. Electric field effects in combustion with non-thermal plasma

    Science.gov (United States)

    Casey, Tiernan Albert

    Chemically reacting zones such as flames act as sources of charged species and can thus be considered as weakly-ionized plasmas. As such, the action of an externally applied electric field has the potential to affect the dynamics of reaction zones by enhancing transport, altering the local chemical composition, activating reaction pathways, and by providing additional thermal energy through the interaction of electrons with neutral molecules. To investigate these effects, one-dimensional simulations of reacting flows are performed including the treatment of charged species transport and non-thermal electron chemistry using a modified reacting fluid solver. A particular area of interest is that of plasma assisted ignition, which is investigated in a canonical one-dimensional configuration. An incipient ignition kernel, formed by localized energy deposition into a lean mixture of methane and air at atmospheric pressure, is subjected to sub-breakdown electric fields by applied voltages across the domain, resulting in non-thermal behavior of the electron sub-fluid formed during the discharge. Strong electric fields cause charged species to be rapidly transported from the ignition zone across the domain in opposite directions as charge fronts, augmenting the magnitude of the electric field in the fresh gas during the pulse through a dynamic-electrode effect. This phenomenon results in an increase in the energy of the electrons in the fresh mixture with increasing time, accelerating electron impact dissociation processes. A semi-analytic model to represent this dynamic electrode effect is constructed to highlight the relative simplicity of the electrodynamic problem admitted by the far more detailed chemistry and transport. Enhanced fuel and oxidizer decomposition due to electron impact dissociation and interaction with excited neutrals generate a pool of radicals, mostly O and H, in the fresh gas ahead of the flame's preheat zone. The effect of nanosecond pulses are to

  17. Effect of microstructure of graphite on the nonreductive thermal ion emission in thermal ionization mass spectrometry.

    Science.gov (United States)

    Wei, H Z; Jiang, S Y; Xiao, Y K

    2010-02-25

    The emission behavior of polyatomic ions in the ionization source of thermal ionization mass spectrometry (TIMS) was investigated. The results suggest that the presence of a graphite promoter plays a key role for the formation and stable emission of polyatomic ions, such as M(2)X(+), M(2)BO(2)(+), Cs(2)NO(2)(+), and Cs(2)CNO(+). Our data further implied that the intensity of M(2)X(+) and M(2)BO(2)(+) increases and the emission temperature decreases with increasing cationic and anionic radius. During the boron isotopic measurement using the Cs(2)BO(2)(+)-graphite-PTIMS method, the isobaric interference ion Cs(2)CNO(+) cannot be transformed from nitrate or organic compounds containing an amide group but can be induced by the existence of trace amounts of boron because of its special electron-deficiency property (B(3+)). Characterization on the planar crystalline structure of various graphite samples with SEM, TEM, and Raman spectroscopy confirmed the relationship of the emission capacity of polyatomic ions and the crystal microstructure of graphite and provides direct evidence that graphite with a perfect parallel and equidistant layer orientation shows a beneficial effect on the emission of polyatomic ions in TIMS. The mechanism study on the formation of polyatomic ions opens the possibility to establish high precision methods for isotopic composition analysis of more nonmetal elements with the TIMS technique.

  18. Thermal Stress Effect on Density Changes of Hemp Hurds Composites

    Directory of Open Access Journals (Sweden)

    Schwarzova Ivana

    2016-12-01

    Full Text Available The aim of this article is to study the behavior of prepared biocomposites based on hemp hurds as a filling agent in composite system. In addition to the filler and water, an alternative binder, called MgO-cement was used. For this objective were prepared three types of samples; samples based on untreated hemp hurds as a referential material and samples based on chemically (with NaOH solution and physically (by ultrasonic procedure treated hemp hurds. The thermal stress effect on bulk density changes of hemp hurds composites was monitored. Gradual increase in temperature led to composites density reduction of 30-40 %. This process is connected with mass loss of the adsorbed moisture and physically bound water and also with degradation of organic compounds present in hemp hurds aggregates such as pectin, hemicelluloses and cellulose. Therefore the changes in the chemical composition of treated hemp hurds in comparison to original sample and its thermal decomposition were also studied.

  19. Thermal stability of the krypton Hall effect thruster

    Directory of Open Access Journals (Sweden)

    Szelecka Agnieszka

    2017-03-01

    Full Text Available The Krypton Large IMpulse Thruster (KLIMT ESA/PECS project, which has been implemented in the Institute of Plasma Physics and Laser Microfusion (IPPLM and now is approaching its final phase, was aimed at incremental development of a ~500 W class Hall effect thruster (HET. Xenon, predominantly used as a propellant in the state-of-the-art HETs, is extremely expensive. Krypton has been considered as a cheaper alternative since more than fifteen years; however, to the best knowledge of the authors, there has not been a HET model especially designed for this noble gas. To address this issue, KLIMT has been geared towards operation primarily with krypton. During the project, three subsequent prototype versions of the thruster were designed, manufactured and tested, aimed at gradual improvement of each next exemplar. In the current paper, the heat loads in new engine have been discussed. It has been shown that thermal equilibrium of the thruster is gained within the safety limits of the materials used. Extensive testing with both gases was performed to compare KLIMT’s thermal behaviour when supplied with krypton and xenon propellants.

  20. Investigation of thermal effects in through-silicon vias using scanning thermal microscopy.

    Science.gov (United States)

    Wielgoszewski, Grzegorz; Jóźwiak, Grzegorz; Babij, Michał; Baraniecki, Tomasz; Geer, Robert; Gotszalk, Teodor

    2014-11-01

    Results of quantitative investigations of copper through-silicon vias (TSVs) are presented. The experiments were performed using scanning thermal microscopy (SThM), enabling highly localized imaging of thermal contrast between the copper TSVs and the surrounding material. Both dc and ac active-mode SThM was used and differences between these variants are shown. SThM investigations of TSVs may provide information on copper quality in TSV, as well as may lead to quantitative investigation of thermal boundaries in micro- and nanoelectronic structures. A proposal for heat flow analysis in a TSV, which includes the influence of the boundary region between the TSV and the silicon substrate, is presented; estimation of contact resistance and boundary thermal conductance is also given. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Experimental and modeling study of forest fire effect on soil thermal conductivity

    Science.gov (United States)

    Kathleen M. Smits; Elizabeth Kirby; William J. Massman; Scott Baggett

    2016-01-01

    An understanding of soil thermal conductivity after a wildfire or controlled burn is important to land management and post-fire recovery efforts. Although soil thermal conductivity has been well studied for non-fire heated soils, comprehensive data that evaluate the long-term effect of extreme heating from a fire on the soil thermal conductivity are limited....

  2. NOUR. Daylighting and thermal effects of windows in desert houses

    Energy Technology Data Exchange (ETDEWEB)

    Ouahrani, Djamel

    1999-07-01

    This study is on a combined effect of window, the daylighting and the thermal effects, in desert houses. It is comprised of two complementary studies. In the introduction a historical review on the development of using daylight has been carried out in order to place the case study in a historical perspective. The first study is comprehensive and contains two main parts. In the first part a study was carried out on the people and history of the town of Ghardaia in Southern Algeria. This was done in order to understand the architectural form of that region. The second part is experimental and consists of two field studies carried out in Ghardaia. Their aim was to investigate the influence of daylight and temperature on the use of residential houses. This investigation included both traditional and 'modern' houses, the modern having relatively large windows similar to those of the northern part of Algeria, the traditional ones having small or no windows. The second study is also experimental consisting of computer parametric studies on window design from two standpoints, namely daylighting level and thermal effects of windows in desert houses. A typical traditional house is described as it was observed. Then the recorded light values are presented and commented upon. In the second part, three types of modern houses observed in the field studies are presented and compared to the traditional archetype. The comparison especially dwells on the relative effectiveness of the two systems of daylighting. In the third part, focusing on various issues of lighting, the results of interviews with the inhabitants are presented. The historical studies indicate that the process of housing development, in several respects, has reached a certain quality (social, technology, and adaptation to climate) appropriate to the local original context, but that development has slowed down. The results of the lighting study indicate that the use of more windows in modern houses

  3. Deposition stress effects on thermal barrier coating burner rig life

    Science.gov (United States)

    Watson, J. W.; Levine, S. R.

    1984-01-01

    A study of the effect of plasma spray processing parameters on the life of a two layer thermal barrier coating was conducted. The ceramic layer was plasma sprayed at plasma arc currents of 900 and 600 amps onto uncooled tubes, cooled tubes, and solid bars of Waspalloy in a lathe with 1 or 8 passes of the plasma gun. These processing changes affected the residual stress state of the coating. When the specimens were tested in a Mach 0.3 cyclic burner rig at 1130 deg C, a wide range of coating lives resulted. Processing factors which reduced the residual stress state in the coating, such as reduced plasma temperature and increased heat dissipation, significantly increased coating life.

  4. Thermal and viscous effects on sound waves: revised classical theory.

    Science.gov (United States)

    Davis, Anthony M J; Brenner, Howard

    2012-11-01

    In this paper the recently developed, bi-velocity model of fluid mechanics based on the principles of linear irreversible thermodynamics (LIT) is applied to sound propagation in gases taking account of first-order thermal and viscous dissipation effects. The results are compared and contrasted with the classical Navier-Stokes-Fourier results of Pierce for this same situation cited in his textbook. Comparisons are also made with the recent analyses of Dadzie and Reese, whose molecularly based sound propagation calculations furnish results virtually identical with the purely macroscopic LIT-based bi-velocity results below, as well as being well-supported by experimental data. Illustrative dissipative sound propagation examples involving application of the bi-velocity model to several elementary situations are also provided, showing the disjoint entropy mode and the additional, evanescent viscous mode.

  5. Radiation and thermal effects on cobalt retention by Mexican aluminosilicates

    Energy Technology Data Exchange (ETDEWEB)

    Davila-Rangel, J.I. [Departamento de Quimica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico 11801, D. F. (Mexico); Unidad Academica Centro Regional de Estudios Nucleares, Universidad Autonoma de Zacatecas, Cipres 10, Frac. La Penuela, Zacatecas, Zacatecas 98068 (Mexico); Facultad de Ciencias, Universidad Autonoma del Estado de Mexico, Instituto Literario No. 100 Col. Centro C. P. 50000, Toluca, Edo. de Mexico (Mexico); Solache-Rios, M. [Departamento de Quimica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico 11801, D. F. (Mexico)]. E-mail: msr@nuclear.inin.mx; Nunez-Monreal, J.E. [Unidad Academica de Ciencias Quimicas, Programa de Ingenieria Quimica, Universidad Autonoma de Zacatecas, Km. 0.5 Carr. a Cd. Cuauhtemoc., Guadalupe, Zacatecas 98600 (Mexico)

    2007-05-15

    Thermal and radiation effects on the leaching of cobalt from two cobalt exchanged zeolites and one clay were determined. The cobalt exchanged aluminosilicates were heated at different temperatures (500, 700, 900 and 1100 deg. C), and the materials were then treated with NaCl (1 and 5 M) and HNO{sub 3} (0.001 and 1 M) solutions to determine the leaching behavior of cobalt from the materials. Cobalt showed greater stability when the materials were heated at the highest temperature. The unheated samples and those heated at 1100 deg. C were gamma irradiated, and it was found that cobalt leaching from gamma irradiated aluminosilicates was higher than that for non-irradiated materials.

  6. Isotope Effect on the Thermal Conductivity of Graphene

    Directory of Open Access Journals (Sweden)

    Hengji Zhang

    2010-01-01

    Full Text Available The thermal conductivity (TC of isolated graphene with different concentrations of isotope (C13 is studied with equilibrium molecular dynamics method at 300 K. In the limit of pure C12 or C13 graphene, TC of graphene in zigzag and armchair directions are ~630 W/mK and ~1000W/mK, respectively. We find that the TC of graphene can be maximally reduced by ~80%, in both armchair and zigzag directions, when a random distribution of C12 and C13 is assumed at different doping concentrations. Therefore, our simulation results suggest an effective way to tune the TC of graphene without changing its atomic and electronic structure, thus yielding a promising application for nanoelectronics and thermoelectricity of graphene-based nano device.

  7. Determination of Thermal Conductivity of Silicate Matrix for Applications in Effective Media Theory

    Science.gov (United States)

    Fiala, Lukáš; Jerman, Miloš; Reiterman, Pavel; Černý, Robert

    2018-02-01

    Silicate materials have an irreplaceable role in the construction industry. They are mainly represented by cement-based- or lime-based materials, such as concrete, cement mortar, or lime plaster, and consist of three phases: the solid matrix and air and water present in the pores. Therefore, their effective thermal conductivity depends on thermal conductivities of the involved phases. Due to the time-consuming experimental determination of the effective thermal conductivity, its calculation by means of homogenization techniques presents a reasonable alternative. In the homogenization theory, both volumetric content and particular property of each phase need to be identified. For porous materials the most problematic part is to accurately identify thermal conductivity of the solid matrix. Due to the complex composition of silicate materials, the thermal conductivity of the matrix can be determined only approximately, based on the knowledge of thermal conductivities of its major compounds. In this paper, the thermal conductivity of silicate matrix is determined using the measurement of a sufficiently large set of experimental data. Cement pastes with different open porosities are prepared, dried, and their effective thermal conductivity is determined using a transient heat-pulse method. The thermal conductivity of the matrix is calculated by means of extrapolation of the effective thermal conductivity versus porosity functions to zero porosity. Its practical applicability is demonstrated by calculating the effective thermal conductivity of a three-phase silicate material and comparing it with experimental data.

  8. Evidence of Non-local Chemical, Thermal and Gravitational Effects

    Directory of Open Access Journals (Sweden)

    Hu H.

    2007-04-01

    Full Text Available Quantum entanglement is ubiquitous in the microscopic world and manifests itself macroscopically under some circumstances. But common belief is that it alone cannot be used to transmit information nor could it be used to produce macroscopic non- local effects. Yet we have recently found evidence of non-local effects of chemical substances on the brain produced through it. While our reported results are under independent verifications by other groups, we report here our experimental findings of non-local chemical, thermal and gravitational effects in simple physical systems such as reservoirs of water quantum-entangled with water being manipulated in a remote reservoir. With the aids of high-precision instruments, we have found that the pH value, temperature and gravity of water in the detecting reservoirs can be non-locally affected through manipulating water in the remote reservoir. In particular, the pH value changes in the same direction as that being manipulated; the temperature can change against that of local environment; and the gravity apparently can also change against local gravity. These non-local effects are all reproducible and can be used for non-local signalling and many other purposes. We suggest that they are mediated by quantum entanglement between nuclear and/or electron spins in treated water and discuss the implications of these results.

  9. Thermal Transport in Supported Graphene: Substrate Effects on Collective Excitations

    Science.gov (United States)

    France-Lanord, Arthur; Soukiassian, Patrick; Glattli, Christian; Wimmer, Erich

    2017-03-01

    A detailed computational analysis of thermal transport in supported graphene reveals the possibility of tuning its thermal conductivity by targeted chemical modifications of the substrate's surface. Based on classical molecular dynamics with an accurate charge-optimized bond-order force field and a time-domain normal-mode analysis, our approach allows us to distinguish collective from single-phonon excitations. The computations reveal a disproportional reduction of the thermal conductivity, due to the two different excitations, when graphene interacts with a substrate. Deposition of graphene on a bare silica surface leads to a dramatic reduction of the thermal conductivity and a change in the heat transport mechanism. Remarkably, partial hydroxylation of the silica surface almost doubles the thermal conductivity of the collective excitations. Thus, specific surface terminations allow for control of the thermal conductivity of graphene.

  10. The effect of the thermal inertia on the thermal transfer in building wall

    Science.gov (United States)

    Bellahcene, Lahcene; Cheknane, Ali; Bekkouche, SMA.; Sahel, Djemal

    2017-11-01

    In a hot and dry climate, the design and construction of buildings involve the adoption of combination between shape of building envelope and construction materials. The objective of this work is to study the thermal behavior of a multilayer wall submitted to varying climatic conditions. We have proposed four configurations of an element of an outer wall. A numerical simulation was used to understand the phenomenon of thermal inertia, especially its influence on the resulting temperatures. The study is based on the modeling of heat transfer in a 2D unsteady-state using a computational fluid dynamics (CFD) code. The comparison of numerical results was affected with an available experimental data and shows a satisfactory agreement. In addition, this work highlights the importance of the study of the thermal inertia of the wall in order to ensure a comfortable indoor climate of building located in hot and dry climate.

  11. Piezoelectric effect on the thermal conductivity of monolayer gallium nitride

    Science.gov (United States)

    Zhang, Jin

    2018-01-01

    Using molecular dynamics and density functional theory simulations, in this work, we find that the heat transport property of the monolayer gallium nitride (GaN) can be efficiently tailored by external electric field due to its unique piezoelectric characteristic. As the monolayer GaN possesses different piezoelectric properties in armchair and zigzag directions, different effects of the external electric field on thermal conductivity are observed when it is applied in the armchair and zigzag directions. Our further study reveals that due to the elastoelectric effect in the monolayer GaN, the external electric field changes the Young's modulus and therefore changes the phonon group velocity. Also, due to the inverse piezoelectric effect, the applied electric field induces in-plane stress in the monolayer GaN subject to a length constraint, which results in the change in the lattice anharmonicity and therefore affects the phonon mean free path. Furthermore, for relatively long GaN monolayers, the in-plane stress may trigger the buckling instability, which can significantly reduce the phonon mean free path.

  12. THERMAL INSULATION EFFECTS ON ENERGY EFFICIENCY OF BUILDING STRUCTURES

    OpenAIRE

    M. Cvetkovska; Knezevic, M.; Rogac, M.

    2012-01-01

    This paper presents the use of Finite Element Method for heat transfer analysis. Connections wall-beam-floor structures with different positions of the thermal insulation have been analyzed and conclusions about energy efficiency and energy loss are made. Keywords: heat transfer, numerical analysis, finite elements, thermal insulation, energy efficiency.

  13. Effect of organic modification on the thermal transformations of ...

    Indian Academy of Sciences (India)

    Abstract. X-ray diffraction (XRD) and thermal analysis techniques were used to study the thermal transforma- tions of raw (Maghnia bentonite) and modified bentonite (algae extract (ulvans) within clay). XRD data showed that the basal spacing (d001) was gradually decreased from ∼12.80 Å (6.90◦ (2θ)) at room temperature ...

  14. Effect of thermal processing methods on the proximate composition ...

    African Journals Online (AJOL)

    The nutritive value of raw and thermal processed castor oil seed (Ricinus communis) was investigated using the following parameters; proximate composition, gross energy, mineral constituents and ricin content. Three thermal processing methods; toasting, boiling and soaking-and-boiling were used in the processing of the ...

  15. Nonlinear dynamical effects on reaction rates in thermally fluctuating environments.

    Science.gov (United States)

    Kawai, Shinnosuke; Komatsuzaki, Tamiki

    2010-07-21

    A framework to calculate the rate constants of condensed phase chemical reactions of manybody systems is presented without relying on the concept of transition state. The theory is based on a framework we developed recently adopting a multidimensional underdamped Langevin equation in the region of a rank-one saddle. The theory provides a reaction coordinate expressed as an analytical nonlinear functional of the position coordinates and velocities of the system (solute), the friction constants, and the random force of the environment (solvent). Up to moderately high temperature, the sign of the reaction coordinate can determine the final destination of the reaction in a thermally fluctuating media, irrespective of what values the other (nonreactive) coordinates may take. In this paper, it is shown that the reaction probability is analytically derived as the probability of the reaction coordinate being positive, and that the integration with the Boltzmann distribution of the initial conditions leads to the exact reaction rate constant when the local equilibrium holds and the quantum effect is negligible. Because of analytical nature of the theory taking into account all nonlinear effects and their combination with fluctuation and dissipation, the theory naturally provides us with the firm mathematical foundation of the origin of the reactivity of the reaction in a fluctuating media.

  16. Effect of the Environmental Stimuli upon the Human Body in Winter Outdoor Thermal Environment

    Science.gov (United States)

    Kurazumi, Yoshihito; Kondo, Emi; Ishii, Jin; Sakoi, Tomonori; Fukagawa, Kenta; Bolashikov, Zhecho Dimitrov; Tsuchikawa, Tadahiro; Matsubara, Naoki; Horikoshi, Tetsumi

    2013-01-01

    In order to manage the outdoor thermal environment with regard to human health and the environmental impact of waste heat, quantitative evaluations are indispensable. It is necessary to use a thermal environment evaluation index. The purpose of this paper is to clarify the relationship between the psychological thermal responses of the human body and winter outdoor thermal environment variables. Subjective experiments were conducted in the winter outdoor environment. Environmental factors and human psychological responses were measured. The relationship between the psychological thermal responses of the human body and the outdoor thermal environment index ETFe (enhanced conduction-corrected modified effective temperature) in winter was shown. The variables which influence the thermal sensation vote of the human body are air temperature, long-wave thermal radiation and short-wave solar radiation. The variables that influence the thermal comfort vote of the human body are air temperature, humidity, short-wave solar radiation, long-wave thermal radiation, and heat conduction. Short-wave solar radiation, and heat conduction are among the winter outdoor thermal environment variables that affect psychological responses to heat. The use of thermal environment evaluation indices that comprise short-wave solar radiation and heat conduction in winter outdoor spaces is a valid approach. PMID:23861691

  17. Effect of the Environmental Stimuli upon the Human Body in Winter Outdoor Thermal Environment

    Directory of Open Access Journals (Sweden)

    Yoshihito Kurazumi

    2013-01-01

    Full Text Available In order to manage the outdoor thermal environment with regard to human health and the environmental impact of waste heat, quantitative evaluations are indispensable. It is necessary to use a thermal environment evaluation index. The purpose of this paper is to clarify the relationship between the psychological thermal responses of the human body and winter outdoor thermal environment variables. Subjective experiments were conducted in the winter outdoor environment. Environmental factors and human psychological responses were measured. The relationship between the psychological thermal responses of the human body and the outdoor thermal environment index ETFe (enhanced conduction-corrected modified effective temperature in winter was shown. The variables which influence the thermal sensation vote of the human body are air temperature, long-wave thermal radiation and short-wave solar radiation. The variables that influence the thermal comfort vote of the human body are air temperature, humidity, short-wave solar radiation, long-wave thermal radiation, and heat conduction. Short-wave solar radiation, and heat conduction are among the winter outdoor thermal environment variables that affect psychological responses to heat. The use of thermal environment evaluation indices that comprise short-wave solar radiation and heat conduction in winter outdoor spaces is a valid approach.

  18. Competition between the Thermal Gradient and the Bimorph Effect in Locally Heated MEMS Actuators

    DEFF Research Database (Denmark)

    Jeppesen, Claus; Mølhave, Kristian; Kristensen, Anders

    2009-01-01

    We have investigated the influence of thermal gradient effects in inhomogeneously heated MEMS/NEMS. The actuation perturbations caused by thermal gradients have been studied through static optothermal actuation experiments of a bi-material polymer based cantilever and supported by finite element...... modeling. As a result, bidirectional bending has been experimentally observed and interpreted as the competition between bimorph and thermal gradient effects. The competition has illustrated the importance of including the thermal gradient effect in the behavior analysis of bimorph driven MEMS/NEMS devices....

  19. Doppler broadening effect on collision cross section functions - Deconvolution of the thermal averaging

    Science.gov (United States)

    Bernstein, R. B.

    1973-01-01

    The surprising feature of the Doppler problem in threshold determination is the 'amplification effect' of the target's thermal energy spread. The small thermal energy spread of the target molecules results in a large dispersion in relative kinetic energy. The Doppler broadening effect in connection with thermal energy beam experiments is discussed, and a procedure is recommended for the deconvolution of molecular scattering cross-section functions whose dominant dependence upon relative velocity is approximately that of the standard low-energy form.

  20. Effective Thermal Conductivity of an Aluminum Foam + Water Two Phase System

    Science.gov (United States)

    Moskito, John

    1996-01-01

    This study examined the effect of volume fraction and pore size on the effective thermal conductivity of an aluminum foam and water system. Nine specimens of aluminum foam representing a matrix of three volume fractions (4-8% by vol.) and three pore sizes (2-4 mm) were tested with water to determine relationships to the effective thermal conductivity. It was determined that increases in volume fraction of the aluminum phase were correlated to increases in the effective thermal conductivity. It was not statistically possible to prove that changes in pore size of the aluminum foam correlated to changes in the effective thermal conductivity. However, interaction effects between the volume fraction and pore size of the foam were statistically significant. Ten theoretical models were selected from the published literature to compare against the experimental data. Models by Asaad, Hadley, and de Vries provided effective thermal conductivity predictions within a 95% confidence interval.

  1. Effect of surrogate aggregates on the thermal conductivity of concrete at ambient and elevated temperatures.

    Science.gov (United States)

    Yun, Tae Sup; Jeong, Yeon Jong; Youm, Kwang-Soo

    2014-01-01

    The accurate assessment of the thermal conductivity of concretes is an important part of building design in terms of thermal efficiency and thermal performance of materials at various temperatures. We present an experimental assessment of the thermal conductivity of five thermally insulated concrete specimens made using lightweight aggregates and glass bubbles in place of normal aggregates. Four different measurement methods are used to assess the reliability of the thermal data and to evaluate the effects of the various sensor types. The concrete specimens are also assessed at every 100 °C during heating to ~800 °C. Normal concrete is shown to have a thermal conductivity of ~2.25 W m(-1) K(-1). The surrogate aggregates effectively reduce the conductivity to ~1.25 W m(-1) K(-1) at room temperature. The aggregate size is shown not to affect thermal conduction: fine and coarse aggregates each lead to similar results. Surface contact methods of assessment tend to underestimate thermal conductivity, presumably owing to high thermal resistance between the transducers and the specimens. Thermogravimetric analysis shows that the stages of mass loss of the cement paste correspond to the evolution of thermal conductivity upon heating.

  2. Effect of Surrogate Aggregates on the Thermal Conductivity of Concrete at Ambient and Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Tae Sup Yun

    2014-01-01

    Full Text Available The accurate assessment of the thermal conductivity of concretes is an important part of building design in terms of thermal efficiency and thermal performance of materials at various temperatures. We present an experimental assessment of the thermal conductivity of five thermally insulated concrete specimens made using lightweight aggregates and glass bubbles in place of normal aggregates. Four different measurement methods are used to assess the reliability of the thermal data and to evaluate the effects of the various sensor types. The concrete specimens are also assessed at every 100°C during heating to ~800°C. Normal concrete is shown to have a thermal conductivity of ~2.25 W m−1 K−1. The surrogate aggregates effectively reduce the conductivity to ~1.25 W m−1 K−1 at room temperature. The aggregate size is shown not to affect thermal conduction: fine and coarse aggregates each lead to similar results. Surface contact methods of assessment tend to underestimate thermal conductivity, presumably owing to high thermal resistance between the transducers and the specimens. Thermogravimetric analysis shows that the stages of mass loss of the cement paste correspond to the evolution of thermal conductivity upon heating.

  3. effect of pre effect of pre-ageing thermal conditions on the corrosion ...

    African Journals Online (AJOL)

    eobe

    Keywords: Al-Si-Mg alloy, thermal ageing, polarization, eutectics, interdendritic spacing. 1. INTRODUCTION. INTRODUCTION. INTRODUCTION. Corrosion of aluminium alloys lead to impairment of its operation and progressive weakening of that structure. The consequences of corrosion are many, and its effects on safety, ...

  4. Aging Effects and Estimating Degradation Mechanisms of Thermally Upgraded Paper in Mineral Oil

    Science.gov (United States)

    Miyagi, Katsunori; Oe, Etsuo; Yamagata, Naoki

    The life of a transformer is limited to the deterioration of its solid insulation. Winding conductors and other solid insulation materials in oil-immersed transformers have been insulated using cellulose products. For many years, manufacturers have met the needs of special applications by designing transformers using thermally upgraded materials to achieve lighter weight, higher power density and increased life. Recently, the effect of thermally upgraded insulation on diagnostic techniques such as gas-in oil analysis, and their indication of insulation degradation have been reviewed. This paper describes evaluations of the thermal degradation characteristics and decomposition reactions in mineral transformer oil of amine-impregnated thermally upgraded paper insulation. The thermal resistance of the thermally upgraded paper is evaluated by comparison with Kraft paper insulation. Further, aging degradation mechanisms of decompositional degradation of the thermally upgraded paper due to aging in mineral transformer oil are proposed.

  5. The InSight Mars Lander and Its Effect on the Subsurface Thermal Environment

    Science.gov (United States)

    Siegler, Matthew A.; Smrekar, Suzanne E.; Grott, Matthias; Piqueux, Sylvain; Mueller, Nils; Williams, Jean-Pierre; Plesa, Ana-Catalina; Spohn, Tilman

    2017-10-01

    The 2018 InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) Mission has the mission goal of providing insitu data for the first measurement of the geothermal heat flow of Mars. The Heat Flow and Physical Properties Package (HP3) will take thermal conductivity and thermal gradient measurements to approximately 5 m depth. By necessity, this measurement will be made within a few meters of the lander. This means that thermal perturbations from the lander will modify local surface and subsurface temperature measurements. For HP3's sensitive thermal gradient measurements, this spacecraft influence will be important to model and parameterize. Here we present a basic 3D model of thermal effects of the lander on its surroundings. Though lander perturbations significantly alter subsurface temperatures, a successful thermal gradient measurement will be possible in all thermal conditions by proper (>3 m depth) placement of the heat flow probe.

  6. Thermal shock resistance behavior of a functionally graded ceramic: Effects of finite cooling rate

    Directory of Open Access Journals (Sweden)

    Zhihe Jin

    2014-01-01

    Full Text Available This work presents a semi-analytical model to explore the effects of cooling rate on the thermal shock resistance behavior of a functionally graded ceramic (FGC plate with a periodic array of edge cracks. The FGC is assumed to be a thermally heterogeneous material with constant elastic modulus and Poisson's ratio. The cooling rate applied at the FGC surface is modeled using a linear ramp function. An integral equation method and a closed form asymptotic temperature solution are employed to compute the thermal stress intensity factor (TSIF. The thermal shock residual strength and critical thermal shock of the FGC plate are obtained using the SIF criterion. Thermal shock simulations for an Al2O3/Si3N4 FGC indicate that a finite cooling rate leads to a significantly higher critical thermal shock than that under the sudden cooling condition. The residual strength, however, is relatively insensitive to the cooling rate.

  7. Cosmological phases of the string thermal effective potential

    Energy Technology Data Exchange (ETDEWEB)

    Bourliot, F., E-mail: Francois.Bourliot@cpht.polytechnique.f [Centre de Physique Theorique, Ecole Polytechnique, F-91128 Palaiseau cedex (France); Estes, J., E-mail: John.Estes@cpth.polytechnique.f [Centre de Physique Theorique, Ecole Polytechnique, F-91128 Palaiseau cedex (France); Kounnas, C., E-mail: Costas.Kounnas@lpt.ens.f [Laboratoire de Physique Theorique, Ecole Normale Superieure, 24 rue Lhomond, F-75231 Paris cedex 05 (France); Partouche, H., E-mail: Herve.Partouche@cpht.polytechnique.f [Centre de Physique Theorique, Ecole Polytechnique, F-91128 Palaiseau cedex (France)

    2010-05-01

    In a superstring framework, the free energy density F can be determined unambiguously at the full string level once supersymmetry is spontaneously broken via geometrical fluxes. We show explicitly that only the moduli associated to the supersymmetry breaking may give relevant contributions. All other spectator moduli mu{sub I} give exponentially suppressed contributions for relatively small (as compared to the string scale) temperature T and supersymmetry breaking scale M. More concisely, for mu{sub I}>T and M, F takes the form F(T,M;mu{sub I})=F(T,M)+O[exp(-(mu{sub I})/T ),exp(-(mu{sub I})/M )]. We study the cosmological regime where T and M are below the Hagedorn temperature scale T{sub H}. In this regime, F remains finite for any values of the spectator moduli mu{sub I}. We investigate extensively the case of one spectator modulus mu{sub d} corresponding to R{sub d}, the radius-modulus field of an internal compactified dimension. We show that its thermal effective potential V(T,M;mu)=F(T,M;mu) admits five phases, each of which can be described by a distinct but different effective field theory. For late cosmological times, the Universe is attracted to a 'Radiation-like evolution' with M(t)propor toT(t)propor to1/a(t)propor tot{sup -2/d}. The spectator modulus mu(t) is stabilized either to the stringy enhanced symmetry point where R{sub d}=1, or fixed at an arbitrary constant mu{sub 0}>T,M. For arbitrary boundary conditions at some initial time, t{sub E}, mu(t) may pass through more than one effective field theory phase before its final attraction.

  8. The effects of deep water cycling on planetary thermal evolution

    Science.gov (United States)

    Sandu, Constantin; Lenardic, Adrian; McGovern, Patrick

    2011-12-01

    We use a parameterized convection model to investigate the effects of deep water cycling on the thermal evolution of an Earth-like planet. The model incorporates two water reservoirs, a surface and an interior mantle reservoir. Exchange between the two is calculated using a mantle convection parameterization that allows for temperature- and water-dependent mantle viscosity together with internally self-consistent degassing and regassing parameterizations. The balance between degassing and regassing depends on the average spreading rate of tectonic plates, the amount of water partitioned into melt, the thickness of a mantle melt zone, and of a hydrated layer at the top of subducting plates. Degassing scales with melt zone thickness such that an early period of extensive melting would create a drier and more viscous mantle, shifting the solidus line in a direction that would reduce the melt zone thickness and the rate of mantle heat loss. Coupling a hydrated zone thickness-dependent regassing factor to the model, to mimic water delivery to the mantle via a serpentinized layer, allows for the potential of a reversing point where the overall water flow direction switches from degassing to regassing as the mantle cools. The water effect on viscosity creates a negative feedback that tends to regulate the final amount of water in the mantle so it is not strongly dependent on the initial amount of planetary water. The final amount of water in the surface reservoir is then determined by this feedback effect together with the initial water budget of the entire planet. This implies that if the initial water budget of a planet can be estimated, from planetary formation models, then the volume of surface water can be used to estimate the volume of water in the mantle of an Earth-like planet. Applying this methodology to the Earth leads to predictions for water concentration in the Earth's mantle that are in line with geochemical and petrological constraints.

  9. Parental Effect of Long Acclimatization on Thermal Tolerance of Juvenile Sea Cucumber Apostichopus japonicus.

    Directory of Open Access Journals (Sweden)

    Qing-Lin Wang

    Full Text Available To evaluate the thermal resistance of marine invertebrates to elevated temperatures under scenarios of future climate change, it is crucial to understand parental effect of long acclimatization on thermal tolerance of offspring. To test whether there is parental effect of long acclimatization, adult sea cucumbers (Apostichopus japonicus from the same broodstock were transplanted southward and acclimatized at high temperature in field mesocosms. Four groups of juvenile sea cucumbers whose parents experienced different durations of high temperature acclimatization were established. Upper thermal limits, oxygen consumption and levels of heat shock protein mRNA of juveniles was determined to compare thermal tolerance of individuals from different groups. Juvenile sea cucumbers whose parents experienced high temperature could acquire high thermal resistance. With the increase of parental exposure duration to high temperature, offspring became less sensitive to high temperature, as indicated by higher upper thermal limits (LT50, less seasonal variations of oxygen consumption, and stable oxygen consumption rates between chronic and acute thermal stress. The relatively high levels of constitutive expression of heat-shock proteins should contribute to the high thermal tolerance. Together, these results indicated that the existence of a parental effect of long acclimatization would increase thermal tolerance of juveniles and change the thermal sensitivity of sea cucumber to future climate change.

  10. A Study of the Effects of Altitude on Thermal Ice Protection System Performance

    Science.gov (United States)

    Addy, Gene; Oleskiw, Myron; Broeren, Andy P.; Orchard, David

    2013-01-01

    Thermal ice protection systems use heat energy to prevent a dangerous buildup of ice on an aircraft. As aircraft become more efficient, less heat energy is available to operate a thermal ice protections system. This requires that thermal ice protection systems be designed to more exacting standards so as to more efficiently prevent a dangerous ice buildup without adversely affecting aircraft safety. While the effects of altitude have always beeing taked into account in the design of thermal ice protection systems, a better understanding of these effects is needed so as to enable more exact design, testing, and evaluation of these systems.

  11. Investigation of the Effective Thermal Conductivity in Containment Wall of OPR1000

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Hyung Gyun [Pohang University, Pohang (Korea, Republic of); Lee, Jong Hwi; Kang, Hie Chan [Kunsan National University, Gunsan (Korea, Republic of)

    2016-05-15

    Many computational codes used for analyzing pressure of containment was developed such as CAP (Containment Analysis Package). These computational codes consider concrete conductivity instead of thermal conductivity of containment wall which have special geometry as heat sink. For precise analysis, effective thermal conductivity of containment wall has to be measured in individual NPPs. Thermal properties of concrete such as thermal conductivity have been investigated as function of chemical composition and temperature. Generally, containment of OPR1000 is constructed by Prestressed (PS) concrete-a composite material. Containment wall of OPR1000 is made up of steel liner, tendon, rebar and concrete as shown in Figure 1. Role of steel liner protects release of radioactive materials so called leak tightness. The effective thermal conductivity of containment wall in OPR1000 is analyzed by numerical tool (CFD) and compared with thermal conductivity models in composite solids. The effective thermal conductivity of containment wall of OPR1000 is investigated by numerical analysis (CFD). The thermal conductivity of reinforced concrete is 18.6% higher than that of concrete only. Several models were compared with CFD results. Rayleigh-Parallel liner model agrees well with CFD results. Experiment results will be compared with CFD result and models. CFD result was calculated in low steel volume fraction (0.0809) than that of OPR1000 (0.1043). The effective thermal conductivity in OPR1000 has slightly higher than CFD result because of different volume fraction.

  12. Effect of Material Composition and Environmental Condition on Thermal Characteristics of Conductive Asphalt Concrete.

    Science.gov (United States)

    Pan, Pan; Wu, Shaopeng; Hu, Xiaodi; Liu, Gang; Li, Bo

    2017-02-23

    Conductive asphalt concrete with high thermal conductivity has been proposed to improve the solar energy collection and snow melting efficiencies of asphalt solar collector (ASC). This paper aims to provide some insight into choosing the basic materials for preparation of conductive asphalt concrete, as well as determining the evolution of thermal characteristics affected by environmental factors. The thermal properties of conductive asphalt concrete were studied by the Thermal Constants Analyzer. Experimental results showed that aggregate and conductive filler have a significant effect on the thermal properties of asphalt concrete, while the effect of asphalt binder was not evident due to its low proportion. Utilization of mineral aggregate and conductive filler with higher thermal conductivity is an efficient method to prepare conductive asphalt concrete. Moreover, change in thermal properties of asphalt concrete under different temperature and moisture conditions should be taken into account to determine the actual thermal properties of asphalt concrete. There was no noticeable difference in thermal properties of asphalt concrete before and after aging. Furthermore, freezing-thawing cycles strongly affect the thermal properties of conductive asphalt concrete, due to volume expansion and bonding degradation.

  13. Effect of Material Composition and Environmental Condition on Thermal Characteristics of Conductive Asphalt Concrete

    Directory of Open Access Journals (Sweden)

    Pan Pan

    2017-02-01

    Full Text Available Conductive asphalt concrete with high thermal conductivity has been proposed to improve the solar energy collection and snow melting efficiencies of asphalt solar collector (ASC. This paper aims to provide some insight into choosing the basic materials for preparation of conductive asphalt concrete, as well as determining the evolution of thermal characteristics affected by environmental factors. The thermal properties of conductive asphalt concrete were studied by the Thermal Constants Analyzer. Experimental results showed that aggregate and conductive filler have a significant effect on the thermal properties of asphalt concrete, while the effect of asphalt binder was not evident due to its low proportion. Utilization of mineral aggregate and conductive filler with higher thermal conductivity is an efficient method to prepare conductive asphalt concrete. Moreover, change in thermal properties of asphalt concrete under different temperature and moisture conditions should be taken into account to determine the actual thermal properties of asphalt concrete. There was no noticeable difference in thermal properties of asphalt concrete before and after aging. Furthermore, freezing–thawing cycles strongly affect the thermal properties of conductive asphalt concrete, due to volume expansion and bonding degradation.

  14. Effect of particle size on the thermal conductivity of nanofluids containing metallic nanoparticles

    National Research Council Canada - National Science Library

    Warrier, Pramod; Teja, Amyn

    2011-01-01

    .... Although literature data could be correlated well using the model, the effect of the size of the particles on the effective thermal conductivity of the nanofluid could not be elucidated from these data...

  15. Effect of highly reflective roofing sheet on building thermal loads for a school in Osaka

    Directory of Open Access Journals (Sweden)

    Yuan Jihui

    2017-01-01

    Full Text Available Currently, urban heat island (UHI phenomenon and building energy consumptions are becoming serious. Strategies to mitigate UHI and reduce building energy consumptions are implemented worldwide. In Japan, as an effective means of mitigating UHI and saving energy of buildings, highly reflective (HR and green roofs are increasingly used. In order to evaluate the effect of roofs with high reflection and thermal insulation on the energy conservation of buildings, we investigated the roof solar reflectivity of the subject school in Osaka, in which the HR roofing sheet was installed on the roof from 2010. Thermal loads, including cooling and heating loads of the top floor of school, were calculated using the thermal load calculation software, New HASP/ACLD-β. Comparing the thermal loads after HR roofing sheet installation to previous, the annual thermal load decreased about 25 MJ/m2-year and the cooling load decreased about 112 MJ/m2-year. However, the heating load increased about 87 MJ/m2-year in winter. To minimize the annual thermal load, thermal insulation of the roof was also considered be used together with HR roofing sheet in this study. The results showed that the combination of HR roofing sheet and high thermal insulation is more effective to reduce the annual thermal load.

  16. Effects of basal-plane thermal conductivity and interface thermal conductance on the hot spot temperature in graphene electronic devices

    Science.gov (United States)

    Choi, David; Poudel, Nirakar; Cronin, Stephen B.; Shi, Li

    2017-02-01

    Electrostatic force microscopy and scanning thermal microscopy are employed to investigate the electric transport and localized heating around defects introduced during transfer of graphene grown by chemical vapor deposition to an oxidized Si substrate. Numerical and analytical models are developed to explain the results based on the reported basal-plane thermal conductivity, κ, and interfacial thermal conductance, G, of graphene and to investigate their effects on the peak temperature. Irrespective of the κ values, increasing G beyond 4 × 107 W m-2 K-1 can reduce the peak temperature effectively for graphene devices made on sub-10 nm thick gate dielectric, but not for the measured device made on 300-nm-thick oxide dielectric, which yields a cross-plane thermal conductance (Gox) much smaller than the typical G of graphene. In contrast, for typical G values reported for graphene, increasing κ from 300 W m-1 K-1 toward 3000 W m-1 K-1 is effective in reducing the hot spot temperature for the 300-nm-thick oxide devices but not for the sub-10 nm gate dielectric case, because the heat spreading length (l) can be appreciably increased relative to the micron-scale localized heat generation spot size (r0) only when the oxide layer is sufficiently thick. As such, enhancement of κ increases the vertical heat transfer area above the gate dielectric only for the thick oxide case. In all cases considered, the hot spot temperature is sensitive to varying G and κ only when the G/Gox ratio and r0/l ratio are below about 5, respectively.

  17. Effects of high thermal neutron fluences on Type 6061 aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Weeks, J.R.; Czajkowski, C.J. (Brookhaven National Lab., Upton, NY (United States)); Farrell, K. (Oak Ridge National Lab., TN (United States))

    1992-01-01

    The control rod drive follower tubes of the High Flux Beam Reactor are contructed from precipitation-hardened 6061-T6 aluminum alloy and they operate in the high thermal neutron flux regions of the core. It is shown that large thermal neutron fluences up to {approximately}4 {times} 10{sup 23} n/cm{sup 2} at 333K cause large increases in tensile strength and relatively modest decreases in tensile elongation while significantly reducing the notch impact toughness at room temperature. These changes are attributed to the development of a fine distribution of precipitates of amorphous silicon of which about 8% is produced radiogenically. A proposed role of thermal-to-fast flux ratio is discussed.

  18. Effects of high thermal neutron fluences on Type 6061 aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Weeks, J.R.; Czajkowski, C.J. [Brookhaven National Lab., Upton, NY (United States); Farrell, K. [Oak Ridge National Lab., TN (United States)

    1992-09-01

    The control rod drive follower tubes of the High Flux Beam Reactor are contructed from precipitation-hardened 6061-T6 aluminum alloy and they operate in the high thermal neutron flux regions of the core. It is shown that large thermal neutron fluences up to {approximately}4 {times} 10{sup 23} n/cm{sup 2} at 333K cause large increases in tensile strength and relatively modest decreases in tensile elongation while significantly reducing the notch impact toughness at room temperature. These changes are attributed to the development of a fine distribution of precipitates of amorphous silicon of which about 8% is produced radiogenically. A proposed role of thermal-to-fast flux ratio is discussed.

  19. The effect of Y2O3 addition on thermal shock behavior of magnesium aluminate spinel

    Directory of Open Access Journals (Sweden)

    Pošarac Milica

    2009-01-01

    Full Text Available The effect of yttria additive on the thermal shock behavior of magnesium aluminate spinel has been investigated. As a starting material we used spinel (MgAl2O4 obtained by the modified glycine nitrate procedure (MGNP. Sintered products were characterized in terms of phase analysis, densities, thermal shock, monitoring the damaged surface area in the refractory specimen during thermal shock and ultrasonic determination of the Dynamic Young modulus of elasticity. It was found that a new phase between yttria and alumina is formed, which improved thermal shock properties of the spinel refractories. Also densification of samples is enhanced by yttria addition.

  20. Spectral phonon scattering effects on the thermal conductivity of nano-grained barium titanate

    Science.gov (United States)

    Donovan, Brian F.; Foley, Brian M.; Ihlefeld, Jon F.; Maria, Jon-Paul; Hopkins, Patrick E.

    2014-08-01

    We study the effect of grain size on thermal conductivity of thin film barium titanate over temperatures ranging from 200 to 500 K. We show that the thermal conductivity of Barium Titanate (BaTiO3) decreases with decreasing grain size as a result of increased phonon scattering from grain boundaries. We analyze our results with a model for thermal conductivity that incorporates a spectrum of mean free paths in BaTiO3. In contrast to the common gray mean free path assumption, our findings suggest that the thermal conductivity of complex oxide perovskites is driven by a spectrum of phonons with varying mean free paths.

  1. Effects of thermal drying on phosphorus availability from iron-precipitated sewage sludge

    DEFF Research Database (Denmark)

    Lemming, Camilla; Scheutz, Charlotte; Bruun, Sander

    2017-01-01

    Thermal drying of sewage sludge implies sanitation and improves practical handling options of the sludge prior to land application. However, it may also affect its value as a fertilizer. The objective of this study was to assess whether thermal drying of sewage sludge, as well as drying temperature...... experiments, thermal drying reduced P availability, as shown by 37 and 23% lower DGT and WEP values, respectively, and a 16% lower P uptake by barley in the pot experiment. The specific drying temperature did not appear to have much effect. Overall, our results suggest that thermal drying of iron...

  2. Thermal Hall Effect in a Phonon-Glass Ba3 CuSb2 O9

    Science.gov (United States)

    Sugii, K.; Shimozawa, M.; Watanabe, D.; Suzuki, Y.; Halim, M.; Kimata, M.; Matsumoto, Y.; Nakatsuji, S.; Yamashita, M.

    2017-04-01

    A distinct thermal Hall signal is observed in a quantum spin liquid candidate Ba3 CuSb2 O9 . The transverse thermal conductivity shows a power-law temperature dependence below 50 K, where a spin gap opens. We suggest that because of the very low longitudinal thermal conductivity and the thermal Hall signals, a phonon Hall effect is induced by strong phonon scattering of orphan Cu2 + spins formed in the random domains of the Cu2 + -Sb5 + dumbbells in Ba3 CuSb2 O9 .

  3. Effects of ageing and moisture content on thermal properties of ...

    African Journals Online (AJOL)

    The mean thermal conductivity ranged from 0.4770 to 0.5654, 0.4804 to 0.5530 and 0.4302 to 0.6102 W/mK at these ages respectively. The thermal diffusivity also ranged from 1.588 to 2.426, 1.614 to 0.1972 and 1.610 to 2.020m2/s while the specific heat capacity ranged from 2.3626 to 3.1495, 2.4900 to 3.7538 and 3.4222 ...

  4. Effect of tuber skin on the thermal properties of whole tubers of potato and sweet potato

    Science.gov (United States)

    Oluwo, A. A.; Khan, R. M.; Salami, M. J. E.

    2013-12-01

    Temperature-dependent thermal coefficients of mathematical models of the postharvest storage process play an important role in determining the models accuracy. Thermal properties of tubers under storage available in literature are generally of those in semi processed form (skinless) such as those having undergone peeling, dicing and cutting actions. This study investigates the effect of tuber skin on the thermal properties of whole tubers of potato and sweet potato. A direct approach was used to measure the tubers' density and thermal conductivity and thermal diffusivity by the transient heat transfer method. Indirect approach was used to measure the tubers' specific heat. Experimental data were used to develop empirical models of the thermal coefficients as a function of temperature. Results of the study should find great use in the modeling of potato and sweet potato storage process.

  5. Effect of thermal dissipation by adding graphene materials to surface coating of LED lighting module.

    Science.gov (United States)

    Kim, S; Jeong, J Y; Han, S H; Kim, J H; Kwon, K T; Hwang, M K; Kim, I T; Cho, G S

    2013-05-01

    The effect of thermal dissipation by adding graphene nano-platelets to two different commercially available thermal dissipation coatings (ceramic coating and powder coating) was studied. Steady state temperatures of each points of LED modules was monitored in a closed system, with an integral photo detection sphere where there is no external air flow. Having eliminated the contributions of thermal conduction and air flow convection, the module with a conventional heat dissipation coatings showed 8-16% enhancement of thermal dissipation compared to that of non-coated LED module. The addition of graphene is shown to have about 3% additional enhancement. By analyzing thermal resistance of each component of the LED module, the improved thermal conductivity of the graphene added coatings contributes to the enhancement of slight improvement with heat dissipation.

  6. Effect of hydrophobic nano-silica on the thermal insulation of fibrous silica compacts

    Directory of Open Access Journals (Sweden)

    Tseng-Wen Lian

    2017-06-01

    Full Text Available The particle’s surface property plays an important role on controlling the thermal insulation performance of fibrous silica compacts. In the present study, the effect of addition of hydrophobic silica on the thermal conductivity of the fibrous silica compacts is investigated. The measurement was conducted using laser flash method and differential scanning calorimeter (DSC method. The thermal conductivity of fibrous silica compacts is only 0.042 W/m K. The addition of 5% hydrophobic silica further reduces the thermal conductivity of fibrous silica compacts to 0.033 W/m K. The thermal conductivity reaches a constant value with higher hydrophobic silica content. The flexural strength decreases with the increase of hydrophobic silica content. A compromise between the thermal insulation and strength is needed. The performance of fibrous silica compacts shows strong dependence on the surface structure of glass fibers.

  7. Absence of the Thermal Hall Effect in Anomalous Nernst and Spin Seebeck Effects.

    Science.gov (United States)

    Chen, Yi-Jia; Huang, Ssu-Yen

    2016-12-09

    The anomalous Nernst effect (ANE) and the spin Seebeck effect (SSE) in spin caloritronics are two of the most important mechanisms to manipulate the spin-polarized current and pure spin current by thermal excitation. While the ANE in ferromagnetic metals and the SSE in magnetic insulators have been extensively studied, a recent theoretical work suggests that the signals from the thermal Hall effect (THE) have field dependences indistinguishable from, and may even overwhelm, those of the ANE and SSE. Therefore, it is vital to investigate the contribution of the THE in the ANE and SSE. In this work, we systematically study the THE in a ferromagnetic metal, Permalloy (Py), and magnetic insulator, an yttrium iron garnet (YIG), by using different Seebeck coefficients between electrodes and contact wires. Our results demonstrate that the contribution of the THE by the thermal couple effect in the Py and YIG is negligibly small if one includes the thickness dependence of the Seebeck coefficient. Thus, the spin-polarized current in the ANE and the pure spin current in the SSE remain indispensable for exploring spin caloritronics phenomena.

  8. Assessment of effective thermal conductivity in U–Mo metallic fuels with distributed gas bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Shenyang; Casella, Andrew M.; Lavender, Curt A.; Senor, David J.; Burkes, Douglas E.

    2015-07-15

    This work presents a numerical method to assess the relative impact of various microstructural features including grain sizes, nanometer scale intragranular gas bubbles, and larger intergranular gas bubbles in irradiated U–Mo metallic fuels on the effective thermal conductivity. A phase-field model was employed to construct a three-dimensional polycrystalline U–Mo fuel alloy with a given crystal morphology and gas bubble microstructures. An effective thermal conductivity “concept” was taken to capture the effect of polycrystalline structures and gas bubble microstructures with significant size differences on the thermal conductivity. The thermal conductivity of inhomogeneous materials was calculated by solving the heat transport equation. The obtained results are in reasonably good agreement with experimental measurements made on irradiated U–Mo fuel samples containing similar microstructural features. The developed method can be used to predict the thermal conductivity degradation in operating nuclear fuels if the evolution of microstructures is known during operation of the fuel.

  9. Thermal Impedance Model of High Power IGBT Modules Considering Heat Coupling Effects

    DEFF Research Database (Denmark)

    Bahman, Amir Sajjad; Ma, Ke; Blaabjerg, Frede

    2014-01-01

    Thermal loading of Insulated Gate Bipolar Transistor (IGBT) modules is important for the reliability performance of power electronic systems, thus the thermal information of critical points inside module like junction temperature must be accurately modeled and predicted. Usually in the existing...... thermal models, only the self-heating effects of the chips are taken into account, while the thermal coupling effects among chips are less considered. This could result in inaccurate temperature estimation, especially in the high power IGBT modules where the chips are allocated closely to each other...... with large amount of heat generated. In this paper, both the self-heating and heat-coupling effects in the of IGBT module are investigated based on Finite Element Method (FEM) simulation, a new thermal impedance model is thereby proposed to better describe the temperature distribution inside IGBT modules...

  10. The effect of different transitional spaces on thermal comfort and energy consumption of residential buildings

    NARCIS (Netherlands)

    Taleghani, M.; Tenpierik, M.J.; Van den Dobbelsteen, A.A.J.F.

    2012-01-01

    Purpose- This paper focuses on the effect of courtyards, atria and sunspaces on indoor thermal comfort and energy consumption for heating and cooling. One of the most important purposes is to understand if certain transitional spaces can reduce the energy consumption of and improve thermal comfort

  11. Effect of urea additive on the thermal decomposition kinetics of flame retardant greige cotton nonwoven fabric

    Science.gov (United States)

    Sunghyun Nam; Brian D. Condon; Robert H. White; Qi Zhao; Fei Yao; Michael Santiago Cintrón

    2012-01-01

    Urea is well known to have a synergistic action with phosphorus-based flame retardants (FRs) in enhancing the FR performance of cellulosic materials, but the effect of urea on the thermal decomposition kinetics has not been thoroughly studied. In this study, the activation energy (Ea) for the thermal decomposition of greige...

  12. Electrochemical study of the thermal treatment effects on Cusub(x)S thin films

    Energy Technology Data Exchange (ETDEWEB)

    Duo, R.; Fatas, E.; Arjona, F.; Camarero, E.G.

    1983-03-01

    The effects of thermal treatments on the stoichiometry and photovoltaic properties of Cusub(x)S thin films have been studied. It has been observed that the evaporation of a thin copper films on Cusub(x)S, followed by thermal treatment in vacuum, improves the Cusub(x)S/CdS heterojunctions due to a rire in the stoichiometry and fill factor.

  13. On the Effective Thermal Conductivity of Frost Considering Mass Diffusion and Eddy Convection

    Science.gov (United States)

    Kandula, Max

    2010-01-01

    A physical model for the effective thermal conductivity of water frost is proposed for application to the full range of frost density. The proposed model builds on the Zehner-Schlunder one-dimensional formulation for porous media appropriate for solid-to-fluid thermal conductivity ratios less than about 1000. By superposing the effects of mass diffusion and eddy convection on stagnant conduction in the fluid, the total effective thermal conductivity of frost is shown to be satisfactorily described. It is shown that the effects of vapor diffusion and eddy convection on the frost conductivity are of the same order. The results also point out that idealization of the frost structure by cylindrical inclusions offers a better representation of the effective conductivity of frost as compared to spherical inclusions. Satisfactory agreement between the theory and the measurements for the effective thermal conductivity of frost is demonstrated for a wide range of frost density and frost temperature.

  14. Metallic nanowire networks: effects of thermal annealing on electrical resistance

    Science.gov (United States)

    Langley, D. P.; Lagrange, M.; Giusti, G.; Jiménez, C.; Bréchet, Y.; Nguyen, N. D.; Bellet, D.

    2014-10-01

    Metallic nanowire networks have huge potential in devices requiring transparent electrodes. This article describes how the electrical resistance of metal nanowire networks evolve under thermal annealing. Understanding the behavior of such films is crucial for the optimization of transparent electrodes which find many applications. An in-depth investigation of silver nanowire networks under different annealing conditions provides a case study demonstrating that several mechanisms, namely local sintering and desorption of organic residues, are responsible for the reduction of the systems electrical resistance. Optimization of the annealing led to specimens with transmittance of 90% (at 550 nm) and sheet resistance of 9.5 Ω sq-1. Quantized steps in resistance were observed and a model is proposed which provides good agreement with the experimental results. In terms of thermal behavior, we demonstrate that there is a maximum thermal budget that these electrodes can tolerate due to spheroidization of the nanowires. This budget is determined by two main factors: the thermal loading and the wire diameter. This result enables the fabrication and optimization of transparent metal nanowire electrodes for solar cells, organic electronics and flexible displays.

  15. Effects of nanoscale size dependent parameters on lattice thermal ...

    Indian Academy of Sciences (India)

    Throughout the method of trial and error, using the MATHCAD. 12 program, the values of P,Nimp and γ were adjusted such that the best fit for calculated lattice thermal conductivity to the experimental curves were obtained as shown in figure 3. The diameter dependence of the fitting parameters Nimp,P and γ (L, T ) and γ ...

  16. Effects of reduction time on the structural, electrical and thermal ...

    Indian Academy of Sciences (India)

    catalyst support in direct methanol fuel cell. Therefore, in this paper, the RGO nanosheets were prepared via highly efficient chemical reduction reaction of exfoliated GO nanosheets using sodium oxalate (Na2C2O4) as the reduc- ing agent. Extensive characterizations have been conducted in terms of structural, thermal ...

  17. Effect of urban albedo surfaces on thermal comfort | Mansouri ...

    African Journals Online (AJOL)

    They have addressed this issue in order to identify the main causes that generate the warming of urban areas and therefore contribute to the degradation of the exterior and interior thermal comfort of the inhabitants. It turns out that the reflectivity of materials known as the albedo, plays a leading role in this degradation.

  18. Thermal effects on cognition: a new quantitative synthesis.

    Science.gov (United States)

    López-Sánchez, José Ignacio; Hancock, P A

    2017-07-05

    There is little doubt that increases in thermal load beyond the thermo-neutral state prove progressively stressful to all living organisms. Increasing temperatures across the globe represent in some locales, and especially for outdoors workers, a significant source of such chronic load increase. However, increases in thermal load affect cognition as well as physical work activities. Such human cognition has perennially been viewed as the primary conduit through which to solve many of the iatrogenic challenges we now face. Yet, thermal stress degrades the power to think. Here, we advance and refine the isothermal description of such cognitive decrements, founded upon a synthesis of extant empirical evidence. We report a series of mathematical functions which describe task-specific patterns of performance deterioration, linking such degrees of decrement to the time/temperature conditions in which they occur. Further, we provide a simple, free software tool to support such calculations so that adverse thermal loads can be monitored, assessed and (where possible) mitigated to preserve healthy cognitive functioning.

  19. Effective thermal conductivity of real two-phase systems using ...

    Indian Academy of Sciences (India)

    An effort is made to correlate it in terms of the ratio of thermal conductivities of the constituents and the physical porosity. Theoretical expression so obtained has been tested on a large number of samples cited in the literature and found that the values predicted are quite close to the experimental results. Comparison of our ...

  20. Effective thermal conductivity of real two-phase systems using ...

    Indian Academy of Sciences (India)

    Unknown

    non-uniform shape of the particles and non-linear flow of heat flux lines in real systems, incorporating an empirical correction factor in place of physical porosity modifies an expression for ETC. An effort is made to correlate it in terms of the ratio of thermal conductivities of the constituents and the physical porosity. Theo-.

  1. Thermal Expansion and Aging Effects in Neuromorphic Signal Processor

    NARCIS (Netherlands)

    Zjajo, A.; van Leuken, T.G.R.M.

    2016-01-01

    In this paper, we propose an efficient methodology based on a real-time estimator and predictor-corrector scheme for accurate thermal expansion profile and aging evaluation of a neuromorphic signal processor circuit components. As the experimental results indicate, for comparable mesh size, the

  2. Thermal boundary effects on a GT liner structure

    NARCIS (Netherlands)

    Salvatore, M.; Laget, H.; Vanderhaegen, E.; Altunlu, A.C.; Tufano, S.; Daumantas, Ciplys

    2012-01-01

    GT combustor liners are subjected to mechanical and thermal loads that damage the structure and reduce their operational life. Among those, the thermo-acoustic instabilities develop, generating pressure oscillations because of the interaction between heat release, acoustic waves and structure

  3. The effect of Acacia Karroo supplementation and thermal ...

    African Journals Online (AJOL)

    Bathesh

    2012-08-14

    Aug 14, 2012 ... thermal preparation on consumer sensory scores of meat from indigenous Xhosa lop-eared goat breed. 18 castrated four-month-old ... (Muchenje et al., 2008b; 2009a, b), age (Simela, 2005), ageing, fatness and ..... fresh Sulla (Hedysarum coronarium L.) with or without polyethylene glycol or concentrate.

  4. The Effect of Thermal Processing on Apple Puree's Structuring Ability

    Directory of Open Access Journals (Sweden)

    G.E. Polischuk

    2013-07-01

    Full Text Available The influence of temperature and duration of heat processing on the structural ability of apple puree was studied. It was proved, that apple puree reveals the thixotropic and rheopexic character when its structure is restored, depending on the conditions of thermal processing.

  5. Determination of thermally induced effects and design guidelines of optomechanical accelerometers

    Science.gov (United States)

    Lu, Qianbo; Bai, Jian; Wang, Kaiwei; Jiao, Xufen; Han, Dandan; Chen, Peiwen; Liu, Dong; Yang, Yongying; Yang, Guoguang

    2017-11-01

    Thermal effects, including thermally induced deformation and warm up time, are ubiquitous problems for sensors, especially for inertial measurement units such as accelerometers. Optomechanical accelerometers, which contain light sources that can be regarded as heat sources, involve a different thermal phenomenon in terms of their specific optical readout, and the phenomenon has not been investigated systematically. This paper proposes a model to evaluate the temperature difference, rise time and thermally induced deformation of optomechanical accelerometers, and then constructs design guidelines which can diminish these thermal effects without compromising other mechanical performances, based on the analysis of the interplay of thermal and mechanical performances. In the model, the irradiation of the micromachined structure of a laser source is considered a dominant factor. The experimental data obtained using a prototype of an optomechanical accelerometer approximately confirm the validity of the model for the rise time and response tendency. Moreover, design guidelines that adopt suspensions with a flat cross-section and a short length are demonstrated with reference to the analysis. The guidelines can reduce the thermally induced deformation and rise time or achieve higher mechanical performances with similar thermal effects, which paves the way for the design of temperature-tolerant and robust, high-performance devices.

  6. Effective strategies for development of thermal heavy oil field facilities

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Ken; Lehnert-Thiel, Gunter [IMV Projects (Canada)

    2011-07-01

    In thermal heavy oil, a significant part of the capital has to be invested in field facilities and therefore strategies have to be implemented to optimize these costs. Field facilities consist of pipelines, earthworks and production pads whose purpose is to connect an oilsands reservoir to a central processing facility. This paper, presented by IMV Projects, a leading company in the thermal heavy oil field, highlights strategies to manage field facility lifecycle cost. Upfront planning should be done and the development of field facilities should be thought of as a long term infrastructure program rather than a stand-alone project. In addition, templates should be developed to save money and repeatability should be implemented to obtain a better prediction of the program's costs. The strategies presented herein allow major savings over the program's life by implementing an improved schedule and allowing refinements all along the program's course.

  7. Thermal Effect of Ceramic Nanofiller Aluminium Nitride on Polyethylene Properties

    Directory of Open Access Journals (Sweden)

    Omer Bin Sohail

    2012-01-01

    Full Text Available Ethylene polymerization was done to form polyethylene nano-composite with nanoaluminum nitride using zirconocene catalysts. Results show that the catalytic activity is maximum at a filler loading of 15 mg nanoaluminum nitride. Differential scanning calorimeter (DSC and X-ray diffraction (XRD results show that percentage crystallinity was also marginally higher at this amount of filler. Thermal behavior of polyethylene nanocomposites (0, 15, 30, and 45 mg was studied by DSC and thermal gravimetric analyzer (TGA. Morphology of the component with 15 mg aluminium nitride is more fibrous as compared to 0 mg aluminium nitride and higher filler loading as shown by SEM images. In order to understand combustibility behavior, tests were performed on microcalorimeter. Its results showed decrease in combustibility in polyethylene nanocomposites as the filler loading increases.

  8. Energy Consumption of Insulated Material Using Thermal Effect Analysis

    OpenAIRE

    Fadzil M. A.; Norliyati M. A.; Hilmi M. A.; Ridzuan A. R.; Wan Ibrahim M. H.; Assrul R. Z.

    2017-01-01

    Wall is one of the structures elements that resist direct heat from the atmosphere. Modification on several structures is relevance to reduce filtrate thermal movement on wall. Insulation material seems to be suitable to be implemented since its purpose meets the heat resistance requirement. Insulation material applied as to generate positive impact in energy saving through reduction in total building energy consumption. Fiberglass is one of the insulation materials that can be used to insula...

  9. Effect of Some Thermal Processing Methods on the Caffeine ...

    African Journals Online (AJOL)

    Fresh kola nuts (Cola nitida) were thermally processed (blanched, boiled and roasted) for different periods of time (5, 10, 15 and 20 minutes respectively) at different temperatures (65, 75, 85 and 95oC). Boiling was done at 80oC while roasting was at 108.5oC, and steam blanching duration was 5, 7.5, 15 and 20 seconds ...

  10. Effects of Porosity and Thermal Treatment on Hydration of Mushrooms

    OpenAIRE

    Paudel, Ekaraj; Boom, R.M.; Sman, van der, R.G.M.

    2016-01-01

    In this study, hydration of mushroom as a porous food material has been studied considering their biphasic character. It consists of a solid phase that consists of intertwined hyphae and having cell walls with a swellable polymeric matrix and a pore phase made up by the space in between the hyphae. We have investigated the hydration of mushrooms as a function of initial porosity and thermal treatment. Variation in porosity is induced by the natural variation in the growth of mushroom. Porosit...

  11. Thermal effect of climate change on groundwater-fed ecosystems

    Science.gov (United States)

    Burns, Erick; Zhu, Yonghui; Zhan, Hongbin; Manga, Michael; Williams, Colin F.; Ingebritsen, Steven E.; Dunham, Jason

    2017-01-01

    Groundwater temperature changes will lag surface temperature changes from a changing climate. Steady state solutions of the heat-transport equations are used to identify key processes that control the long-term thermal response of springs and other groundwater discharge to climate change, in particular changes in (1) groundwater recharge rate and temperature and (2) land-surface temperature transmitted through the vadose zone. Transient solutions are developed to estimate the time required for new thermal signals to arrive at ecosystems. The solution is applied to the volcanic Medicine Lake highlands, California, USA, and associated springs complexes that host groundwater-dependent ecosystems. In this system, upper basin groundwater temperatures are strongly affected only by recharge conditions. However, as the vadose zone thins away from the highlands, changes in the average annual land-surface temperature also influence groundwater temperatures. Transient response to temperature change depends on both the conductive time scale and the rate at which recharge delivers heat. Most of the thermal response of groundwater at high elevations will occur within 20 years of a shift in recharge temperatures, but the large lower elevation springs will respond more slowly, with about half of the conductive response occurring within the first 20 years and about half of the advective response to higher recharge temperatures occurring in approximately 60 years.

  12. Thermal effect of climate change on groundwater-fed ecosystems

    Science.gov (United States)

    Burns, Erick R.; Zhu, Yonghui; Zhan, Hongbin; Manga, Michael; Williams, Colin F.; Ingebritsen, Steven E.; Dunham, Jason B.

    2017-04-01

    Groundwater temperature changes will lag surface temperature changes from a changing climate. Steady state solutions of the heat-transport equations are used to identify key processes that control the long-term thermal response of springs and other groundwater discharge to climate change, in particular changes in (1) groundwater recharge rate and temperature and (2) land-surface temperature transmitted through the vadose zone. Transient solutions are developed to estimate the time required for new thermal signals to arrive at ecosystems. The solution is applied to the volcanic Medicine Lake highlands, California, USA, and associated springs complexes that host groundwater-dependent ecosystems. In this system, upper basin groundwater temperatures are strongly affected only by recharge conditions. However, as the vadose zone thins away from the highlands, changes in the average annual land-surface temperature also influence groundwater temperatures. Transient response to temperature change depends on both the conductive time scale and the rate at which recharge delivers heat. Most of the thermal response of groundwater at high elevations will occur within 20 years of a shift in recharge temperatures, but the large lower elevation springs will respond more slowly, with about half of the conductive response occurring within the first 20 years and about half of the advective response to higher recharge temperatures occurring in approximately 60 years.

  13. Experimental study of thermal effects on the mechanical behaviour of a clay

    Science.gov (United States)

    Cekerevac, Cane; Laloui, Lyesse

    2004-03-01

    The paper presents the results of an experimental study of thermal effects on the mechanical behaviour of a saturated clay. The study was performed on CM clay (Kaolin) using a temperature-controlled triaxial apparatus. Applied temperatures were between 22 and 90°C. A comprehensive experimental program was carried out, including: (i) triaxial shear tests at ambient and high temperatures for different initial overconsolidation ratios; (ii) consolidation tests at ambient and high temperatures; and (iii) drained thermal heating for different initial overconsolidation ratios. The obtained results provide observations concerning a wide scope of the thermo-mechanical behaviour of clays. Test results obtained at 90°C were compared with tests performed at ambient temperature. Based on these comparisons, thermal effects on a variety of features of behaviour are presented and discussed. Focus is made on: (i) induced thermal volume change during drained heating; (ii) experimental evidence of temperature influence on preconsolidation pressure and on compressibility index; (iii) thermal effects on shear strength and critical state; and (iv) thermal effects on elastic modulus. Thermal yielding is discussed and yield limit evolution with temperature is presented. The directions of the induced plastic strains are also discussed. Several remarks on the difference in the mechanical behaviour at ambient and high temperatures conclude the paper. Copyright

  14. Cellulose nanowhiskers from coconut husk fibers: effect of preparation conditions on their thermal and morphological behavior

    Science.gov (United States)

    Cellulose nanowhiskers were prepared by sulfuric acid hydrolysis from coconut husk fibers which had previously been submitted to a delignification process. The effects of preparation conditions on the thermal and morphological behavior of the nanocrystals were investigated. Cellulose nanowhisker sus...

  15. Dynamical thermal effects in InGaAsP microtubes at telecom wavelengths.

    Science.gov (United States)

    Tian, Zhaobing; Bianucci, Pablo; Roche, Philip J R; Dastjerdi, M Hadi Tavakoli; Mi, Zetian; Poole, Philip J; Kirk, Andrew G; Plant, David V

    2012-07-01

    We report on the observation of a dynamical thermal effect in InGaAsP microtubes at telecom wavelengths. The microtubes are fabricated by releasing a strained semiconductor bilayer and are picked up by abruptly tapered optical fibers for subsequent coupling with adiabatically tapered optical fibers. As a result of absorption by InAs quantum dots embedded in the tube structure, these microtubes show dynamical thermal effects at wavelengths around 1525 nm and 1578 nm, while they are passive at longer wavelengths near 1634 nm. The photon absorption induced thermal effect is visualized by generating a pair of microbottles. The dynamical thermal effect can be avoided or exploited for passive or active applications by utilizing appropriate resonance wavelengths.

  16. Effective thermal conductivity method for predicting spent nuclear fuel cladding temperatures in a dry fill gas

    Energy Technology Data Exchange (ETDEWEB)

    Bahney, Robert

    1997-12-19

    This paper summarizes the development of a reliable methodology for the prediction of peak spent nuclear fuel cladding temperature within the waste disposal package. The effective thermal conductivity method replaces other older methodologies.

  17. Sterilization effect of atmospheric pressure non-thermal air plasma on dental instruments

    National Research Council Canada - National Science Library

    Sung, Su-Jin; Huh, Jung-Bo; Yun, Mi-Jung; Chang, Brian Myung W; Jeong, Chang-Mo; Jeon, Young-Chan

    2013-01-01

    .... To develop a dental sterilizer which can sterilize most materials, such as metals, rubbers, and plastics, the sterilization effect of an atmospheric pressure non-thermal air plasma device was evaluated...

  18. Thermal effects on aquatic organisms. Annotated bibliography of the 1975 literature

    Energy Technology Data Exchange (ETDEWEB)

    Coutant, C.C.; Talmage, S.S.; Carrier, R.F.; Collier, B.N.; Dailey, N.S. (comps.)

    1976-10-01

    Abstracts are presented of 716 papers published during 1975 concerning thermal effects on aquatic organisms. Indexes are included for author, subject category, geographic location, toxon, title, and keywords. (CH)

  19. Effects of heating with radiofrequency power on myocardial impulse conduction: is radiofrequency ablation exclusively thermally mediated?

    NARCIS (Netherlands)

    Simmers, T. A.; de Bakker, J. M.; Wittkampf, F. H.; Hauer, R. N.

    1996-01-01

    Although it is generally accepted that radiofrequency (RF) ablation causes exclusively thermally mediated effects, it has never been proved. In a previous report, temperatures required to induce conduction block in superfused canine epicardial ventricular myocardium were identified by exposure to

  20. Registry Effect on the Thermal Conductivity of Few-Layer Graphene

    OpenAIRE

    Jiang, Jin-Wu

    2014-01-01

    We perform molecular dynamics simulations to study the registry effect on the thermal conductivity of few-layer graphene. The interlayer interaction is described by either the Lennard-Jones potential or the registry-dependent potential. Our calculations show that the thermal conductivity in few-layer graphene from both potentials are close to each other, i.e the registry effect is essentially not important. It is because the thermal transport in few-layer graphene is mainly limited by the int...

  1. Mathematical Modeling and Numerical Analysis of Thermal Distribution in Arch Dams considering Solar Radiation Effect

    Science.gov (United States)

    Mirzabozorg, H.; Hariri-Ardebili, M. A.; Shirkhan, M.; Seyed-Kolbadi, S. M.

    2014-01-01

    The effect of solar radiation on thermal distribution in thin high arch dams is investigated. The differential equation governing thermal behavior of mass concrete in three-dimensional space is solved applying appropriate boundary conditions. Solar radiation is implemented considering the dam face direction relative to the sun, the slop relative to horizon, the region cloud cover, and the surrounding topography. It has been observed that solar radiation changes the surface temperature drastically and leads to nonuniform temperature distribution. Solar radiation effects should be considered in thermal transient analysis of thin arch dams. PMID:24695817

  2. Analysis of thermal effects in endoscopic nanocarriers-based photodynamic therapy applied to esophageal diseases

    Science.gov (United States)

    Salas-García, I.; Fanjul-Vélez, F.; Ortega-Quijano, N.; Wilfert, O.; Hudcova, L.; Poliak, J.; Barcik, P.; Arce-Diego, J. L.

    2014-02-01

    In this work we propose a predictive model that allows the study of thermal effects produced when the optical radiation interacts with an esophageal or stomach disease with gold nanoparticles embedded. The model takes into account light distribution in the tumor tissue by means of a Monte Carlo method. Mie theory is used to obtain the gold nanoparticles optical properties and the thermal model employed is based on the bio-heat equation. The complete model was applied to two types of tumoral tissue (squamous cell carcinoma located in the esophagus and adenocarcinoma in the stomach) in order to study the thermal effects induced by the inclusion of gold nanoparticles.

  3. Effects of torsion on the thermal conductivity of multi-layer graphene

    Science.gov (United States)

    Si, Chao; Lu, Gui; Cao, Bing-Yang; Wang, Xiao-Dong; Fan, Zhen; Feng, Zhi-Hai

    2017-05-01

    This work employs the equilibrium molecular dynamics method to study the effects of torsion on the thermal conductivity of multi-layer graphene. Thermal conductivities of twisted 10-layer 433.91 × 99.68 Å2 graphene with torsion angles of 0°, 11.25°, 22.5°, 33.75°, 45°, 67.5°, 90°, 112.5°, and 135° are calculated. The corresponding radial distribution functions and nearest atomic distances are calculated to reveal the effects of torsion on lattice structures. The spectral energy density (SED) method is utilized to analyze the phonon transport properties. It is very interesting that the thermal conductivity of multi-layer graphene decreases slightly at first and then increases with the increasing torsion angle, and the valley is located at θG = 22.5° with the lowest thermal conductivity of 4692.40 W m-1 K-1. The torsion effect can be considered as a combination of the compression effect and the dislocation effect. Further SED analysis confirms that the effect of dislocation on thermal conductivities can be negligible, while the compression effect decreases the phonon lifetimes of flexural out-of-plane acoustic (ZA) branches and increases the ZA group velocities and the phonon specific heat. The decrease becomes dominated when the torsion angle is small, whereas the increase becomes more and more dominated when the torsion angle becomes larger, which are responsible for the reported variation of thermal conductivities.

  4. Measurement of the effective thermal cross section of {sup 134}Cs by triple neutron capture reaction

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Shoji; Harada, Hideo; Katoh, Toshio [Power Reactor and Nuclear Fuel Development Corp., Tokai, Ibaraki (Japan). Tokai Works; Hatsukawa, Yuichi; Shinohara, Nobuo; Hata, Kentaro; Kobayashi, Katsutoshi; Motoishi, Shoji; Tanase, Masakazu

    1998-03-01

    The effective thermal cross section ({sigma}{sub eff}) of the {sup 134}Cs(n,{gamma}){sup 135}Cs reaction was measured by the activation method and the {gamma}-ray spectroscopic method in order to obtain fundamental data for research on the transmutation of nuclear wastes. The effective thermal cross section of the reaction {sup 134}Cs(n,{gamma}){sup 135}Cs was found to be 140.6{+-}8.5 barns. (author)

  5. Non-adiabatic effects within a single thermally averaged potential energy surface: thermal expansion and reaction rates of small molecules.

    Science.gov (United States)

    Alonso, J L; Castro, A; Clemente-Gallardo, J; Echenique, P; Mazo, J J; Polo, V; Rubio, A; Zueco, D

    2012-12-14

    At non-zero temperature and when a system has low-lying excited electronic states, the ground-state Born-Oppenheimer approximation breaks down and the low-lying electronic states are involved in any chemical process. In this work, we use a temperature-dependent effective potential for the nuclei which can accommodate the influence of an arbitrary number of electronic states in a simple way, while at the same time producing the correct Boltzmann equilibrium distribution for the electronic part. With the help of this effective potential, we show that thermally activated low-lying electronic states can have a significant effect in molecular properties for which electronic excitations are oftentimes ignored. We study the thermal expansion of the Manganese dimer, Mn(2), where we find that the average bond length experiences a change larger than the present experimental accuracy upon the inclusion of the excited states into the picture. We also show that, when these states are taken into account, reaction-rate constants are modified. In particular, we study the opening of the ozone molecule, O(3), and show that in this case the rate is modified as much as a 20% with respect to the ground-state Born-Oppenheimer prediction.

  6. Effect of Moisture Content on Thermal Properties of Porous Building Materials

    Science.gov (United States)

    Kočí, Václav; Vejmelková, Eva; Čáchová, Monika; Koňáková, Dana; Keppert, Martin; Maděra, Jiří; Černý, Robert

    2017-02-01

    The thermal conductivity and specific heat capacity of characteristic types of porous building materials are determined in the whole range of moisture content from dry to fully water-saturated state. A transient pulse technique is used in the experiments, in order to avoid the influence of moisture transport on measured data. The investigated specimens include cement composites, ceramics, plasters, and thermal insulation boards. The effect of moisture-induced changes in thermal conductivity and specific heat capacity on the energy performance of selected building envelopes containing the studied materials is then analyzed using computational modeling of coupled heat and moisture transport. The results show an increased moisture content as a substantial negative factor affecting both thermal properties of materials and energy balance of envelopes, which underlines the necessity to use moisture-dependent thermal parameters of building materials in energy-related calculations.

  7. Multiscale Modeling of Carbon/Phenolic Composite Thermal Protection Materials: Atomistic to Effective Properties

    Science.gov (United States)

    Arnold, Steven M.; Murthy, Pappu L.; Bednarcyk, Brett A.; Lawson, John W.; Monk, Joshua D.; Bauschlicher, Charles W., Jr.

    2016-01-01

    Next generation ablative thermal protection systems are expected to consist of 3D woven composite architectures. It is well known that composites can be tailored to achieve desired mechanical and thermal properties in various directions and thus can be made fit-for-purpose if the proper combination of constituent materials and microstructures can be realized. In the present work, the first, multiscale, atomistically-informed, computational analysis of mechanical and thermal properties of a present day - Carbon/Phenolic composite Thermal Protection System (TPS) material is conducted. Model results are compared to measured in-plane and out-of-plane mechanical and thermal properties to validate the computational approach. Results indicate that given sufficient microstructural fidelity, along with lowerscale, constituent properties derived from molecular dynamics simulations, accurate composite level (effective) thermo-elastic properties can be obtained. This suggests that next generation TPS properties can be accurately estimated via atomistically informed multiscale analysis.

  8. Mechanistic evaluation of the effect of thermal-treating on Eudragit RS matrices.

    Science.gov (United States)

    Azarmi, Shirzad; Ghaffari, Fatemeh; Löbenberg, Raimar; Nokhodchi, Ali

    2005-01-01

    Thermal treatment of acrylic matrices was recently introduced as a tool for prolonging the release of drug. Thermal treatment at temperatures above the T(g) of the polymer can decrease drug release rate. In this research we studied the mechanism of the effect of thermal treatment on Eudragit RS matrices. Indomethacin was used as model drug. The results showed that polymer chain movement and redistribution of the polymer in the tablet matrix structure after thermal-treating is the possible mechanism of drug release prolongation. The melting and resolidification of the polymer, due to the thermal treatment has apparently resulted in a redistribution of the polymer throughout the matrix and a change in the porosity of the tablet. FTIR results did not show any drug-polymer interaction due to heat-treatment. DSC and PXD studies ruled out the occurrence of solid solution and polymorphic change of the drug.

  9. Identifying possible non-thermal effects of radio frequency energy on inactivating food microorganisms.

    Science.gov (United States)

    Kou, Xiaoxi; Li, Rui; Hou, Lixia; Zhang, Lihui; Wang, Shaojin

    2018-02-01

    Radio frequency (RF) heating has been successfully used for inactivating microorganisms in agricultural and food products. Athermal (non-thermal) effects of RF energy on microorganisms have been frequently proposed in the literature, resulting in difficulties for developing effective thermal treatment protocols. The purpose of this study was to identify if the athermal inactivation of microorganisms existed during RF treatments. Escherichia coli and Staphylococcus aureus in apple juice and mashed potato were exposed to both RF and conventional thermal energies to compare their inactivation populations. A thermal death time (TDT) heating block system was used as conventional thermal energy source to simulate the same heating treatment conditions, involving heating temperature, heating rate and uniformity, of a RF treatment at a frequency of 27.12 MHz. Results showed that a similar and uniform temperature distribution in tested samples was achieved in both heating systems, so that the central sample temperature could be used as representative one for evaluating thermal inactivation of microorganisms. The survival patterns of two target microorganisms in two food samples were similar both for RF and heating block treatments since their absolute difference of survival populations was  0.05) in inactivating bacteria between the RF and the heating block treatments at each set of temperatures. The solid temperature and microbial inactivation data demonstrated that only thermal effect of RF energy at 27.12 MHz was observed on inactivating microorganisms in foods. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. The effect of functionalized silver nanoparticles over the thermal conductivity of base fluids

    Directory of Open Access Journals (Sweden)

    Merve Seyhan

    2017-04-01

    Full Text Available Thermal conductivities of nanofluids are expected to be higher than common heat transfer fluids. The use of metal nanoparticles has not been intensely investigated for heat transfer applications due to lack of stability. Here we present an experimental study on the effect of silver nanoparticles (Ag NPs which are stabilized with surfactants, on the thermal conductivity of water, ethylene glycol and hexane. Hydrophilic Ag NPs were synthesized in aqueous medium with using gum arabic as surfactant and oleic acid/oleylamine were used to stabilize Ag NPs in the organic phase. The enhancement up to 10 per cent in effective thermal conductivity of hexane and ethylene glycol was achieved with addition of Ag NPs at considerably low concentrations (i.e. 2 and 1 per cent, by weight, for hexane and ethylene glycol respectively. However, almost 10 per cent of deterioration was recorded at effective thermal conductivity of water when Ag NPs were added at 1 per cent (by wt. Considerable amount of Gum Arabic in the medium is shown to be the major contributor to this fall, causing lowering of thermal conductivity of water. Same particles performed much better in ethylene glycol where the stabilizer does not lower the thermal conductivity of the base fluid. Also thermal conductivity of nanofluids was found to be temperature independent except water based Ag nanofluids above a threshold concentration. This temperature dependency is suggested to be due to inhibition of hydrogen bonding among water molecules in the presence of high amounts of gum arabic.

  11. The effect of functionalized silver nanoparticles over the thermal conductivity of base fluids

    Science.gov (United States)

    Seyhan, Merve; Altan, Cem Levent; Gurten, Berna; Bucak, Seyda

    2017-04-01

    Thermal conductivities of nanofluids are expected to be higher than common heat transfer fluids. The use of metal nanoparticles has not been intensely investigated for heat transfer applications due to lack of stability. Here we present an experimental study on the effect of silver nanoparticles (Ag NPs) which are stabilized with surfactants, on the thermal conductivity of water, ethylene glycol and hexane. Hydrophilic Ag NPs were synthesized in aqueous medium with using gum arabic as surfactant and oleic acid/oleylamine were used to stabilize Ag NPs in the organic phase. The enhancement up to 10 per cent in effective thermal conductivity of hexane and ethylene glycol was achieved with addition of Ag NPs at considerably low concentrations (i.e. 2 and 1 per cent, by weight, for hexane and ethylene glycol respectively). However, almost 10 per cent of deterioration was recorded at effective thermal conductivity of water when Ag NPs were added at 1 per cent (by wt). Considerable amount of Gum Arabic in the medium is shown to be the major contributor to this fall, causing lowering of thermal conductivity of water. Same particles performed much better in ethylene glycol where the stabilizer does not lower the thermal conductivity of the base fluid. Also thermal conductivity of nanofluids was found to be temperature independent except water based Ag nanofluids above a threshold concentration. This temperature dependency is suggested to be due to inhibition of hydrogen bonding among water molecules in the presence of high amounts of gum arabic.

  12. Effect of amantadine on oxymorphone-induced thermal antinociception in cats.

    Science.gov (United States)

    Siao, K T; Pypendop, B H; Escobar, A; Stanley, S D; Ilkiw, J E

    2012-04-01

    This study examined the effect of amantadine, an N-methyl-d-aspartate receptor antagonist, on the thermal antinociceptive effect of oxymorphone in cats. Six adult healthy cats were used. After baseline thermal threshold determinations, oxymorphone was administered intravenously to maintain plasma oxymorphone concentrations of 10, 20, 50, 100, 200, and 400 ng/mL. In addition, amantadine, or an equivalent volume of saline, was administered intravenously to maintain a plasma amantadine concentration of 1100 ng/mL. Thermal threshold and plasma oxymorphone and amantadine concentrations were determined at each target plasma oxymorphone concentration. Effect maximum models were fitted to the oxymorphone concentration-thermal threshold data, after transformation in % maximum response. Oxymorphone increased skin temperature, thermal threshold, and thermal excursion (i.e., the difference between thermal threshold and skin temperature) in a concentration-dependent manner. No significant difference was found between the amantadine and saline treatments. Mean ± SE oxymorphone EC(50) were 14.2 ± 1.2 and 24.2 ± 7.4 ng/mL in the amantadine and saline groups, respectively. These values were not significantly different. Large differences in oxymorphone EC(50) in the saline and amantadine treatment groups were observed in two cats. These results suggest that amantadine may decrease the antinociceptive dose of oxymorphone in some, but not all, cats. © 2011 Blackwell Publishing Ltd.

  13. Auto-correcting for atmospherical effects in thermal hyperspectral measurements

    Science.gov (United States)

    Timmermans, Joris; Buitrago-Acevedo, Maria; Verhoef, Wout

    2017-04-01

    Correct estimation of soil and vegetation thermal emissivity's has been of huge importance in remote sensing studies. Field measurements of the leaf/soil and canopy emissivity can lead to estimations of water content. Consequently several studies have been performed with the objective of identifying the spectral behavior of the emissivity. However such measurements provide additional challenges before any retrieval can successfully be performed. While in laboratory the influence of the atmospheric conditions can be controlled in field experiments this cannot be done. In most cases such atmospheric correction however requires detailed knowledge of the atmospheric constituents at the time of the measurements. The objective of this research was to create an auto-atmospherically correct thermal hyperspectral emissivity measurements for retrieving canopy water content. For this hyperspectral thermal measurements were obtained during ESAs REFLEX campaign in 2012 using a MIDAC FTIR radiometer. MODTRAN simulations were used to construct a simple quadratic radiative transfer model that couples atmospheric transmissivities to the different gas constituents. This model was afterwards used to estimate the concentrations of H20 (g) and CO2 (g). The radiative measurements were afterwards corrected for these gas absorptions. Finally a temperature emissivity separation was applied to estimate the emissivities of the different land surface components. Gas concentrations were validated against measurements of a LICOR 7500 taken in parallel to the MIDAC measurements. It is observed that in general the relative errors are around 25% of the LICOR measurements, which are in the same range as the instrumental errors of the eddy-covariance system (15-30%). The correction of the absorption features proved however more difficult and resulted in overestimations of the correction-terms; 1) because spectral collocation of the simulations with the observations proved troublesome, and 2 because

  14. Effects of rim structure formation on the thermal conductivity of UO{sub 2} pellets

    Energy Technology Data Exchange (ETDEWEB)

    Amaya, Masaki; Hirai, Mutsumi [Global Nuclear Fuel - Japan Co., Ltd., Oarai, Ibaraki (Japan); Kaino, Masaru; Hattori, Toshiitsu [Tokyo Electric Power Company, Yokohama, Kanagawa (Japan)

    2002-11-01

    Thermal diffusivities of UO{sub 2} pellets irradiated in a test reactor were measured by using a laser flash method. The maximum burnups of the samples were about 85 GWd/t and some of the samples contained rim structures. Thermal diffusivities of irradiated decreased compared with those of unirradiated and simulated soluble fission products-doped UO{sub 2} pellets. Hysteresis phenomena in the thermal diffusivity of irradiated fuel, which had been reported before, were not clearly observed in UO{sub 2} pellets in which the rim structures had formed. The thermal conductivities for irradiated UO{sub 2} pellets were evaluated from measured thermal diffusivities, specific heat capacities of unirradiated UO{sub 2} pellets and measured sample densities. The thermal conductivities of irradiated UO{sub 2} were compared to those of unirradiated UO{sub 2} pellets. The relative thermal conductivities were normalized to those of 96.5% TD (Theoretical Density). These normalized thermal conductivities of irradiated UO{sub 2} pellets in which significant rim structures had formed tended to be slightly higher than those of irradiated UO{sub 2} pellets in which no rim structure had formed. This may be caused by an effect of recrystallization in rim structures. (author)

  15. Crystallite Size Effect on Thermal Conductive Properties of Nonwoven Nanocellulose Sheets.

    Science.gov (United States)

    Uetani, Kojiro; Okada, Takumi; Oyama, Hideko T

    2015-07-13

    The thermal conductive properties, including the thermal diffusivity and resultant thermal conductivity, of nonwoven nanocellulose sheets were investigated by separately measuring the thermal diffusivity of the sheets in the in-plane and thickness directions with a periodic heating method. The cross-sectional area (or width) of the cellulose crystallites was the main determinant of the thermal conductive properties. Thus, the results strongly indicate that there is a crystallite size effect on phonon conduction within the nanocellulose sheets. The results also indicated that there is a large interfacial thermal resistance between the nanocellulose surfaces. The phonon propagation velocity (i.e., the sound velocity) within the nanocellulose sheets was estimated to be ∼800 m/s based on the relationship between the thermal diffusivities and crystallite widths. The resulting in-plane thermal conductivity of the tunicate nanocellulose sheet was calculated to be ∼2.5 W/mK, markedly higher than other plastic films available for flexible electronic devices.

  16. Effects of thermal cycling on aluminum metallization of power diodes

    DEFF Research Database (Denmark)

    Brincker, Mads; Pedersen, Kristian Bonderup; Kristensen, Peter Kjær

    2015-01-01

    Reconstruction of aluminum metallization on top of power electronic chips is a well-known wear out phenomenon under power cycling conditions. However, the origins of reconstruction are still under discussion. In the current study, a method for carrying out passive thermal cycling of power diodes...... is controlled and the device is not subjected to a current load the observed degradation of metallization and corresponding increase of resistance is purely induced by thermo-mechanical stress. A correlation between number of cycles, micro-structural evolution, and sheet resistance is found and conclusions...

  17. Thermal effects of dams in the Willamette River basin, Oregon

    Science.gov (United States)

    Rounds, Stewart A.

    2010-01-01

    where the annual maximum temperature typically occurred in September or October. Without-dam temperatures also tended to have more daily variation than with-dam temperatures. Examination of the without-dam temperature estimates indicated that dam sites could be grouped according to the amount of streamflow derived from high-elevation, spring-fed, and snowmelt-driven areas high in the Cascade Mountains (Cougar, Big Cliff/Detroit, River Mill, and Hills Creek Dams: Group A), as opposed to flow primarily derived from lower-elevation rainfall-driven drainages (Group B). Annual maximum temperatures for Group A ranged from 15 to 20 degree(s)C, expressed as the 7-day average of the daily maximum (7dADM), whereas annual maximum 7dADM temperatures for Group B ranged from 21 to 25 degrees C. Because summertime stream temperature is at least somewhat dependent on the upstream water source, it was important when estimating without-dam temperatures to use correlations to sites with similar upstream characteristics. For that reason, it also is important to maintain long-term, year-round temperature measurement stations at representative sites in each of the Willamette River basin's physiographic regions. Streamflow and temperature estimates downstream of the major dam sites and throughout the Willamette River were generated using existing CE-QUAL-W2 flow and temperature models. These models, originally developed for the Willamette River water-temperature Total Maximum Daily Load process, required only a few modifications to allow them to run under the greatly reduced without-dam flow conditions. Model scenarios both with and without upstream dams were run. Results showed that Willamette River streamflow without upstream dams was reduced to levels much closer to historical pre-dam conditions, with annual minimum streamflows approximately one-half or less of dam-augmented levels. Thermal effects of the dams varied according to the time of year, from cooling in mid-summer to warm

  18. A Laboratory to Demonstrate the Effect of Thermal History on Semicrystalline Polymers Using Rapid Scanning Rate Differential Scanning Calorimetry

    Science.gov (United States)

    Badrinarayanan, Prashanth; Kessler, Michael R.

    2010-01-01

    A detailed understanding of the effect of thermal history on the thermal properties of semicrystalline polymers is essential for materials scientists and engineers. In this article, we describe a materials science laboratory to demonstrate the effect of parameters such as heating rate and isothermal annealing conditions on the thermal behavior of…

  19. Modelling of segmented high-performance thermoelectric generators with effects of thermal radiation, electrical and thermal contact resistances.

    Science.gov (United States)

    Ouyang, Zhongliang; Li, Dawen

    2016-04-07

    In this study, segmented thermoelectric generators (TEGs) have been simulated with various state-of-the-art TE materials spanning a wide temperature range, from 300 K up to 1000 K. The results reveal that by combining the current best p-type TE materials, BiSbTe, MgAgSb, K-doped PbTeS and SnSe with the strongest n-type TE materials, Cu-Doped BiTeSe, AgPbSbTe and SiGe to build segmented legs, TE modules could achieve efficiencies of up to 17.0% and 20.9% at ΔT = 500 K and ΔT = 700 K, respectively, and a high output power densities of over 2.1 Watt cm(-2) at the temperature difference of 700 K. Moreover, we demonstrate that successful segmentation requires a smooth change of compatibility factor s from one end of the TEG leg to the other, even if s values of two ends differ by more than a factor of 2. The influence of the thermal radiation, electrical and thermal contact effects have also been studied. Although considered potentially detrimental to the TEG performance, these effects, if well-regulated, do not prevent segmentation of the current best TE materials from being a prospective way to construct high performance TEGs with greatly enhanced efficiency and output power density.

  20. Influence of gas pressure on the effective thermal conductivity of ceramic breeder pebble beds

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Weijing [School of Civil Engineering, The University of Sydney, Sydney (Australia); Pupeschi, Simone [Institute for Applied Materials, Karlsruhe Institute of Technology (KIT) (Germany); Hanaor, Dorian [School of Civil Engineering, The University of Sydney, Sydney (Australia); Institute for Materials Science and Technologies, Technical University of Berlin (Germany); Gan, Yixiang, E-mail: yixiang.gan@sydney.edu.au [School of Civil Engineering, The University of Sydney, Sydney (Australia)

    2017-05-15

    Highlights: • This study explicitly demonstrates the influence of the gas pressure on the effective thermal conductivity of pebble beds. • The gas pressure influence is shown to correlated to the pebble size. • The effective thermal conductivity is linked to thermal-mechanical properties of pebbles and packing structure. - Abstract: Lithium ceramics have been considered as tritium breeder materials in many proposed designs of fusion breeding blankets. Heat generated in breeder pebble beds due to nuclear breeding reaction must be removed by means of actively cooled plates while generated tritiums is recovered by purge gas slowly flowing through beds. Therefore, the effective thermal conductivity of pebble beds that is one of the governing parameters determining heat transport phenomenon needs to be addressed with respect to mechanical status of beds and purge gas pressure. In this study, a numerical framework combining finite element simulation and a semi-empirical correlation of gas gap conduction is proposed to predict the effective thermal conductivity. The purge gas pressure is found to vary the effective thermal conductivity, in particular with the presence of various sized gaps in pebble beds. Random packing of pebble beds is taken into account by an approximated correlation considering the packing factor and coordination number of pebble beds. The model prediction is compared with experimental observation from different sources showing a quantitative agreement with the measurement.

  1. Analysis on the effect of hypersonic vehicle's optical window on infrared thermal imaging system

    Science.gov (United States)

    Dong, Liquan; Han, Ying; Kong, Lingqin; Liu, Ming; Zhao, Yuejin; Zhang, Li; Li, Yanhong; Tian, Yi; Sa, Renna

    2015-08-01

    According to the aero-thermal effects and aero-thermal radiation effects of the optical window, the thermo-optic effect, the elasto-optical effect and the thermal deformation of the optical window are analyzed using finite element analysis method. Also, the peak value and its location of the point spread function, which is caused by the thermo-optic effect and the dome thermal deformation, are calculated with the variance of time. Furthermore, the temperature gradient influence to the transmission of optical window, the variation trend of transmission as well as optical window radiation with time are studied based on temperature distribution analysis. The simulations results show that: When the incident light is perpendicular to the optical window, image shift is mainly caused by its thermal deformation, and the value of image shift is very small. Image shift is determined only by the angle of the incident light. With a certain incident angle, image shift is not affected by the gradient refractive index change. The optical window transmission is mainly affected by temperature gradient and thus not neglectable to image quality. Therefore, the selection of window cooling methods, needs not only consider the window temperature but try to eliminate the temperature gradient. When calculating the thermal radiation, the optical window should be regarded as volume radiation source instead of surface radiator. The results provide the basis for the optical window design, material selection and the later image processing.

  2. Thermal effects and beam parameter variations in electron guns

    CERN Document Server

    Khodak, I V; Stepin, D L

    2001-01-01

    The paper described results of research on influence of electrode temperatures and manufacturing tolerance of an electron gun on parameters of an output beam. The Pierce's gun that provides an electron beam with a current of 1.2 A and energy of 25 keV for the S-band technological linac is considered as an example. Numerically calculated parameters of the beam and the temperature distribution in electrodes are presented.It is shown that the acceptable error in a position of electrodes is +- 0.1 mm. This value does not fall outside the limit of thermal deformations and technical abilities for manufacturing guns in a laboratory. The scaling to the area of injectors for compact X-band linacs leads to the tolerance of +-0.01 mm that requires introducing fixing and adjustment elements reducing a thermal insulation of the cathode. However, the calculation and experiment showed that such reducing is negligible even for the modern low temperature thermionic cathodes due to a dominant role of the radiation in the heat ...

  3. Effect of pore size and shape on the thermal conductivity of metal-organic frameworks.

    Science.gov (United States)

    Babaei, Hasan; McGaughey, Alan J H; Wilmer, Christopher E

    2017-01-01

    We investigate the effect of pore size and shape on the thermal conductivity of a series of idealized metal-organic frameworks (MOFs) containing adsorbed gas using molecular simulations. With no gas present, the thermal conductivity decreases with increasing pore size. In the presence of adsorbed gas, MOFs with smaller pores experience reduced thermal conductivity due to phonon scattering introduced by gas-crystal interactions. In contrast, for larger pores (>1.7 nm), the adsorbed gas does not significantly affect thermal conductivity. This difference is due to the decreased probability of gas-crystal collisions in larger pore structures. In contrast to MOFs with simple cubic pores, the thermal conductivity in structures with triangular and hexagonal pore channels exhibits significant anisotropy. For different pore geometries at the same atomic density, hexagonal channel MOFs have both the highest and lowest thermal conductivities, along and across the channel direction, respectively. In the triangular and hexagonal channeled structures, the presence of gas molecules has different effects on thermal conductivity along different crystallographic directions.

  4. The Effect of Thermal Annealing Processes on Structural and Photoluminescence of Zinc Oxide Thin Film

    Directory of Open Access Journals (Sweden)

    Huai-Shan Chin

    2013-01-01

    Full Text Available This study used radio frequency sputtering at room temperature to prepare a zinc oxide (ZnO thin film. After deposition, the thin film was placed in a high-temperature furnace to undergo thermal annealing at different temperatures (300, 400, 500, and 600°C and for different dwelling times (15, 30, 45, and 60 min. The objective was to explore the effects that the described process had on the thin film’s internal structure and luminescence properties. A scanning electron microscope topographic image showed that the size of the ZnO crystals grew with increases in either the thermal annealing temperature or the dwelling time. However, significant differences in the levels of influence caused by increasing the thermal annealing temperature or dwelling time existed; the thermal annealing temperature had a greater effect on crystal growth when compared to the dwelling time. Furthermore, the crystallization directions of ZnO (002, (101, (102, and (103 can be clearly observed through an X-ray diffraction analysis, and crystallization strength increased with an increase in the thermal annealing temperature. The photoluminescence measurement spectra showed that ultraviolet (UV emission intensity increased with increases in thermal annealing temperature and dwelling time. However, when the thermal annealing temperature reached 600°C or when the dwelling time reached 60 min, even exhibited a weak green light emission peak.

  5. Effect of the Kapitza temperature jump on thermal processes in nanofluids

    Directory of Open Access Journals (Sweden)

    Novopashin Sergey

    2016-01-01

    Full Text Available Two analytical solutions describing thermal processes in a nanofluid based on spherical nanoparticles taking into account the Kapitza temperature jump on a particle-fluid boundary were found. In the first solution the thermal conductivity of nanofluids was found with the help of Maxwell approach. The second solution describes stationary heat exchange between a spherical particle and fluid in two different conditions. A dimensionless criterion characterizing the effect of the Kapitza temperature jump on thermal processes in nanofluids has been obtained in both solutions.

  6. Isotopic effect on thermal physical properties of isotopically modified boron single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Quanli [Japan Science and Technology Corporation, Kawaguchi, Saitama (Japan); Noda, Tetsuji; Suzuki, Hiroshi; Araki, Hiroshi; Numazawa, Takenori; Hirano, Toshiyuki [National Institute for Materials Science, Tsukuba, Ibaraki (Japan); Nogi, Naoyuki; Tanaka, Satoru [University of Tokyo, Department of Quantum Engineering and Systems Science, Tokyo (Japan)

    2002-04-01

    The measurement of specific heat and thermal conductivity at low temperature for isotopically modified boron single crystals was performed between 0.5 and 100K using relaxation method and steady heat flow method, respectively. The results indicate that the specific heat has obvious divergences at T<5K. At 40K, the thermal conductivity of {sup 10}B-enriched crystal is about 570 W/m{center_dot}K, which is 40% larger than that of natural boron crystal. The influence of lattice vibration modes and the isotopic effect on specific heat and thermal conductivity for isotopically modified boron are discussed. (author)

  7. Effect of Filler Concentration on Thermal Stability of Vinyl Copolymer Elastomer (VCE) Composites

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Dali [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hubbard, Kevin Mark [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Devlin, David James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Henderson, Kevin C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pacheco, Robin Montoya [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-06

    To study the thermal stability of vinyl copolymer elastomer (VCE) in its composite form, systematic TGA characterizations were conducted in both nonisothermal and isothermal modes. The effects of filler concentration on the aging behaviors of the VCE/filler composites were investigated under nitroplasticizer (NP) environment. FTIR characterization was used to probe the structural changes in the VCE polymer before and after the thermal treatments. This study suggests that the filler concentration significantly deteriorates the thermal stability of NP at a moderate temperature (< 70 °C). The degradation of NP, in turn, accelerates the aging process of the VCE polymer in its composite form.

  8. Moisture dependent thermal properties of hydrophilic mineral wool: application of the effective media theory

    Directory of Open Access Journals (Sweden)

    Iñigo Antepara

    2015-09-01

    Full Text Available Thermal properties of mineral wool based materials appear to be of particular importance for their practical applications because the majority of them is used in the form of thermal insulation boards. Every catalogue list of any material producer of mineral wool contains thermal conductivity, sometimes also specific heat capacity, but they give only single characteristic values for dry state of material mostly. Exposure to outside climate or any other environment containing moisture can negatively affect the thermal insulation properties of mineral wool. Nevertheless, the mineral wool materials due to their climatic loading and their environmental exposure contain moisture that can negatively affect their thermal insulation properties. Because the presence of water in mineral wool material is undesirable for the majority of applications, many products are provided with hydrophobic substances. Hydrophilic additives are seldom used in mineral wool products. However, this kind of materials has a good potential for application for instance in interior thermal insulation systems, masonry desalination, green roofs, etc. For these materials, certain moisture content must be estimated and thus their thermal properties will be different than for the dry state. On this account, moisture dependent thermal properties of hydrophilic mineral wool (HMW are studied in a wide range of moisture content using a pulse technique. The experimentally determined thermal conductivity data is analysed using several homogenization formulas based on the effective media theory. In terms of homogenization, a porous material is considered as a mixture of two or three phases. In case of dry state, material consists from solid and gaseous phase. When moistened, liquid phase is also present. Mineral wool consists of the solid phase represented by basalt fibers, the liquid phase by water and the gaseous phase by air. At first, the homogenization techniques are applied for the

  9. Effect of metallic nanoparticle fillers on the thermal conductivity of diatomaceous earth

    Energy Technology Data Exchange (ETDEWEB)

    Diallo, Mouhamad S. [Department of Liberal Arts, Des Moines Area Community College, Des Moines, IA 50314 (United States); Department of Mechanical Engineering, Iowa State University, Ames, IA 50011 (United States); Srinivasan, Srilok [Department of Mechanical Engineering, Iowa State University, Ames, IA 50011 (United States); Chang, Boyce [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States); Ghosh, Suvojit [Department of Engineering Physics, McMaster University, Hamilton, ON L8S4L8 (Canada); Balasubramanian, Ganesh, E-mail: bganesh@iastate.edu [Department of Mechanical Engineering, Iowa State University, Ames, IA 50011 (United States)

    2016-10-23

    Thermal conductivity of solid nanoparticles (aluminum) in a nanoporous solid matrix (diatomaceous earth) is examined to understand the effect of conductive fillers on the thermal properties of a porous material. We find that thermal conductivity is strongly dependent on load applied to prepare the mixture compacts, while porosity is influenced by the composition of the mixture. The addition of nanoparticles contributes to limited increases in thermal conductivity of the mixture by (1) increasing contact area between the mixture constituents and (2) reduction of porosity that leads to enhanced solid–gas coupling contribution. Thermal conductivity increases exponentially with external gas pressures due to the coupling effect between the solid particles and the entrapped air. - Highlights: • Thermal conductivity k of DE/AlNP mixture is more dependent on compaction than on Al concentration. • Nanoparticles affect k of DE by increase in solid contact area rather than by its effect on porosity. • When air content in mixture rises, k increases with gas pressures due to solid–gas coupling effect.

  10. Thermal Bridge Effect of Aerated Concrete Block Wall in Cold Regions

    Science.gov (United States)

    Li, Baochang; Guo, Lirong; Li, Yubao; Zhang, Tiantian; Tan, Yufei

    2018-01-01

    As a self-insulating building material which can meet the 65 percent energy-efficiency requirements in cold region of China, aerated concrete blocks often go moldy, frost heaving, or cause plaster layer hollowing at thermal bridge parts in the extremely cold regions due to the restrictions of environmental climate and construction technique. L-shaped part and T-shaped part of aerated concrete walls are the most easily influenced parts by thermal bridge effect. In this paper, a field test is performed to investigate the scope of the thermal bridge effect. Moreover, a heat transfer calculation model for L-shaped wall and T-shaped wall is developed. According to the simulation results, the temperature fields of the thermal bridge affected regions are simulated and analyzed. The research outputs can provide theoretical basis for the application of aerated concrete wall in extremely cold regions.

  11. The effect of interphase on residual thermal stresses. 2. Unidirectional fiber composite materials

    Science.gov (United States)

    Kushnevsky, V.; Bledzki, A. K.

    1997-03-01

    In real composite materials an additional phase may exist between the fiber and the matrix. This phase, commonly known as the interphase, is a local region that results from the matrix bonds with the fiber surface or the fiber sizing. The differing thermal expansions or contractions of the fiber and matrix cause thermally induced stresses in composite materials. In the present study, a four-cylinder model is proposed for the determination of residual thermal stresses in unidirectional composite materials. The elastic modulus of the interphase is a function of the interphase radius and thickness. The governing equations in terms of displacements are solved in the form of expansion into a series [1]. The effective elastic characteristics are obtained using the finite element approach. The effect of the interphase thickness and different distributions of the interphase Young's modulus on the thermal residual stress field in unidirectional composite materials is investigated.

  12. Effect of Thermal Cycling on the Tensile Behavior of CF/AL Fiber Metal Laminates

    Directory of Open Access Journals (Sweden)

    Muhammad Farhan Noor

    2017-09-01

    Full Text Available The objective of this research work was to estimate the effect of thermal cycling on the tensile behavior of CARALL composites. Fiber metal laminates (FMLs, based on 2D woven carbon fabric and 2024-T3 Alclad aluminum alloy sheet, was manufactured by pressure molding technique followed by hand layup method. Before fabrication, aluminum sheets were anodized with phosphoric acid to produce micro porous alumina layer on surface. This micro-porous layer is beneficial to produce strong bonding between metal and fiber surfaces in FMLs. The effect of thermal cycling (-65 to +70ºC on the tensile behavior of Cf/Al based FML was studied. Tensile strength was increased after 10 thermal cycles, but it was slightly decreased to some extent after 30, and 50 thermal cycles. Tensile modulus also shown the similar behavior as that of tensile strength.

  13. 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...

  14. Thermal Load Effect on Print Quality of Ink Jet Printined Textile Materials

    Directory of Open Access Journals (Sweden)

    Dragana Grujić

    2013-11-01

    Full Text Available Printed textile materials are often exposed to certain external impacts. One of the most common impact, these materials are subjected to, is thermal load. This effect causes certain changes in textile fibers as well as changes of ink colour reproduction printed on these materials. In this paper is presented an investigation of the series of thermal loads effects on print quality parameters of digitally produced impressions on textile substrates. The research includes basic print quality attributes: colour reproduction, macro non-uniformity and quality of line reproduction. Investigation results indicate that by increasing number of thermal loads, bigger changes in colour reproduction occur. Also, the influence of the series of thermal loads on mottle and line reproduction variations is confirmed, as well as the influence of printing substrate characteristics on print quality.

  15. A Network Model for the Effective Thermal Conductivity of Rigid Fibrous Refractory Insulations

    Science.gov (United States)

    Marschall, Jochen; Cooper, D. M. (Technical Monitor)

    1995-01-01

    A procedure is described for computing the effective thermal conductivity of a rigid fibrous refractory insulation. The insulation is modeled as a 3-dimensional Cartesian network of thermal conductance. The values and volume distributions of the conductance are assigned to reflect the physical properties of the insulation, its constituent fibers, and any permeating gas. The effective thermal conductivity is computed by considering the simultaneous energy transport by solid conduction, gas conduction and radiation through a cubic volume of model insulation; thus the coupling between heat transfer modes is retained (within the simplifications inherent to the model), rather than suppressed by treating these heat transfer modes as independent. The model takes into account insulation composition, density and fiber anisotropy, as well as the geometric and material properties of the constituent fibers. A relatively good agreement, between calculated and experimentally derived thermal conductivity values, is obtained for a variety of rigid fibrous insulations.

  16. Thermal effect on the morphology and performance of organic photovoltaics.

    Science.gov (United States)

    Kawashima, Eisuke; Fujii, Mikiya; Yamashita, Koichi

    2016-09-29

    The morphology of organic photovoltaics (OPVs) is a significant factor in improving performance, and establishing a method for controlling morphology is necessary. In this study, we propose a device-size simulation model, combining reptation and the dynamic Monte Carlo (DMC) algorithm, to investigate the relationship between the manufacturing process, morphology, and OPV performance. The reptation reproduces morphologies under thermal annealing, and DMC showed morphology-dependence of performance: not only short-circuit current density but also open-circuit voltage had optimal interfacial areas due to competition between exciton dissociation and charge collection. Besides, we performed transient absorption spectroscopy of various BHJ morphologies under realistic conditions, which revealed prompt and delayed dynamics of charge generation-the majority of the charges were from excitons that were generated on interfaces and dissociated within a few picoseconds, and the others from excitons that migrated to interfaces and dissociated on the order of sub-nanoseconds.

  17. Study of thermal effects of silicate-containing hydroxyapatites

    Science.gov (United States)

    Golovanova, O. A.; Zaits, A. V.; Berdinskaya, N. V.; Mylnikova, T. S.

    2016-02-01

    The possibility of modifications of hydroxyapatite silicate ions, from the extracellular fluid prototype solution under near-physiological conditions has been studied. Formation of silicon-structured hydroxyapatite with different extent of substitution of phosphate groups in the silicate group has been established through chemical and X-ray diffraction analyses, FTIR spectroscopy and optical microscopy. The results obtained are in agreement and suggest the possibility of substitution of phosphate groups for silicate groups in the hydroxyapatite structure when introducing different sources of silica, tetraethoxysilane and sodium silicate, in the reaction mixture. Growth in the amount of silicon in Si-HA results in the increase in the thermal stability of the samples. The greatest mass loss occurs at temperatures in the range of 25-400 0C that is caused by the removal of the crystallization and adsorption water and volatile impurities. It is shown that the modified apatites are of imperfect structure and crystallize in a nanocrystalline state.

  18. Thermal effects of carbonated hydroxyapatite modified by glycine and albumin

    Science.gov (United States)

    Gerk, S. A.; Golovanova, O. A.; Kuimova, M. V.

    2017-01-01

    In this work calcium phosphate powders were obtained by precipitation method from simulated solutions of synovial fluid containing glycine and albumin. X-ray diffraction and IR spectroscopy determined that all samples are single-phase and are presented by carbonate containing hydroxyapatite (CHA). The thermograms of solid phases of CHA were obtained and analyzed; five stages of transformation in the temperature range of 25-1000°C were marked. It is shown that in this temperature range dehydration, decarboxylation and thermal degradation of amino acid and protein connected to the surface of solid phase occur. The tendency of temperature lowering of the decomposition of powders synthesized from a medium containing organic substances was determined. Results demonstrate a direct dependence between the concentration of the amino acid in a model solution and its content in the solid phase.

  19. Effects of additives on thermal stability of Li ion cells

    Science.gov (United States)

    Doughty, Daniel H.; Roth, E. Peter; Crafts, Chris C.; Nagasubramanian, G.; Henriksen, Gary; Amine, Khalil

    Li ion cells are being developed for high-power applications in hybrid electric vehicles, because these cells offer superior combination of power and energy density over current cell chemistries. Cells using this chemistry are proposed for battery systems in both internal combustion engine and fuel cell-powered hybrid electric vehicles. However, the safety of these cells needs to be understood and improved for eventual widespread commercial applications. The thermal-abuse response of Li ion cells has been improved by the incorporation of more stable anode carbons and electrolyte additives. Electrolyte solutions containing vinyl ethylene carbonate (VEC), triphenyl phosphate (TPP), tris(trifluoroethyl)phosphate (TFP) as well as some proprietary flame-retardant additives were evaluated. Test cells in the 18,650 configuration were built at Sandia National Laboratories using new stable electrode materials and electrolyte additives. A special test fixture was designed to allow determination of self-generated cell heating during a thermal ramp profile. The flammability of vented gas and expelled electrolyte was studied using a novel arrangement of a spark generator placed near the cell to ignite vent gas if a flammable gas mixture was present. Flammability of vent gas was somewhat reduced by the presence of certain additives. Accelerating rate calorimetry (ARC) was also used to characterize 18,650-size test cell heat and gas generation. Gas composition was analyzed by gas chromatography (GC) and was found to consist of CO 2, H 2, CO, methane, ethane, ethylene and small amounts of C1-C4 organic molecules.

  20. Thermal Ablative Therapies and Immune Checkpoint Modulation: Can Locoregional Approaches Effect a Systemic Response?

    Directory of Open Access Journals (Sweden)

    Amol Mehta

    2016-01-01

    Full Text Available Percutaneous image-guided ablation is an increasingly common treatment for a multitude of solid organ malignancies. While historically these techniques have been restricted to the management of small, unresectable tumors, there is an expanding appreciation for the systemic effects these locoregional interventions can cause. In this review, we summarize the mechanisms of action for the most common thermal ablation modalities and highlight the key advances in knowledge regarding the interactions between thermal ablation and the immune system.

  1. Effect of plastic deformation on the low-temperature minimum of the thermal emf of copper

    Science.gov (United States)

    Svetlov, V. N.

    2012-02-01

    The effect of plastic deformation on the thermal emf and electrical resistance of polycrystalline copper is studied at low temperatures. Primary attention is devoted to the minimum in the thermal emf near 15 K and the changes in it during plastic deformation on the order of and less than 100%. These studies offer the prospect of deeper understanding of the mechanisms of electron scattering in metals with defects.

  2. Investigation of Thermal Acoustic Effects on SRF Cavities within CM1 at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    McGee, Mike [Fermilab; Harms, Elvin [Fermilab; Klebaner, Arkadiy [Fermilab; Leibfritz, Jerry [Fermilab; Martinez, Alex [Fermilab; Pischalnikov, Yuriy [Fermilab; Schappert, Warren [Fermilab

    2016-06-01

    Two TESLA-style 8-cavity cryomodules have been operated at Fermilab Accelerator Science and Technology (FAST), formerly the Superconducting Radio Frequency (SRF) Accelerator Test Facility. Operational instabilities were revealed during Radio Frequency (RF) power studies. These observations were complemented by the characterization of thermal acoustic effects on cavity microphonics manifested by apparent noisy boiling of helium involving vapor bubble and liquid vibration. The thermal acoustic measurements also consider pressure and temperature spikes which drive the phenomenon at low and high frequencies.

  3. Thermal effects on aquatic organisms: an annotated bibliography of the 1976 literature

    Energy Technology Data Exchange (ETDEWEB)

    Talmage, S.S. (comp.)

    1978-05-01

    This bibliography, containing 784 annotated references on the effects of temperature on aquatic organisms, is part of an assessment of the literature on the effects of thermal power plants on the environment. The effects of thermal discharges at power plant sites are emphasized. Laboratory and field studies on temperature tolerance and the effects of temperature changes on reproduction, development, growth, distribution, physiology, and sensitivity to other stresses are included. Indexes are provided for author, keywords, subject category, geographic location of the study, taxon, and title (alphabetical listing of keywords-in-context of nontrivial words in the title).

  4. Thermal behavior of latent thermal energy storage unit using two phase change materials: Effects of HTF inlet temperature

    Directory of Open Access Journals (Sweden)

    Fouzi Benmoussa

    2017-09-01

    Full Text Available This work presents a numerical study of the thermal behavior of shell-and-tube latent thermal energy storage (LTES unit using two phase change materials (PCMs. The heat transfer fluid (HTF flow through the inner tube and transfer the heat to PCMs. First, a mathematical model is developed based on the enthalpy formulation and solved through the governing equations. Second, the effects of HTF inlet temperature on the unsteady temperature evolution of PCMs, the total energy stored evolution as well as the total melting time is studied. Numerical results show that for all HTF inlet temperature, melting rate of PCM1 is the fastest and that of PCM2 is the slowest; increasing the HTF inlet temperature considerably increases the temperature evolution of PCMs. The maximum energy stored is observed in PCM2 with high melting temperature and high specific heat; heat storage capacity is large for high HTF inlet temperature. When the HTF inlet temperature increases from 338 K to 353 K, decreasing degree of melting time of PCM2 is the biggest from 1870 s to 490 s, which reduces about 73.8%; decreasing degree of melting time of PCM1 is the smallest from 530 s to 270 s, which reduces about 49.1%.

  5. Laser-enhanced thermal effect of moderate intensity focused ultrasound on bio-tissues

    Science.gov (United States)

    Zhao, JinYu; Zhang, ShuYi; Shui, XiuJi; Fan, Li

    2017-09-01

    For avoiding extra-damage to healthy tissues surrounding the focal point during high intensity focused ultrasound (HIFU) treatment in medical therapy, to reduce the ultrasonic intensity outside the focal point is expected. Thus, the heating processes induced by moderate intensity focused ultrasound (MIFU) and enhanced by combined irradiation of laser pulses for bio-tissues are studied in details. For fresh bio-tissues, the enhanced thermal effects by pulsed laser combined with MIFU irradiation are observed experimentally. To explore the mechanisms of these effects, several tissue-mimicking materials composed of agar mixed with graphite powders are prepared and studied for comparison, but the laser-enhanced thermal effects in these mimicking materials are much less than that in the fresh bio-tissues. Therefore, it is suggested that the laser-enhanced thermal effects may be mainly attributed to bio-activities and related photo-bio-chemical effects of fresh tissues.

  6. The Effect of Particle Size on Thermal Conduction in Granular Mixtures

    Science.gov (United States)

    Lee, Junghwoon; Yun, Tae Sup; Choi, Sung-Uk

    2015-01-01

    Shredded rubber tire is a geomaterial that is potentially useful in environmental and engineering projects. Here, we study the effect of particle size ratio on the thermal conductivity of granular mixtures containing rubber tire particles. Glass beads were mixed at various volume fractions with rubber particles of varying size. The 3D network model analysis using synthetic packed assemblies was used to determine the dominant factors influencing the thermal conduction of the mixtures. Results present that mixtures with varying size ratios exhibit different nonlinear evolutions of thermal conductivity values with mixture fractions. In particular, mixtures with large insulating materials (e.g., rubber particles) have higher thermal conduction that those with small ones. This is because the larger insulating particles allow better interconnectivity among the conductive particles, thereby avoiding the interruption of the thermal conduction of the conductive particles. Similar tests conducted with natural sand corroborate the significant effect of the relative size of the insulating particles. The 3D network model identifies the heterogeneity of local and effective thermal conductivity and the influence of connectivity among conductive particles. A supplementary examination of electrical conductivity highlights the significance of local and long-range connectivity on conduction paths in granular mixtures. PMID:28793419

  7. Longitudinal Heat Conduction Effects on a Conjugate Thermal Creep Flow in a Microchannel

    Science.gov (United States)

    Monsivais, Ian; Lizardi, José J.; Méndez, Federico

    2017-11-01

    In this work, we use asymptotic and numerical techniques to analyze the conjugate heat transfer between a rarified gas flow and the lower wall of a thin horizontal microchannel exposed to a uniform heat flux, when the laminar motion of the gas is only caused by the thermal creep or transpiration effect on the lower wall of the microchannel. Usually, it is enough to impose a linear temperature profile as a boundary condition to produce the thermal creep effect. However, we prefer to avoid this arbitrary simplification taking into account that for real cases, the temperature profile at the lower wall can be unknown. We can assume then that the lower face of this heat sink with finite thermal conductivity and thickness is exposed to a uniform heat flux, while the upper wall of the microchannel is subject to a well-known prescribed thermal boundary condition. The resulting governing equations are written in dimensionless form, assuming that the Reynolds number associated with the characteristic velocity of the thermal creep and the aspect ratio of the microchannel, are both very small. Thermal creep effect depends strongly on a dimensionless conjugate parameter that represents the competition between the heat driven by the gas and the heat that longitudinally conducts the lower wall.

  8. Effects of hypoxia and ocean acidification on the upper thermal niche boundaries of coral reef fishes.

    Science.gov (United States)

    Ern, Rasmus; Johansen, Jacob L; Rummer, Jodie L; Esbaugh, Andrew J

    2017-07-01

    Rising ocean temperatures are predicted to cause a poleward shift in the distribution of marine fishes occupying the extent of latitudes tolerable within their thermal range boundaries. A prevailing theory suggests that the upper thermal limits of fishes are constrained by hypoxia and ocean acidification. However, some eurythermal fish species do not conform to this theory, and maintain their upper thermal limits in hypoxia. Here we determine if the same is true for stenothermal species. In three coral reef fish species we tested the effect of hypoxia on upper thermal limits, measured as critical thermal maximum (CT max ). In one of these species we also quantified the effect of hypoxia on oxygen supply capacity, measured as aerobic scope (AS). In this species we also tested the effect of elevated CO 2 (simulated ocean acidification) on the hypoxia sensitivity of CT max We found that CT max was unaffected by progressive hypoxia down to approximately 35 mmHg, despite a substantial hypoxia-induced reduction in AS. Below approximately 35 mmHg, CT max declined sharply with water oxygen tension ( P w O 2 ). Furthermore, the hypoxia sensitivity of CT max was unaffected by elevated CO 2 Our findings show that moderate hypoxia and ocean acidification do not constrain the upper thermal limits of these tropical, stenothermal fishes. © 2017 The Author(s).

  9. The Effect of Particle Size on Thermal Conduction in Granular Mixtures

    Directory of Open Access Journals (Sweden)

    Junghwoon Lee

    2015-07-01

    Full Text Available Shredded rubber tire is a geomaterial that is potentially useful in environmental and engineering projects. Here, we study the effect of particle size ratio on the thermal conductivity of granular mixtures containing rubber tire particles. Glass beads were mixed at various volume fractions with rubber particles of varying size. The 3D network model analysis using synthetic packed assemblies was used to determine the dominant factors influencing the thermal conduction of the mixtures. Results present that mixtures with varying size ratios exhibit different nonlinear evolutions of thermal conductivity values with mixture fractions. In particular, mixtures with large insulating materials (e.g., rubber particles have higher thermal conduction that those with small ones. This is because the larger insulating particles allow better interconnectivity among the conductive particles, thereby avoiding the interruption of the thermal conduction of the conductive particles. Similar tests conducted with natural sand corroborate the significant effect of the relative size of the insulating particles. The 3D network model identifies the heterogeneity of local and effective thermal conductivity and the influence of connectivity among conductive particles. A supplementary examination of electrical conductivity highlights the significance of local and long-range connectivity on conduction paths in granular mixtures.

  10. Effect of oral dietary supplement for chicks subjected to thermal oscillation on performance and intestinal morphometry

    Directory of Open Access Journals (Sweden)

    Jovanir Inês Müller Fernandes

    2017-09-01

    Full Text Available The aim of the study was to evaluate the efficacy of a nutritional formulation based on amino acids and vitamins supplemented in the drinking water for chicks in the first week of life subjected to thermal oscillation on performance, organ development and intestinal morphometry from 1 to 21 days. 640-male broiler chicks were distributed in a 2x2 factorial completely randomized design (with or without dietary supplementation and at comfort temperature or thermal oscillation. Chicks subjected to thermal oscillation presented worse performance (p < 0.05 than those under thermal comfort of 1 to 7, 1 to 14 and 1 to 21 days. Nutritional supplementation did not alter the performance (p < 0.05 of the birds, but resulted in a higher body weight (p < 0.05 regardless of the environmental thermal condition. At 7 days, chicks under thermal comfort had better intestinal morphometric parameters (p < 0.05, in relation to birds under thermal oscillation. In conclusion, the temperature oscillations caused negative consequences to the productive performance and the intestinal morphology of chicks for which dietary supplementation was not enough to mitigate the effects of the environmental challenge during the first week of life of the birds.

  11. Modelling and Characterization of Effective Thermal Conductivity of Single Hollow Glass Microsphere and Its Powder.

    Science.gov (United States)

    Liu, Bing; Wang, Hui; Qin, Qing-Hua

    2018-01-14

    Tiny hollow glass microsphere (HGM) can be applied for designing new light-weighted and thermal-insulated composites as high strength core, owing to its hollow structure. However, little work has been found for studying its own overall thermal conductivity independent of any matrix, which generally cannot be measured or evaluated directly. In this study, the overall thermal conductivity of HGM is investigated experimentally and numerically. The experimental investigation of thermal conductivity of HGM powder is performed by the transient plane source (TPS) technique to provide a reference to numerical results, which are obtained by a developed three-dimensional two-step hierarchical computational method. In the present method, three heterogeneous HGM stacking elements representing different distributions of HGMs in the powder are assumed. Each stacking element and its equivalent homogeneous solid counterpart are, respectively, embedded into a fictitious matrix material as fillers to form two equivalent composite systems at different levels, and then the overall thermal conductivity of each stacking element can be numerically determined through the equivalence of the two systems. The comparison of experimental and computational results indicates the present computational modeling can be used for effectively predicting the overall thermal conductivity of single HGM and its powder in a flexible way. Besides, it is necessary to note that the influence of thermal interfacial resistance cannot be removed from the experimental results in the TPS measurement.

  12. Simplified Transient Hot-Wire Method for Effective Thermal Conductivity Measurement in Geo Materials: Microstructure and Saturation Effect

    Directory of Open Access Journals (Sweden)

    B. Merckx

    2012-01-01

    Full Text Available The thermal conductivity measurement by a simplified transient hot-wire technique is applied to geomaterials in order to show the relationships which can exist between effective thermal conductivity, texture, and moisture of the materials. After a validation of the used “one hot-wire” technique in water, toluene, and glass-bead assemblages, the investigations were performed (1 in glass-bead assemblages of different diameters in dried, water, and acetone-saturated states in order to observe the role of grain sizes and saturation on the effective thermal conductivity, (2 in a compacted earth brick at different moisture states, and (3 in a lime-hemp concrete during 110 days following its manufacture. The lime-hemp concrete allows the measurements during the setting, desiccation and carbonation steps. The recorded Δ/ln( diagrams allow the calculation of one effective thermal conductivity in the continuous and homogeneous fluids and two effective thermal conductivities in the heterogeneous solids. The first one measured in the short time acquisitions (<1 s mainly depends on the contact between the wire and grains and thus microtexture and hydrated state of the material. The second one, measured for longer time acquisitions, characterizes the mean effective thermal conductivity of the material.

  13. Analysis of effective radiant temperatures in a Pacific Northwest forest using Thermal Infrared Multispectral Scanner data

    Science.gov (United States)

    Sader, S. A.

    1986-01-01

    Analysis of Thermal Infrared Multispectral Scanner data collected over H. J. Andrews experimental forest in western Oregon indicated that aspect and slope gradient had a greater effect on the thermal emission of younger reforested clearcuts than of older stands. Older forest stands (older than 25 years) with greater amounts of green biomass and closed canopies, had lower effective radiant temperatures than younger, less dense stands. Aspect and slope had little effect on the effective radiant temperature of these older stands. Canopy temperature recorded at approximately 1:30 pm local time July 29, 1983 were nearly equal to maximum daily air temperature recorded at eight reference stands. The investigation provided some insights into the utility of the thermal sensor for detecting surface temperature differences related to forest composition and green biomass amounts in mountain terrain.

  14. Thermal Effects on the Single-Mode Regime of Distributed Modal Filtering Rod Fiber

    DEFF Research Database (Denmark)

    Coscelli, Enrico; Poli, Federica; Alkeskjold, Thomas Tanggaard

    2012-01-01

    Power scaling of fiber laser systems requires the development of innovative active fibers, capable of providing high pump absorption, ultralarge effective area, high-order mode suppression, and resilience to thermal effects. Thermally induced refractive index change has been recently appointed...... as one major limitation to the achievable power, causing degradation of the modal properties and preventing to obtain stable diffraction-limited output beam. In this paper, the effects of thermally induced refractive index change on the guiding properties of a double-cladding distributed modal filtering...... rod-type photonic crystal fiber, which exploits resonant coupling with high-index elements to suppress high-order modes, are thoroughly investigated. A computationally efficient model has been developed to calculate the refractive index change due to the thermo-optical effect, and it has been...

  15. A study of phonon anisotropic scattering effect on silicon thermal conductivity at nanoscale

    Energy Technology Data Exchange (ETDEWEB)

    Bong, Victor N-S; Wong, Basil T. [Swinburne Sarawak Research Centre for Sustainable Technologies, Faculty of Engineering, Computing & Science, Swinburne University of Technology Sarawak Campus, 93350 Kuching, Sarawak (Malaysia)

    2015-08-28

    Previous studies have shown that anisotropy in phonon transport exist because of the difference in phonon dispersion relation due to different lattice direction, as observed by a difference in in-plane and cross-plane thermal conductivity. The directional preference (such as forward or backward scattering) in phonon propagation however, remains a relatively unexplored frontier. Our current work adopts a simple scattering probability in radiative transfer, which is called Henyey and Greenstein probability density function, and incorporates it into the phonon Monte Carlo simulation to investigate the effect of directional scattering in phonon transport. In this work, the effect of applying the anisotropy scattering is discussed, as well as its impact on the simulated thermal conductivity of silicon thin films. While the forward and backward scattering will increase and decrease thermal conductivity respectively, the extent of the effect is non-linear such that forward scattering has a more obvious effect than backward scattering.

  16. Evaluation of thermal antinociceptive effects after intramuscular administration of buprenorphine hydrochloride to American kestrels (Falco sparverius).

    Science.gov (United States)

    Ceulemans, Susanne M; Guzman, David Sanchez-Migallon; Olsen, Glenn H; Beaufrère, Hugues; Paul-Murphy, Joanne R

    2014-08-01

    To evaluate the thermal antinociceptive effects and duration of action of buprenorphine hydrochloride after IM administration to American kestrels (Falco sparverius). 12 healthy 3-year-old American kestrels. Buprenorphine hydrochloride (0.1, 0.3, and 0.6 mg/kg) and a control treatment (saline [0.9% NaCl] solution) were administered IM in a randomized crossover experimental design. Foot withdrawal response to a thermal stimulus was determined 1 hour before (baseline) and 1.5, 3, and 6 hours after treatment administration. Agitation-sedation scores were determined 3 to 5 minutes before each thermal stimulus. Adverse effects were monitored for 6 hours after treatment administration. Buprenorphine hydrochloride at 0.1, 0.3, and 0.6 mg/kg, IM, increased thermal threshold for 6 hours, compared with the response for the control treatment. There were no significant differences among buprenorphine treatments. A mild sedative effect was detected at a dose of 0.6 mg of buprenorphine/kg. At the doses tested, buprenorphine hydrochloride resulted in thermal antinociception in American kestrels for at least 6 hours, which suggested that buprenorphine has analgesic effects in this species. Further studies with longer evaluation periods and additional forms of noxious stimuli, formulations, dosages, and routes of administration are needed to fully evaluate the analgesic effects of buprenorphine in American kestrels.

  17. Effect of thermal processing on the flavonols rutin and quercetin.

    Science.gov (United States)

    Buchner, Nadja; Krumbein, Angelika; Rohn, Sascha; Kroh, Lothar W

    2006-01-01

    The current research involves the study of the thermal treatment of quercetin and rutin in an aqueous model system (cooking). These substances were heated and their degradation was followed by high-performance liquid chromatography/diode-array detection (HPLC/DAD). The influence of pH and the involvement of oxygen in the degradation were studied. HPLC/electrospray ionization multi-stage mass spectrometry (ESI-MS(n)) was used for the structural characterization of the compounds produced. The influence of the degradation of the phenolic compounds on their antioxidant properties was elucidated by a electron spin resonance (ESR) spectrometry study of the reaction samples mixed with the stabilized radical, Fremy's salt. Strong degradation of the model substances took place under weak basic and oxidative conditions. Quercetin showed the most intense degradation. Protocatechuic acid could be identified as a cleavage reaction product by analyzing its retention time and molar mass during the degradation of quercetin. The structure of a second cleavage product could be identified on the basis of ESI-MS(n) fragmentation data. Also, several structures for reaction products of oxidized quercetin are suggested. The ESR analysis showed a decrease in the antioxidant activity of the reaction samples after heat treatment in aqueous solution. Copyright (c) 2006 John Wiley & Sons, Ltd.

  18. Energy Consumption of Insulated Material Using Thermal Effect Analysis

    Directory of Open Access Journals (Sweden)

    Fadzil M. A.

    2017-01-01

    Full Text Available Wall is one of the structures elements that resist direct heat from the atmosphere. Modification on several structures is relevance to reduce filtrate thermal movement on wall. Insulation material seems to be suitable to be implemented since its purpose meets the heat resistance requirement. Insulation material applied as to generate positive impact in energy saving through reduction in total building energy consumption. Fiberglass is one of the insulation materials that can be used to insulate a space from heat and sound. Fiberglass is flammable insulation material with R Value rated of R-2.9 to R-3.8 which meets the requirement in minimizing heat transfer. Finite element software, ABAQUS v6.13 employed for analyze non insulated wall and other insulated wall with different wall thicknesses. The several calculations related to overall heat movement, total energy consumption per unit area of wall, life cycle cost analysis and determination of optimal insulation thickness is calculated due to show the potential of the implementation in minimize heat transfer and generate potential energy saving in building operation. It is hoped that the study can contribute to better understanding on the potential building wall retrofitting works in increasing building serviceability and creating potential benefits for building owner.

  19. Evaluation of the effectiveness of a thermal hygienization reactor

    Directory of Open Access Journals (Sweden)

    Daniel Borski

    2011-01-01

    Full Text Available For reasons of limiting the spread of serious transmissible diseases, with regard to the requirement for reducing landfill of biodegradable waste (which may or contains animal by-products and thus presents a potential risk to human and animal health and with a focus on supporting its separate collection, there has been created a legal framework for processing and hygienization of materials containing animal by-products. For the above reasons new technologies are being developed and implemented. These technologies are able to ensure the processing of biological waste containing animal by-products. As a practical result of the effort to ensure the hygienization of biowaste, a hygienization unit of own design, which uses the thermal way of hygienization, is presented in this work. The general part of the work defines a legislative framework for the assignment and gives technical parameters and minimum requirements for conversion that hygienization unit should be able to perform, including the limits for digestion residues and compost.In the experimental section there are described operational tests which document the technological process of hygienization depending on the aeration of the contents of the reactor. Experiment III outlines the validation process which uses contamination by indicator organisms, including subsequent checking of their occurrence as well as processing of the results of experiments and evaluation of the process of hygienization.

  20. Effect of Residence Time of Graphitisation on Thermal Conductivity of Molded Graphite

    Directory of Open Access Journals (Sweden)

    Pedy Artsanti

    2010-06-01

    Full Text Available The effect of residence time of graphitisation on thermal conductivity of molded graphite has been examined. The examination has been conducted by varying residence time of graphitisation of molded carbon with petroleum coke as raw material and coal tar pitch. Graphitisation has been conducted by heating molded graphite at 2500 °C in argon atmosphere with residention time of 10, 30 and 90 minutes. Graphitisation degree, density, shrinking mass and porosity of molded graphite were examined and so was its thermal conductivity. The result showed that the decrease of porosity and the increase of graphitisation degree due to the increasing of residention time of graphitisation will increase the thermal conductivity of graphite. Molded graphite graphitisized with residence time for 90 minutes residention time gave thermal conductivity of 2.134 Watt/mK and graphitization degree 0.718.

  1. Effect of thermal modification on the physical properties of juvenile and mature woods of Eucalyptus grandis

    Directory of Open Access Journals (Sweden)

    Fred Willians Calonego

    Full Text Available This study aimed to evaluate the effect of thermal treatment on the physical properties of juvenile and mature woods of Eucalyptus grandis. Boards were taken from 30-year-old E. grandis trees. The boards were thermally modified at 180 °C in the Laboratory of Wood Drying and Preservation at UNESP, Botucatu, Sao Paulo state, Brazil. The results showed that thermal modification caused: (1 decrease of 6.8% in the density at 0% equilibrium moisture content of mature wood; (2 significant decreases of 14.7% and 35.6% in the maximum volumetric swellings of juvenile and mature woods, respectively; (3 significant decreases of 13.7% and 21.3% in the equilibrium moisture content of juvenile and mature woods, respectively. The influence of thermal modification in juvenile wood was lower than in mature wood and caused greater uniformity in the physical variations between these types of wood in E. grandis.

  2. Numerical modelling of effective thermal conductivity for modified geomaterial using lattice element method

    Science.gov (United States)

    Rizvi, Zarghaam Haider; Shrestha, Dinesh; Sattari, Amir S.; Wuttke, Frank

    2018-02-01

    Macroscopic parameters such as effective thermal conductivity (ETC) is an important parameter which is affected by micro and meso level behaviour of particulate materials, and has been extensively examined in the past decades. In this paper, a new lattice based numerical model is developed to predict the ETC of sand and modified high thermal backfill material for energy transportation used for underground power cables. 2D and 3D simulations are performed to analyse and detect differences resulting from model simplification. The thermal conductivity of the granular mixture is determined numerically considering the volume and the shape of the each constituting portion. The new numerical method is validated with transient needle measurements and the existing theoretical and semi empirical models for thermal conductivity prediction sand and the modified backfill material for dry condition. The numerical prediction and the measured values are in agreement to a large extent.

  3. A review of the combined effects of thermal and noise conditions on human performance

    Science.gov (United States)

    Moscoso, Richard A.; Wang, Lily M.; Musser, Amy

    2004-05-01

    Human perception and annoyance due to background noise has been the subject of much research. A great deal of work has also been done to identify conditions that produce an acceptable thermal environment for building occupants. The experience of occupants in indoor environments, however, is much more complex than can be represented by thermal comfort or the acoustic environment in isolation. Occupants normally experience a mix of thermal, auditory, visual, and olfactory stimuli that combines to form an impression of the environment. This paper is specifically interested in how building occupants trade off between acoustic and thermal comfort. Heating, ventilation, and air-conditioning systems in buildings are often adjusted by building users to arrive at a more comfortable temperature, but this change may also produce more noise. Previous studies on the interaction effects between temperature and noise on human performance are reviewed in this presentation, followed by a discussion of the authors' current work in this area.

  4. Feasibility of fiber-optic radiation sensor using Cerenkov effect for detecting thermal neutrons.

    Science.gov (United States)

    Jang, Kyoung Won; Yagi, Takahiro; Pyeon, Cheol Ho; Yoo, Wook Jae; Shin, Sang Hun; Misawa, Tsuyoshi; Lee, Bongsoo

    2013-06-17

    In this research, we propose a novel method for detecting thermal neutrons with a fiber-optic radiation sensor using the Cerenkov effect. We fabricate a fiber-optic radiation sensor that detects thermal neutrons with a Gd-foil, a rutile crystal, and a plastic optical fiber. The relationship between the fluxes of electrons inducing Cerenkov radiation in the sensor probe of the fiber-optic radiation sensor and thermal neutron fluxes is determined using the Monte Carlo N-particle transport code simulations. To evaluate the fiber-optic radiation sensor, the Cerenkov radiation generated in the fiber-optic radiation sensor by irradiation of pure thermal neutron beams is measured according to the depths of polyethylene.

  5. Peculiarities of determining the effective thermal conductivity of multilayer nanostructures under unsteady heating

    Science.gov (United States)

    Khvesyuk, V. I.; Chirkov, A. Yu

    2017-11-01

    Some features of pulse heating method are considered to study the main regularities of changes in the temperature of thin films in application to flash method. Heat exchange with the surrounding space is taken into account. The characteristic parameters of laser heating system are specified. The mathematical model of the heating process is based on the heat equation with effective heat conductivity. Such an analysis allows to estimate effective thermal diffusivity and thermal conductance including Kapitza conductance. For multi-layer nano-films Kapitza conductance can be estimated as its contribution to effective conductance is significant.

  6. Modification of electromagnetic fields and plasma resistance by thermal effects in helicon plasmas

    Science.gov (United States)

    Kabir, M.; Niknam, A. R.

    2017-05-01

    The effects of the thermal motion of charged particles on physical characteristics of collisional helicon plasmas are investigated. First, the dielectric permittivity tensor of a helicon plasma is obtained by considering the thermal and collisional effects in the kinetic theory. Then, the electromagnetic wave and plasma resistance equations are presented and solved in a helicon plasma source with a Nagoya type III antenna. It is shown that by increasing the temperature of plasma electrons, the effective collision frequency is increased, and consequently, the peaks of resistance profiles are lowered and broadened.

  7. Effecat of Porou Diameter on Effective Thermal Conductivity and Permeability of Porous Medium

    Science.gov (United States)

    Miyazawa, Toshiyoshi; Ichimiya, Koichi

    Effective thermal conductivity and permeability of a porous medium were examined as a function of porous diameter at constant porosity. If the porous diameter increases at constant porosity, the number of pore should reduce and as the result the contact area to solid material also decreases. Effect of solid material becomes large and effective thermal conductivity increases. This tendency was experimentally confirmed by using three kinds of ceramic material (porous diameter df=1.3mm, 2.0mm and 4.2 mm, porosity &epsilon = 87%). In addition, permeability was determined experimentally for various porous diameters by using Ergun's equation including viscous term and kinetic term.

  8. Effects of Absorber Emissivity on Thermal Performance of a Solar Cavity Receiver

    Directory of Open Access Journals (Sweden)

    Jiabin Fang

    2014-01-01

    Full Text Available Solar cavity receiver is a key component to realize the light-heat conversion in tower-type solar power system. It usually has an aperture for concentrated sunlight coming in, and the heat loss is unavoidable because of this aperture. Generally, in order to improve the thermal efficiency, a layer of coating having high absorptivity for sunlight would be covered on the surface of the absorber tubes inside the cavity receiver. As a result, it is necessary to investigate the effects of the emissivity of absorber tubes on the thermal performance of the receiver. In the present work, the thermal performances of the receiver with different absorber emissivity were numerically simulated. The results showed that the thermal efficiency increases and the total heat loss decreases with increasing emissivity of absorber tubes. However, the thermal efficiency increases by only 1.6% when the emissivity of tubes varies from 0.2 to 0.8. Therefore, the change of absorber emissivity has slight effect on the thermal performance of the receiver. The reason for variation tendency of performance curves was also carefully analyzed. It was found that the temperature reduction of the cavity walls causes the decrease of the radiative heat loss and the convective heat loss.

  9. Effects of osmolytes on Pelodiscus sinensis creatine kinase: a study on thermal denaturation and aggregation.

    Science.gov (United States)

    Wang, Wei; Lee, Jinhyuk; Jin, Qin-Xin; Fang, Nai-Yun; Si, Yue-Xiu; Yin, Shang-Jun; Qian, Guo-Ying; Park, Yong-Doo

    2013-09-01

    The protective effect of osmolytes on the thermal denaturation and aggregation of Pelodiscus sinensis muscle creatine kinase (PSCK) was investigated by a combination of spectroscopic methods and thermodynamic analysis. Our results demonstrated that the addition of osmolytes, such as glycine and proline, could prevent thermal denaturation and aggregation of PSCK in a concentration-dependent manner. When the concentration of glycine and proline increased in the denatured system, the relative activation was significantly enhanced; meanwhile, the aggregation of PSCK during thermal denaturation was decreased. Spectrofluorometer results showed that glycine and proline significantly decreased the tertiary structural changes of PSCK and that thermal denaturation directly induced PSCK aggregation. In addition, we also built the 3D structure of PSCK and osmolytes by homology models. The results of computational docking simulations showed that the docking energy was relatively low and that the clustering groups were spread to the surface of PSCK, indicating that osmolytes directly protect the surface of the protein. P. sinensis are poikilothermic and quite sensitive to the change of ambient temperature; however, there were few studies on the thermal denaturation of reptile CK. Our study provides important insight into the protective effects of osmolytes on thermal denaturation and aggregation of PSCK. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Using thermal analysis to evaluate the fire effects on organic matter content of Andisols

    Directory of Open Access Journals (Sweden)

    J. Neris

    2013-09-01

    Full Text Available Soil organic compounds play a relevant role in aggregate stability and thus, in the susceptibility of soils to erosion. Thermal analysis (N2 and air and chemical oxidation techniques (dichromate and permanganate oxidation were used to evaluate the effects of a forest fire on the organic matter of Andisols. Both thermal analysis and chemical methods showed a decrease in the organic matter content and an increase in the recalcitrance of the remaining organic compounds in the burned zones. Thermal analysis indicated an increase in the thermal stability of the organic compounds of fire-affected soils and a lower content of both labile and recalcitrant pools as a consequence of the fire. However, this decrease was relatively higher in the labile pool and lower in the recalcitrant one, indicative of an increase in the recalcitrance of the remaining organic compounds. Apparently, black carbon did not burn under our experimental conditions. Under N2, the results showed a lower labile and a higher recalcitrant and refractory contents in burned and some unburned soils, possibly due to the lower decomposition rate under N2 flux. Thermal analysis using O2 and the chemical techniques showed a positive relation, but noticeable differences in the total amount of the labile pool. Thermal analysis methods provide direct quantitative information useful to characterize the soil organic matter quality and to evaluate the effects of fire on soils.

  11. Hydrological response and thermal effect of karst springs linked to aquifer geometry and recharge processes

    Science.gov (United States)

    Luo, Mingming; Chen, Zhihua; Zhou, Hong; Zhang, Liang; Han, Zhaofeng

    2017-09-01

    To be better understand the hydrological and thermal behavior of karst systems in South China, seasonal variations in flow, hydrochemistry and stable isotope ratios of five karst springs were used to delineate flow paths and recharge processes, and to interpret their thermal response. Isotopic data suggest that mean recharge elevations are 200-820 m above spring outlets. Springs that originate from high elevations have lower NO3 - concentrations than those originating from lower areas that have more agricultural activity. Measured Sr2+ concentrations reflect the strontium contents of the host carbonate aquifer and help delineate the spring catchment's saturated zone. Seasonal variations of NO3 - and Sr2+ concentrations are inversely correlated, because the former correlates with event water and the latter with baseflow. The mean annual water temperatures of springs were only slightly lower than the local mean annual surface temperature at the outlet elevations. These mean spring temperatures suggest a vertical gradient of 6 °C/vertical km, which resembles the adiabatic lapse rate of the Earth's stable atmosphere. Seasonal temperature variations in the springs are in phase with surface air temperatures, except for Heilongquan (HLQ) spring. Event-scale variations of thermal response are dramatically controlled by the circulation depth of karst systems, which determines the effectiveness of heat exchange. HLQ spring undergoes the deepest circulation depth of 820 m, and its thermal responses are determined by the thermally effective regulation processes at higher elevations and the mixing processes associated with thermally ineffective responses at lower elevations.

  12. Changes in Effective Thermal Conductivity During the Carbothermic Reduction of Magnetite Using Graphite

    Science.gov (United States)

    Kiamehr, Saeed; Ahmed, Hesham; Viswanathan, Nurni; Seetharaman, Seshadri

    2017-06-01

    Knowledge of the effective thermal diffusivity changes of systems undergoing reactions where heat transfer plays an important role in the reaction kinetics is essential for process understanding and control. Carbothermic reduction process of magnetite containing composites is a typical example of such systems. The reduction process in this case is highly endothermic and hence, the overall rate of the reaction is greatly influenced by the heat transfer through composite compact. Using Laser-Flash method, the change of effective thermal diffusivity of magnetite-graphite composite pellet was monitored in the dynamic mode over a pre-defined thermal cycle (heating at the rate of 7 K/min to 1423 K (1150 °C), holding the sample for 270 minutes at this temperature and then cooling it down to the room temperature at the same rate as heating). These measurements were supplemented by Thermogravimetric Analysis under comparable experimental conditions as well as quenching tests of the samples in order to combine the impact of various factors such as sample dilatations and changes in apparent density on the progress of the reaction. The present results show that monitoring thermal diffusivity changes during the course of reduction would be a very useful tool in a total understanding of the underlying physicochemical phenomena. At the end, effort is made to estimate the apparent thermal conductivity values based on the measured thermal diffusivity and dilatations.

  13. Analysis of the thermal effect in diode end-pumped Er:YAG lasers by using Finite Element Method

    Science.gov (United States)

    Wang, Yujia; Wang, Qing; Na, QuanXin; Zhang, Yixuan; Gao, Mingwei; Zhang, Meng

    2018-01-01

    A new method for combining Finite Element Method (FEM) thermal analysis and thermo-mechanical coupling method for calculating the thermal lensing values in diode end-pumped Er:YAG lasers is proposed. A finite-element model is used to simulate the thermal effects in different Er:YAG crystals with pumping scenarios. The influences of pump powers, crystal absorption coefficients and crystal sizes on the Er:YAG thermal effects are discussed, and the relationship between the thermal effects and thermal lensing effects is analysed. A thermo-mechanical coupling model is also constituted for finite-element analysis based on the above results, and the focal length of the Er:YAG crystal with different pump powers are obtained by using this thermo-mechanical coupling model. The predicted thermal lensing values are compared with experimental results, which agree well with the simulated results.

  14. Thermal insulation of steep roofs. Heat insulating effects of different systems; Daemmung in Steildaechern. Die waermeschutztechnischen Wirkung unterschiedlicher Systeme

    Energy Technology Data Exchange (ETDEWEB)

    Hauser, Gerd [Technische Univ. Muenchen (Germany). Lehrstuhl Bauphysik; Fraunhofer-Institut fuer Bauphysik, Stuttgart, Holzkirchen, Kassel (Germany); Schade, Almuth; Sinnesbichler, Herbert [Fraunhofer-Institut fuer Bauphysik, Holzkirchen (Germany). Arbeitsgruppe Fassadenkonzepte

    2009-06-29

    For thermal insulation of steep roofs, so-called infrared reflecting thermal insulation materials are now available in France and also in Germany in addition to traditional thermal insulation systems. The insulating effect of these systems results primarily from the IR-reflecting surface of foils spaced at short intervals. For a comparison of the two thermal insulation systems, the Fraunhofer Institute of Constructional Physics of Holzkirchen carried out field tests and analyzed them. (orig.)

  15. Study of the solution thermal conductivity effect on nonlinear refraction of colloidal gold nanoparticles

    Science.gov (United States)

    Sarkhosh, L.; Mansour, N.

    2015-06-01

    In nanoparticle colloidal systems, the thermal nonlinearity is affected by the thermal parameters of the surrounding solution. Having a low temperature gradient rate solution may be a key factor in producing high thermal nonlinear properties in colloids. In this manuscript, the effect of the thermal conductivity of the surrounding liquid environment on the thermal nonlinear refraction of gold nanoparticles (AuNPs) synthesized by laser ablation of a gold target in different solutions is investigated. Gold nanoparticles colloids have been fabricated by the nanosecond pulsed laser ablation of a pure gold plate in different liquid environments with a thermal conductivity range of 0.14-0.60 W mK-1 including cyclohexanone, castor oil, dimethyl sulfoxide, ethylene glycol, glycerin and water. The AuNPs colloids exhibit a UV-Vis absorption spectrum with a surface plasmon absorption peak at about 540  ±  20 nm. The thermal nonlinear optical responses of the gold colloids are measured using the Z-scan technique under low power CW laser irradiation at 532 nm near the surface plasmon peak of the nanoparticles. Our results show that the nonlinear refractive index of the nanoparticle colloids is considerably affected by the thermal conductivity of liquid medium. The largest nonlinear refractive index of -3.1  ×  10-7 cm2 W-1 is obtained for AuNP in cyclohexanone with the lowest thermal conductivity of 0.14 W mK-1 whereas the lowest one of -0.1  ×  10-7 cm2 W-1 is obtained for AuNP in water with the highest thermal conductivity of 0.60 W mK-1. This study shows that the nonlinear refractive index value of colloids can be controlled by the thermal conductivity of the used liquid’s environment. This allows us to design low threshold optical limiters by choosing a solution with low thermal conductivity for colloidal nanoparticles.

  16. The effects of solar radiation and black body re-radiation on thermal comfort.

    Science.gov (United States)

    Hodder, Simon; Parsons, Ken

    2008-04-01

    When the sun shines on people in enclosed spaces, such as in buildings or vehicles, it directly affects thermal comfort. There is also an indirect effect as surrounding surfaces are heated exposing a person to re-radiation. This laboratory study investigated the effects of long wave re-radiation on thermal comfort, individually and when combined with direct solar radiation. Nine male participants (26.0 +/- 4.7 years) took part in three experimental sessions where they were exposed to radiation from a hot black panel heated to 100 degrees C; direct simulated solar radiation of 600 Wm(-2) and the combined simulated solar radiation and black panel radiation. Exposures were for 30 min, during which subjective responses and mean skin temperatures were recorded. The results showed that, at a surface temperature of 100 degrees C (close to maximum in practice), radiation from the flat black panel provided thermal discomfort but that this was relatively small when compared with the effects of direct solar radiation. It was concluded that re-radiation, from a dashboard in a vehicle, for example, will not have a major direct influence on thermal comfort and that existing models of thermal comfort do not require a specific modification. These results showed that, for the conditions investigated, the addition of re-radiation from internal components has an effect on thermal sensation when combined with direct solar radiation. However, it is not considered that it will be a major factor in a real world situation. This is because, in practice, dashboards are unlikely to maintain very high surface temperatures in vehicles without an unacceptably high air temperature. This study quantifies the contribution of short- and long-wave radiation to thermal comfort. The results will aid vehicle designers to have a better understanding of the complex radiation environment. These include direct radiation from the sun as well as re-radiation from the dashboard and other internal surfaces.

  17. The Third Way of Thermal-Electric Conversion beyond Seebeck and Pyroelectric Effects

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Jie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-02-14

    Thermal-electric conversion is crucial for smart energy control and harvesting, such as thermal sensing and waste heat recovering. So far, people are aware of only two ways of direct thermal-electric conversion, Seebeck and pyroelectric effects, each with distinct working conditions and limitations. Here, we report the third way of thermal-electric conversion beyond Seebeck and pyroelectric effects. In contrast to Seebeck effect that requires spatial temperature difference, the-third-way converts the time-dependent ambient temperature fluctuation into electricity, similar to the behavior of pyroelectricity. However, the-third-way is also distinct from pyroelectric effect in the sense that it does not require polar materials but applies to general conducting systems. We demonstrate that the-third-way results from the temperature-fluctuation-induced dynamical charge redistribution. It is a consequence of the fundamental nonequilibrium thermodynamics and has a deep connection to the topological phase in quantum mechanics. Our findings expand our knowledge and provide new means of thermal-electric energy harvesting.

  18. Thermal effect induced wafer deformation in high-energy e-beam lithography

    Science.gov (United States)

    Chen, P. S.; Wang, W. C.; Lin, S. J.

    2015-03-01

    The incident surface power density in Massive Electron-beam Direct Write (MEBDW) during exposure is ~105 W/cm2, much higher than ~8 W/cm2 ArF scanners and 2.4 W/cm2 EUV. In addition, the wafer's exposure in vacuum environment makes energy dissipation even harder. This thermal effect can cause mechanical distortion of the wafer during exposure and have has a direct influence on pattern placement error and image blur. In this paper, the thermo mechanical distortions caused by wafer heating for MEB system of different electron acceleration voltages have been simulated with finite element method (FEM). The global thermal effect affected by the friction force between the wafer and the wafer chuck as well as different thermal conductivities of the chuck material are simulated. Furthermore, the thermal effects of different lithography systems such as EUV scanners and conventional optical scanners are compared. The thermal effects of MEBDW systems are shown to be acceptable.

  19. Measurement of effective thermal conductivity of compacted granular media by the transient plane source technique

    Science.gov (United States)

    Dai, Weijing; Gan, Yixiang

    2017-06-01

    To successfully realise industrial applications handling granular media, especially those involving heating and cooling processes, the temperature fields must be properly evaluated according to the accurate thermal properties of the media. The knowledge the effective thermal conductivity is regarded as one of the fundamental aspects. However, due to the complicated relations between the effective thermal conductivity and the heterogeneity and complexity in the structures and composition of the granular media, the quantitative prediction of the conductivity is challenging. Therefore, experimental investigation of the effective thermal conductivity becomes desired and this can provide first-hand data for industrial reference and serve as the benchmark for the theoretical analysis. In this study, the transient plane source technique is employed to investigate the effective thermal conductivity of compacted granular beds by the application of the commercially available Hot Disk system. The granular beds of different particle size ranges are characterised under different mechanical loading conditions by different sensors. Experimental results are discussed and suggestion to achieve reliable experimental designs is provided.

  20. Effects of thermal energy harvesting on the human – clothing – environment microsystem

    Science.gov (United States)

    Myers, A. C.; Jur, J. S.

    2017-10-01

    The objective of this work is to perform an in depth investigation of garment-based thermal energy harvesting. The effect of human and environmental factors on the working efficiency of a thermal energy harvesting devices, or a thermoelectric generator (TEG), placed on the body is explored.. Variables that strongly effect the response of the TEG are as follows: skin temperature, human motion or speed, body location, environmental conditions, and the textile properties surrounding the TEG. In this study, the use of textiles for managing thermal comfort of wearable technology and energy harvesting are defined. By varying the stitch length and/or knit structure, one can manipulate the thermal conductivity of the garment in a specific location. Another method of improving TEG efficiency is through the use of a heat spreader, which increases the effective collection area of heat on the TEG hot side. Here we show the effect of a TEG on the thermal properties of a garment with regard to two knit stitches, jersey and 1 × 1 rib.

  1. Effective thermal penetration depth in photo-irradiated ex vivo human tissues.

    Science.gov (United States)

    Stolik, Suren; Delgado, José Alberto; Anasagasti, Lorenzo; Pérez, Arllene Mariana

    2011-10-01

    In this work, a model of bioheat distribution is discussed for ex vivo human tissue samples, and the thermal penetration depth measurements performed on several tissues are presented. Optical radiation is widely applied in the treatment and diagnosis of different pathologies. A power density of incident light at 100 mW/cm(2) is sufficiently high enough to induce a temperature increase of >5°C in irradiated human tissue. In this case, knowledge of the thermal properties of the tissue is needed to achieve a better understanding of the therapeutic effects. The application of the diffusion approximation of the radiative transfer equation for the distribution of optical radiation, the experimental setup, and the results thereof are presented and discussed. The effective thermal penetration depth in the studied tissues has been determined to be in the range of 4.3-7.0 mm. The effective thermal penetration depth has been defined, and this could be useful for developing models to describe the thermal effects with a separate analysis of the tissue itself and the blood that irrigates it.

  2. The Effects of Thermal and Cold Therapies on the Flexibility of ...

    African Journals Online (AJOL)

    The relative effects of the application of heating and cooling modalities on the muscles prior to the performance of flexibility exercises have not been extensively studied. This study was therefore designed to determine and compare the effects of thermal (heat) and cold (ice) therapies on the flexibility of the hamstring muscle ...

  3. Fractal analysis of the effect of particle aggregation distribution on thermal conductivity of nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Wei, E-mail: weiw2015@gmail.com [Hubei Subsurface Multi-scale Imaging Key Laboratory, Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074 (China); Cai, Jianchao, E-mail: caijc@cug.edu.cn [Hubei Subsurface Multi-scale Imaging Key Laboratory, Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074 (China); Hu, Xiangyun, E-mail: xyhu@cug.edu.cn [Hubei Subsurface Multi-scale Imaging Key Laboratory, Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074 (China); Han, Qi, E-mail: hanqi426@gmail.com [Hubei Subsurface Multi-scale Imaging Key Laboratory, Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074 (China); Liu, Shuang, E-mail: lius@cug.edu.cn [Hubei Subsurface Multi-scale Imaging Key Laboratory, Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074 (China); Zhou, Yingfang, E-mail: yingfang.zhou@abdn.ac.uk [School of Engineering, University of Aberdeen, FN 264, King' s College, Aberdeen, AB24 3UE (United Kingdom)

    2016-08-26

    A theoretical effective thermal conductivity model for nanofluids is derived based on fractal distribution characteristics of nanoparticle aggregation. Considering two different mechanisms of heat conduction including particle aggregation and convention, the model is expressed as a function of the fractal dimension and concentration. In the model, the change of fractal dimension is related to the variation of aggregation shape. The theoretical computations of the developed model provide a good agreement with the experimental results, which may serve as an effective approach for quantitatively estimating the effective thermal conductivity of nanofluids. - Highlights: • A thermal conductivity model is derived based on fractal aggregation distribution. • The relationship between aggregation shape and fractal dimension is analyzed. • Predictions of the proposed model show good agreement with experimental data.

  4. Study on Unit Cell Models and the Effective Thermal Conductivities of Silica Aerogel.

    Science.gov (United States)

    Liu, He; Li, Zeng-Yao; Zhao, Xin-Peng; Tao, Wen-Quan

    2015-04-01

    In this paper, two modified unit cell models, truncated octahedron and cubic array of intersecting square rods with 45-degree rotation, are developed in consideration of the tortuous path of heat conduction in solid skeleton of silica aerogel. The heat conduction is analyzed for each model and the expressions of effective thermal conductivity of the modified unit cell models are derived. Considering the random microstructure of silica aerogel, the probability model is presented. We also discuss the effect of the thermal conductivity of aerogel backbone. The effective thermal conductivities calculated by the proposed probability model are in good agreement with available experimental data when the density of the aerogel is 110 kg/m3.

  5. Autosolvent effect of bitumen in thermal cracking; Netsubunkai hanno ni okeru bitumen no jiko yobai koka

    Energy Technology Data Exchange (ETDEWEB)

    Mikuni, M.; Sato, M.; Hattori, H. [Hokkaido University, Sapporo (Japan). Center for Advanced Research of Energy Technology; Nagaishi, H.; Sasaki, M.; Yoshida, T. [Hokkaido National Industrial Research Institute, Sapporo (Japan)

    1996-10-28

    Tar sand bitumen is petroleum-based ultra-heavy oil, and has a great amount of reserve like coal. However, there are still a lot of problems for its highly effective utilization. This paper discusses whether the light components in bitumen show independent behavior during the thermal cracking of heavy components, or not. Solvent effect and reaction mechanism during the thermal cracking are also derived from the change of their chemical structures. Athabasca tar sand bitumen was separated into light and heavy fractions by vacuum distillation based on D-1660 of ASTM. Mixtures of the both fractions at various ratios were used as samples. Negative effect of the light fraction on cracking of the heavy fraction was observed with dealkylation and paraffin formation Polymerization of the dealkylated light fraction to the heavy fraction was suggested due to lack of hydrogen in the thermal cracking under nitrogen atmosphere, which resulted in the formation of polymer. 3 refs., 6 figs.

  6. Non-thermal effects of mobile phone radiation on brain

    Directory of Open Access Journals (Sweden)

    A. V. Babalyan

    2015-01-01

    Full Text Available This article gives a review of major experimental studies devoted to the effect of mobile phone electromagnetic emission on brain. The most relevant and fundamental studies were reviewed. Both positive and negative results were analyzed to give a straight answer, if mobile phone emission effects brain electrophysiology, cognitive function, subjective symptoms and blood-brain barrier permeability.

  7. Effect of pulse repetition rate on the perception of thermal sensation with pulsed shortwave diathermy.

    Science.gov (United States)

    Murray, C C; Kitchen, S

    2000-01-01

    Pulsed shortwave diathermy (PSWD) is a form of therapy commonly used to enhance tissue repair and reduce pain. It is normally considered to be an athermal form of treatment; however, there is some evidence to suggest that thermal effects can arise with adequate dosage. The purpose of this study was to determine the pulse repetition rate (PRR) required to generate a 'possible' and 'definite' thermal sensation when PSWD was applied to the thigh. Thirty healthy subjects were randomly assigned to placebo or treatment groups. The treatment group was exposed to PSWD at a constant setting of pulse duration (400 microseconds) and pulse power (190 W) while the PRR was increased from 26 Hz to 400 Hz in 10 increments. Each dose was applied for a period of two minutes. At the end of each application, subjects were asked if they felt a (1) 'possible' or (2) 'definite' thermal sensation. Skin temperature was measured immediately after each application. Placebo subjects were exposed to PSWD at its lowest settings throughout the experiment (pulse power = 5 W; pulse duration = 65 microseconds and PRR = 26 Hz). The results showed a significant correlation (p < 0.048) between PRR at 'definite' thermal sensation and skin temperature post-treatment and PRR at 'possible' thermal sensation (p < 0.001). Mean skin temperature increased significantly as PRR was increased, from 28.69 (+/- 0.75) degrees C pre-treatment to 31.14 (+/- 1.04) degrees C post-treatment, a mean difference of 2.34 degrees C. These results suggest that PSWD at adequate dosages can generate thermal effects, and that there is a relationship between these thermal effects and the PRR used. These results may have significant implications for the safe use of PSWD in the clinical arena.

  8. Geometrical effects on the concentrated behavior of heat flux in metamaterials thermal harvesting devices

    Science.gov (United States)

    Xu, Guoqiang; Zhang, Haochun; Xie, Ming; Jin, Yan

    2017-10-01

    Thermal harvesting devices based on transformation optics, which can manipulate the heat flux concentration significantly through rational arrangements of the conductivities, have attracted considerable interest owing to several great potential applications of the technique for high-efficiency thermal conversion and collection. However, quantitative studies on the geometrical effects, particularly wedge angles, on the harvesting behaviors are rare. In this paper, we adopt wedge structure-based thermal harvesting schemes, and focus on the effects of the geometrical parameters including the radii ratios and wedge angles on the harvesting performance. The temperature deformations at the boundaries of the compressional region and temperature gradients for the different schemes with varying design parameters are investigated. Moreover, a concept for temperature stabilization was derived to evaluate the fluctuation in the energy distributions. In addition, the effects of interface thermal resistances have been investigated. Considering the changes in the radii ratios and wedge angles, we proposed a modification of the harvesting efficiency to quantitatively assess the concentration performance, which was verified through random tests and previously fabricated devices. In general, this study indicates that a smaller radii ratio contributes to a better harvesting behavior, but causes larger perturbations in the thermal profiles owing to a larger heat loss. We also find that a smaller wedge angle is beneficial to ensuring a higher concentration efficiency with less energy perturbations. These findings can be used to guide the improvement of a thermal concentrator with a high efficiency in reference to its potential applications as novel heat storage, thermal sensors, solar cells, and thermoelectric devices.

  9. Effect of graphene nanoplatelets on coefficient of thermal expansion of polyetherimide composite

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Huang, E-mail: huang.wu.84@gmail.com [Composite Materials and Structures Center, Michigan State University, East Lansing, MI 48864 (United States); Department of Chemical Engineering and Material Science, Michigan State University, East Lansing, MI 48864 (United States); Drzal, Lawrence T. [Composite Materials and Structures Center, Michigan State University, East Lansing, MI 48864 (United States); Department of Chemical Engineering and Material Science, Michigan State University, East Lansing, MI 48864 (United States)

    2014-07-01

    Thermal expansion is one of the major concerns for polymer composites. In this research, graphene nanoplatelets (GNPs) were added to polyetherimide (PEId) thermoplastic polymer in order to reduce the coefficient of thermal expansion (CTE) of the injection molded composite. First, the coefficient of linear thermal expansion (LTE) was measured in three directions in the anisotropic coupon: 0°, 90° and the out of plane Z direction. It is found that the GNP particles are very effective in terms of reducing the LTE in 0° direction due to high degree of alignment. After annealing above glass transition temperature, significant increase of 0° LTE and decrease of Z° LTE were observed. The bulk CTE was calculated by adding up the LTEs in all three directions and is found to be independent of annealing. Second, several models were applied to predict both CTE and LTE. It is found that Schapery's lower limit model fits the experimental CTE very well. Chow's model was applied for LTEs in three directions. The behavior of GNP-5/PEId composites is explained by the combination of Chow's model and morphology obtained by scanning electron microscope (SEM). - Highlights: • Coefficient of thermal expansion (CTE) of polymer composite is characterized. • Reduction of linear thermal expansion depends on filler orientation. • Filler orientation is characterized based on the location of the specimen. • Filler orientation is changed by annealing, causing subsequent change in CTE. • CTE and linear thermal expansion coefficient are modeled.

  10. Revisiting the effects of organic solvents on the thermal reduction of graphite oxide

    Energy Technology Data Exchange (ETDEWEB)

    Barroso-Bujans, Fabienne, E-mail: fbarroso@ehu.es [Centro de Fisica de Materiales-Material Physics Center (CSIC-UPV/EHU), Paseo Manuel Lardizabal 5, 20018 San Sebastian (Spain); Fierro, Jose Luis G. [Instituto de Catalisis y Petroleoquimica, CSIC. Marie Curie, 2, Cantoblanco, 28049 Madrid (Spain); Alegria, Angel [Centro de Fisica de Materiales-Material Physics Center (CSIC-UPV/EHU), Paseo Manuel Lardizabal 5, 20018 San Sebastian (Spain); Departamento de Fisica de Materiales, Universidad del Pais Vasco (UPV/EHU) Apartado 1072, 20080 San Sebastian (Spain); Colmenero, Juan [Centro de Fisica de Materiales-Material Physics Center (CSIC-UPV/EHU), Paseo Manuel Lardizabal 5, 20018 San Sebastian (Spain); Departamento de Fisica de Materiales, Universidad del Pais Vasco (UPV/EHU) Apartado 1072, 20080 San Sebastian (Spain); Donostia International Physics Center, Paseo Manuel Lardizabal 4, 20018 San Sebastian (Spain)

    2011-11-10

    Highlights: Black-Right-Pointing-Pointer Retention of organic solvent on graphite oxide interlayer space. Black-Right-Pointing-Pointer Decreasing exfoliation temperature. Black-Right-Pointing-Pointer Close link between structure and thermal behavior of solvent treated graphite oxide. Black-Right-Pointing-Pointer Restacking inhibition of thermally reduced graphite oxide sheets. Black-Right-Pointing-Pointer Changes in kinetic mechanisms of thermal reduction. - Abstract: Treatment of graphite oxide (GO) with organic solvents via sorption from either liquid or gas phase, and subsequent desorption, induces profound changes in the layered GO structure: loss of stacking order, retention of trace amounts of solvents and decreasing decomposition temperature. This study presents new evidences of the effect of organic solvents on the thermal reduction of GO by means of thermogravimetric analysis, X-ray diffraction and X-ray photoelectron spectroscopy. The results reveal a relative higher decrease of the oxygen amounts in solvent-treated GO as compared to untreated GO and the restacking inhibition of the thermally reduced GO sheets upon slow heating. The kinetic experiments evidence changes occurring in the reduction mechanisms of the solvent-treated GO, which support the close link between GO structure and thermal properties.

  11. Storage effects on anthocyanins, phenolics and antioxidant activity of thermally processed conventional and organic blueberries.

    Science.gov (United States)

    Syamaladevi, Roopesh M; Andrews, Preston K; Davies, Neal M; Walters, Thomas; Sablani, Shyam S

    2012-03-15

    Consumer demand for products rich in phytochemicals is increasing as a result of greater awareness of their potential health benefits. However, processed products are stored for long-term and the phytochemicals are susceptible to degradation during storage. The objective of this study was to assess the storage effects on phytochemicals in thermally processed blueberries. Thermally processed canned berries and juice/puree were analysed for phytochemicals during their long-term storage. The phytochemical retention of thermally processed blueberries during storage was not influenced by production system (conventional versus organic). During 13 months of storage, total anthocyanins, total phenolics and total antioxidant activity in canned blueberry solids decreased by up to 86, 69 and 52% respectively. In canned blueberry syrup, total anthocyanins and total antioxidant activity decreased by up to 68 and 15% respectively, while total phenolic content increased by up to 117%. Similar trends in phytochemical content were observed in juice/puree stored for 4 months. The extent of changes in phytochemicals of thermally processed blueberries during storage was significantly influenced by blanching. Long-term storage of thermally processed blueberries had varying degrees of influence on degradation of total anthocyanins, total phenolics and total antioxidant activity. Blanching before thermal processing helped to preserve the phytochemicals during storage of blueberries. Copyright © 2011 Society of Chemical Industry.

  12. Effects of Melatonin on Adrenal Cortical Functions of Indian Goats under Thermal Stress

    Directory of Open Access Journals (Sweden)

    Veerasamy Sejian

    2010-01-01

    Full Text Available The study was conducted with the primary objective to establish the influence of melatonin on adrenocortical functions to ameliorate thermal stress in goats. Endocrine secretions and several other blood biochemical parameters reflecting the animals adrenocortical stress response were determined over a one-week period after goats had been exposed to 40C∘ and 60%RH for 10 days. The study was conducted for a period of 17 days in psychrometric chamber. The animals served as self-controls prior to start of the experiment. Blood samples were drawn on day 10 to establish effect of thermal stress. Chemical adrenalectomy was achieved using metyrapone followed by exogenous melatonin treatment. 40C∘ of thermal stress which is quite normal in tropical zone significantly (P≤.05 influenced all parameters except plasma insulin. Metyrapone treatment significantly (P≤.05 affected plasma levels of glucose, total protein, total cholesterol, cortisol, and aldosterone. Metyrapone aggravated thermal stress by decreasing cortisol level in goats. Melatonin treatment at 11:00 AM significantly (P≤.05 influenced plasma levels of glucose, total protein, total cholesterol, cortisol, aldosterone and insulin. Metyrapone treatment aggravated thermal stress although administration of melatonin could ameliorate the condition. This establishes the role of melatonin in relieving thermal stress in goats.

  13. Enhanced Thermal Conductivity of Copper Nanofluids: The Effect of Filler Geometry.

    Science.gov (United States)

    Bhanushali, Sushrut; Jason, Naveen Noah; Ghosh, Prakash; Ganesh, Anuradda; Simon, George P; Cheng, Wenlong

    2017-06-07

    Nanofluids are colloidal dispersions that exhibit enhanced thermal conductivity at low filler loadings and thus have been proposed for heat transfer applications. Here, we systematically investigate how particle shape determines the thermal conductivity of low-cost copper nanofluids using a range of distinct filler particle shapes: nanospheres, nanocubes, short nanowires, and long nanowires. To exclude the potential effects of surface capping ligands, all the filler particles are kept with uniform surface chemistry. We find that copper nanowires enhanced the thermal conductivity up to 40% at 0.25 vol % loadings; while the thermal conductivity was only 9.3% and 4.2% for the nanosphere- and nanocube-based nanofluids, respectively, at the same filler loading. This is consistent with a percolation mechanism in which a higher aspect ratio is beneficial for thermal conductivity enhancement. To overcome the surface oxidation of the copper nanomaterials and maintain the dispersion stability, we employed polyvinylpyrrolidone (PVP) as a dispersant and ascorbic acid as an antioxidant in the nanofluid formulations. The thermal performance of the optimized fluid formulations could be sustained for multiple heating-cooling cycles while retaining stability over 1000 h.

  14. Effect of cooking time on the physical, chemical and thermal properties of acha seeds

    Directory of Open Access Journals (Sweden)

    Akeem O. Raji

    2017-10-01

    Full Text Available Acha is a less utilized cereal grain in Africa. Scaling up of the processing technology of acha seeds is desirable if accurate information on effect of processing on its properties is available. This study investigated the effect of cooking duration on the chemical and physical properties of acha seeds. Cooking times (2.5, 5, 7.5 and 10 minutes at 100oC were used. The volume, length, breadth, thickness, porosity, density, sphericity, aspect ratio, specific heat capacity, thermal conductivity, thermal diffusivity, moisture, protein, fat, ash, crude fibre and carbohydrate were determined using standard methods. Data were analysed using ANOVA at p = 0.05. The results obtained revealed that varietal difference had a significant effect on volume, length, breadth, thickness, true density, bulk density, porosity, sphericity and aspect ratio. The moisture content, ash, protein, crude fibre, fat, carbohydrate, specific heat capacity, thermal conductivity and thermal diffusivity varied from 8.80 - 56.17 %, 0.32 - 1.87%, 1.92 - 11.50%, 0.29 - 1.58%, 0.32 - 2.81%, 40.94 - 76.26%, 1.66 -2.97 kJkg-1K-1, 0.26 -0.43 Wm-1K-1 and 0.85 x 10-7 - 1.17 x 10-7 ms-2 respectively, as significantly influenced by cooking time. Cooking for 7.5 minutes was appropriate using the moisture uptakes and thermal properties as criteria. 

  15. Effects of Particle Surface Charge, Species, Concentration, and Dispersion Method on the Thermal Conductivity of Nanofluids

    Directory of Open Access Journals (Sweden)

    Raghu Gowda

    2010-01-01

    Full Text Available The purpose of this experimental study is to evaluate the effects of particle species, surface charge, concentration, preparation technique, and base fluid on thermal transport capability of nanoparticle suspensions (nanofluids. The surface charge was varied by changing the pH value of the fluids. The alumina (Al2O3 and copper oxide (CuO nanoparticles were dispersed in deionized (DI water and ethylene glycol (EG, respectively. The nanofluids were prepared using both bath-type and probe sonicator under different power inputs. The experimental results were compared with the available experimental data as well as the predicted values obtained from Maxwell effective medium theory. It was found that ethylene glycol is more suitable for nanofluids applications than DI water in terms of thermal conductivity improvement and stability of nanofluids. Surface charge can effectively improve the dispersion of nanoparticles by reducing the (aggregated particle size in base fluids. A nanofluid with high surface charge (low pH has a higher thermal conductivity for a similar particle concentration. The sonication also has a significant impact on thermal conductivity enhancement. All these results suggest that the key to the improvement of thermal conductivity of nanofluids is a uniform and stable dispersion of nanoscale particles in a fluid.

  16. Effects of simultaneous climate change and geomorphic evolution on thermal characteristics of a shallow Alaskan lake

    Science.gov (United States)

    Griffiths, Jennifer R.; Schindler, Daniel E.; Balistrieri, Laurie S.; Ruggerone, Gregory T.

    2011-01-01

    We used a hydrodynamics model to assess the consequences of climate warming and contemporary geomorphic evolution for thermal conditions in a large, shallow Alaskan lake. We evaluated the effects of both known climate and landscape change, including rapid outlet erosion and migration of the principal inlet stream, over the past 50 yr as well as future scenarios of geomorphic restoration. Compared to effects of air temperature during the past 50 yr, lake thermal properties showed little sensitivity to substantial (~60%) loss of lake volume, as the lake maximum depth declined from 6 m to 4 m driven by outlet erosion. The direction and magnitude of future lake thermal responses will be driven largely by the extent of inlet stream migration when it occurs simultaneously with outlet erosion. Maintaining connectivity with inlet streams had substantial effects on buffering lake thermal responses to warming climate. Failing to account for changing rates and types of geomorphic processes under continuing climate change may misidentify the primary drivers of lake thermal responses and reduce our ability to understand the consequences for aquatic organisms.

  17. Thermal effects investigation on electrical properties of silicon solar cells treated by laser irradiation

    Directory of Open Access Journals (Sweden)

    Ali Pourakbar Saffar

    2014-12-01

    Full Text Available In this paper, we were investigated electrical properties of monocrystalline and polycrystalline silicon solar cells due to laser irradiation with 650 nm wavelength in two states, proximate irradiation and via optics setup. Thermal effect on the cell surface due to laser irradiation was investigated on electrical properties too. Electrical parameters investigation of solar cells illustrates cell excitement via laser irradiation and efficiency decreases due to cell surface temperature increase. Monocrystalline parameters change with uniform shape due to thermal effect and laser irradiation toward polycrystalline cells.

  18. Experimental investigation of the effect of graphene nanofluids on heat pipe thermal performance

    DEFF Research Database (Denmark)

    Sadeghinezhad, Emad; Mehrali, Mohammad; Rosen, Marc A.

    2016-01-01

    An experimental investigation has been carried out to examine the thermal, performance of a sintered wick heat pipe using aqueous graphene nanoplatelets (GNP) nanofluids. The study focuses on changes in the effects of GNP concentration, heat pipe inclination angle and input heating power. The max......An experimental investigation has been carried out to examine the thermal, performance of a sintered wick heat pipe using aqueous graphene nanoplatelets (GNP) nanofluids. The study focuses on changes in the effects of GNP concentration, heat pipe inclination angle and input heating power...

  19. Effects of coherent ferroelastic domain walls on the thermal conductivity and Kapitza conductance in bismuth ferrite

    Science.gov (United States)

    Hopkins, Patrick E.; Adamo, Carolina; Ye, Linghan; Huey, Bryan D.; Lee, Stephen R.; Schlom, Darrell G.; Ihlefeld, Jon F.

    2013-03-01

    Ferroelectric and ferroelastic domain structure has a profound effect on the piezoelectric, ferroelectric, and dielectric responses of ferroelectric materials. However, domain walls and strain field effects on thermal properties are unknown. We measured the thermal conductance from 100-400 K of epitaxially grown BiFeO3 thin films with different domain variants, each separated primarily by 71° domain walls. We determined the Kapitza conductance across the domain walls, which is driven by the strain field induced by the domain variants. This domain wall Kapitza conductance is lower than the Kapitza conductance associated with grain boundaries in all previously measured materials.

  20. Effects of thermal conduction and convection on temperature profile in a water calorimeter for proton beams

    Energy Technology Data Exchange (ETDEWEB)

    Gargioni, E.; Manfredotti, C. [Torino Univ. (Italy). Dipt. di Fisica; Laitano, R.F.; Guerra, A.S. [Ist. Nazionale di Metrologia delle Radiazioni Ionizzanti, ENEA, Roma (Italy)

    1997-09-01

    In water calorimetry, in addition to the temperature increase due to beam energy deposition in water, unwanted thermal effects occur during and after calorimeter irradiation. This should be accounted for by applying proper corrections to the experimental results. In order to determine such corrections heat flow calculations were performed using the `finite element` method. This method applies even to complex 3D geometries with not necessarily symmetric conditions. Some preliminary results of these calculations are presented together with a description of the analytical method for the evaluation of the correction factors that should be applied to the experimental results to account for the above thermal effects. (orig.)

  1. RF tumour ablation: computer simulation and mathematical modelling of the effects of electrical and thermal conductivity.

    Science.gov (United States)

    Lobo, S M; Liu, Z-J; Yu, N C; Humphries, S; Ahmed, M; Cosman, E R; Lenkinski, R E; Goldberg, W; Goldberg, S N

    2005-05-01

    This study determined the effects of thermal conductivity on RF ablation tissue heating using mathematical modelling and computer simulations of RF heating coupled to thermal transport. Computer simulation of the Bio-Heat equation coupled with temperature-dependent solutions for RF electric fields (ETherm) was used to generate temperature profiles 2 cm away from a 3 cm internally-cooled electrode. Multiple conditions of clinically relevant electrical conductivities (0.07-12 S m-1) and 'tumour' radius (5-30 mm) at a given background electrical conductivity (0.12 S m-1) were studied. Temperature response surfaces were plotted for six thermal conductivities, ranging from 0.3-2 W m-1 degrees C (the range of anticipated clinical and experimental systems). A temperature response surface was obtained for each thermal conductivity at 25 electrical conductivities and 17 radii (n=425 temperature data points). The simulated temperature response was fit to a mathematical model derived from prior phantom data. This mathematical model is of the form (T=a+bRc exp(dR) s(f) exp(g)(s)) for RF generator-energy dependent situations and (T=h+k exp(mR)+n?exp(p)(s)) for RF generator-current limited situations, where T is the temperature (degrees C) 2 cm from the electrode and a, b, c, d, f, g, h, k, m, n and p are fitting parameters. For each of the thermal conductivity temperature profiles generated, the mathematical model fit the response surface to an r2 of 0.97-0.99. Parameters a, b, c, d, f, k and m were highly correlated to thermal conductivity (r2=0.96-0.99). The monotonic progression of fitting parameters permitted their mathematical expression using simple functions. Additionally, the effect of thermal conductivity simplified the above equation to the extent that g, h, n and p were found to be invariant. Thus, representation of the temperature response surface could be accurately expressed as a function of electrical conductivity, radius and thermal conductivity. As a result

  2. Effect of thermal-treatment sequence on sound absorbing and mechanical properties of porous sound-absorbing/thermal-insulating composites

    Directory of Open Access Journals (Sweden)

    Huang Chen-Hung

    2016-01-01

    Full Text Available Due to recent rapid commercial and industrial development, mechanical equipment is supplemented massively in the factory and thus mechanical operation causes noise which distresses living at home. In livelihood, neighborhood, transportation equipment, jobsite construction noises impact on quality of life not only factory noise. This study aims to preparation technique and property evaluation of porous sound-absorbing/thermal-insulating composites. Hollow three-dimensional crimp PET fibers blended with low-melting PET fibers were fabricated into hollow PET/low-melting PET nonwoven after opening, blending, carding, lapping and needle-bonding process. Then, hollow PET/low-melting PET nonwovens were laminated into sound-absorbing/thermal-insulating composites by changing sequence of needle-bonding and thermal-treatment. The optimal thermal-treated sequence was found by tensile strength, tearing strength, sound-absorbing coefficient and thermal conductivity coefficient tests of porous composites.

  3. Effect of Periodic Surface Air Temperature Variations on Subsurface Thermal Structure with Vertical Fluid flow

    Science.gov (United States)

    D, R. V.; Ravi, M.; Srivastava, K.

    2016-12-01

    The influence of climate change on near subsurface temperatures is an important research topic for global change impact assessment at the regional scale. The varying temperature of the air over the surface in long term will disturb subsurface thermal structure. Groundwater flow is another important process which perturbs the thermal distribution into the subsurface. To investigate the effect of periodic air temperature on nonisothermal subsurface, one dimensional transient heat conduction-advection equation is solved numerically using finite element method. Thermal response of subsurface for periodic variations in surface air temperature (SAT) with robin type boundary condition on the surface with vertical ground water flow are calculated and the amplitude attenuation of propagation of surface temperature information in the subsurface for different scenarios of advection and convective coefficient are discussed briefly. The results show the coupled response of trigonometric variation in air temperature with surface temperatures along with ground water velocity has significant implications for the effects of climate change.

  4. The effect of thermal pre-treatment on the hydrometallurgical purification of large silicon particles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Joon-Soo; Lee, Jin-Seok; Jang, Bo-Yun; Ahn, Young-Soo [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

    2014-08-15

    The most desirable approach to the hydrometallurgical process consists in using larger silicon particles by exposing the metallic impurities contained in the silicon to its surface via a thermally activated elution prior to chemical treatment. The present study reports experimental findings concerning the effect of a thermal pre-treatment using a mixture of 5-wt% nitric acid and 2.5-wt% hydrofluoric acid for the purification of metallurgical-grade silicon particles of different sizes on the hydrometallurgical process. The extraction rates of metallic impurities from inside the silicon were in inverse proportion to the size of the silicon particle. However, the effect of the thermal pre-treatment on the extraction rate became greater with increasing particle size.

  5. Unique effects of thermal and pressure histories on glass hardness: Structural and topological origin

    Science.gov (United States)

    Smedskjaer, Morten M.; Bauchy, Mathieu; Mauro, John C.; Rzoska, Sylwester J.; Bockowski, Michal

    2015-10-01

    The properties of glass are determined not only by temperature, pressure, and composition, but also by their complete thermal and pressure histories. Here, we show that glasses of identical composition produced through thermal annealing and through quenching from elevated pressure can result in samples with identical density and mean interatomic distances, yet different bond angle distributions, medium-range structures, and, thus, macroscopic properties. We demonstrate that hardness is higher when the density increase is obtained through thermal annealing rather than through pressure-quenching. Molecular dynamics simulations reveal that this arises because pressure-quenching has a larger effect on medium-range order, while annealing has a larger effect on short-range structures (sharper bond angle distribution), which ultimately determine hardness according to bond constraint theory. Our work could open a new avenue towards industrially useful glasses that are identical in terms of composition and density, but with differences in thermodynamic, mechanical, and rheological properties due to unique structural characteristics.

  6. Temperature Effects on the Wind Direction Measurement of 2D Solid Thermal Wind Sensors

    Science.gov (United States)

    Chen, Bei; Zhu, Yan-Qing; Yi, Zhenxiang; Qin, Ming; Huang, Qing-An

    2015-01-01

    For a two-dimensional solid silicon thermal wind sensor with symmetrical structure, the wind speed and direction information can be derived from the output voltages in two orthogonal directions, i.e., the north-south and east-west. However, the output voltages in these two directions will vary linearly with the ambient temperature. Therefore, in this paper, a temperature model to study the temperature effect on the wind direction measurement has been developed. A theoretical analysis has been presented first, and then Finite Element Method (FEM) simulations have been performed. It is found that due to symmetrical structure of the thermal wind sensor, the temperature effects on the output signals in the north-south and east-west directions are highly similar. As a result, the wind direction measurement of the thermal wind sensor is approximately independent of the ambient temperature. The experimental results fit the theoretical analysis and simulation results very well. PMID:26633398

  7. Effect of fibre shape on transverse thermal conductivity of ...

    Indian Academy of Sciences (India)

    Ultimately, it is the combined resistance to the heat flow that determines the conductivity of any material. Since this combined resistance do change in a wide range with different shapes of fibres and hence are the large variations in the effective conductivity. In the case of an elliptic fibre (figure 9), there exists a possibility of ...

  8. Effect of thermal and physicochemical treatment on abattoir waste ...

    African Journals Online (AJOL)

    Evacuation of abattoir waste waters into water bodies results in excessive proliferation of decomposers, thus causing oxygen depletion and eutrophication. This study is designed to find means of effectively treating the abattoir waste water before they are reused or discharged into water bodies. The waste water was taken ...

  9. Analytical model of transient thermal effect on convectional cooled ...

    Indian Academy of Sciences (India)

    Abstract. The transient analytical solutions of temperature distribution, stress, strain and optical path difference in convectional cooled end-pumped laser rod are derived. The results are compared with other works and good agreements are found. The effects of increasing the edge cooling and face cooling are studied.

  10. Effects of thermal treatments and germination on physico-chemical ...

    African Journals Online (AJOL)

    Certain physico-chemical properties including viscoelasticity, crystallinity and maltose content of corn depends on the gelatinization of starch under different treatments. Three different treatments were performed; boiling in water, steam heating, and germination. The effects of gelatinization on viscoelastic property of corn ...

  11. Effects of thermal aging on mechanical performance of paper

    Science.gov (United States)

    B.T. Hotle; J.M. Considine; M.J. Wald; R.E. Rowlands; K.T. Turner

    2008-01-01

    A missing element of paper aging research is a description of mechanical performance with aging. Tensile strength cannot be predicted directly from DP measurements, and existing models do not represent the effects of aging on strength and stiffness. The primary aim of the present work is to characterize changes of mechanical properties, such as tensile response and...

  12. Thermal effects of water intrusion in hydrophobic nanoporous materials.

    Science.gov (United States)

    Karbowiak, Thomas; Paulin, Christian; Ballandras, Anthony; Weber, Guy; Bellat, Jean-Pierre

    2009-07-29

    Liquid water intrusion in hydrophobic nanoporous silicalite-1, a pure siliceous zeolite, in isothermal conditions under high pressure produces an endothermic effect. After intrusion, confined water in zeolite pores is in a different state from that of the liquid bulk water. Such forced intrusion also chemically modifies the material and tends to render it slightly more hydrophilic.

  13. Effects of thermal treatments and germination on physico-chemical ...

    African Journals Online (AJOL)

    GREGO

    2007-04-16

    Apr 16, 2007 ... Accepted 17 July, 2006. Certain physico-chemical properties including viscoelasticity, crystallinity and maltose content of corn ... performed; boiling in water, steam heating, and germination. The effects of gelatinization on ... changes in physical, chemical and nutritional properties of starch as well as water ...

  14. Effects of functional group mass variance on vibrational properties and thermal transport in graphene

    Science.gov (United States)

    Lindsay, L.; Kuang, Y.

    2017-03-01

    Intrinsic thermal resistivity critically depends on features of phonon dispersions dictated by harmonic interatomic forces and masses. Here we present the effects of functional group mass variance on vibrational properties and thermal conductivity (κ ) of functionalized graphene from first-principles calculations. We use graphane, a buckled graphene backbone with covalently bonded hydrogen atoms on both sides, as the base material and vary the mass of the hydrogen atoms to simulate the effect of mass variance from other functional groups. We find nonmonotonic behavior of κ with increasing mass of the functional group and an unusual crossover from acoustic-dominated to optic-dominated thermal transport behavior. We connect this crossover to changes in the phonon dispersion with varying mass which suppress acoustic phonon velocities, but also give unusually high velocity optic modes. Further, we show that out-of-plane acoustic vibrations contribute significantly more to thermal transport than in-plane acoustic modes despite breaking of a reflection-symmetry-based scattering selection rule responsible for their large contributions in graphene. This work demonstrates the potential for manipulation and engineering of thermal transport properties in two-dimensional materials toward targeted applications.

  15. Study of the thermal effect on silicon surface induced by ion beam from plasma focus device

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Z., E-mail: pscientific5@aec.org.sy [Scientific Service Department, Atomic Energy Commission of Syria, P.O. Box: 6091, Damascus (Syrian Arab Republic); Ahmad, M. [IBA Laboratory, Atomic Energy Commission of Syria, P.O. Box: 6091, Damascus (Syrian Arab Republic); Chemistry Department, Atomic Energy Commission of Syria, P.O. Box: 6091, Damascus (Syrian Arab Republic); Al-Hawat, Sh.; Akel, M. [Physics Department, Atomic Energy Commission of Syria, P.O. Box: 6091, Damascus (Syrian Arab Republic)

    2017-04-01

    Structural modifications in form of ripples and cracks are induced by nitrogen ions from plasma focus on silicon surface. The investigation of such structures reveals correlation between ripples and cracks formation in peripheral region of the melt spot. The reason of such correlation and structure formation is explained as result of thermal effect. Melting and resolidification of the center of irradiated area occur within one micro second of time. This is supported by a numerical simulation used to investigate the thermal effect induced by the plasma focus ion beams on the silicon surface. This simulation provides information about the temperature profile as well as the dynamic of the thermal propagation in depth and lateral directions. In accordance with the experimental observations, that ripples are formed in latter stage after the arrival of last ion, the simulation shows that the thermal relaxation takes place in few microseconds after the end of the ion beam arrival. Additionally, the dependency of thermal propagation and relaxation on the distance of the silicon surface from the anode is presented.

  16. Thermal effects on clay rocks for deep disposal of high-level radioactive waste

    Directory of Open Access Journals (Sweden)

    Chun-Liang Zhang

    2017-06-01

    Full Text Available Thermal effects on the Callovo-Oxfordian and Opalinus clay rocks for hosting high-level radioactive waste were comprehensively investigated with laboratory and in situ experiments under repository relevant conditions: (1 stresses covering the range from the initial lithostatic state to redistributed levels after excavation, (2 hydraulic drained and undrained boundaries, and (3 heating from ambient temperature up to 90 °C–120 °C and a subsequent cooling phase. The laboratory experiments were performed on normal-sized and large hollow cylindrical samples in various respects of thermal expansion and contraction, thermally-induced pore water pressure, temperature influences on deformation and strength, thermal impacts on swelling, fracture sealing and permeability. The laboratory results obtained from the samples are consistent with the in situ observations during heating experiments in the underground research laboratories at Bure and Mont-Terri. Even though the claystones showed significant responses to thermal loading, no negative effects on their favorable barrier properties were observed.

  17. Experimental Investigation of Size Effects on the Thermal Conductivity of Silicon-Germanium Alloy Thin Films

    Science.gov (United States)

    Cheaito, Ramez; Duda, John C.; Beechem, Thomas E.; Hattar, Khalid; Ihlefeld, Jon F.; Medlin, Douglas L.; Rodriguez, Mark A.; Campion, Michael J.; Piekos, Edward S.; Hopkins, Patrick E.

    2012-11-01

    We experimentally investigate the role of size effects and boundary scattering on the thermal conductivity of silicon-germanium alloys. The thermal conductivities of a series of epitaxially grown Si1-xGex thin films with varying thicknesses and compositions were measured with time-domain thermoreflectance. The resulting conductivities are found to be 3 to 5 times less than bulk values and vary strongly with film thickness. By examining these measured thermal conductivities in the context of a previously established model, it is shown that long wavelength phonons, known to be the dominant heat carriers in alloy films, are strongly scattered by the film boundaries, thereby inducing the observed reductions in heat transport. These results are then generalized to silicon-germanium systems of various thicknesses and compositions; we find that the thermal conductivities of Si1-xGex superlattices are ultimately limited by finite size effects and sample size rather than periodicity or alloying. This demonstrates the strong influence of sample size in alloyed nanosystems. Therefore, if a comparison is to be made between the thermal conductivities of superlattices and alloys, the total sample thicknesses of each must be considered.

  18. Gas Phase Pressure Effects on the Apparent Thermal Conductivity of JSC-1A Lunar Regolith Simulant

    Science.gov (United States)

    Yuan, Zeng-Guang; Kleinhenz, Julie E.

    2011-01-01

    Gas phase pressure effects on the apparent thermal conductivity of a JSC-1A/air mixture have been experimentally investigated under steady state thermal conditions from 10 kPa to 100 kPa. The result showed that apparent thermal conductivity of the JSC-1A/air mixture decreased when pressure was lowered to 80 kPa. At 10 kPa, the conductivity decreased to 0.145 W/m/degree C, which is significantly lower than 0.196 W/m/degree C at 100 kPa. This finding is consistent with the results of previous researchers. The reduction of the apparent thermal conductivity at low pressures is ascribed to the Knudsen effect. Since the characteristic length of the void space in bulk JSC-1A varies over a wide range, both the Knudsen regime and continuum regime can coexist in the pore space. The volume ratio of the two regimes varies with pressure. Thus, as gas pressure decreases, the gas volume controlled by Knudsen regime increases. Under Knudsen regime the resistance to the heat flow is higher than that in the continuum regime, resulting in the observed pressure dependency of the apparent thermal conductivity.

  19. Effective Thermal Conductivity of Open Cell Polyurethane Foam Based on the Fractal Theory

    Directory of Open Access Journals (Sweden)

    Kan Ankang

    2013-01-01

    Full Text Available Based on the fractal theory, the geometric structure inside an open cell polyurethane foam, which is widely used as adiabatic material, is illustrated. A simplified cell fractal model is created. In the model, the method of calculating the equivalent thermal conductivity of the porous foam is described and the fractal dimension is calculated. The mathematical formulas for the fractal equivalent thermal conductivity combined with gas and solid phase, for heat radiation equivalent thermal conductivity and for the total thermal conductivity, are deduced. However, the total effective heat flux is the summation of the heat conduction by the solid phase and the gas in pores, the radiation, and the convection between gas and solid phase. Fractal mathematical equation of effective thermal conductivity is derived with fractal dimension and vacancy porosity in the cell body. The calculated results have good agreement with the experimental data, and the difference is less than 5%. The main influencing factors are summarized. The research work is useful for the enhancement of adiabatic performance of foam materials and development of new materials.

  20. Thermal effect analysis of silicon microring optical switch for on-chip interconnect

    Science.gov (United States)

    Fang, Xiongfeng; Yang, Lin

    2017-10-01

    The silicon microring resonator plays an important role in large-scale, high-integrability modern switching matrixes and optical networks, as silicon photonics enables ring resonators of an unprecedented compact size. But as the nature of resonators is their sensitivity to temperature, their performances are vulnerable to being affected by thermal effect. In this paper, we analyze the dominant thermal effects to the application of silicon microring optical switch. On the one hand we theoretically analyze and experimentally measure the thermal crosstalk among adjacent microring optical switches with different distances, and give possible solutions to minimize the affect of thermal crosstalk. On the other hand we analyze and measure the thermooptic dynamic response of microring switch; the experiment shows for the thermal-tuning that the rising edge is around 2 μs, and the falling edge is around 35 μs. We give the explanation of the asymmetric rise-time and fall-time. Project supported by the Natural National Science Foundation of China (Nos. 61235001, 61575187, 61535002).

  1. Magneto-Seebeck effect in spin-valve with in-plane thermal gradient

    OpenAIRE

    S. Jain; D. D. Lam; A. Bose; H. Sharma; V. R. Palkar; C. V. Tomy; Y. Suzuki; A. A. Tulapurkar

    2014-01-01

    We present measurements of magneto-Seebeck effect on a spin valve with in-plane thermal gradient. We measured open circuit voltage and short circuit current by applying a temperature gradient across a spin valve stack, where one of the ferromagnetic layers is pinned. We found a clear hysteresis in these two quantities as a function of magnetic field. From these measurements, the magneto-Seebeck effect was found to be same as magneto-resistance effect.

  2. Magneto-Seebeck effect in spin-valve with in-plane thermal gradient

    Directory of Open Access Journals (Sweden)

    S. Jain

    2014-12-01

    Full Text Available We present measurements of magneto-Seebeck effect on a spin valve with in-plane thermal gradient. We measured open circuit voltage and short circuit current by applying a temperature gradient across a spin valve stack, where one of the ferromagnetic layers is pinned. We found a clear hysteresis in these two quantities as a function of magnetic field. From these measurements, the magneto-Seebeck effect was found to be same as magneto-resistance effect.

  3. Effect of Nanoparticles on the Morphology, Thermal, and Electrical Properties of Low-Density Polyethylene after Thermal Aging

    Directory of Open Access Journals (Sweden)

    Youyuan Wang

    2017-10-01

    Full Text Available This paper investigates the morphology, thermal, and electrical properties of LDPE (low-density polyethylene-based nanocomposites after thermal aging. The FTIR (Fourier transform infrared spectroscopy spectra results show that thermo-oxidative reactions occur in neat LDPE and LDPE/SiO2 nanocomposites when the aging time is 35 days and in LDPE/MgO nanocomposites when the aging time is 77 days. Specifically, LDPE/MgO nanocomposites delay the appearance of thermo-oxidative reactions, showing anti-thermal aging ability. Furthermore, nanocomposites present lower onset degradation temperature than neat LDPE, showing better thermal stabilization. With regard to the electrical properties, nanocomposites maintain the ability to suppress space charge accumulation after thermal aging. Additionally, in comparison with SiO2 nanocomposites and neat LDPE, the permittivity of LDPE/MgO nanocomposites changes slightly after thermal aging. It is concluded that LDPE/MgO nanocomposites have better insulation properties than neat LDPE after thermal aging, which may be caused by the interface introduced by the nanoparticles.

  4. Effect of Nanoparticles on the Morphology, Thermal, and Electrical Properties of Low-Density Polyethylene after Thermal Aging.

    Science.gov (United States)

    Wang, Youyuan; Wang, Can; Zhang, Zhanxi; Xiao, Kun

    2017-10-12

    This paper investigates the morphology, thermal, and electrical properties of LDPE (low-density polyethylene)-based nanocomposites after thermal aging. The FTIR (Fourier transform infrared spectroscopy) spectra results show that thermo-oxidative reactions occur in neat LDPE and LDPE/SiO₂ nanocomposites when the aging time is 35 days and in LDPE/MgO nanocomposites when the aging time is 77 days. Specifically, LDPE/MgO nanocomposites delay the appearance of thermo-oxidative reactions, showing anti-thermal aging ability. Furthermore, nanocomposites present lower onset degradation temperature than neat LDPE, showing better thermal stabilization. With regard to the electrical properties, nanocomposites maintain the ability to suppress space charge accumulation after thermal aging. Additionally, in comparison with SiO₂ nanocomposites and neat LDPE, the permittivity of LDPE/MgO nanocomposites changes slightly after thermal aging. It is concluded that LDPE/MgO nanocomposites have better insulation properties than neat LDPE after thermal aging, which may be caused by the interface introduced by the nanoparticles.

  5. Studying the Physical Basis of Global Warming: Thermal Effects of the Interaction between Radiation and Matter and Greenhouse Effect

    Science.gov (United States)

    Besson, Ugo; De Ambrosis, Anna; Mascheretti, Paolo

    2010-01-01

    We present a teaching module dealing with the thermal effects of interaction between radiation and matter, the infrared emission of bodies and the greenhouse effect devoted to university level and teacher education. The module stresses the dependence of the optical properties of materials (transparency, absorptivity and emissivity) on radiation…

  6. The Effect of Thermal Cycling Treatments on the Thermal Stability and Mechanical Properties of a Ti-Based Bulk Metallic Glass Composite

    Directory of Open Access Journals (Sweden)

    Fan Bu

    2016-11-01

    Full Text Available The effect of thermal cycling treatments on the thermal stability and mechanical properties of a Ti48Zr20Nb12Cu5Be15 bulk metallic glass composite (BMGC has been investigated. Results show that moderate thermal cycles in a temperature range of −196 °C (cryogenic temperature, CT to 25 °C (room temperature, RT or annealing time at CT has not induced obvious changes of thermal stability and then it decreases slightly over critical thermal parameters. In addition, the dendritic second phases with a bcc structure are homogeneously embedded in the amorphous matrix; no visible changes are detected, which shows structural stability. Excellent mechanical properties as high as 1599 MPa yield strength and 34% plastic strain are obtained, and the yield strength and elastic modulus also increase gradually. The effect on the stability is analyzed quantitatively by crystallization kinetics and plastic-flow models, and indicates that the reduction of structural relaxation enthalpy, which is related to the degradation of spatial heterogeneity, reduces thermal stability but does not imperatively deteriorate the plasticity.

  7. Mid-infrared thermal imaging for an effective mapping of surface materials and sub-surface detachments in mural paintings: integration of thermography and thermal quasi-reflectography

    Science.gov (United States)

    Daffara, C.; Parisotto, S.; Mariotti, P. I.

    2015-06-01

    Cultural Heritage is discovering how precious is thermal analysis as a tool to improve the restoration, thanks to its ability to inspect hidden details. In this work a novel dual mode imaging approach, based on the integration of thermography and thermal quasi-reflectography (TQR) in the mid-IR is demonstrated for an effective mapping of surface materials and of sub-surface detachments in mural painting. The tool was validated through a unique application: the "Monocromo" by Leonardo da Vinci in Italy. The dual mode acquisition provided two spatially aligned dataset: the TQR image and the thermal sequence. Main steps of the workflow included: 1) TQR analysis to map surface features and 2) to estimate the emissivity; 3) projection of the TQR frame on reference orthophoto and TQR mosaicking; 4) thermography analysis to map detachments; 5) use TQR to solve spatial referencing and mosaicking for the thermal-processed frames. Referencing of thermal images in the visible is a difficult aspect of the thermography technique that the dual mode approach allows to solve in effective way. We finally obtained the TQR and the thermal maps spatially referenced to the mural painting, thus providing the restorer a valuable tool for the restoration of the detachments.

  8. Effective versus ion thermal temperatures in the Weizmann Ne Z-pinch: Modeling and stagnation physics

    Energy Technology Data Exchange (ETDEWEB)

    Giuliani, J. L.; Thornhill, J. W.; Dasgupta, A.; Velikovich, A. L.; Chong, Y. K.; Mehlhorn, T. A. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Kroupp, E.; Osin, D.; Maron, Y.; Starobinets, A.; Fisher, V.; Zarnitsky, Yu.; Bernshtam, V. [Weizmann Institute of Science, Rehovot 76100 (Israel); Apruzese, J. P. [Consultant to NRL through Engility Corp., Chantilly, Virginia 20151 (United States); Fisher, A. [Falculty of Physics, Technion-Israeli Institute of Technology, Haifa (Israel); Deeney, C. [National Security Technologies, LLC, Las Vegas, Nevada 89144 (United States)

    2014-03-15

    The difference between the ion thermal and effective temperatures is investigated through simulations of the Ne gas puff z-pinch reported by Kroupp et al. [Phys. Rev. Lett. 107, 105001 (2011)]. Calculations are performed using a 2D, radiation-magnetohydrodynamic code with Tabular Collisional-Radiative Equilibrium, namely Mach2-TCRE [Thornhill et al., Phys. Plasmas 8, 3480 (2001)]. The extensive data set of imaging and K-shell spectroscopy from the experiments provides a challenging validation test for z-pinch simulations. Synthetic visible images of the implosion phase match the observed large scale structure if the breakdown occurs at the density corresponding to the Paschen minimum. At the beginning of stagnation (−4 ns), computed plasma conditions change rapidly showing a rising electron density and a peak in the ion thermal temperature of ∼1.8 keV. This is larger than the ion thermal temperature (<400 eV) inferred from the experiment. By the time of peak K-shell power (0 ns), the calculated electron density is similar to the data and the electron and ion thermal temperatures are equilibrated, as is observed. Effective ion temperatures are obtained from calculated emission line widths accounting for thermal broadening and Doppler velocity shifts. The observed, large effective ion temperatures (∼4 keV) early in the stagnation of this Ne pinch can be explained solely as a combination of compressional ion heating and steep radial velocity gradients near the axis. Approximations in the modeling are discussed in regard to the higher ion thermal temperature and lower electron density early in the stagnation compared to the experimental results.

  9. Comparison of KTP, Thulium, and CO2 laser in stapedotomy using specialized visualization techniques: thermal effects.

    Science.gov (United States)

    Kamalski, Digna M A; Verdaasdonk, Rudolf M; de Boorder, Tjeerd; Vincent, Robert; Trabelzini, Franco; Grolman, Wilko

    2014-06-01

    High-speed thermal imaging enables visualization of heating of the vestibule during laser-assisted stapedotomy, comparing KTP, CO2, and Thulium laser light. Perforation of the stapes footplate with laser bears the risk of heating of the inner ear fluids. The amount of heating depends on absorption of the laser light and subsequent tissue ablation. The ablation of the footplate is driven by strong water absorption for the CO2 and Thulium laser. For the KTP laser wavelength, ablation is driven by carbonization of the footplate and it might penetrate deep into the inner ear without absorption in water. The thermal effects were visualized in an inner ear model, using two new techniques: (1) high-speed Schlieren imaging shows relative dynamic changes of temperatures up to 2 ms resolution in the perilymph. (2) Thermo imaging provides absolute temperature measurements around the footplate up to 40 ms resolution. The high-speed Schlieren imaging showed minimal heating using the KTP laser. Both CO2 and Thulium laser showed heating below the footplate. Thulium laser wavelength generated heating up to 0.6 mm depth. This was confirmed with thermal imaging, showing a rise of temperature of 4.7 (±3.5) °C for KTP and 9.4 (±6.9) for Thulium in the area of 2 mm below the footplate. For stapedotomy, the Thulium and CO2 laser show more extended thermal effects compared to KTP. High-speed Schlieren imaging and thermal imaging are complimentary techniques to study lasers thermal effects in tissue.

  10. Thermal inertia of near-Earth asteroids and implications for the magnitude of the Yarkovsky effect

    NARCIS (Netherlands)

    Delbo', Marco; dell'Oro, Aldo; Harris, Alan W.; Mottola, Stefano; Mueller, Michael

    2007-01-01

    Thermal inertia determines the temperature distribution over the surface of an asteroid and therefore governs the magnitude the Yarkovsky effect. The latter causes gradual drifting of the orbits of km-sized asteroids and plays an important role in the delivery of near-Earth asteroids (NEAs) from the

  11. Thermal inertia of near-Earth asteroids and magnitude of the Yarkovsky effect

    NARCIS (Netherlands)

    Delbo, M.; Dell'Oro, A.; Harris, A. W.; Mottola, S.; Mueller, M.

    2006-01-01

    Thermal inertia of near-Earth asteroids and magnitude of the Yarkovsky effect M. Delbo* (1,2), A. Dell'Oro (2), A. W. Harris (3), S. Mottola (3), M. Mueller (3) (1) Observatoire de la Côte d'Azur B.P. 4229, 06034 Nice Cedex 4, France. (2) INAF-Osservatorio Astr. di Torino, via Osservatorio 20, 10025

  12. Thermal Inertia of near-Earth Asteroids and Strength of the Yarkovsky Effect

    NARCIS (Netherlands)

    Delbo, Marco; Dell'Oro, A.; Harris, A. W.; Mottola, S.; Mueller, M.

    2006-01-01

    Thermal inertia is the physical parameter that controls the temperature distribution over the surface of an asteroid. It affects the strength of the Yarkovsky effect, which causes orbital drift of km-sized asteroids and is invoked to explain the delivery of near-Earth asteroids (NEAs) from the main

  13. Effects of flow and colony morphology on the thermal boundary layer of corals

    DEFF Research Database (Denmark)

    Jimenez, Isabel M; Kühl, Michael; Larkum, Anthony W D

    2011-01-01

    . The effect of water flow on the thermal microenvironment was investigated in hemispherical and branching corals (Porites lobata and Stylophora pistillata, respectively) in a flow chamber experiment. For both coral types, the thickness of the TBL decreased exponentially from 2.5 mm at quasi-stagnant flow (0...

  14. Planck 2015 results: XXII. A map of the thermal Sunyaev-Zeldovich effect

    DEFF Research Database (Denmark)

    Aghanim, N.; Arnaud, M.; Ashdown, M.

    2016-01-01

    We have constructed all-sky Compton parameters maps, y-maps, of the thermal Sunyaev-Zeldovich (tSZ) effect by applying specifically tailored component separation algorithms to the 30 to 857 GHz frequency channel maps from the Planck satellite. These reconstructed y-maps are delivered as part of t...

  15. Tuning the effective coupling of an AFM lever to a thermal bath

    Energy Technology Data Exchange (ETDEWEB)

    Jourdan, G [Institut Neel CNRS Grenoble BP 166 38042, Grenoble Cedex 9 (France); Torricelli, G [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Chevrier, J [Institut Neel CNRS Grenoble BP 166 38042, Grenoble Cedex 9 (France); Comin, F [ESRF, 6 rue Jules Horowitz, BP220, 38043 Grenoble Cedex (France)

    2007-11-28

    Fabrication of high quality nano-electromechanical systems (NEMS) is nowadays extremely efficient. These NEMS will be used as sensors and actuators in integrated systems. Their use, however, raises questions about their interface (actuation, detection, read out) with external detection and control systems. Their operation implies many fundamental questions related to single particle effects such as Coulomb blockade, light matter interactions such as radiation pressure, thermal effects, Casimir forces and the coupling of nanosystems to the external world (thermal fluctuations, back action effect). Here we specifically present how the damping of an oscillating cantilever can be tuned in two radically different ways: (i) through an electromechanical coupling in the presence of a strong Johnson noise, (ii) through an external feedback control of thermal fluctuations which is the cold damping closely related to Maxwell's demon. This shows how the interplay between external control of micro-EMS (MEMS) or NEMS and their coupling to a thermal bath can lead to a wealth of effects that are nowadays extensively studied in different areas.

  16. The effects of permafrost thaw on soil hydrologic, thermal, and carbon dynamics in an Alaskan peatland

    Science.gov (United States)

    Jonathan A. O' Donnell; M.Torre Jorgenson; Jennifer W. Harden; A.David McGuire; Mikhail Z. Kanevskiy; Kimberly P. Wickland

    2012-01-01

    Recent warming at high-latitudes has accelerated permafrost thaw in northern peatlands, and thaw can have profound effects on local hydrology and ecosystem carbon balance. To assess the impact of permafrost thaw on soil organic carbon (OC) dynamics, we measured soil hydrologic and thermal dynamics and soil OC stocks across a collapse-scar bog chronosequence in interior...

  17. Upgrading Fast Pyrolysis Oil via Hydrodeoxygenation and Thermal Treatment: Effects of Catalytic Glycerol Pretreatment

    NARCIS (Netherlands)

    Reyhanitash, Ehsan; Tymchyshyn, M.; Yuan, Zhongshun; Albion, K.; van Rossum, G.; Xu, C.

    2014-01-01

    The effects of stabilizing fast pyrolysis oil (PO) with glycerol via catalytic glycerol pretreatment on upgrading via hydrodeoxygenation (HDO) or thermal treatment (TT) were studied. Nonstabilized (original) fast pyrolysis oil was also upgraded via HDO or TT to obtain benchmarks. Generally, HDO

  18. Effect of magnesium aluminum silicate glass on the thermal shock resistance of BN matrix composite ceramics

    NARCIS (Netherlands)

    Cai, Delong; Jia, Dechang; Yang, Zhihua; Zhu, Qishuai; Ocelik, Vaclav; Vainchtein, Ilia D.; De Hosson, Jeff Th M.; Zhou, Yu

    The effects of magnesium aluminum silicate (MAS) glass on the thermal shock resistance and the oxidation behavior of h-BN matrix composites were systematically investigated at temperature differences from 600 degrees C up to 1400 degrees C. The retained strength rate of the composites rose with the

  19. The Effect of Ethylene Glycol, Glycine Betaine, and Urea on Lysozyme Thermal Stability

    Science.gov (United States)

    Schwinefus, Jeffrey J.; Leslie, Elizabeth J.; Nordstrom, Anna R.

    2010-01-01

    The four-week student project described in this article is an extension of protein thermal denaturation experiments to include effects of added cosolutes ethylene glycol, glycine betaine, and urea on the unfolding of lysozyme. The transition temperatures and van't Hoff enthalpies for unfolding are evaluated for six concentrations of each cosolute,…

  20. Humidity Effects on Soluble Core Mechanical and Thermal Properties (Polyvinyl Alcohol/Microballoon Composite)

    Science.gov (United States)

    1993-01-01

    This document constitutes the final report for the study of humidity effects and loading rate on soluble core (PVA/MB composite material) mechanical and thermal properties. This report describes test results, procedures employed, and any unusual occurrences or specific observations associated with this test program.

  1. Effective and efficient agricultural drainage pipe mapping with UAS thermal infrared imagery: a case study

    Science.gov (United States)

    Effective and efficient methods are needed to map agricultural subsurface drainage systems. Visible (VIS), near infrared (NIR), and/or thermal infrared (TIR) imagery obtained by unmanned aircraft systems (UAS) may provide a means for determining drainage pipe locations. Preliminary UAS surveys wit...

  2. Effects of microwave heating on the thermal states of biological tissues

    African Journals Online (AJOL)

    Effects of microwave heating on the thermal states of biological tissues. Nabil TM El-dabe, Mona AA Mohamed, Asma F El-Sayed. Abstract. A mathematical analysis of microwave heating equations in one-dimensional multi-layer model has been discussed. Maxwell's equations and transient bioheat transfer equation were ...

  3. Mechanical and thermal cycling effects on the flexural strength of glass ceramics fused to titanium

    NARCIS (Netherlands)

    Vasquez, Vanessa; Ozcan, Mutlu; Nishioka, Renato; Souza, Rodrigo; Mesquita, Alfredo; Pavanelli, Carlos

    This study evaluated the effects of mechanical and thermal cycling on the flexural strength (ISO 9693) of three brands of ceramics fused to commercially pure titanium (cpTi). Metallic frameworks of 25 x 3 x 0.5 mm dimensions (N = 84) were cast in cpTi, followed by 150-mu m aluminum oxide airborne

  4. The effect of thermal contact resistance on the thermosetting pultrusion process

    DEFF Research Database (Denmark)

    Baran, Ismet; Tutum, Cem Celal; Hattel, Jesper Henri

    2013-01-01

    experimentally in the literature. In order to study the effects of the thermal contact resistance (TCR), which can also be expressed by the heat transfer coefficient (HTC), on the pultrusion process, a cylindrical die block and heaters are added to the original problem domain. The significance of using the TCR...

  5. Effect of pre-heating on the thermal decomposition kinetics of cotton

    Science.gov (United States)

    The effect of pre-heating at low temperatures (160-280°C) on the thermal decomposition kinetics of scoured cotton fabrics was investigated by thermogravimetric analysis under nonisothermal conditions. Isoconversional methods were used to calculate the activation energies for the pyrolysis after one-...

  6. Effect of pMDI isocyanate additive on mechanical and thermal ...

    Indian Academy of Sciences (India)

    Abstract. The effect of polymeric methylene diphenyl diisocyanate (pMDI) on mechanical and thermal properties of Kenaf fibre (KF) reinforced thermoplastic polyurethane (TPU) composites was studied. Various percentages viz. 2%, 4% and 6%, were studied. The composites were characterized by using tensile testing, ...

  7. Effect of particle size on thermal decomposition of alkali metal picrates

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Rui; Zhang, Tonglai, E-mail: ztlbit@bit.edu.cn; Yang, Li; Zhou, Zunning

    2014-05-01

    Graphical abstract: The smaller-sized picrate has greater gas emission than do its larger counterpart. The small size effect reduces the thermal decomposition activation energy, accelerates the reaction rate, and promotes the reaction activity. - Highlights: • Picrates were prepared into three micron sizes by microemulsion synthesis. • Thermal decomposition kinetics and thermodynamics were studied by DPTA and DSC. • Smaller-sized picrate has higher activity and faster reaction rate. • Particle size effect on thermal decomposition kinetics and thermodynamics was revealed. - Abstract: Three alkali metal picrates, KPA, RbPA and CsPA, were prepared into three micron sizes by microemulsion synthesis, and their thermal decomposition behaviors were investigated by DPTA at different temperatures and by DSC at different heating rates. The smaller-sized picrate has greater gas emission and smaller kinetic and thermodynamic parameters than do its larger counterpart. It can be attributed to the decreasing particle size which leads to the high surface energy, the fast mass and heat transfer, and the increasing active sites on the reaction interface. The small size effect and surface effect cause the autocatalysis which reduces the activation energy and promotes the reaction activity. The particle size does not affect the reaction mechanism. However, the picrates with different central alkali metals exhibit different reaction mechanisms even though they are of the same size. This is because the central metal determines the bond energy and consequently affects the stability of picrate.

  8. Effective thermal/mechanical properties of honeycomb core panels for hot structure applications

    NARCIS (Netherlands)

    Fatemi, J.; Lemmen, M.H.J.

    2009-01-01

    The present work addresses the computation of the effective thermal and mechanical properties of a honeycombcore sandwich panel. The panel considered has a hexagon-cell honeycomb core. An alternative method, based on the Gebhart factors within a hexagonal cell, is presented in addition to the

  9. Effect of Hydration State of Martian Perchlorate Salts on Their Decomposition Temperatures During Thermal Extraction

    Science.gov (United States)

    Royle, Samuel H.; Montgomery, Wren; Kounaves, Samuel P.; Sephton, Mark A.

    2017-12-01

    Three Mars missions have analyzed the composition of surface samples using thermal extraction techniques. The temperatures of decomposition have been used as diagnostic information for the materials present. One compound of great current interest is perchlorate, a relatively recently discovered component of Mars' surface geochemistry that leads to deleterious effects on organic matter during thermal extraction. Knowledge of the thermal decomposition behavior of perchlorate salts is essential for mineral identification and possible avoidance of confounding interactions with organic matter. We have performed a series of experiments which reveal that the hydration state of magnesium perchlorate has a significant effect on decomposition temperature, with differing temperature releases of oxygen corresponding to different perchlorate hydration states (peak of O2 release shifts from 500 to 600°C as the proportion of the tetrahydrate form in the sample increases). Changes in crystallinity/crystal size may also have a secondary effect on the temperature of decomposition, and although these surface effects appear to be minor for our samples, further investigation may be warranted. A less than full appreciation of the hydration state of perchlorate salts during thermal extraction analyses could lead to misidentification of the number and the nature of perchlorate phases present.

  10. Effect of thermal ammoniation and heat treatment on the faecal and ...

    African Journals Online (AJOL)

    Polyphenol content was reduced from 1,24 to 0,55%. This study was therefore conducted to determine the effect of thermal ammoniation and heat treatment of ... high-tannin grain in the diet on the performance of growing pigs. Experimental Procedures. Digestion trial. Grain sorghum with a polyphenol content of 1,24%.

  11. effect of thermal stress of short duration on the red blood cell

    African Journals Online (AJOL)

    Dr Ivanc

    2013-05-01

    May 1, 2013 ... surrounding environment dictates the body temperature and fish become vulnerable to unseasonal thermal changes that may occur. Acute temperature increases have been found to initiate primary as well as secondary stress response, both of which produce osmoregulatory and metabolic effects in many ...

  12. Two-dimensional finite element heat transfer model of softwood. Part I, Effective thermal conductivity

    Science.gov (United States)

    John F. Hunt; Hongmei Gu

    2006-01-01

    The anisotropy of wood complicates solution of heat and mass transfer problems that require analyses be based on fundamental material properties of the wood structure. Most heat transfer models use average thermal properties across either the radial or tangential direction and do not differentiate the effects of cellular alignment, earlywood/latewood differences, or...

  13. Effect of thermal treatment on apatite-forming ability of NaOH-treated tantalum metal.

    Science.gov (United States)

    Miyazaki, T; Kim, H M; Kokubo, T; Miyaji, F; Kato, H; Nakamura, T

    2001-08-01

    The prerequisite for an artificial material to bond to living bone is the formation of bonelike apatite on its surface in the body. This apatite can be reproduced on its surface even in an acellular simulated body fluid with ion concentrations nearly equal to those of the human blood plasma. The present authors previously showed that the tantalum metal subjected to a NaOH treatment to form a sodium tantalate hydrogel layer on its surface forms the bonelike apatite on its surface in SBF in a short period. The gel layer as-formed on the metal is, however, not resistant against abrasion, and hence thus-treated metal is not useful for clinical applications. In the present study, effects of thermal treatment on the mechanical properties and apatite-forming ability of the NaOH-treated tantalum metal were investigated. The sodium tantalate gel on the NaOH-treated tantalum was dehydrated to convert into amorphous sodium tantalate by a thermal treatment at 300 degrees C in air environment and into crystalline sodium tantalates by the thermal treatment at 500 degrees C. Resistivity of the gel layer against both peeling-off and scratching was significantly improved by the thermal treatment at 300 degrees C. The high apatite-forming ability of the sodium tantalate hydrogel was a little decreased by the thermal treatment at 300 degrees C, but appreciably decreased by the thermal treatment at 500 degrees C. It is believed that the tantalum metal subjected to the 0.5 M-NaOH treatment and the subsequent thermal treatment at 300 degrees C is useful as implants in dental and orthopaedic fields, since it shows high bioactivity as well as high fracture toughness. Copyright 2001 Kluwer Academic Publishers

  14. Effect of posture positions on the evaporative resistance and thermal insulation of clothing.

    Science.gov (United States)

    Wu, Y S; Fan, J T; Yu, W

    2011-03-01

    Evaporative resistance and thermal insulation of clothing are important parameters in the design and engineering of thermal environments and functional clothing. Past work on the measurement of evaporative resistance of clothing was, however, limited to the standing posture with or without body motion. Information on the evaporative resistance of clothing when the wearer is in a sedentary or supine posture and how it is related to that when the wearer is in a standing posture is lacking. This paper presents original data on the effect of postures on the evaporative resistance of clothing, thermal insulation and permeability index, based on the measurements under three postures, viz. standing, sedentary and supine, using the sweating fabric manikin-Walter. Regression models are also established to relate the evaporative resistance and thermal insulation of clothing under sedentary and supine postures to those under the standing posture. The study further shows that the apparent evaporated resistances of standing and sedentary postures measured in the non-isothermal condition are much lower than those in the isothermal condition. The apparent evaporative resistances measured using the mass loss method are generally lower than those measured using the heat loss method due to moisture absorption or condensation within clothing. STATEMENT OF RELEVANCE: The thermal insulation and evaporative resistance values of clothing ensembles under different postures are essential data for the ergonomics design of thermal environments (e.g. indoors or a vehicle's interior environment) and functional clothing. They are also necessary for the prediction of thermal comfort or duration of exposure in different environmental conditions.

  15. Anomalous strain effect on the thermal conductivity of borophene: a reactive molecular dynamics study

    Science.gov (United States)

    Mortazavi, Bohayra; Le, Minh-Quy; Rabczuk, Timon; Pereira, Luiz Felipe C.

    2017-09-01

    Borophene, an atomically thin, corrugated, crystalline two-dimensional boron sheet, has been recently synthesized. Here we investigate mechanical properties and lattice thermal conductivity of borophene using reactive molecular dynamics simulations. We performed uniaxial tensile strain simulations at room temperature along in-plane directions, and found 2D elastic moduli of 188 N m-1 and 403 N m-1 along zigzag and armchair directions, respectively. This anisotropy is attributed to the buckling of the borophene structure along the zigzag direction. We also performed non-equilibrium molecular dynamics to calculate the lattice thermal conductivity. Considering its size-dependence, we predict room-temperature lattice thermal conductivities of 75.9 ± 5.0 W m-1 K-1 and 147 ± 7.3 W m-1 K-1, respectively, and estimate effective phonon mean free paths of 16.7 ± 1.7 nm and 21.4 ± 1.0 nm for the zigzag and armchair directions. In this case, the anisotropy is attributed to differences in the density of states of low-frequency phonons, with lower group velocities and possibly shorten phonon lifetimes along the zigzag direction. We also observe that when borophene is strained along the armchair direction there is a significant increase in thermal conductivity along that direction. Meanwhile, when the sample is strained along the zigzag direction there is a much smaller increase in thermal conductivity along that direction. For a strain of 8% along the armchair direction the thermal conductivity increases by a factor of 3.5 (250%), whereas for the same amount of strain along the zigzag direction the increase is only by a factor of 1.2 (20%). Our predictions are in agreement with recent first principles results, at a fraction of the computational cost. The simulations shall serve as a guide for experiments concerning mechanical and thermal properties of borophene and related 2D materials.

  16. Weathering of coil-coatings: UV radiation and thermal effects

    Directory of Open Access Journals (Sweden)

    Castela, A. S.

    2003-12-01

    Full Text Available The effect of heat and of QUV ageing on coil coatings was tested by electrochemical impedance, and the results compared with surface analysis of the polymers by FTIR and XPS. It was shown that UV radiation is more relevant than heat to chemical degradation. A different correlation between water permeation and chemical degradation was observed depending on the coating thickness: for the thinner coatings, the higher UV degradation has corresponded to increased water absorption, whereas in the thicker coating, the bulk effect of heat was more relevant to water permeation.

    El efecto del calor y del envejecimiento, QUV, sobre recubrimiemtos de bobinas se probó mediante la impedancia electroquímica, y los resultados se compararon con análisis superficiales de los polímeros usando FTIR y XPS. Se encontró que la radiación UV es más importante que el calor en la degradación química. Una correlación diferente, entre agua infiltrada y degradación química, se observó, dependiendo del espesor del recubrimiento: para los recubrimientos más delgados, mayor degradación UV correspondió a un incremento de absorción de agua; en cambio, para los recubrimientos más gruesos, el efecto del calor fue más importante para la infiltración del agua.

  17. Hall Effect on Thermal Instability of Viscoelastic Dusty Fluid in Porous Medium

    Science.gov (United States)

    Singh, M.; Gupta, R. K.

    2013-08-01

    The effect of Hall currents and suspended dusty particles on the hydromagnetic stability of a compressible, electrically conducting Rivlin-Ericksen elastico viscous fluid in a porous medium is considered. Following the linearized stability theory and normal mode analysis the dispersion relation is obtained. For the case of stationary convection, Hall currents and suspended particles are found to have destabilizing effects whereas compressibility and magnetic field have stabilizing effects on the system. The medium permeability, however, has stabilizing and destabilizing effects on thermal instability in contrast to its destabilizing effect in the absence of the magnetic field. The critical Rayleigh numbers and the wave numbers of the associated disturbances for the onset of instability as stationary convection are obtained and the behavior of various parameters on critical thermal Rayleigh numbers are depicted graphically. The magnetic field, Hall currents and viscoelasticity parameter are found to introduce oscillatory modes in the systems, which did not exist in the absence of these parameters

  18. Thermal conductivity prediction of closed-cell aluminum alloy considering micropore effect

    Directory of Open Access Journals (Sweden)

    Donghui Zhang

    2015-02-01

    Full Text Available Large quantities of micro-scale pores are observed in the matrix of closed-cell aluminum alloy by scanning electron microscope, which indicates the dual-scale pore characteristics. Corresponding to this kind of special structural morphology, a new kind of dual-scale method is proposed to estimate its effective thermal conductivity. Comparing with the experimental results, the article puts forward the view that the prediction accuracy can be improved by the dual-scale method greatly. Different empirical formulas are also investigated in detail. It provides a new method for thermal properties estimation and makes preparation for more suitable empirical formula for closed-cell aluminum alloy.

  19. Numerical Study of Thermal Radiation Effect on Confined Turbulent Free Triangular Jets

    Directory of Open Access Journals (Sweden)

    Kiyan Parham

    2013-01-01

    Full Text Available The present study investigates the effects of thermal radiation on turbulent free triangular jets. Finite volume method is applied for solving mass, momentum, and energy equations simultaneously. Discrete ordinate method is used to determine radiation transfer equation (RTE. Results are presented in terms of velocity, kinetic energy, and its dissipation rate fields. Results show that thermal radiation speeds the development of velocity on the jet axis and enhances kinetic energy; therefore, when radiation is added to free jet its mixing power, due to extra kinetic energy, increases.

  20. Effects of thermal shocks on the release of radioisotopes and on molten metal target vessels

    CERN Document Server

    Lettry, Jacques; Benedikt, Michael; Catherall, R; Cyvoct, G; Fabich, A; Georg, U; Gilardoni, S S; Jonsson, O; Ravn, H L; Sgobba, Stefano; Bauer, G; Bruchertseifer, H; Graber, T; Gudermann, C; Ni, L; Rastani, R

    2003-01-01

    The ISOLDE pulsed proton beam peak power amounts to 500 MW during the 2.4 ms proton pulse. The fraction of the proton pulse energy deposited in the target material is at the origin of severe thermal shocks. Quantitative measurement of their effect on the release of radioelements from ISOLDE targets was obtained by comparison of release profiles measured under different proton beam settings. The thermal shock induced in liquids (Pb, Sn, La) lead to mechanical failure of ISOLDE molten metal target vessels. Failure analysis is presented and discussed in the light of the response of mercury samples submitted to the ISOLDE beam and monitored by high-speed optical systems.

  1. Evaluation of non-thermal plasma-induced anticancer effects on human colon cancer cells

    Science.gov (United States)

    Choi, Jae-Sun; Kim, Jeongho; Hong, Young-Jun; Bae, Woom-Yee; Choi, Eun Ha; Jeong, Joo-Won; Park, Hun-Kuk

    2017-01-01

    Non-thermal atmospheric-pressure plasma has been introduced in various applications such as sterilization, wound healing, blood coagulation, and other biomedical applications. The most attractive application of non-thermal atmospheric-pressure plasma is in cancer treatment, where the plasma is used to produce reactive oxygen species (ROS) to facilitate cell apoptosis. We investigate the effects of different durations of exposure to dielectric-barrier discharge (DBD) plasma on colon cancer cells using measurement of cell viability and ROS levels, western blot, immunocytochemistry, and Raman spectroscopy. Our results suggest that different kinds of plasma-treated cells can be differentiated from control cells using the Raman data. PMID:28663896

  2. Effects of Thermal Exposure on Properties of Al-Li Alloys

    Science.gov (United States)

    Shah, Sandeep; Wells, Doug; Stanton, William; Lawless, Kirby; Russell, Carolyn; Wagner, John; Domack, Marcia; Babel, Henry; Farahmand, Bahram; Schwab, David; hide

    2002-01-01

    This paper presents viewgraphs on the effects of thermal exposure on the mechanical properties of both developmental and production mature Al-Li alloys. The topics include: 1) Aluminum-Lithium Alloys Composition and Features; 2) Key Characteristics of Al-Li Alloys; 3) Research Approach; 4) Available and Tested Material; and 5) Thermal Exposure Matrix. The alloy temperatures, gage thickness and product forms show that there is no deficit in mechanical properties at lower exposure temperatures in some cases, and a significant deficit in mechanical properties at higher exposure temperatures in all cases.

  3. 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....

  4. Topical glucocorticoid has no antinociceptive or anti-inflammatory effect in thermal injury

    DEFF Research Database (Denmark)

    Pedersen, J L; Møiniche, S; Kehlet, H

    1994-01-01

    injuries were induced with a thermode, which was heated to 49 degrees C for 5 min under standardized pressure. Clobetasol propionate or placebo cream was applied to the skin 1 h before burn injury, immediately after the injury and every 12 h for the next 3 days. Heat pain detection thresholds (HPDT), heat......We have studied the antinociceptive and anti-inflammatory effects of topical glucocorticoids in human thermal injury. The right and left legs of 12 healthy volunteers were allocated randomly to be treated with either 0.05% clobetasol propionate cream or placebo in a double-blind trial. Thermal...

  5. Effect of Air Plasma Treatment on Thermal Comfort Properties of Woven Fabric

    Science.gov (United States)

    Rajwin, A. Jebastin; Prakash, C.

    2017-11-01

    In this study, the effect of air plasma on thermal comfort properties of cotton woven fabric has been investigated. The woven fabric samples were treated with plasma under various parameters like treatment time, the distance between fabric sample and electrode, and frequency of the plasma process. It was observed that air permeability of the fabric has a linear relationship with distance of the sample, and inversely related to time and frequency. The thermal resistance and water vapor permeability decreased with distance and increased with time and frequency.

  6. Effects of LDEF flight exposure on selected polymeric films and thermal control coatings

    Science.gov (United States)

    Slemp, Wayne S.; Young, Philip R.; Shen, James Y.

    1991-01-01

    The characterization of polymeric films and thermal control coatings which were exposed for five years and ten months to the low-Earth environment is reported. Changes in solar absorptance, thermal emittance, and transmission are compared to laboratory control specimens. Sputter-deposited metallic coatings are shown to eliminate atomic oxygen erosion of resin matrix composite materials. The effects of long-term atomic oxygen exposure to metallized FEP Teflon film is characterized. Chemical characterization of polymeric films indicates that although surface erosion occurs, the molecular structure of the basic polymeric film has not changed significantly in response to this exposure.

  7. Combined effect of magnetic field and thermal dispersion on a non-darcy mixed convection

    KAUST Repository

    El-Amin, Mohamed

    2011-05-21

    This paper is devoted to investigate the influences of thermal dispersion and magnetic field on a hot semi-infinite vertical porous plate embedded in a saturated Darcy-Forchheimer-Brinkman porous medium. The coefficient of thermal diffusivity has been assumed to be the sum of the molecular diffusivity and the dynamic diffusivity due to mechanical dispersion. The effects of transverse magnetic field parameter (Hartmann number Ha), Reynolds number Re (different velocities), Prandtl number Pr (different types of fluids) and dispersion parameter on the wall shear stress and the heat transfer rate are discussed. © 2011 Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag Berlin Heidelberg.

  8. Effects of Thermal Cycling on Control and Irradiated EPC 2nd Generation GaN FETs

    Science.gov (United States)

    Patterson, Richard L.; Scheick, Leif; Lauenstein, Jean-Marie; Casey, Megan; Hammoud, Ahmad

    2013-01-01

    The power systems for use in NASA space missions must work reliably under harsh conditions including radiation, thermal cycling, and exposure to extreme temperatures. Gallium nitride semiconductors show great promise, but information pertaining to their performance is scarce. Gallium nitride N-channel enhancement-mode field effect transistors made by EPC Corporation in a 2nd generation of manufacturing were exposed to radiation followed by long-term thermal cycling in order to address their reliability for use in space missions. Results of the experimental work are presented and discussed.

  9. Evaluation of thermal effects and strain-rate sensitivity in frozen soil

    Directory of Open Access Journals (Sweden)

    Zhu Zhi-Wu

    2014-01-01

    Full Text Available Temperature variation is one important factor that affects the dynamic mechanical properties of frozen soil under impact loading. Thermal damage is a collective phenomenon that can be caused by temperature variation. This paper investigates the effects of thermal damage on strain course. A split Hopkinson pressure bar was employed to investigate the dynamic mechanical characteristics of frozen soil at different temperatures and different strain rates. The stress-strain curves were obtained under impact loading. The compressive strength of frozen soil showed a negative temperature sensitivity and positive strain-rate trend. Specifically, the strength of frozen soil increased with decreasing temperatures and increasing strain rates.

  10. Clothing resultant thermal insulation determined on a movable thermal manikin. Part II: effects of wind and body movement on local insulation.

    Science.gov (United States)

    Lu, Yehu; Wang, Faming; Wan, Xianfu; Song, Guowen; Zhang, Chengjiao; Shi, Wen

    2015-10-01

    Part II of this two-part series study was focused on examining the effects of wind and body movement on local clothing thermal insulation. Seventeen clothing ensembles with different layers (i.e., 1, 2, or 3 layers) were selected for this study. Local thermal insulation with different air velocities (0.15, 1.55, and 4.0 m/s) and walking speeds (0, 0.75, and 1.17 m/s) were investigated on a thermal manikin. Empirical equations for estimating local resultant clothing insulation as a function of local insulation, air velocity, and walking speed were developed. The results showed that the effects of wind and body movement on local resultant thermal resistance are complex and differ distinctively among different body parts. In general, the reductions of local insulation with wind at the chest, abdomen, and pelvis were greater than those at the lower leg and back, and the changes at the body extremity such as the forearm, thigh, and lower leg were higher than such immobile body parts as the chest and back. In addition, the wind effect interacted with the walking effect. This study may have important applications in human local thermal comfort modeling and functional clothing design.

  11. Thermal phase transition with full 2-loop effective potential

    Science.gov (United States)

    Laine, M.; Meyer, M.; Nardini, G.

    2017-07-01

    Theories with extended Higgs sectors constructed in view of cosmological ramifications (gravitational wave signal, baryogenesis, dark matter) are often faced with conflicting requirements for their couplings; in particular those influencing the strength of a phase transition may be large. Large couplings compromise perturbative studies, as well as the high-temperature expansion that is invoked in dimensionally reduced lattice investigations. With the example of the inert doublet extension of the Standard Model (IDM), we show how a resummed 2-loop effective potential can be computed without a high-T expansion, and use the result to scrutinize its accuracy. With the exception of Tc, which is sensitive to contributions from heavy modes, the high-T expansion is found to perform well. 2-loop corrections weaken the transition in IDM, but they are moderate, whereby a strong transition remains an option.

  12. Thermal phase transition with full 2-loop effective potential

    Directory of Open Access Journals (Sweden)

    M. Laine

    2017-07-01

    Full Text Available Theories with extended Higgs sectors constructed in view of cosmological ramifications (gravitational wave signal, baryogenesis, dark matter are often faced with conflicting requirements for their couplings; in particular those influencing the strength of a phase transition may be large. Large couplings compromise perturbative studies, as well as the high-temperature expansion that is invoked in dimensionally reduced lattice investigations. With the example of the inert doublet extension of the Standard Model (IDM, we show how a resummed 2-loop effective potential can be computed without a high-T expansion, and use the result to scrutinize its accuracy. With the exception of Tc, which is sensitive to contributions from heavy modes, the high-T expansion is found to perform well. 2-loop corrections weaken the transition in IDM, but they are moderate, whereby a strong transition remains an option.

  13. Effect of particle size on the thermal expansion of nanostructured lead sulfide films

    Energy Technology Data Exchange (ETDEWEB)

    Sadovnikov, S.I.; Gusev, A.I., E-mail: gusev@ihim.uran.ru

    2014-10-15

    Highlights: • PbS nanofilms prepared by chemical deposition have a D0{sub 3}-type crystal structure. • Thermal expansion coefficient α of PbS nanofilm is twice as large as that of bulk PbS. • Large difference in the coefficients α is due to the small particle size in PbS film. • Small size of particles in PbS film increases the anharmonicity of atomic vibrations. - Abstract: The effect of particle size on the thermal expansion of nanostructured lead sulfide films produced by hydrochemical deposition has been studied. The coherent scattering region size and thermal expansion coefficients of PbS nanofilm have been measured depending on the annealing temperature in the interval 293–473 K and on the duration of annealing at a constant temperature of 423 K. It is found that the thermal expansion coefficient α of nanostructured PbS film is nearly twice as large as that of bulk lead sulfide. It is shown that the observed large difference in the coefficients α is due to the small size of PbS particles in the film that leads to the change of the phonon spectrum boundaries and to the growth of anharmonicity of atomic vibrations. The additional contribution to the thermal expansion coefficient caused by the small particle size in PbS nanofilm is estimated theoretically.

  14. Effect of occupation on lipid peroxidation and antioxidant status in coal-fired thermal plant workers

    Science.gov (United States)

    Kaur, Sandeep; Gill, Manmeet Singh; Gupta, Kapil; Manchanda, KC

    2013-01-01

    Background: Air pollution from coal-fired power units is large and varied, and contributes to a significant number of negative environmental and health effects. Reactive oxygen species (ROS) have been implicated in the pathogenesis of coal dust-induced toxicity in coal-fired power plants. Aim: The aim of the study was to measure free radical damage and the antioxidant activity in workers exposed to varying levels of coal dust. Material and Methods: The study population consisted of workers in coal handling unit, turbine unit, and boiler unit (n = 50 each), working in thermal power plant; and electricians (n = 50) from same department were taken as controls. Lipid peroxidation was measured by malondialdehyde (MDA) levels and antioxidant activity was determined by superoxide dismutase (SOD) and glutathione peroxidase (GPx) levels. Statistical analysis was carried out by Student's unpaired t-test. Result: MDA levels showed significant increase (P > 0.001) in the thermal power plant workers than the electricians working in the city. The levels of SOD and GPx were significantly higher (P > 0.001) in electricians as compared to subjects working in thermal plant. Among the thermal plant workers, the coal handling unit workers showed significant increase (P > 0.001) in MDA and significant decrease in SOD and GPx than the workers of boiler and turbine unit workers. Conclusion: Oxidative stress due to increase in lipid peroxidation and decrease in antioxidant activity results from exposure to coal dust and coal combustion products during thermal plant activities. PMID:24083143

  15. Effect of Functionalization of Graphene Nanoplatelets on the Mechanical and Thermal Properties of Silicone Rubber Composites

    Directory of Open Access Journals (Sweden)

    Guangwu Zhang

    2016-02-01

    Full Text Available This study investigated the effect of silane and surfactant treatments of graphene nanoplatelets (GnPs on the mechanical and thermal properties of silicone rubber (SR composites. GnPs were modified with aminopropyltriethoxysilane (APTES, vinyltrimethoxysilane (VTMS, and Triton X-100, and then the pristine GnPs and functionalized GnPs were individually incorporated into the SR. Compared with the pristine GnP/SR composite, the composites reinforced with modified GnP showed better tensile strength, elongation at break, and thermal conductivity properties due to better dispersion of modified GnPs and stronger interfacial interactions between the modified GnPs and matrix. The mechanical properties and thermal conductivity of the VTMS-GnP/SR composite were comparable to the properties of the Triton-GnP counterpart, but better than that of the APTES-GnP/SR composite. In addition, the VTMS-GnP/SR composite demonstrated the highest thermal stability and crystallization temperature among the four types of composites. The remarkable improvement of mechanical and thermal properties of the VTMS-GnP/SR composite was mainly due to the covalent linkage of VTMS-GnP with SR. The VTMS treatment was a more appropriate modification of GnP particles to improve the multifunctional properties of SR.

  16. The diversity in thermal behavior of novel catanionic cholates: The dominant effect of quaternary ammonium centers

    Energy Technology Data Exchange (ETDEWEB)

    Mihelj, Tea, E-mail: tmihelj@irb.hr [Department of Physical Chemistry, Ruđer Bošković Institute, POB 180, HR-10002 Zagreb (Croatia); Vojta, Danijela [Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, POB 180, HR-10002 Zagreb (Croatia); Tomašić, Vlasta [Department of Physical Chemistry, Ruđer Bošković Institute, POB 180, HR-10002 Zagreb (Croatia)

    2014-05-01

    Graphical abstract: - Highlights: • Quaternary ammonium cholates characterized as crystal smectics at room temperature. • The domination of quaternary ammonium center seen through diverse thermal behavior. • Thermal changes of cholates keto–enol balance results with prevalence of one form. • Polynomial regression of isotropisation temperatures vs. dodecyl chain number. • Linear descending trend of isotropisation temperatures with higher headgroup number. - Abstract: The thermal behavior of novel catanionic compounds based on cholate anion was examined. The study explains the effect of the raising dodecyl chain number, as well as of the raising headgroup number in quaternary ammonium salts on their physico-chemical properties. The examined samples are crystal smectic phases at room temperature. Their rich and diverse thermal behavior is seen through polymorphic phase transitions, thermotropic mesomorphism of smectic nature and in some cases, kinetically managed crystallization that lasts in days. The changes of the cholates keto–enol isomer balance during thermal treatment are obtained. For both groups of samples temperatures of isotropisation and the thermodynamic parameters follow polynomial regression. Introduction of the new dodecyl chain leads to more ordered structure, while implementation the new headgroup leads to advanced polymer-like structure. The obtained results demonstrate an effort for getting and controlling the regularity of the physico-chemical and thermotropic properties for new compounds by systematic changing of cationic part of the molecule. These informations could provide in the future the easiest way for selection of potentially new and targeted applicable materials.

  17. Effect of nanosilver on thermal and mechanical properties of acrylic base complete dentures.

    Directory of Open Access Journals (Sweden)

    Fahimeh Hamedi-Rad

    2014-10-01

    Full Text Available Polymethyl methacrylate (PMMA, widely used as a prosthodontic base, has many disadvantages, including a high thermal expansion coefficient and low thermal conductivity, a low elasticity coefficient, low impact strength and low resistance to fatigue. This study aimed to make an in vitro comparison of the thermal conductivity, compressive strength, and tensile strength of the acrylic base of complete dentures with those of acrylic reinforced with nanosilver.For this study, 36 specimens were prepared. The specimens were divided into three groups of 12; which were further divided into two subgroups of control (unmodified PMMA and test (PMMA mixed with 5 weight% nanosilver.The results were analysed by Independent t-test.This study showed that the mean thermal conductivity and compressive strength of PMMA reinforced with nanosilver were significantly higher than the unmodified PMMA (P<0.05, while the tensile strength decreased significantly after the incorporation of nanosilver (P<0.05.Considering our results suggesting the favorable effect of silver nanoparticles on improving the thermal conductivity and compressive strength of PMMA, use of this material in the palatal area of maxillary acrylic resin dentures is recommended.

  18. Thermal effects induced by laser ablation in non-homogeneous limestone covered by an impurity layer

    Science.gov (United States)

    Cocean, Alexandru; Pelin, Vasile; Cazacu, Marius Mihai; Cocean, Iuliana; Sandu, Ion; Gurlui, Silviu; Iacomi, Felicia

    2017-12-01

    This paper reports preliminary results concerning thermal effects induced by urban/industrial air pollutants deposited on a limestone rock when heated by pulsed laser in the cleaning process. The process of laser cleaning treatment of the crust is simulated using COMSOL Multiphysics 4.4, finite element analysis software. Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy and Laser Induced Breakdown Spectroscopy techniques have been used to analyze the chemical composition of the samples. Two elements found as being present into the dust and in the crust, such as iron and magnesium particles are used for simulation in COMSOL. Therefore, the profiles heat evolutions on the crust surface and inside limestone are obtained as thermal interactions between the three components (iron, magnesium and limestone), simulating the non-homogeneous materials. It has been observed that iron impurities caused by the dust deposition may damage the limestone through a process of overheating, as a consequence of a high thermal conduction phenomenon, recorded for the region with iron impurities and sizes of micrometric order are localized. The thermal contact between the three components results in plots that reflect their thermal interactions.

  19. Effect of thermal cycling and disinfection on colour stability of denture base acrylic resin.

    Science.gov (United States)

    Goiato, Marcelo C; Dos Santos, Daniela M; Baptista, Gabriella T; Moreno, Amália; Andreotti, Agda M; Bannwart, Lisiane C; Dekon, Stefan F C

    2013-12-01

    The purpose of this study was to investigate the effect of thermal cycling and disinfection on the colour change of denture base acrylic resin. Four different brands of acrylic resins were evaluated (Onda Cryl, QC 20, Classico and Lucitone). All brands were divided into four groups (n = 7) determined according to the disinfection procedure (microwave, Efferdent, 4% chlorhexidine or 1% hypochlorite). The treatments were conducted three times a week for 60 days. All specimens were thermal cycled between 5 and 55°C with 30-s dwell times for 1000 cycles before and after disinfection. The specimens' colour was measured with a spectrophotometer using the CIE L*a*b* system. The evaluations were conducted at baseline (B), after first thermal cycling (T1 ), after disinfection (D) and after second thermal cycling (T2 ). Colour differences (ΔE) were calculated between T1 and B (T1 B), D and B (DB), and T2 and B (T2 B) time-points.   The samples submitted to disinfection by microwave and Efferdent exhibited the highest values of colour change. There were significant differences on colour change between the time-points, except for the Lucitone acrylic resin. The thermal cycling and disinfection procedures significantly affected the colour stability of the samples. However, all values obtained for the acrylic resins are within acceptable clinical parameters. © 2012 John Wiley & Sons A/S and The Gerodontology Society. Published by John Wiley & Sons Ltd.

  20. Effect of thermal cycling and disinfection on microhardness of acrylic resin denture base.

    Science.gov (United States)

    Goiato, Marcelo Coelho; Dos Santos, Daniela Micheline; Baptista, Gabriella Trunckle; Moreno, Amália; Andreotti, Agda Marobo; Dekon, Stéfan Fiuza de Carvalho

    2013-04-01

    The purpose of this study was to investigate the effect of thermal cycling and disinfection on the microhardness of acrylic resins denture base. Four different brands of acrylic resins were evaluated: Onda Cryl, QC 20, Classico and Lucitone. Each brand of acrylic resin was divided into four groups (n = 7) according to the disinfection method (microwave, Efferdent, 4% chlorhexidine and 1% hypochlorite). Samples were disinfected during 60 days. Before and after disinfection, samples were thermal cycled between 5-55 °C with 30-s dwell times for 1000 cycles. The microhardness was measured using a microhardener, at baseline (B), after first thermal cycling (T1), after disinfection (D) and after second thermal cycling (T2). The microhardness values of all groups reduced over time. QC-20 acrylic resin exhibited the lowest microhardness values. At B and T1 periods, the acrylic resins exhibited statistically greater microhardness values when compared to D and T2 periods. It can be concluded that the microhardness values of the acrylic resins denture base were affected by the thermal cycling and disinfection procedures. However, all microhardness values obtained herein are within acceptable clinical limits for the acrylic resins.

  1. Effects of thermal hydrolysis temperature on physical characteristics of municipal sludge.

    Science.gov (United States)

    Feng, Guohong; Guo, Yabing; Tan, Wei

    2015-01-01

    Effects of thermal hydrolysis temperature on the physical properties of municipal sludge was further studied by a series of experiments. There was a decrease in bound water content with an increase in hydrolysis temperature, while there was an increase in pH at temperatures below 120 °C, and a decrease at temperatures exceeding 120 °C. An analysis of settleability, centrifugation and vacuum filtration of the treated sludge indicated that the threshold temperature was 120 °C, which was the same as the temperature for the bound water content and particle size. In addition, raw sludge with a solids content of 100 g/L, exhibited significant non-Newtonian fluid characteristics. At thermal hydrolysis temperatures exceeding 120 °C, non-Newtonian fluid characteristics including liquid and solid characteristics were significantly weakened. The consistency index (k) decreased from 5.90 Pa·s to 0.068 Pa·s, while the flow index (n) increased from 0.31 to 0.74, suggesting that thermal hydrolysis sludge was much closer to Newtonian fluids compared to raw sludge. Modification of bound water content, particle size and viscosity with hydrolysis temperature, revealed the nature of improved dewaterability by thermal hydrolysis. The fractal dimension of the sludge floc increased from 2.74 to 2.90, meaning that the floc became more compact after thermal hydrolysis.

  2. Microwave thermal ablation: Effects of tissue properties variations on predictive models for treatment planning.

    Science.gov (United States)

    Lopresto, Vanni; Pinto, Rosanna; Farina, Laura; Cavagnaro, Marta

    2017-08-01

    Microwave thermal ablation (MTA) therapy for cancer treatments relies on the absorption of electromagnetic energy at microwave frequencies to induce a very high and localized temperature increase, which causes an irreversible thermal damage in the target zone. Treatment planning in MTA is based on experimental observations of ablation zones in ex vivo tissue, while predicting the treatment outcomes could be greatly improved by reliable numerical models. In this work, a fully dynamical simulation model is exploited to look at effects of temperature-dependent variations in the dielectric and thermal properties of the targeted tissue on the prediction of the temperature increase and the extension of the thermally coagulated zone. In particular, the influence of measurement uncertainty of tissue parameters on the numerical results is investigated. Numerical data were compared with data from MTA experiments performed on ex vivo bovine liver tissue at 2.45GHz, with a power of 60W applied for 10min. By including in the simulation model an uncertainty budget (CI=95%) of ±25% in the properties of the tissue due to inaccuracy of measurements, numerical results were achieved in the range of experimental data. Obtained results also showed that the specific heat especially influences the extension of the thermally coagulated zone, with an increase of 27% in length and 7% in diameter when a variation of -25% is considered with respect to the value of the reference simulation model. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  3. Effects of thermal treatment on colour and texture of Typha latifolia L.

    Science.gov (United States)

    Zhang, Min; Zhou, Yun-hua; Wang, Shaojin; Tang, Juming

    2012-04-01

    Through the analysis of the residual activity of peroxidase (POD), chromatic aberration, shear intensity and shear power, the effects of different thermal treatment times at 100°C on the POD, surface colour and texture of Typha latifolia L. were evaluated. The results showed that the activity of POD decreased with the increasing thermal treatment time at 100°C. The regeneration amount of POD increased first for some time and then started to decrease with the treatment time. Thermal treatment times 1.0 and 1.5 min at 100°C exhibited maximum regeneration of POD for the samples stored at 20 and 37°C, respectively. The sample had acceptable texture and surface colour when they were treated at 100°C for 4 min because the POD in the sample was inactivated to an acceptable level.

  4. Development of process equipment to separate nonthermal and thermal effects of RF energy on microorganisms.

    Science.gov (United States)

    Brunkhorst, C; Ciotti, D; Fredd, E; Wilson, J R; Geveke, D J; Kozempel, M

    2000-01-01

    We developed a modified radio frequency (RF) dielectric heater, as a component of a continuous process, for isolating thermal and nonthermal effects of RF energy on microorganisms in liquid foods. The concept combines instantaneous input of RF energy to the food system with rapid removal of thermal energy. We used a double tube heat exchanger as an integral part of the RF heater. The outer tube was Teflon. The inner tube was stainless steel which was grounded in the RF circuit. Product flowed through the annular region between the two concentric tubes. Cooling water flowed through the grounded stainless steel tube. The RF energy was absorbed by the process fluid in the annular region. The cooling water flowing in the inner tube removed the thermal energy from the process fluid controlling the temperature.

  5. Effects of Silver Microparticles and Nanoparticles on Thermal and Electrical Characteristics of Electrically Conductive Adhesives

    Science.gov (United States)

    Zulkarnain, M.; Fadzil, M. A.; Mariatti, M.; Azid, I. A.

    2017-11-01

    The effects of different volume fractions of silver (Ag) particles of different size (microsize, 2 μm to 3.5 μm diameter; nanosize, 80 nm diameter) on the thermal and electrical characteristics of epoxy-Ag electrically conductive adhesive (ECA) have been evaluated, as well as hybrid ECAs with both particle sizes at different ratios. Improved thermal and electrical conductivity resulted from the interaction between the particles, as evaluated by analysis of sample morphology. The interaction was altered to improve the conductivity. For both particle sizes, the electrical resistivity showed a transition from insulation to conduction at 6 vol.% Ag. In the hybrid system, the thermal conductivity decreased with increasing microparticle filler ratio. The electrical conductivity of the hybrid composite increased at 50:50 weight ratio.

  6. Effect of Rotor Diameter on the Thermal Stresses of a Turbine Rotor Model

    Science.gov (United States)

    Dávalos, J. O.; García, J. C.; Urquiza, G.; Castro-Gómez, L. L.; Rodríguez, J. A.; De Santiago, O.

    2016-04-01

    Thermal stresses in a simplified steam turbine rotor model during a cold startup are analyzed using finite element analysis (FEA). In order to validate the numerical model, an experimental array is developed in which a hollow cylinder is heated with hot air in the external surface. At the thick wall of the cylinder, temperature distribution is measured in real time, while at the same time an algorithm computes thermal stresses. Additional computational fluid dynamics (CFD) calculations are made to obtain magnitudes of velocity and pressure in order to compute convective heat transfer coefficient. The experimental results show good agreement with the FEA computations. To evaluate the effect of rotor diameter size, FEA computations with variation in external and internal diameters are performed. Results show that thermal stresses are proportional to rotor diameter size. Also, zones of higher stress concentration are found in the external and internal surfaces of the rotor.

  7. Thermal effects of variable material properties and metamorphic reactions in a three-component subducting slab

    DEFF Research Database (Denmark)

    Chemia, Zurab; Dolejš, David; Steinle-Neumann, Gerd

    2015-01-01

    We explore the effects of variable material properties, phase transformations, and metamorphic devolatilization reactions on the thermal structure of a subducting slab using thermodynamic phase equilibrium calculations combined with a thermal evolution model. The subducting slab is divided...... within the slab is limited. Two extreme scenarios are considered for a newly forming fluid phase: complete retention in the rock pore space or instantaneous fluid escape due to porosity collapse. Internal heat generation or consumption due to variable heat capacity, compressional work, and energetics...... of progressive metamorphic and devolatilization reactions contribute to the thermal evolution of the slab in addition to the dominating heat flux from the surrounding mantle. They can be considered as a perturbation on the temperature profile obtained in dynamic or kinematic subduction models. Our calculations...

  8. Seismology of adolescent neutron stars: Accounting for thermal effects and crust elasticity

    CERN Document Server

    Krüger, C J; Andersson, N

    2014-01-01

    We study the oscillations of relativistic stars, incorporating key physics associated with internal composition, thermal gradients and crust elasticity. Our aim is to develop a formalism which is able to account for the state-of-the-art understanding of the complex physics associated with these systems. As a first step, we build models using a modern equation of state including composition gradients and density discontinuities associated with internal phase-transitions (like the crust-core transition and the point where muons first appear in the core). In order to understand the nature of the oscillation spectrum, we carry out cooling simulations to provide realistic snapshots of the temperature distribution in the interior as the star evolves through adolescence. The associated thermal pressure is incorporated in the perturbation analysis, and we discuss the presence of $g$-modes arising as a result of thermal effects. We also consider interface modes due to phase-transitions and the gradual formation of the...

  9. Effects of polymer additives in the bulk of turbulent thermal convection

    CERN Document Server

    Xie, Yi-Chao; Funfschilling, Denis; Li, Xiao-Ming; Ni, Rui; Xia, Ke-Qing

    2015-01-01

    We present experimental evidence that a minute amount of polymer additives can significantly enhance heat transport in the bulk region of turbulent thermal convection. The effects of polymer additives are found to be the \\textit{suppression} of turbulent background fluctuations that give rise to incoherent heat fluxes that make no net contribution to heat transport, and at the same time to \\textit{increase} the coherency of temperature and velocity fields. The suppression of small-scale turbulent fluctuations leads to more coherent thermal plumes that result in the heat transport enhancement. The fact that polymer additives can increase the coherency of thermal plumes is supported by the measurements of a number of local quantities, such as the extracted plume amplitude and width, the velocity autocorrelation functions and the velocity-temperature cross-correlation coefficient. The results from local measurements also suggest the existence of a threshold value for the polymer concentration, only above which c...

  10. Predicting effects of cold shock: modeling the decline of a thermal plume

    Energy Technology Data Exchange (ETDEWEB)

    Becker, C.D.; Trent, D.S.; Schneider, M.J.

    1977-10-01

    Predicting direct impact of cold shock on aquatic organisms after termination of power plant thermal discharges requires thermal tests that provide quantitative data on the resistance of acclimated species to lower temperatures. Selected examples from the literature on cold shock resistance of freshwater and marine fishes are illustrated to show predictive use. Abrupt cold shock data may be applied to field situations involving either abrupt or gradual temperature declines but yield conservative estimates under the latter conditions. Gradual cold shock data may be applied where heated plumes gradually dissipate because poikilotherms partially compensate for lowering temperature regimes. A simplified analytical model is presented for estimating thermal declines in terminated plumes originating from offshore, submerged discharges where shear current and boundary effects are minimal. When applied to site-specific conditions, the method provides time-temperature distributions for correlation with cold resistance data and, therefore, aids in assessing cold shock impact on aquatic biota.

  11. Thermal plume effects: A multi-disciplinary approach for assessing effects of thermal pollution on estuaries using benthic diatoms and satellite imagery

    Science.gov (United States)

    Ingleton, Timothy; McMinn, Andrew

    2012-03-01

    Rapid, reliable and cost-effective techniques for assessing and monitoring pollution are required because of increased development pressures associated with continued population growth. An innovative multi-disciplinary approach was applied to a power station discharge in Lake Macquarie, Australia, using benthic diatoms, water quality, satellite imagery and temperature loggers. Triplicate sediment samples at five sites across a thermal gradient in one plume affected and two control bays were analysed for benthic diatoms. Multivariate analysis indicated that diatom assemblages and environmental gradients in the receiving water embayment were significantly different to control bays. The plume affected benthic assemblages to greater depths (˜4.7 m) than observed by previous studies and this is likely to have implications for estimates of estuarine productivity and nutrient cycling. Of the 244 diatom taxa identified, Navicula rhaphoneis appeared to best identify areas of the lake bed exposed to temperatures 3-4 °C above ambient (ΔT). Tryblionella lanceola, Tryblionella littoralis, Grammatophora spp. and Psammodictyon panduriformis also contributed to gradients and might be used as plume indicator species. Temperature, ammonia, oxidised nitrogen and selenium significantly explained gradients in the species data (p = 0.02). Satellite imagery indicated that receiving bay temperature gradients (<7 °C) were greatest in winter, whereas loggers showed ΔT was greatest in autumn then winter. These analyses highlighted that seasonality is an important factor when considering the effects of thermal plumes on receiving environment ecology. Analyses of imagery and logger data are effective techniques for managers to routinely assess plume intensity and extent. This study demonstrates that both benthic diatoms and satellite imagery are valuable tools for the monitoring and assessment of thermal pollution in coastal environments.

  12. Optical monitoring of thermal effects in RPE during heating

    Science.gov (United States)

    Schuele, G.; Huie, Ph.; Yellachich, D.; Molnar, F. E.; O'Conell-Rodwell, C.; Vitkin, E.; Perelman, L. T.; Palanker, D.

    2005-04-01

    Fast and non-invasive detection of cellular stress is useful for fundamental research and practical applications in medicine and biology. Using Light Scattering Spectroscopy we extract information about changes in refractive index and size of the cellular organelles. Particle sizes down to 50nm in diameter can be detected using light within the spectral range of 450-850 nm. We monitor the heat-induced sub-cellular structural changes in human RPE cells and, for comparison, in transfected NIH-3T3 cells which express luciferase linked to the heat shock protein (HSP). Using inverse light scattering fitting algorithm, we reconstruct the size distribution of the sub-micron organelles from the light scattering spectrum. The most significant (up to 70%) and rapid (20sec) temperature-related changes can be linked to an increase of refractive index of the 160nm sized mitochondria. The start of this effect coincides with the onset of HSP expression. This technique provides an insight into metabolic processes within organelles larger than 50nm without exogenous staining and opens doors for non-invasive real-time assessment of cellular stress, which can be used for monitoring of retinal laser treatments like transpupillary thermo therapy or PDT.

  13. Thermal effects on arsenic emissions during coal combustion process.

    Science.gov (United States)

    Zhang, Weiqiang; Sun, Qiang; Yang, Xiuyuan

    2018-01-15

    In this study, the rate of emission of arsenic during the burning process of different kinds of coal is examined in order to study the volatile characteristics of arsenic during coal combustion which have negative effects on the ecological environment and human health. The results show that the emission rate of arsenic gradually increases with increased burning temperature, with a threshold of approximately 700°C to 800°C in the process of temperature increase. Then, the relationships among the arsenic emission rate and combustion environment, original arsenic content, combustion time, burning temperature, air flow and amount of arsenic fixing agent are discussed, and it is found that except for the original arsenic content, the rest of the factors have a nonlinear relationship with the emission rate of arsenic. That is, up to a certain level, they all contribute to the release of arsenic, and then their impact is minimal. The original arsenic content in coal is proportional to the arsenic emission rate. Therefore, taking into consideration the nonlinear relationships between factors that affect the arsenic emission rate can reduce contamination from arsenic. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Effect of thermal acclimation on thermal preference, resistance and locomotor performance of hatchling soft-shelled turtle

    Directory of Open Access Journals (Sweden)

    Mei-Xian WU,Ling-Jun HU, Wei DANG, Hong-Liang LU, Wei-Guo DU

    2013-12-01

    Full Text Available The significant influence of thermal acclimation on physiological and behavioral performance has been documented in many ectothermic animals, but such studies are still limited in turtle species. We acclimated hatchling soft-shelled turtles Pelodiscus sinensis under three thermal conditions (10, 20 and 30 °C for 4 weeks, and then measured selected body temperature (Tsel, critical thermal minimum (CTMin and maximum (CTMax, and locomotor performance at different body temperatures. Thermal acclimation significantly affected thermal preference and resistance of P. sinensis hatchlings. Hatchling turtles acclimated to 10 °C selected relatively lower body temperatures and were less resistant to high temperatures than those acclimated to 20 °C and 30 °C. The turtles’ resistance to low temperatures increased with a decreasing acclimation temperature. The thermal resistance range (i.e. the difference between CTMax and CTMin, TRR was widest in turtles acclimated to 20 °C, and narrowest in those acclimated to 10 °C. The locomotor performance of turtles was affected by both body temperature and acclimation temperature. Hatchling turtles acclimated to relatively higher temperatures swam faster than did those acclimated to lower temperatures. Accordingly, hatchling turtles acclimated to a particular temperature may not enhance the performance at that temperature. Instead, hatchlings acclimated to relatively warm temperatures have a better performance, supporting the “hotter is better” hypothesis [Current Zoology 59 (6 : 718–724, 2013 ].

  15. The effectiveness of the newly designed thermal gown on hypothermic patients after spinal surgery.

    Science.gov (United States)

    Lee, Wen-Ping; Wu, Pao-Yuan; Shih, Whei-Mei; Lee, Meng-Ying; Ho, Lun-Hui

    2015-10-01

    To develop the newly designed thermal gown to test the effectiveness in relieving postoperative hypothermia as compared to traditional cotton cloth. Hypothermia is a common problem after spinal surgery. A patient's safety and comfort are significant. Currently, most research is focused on instruments that relieve a patient's hypothermia. Studies have rarely considered a patient's comfort while caring for their body temperature. This study employed an experimental design. The participants were assigned randomly to two groups: the experimental group (N = 50) and the control group (N = 50). The experimental group received the newly designed thermal gown intervention. The control group received the standard postanaesthesia care unit re-warming intervention. The material used to collect data included demographic data, postoperative management and comfort level. Nurses measured patients' vital signs and asked for patients' subjective comfort level on admission to the postanaesthesia care unit every 10 minutes until their discharge from the postanaesthesia care unit. The accumulated percentage for thermal gown group patients in reaching 36 °C during the first 20 minutes of admission was significantly higher than that of the cotton cloth group. The thermal gown group individuals showed significantly higher comfort levels (score = 4) at 10 minutes, when compared to the cotton cloth group. Results suggested that the newly designed thermal gown had effectively improved postoperative temperature and comfort level with an evidence-based intervention. Maintaining a patient's body temperature is a major task for nurses working in the post-anaesthesia care unit. With the newly designed thermal gown, the duration of a patient's stay in the postanaesthesia care unit was shortened and the patient's comfort was increased. © 2015 John Wiley & Sons Ltd.

  16. Effect of Thermal Processing on the Nutritional, Antinutritional, and Antioxidant Properties of Tetracarpidium conophorum (African Walnut

    Directory of Open Access Journals (Sweden)

    S. Olanrewaju Arinola

    2014-01-01

    Full Text Available The effect of thermal processing (roasting and boiling on the nutritional, antinutritional, and antioxidant properties of African walnut was studied. Tetracarpidium conophorum (African walnut was subjected to thermal treatment of roasting (RWIS, boiling with shell (BWIS, and boiling without shell (BWOS. The resulting samples with raw nut (RAAW which served as control were analysed for proximate composition, antinutritional components, and antioxidant activity. The protein, fat, and ash contents of the samples on dry basis were 29.14%, 54.14%, and 3.32% (RAAW; 24.13%, 61.75%, and 2.77% (BWIS; 22.47%, 62.65%, and 2.16% (BWOS; and 24.25%, 60.52%, and 2.48% (RWIS, respectively. Thermal processing had significant effect on all the proximate principles; boiling and roasting generally reduced the protein and ash contents of the nut. Boiling with or without shell reduced the phytate and tannin contents of the nut while roasting increased the level of these two antinutritional components; walnut boiled without shell however, had the lowest phytate and tannin contents of 0.815 mg/100 g and 0.239 mg/100 g, respectively. The antioxidant activities of the samples were 8.47% (RAAW, 13.82% (BWIS, 14.96% (BWOS, and 7.29% (RWIS. This study reveals that thermal processing has a significant effect on the proximate principles, bioavailability, and antioxidant activity of African walnut.

  17. The effect of reinforcement volume ratio on porosity and thermal conductivity in Al-Mgo composites

    Directory of Open Access Journals (Sweden)

    Recep Calin

    2012-12-01

    Full Text Available In this study, the effects of reinforcement volume ratios (RVR on composite structure and thermal conductivity were examined in Al-MgO reinforced metal matrix composites (MMCs of 5%, 10% and 15% RVR produced by melt stirring. In the production of composites, EN AW 1050A aluminum alloy was used as the matrix material and MgO powders with particle size of -105 µm were used as the reinforcement material. For every composite specimen was produced at 500 rev/min stirring speed, at 750 °C liquid matrix temperature and 4 minutes stirring time. Composite samples were cooled under normal atmosphere. Then, microstructures of the samples were determined and evaluated by using Scanning Electron Microscope (SEM and Energy Dispersive X-ray Spectroscopy (EDS analysis. In general, it was observed that the reinforcement exhibited a homogeneous distribution. Furthermore, it was determined that the increase in the RVR increased porosity. From the Scanning Electron Microscope images, a thermal Ansys model was generated to determine effective thermal conductivity. Effective thermal conductivity of Al-MgO composites increased with the decrease in reinforcement volume ratio.

  18. Effective thermal conductivity and diffusivity of containment wall for nuclear power plant OPR1000

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Hyung Gyun; Park, Hyun Sun [Div. of Advanced Nuclear Engineering (DANE), Pohang University of Science and Technology (POSTECH), Pohang (Korea, Republic of); Lee, Jong Hwi; Kang, Hie Chan [Mechanical Engineering Div., Kunsan National University (KNU), Gunsan (Korea, Republic of)

    2017-04-15

    The goal of this study is to evaluate the effective thermal conductivity and diffusivity of containment walls as heat sinks or passive cooling systems during nuclear power plant (NPP) accidents. Containment walls consist of steel reinforced concrete, steel liners, and tendons, and provide the main thermal resistance of the heat sinks, which varies with the volume fraction and geometric alignment of the rebar and tendons, as well as the temperature and chemical composition. The target geometry for the containment walls of this work is the standard Korean NPP OPR1000. Sample tests and numerical simulations are conducted to verify the correlations for models with different densities of concrete, volume fractions, and alignments of steel. Estimation of the effective thermal conductivity and diffusivity of the containment wall models is proposed. The Maxwell model and modified Rayleigh volume fraction model employed in the present work predict the experiment and finite volume method (FVM) results well. The effective thermal conductivity and diffusivity of the containment walls are summarized as functions of density, temperature, and the volume fraction of steel for the analysis of the NPP accidents.

  19. Effects of morphine on thermal sensitivity in adult and aged rats.

    Science.gov (United States)

    Morgan, Drake; Mitzelfelt, Jeremiah D; Koerper, Lorraine M; Carter, Christy S

    2012-06-01

    There are contradictory data regarding older individuals' sensitivity to pain stimulation and opioid administration. Adult (12-16 months; n = 10) and aged (27-31 months; n = 7) male F344xBN rats were tested in a thermal sensitivity procedure where the animal chooses to remain in one of two compartments with floors maintained at various temperatures ranging from hot (45°C) through neutral (30°C) to cold (15°C). Effects of morphine were determined for three temperature comparisons (ie, hot/neutral, cold/neutral, and hot/cold). Aged rats were more sensitive to cold stimulation during baseline. Morphine produced antinociception during hot thermal stimulation, but had no effect on cold stimulation. The antinociceptive (and locomotor-altering) effects of morphine were attenuated in aged rats. These data demonstrate age-related differences in baseline thermal sensitivity and responsiveness to opioids. Based on behavioral and physiological requirements of this procedure, it is suggested that thermal sensitivity may provide a relevant animal model for the assessment of pain and antinociception.

  20. Effect of anisotropic thermal transport on the resistive plasma response to resonant magnetic perturbation field

    Science.gov (United States)

    Bai, Xue; Liu, Yueqiang; Gao, Zhe

    2017-10-01

    Plasma response to the resonant magnetic perturbation (RMP) field is numerically investigated by an extended toroidal fluid model, which includes anisotropic thermal transport physics parallel and perpendicular to the total magnetic field. The thermal transport is found to be effective in eliminating the toroidal average curvature induced plasma screening (the so called Glasser-Green-Johnson, GGJ screening) in a slow toroidal flow regime, whilst having minor effect on modifying the conventional plasma screening regimes at faster flow. This physics effect of interaction between thermal transport and GGJ screening is attributed to the modification of the radial structure of the shielding current, which resulted from the plasma response to the applied field. The modification of the plasma response (shielding current, response field, plasma displacement, and the perturbed velocity) also has direct consequence on the toroidal torques produced by RMP. Modelling results show that thermal transport reduces the resonant electromagnetic torque as well as the torque associated with the Reynolds stress, but enhances the neoclassical toroidal viscous torque at slow plasma flow.

  1. Probing whole cell currents in high-frequency electrical fields: identification of thermal effects.

    Science.gov (United States)

    Olapinski, Michael; Manus, Stephan; Fertig, Niels; Simmel, Friedrich C

    2008-01-18

    An open-end coaxial probe is combined with a planar patch-clamp system to apply electric fields with GHz frequencies during conventional patch-clamp measurements. The combination of pulsed microwave irradiation and lock-in detection allows for the separation of fast and slow effects and hence facilitates the identification of thermal effects. The setup and the influence of radiation on the patch-clamp current are thoroughly characterized. For the independent optical verification of heating effects, a temperature microscopy technique is applied with high spatial, temporal and temperature resolution. It is shown that the effect of radiation at GHz frequencies on whole cell currents is predominantly thermal in nature in the case of RBL cells with an endogenous K(ir) 2.1 channel.

  2. Heats of Mixing Using an Isothermal Titration Calorimeter: Associated Thermal Effects

    Directory of Open Access Journals (Sweden)

    Fabiola Socorro

    2009-06-01

    Full Text Available The correct determination of the energy generated or absorbed in the sample cell of an Isothermal Titration Calorimeter (ITC requires a thorough analysis of the calorimetric signal. This means the identification and quantification of any thermal effect inherent to the working method. In this work, it is carried out a review on several thermal effects, studied by us in previous work, and which appear when an ITC is used for measuring the heats of mixing of liquids in a continuous mode. These effects are due to: (i the difference between the temperature of the injected liquid and the temperature of the mixture during the mixing process, (ii the increase of the liquid volume located in the mixing cell and (iii the stirring velocity. Besides, methods for the identification and quantification of the mentioned effects are suggested.

  3. Clothing resultant thermal insulation determined on a movable thermal manikin. Part I: effects of wind and body movement on total insulation.

    Science.gov (United States)

    Lu, Yehu; Wang, Faming; Wan, Xianfu; Song, Guowen; Shi, Wen; Zhang, Chengjiao

    2015-10-01

    In this serial study, 486 thermal manikin tests were carried out to examine the effects of air velocity and walking speed on both total and local clothing thermal insulations. Seventeen clothing ensembles with different layers (i.e., one, two, or three layers) were selected for the study. Three different wind speeds (0.15, 1.55, 4.0 m/s) and three levels of walking speed (0, 0.75, 1.2 m/s) were chosen. Thus, there are totally nine different testing conditions. The clothing total insulation and local clothing insulation at different body parts under those nine conditions were determined. In part I, empirical equations for estimating total resultant clothing insulation as a function of the static thermal insulation, relative air velocity, and walking speed were developed. In part II, the local thermal insulation of various garments was analyzed and correction equations on local resultant insulation for each body part were developed. This study provides critical database for potential applications in thermal comfort study, modeling of human thermal strain, and functional clothing design and engineering.

  4. Effects of thermal budget in n-type bifacial solar cell fabrication processes on effective lifetime of crystalline silicon

    Directory of Open Access Journals (Sweden)

    Tomihisa Tachibana

    2017-04-01

    Full Text Available The effects of residual C on cell properties are investigated from the view point of thermal budget in the n-type bifacial cell processes. Implied Voc obtained from wafers with same Oi concentration depend on the thermal budgets decreases as the Cs concentration increases. The Voc values vary depending on the wafer with different growth cooling rate. To analyze the effect of thermal budget correspond to solar cell fabrication process, CZ wafers with almost the same Oi concentrations are prepared. One of the wafers with relatively high residual Cs concentration shows the longer lifetime than the initial value after the 950 oC annealing step. On the other hand, the lifetime of a wafer with relatively low Cs concentration dramatically decreased by the same process due to the O segregation. These results suggest that it is important to choose appropriate wafer specification, starting with feedstock material, for increasing the solar cell efficiency.

  5. Effect of three-spin interaction on thermal entanglement in Heisenberg XXZ model

    Science.gov (United States)

    Fu, Jing-Heng; Zhang, Guo-Feng

    2017-11-01

    The effect of three-spin interaction k on thermal entanglement between alternate qubits is studied using pairwise concurrence C and energy-level diagram. It is found that k breaks the symmetry about the effect of magnetic field h on C. It shifts a dip structure and gradually effaces a boot structure when | k | | J | . A sudden change in the concurrence occurs around | k | =| J | , h=-k. Similar conclusions about nearest-neighbor qubits are directly given.

  6. Studying bio-thermal effects at and around MSW dumps using Satellite Remote Sensing and GIS.

    Science.gov (United States)

    Mahmood, Khalid; Batool, Syeda Adila; Chaudhry, Muhammad Nawaz

    2016-09-01

    Estimating negative impacts of MSW dumps on its surrounding environment is the key requirement for any remedial measures. This study has been undertaken to map bio-thermal effects of MSW dumping at and around dumping facilities (non-engineered) using satellite imagery for Faisalabad, Pakistan. Thirty images of Landsat 8 have been selected after validation for the accuracy of their observational details from April 2013 to October 2015. Land Surface Temperature (LST), NDVI, SAVI and MSAVI have been derived from these images through Digital Image Processing (DIP) and have been subjected to spatio-temporal analysis in GIS environment. MSW dump has been found with average temperature elevation of 4.3K and 2.78K from nearby agriculture land and urban settlement respectively. Vegetation health has been used as the bio-indicator of MSW effects and is implemented through NDVI, SAVI, MSAVI. Spatial analyses have been used to mark boundary of bio-thermally affected zone around dumped MSW and measure 700m. Seasonal fluctuations of elevated temperatures and boundary of the bio-thermally affected zones have also been discussed. Based on the direct relation found between vegetation vigor and the level of deterioration within the bio-thermally affected region, use of crops with heavy vigor is recommended to study MSW hazard influence using bio-indicators of vegetation health. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Thermal characterization of a new effective building material based on clay and olive waste

    Directory of Open Access Journals (Sweden)

    Mohamed Lamrani

    2018-01-01

    Full Text Available The influence of thermophysical properties of wall materials on energy performance and comfort in traditional building was investigated. The clay is the most commonly used sustainable building material. The study looked at the effects of the addition of pomace olive on the thermophysical properties of clay bricks to improve the energy efficiency of this ecological material. An experimental measurement of thermal properties of clay mixed with pomace olive was carried out by using the transient and steady state hot-plate and flash methods. The experimental methods are applied to measure the thermal properties of the composite material. The estimation of these thermal characteristics is based on a one dimensional model and the experimental errors are found less than 3%. The composite samples were prepared with different granular classes and mass fractions of the pomace olive in the mixture. The results show that the density of the new material was not substantially influenced by the size of the pomace olive. However, the thermal conductivity and diffusivity decrease from 0.65 W.m-1.K-1 and 4.21×10-7 m2.s-1 to 0.29 W.m-1.K-1 and 2.47×10-7m2.s-1, respectively, according to the variation of the volume fraction of pomace olive from 0 (pure clay to 71% showing that the olive pomace can be used as effective secondary raw materials in the making of clay bricks.

  8. Effects of Urban Configuration on Human Thermal Conditions in a Typical Tropical African Coastal City

    Directory of Open Access Journals (Sweden)

    Emmanuel Lubango Ndetto

    2013-01-01

    Full Text Available A long-term simulation of urban climate was done using the easily available long-term meteorological data from a nearby synoptic station in a tropical coastal city of Dar es Salaam, Tanzania. The study aimed at determining the effects of buildings’ height and street orientations on human thermal conditions at pedestrian level. The urban configuration was represented by a typical urban street and a small urban park near the seaside. The simulations were conducted in the microscale applied climate model of RayMan, and results were interpreted in terms of the thermal comfort parameters of mean radiant (Tmrt and physiologically equivalent (PET temperatures. PET values, high as 34°C, are observed to prevail during the afternoons especially in the east-west oriented streets, and buildings’ height of 5 m has less effect on the thermal comfort. The optimal reduction of Tmrt and PET values for pedestrians was observed on the nearly north-south reoriented streets and with increased buildings’ height especially close to 100 m. Likewise, buildings close to the park enhance comfort conditions in the park through additional shadow. The study provides design implications and management of open spaces like urban parks in cities for the sake of improving thermal comfort conditions for pedestrians.

  9. Effects of flow and colony morphology on the thermal boundary layer of corals

    Science.gov (United States)

    Jimenez, Isabel M.; Kühl, Michael; Larkum, Anthony W. D.; Ralph, Peter J.

    2011-01-01

    The thermal microenvironment of corals and the thermal effects of changing flow and radiation are critical to understanding heat-induced coral bleaching, a stress response resulting from the destruction of the symbiosis between corals and their photosynthetic microalgae. Temperature microsensor measurements at the surface of illuminated stony corals with uneven surface topography (Leptastrea purpurea and Platygyra sinensis) revealed millimetre-scale variations in surface temperature and thermal boundary layer (TBL) that may help understand the patchy nature of coral bleaching within single colonies. The effect of water flow on the thermal microenvironment was investigated in hemispherical and branching corals (Porites lobata and Stylophora pistillata, respectively) in a flow chamber experiment. For both coral types, the thickness of the TBL decreased exponentially from 2.5 mm at quasi-stagnant flow (0.3 cm s−1), to 1 mm at 5 cm s−1, with an exponent approximately 0.5 consistent with predictions from the heat transfer theory for simple geometrical objects and typical of laminar boundary layer processes. Measurements of mass transfer across the diffusive boundary layer using O2 microelectrodes revealed a greater exponent for mass transfer when compared with heat transfer, indicating that heat and mass transfer at the surface of corals are not exactly analogous processes. PMID:21602322

  10. Effect of non-homogenous thermal stress during sub-lethal photodynamic antimicrobial chemotherapy

    Science.gov (United States)

    Gadura, N.; Kokkinos, D.; Dehipawala, S.; Cheung, E.; Sullivan, R.; Subramaniam, R.; Schneider, P.; Tremberger, G., Jr.; Holden, T.; Lieberman, D.; Cheung, T.

    2012-03-01

    Pathogens could be inactivated via a light source coupled with a photosensitizing agent in photodynamic antimicrobial chemotherapy (PACT). This project studied the effect of non-homogenous substrate on cell colony. The non-homogeneity could be controlled by iron oxide nano-particles doping in porous glassy substrates such that each cell would experience tens of hot spots when illuminated with additional light source. The substrate non-homogeneity was characterized by Atomic Force Microscopy, Transmission Electron Microscopy and Extended X-Ray Absorption Fine Structure at Brookhaven Synchrotron Light Source. Microscopy images of cell motion were used to study the motility. Laboratory cell colonies on non-homogenous substrates exhibit reduced motility similar to those observed with sub-lethal PCAT treatment. Such motility reduction on non-homogenous substrate is interpreted as the presence of thermal stress. The studied pathogens included E. coli and Pseudomonas aeruginosa. Non-pathogenic microbes Bacillus subtilis was also studied for comparison. The results show that sub-lethal PACT could be effective with additional non-homogenous thermal stress. The use of non-uniform illumination on a homogeneous substrate to create thermal stress in sub-micron length scale is discussed via light correlation in propagation through random medium. Extension to sub-lethal PACT application complemented with thermal stress would be an appropriate application.

  11. Tracking in clutter and effects of thermal blooming on HEL beams

    Science.gov (United States)

    Belen'kii, Mikhail; Hughes, Kevin; Michailovich, Oleg; Rye, Vincent; Tannenbaum, Allen; Washburn, Don

    2005-08-01

    The tracking algorithm is presented that reduces the influence of the camera motion on the tracking performance. The algorithm uses a change detector. The target motion is described by parameterized optical flow. The flow parameters are estimated using Kalman filtering. The algorithm allows us to estimate the target motion without any bias associated with the camera motion. The effects of thermal blooming on high-energy laser beacon for air-to-ground directed energy system are evaluated. The laser fluence at the target and power in the bucket are evaluated for various tactical engagement scenarios and different atmospheric conditions. The critical laser power that can be efficiently transmitted through the atmosphere is evaluated. Two techniques for mitigating the effects of thermal blooming including a method based on pointing of a high energy beam "downwind" to correct for the thermal blooming tilt and focusing a high energy beam beyond the target range are evaluated. We found that the power in the bucket at the target at the optical axis of a high energy beam for tactical directed energy system increases about one order of magnitude due to correction of the thermal blooming tilt.

  12. The peak of thermoregulation effectiveness: Thermal biology of the Pyrenean rock lizard, Iberolacerta bonnali (Squamata, Lacertidae).

    Science.gov (United States)

    Ortega, Zaida; Mencía, Abraham; Pérez-Mellado, Valentín

    2016-02-01

    We studied, at 2200m altitude, the thermal biology of the Pyrenean rock lizard, Iberolacerta bonnali, in the glacial cirque of Cotatuero (National Park of Ordesa, Huesca, Spain). The preferred thermal range (PTR) of I. bonnali indicates that it is a cold-adapted ectotherm with a narrow PTR (29.20-32.77°C). However, its PTR (3.57°C) is twice as wide as other Iberolacerta lizards, which may be explained by its broader historical distribution. The studied area is formed by a mosaic of microhabitats which offer different operative temperatures, so that lizards have, throughout their entire daily period of activity, the opportunity to choose the most thermally suitable substrates. I. bonnali achieves an effectiveness of thermoregulation of 0.95, which makes it the highest value found to date among the Lacertidae, and one of the highest among lizards. Their relatively wide distribution, their wider PTR, and their excellent ability of thermoregulation, would make I. bonnali lizards less vulnerable to climate change than other species of Iberolacerta. Thanks to its difficult access, the studied area is not visited by a large number of tourists, as are other areas of the National Park. Thus, it is a key area for the conservation of the Pyrenean rock lizard. By shuttling between suitable microhabitats, lizards achieve suitable body temperatures during all day. However, such thermally suitable microhabitats should vary in other traits than thermal quality, such as prey availability or predation risk. Hence, it seems that these not-thermal traits are not constraining habitat selection and thermoregulation in this population. Therefore, future research in this population may study the causes that would lead lizards to prioritize thermoregulation to such extent in this population. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Effect of hygric and thermal properties of connecting layers on the performance of interior thermal insulation systems

    Science.gov (United States)

    Kočí, Václav; Jerman, Miloš; Fiala, Lukáš; Černý, Robert

    2017-11-01

    Interior thermal insulation systems represent often the only way of thermal protection, especially when historical buildings are taken into account. Since these systems face distrust due to frequent moisture failures, alternative solutions substituting the common water vapor barrier are being sought. In this paper, an assessment of hygrothermal performance of interior thermal insulation systems with purposely developed connecting layers is presented. Two types of mineral wools are connected to a sandstone masonry using two different connecting materials. The hygrothermal performance of the wall is obtained as a result of computational modelling with experimentally determined material parameters. Dynamic boundary conditions in the form of climatic data for Prague are used. The results indicate that the combination of permeable thermal insulation materials with investigated connecting layers have a positive influence on hygrothermal performance of the system as the moisture content is kept on very low level during a reference year. On the other hand, an increased attention should be paid to the protection of the masonry against excessive weather straining due to the absence of exterior thermal insulation.

  14. Feedback effect of human physical and psychological adaption on time period of thermal adaption in naturally ventilated building

    DEFF Research Database (Denmark)

    liu, weiwei; Huangfu, Hao; Xiong, Jing

    2014-01-01

    This study proposed a method to determine time period of thermal adaption for occupants in naturally ventilated building, and analyzed the synergistic and separate feedback effect of the physical and psychological adaption modes on the time period of thermal adaption. Using the method, the values...... indicated that the psychological adaption mode can speed up the process of thermal adaption to the variation in the outdoor climate condition. This study presented a new insight into the feedback from the thermal adaption modes to occupant thermal comfort.......This study proposed a method to determine time period of thermal adaption for occupants in naturally ventilated building, and analyzed the synergistic and separate feedback effect of the physical and psychological adaption modes on the time period of thermal adaption. Using the method, the values......, under the synergistic feedback effect of the physical and psychological adaption modes. The time period of thermal adaption increased to 13 days, if only the feedback effect of the physical adaption mode was accounted for. The difference between the two values of the time period of thermal adaption...

  15. The negative effect of starvation and the positive effect of mild thermal stress on thermal tolerance of the red flour beetle, Tribolium castaneum

    Science.gov (United States)

    Scharf, Inon; Wexler, Yonatan; MacMillan, Heath Andrew; Presman, Shira; Simson, Eddie; Rosenstein, Shai

    2016-04-01

    The thermal tolerance of a terrestrial insect species can vary as a result of differences in population origin, developmental stage, age, and sex, as well as via phenotypic plasticity induced in response to changes in the abiotic environment. Here, we studied the effects of both starvation and mild cold and heat shocks on the thermal tolerance of the red flour beetle, Tribolium castaneum. Starvation led to impaired cold tolerance, measured as chill coma recovery time, and this effect, which was stronger in males than females, persisted for longer than 2 days but less than 7 days. Heat tolerance, measured as heat knockdown time, was not affected by starvation. Our results highlight the difficulty faced by insects when encountering multiple stressors simultaneously and indicate physiological trade-offs. Both mild cold and heat shocks led to improved heat tolerance in both sexes. It could be that both mild shocks lead to the expression of heat shock proteins, enhancing heat tolerance in the short run. Cold tolerance was not affected by previous mild cold shock, suggesting that such a cold shock, as a single event, causes little stress and hence elicits only weak physiological reaction. However, previous mild heat stress led to improved cold tolerance but only in males. Our results point to both hardening and cross-tolerance between cold and heat shocks.

  16. The negative effect of starvation and the positive effect of mild thermal stress on thermal tolerance of the red flour beetle, Tribolium castaneum.

    Science.gov (United States)

    Scharf, Inon; Wexler, Yonatan; MacMillan, Heath Andrew; Presman, Shira; Simson, Eddie; Rosenstein, Shai

    2016-04-01

    The thermal tolerance of a terrestrial insect species can vary as a result of differences in population origin, developmental stage, age, and sex, as well as via phenotypic plasticity induced in response to changes in the abiotic environment. Here, we studied the effects of both starvation and mild cold and heat shocks on the thermal tolerance of the red flour beetle, Tribolium castaneum. Starvation led to impaired cold tolerance, measured as chill coma recovery time, and this effect, which was stronger in males than females, persisted for longer than 2 days but less than 7 days. Heat tolerance, measured as heat knockdown time, was not affected by starvation. Our results highlight the difficulty faced by insects when encountering multiple stressors simultaneously and indicate physiological trade-offs. Both mild cold and heat shocks led to improved heat tolerance in both sexes. It could be that both mild shocks lead to the expression of heat shock proteins, enhancing heat tolerance in the short run. Cold tolerance was not affected by previous mild cold shock, suggesting that such a cold shock, as a single event, causes little stress and hence elicits only weak physiological reaction. However, previous mild heat stress led to improved cold tolerance but only in males. Our results point to both hardening and cross-tolerance between cold and heat shocks.

  17. Experimental measurements of the thermal conductivity of ash deposits: Part 2. Effects of sintering and deposit microstructure

    Energy Technology Data Exchange (ETDEWEB)

    A. L. Robinson; S. G. Buckley; N. Yang; L. L. Baxter

    2000-04-01

    The authors report results from an experimental study that examines the influence of sintering and microstructure on ash deposit thermal conductivity. The measurements are made using a technique developed to make in situ, time-resolved measurements of the effective thermal conductivity of ash deposits formed under conditions that closely replicate those found in the convective pass of a commercial boiler. The technique is designed to minimize the disturbance of the natural deposit microstructure. The initial stages of sintering and densification are accompanied by an increase in deposit thermal conductivity. Subsequent sintering continues to densify the deposit, but has little effect on deposit thermal conductivity. SEM analyses indicates that sintering creates a layered deposit structure with a relatively unsintered innermost layer. They hypothesize that this unsintered layer largely determines the overall deposit thermal conductivity. A theoretical model that treats a deposit as a two-layered material predicts the observed trends in thermal conductivity.

  18. Thermal effects in Yb-doped double-cladding Distributed Modal Filtering rod-type fibers

    DEFF Research Database (Denmark)

    Coscelli, Enrico; Poli, Federica; Jørgensen, Mette Marie

    2012-01-01

    element method. A DMF fiber design, which is single-mode in the 1030 nm–1064 nm region, is considered, and the effects of thermal load on the transmission characteristics are evaluated. Results show a blue-shift of the single-mode window and the single-mode bandwidth narrowing as the absorbed pump power......The effects of thermally-induced refractive index change in Yb-doped Distributed Modal Filtering (DMF) photonic crystal fibers are investigated, where high-order mode suppression is obtained by resonant coupling with high index elements in the cladding. The temperature distribution on the fiber...... cross-section is calculated with an analytical model, for different pump power values. The consequent refractive index change, due to the thermo-optical effect, is applied to the cross-section of the DMF fiber, whose guiding properties are studied with a full-vector modal solver based on the finite...

  19. Application of a model to investigate the effective thermal conductivity of randomly packed fusion pebble beds

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaoliang; Zheng, Jie; Chen, Hongli, E-mail: hlchen1@ustc.edu.cn

    2016-05-15

    In our precious study, a prediction model, which calculates the effective thermal conductivity k{sub eff} of mono-sized pebble beds, has been developed and validated. Based on this model, here the effects of these influencing factors such as pebble size, thermal radiation, contact area, filling gas, gas flow, gas pressure, etc. on the k{sub eff} of randomly packed fusion pebble beds are studied and analyzed. The pebble beds investigated include Li{sub 4}SiO{sub 4}, Li{sub 2}ZrO{sub 3}, Li{sub 2}TiO{sub 3}, Li{sub 2}O, Be and BeO pebble beds. In the current study, many important and meaningful conclusions are derived and some of them are similar to the existing research results. Particularly, some critters that under which conditions the effect of some influencing factors can be neglected or should be considered are also presented.

  20. Underground physics and the barometric pumping effect observed for thermal neutron flux underground

    Science.gov (United States)

    Stenkin, Yu. V.; Alekseenko, V. V.; Gromushkin, D. M.; Sulakov, V. P.; Shchegolev, O. B.

    2017-05-01

    It is known that neutron background is a major problem for low-background experiments carrying out underground, such as dark matter search, double-beta decay searches and other experiments known as Underground Physics. We present here some results obtained with the en-detector of 0.75 m2, which is running for more than 4 years underground at a depth of 25 m water equivalent in Skobeltsyn Institute of Nuclear Physics, Moscow State University. Some spontaneous increases in thermal neutron flux up to a factor of 3 were observed in delayed anti-correlation with barometric pressure. The phenomenon can be explained by the radon barometric pumping effect resulting in similar effect in neutron flux being produced in (α, n)-reactions by alpha-decays of radon and its daughters in surrounding rock. This is the first demonstration of the barometric pumping effect observed in thermal neutron flux underground.

  1. Effect of non-thermal atmospheric pressure plasma jet on human breast cancer cells

    Science.gov (United States)

    Mirpour, Shahriar; Nikkhah, Maryam; Pirouzmand, Somaye; Ghomi, Hamid Reza

    2012-10-01

    Nowadays, Non-thermal plasma enjoy a wide range of applications in biomedical fields such as Sterilization, Wound healing, Cancer treatment and etc. The aim of this paper is to study the effect of non-thermal atmospheric pressure plasma jet on breast cancer (MCF-7) cells. In this regard the effect of plasma on death of the cancer cells are explored experimentally. The plasma in this discharge is created by pulsed dc high voltage power supply with repetition rate of several tens of kilohertz which led to the inductively coupled plasma. The pure helium gas were used for formation of the plasma jet. MTT assay were used for quantification of death cells. The results showed that the cells death rate increase with plasma exposure time. This study confirm that plasma jet have significant effect on treatment of human breast cancer cells.

  2. Effect of high pressure on rheological and thermal properties of quinoa and maize starches.

    Science.gov (United States)

    Li, Guantian; Zhu, Fan

    2018-02-15

    Quinoa starch has small granules with relatively low gelatinization temperatures and amylose content. High hydrostatic pressure (HHP) is a non-thermal technique for food processing. In this study, effects of HHP up to 600MPa on physical properties of quinoa starch were studied and compared with those of a normal maize starch. Both starches gelatinized at 500 and 600MPa. The pressure of 600MPa completely gelatinized quinoa starch as revealed by thermal analysis. Dynamic rheological analysis showed that HHP improved the gel stability of both starches during cooling. HHP had little effects on amylopectin recrystallization and gel textural properties of starch. Overall, quinoa starch was more susceptible to HHP than maize starch. The effects of HHP on some rheological properties such as frequency dependence were different between these two types of starches. The differences could be attributed to the different composition, granular and chemical structures of starch, and the presence of granule remnants. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Analytic determination of the effective thermal conductivity of PEM fuel cell gas diffusion layers

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, E.; Bahrami, M.; Djilali, N. [Department of Mechanical Engineering and the Institute for Integrated Energy Systems, University of Victoria, Victoria, BC V8W 3P6 (Canada)

    2008-04-15

    Accurate information on the temperature field and associated heat transfer rates are particularly important in devising appropriate heat and water management strategies in proton exchange membrane (PEM) fuel cells. An important parameter in fuel cell performance analysis is the effective thermal conductivity of the gas diffusion layer (GDL). Estimation of the effective thermal conductivity is complicated because of the random nature of the GDL micro structure. In the present study, a compact analytical model for evaluating the effective thermal conductivity of fibrous GDLs is developed. The model accounts for conduction in both the solid fibrous matrix and in the gas phase; the spreading resistance associated with the contact area between overlapping fibers; gas rarefaction effects in microgaps; and salient geometric and mechanical features including fiber orientation and compressive forces due to cell/stack clamping. The model predictions are in good agreement with existing experimental data over a wide range of porosities. Parametric studies are performed using the proposed model to investigate the effect of bipolar plate pressure, aspect ratio, fiber diameter, fiber angle, and operating temperature. (author)

  4. Finite-size effects on molecular dynamics interfacial thermal-resistance predictions

    Science.gov (United States)

    Liang, Zhi; Keblinski, Pawel

    2014-08-01

    Using molecular dynamics simulations, we study the role of finite size effects on the determination of interfacial thermal resistance between two solids characterized by high phonon mean free paths. In particular, we will show that a direct, heat source-sink method leads to strong size effect, associated with ballistic phonon transport to and from, and specular reflections at the simulation domain boundary. Lack of proper account for these effects can lead to incorrect predictions about the role of interfacial bonding and structure on interfacial thermal resistance. We also show that the finite size effect can be dramatically reduced by introduction of rough external boundaries leading to diffuse phonon scattering, as explicitly demonstrated by phonon wave-packet simulations. Finally, we demonstrate that when careful considerations are given to the effects associated with the finite heat capacity of the simulation domains and phonon scattering from the external surfaces, a size-independent interfacial resistance can be properly extracted from the time integral of the correlation function of heat power across the interface. Our work demonstrates that reliable and consistent values of the interfacial thermal resistance can be obtained by equilibrium and nonequilibrium methods with a relatively small computational cost.

  5. Analytic determination of the effective thermal conductivity of PEM fuel cell gas diffusion layers

    Science.gov (United States)

    Sadeghi, E.; Bahrami, M.; Djilali, N.

    Accurate information on the temperature field and associated heat transfer rates are particularly important in devising appropriate heat and water management strategies in proton exchange membrane (PEM) fuel cells. An important parameter in fuel cell performance analysis is the effective thermal conductivity of the gas diffusion layer (GDL). Estimation of the effective thermal conductivity is complicated because of the random nature of the GDL micro structure. In the present study, a compact analytical model for evaluating the effective thermal conductivity of fibrous GDLs is developed. The model accounts for conduction in both the solid fibrous matrix and in the gas phase; the spreading resistance associated with the contact area between overlapping fibers; gas rarefaction effects in microgaps; and salient geometric and mechanical features including fiber orientation and compressive forces due to cell/stack clamping. The model predictions are in good agreement with existing experimental data over a wide range of porosities. Parametric studies are performed using the proposed model to investigate the effect of bipolar plate pressure, aspect ratio, fiber diameter, fiber angle, and operating temperature.

  6. Thermal motion in proteins: Large effects on the time-averaged interaction energies

    Energy Technology Data Exchange (ETDEWEB)

    Goethe, Martin, E-mail: martingoethe@ub.edu; Rubi, J. Miguel [Departament de Física Fonamental, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Fita, Ignacio [Institut de Biologia Molecular de Barcelona, Baldiri Reixac 10, 08028 Barcelona (Spain)

    2016-03-15

    As a consequence of thermal motion, inter-atomic distances in proteins fluctuate strongly around their average values, and hence, also interaction energies (i.e. the pair-potentials evaluated at the fluctuating distances) are not constant in time but exhibit pronounced fluctuations. These fluctuations cause that time-averaged interaction energies do generally not coincide with the energy values obtained by evaluating the pair-potentials at the average distances. More precisely, time-averaged interaction energies behave typically smoother in terms of the average distance than the corresponding pair-potentials. This averaging effect is referred to as the thermal smoothing effect. Here, we estimate the strength of the thermal smoothing effect on the Lennard-Jones pair-potential for globular proteins at ambient conditions using x-ray diffraction and simulation data of a representative set of proteins. For specific atom species, we find a significant smoothing effect where the time-averaged interaction energy of a single atom pair can differ by various tens of cal/mol from the Lennard-Jones potential at the average distance. Importantly, we observe a dependency of the effect on the local environment of the involved atoms. The effect is typically weaker for bulky backbone atoms in beta sheets than for side-chain atoms belonging to other secondary structure on the surface of the protein. The results of this work have important practical implications for protein software relying on free energy expressions. We show that the accuracy of free energy expressions can largely be increased by introducing environment specific Lennard-Jones parameters accounting for the fact that the typical thermal motion of protein atoms depends strongly on their local environment.

  7. Ocean acidification has little effect on developmental thermal windows of echinoderms from Antarctica to the tropics.

    Science.gov (United States)

    Karelitz, Sam E; Uthicke, Sven; Foo, Shawna A; Barker, Mike F; Byrne, Maria; Pecorino, Danilo; Lamare, Miles D

    2017-02-01

    As the ocean warms, thermal tolerance of developmental stages may be a key driver of changes in the geographical distributions and abundance of marine invertebrates. Additional stressors such as ocean acidification may influence developmental thermal windows and are therefore important considerations for predicting distributions of species under climate change scenarios. The effects of reduced seawater pH on the thermal windows of fertilization, embryology and larval morphology were examined using five echinoderm species: two polar (Sterechinus neumayeri and Odontaster validus), two temperate (Fellaster zelandiae and Patiriella regularis) and one tropical (Arachnoides placenta). Responses were examined across 12-13 temperatures ranging from -1.1 °C to 5.7 °C (S. neumayeri), -0.5 °C to 10.7 °C (O. validus), 5.8 °C to 27 °C (F. zelandiae), 6.0 °C to 27.1 °C (P. regularis) and 13.9 °C to 34.8 °C (A. placenta) under present-day and near-future (2100+) ocean acidification conditions (-0.3 pH units) and for three important early developmental stages 1) fertilization, 2) embryo (prehatching) and 3) larval development. Thermal windows for fertilization were broad and were not influenced by a pH decrease. Embryological development was less thermotolerant. For O. validus, P. regularis and A. placenta, low pH reduced normal development, albeit with no effect on thermal windows. Larval development in all five species was affected by both temperature and pH; however, thermal tolerance was not reduced by pH. Results of this study suggest that in terms of fertilization and development, temperature will remain as the most important factor influencing species' latitudinal distributions as the ocean continues to warm and decrease in pH, and that there is little evidence of a synergistic effect of temperature and ocean acidification on the thermal control of species ranges. © 2016 John Wiley & Sons Ltd.

  8. Effect of particle size on the thermo-optic properties of gold nanofluids – A thermal lens study

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, B. Rajesh; Basheer, N. Shemeena; Kurian, Achamma [Photonics Lab, Department of Physics, Catholicate College, Pathanamthitta (India); George, Sajan D., E-mail: sajan.george@manipal.edu [Centre for Atomic and Molecular Physics, Manipal University, Manipal, Karnataka (India)

    2014-01-28

    Spherical gold nanoparticles having particle size in the range 30 to 50 nm are prepared using citrate reduction of gold chloride trihydrate in water. The influence of particle size on the thermal diffusivity value of gold nanofluid is measured using dual beam thermal lens technique. The present study shows that the particle size influences the effective thermal diffusivity value of the nanofluid substantially and the value decreases with decrease in particle size for the investigated samples.

  9. Fundamental-frequency and load-varying thermal cycles effects on lifetime estimation of DFIG power converter

    DEFF Research Database (Denmark)

    Zhang, Guanguan; Zhou, Dao; Yang, Jian

    2017-01-01

    In respect to a Doubly-Fed Induction Generator (DFIG) system, its corresponding time scale varies from microsecond level of power semiconductor switching to second level of the mechanical response. In order to map annual thermal profile of the power semiconductors, different approaches have been...... adopted to handle the fundamental-frequency thermal cycles and load-varying thermal cycles. Their effects on lifetime estimation of the power device in the Back-to-Back (BTB) power converter are evaluated....

  10. The Effect of Booster-Mirror Reflector on the Thermal Performance of a Truncated Pyramid Solar Thermal Cooker

    OpenAIRE

    I. L. Mohammed; Aliyu, M. M.

    2014-01-01

    In this paper, the results and analysis of the performance of a truncated pyramid solar thermal cooker under two conditions are presented: booster-mirror reflector covered with black cloth, and booster-mirror reflector exposed to solar radiation. Results of the thermal performance tests show respective stagnation absorber plate temperatures of 145 oC and 137 oC. First/Second Figures of Merit are 0.120/0.346 and 0.125/0.400 respectively. The total heating times of 5.2 kg of wate...

  11. A prediction model for the effective thermal conductivity of nanofluids considering agglomeration and the radial distribution function of nanoparticles

    Science.gov (United States)

    Zheng, Z. M.; Wang, B.

    2018-01-01

    Conventional heat transfer fluids usually have low thermal conductivity, limiting their efficiency in many applications. Many experiments have shown that adding nanosize solid particles to conventional fluids can greatly enhance their thermal conductivity. To explain this anomalous phenomenon, many theoretical investigations have been conducted in recent years. Some of this research has indicated that the particle agglomeration effect that commonly occurs in nanofluids should play an important role in such enhancement of the thermal conductivity, while some have shown that the enhancement of the effective thermal conductivity might be accounted for by the structure of nanofluids, which can be described using the radial distribution function of particles. However, theoretical predictions from these studies are not in very good agreement with experimental results. This paper proposes a prediction model for the effective thermal conductivity of nanofluids, considering both the agglomeration effect and the radial distribution function of nanoparticles. The resulting theoretical predictions for several sets of nanofluids are highly consistent with experimental data.

  12. Investigation of non-thermal plasma effects on lung cancer cells within 3D collagen matrices

    Science.gov (United States)

    Karki, Surya B.; Thapa Gupta, Tripti; Yildirim-Ayan, Eda; Eisenmann, Kathryn M.; Ayan, Halim

    2017-08-01

    Recent breakthroughs in plasma medicine have identified a potential application for the non-thermal plasma in cancer therapy. Most studies on the effects of non-thermal plasma on cancer cells have used traditional two-dimensional (2D) monolayer cell culture. However, very few studies are conducted employing non-thermal plasma in animal models. Two dimensional models do not fully mimic the three-dimensional (3D) tumor microenvironment and animal models are expensive and time-consuming. Therefore, we used 3D collagen matrices that closely resemble the native geometry of cancer tissues and provide more physiologically relevant results than 2D models, while providing a more cost effective and efficient precursor to animal studies. We previously demonstrated a role for non-thermal plasma application in promoting apoptotic cell death and reducing the viability of A549 lung adenocarcinoma epithelial cells cultured upon 2D matrices. In this study, we wished to determine the efficacy of non-thermal plasma application in driving apoptotic cell death of A549 lung cancer cells encapsulated within a 3D collagen matrix. The percentage of apoptosis increased as treatment time increased and was time dependent. In addition, the anti-viability effect of plasma was demonstrated. Twenty-four hours post-plasma treatment, 38% and 99% of cell death occurred with shortest (15 s) and longest treatment time (120 s) respectively at the plasma-treated region. We found that plasma has a greater effect on the viability of A549 lung cancer cells on the superficial surface of 3D matrices and has diminishing effects as it penetrates the 3D matrix. We also identified the nitrogen and oxygen species generated by plasma and characterized their penetration in vertical and lateral directions within the 3D matrix from the center of the plasma-treated region. Therefore, the utility of non-thermal dielectric barrier discharge plasma in driving apoptosis and reducing the viability of lung cancer cells

  13. Effects of Magnetite Aggregate and Steel Powder on Thermal Conductivity and Porosity in Concrete for Nuclear Power Plant

    Directory of Open Access Journals (Sweden)

    Han-Seung Lee

    2016-01-01

    Full Text Available Among many engineering advantages in concrete, low thermal conductivity is an attractive property. Concrete has been widely used for nuclear vessels and plant facilities for its excellent radiation shielding. The heat isolation through low thermal conductivity is actually positive for nuclear power plant concrete; however the property may cause adverse effect when fires and melt-down occur in nuclear vessel since cooling down from outer surface is almost impossible due to very low thermal conductivity. If concrete containing atomic reactor has higher thermal conductivity, the explosion risk of conductive may be partially reduced. This paper presents high thermally conductive concrete development. For the work, magnetite with varying replacements of normal aggregates and steel powder of 1.5% of volume are considered, and the equivalent thermal conductivity is evaluated. Only when the replacement ratio goes up to 30%, thermal conductivity increases rapidly to 2.5 times. Addition of steel powder is evaluated to be effective by 1.08~1.15 times. In order to evaluate the improvement of thermal conductivity, several models like ACI, DEMM, and MEM are studied, and their results are compared with test results. In the present work, the effects of steel powder and magnetite aggregate are studied not only for strength development but also for thermal behavior based on porosity.

  14. The effect of added fullness and ventilation holes in T-shirt design on thermal comfort.

    Science.gov (United States)

    Ho, Chupo; Fan, Jintu; Newton, Edward; Au, Raymond

    2011-04-01

    This paper reports on an experimental investigation on the effect of added fullness and ventilation holes in T-shirt design on clothing comfort measured in terms of thermal insulation and moisture vapour resistance. Four T-shirts in four different sizes (S, M, L, XL) were cut under the traditional sizing method while another (F-1) was cut with specially added fullness to create a 'flared' drape. A thermal manikin 'Walter' was used to measure the thermal insulation and moisture vapour resistance of the T-shirts in a chamber with controlled temperature, relative humidity and air velocity. The tests included four conditions: manikin standing still in the no-wind and windy conditions and walking in the no-wind and windy condition. It was found that adding fullness in the T-shirt design (F-1) to create the 'flared' drape can significantly reduce the T-shirt's thermal insulation and moisture vapour resistance under walking or windy conditions. Heat and moisture transmission through the T-shirt can be further enhanced by creating small apertures on the front and back of the T-shirt with specially added fullness. STATEMENT OF RELEVANCE: The thermal comfort of the human body is one of the key issues in the study of ergonomics. When doing exercise, a human body will generate heat, which will eventually result in sweating. If heat and moisture are not released effectively from the body, heat stress may occur and the person's performance will be negatively affected. Therefore, contemporary athletic T-shirts are designed to improve the heat and moisture transfer from the wearer. Through special cutting, such athletic T-shirts can be designed to improve the ventilation of the wearer.

  15. The Thermal Proximity Effect: A New Probe of the He II Reionization History and Quasar Lifetime

    Science.gov (United States)

    Khrykin, I. S.; Hennawi, J. F.; McQuinn, M.

    2017-04-01

    Despite decades of effort, the timing and duration of He II reionization and the properties of the quasars believed to drive it are still not well constrained. We present a new method to study both via the thermal proximity effect—the heating of the intergalactic medium (IGM) around quasars when their radiation doubly ionizes helium. We post-process hydrodynamical simulations with 1D radiative transfer and study how the thermal proximity effect depends on the He II fraction, {x}{He{{II}},0}, which prevailed in the IGM before the quasar turned on, and the quasar lifetime {t}{{Q}}. We find that the amplitude of the temperature boost in the quasar environment depends on {x}{He{{II}},0}, with a characteristic value of {{Δ }}T≃ {10}4 {{K}} for {x}{He{{II}},0}=1.0, whereas the size of the thermal proximity zone is sensitive to {t}{{Q}}, with typical sizes of ≃ 100 {cMpc} for {t}{{Q}}={10}8 {yr}. This temperature boost increases the thermal broadening of H I absorption lines near the quasar. We introduce a new Bayesian statistical method based on measuring the Lyα forest power spectrum as a function of distance from the quasar, and demonstrate that the thermal proximity effect should be easily detectable. For a mock data set of 50 quasars at z≃ 4, we predict that one can measure {x}{He{{II}},0} to an (absolute) precision ≈ 0.04 and {t}{{Q}} to a precision of ≈ 0.1 dex. By applying our formalism to existing high-resolution Lyα forest spectra, one should be able to reconstruct the He II reionization history, providing a global census of hard photons in the high-z universe.

  16. Effect of vacuum and thermal shock on laser treatment of Trichophyton rubrum (toenail fungus)

    Science.gov (United States)

    Aguilar, Guillermo; Sun, Feng; Carlier, Pierre; Young, Erica; Hennings, David; González, F. Javier

    2010-02-01

    The eradication of Trichophyton rubrum has been attempted via laser irradiation because it could result advantageous relative to current clinical therapies. Anticipating that the necessary thermal effects could unintentionally damage the underlying toe dermal layer, we have explored two auxiliary approaches: (a) laser irradiation under vacuum pressure, with and without water dousing and, (b) cooling followed by laser heating (thermal shock). The rationale is that at low pressures, the temperature necessary to achieve water evaporation/boiling is significantly reduced, thus requiring lower fluences. Similarly, a thermal shock induced by cooling followed by laser irradiation may require lower fluences to achieve fungus necrosis. For all experiments presented we use a Cooltouch, model CT3 plus, 1320 nm laser to irradiate fungi colonies. The vacuum pressure experiments exposed fungi colonies to a subatmospheric pressure of 84.7 kPa (25 inHg) with and without water dousing for 5 min, followed by irradiation with 4.0 J/cm2 fluence and 40-90 J total energies. The thermal shock experiments consisted of three sections at 4.8 J/cm2: cooling the fungus to 0 °C at 0.39 °C/min and then irradiating to 45-60 °C cooling to -20 °C at 1.075 °C/min and irradiating to 45 °C and cooling to -20 °C at 21.5 °C/min and irradiating to 45 °C. Fungus growth rate over a 1-week period assessed the feasibility of these procedures. Results indicated both approaches hamper the growth rate of fungi colonies relative to untreated control samples, especially water dousing under vacuum conditions and slow cooling rate preceding irradiation for thermal shock effect.

  17. Thermal storage in a heat pump heated living room floor for urban district power balancing - effects on thermal comfort, energy loss and costs for residents

    NARCIS (Netherlands)

    van Leeuwen, Richard Pieter; de Wit, J.B.; Fink, J.; Smit, Gerardus Johannes Maria

    2014-01-01

    For the Dutch smart grid demonstration project Meppelenergie, the effects of controlled thermal energy storage within the floor heating structure of a living room by a heat pump are investigated. Storage possibilities are constrained by room operative and floor temperatures. Simulations indicate

  18. The Yarkovsky-Schach Thermal Effect on Lageos Satellites and its Modelling

    Science.gov (United States)

    Lucchesi, D. M.; Pavlis, E. C.; Ciufolini, I.; Peron, R.

    2003-04-01

    Thermal thrust effects are thermal drag effects due to an anisotropic emission of thermal radiation from the satellite surface. This radiation, carrying away linear momentum, causes recoil accelerations along a given direction. Such radiation comes from the anisotropic distribution of temperature across the satellite surface, arising in turn from the non-uniform absorption of the incoming radiation. The larger contribution is due to the visible solar radiation - the so-called Yarkovsky-Schach effect - modulated during the eclipse passages through Earth's shadow. The acceleration produced is directed along the satellite spin axis if the satellite is rapidly spinning. Otherwise, both a spin component and an equatorial component of the acceleration will be present. The solar Yarkovsky-Schach perturbative effects on the orbital parameters of passive, cannonball-shape satellites such as LAGEOS, have been studied extensively in the past. To our knowledge though, the models describing this perturbation were never included into the orbit determination programs used for geodesy and geodynamics. Our recent analyses of seven years of LAGEOS II perigee residuals produced the characteristic signature of the Yarkovsky-Schach perturbation and our model of the effect clearly reproduces the perigee residuals, as well as those of the eccentricity vector. In the present work we have included this thermal perturbation in the GEODYN II orbit determination and data analysis package. We tested the perturbation using different periods of laser tracking data and different arc-lengths and with special consideration for the satellite spin axis evolution model. We will present results from our analyses of the LAGEOS orbital residuals, both in the time and frequency domain.

  19. Thermal and microstructural effects of nanosecond pulsed Nd:YAG laser irradiation on tooth root surface

    Science.gov (United States)

    Wilder-Smith, Petra B. B.; Arrastia-Jitosho, Anna-Marie A.; Grill, G.; Liaw, Lih-Huei L.; Berns, Michael W.

    1995-05-01

    Plaque, calculus and altered cementum removal by scaling and root planing is a fundamental procedure in periodontal treatment. However, the residual smear layer contains cytotoxic and inflammatory mediators which adversely affect healing. Chemical smear layer removal is also problematic. In previous investigations effective smear layer removal was achieved using long pulsed irradiation at 1.06 (mu) . However, laser irradiation was not adequate as an alternative to scaling and root planing procedures and concurrent temperature rises exceeded thermal thresholds for pulpal and periodontal safety. It was the aim of this study to determine whether nanosecond pulsed irradiation at 1.06 (mu) could be used as an alternative or an adjunct to scaling and root planing. Sixty freshly extracted teeth were divided as follows: 5 control, 5 root planed only, 25 irradiated only, 25 root planed and irradiated. Irradiation was performed at fluences of 0.5 - 2.7 J/cm2, total energy densities of 12 - 300 J/cm2, frequencies of 2 - 10 Hz using the Medlite (Continuum) laser. Irradiation-induced thermal events were recorded using a thermocouple within the root canal and a thermal camera to monitor surface temperatures. SEM demonstrated effective smear layer removal with minimal microstructural effects. Surface temperatures increased minimally (< 3 C) at all parameters, intrapulpal temperature rises remained below 4 C at 2 and 5 Hz, F < 0.5 J/cm2. Without prior scaling and root planing, laser effects did not provide an adequately clean root surface.

  20. In situ Weak Magnetic-Assisted Thermal Stress Field Reduction Effect in Laser Welding

    Science.gov (United States)

    Liang, Lvjie; Pang, Shengyong; Shao, Xinyu; Wang, Chunming; Jiang, Ping; Chen, Xin

    2018-01-01

    For decades, post-welding magnetic treatment has been used to reduce residual stress of welds by improving the crystal structure of solid-state welds. In this paper, we propose a new magnetic treatment method, which can reduce the time-dependent thermal stress field in situ and reduce the final residual stress of welds by simply exerting an assisted weak magnetic field perpendicular to the welding direction and workpiece during laser welding. A new finite-element model is developed to understand the thermal-mechanical physical process of the magnetic-assisted laser welding. For the widely used 304 austenite stainless steel, we theoretically observed that this method can reduce around 10 pct of the time-dependent thermal stress field, and finally reduce approximately 20 MPa of residual stress near the heat-affected zone with a 415-mT magnetic field for typical welding process parameters. A new mechanism based on magneto-fluid dynamics is proposed to explain the theoretical predications by combining high-speed imaging experiments of the transient laser welding process. The developed method is very simple but surprisingly effective, which opens new avenues for thermal stress reduction in laser welding of metals, particularly heat-sensitive metallic materials.

  1. Effects of thermal treatment and sonication on quality attributes of Chokanan mango (Mangifera indica L.) juice.

    Science.gov (United States)

    Santhirasegaram, Vicknesha; Razali, Zuliana; Somasundram, Chandran

    2013-09-01

    Ultrasonic treatment is an emerging food processing technology that has growing interest among health-conscious consumers. Freshly squeezed Chokanan mango juice was thermally treated (at 90 °C for 30 and 60s) and sonicated (for 15, 30 and 60 min at 25 °C, 40 kHz frequency, 130 W) to compare the effect on microbial inactivation, physicochemical properties, antioxidant activities and other quality parameters. After sonication and thermal treatment, no significant changes occurred in pH, total soluble solids and titratable acidity. Sonication for 15 and 30 min showed significant improvement in selected quality parameters except color and ascorbic acid content, when compared to freshly squeezed juice (control). A significant increase in extractability of carotenoids (4-9%) and polyphenols (30-35%) was observed for juice subjected to ultrasonic treatment for 15 and 30 min, when compared to the control. In addition, enhancement of radical scavenging activity and reducing power was observed in all sonicated juice samples regardless of treatment time. Thermal and ultrasonic treatment exhibited significant reduction in microbial count of the juice. The results obtained support the use of sonication to improve the quality of Chokanan mango juice along with safety standard as an alternative to thermal treatment. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Effect of deformation on the thermal conductivity of granular porous media with rough grain surface

    Science.gov (United States)

    Askari, Roohollah; Hejazi, S. Hossein; Sahimi, Muhammad

    2017-08-01

    Heat transfer in granular porous media is an important phenomenon that is relevant to a wide variety of problems, including geothermal reservoirs and enhanced oil recovery by thermal methods. Resistance to flow of heat in the contact area between the grains strongly influences the effective thermal conductivity of such porous media. Extensive experiments have indicated that the roughness of the grains' surface follows self-affine fractal stochastic functions, and thus, the contact resistance cannot be accounted for by models based on smooth surfaces. Despite the significance of rough contact area, the resistance has been accounted for by a fitting parameter in the models of heat transfer. In this Letter we report on a study of conduction in a packing of particles that contains a fluid of a given conductivity, with each grain having a rough self-affine surface, and is under an external compressive pressure. The deformation of the contact area depends on the fractal dimension that characterizes the grains' rough surface, as well as their Young's modulus. Excellent qualitative agreement is obtained with experimental data. Deformation of granular porous media with grains that have rough self-affine fractal surface is simulated. Thermal contact resistance between grains with rough surfaces is incorporated into the numerical simulation of heat conduction under compressive pressure. By increasing compressive pressure, thermal conductivity is enhanced more in the grains with smoother surfaces and lower Young's modulus. Excellent qualitative agreement is obtained with the experimental data.

  3. Thermal stress analysis method considering geometric effect of risers in sand mold casting process

    Directory of Open Access Journals (Sweden)

    S. Y. Kwak

    2014-11-01

    Full Text Available Solidification and fluid flow analysis using computer simulation is a current common practice. There is also a high demand for thermal stress analysis in the casting process because casting engineers want to control the defects related to thermal stresses, such as large deformation and crack generation during casting. The riser system is an essential part of preventing the shrinkage defects in the casting process, and it has a great influence on thermal phenomena. The analysis domain is dramatically expanded by attaching the riser system to a casting product due to its large volume, and it makes FEM mesh generation difficult. However, it is difficult to study and solve the above proposed problem caused by riser system using traditional analysis methods which use single numerical method such as FEM or FDM. In this paper, some research information is presented on the effects of the riser system on thermal stress analysis using a FDM/FEM hybrid method in the casting process simulation. The results show the optimal conditions for stress analysis of the riser model in order to save computation time and memory resources.

  4. Effect of molecular structure on the thermal stability of amorphous and semicrystalline poly(lactic acid)

    Science.gov (United States)

    Aou, Kaoru

    Emphasizing on the effect of molecular structure, the issues surrounding the thermal stability amorphous and crystalline states of poly(lactic acid), or PLA, are explored. Enthalpic relaxation, which correlates with physical aging, is investigated for PLA of different tacticities, and we find that a decreased number of configurational defects in the polymer backbone leads to a smaller Kohlrausch-Williams-Watts exponent. On the other hand, specific volume, or equivalently density, does not relate simply to enthalpic stability when comparing the alpha and stereocomplex forms of PLA crystals. Although the a crystal has the higher density, molecular interactions, as inferred from vibrational spectroscopy and molecular modeling, are stronger in the stereocomplex, a trend consistent with a higher enthalpy of fusion. The methyl-methyl and carbonyl-carbonyl interactions are the main contributors to the alpha crystal thermal stability, whereas the methyl-methyl and carbonyl-to-alpha-hydrogen interactions are the important interactions for the thermal stability of the stereocomplex. In addition, good correlation between the post-Tg exotherm and fiber shrinkage can be explained using spectroscopic and calorimetric means. We find that fiber thermal stability is not achieved when crystallizable chains remain largely uncrystallized. During processing, if crystallization is not completed before vitrification sets in, fiber shrinkage will take place, followed by crystallization enhanced due to pre-existing crystallites from processing.

  5. Effect of thermal deformation on giant magnetoresistance of flexible spin valves grown on polyvinylidene fluoride membranes

    Science.gov (United States)

    Luping, Liu; Qingfeng, Zhan; Xin, Rong; Huali, Yang; Yali, Xie; Xiaohua, Tan; Run-wei, Li

    2016-07-01

    We fabricated flexible spin valves on polyvinylidene fluoride (PVDF) membranes and investigated the influence of thermal deformation of substrates on the giant magnetoresistance (GMR) behaviors. The large magnetostrictive Fe81Ga19 (FeGa) alloy and the low magnetostrictive Fe19Ni81 (FeNi) alloy were selected as the free and pinned ferromagnetic layers. In addition, the exchange bias (EB) of the pinned layer was set along the different thermal deformation axes α 31 or α 32 of PVDF. The GMR ratio of the reference spin valves grown on Si intrinsically increases with lowering temperature due to an enhancement of spontaneous magnetization. For flexible spin valves, when decreasing temperature, the anisotropic thermal deformation of PVDF produces a uniaxial anisotropy along the α 32 direction, which changes the distribution of magnetic domains. As a result, the GMR ratio at low temperature for spin valves with EB∥ α 32 becomes close to that on Si, but for spin valves with EB∥ α 31 is far away from that on Si. This thermal effect on GMR behaviors is more significant when using magnetostrictive FeGa as the free layer. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374312, 51401230, 51522105, and 51471101) and the Ningbo Science and Technology Innovation Team, China (Grant No. 2015B11001).

  6. Thermal remote sensing of estuarine spatial dynamics: Effects of bottom-generated vertical mixing

    Science.gov (United States)

    Marmorino, G. O.; Smith, G. B.

    2008-07-01

    In a recent paper, Hedger, R.D., Malthus, T.J., Folkard, A.M., Atkinson, P.M. [2007. Spatial dynamics of estuarine water surface temperature from airborne remote sensing. Estuarine, Coastal and Shelf Science 71, 608-615] demonstrate that airborne thermal remote sensing shows great potential for monitoring estuarine dynamics and surface currents. One aspect needing further attention is the impact of bottom-generated vertical mixing as this can create both stationary thermal features as well as thermal patterns that advect with the flow. This dual effect is illustrated using airborne infrared imagery of a mixing front having an embedded pattern of thermal boils. The boils are several meters in diameter (in water less than 4 m deep) and are ˜0.2 °C cooler than the ambient water surface. Time sequential imagery that captures the movement of individual boils as well as their growth rate can be used to deduce both the near-surface current and the intensity of turbulent mixing.

  7. EFFECTS OF IRRADIATION ON THERMAL CONDUCTIVITY OF ALLOY 690 AT LOW NEUTRON FLUENCE

    Directory of Open Access Journals (Sweden)

    WOO SEOG RYU

    2013-04-01

    Full Text Available Alloy 690 has been selected as a steam generator tubing material for SMART owing to a near immunity to primary water stress corrosion cracking. The steam generators of SMART are faced with a neutron flux due to the integrated arrangement inside a reactor vessel, and thus it is important to know the irradiation effects of the thermal conductivity of Alloy 690. Alloy 690 was irradiated at HANARO to fluences of (0.7−28 × 1019n/cm2 (E>0.1MeV at 250°C, and its thermal conductivity was measured using the laser-flash equipment in the IMEF. The thermal conductivity of Alloy 690 was dependent on temperature, and it was a good fit to the Smith-Palmer equation, which modified the Wiedemann-Franz law. The irradiation at 250°C did not degrade the thermal conductivity of Alloy 690, and even showed a small increase (1% at fluences of (0.7∼28 × 1019n/cm2 (E>0.1MeV.

  8. Effect of Thermal Annealing on Machining-Induced Residual Stresses in Inconel 718

    Science.gov (United States)

    Madariaga, A.; Aperribay, J.; Arrazola, P. J.; Esnaola, J. A.; Hormaetxe, E.; Garay, A.; Ostolaza, K.

    2017-08-01

    Nickel-based alloys are widely employed in the manufacturing of aero-engines. These alloys are difficult to machine, and tensile residual stresses are generated during machining. These tensile residual stresses can negatively affect the performance of aero-engine components. Nevertheless, residual stresses can vary due to thermal or mechanical loading. These variations must be considered to evaluate the real influence of residual stresses on component behavior. This paper studies the effect of thermal loads on machining-induced residual stresses in the alloy Inconel 718. A ring-shaped Inconel 718 part was face-turned, and specimens were extracted from it. Specimens were exposed at 550 and 650 °C for 10 min, 1 and 10 h. Residual stresses were measured, and microstructure was observed before and after thermal exposure. Residual stress variations found after thermal exposure were the consequence of two factors: relaxation of strain bands during the early stage of exposure and diffusion-controlled creep. In addition, a modified Zener-Wert-Avrami model is proposed to predict residual stress relaxation caused by the diffusion-controlled creep. Once having fitted the modified Zener-Wert-Avrami model, the study was extended for a wider range of temperatures (400-650 °C). This analysis showed that surface residual stresses do not relax significantly at temperatures below 500 °C.

  9. In situ Weak Magnetic-Assisted Thermal Stress Field Reduction Effect in Laser Welding

    Science.gov (United States)

    Liang, Lvjie; Pang, Shengyong; Shao, Xinyu; Wang, Chunming; Jiang, Ping; Chen, Xin

    2017-11-01

    For decades, post-welding magnetic treatment has been used to reduce residual stress of welds by improving the crystal structure of solid-state welds. In this paper, we propose a new magnetic treatment method, which can reduce the time-dependent thermal stress field in situ and reduce the final residual stress of welds by simply exerting an assisted weak magnetic field perpendicular to the welding direction and workpiece during laser welding. A new finite-element model is developed to understand the thermal-mechanical physical process of the magnetic-assisted laser welding. For the widely used 304 austenite stainless steel, we theoretically observed that this method can reduce around 10 pct of the time-dependent thermal stress field, and finally reduce approximately 20 MPa of residual stress near the heat-affected zone with a 415-mT magnetic field for typical welding process parameters. A new mechanism based on magneto-fluid dynamics is proposed to explain the theoretical predications by combining high-speed imaging experiments of the transient laser welding process. The developed method is very simple but surprisingly effective, which opens new avenues for thermal stress reduction in laser welding of metals, particularly heat-sensitive metallic materials.

  10. Environmental assessment of the potential effects of aquifer thermal energy storage systems on microorganisms in groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Hicks, R.J.; Stewart, D.L.

    1988-03-01

    The primary objective of this study was to evaluate the potential environmental effects (both adverse and beneficials) of aquifer thermal energy storage (ATES) technology pertaining to microbial communities indigenous to subsurface environments (i.e., aquifers) and the propagation, movement, and potential release of pathogenic microorganisms (specifically, Legionella) within ATES systems. Seasonal storage of thermal energy in aquifers shows great promise to reduce peak demand; reduce electric utility load problems; contribute to establishing favorable economics for district heating and cooling systems; and reduce pollution from extraction, refining, and combustion of fossil fuels. However, concerns that the widespread implementation of this technology may have adverse effects on biological systems indigeneous to aquifers, as well as help to propagate and release pathogenic organisms that enter thee environments need to be resolved. 101 refs., 2 tabs.

  11. Magnetic field and thermal radiation effects on steady hydromagnetic Couette flow through a porous channel

    Directory of Open Access Journals (Sweden)

    Chigozie Israel-Cookey

    2010-09-01

    Full Text Available This paper investigates effects of thermal radiation and magnetic field on hydromagnetic Couette flow of a highly viscous fluid with temperature-dependent viscosity and thermal conductivity at constant pressure through a porous channel. The influence of the channel permeability is also assessed. The relevant governing partial differential equations have been transformed to non-linear coupled ordinary differential equations by virtue of the steady nature of the flow and are solved numerically using a marching finite difference scheme to give approximate solutions for the velocity and temperature profiles. We highlight the effects of Nahme numbers, magnetic field, radiation and permeability parameters on both profiles. The results obtained are used to give graphical illustrations of the distribution of the flow variables and are discussed.

  12. On the Effective Thermal Conductivity of Porous Packed Beds with Uniform Spherical Particles

    Science.gov (United States)

    Kandula, Max

    2010-01-01

    Point contact models for the effective thermal conductivity of porous media with uniform spherical inclusions have been briefly reviewed. The model of Zehner and Schlunder (1970) has been further validated with recent experimental data over a broad range of conductivity ratio from 8 to 1200 and over a range of solids fraction up to about 0.8. The comparisons further confirm the validity of Zehner-Schlunder model, known to be applicable for conductivity ratios less than about 2000, above which area contact between the particles becomes significant. This validation of the Zehner-Schlunder model has implications for its use in the prediction of the effective thermal conductivity of water frost (with conductivity ratio around 100) which arises in many important areas of technology.

  13. Numerical investigation of a three-dimensional disc-pad model with and without thermal effects

    Directory of Open Access Journals (Sweden)

    Belhocine Ali

    2015-01-01

    Full Text Available This study aims to identify thermal effects in the structure and the contact behavior of a disc-pad assembly using a finite element approach. The first analysis is performed on the disc-pad model in the absence of thermal effects. The structural performance of the disc-pad model is predicted in terms of factors such as the deformation and Von Mises stress. Next, thermomechanical analysis is performed on the same disc-pad model with the inclusion of convection, adiabatic, and heat flux elements. The predicted temperature distribution, deformation, stress, and contact pressure are presented. The structural performance between the two analyses (mechanical and thermomechanical is compared. This study can assist brake engineers in choosing a suitable analysis method to critically evaluate the structural and contact behavior of the disc brake assembly.

  14. Estimation of the effective thermal conductivity of carbon felts used as PEMFC gas diffusion layers

    Energy Technology Data Exchange (ETDEWEB)

    Ramousse, Julien; Didierjean, Sophie; Lottin, Olivier; Maillet, Denis [Laboratoire d' Energetique et de Mecanique Theorique et Appliquee, UMR 7563 CNRS-INPL-UHP, 2, avenue de la foret de Haye, BP 160, 54504 Vandoeuvre les Nancy Cedex (France)

    2008-01-15

    Thermal conductivity of gas diffusion layers (GDL) used in fuel cells is a key parameter for the analysis of heat transfer in membrane electrodes assembly (MEA). In this paper, we focus on non-woven carbon felts. Although correlations are available, the felts thermal conductivity is difficult to estimate due to the nature of heat transfer in porous and fibrous materials: the effective conductivity of the solid phase is roughly known and the correlations giving effective conductivity of porous media (solid and fluid phases) have restricted range of application. Consequently, we chose to associate an analytical and an experimental approach. Their results converge and clearly show that the majority of values encountered in the literature are, most probably, highly overestimated. (author)

  15. Effect of Thermal Cycling on the Tensile Behavior of Polymer Composites Reinforced by Basalt and Carbon Fibers

    Science.gov (United States)

    Khalili, S. Mohammad Reza; Najafi, Moslem; Eslami-Farsani, Reza

    2017-01-01

    The aim of the present work was to investigate the effect of thermal cycling on the tensile behavior of three types of polymer-matrix composites — a phenolic resin reinforced with woven basalt fibers, woven carbon fibers, and hybrid basalt and carbon fibers — in an ambient environment. For this purpose, tensile tests were performed on specimens previously subjected to a certain number of thermal cycles. The ultimate tensile strength of the specimen reinforced with woven basalt fibers had by 5% after thermal cycling, but the strength of the specimen with woven carbon fibers had reduced to a value by 11% higher than that before thermal cycling.

  16. The thermal effect on the left-handedness of the mesoscopic composite right-Left handed transmission line

    Science.gov (United States)

    Wei, Xiao-Jing; Zhao, Shun-Cai; Guo, Hong-Wei

    2017-10-01

    Starting from the quantum fluctuation of current in the mesoscopic composite right-left handed transmission line (CRLH-TL) in the thermal Fock state, we investigate the left-handedness dependent of the frequencies, intensity and quantum fluctuations of the current field in the CRLH-TL under different thermal environment. The results show that the intensity and quantum fluctuations of current field in lower frequency bands affect the left-handedness distinctly under different thermal environment. The thermal effect on the left-handedness in the mesoscopic CRLH-TL deserves further experimental investigation in its miniaturization application.

  17. Effect of Set-point Variation on Thermal Comfort and Energy Use in a Plus-energy Dwelling

    DEFF Research Database (Denmark)

    Toftum, Jørn; Kazanci, Ongun Berk; Olesen, Bjarne W.

    2016-01-01

    -points, and control dead-bands have a direct effect on the thermal environment in and the energy use of a building. The thermal environment in and the energy use of a building are associated with the thermal mass of the building and the control strategy, including set-points and control dead-bands. With thermally...... active building systems (TABS), temperatures are allowed to drift within the comfort zone, while in spaces with air-conditioning, temperatures in a narrower interval typically are aimed at. This behavior of radiant systems provides certain advantages regarding energy use, since the temperatures...

  18. Effect of Rotation on Thermal Instability in Rivlin-Ericksen Elastico-Viscous Fluid

    Science.gov (United States)

    Sharma, R. C.; Kumar, P.

    1996-07-01

    The thermal instability of a layer of Rivlin-Ericksen elastico-viscous fluid acted on by a uniform rotation is considered. For stationary convection, a Rivlin-Ericksen elastico-viscous fluid behaves like a Newtonian fluid. It is found that rotation has a stabilizing effect and introduces oscillatory modes in the system. The visco-elasticity also introduces oscillatory modes in the system. A suffi-cient condition for the non-existence of overstability is also obtained.

  19. Effects of voids on thermal-mechanical reliability of lead-free solder joints

    Directory of Open Access Journals (Sweden)

    Benabou Lahouari

    2014-06-01

    Full Text Available Reliability of electronic packages has become a major issue, particularly in systems used in electrical or hybrid cars where severe operating conditions must be met. Many studies have shown that solder interconnects are critical elements since many failure mechanisms originate from their typical response under thermal cycles. In this study, effects of voids in solder interconnects on the electronic assembly lifetime are estimated based on finite element simulations.

  20. Effects of Environmental Enrichment on Thermal Sensitivity in an Operant Orofacial Pain Assay

    OpenAIRE

    Rossi, Heather L.; Neubert, John K.

    2007-01-01

    Environmental enrichment reduces reactivity to stressor and could also modulate pain perception. In this study we sought to compare the effects of enriched and standard housing on temperature perception. In an operant assay, rats housed in an enriched environment exhibited significantly lower sensitivities to thermal stimuli and displayed less exploratory behavior in a rearing chamber. These findings indicate that environmental enrichment can significantly affect temperature perception, likel...

  1. Thermographic registration of thermal effects in plants exposed to cold stress

    Directory of Open Access Journals (Sweden)

    Kovchavtcev A.P.

    2011-12-01

    Full Text Available In present paper the possibility of continuous measurement of thermal effects of plants by thermography was investigated. The problems of measurement precision decreasing and thermograph calibration to cold-restraint stress process temperature region was discussed. The possibility of fast temperature measurement of plants in cold-restraint stress process was investigated. The dead temperature region of winter wheat was find out.

  2. Effects of the Gram stain on microspheres from thermal polyamino acids.

    Science.gov (United States)

    FOX, S W; YUYAMA, S

    1963-02-01

    Fox, Sidney W. (The Florida State University, Tallahassee) and Shuhei Yuyama. Effects of the Gram stain on microspheres from thermal polyamino acids. J. Bacteriol. 85:279-283. 1963.-Microspheres produced from acid proteinoid accept the Gram stain. The stain is negative, but microspheres produced from mixtures containing a sufficient proportion of lysine proteinoid stain positive. Microspheres produced from mixtures containing the appropriate proportions contain individuals which stain positive and others which stain negative.

  3. EFFECTS OF THE GRAM STAIN ON MICROSPHERES FROM THERMAL POLYAMINO ACIDS1

    Science.gov (United States)

    Fox, Sidney W.; Yuyama, Shuhei

    1963-01-01

    Fox, Sidney W. (The Florida State University, Tallahassee) and Shuhei Yuyama. Effects of the Gram stain on microspheres from thermal polyamino acids. J. Bacteriol. 85:279–283. 1963.—Microspheres produced from acid proteinoid accept the Gram stain. The stain is negative, but microspheres produced from mixtures containing a sufficient proportion of lysine proteinoid stain positive. Microspheres produced from mixtures containing the appropriate proportions contain individuals which stain positive and others which stain negative. Images PMID:13959050

  4. Effects of Urban Configuration on Human Thermal Conditions in a Typical Tropical African Coastal City

    OpenAIRE

    Emmanuel Lubango Ndetto; Andreas Matzarakis

    2013-01-01

    A long-term simulation of urban climate was done using the easily available long-term meteorological data from a nearby synoptic station in a tropical coastal city of Dar es Salaam, Tanzania. The study aimed at determining the effects of buildings’ height and street orientations on human thermal conditions at pedestrian level. The urban configuration was represented by a typical urban street and a small urban park near the seaside. The simulations were conducted in the microscale applied clim...

  5. A facile strategy for the reduction of graphene oxide and its effect on thermal conductivity of epoxy based composites

    Directory of Open Access Journals (Sweden)

    F. Xie

    2016-06-01

    Full Text Available A facile and efficient approach to reduce graphene oxide with Al particles and potassium hydroxide was developed at moderate temperature and the graphene/epoxy composite was prepared by mould casting method. The as-prepared graphene has been confirmed by Transmission electron microscopy, Fourier transform infrared spectrometer, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Thermal gravimetric analysis. This provides a new green way to synthesize graphene with high surface area and opens another opportunity for the production of graphene. Effects of graphene on thermal conductivity, thermal stability and microstructures of the epoxy-based composite were also investigated. The results showed that thermal conductivity of the composite exhibited a remarkable improvement with increasing content of graphene and thermal conductivity could reach 1.192 W/(m*K when filled with 3 wt% graphene. Moreover, graphene/epoxy composite exhibits good thermal stability with 3 wt% graphene.

  6. Control of propagation characteristics of spin wave pulses via elastic and thermal effects

    Energy Technology Data Exchange (ETDEWEB)

    Gómez-Arista, Ivan [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, CU, 04510 D.F., México (Mexico); Kolokoltsev, O., E-mail: oleg.kolokoltsev@ccadet.unam.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, CU, 04510 D.F., México (Mexico); Acevedo, A.; Qureshi, N. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, CU, 04510 D.F., México (Mexico); Ordóñez-Romero, César L. [Instituto de Física, Universidad Nacional Autónoma de México, CU, 04510 D.F., México (Mexico)

    2017-05-01

    A study of the magnetoelastic (ME) and thermal effects governing the phase (φ) and amplitude of magnetostatic surface spin wave (MSSW) pulses propagating in Ga:YIG/GGG and permalloy magnonic waveguides is presented. The ME effects were studied in a flexural configuration, under punctual mechanical force (F). Thermally induced ME and demagnetization phenomena were controlled by optically injected thermal power P{sub th}. It was determined that in an unclamped Ga:YIG waveguide, the force F that induces the phase shift Δφ=π, decreases by a quadratic law in the range from 1 mN to nN, and the P{sub th} at which Δφ=π decreases linearly from mW to μW as the waveguide volume decreases from mm{sup 3} to nm{sup 3}. For nano-volume waveguides the ME control energy (E{sub me}) can be of order of aJ, and the thermal control energy (ΔE{sub th}) can be as small as 50 fJ. The response time of these effects lies in the ns time scale. Both the mechanical and the thermo-magnetic forces provide an effective control of MSSW pulse amplitude, in addition to its phase shift. The thermo-magnetic effect allows one to realize variable delays of a MSSW pulse. - Highlights: • The Magneto-elastic (ME) and optically induced thermal effects governing the phase and amplitude of magnetostatic surface spin wave (MSSW) pulses propagating in Ga:YIG/GGG and permalloy magnonic waveguides are presented. • A mechanical force that causes phase shift Δφ=π for spin waves in the waveguides decreases by a quadratic law in the range from 1 mN to nN, and the optical power that induces the phase shift Δφ=π, decreases linearly from mW to μW as the waveguide volume decreases from mm{sup 3} to nm{sup 3}. • The response time of these effects can lie in the ns time scale.

  7. Self-heating and memory effects in RF power amplifiers explained through electro-thermal

    DEFF Research Database (Denmark)

    Wei, Wei; Jensen, Ole Kiel; Mikkelsen, Jan H.

    2013-01-01

    Self-heating has already been proven to be one of the key sources to memory effects in RF power amplifiers (PAs). However, mechanisms behind the generation of memory effects, as caused by self-heating have not been well documented. On basis of transistor physical properties this paper proposes...... a simple electro-thermal model and shows how self-heating can generate different types of memory effects, such as bandwidth dependent intermodulation components and hysteresis loops. In addition, it is shown that self-heating can result in generation of new spectral components even in an otherwise linear...

  8. Effects of Starvation and Thermal Stress on the Thermal Tolerance of Silkworm, Bombyx mori: Existence of Trade-offs and Cross-Tolerances.

    Science.gov (United States)

    Mir, A H; Qamar, A

    2017-09-27

    Organisms, in nature, are often subjected to multiple stressors, both biotic and abiotic. Temperature and starvation are among the main stressors experienced by organisms in their developmental cycle and the responses to these stressors may share signaling pathways, which affects the way these responses are manifested. Temperature is a major factor governing the performance of ectothermic organisms in ecosystems worldwide and, therefore, the thermal tolerance is a central issue in the thermobiology of these organisms. Here, we investigated the effects of starvation as well as mild heat and cold shocks on the thermal tolerance of the larvae of silkworm, Bombyx mori (Linnaeus). Starvation acted as a meaningful or positive stressor as it improved cold tolerance, measured as chill coma recovery time (CCRT), but, at the same time, it acted as a negative stressor and impaired the heat tolerance, measured as heat knockdown time (HKT). In the case of heat tolerance, starvation negated the positive effects of both mild cold as well as mild heat shocks and thus indicated the existence of trade-off between these stressors. Both mild heat and cold shocks improved the thermal tolerance, but the effects were more prominent when the indices were measured in response to a stressor of same type, i.e., a mild cold shock improved the cold tolerance more than the heat tolerance and vice versa. This improvement in thermal tolerance by both mild heat as well as cold shocks indicated the possibility of cross-tolerance between these stressors.

  9. Thermal effects on the Raman phonon of few-layer phosphorene

    Directory of Open Access Journals (Sweden)

    Zhi-Peng Ling

    2015-12-01

    Full Text Available Two-dimensional phosphorene is a promising channel material for next generation transistor applications due to its superior carrier transport property. Here, we report the influence of thermal effects on the Raman phonon of few-layer phosphorene formed on hafnium-dioxide (HfO2 high-k dielectric. When annealed at elevated temperatures (up to 200 °C, the phosphorene film was found to exhibit a blue shift in both the out-of-plane (A1g and in-plane (B2g and A2g phonon modes as a result of compressive strain effect. This is attributed to the out-diffusion of hafnium (Hf atoms from the underlying HfO2 dielectric, which compresses the phosphorene in both the zigzag and armchair directions. With a further increase in thermal energy beyond 250 °C, strain relaxation within phosphorene eventually took place. When this happens, the phosphorene was unable to retain its intrinsic crystallinity prior to annealing, as evident from the broadening of full-width at half maximum of the Raman phonon. These results provide an important insight into the impact of thermal effects on the structural integrity of phosphorene when integrated with high-k gate dielectric.

  10. Thermal-Hydraulic Integral Effect Test with the ATLS for Investigation on CEDM Penetration Nozzle Integrity

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Kyoungho; Seokcho; Park, Hyunsik; Choi, Namhyun; Park, Yusun; Kim, Jongrok; Bae, Byounguhn; Kim, Yeonsik; Choi, Kiyong; Song, Chulhwa [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    In this study, thermal-hydraulic integral effect test with the ATLAS (Advanced Thermal-Hydraulic Test Loop for Accident Simulation) was performed for simulating a failure of CEDM penetration nozzle. The main objectives of the present test were not only to provide physical insight into the system response during a failure of CEDM penetration nozzle but also to establish an integral effect test database for the validation of the safety analysis codes. Furthermore, present experimental data were utilized to resolve the safety issue raised by the PWSCC at the CEDM penetration nozzle of the YGN-3. Thermal-hydraulic integral effect test with the ATLAS was performed for simulating a failure of CEDM penetration nozzle. Failure of two penetration nozzles of the CEDM in the APR1400 was simulated. Initial and boundary conditions were determined with respect to the reference conditions of the APR1400. However, with an aim of corresponding to the YGN-3 situation, the safety injection water was supplied via CLI mode. Compared to the cold leg break SBLOCA, the consequences of the event were milder in terms of a loop seal clearance, break flow rate, collapsed water level, and PCT. This could be mainly attributed to the small break flow rate in case of the failure in the RPV upper head. Present experimental data were utilized to resolve the safety issue raised by the PWSCC at the CEDM penetration nozzle of the YGN-3.

  11. The effect of landscape complexity and microclimate on the thermal tolerance of a pest insect.

    Science.gov (United States)

    Alford, Lucy; Tougeron, Kévin; Pierre, Jean-Sébastien; Burel, Françoise; van Baaren, Joan

    2017-03-21

    Landscape changes are known to exacerbate the impacts of climate change. As such, understanding the combined effect of climate and landscape on agroecosystems is vital if we are to maintain the function of agroecosystems. This study aimed to elucidate the effects of agricultural landscape complexity on the microclimate and thermal tolerance of an aphid pest to better understand how landscape and climate may interact to affect the thermal tolerance of pest species within the context of global climate change. Meteorological data were measured at the landscape level, and cereal aphids (Sitobion avenae, Metopolophium dirhodum and Rhopalosiphum padi) sampled, from contrasting landscapes (simple and complex) in winter 2013/2014 and spring 2014 in cereal fields of Brittany, France. Aphids were returned to the laboratory and the effect of landscape of origin on aphid cold tolerance (as determined by CTmin ) was investigated. Results revealed that local landscape complexity significantly affected microclimate, with simple homogenous landscapes being on average warmer, but with greater temperature variation. Landscape complexity was shown to impact aphid cold tolerance, with aphids from complex landscapes being more cold tolerant than those from simple landscapes in both winter and spring, but with differences among species. This study highlights that future changes to land use could have implications for the thermal tolerance and adaptability of insects. Furthermore, not all insect species respond in a similar way to microhabitat and microclimate, which could disrupt important predator-prey relationships and the ecosystem service they provide. © 2017 Institute of Zoology, Chinese Academy of Sciences.

  12. Fluid Pressure, Thermal and Chemical Effects in Conditioning Permeability and Triggered Seismicity in Enhanced Geothermal Systems

    Science.gov (United States)

    Elsworth, D.; Izadi, G.; Zheng, B.; Taron, J.

    2011-12-01

    The evolution of permeability, heat or diffusive transfer area and triggered seismicity are intimately linked in forced-circulation systems such as EGS, CCS and unconventional hydrocarbon reservoirs where conditions are pushed far-from-equilibrium. We explore this evolution subject to coupled THMC processes in a prototypical EGS reservoir. We accommodate the influence of early-time changes in effective stress, mid-time changes in thermal stresses and ultimately incorporate long-term changes due to chemical effects. We develop a micromechanical model to represent the failure process and apply this model to represent energy release from individual critically oriented fractures. The changing stress state is calculated from the pore pressure, thermal drawdown and chemical effects for a coupled THMC model with dual porosity. This model is applied to a doublet geometry to explore the spatial and temporal migration for permeability evolution, access to reactive surface area and the triggering of seismicity as stimulation then production proceeds. Seismic activity is initially concentrated around the near-wellbore injection region. It is earliest for closely spaced fractures in reservoir rocks where the thermal drawdown of stress is largest at early times and results in numerous low-magnitude events. These observations are used to define the evolution of spatial changes within the reservoir and their migration with production, dependent on the mobilization of relic fractures.

  13. Morphological Characterization and Effective Thermal Conductivity of Dual-Scale Reticulated Porous Structures

    Directory of Open Access Journals (Sweden)

    Simon Ackermann

    2014-10-01

    Full Text Available Reticulated porous ceramic (RPC made of ceria are promising structures used in solar thermochemical redox cycles for splitting CO2 and H2O. They feature dual-scale porosity with mm-size pores for effective radiative heat transfer during reduction and µm-size pores within its struts for enhanced kinetics during oxidation. In this work, the detailed 3D digital representation of the complex dual-scale RPC is obtained using synchrotron submicrometer tomography and X-ray microtomography. Total and open porosity, pore size distribution, mean pore diameter, and specific surface area are extracted from the computer tomography (CT scans. The 3D digital geometry is then applied in direct pore level simulations (DPLS of Fourier’s law within the solid and the fluid phases for the accurate determination of the effective thermal conductivity at each porosity scale and combined, and for fluid-to-solid thermal conductivity from 10−5 to 1. Results are compared to predictions by analytical models for structures with a wide range of porosities 0.09–0.9 in both the strut’s µm-scale and bulk’s mm-scale. The morphological properties and effective thermal conductivity determined in this work serve as an input to volume-averaged models for the design and optimization of solar chemical reactors.

  14. Morphological Characterization and Effective Thermal Conductivity of Dual-Scale Reticulated Porous Structures.

    Science.gov (United States)

    Ackermann, Simon; Scheffe, Jonathan R; Duss, Jonas; Steinfeld, Aldo

    2014-10-28

    Reticulated porous ceramic (RPC) made of ceria are promising structures used in solar thermochemical redox cycles for splitting CO₂ and H₂O. They feature dual-scale porosity with mm-size pores for effective radiative heat transfer during reduction and µm-size pores within its struts for enhanced kinetics during oxidation. In this work, the detailed 3D digital representation of the complex dual-scale RPC is obtained using synchrotron submicrometer tomography and X-ray microtomography. Total and open porosity, pore size distribution, mean pore diameter, and specific surface area are extracted from the computer tomography (CT) scans. The 3D digital geometry is then applied in direct pore level simulations (DPLS) of Fourier's law within the solid and the fluid phases for the accurate determination of the effective thermal conductivity at each porosity scale and combined, and for fluid-to-solid thermal conductivity from 10-5 to 1. Results are compared to predictions by analytical models for structures with a wide range of porosities 0.09-0.9 in both the strut's µm-scale and bulk's mm-scale. The morphological properties and effective thermal conductivity determined in this work serve as an input to volume-averaged models for the design and optimization of solar chemical reactors.

  15. Effects and interactions of gallic acid, eugenol and temperature on thermal inactivation of Salmonella spp. in ground chicken

    Science.gov (United States)

    The combined effects of heating temperature (55 to 65C), gallic acid (0 to 2.0%), and eugenol (0 to 2.0%) on thermal inactivation of Salmonella in ground chicken were assessed. Thermal death times were determined in bags submerged in a heated water bath maintained at various set temperatures, follo...

  16. Interaction effects of radiation and convection measured by a thermal manikin wearing protective clothing with different radiant properties

    NARCIS (Netherlands)

    Havenith, G.; Wang, X.; Candas, V.; Hartog, E. den; Griefahn, B.; Holmér, I.; Meinander, H.; Richards, M.

    2005-01-01

    As part of the EU funded research project THERMPROTECT ('Thermal properties of protective clothing and their use') this paper deals with manikin experiments on the effects of heat radiation at different wind speeds, considering aspects related to the reflectivity of the clothing. A heated thermal

  17. Effect of thermal cycling on martensitic transformation and mechanical strengthening of stainless steels – A phase-field study

    DEFF Research Database (Denmark)

    Yeddu, Hemantha Kumar; Shaw, Brian A.; Somers, Marcel A. J.

    2017-01-01

    A 3D elastoplastic phase-field model is used to study the effect of thermal cycling on martensitic transformationas well as on mechanical strengthening of both austenite and martensite in stainless steel. The results show that with an increasing number of thermal cycles, martensite becomes more...

  18. Effects of seasonal and climate variations on calves' thermal comfort and behaviour.

    Science.gov (United States)

    Tripon, Iulian; Cziszter, Ludovic Toma; Bura, Marian; Sossidou, Evangelia N

    2014-09-01

    The aim of this study was to measure the effect of season and climate variations on thermal comfort and behaviour of 6-month-old dairy calves housed in a semi-opened shelter to develop animal-based indicators for assessing animal thermal comfort. The ultimate purpose was to further exploit the use of those indicators to prevent thermal stress by providing appropriate care to the animals. Measurements were taken for winter and summer seasons. Results showed that season significantly influenced (P ≤ 0.01) the lying down behaviour of calves by reducing the time spent lying, from 679.9 min in winter to 554.1 min in summer. Moreover, season had a significant influence (P ≤ 0.01) on feeding behaviour. In detail, the total length of feeding periods was shorter in winter, 442.1 min in comparison to 543.5 min in summer. Time spent drinking increased significantly (P ≤ 0.001), from 11.9 min in winter to 26.9 min in summer. Furthermore, season had a significant influence (P ≤ 0.001) on self grooming behaviour which was 5.5 times longer in duration in winter than in summer (1,336 s vs 244 s). It was concluded that calves' thermal comfort is affected by seasonal and climate variations and that this can be assessed by measuring behaviour with animal-based indicators, such as lying down, resting, standing up, feeding, rumination, drinking and self grooming. The indicators developed may be a useful tool to prevent animal thermal stress by providing appropriate housing and handling to calves under seasonal and climate challenge.

  19. Effects of seasonal and climate variations on calves' thermal comfort and behaviour

    Science.gov (United States)

    Tripon, Iulian; Cziszter, Ludovic Toma; Bura, Marian; Sossidou, Evangelia N.

    2014-09-01

    The aim of this study was to measure the effect of season and climate variations on thermal comfort and behaviour of 6-month-old dairy calves housed in a semi-opened shelter to develop animal-based indicators for assessing animal thermal comfort. The ultimate purpose was to further exploit the use of those indicators to prevent thermal stress by providing appropriate care to the animals. Measurements were taken for winter and summer seasons. Results showed that season significantly influenced ( P ≤ 0.01) the lying down behaviour of calves by reducing the time spent lying, from 679.9 min in winter to 554.1 min in summer. Moreover, season had a significant influence ( P ≤ 0.01) on feeding behaviour. In detail, the total length of feeding periods was shorter in winter, 442.1 min in comparison to 543.5 min in summer. Time spent drinking increased significantly ( P ≤ 0.001), from 11.9 min in winter to 26.9 min in summer. Furthermore, season had a significant influence ( P ≤ 0.001) on self grooming behaviour which was 5.5 times longer in duration in winter than in summer (1,336 s vs 244 s). It was concluded that calves' thermal comfort is affected by seasonal and climate variations and that this can be assessed by measuring behaviour with animal-based indicators, such as lying down, resting, standing up, feeding, rumination, drinking and self grooming. The indicators developed may be a useful tool to prevent animal thermal stress by providing appropriate housing and handling to calves under seasonal and climate challenge.

  20. Thermal effect on magnetic parameters of high-coercivity cobalt ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Chagas, E. F., E-mail: efchagas@fisica.ufmt.br; Ponce, A. S.; Prado, R. J.; Silva, G. M. [Instituto de Física, Universidade Federal de Mato Grosso, 78060-900 Cuiabá-MT (Brazil); Bettini, J. [Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, 13083-970 Campinas (Brazil); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas, Rua Xavier Sigaud 150 Urca. Rio de Janeiro (Brazil)

    2014-07-21

    We prepared very high-coercivity cobalt ferrite nanoparticles synthesized by a combustion method and using short-time high-energy mechanical milling to increase strain and the structural defects density. The coercivity (H{sub C}) of the milled sample reached 3.75 kOe—a value almost five times higher than that obtained for the non-milled material (0.76 kOe). To investigate the effect of the temperature on the magnetic behavior of the milled sample, we performed a thermal treatment on the milled sample at 300, 400, and 600 °C for 30 and 180 min. We analyzed the changes in the magnetic behavior of the nanoparticles due to the thermal treatment using the hysteresis curves, Williamson-Hall analysis, and transmission electron microscopy. The thermal treatment at 600 °C causes decreases in the microstructural strain and density of structural defects resulting in a significant decrease in H{sub C}. Furthermore, this thermal treatment increases the size of the nanoparticles and, as a consequence, there is a substantial increase in the saturation magnetization (M{sub S}). The H{sub C} of the samples treated at 600 °C for 30 and 180 min were 2.24 and 1.93 kOe, respectively, and the M{sub S} of these same samples increased from 57 emu/g to 66 and 70 emu/g, respectively. The H{sub C} and the M{sub S} are less affected by the thermal treatment at 300 and 400 °C.

  1. SILLi 1.0: a 1-D numerical tool quantifying the thermal effects of sill intrusions

    Directory of Open Access Journals (Sweden)

    K. Iyer

    2018-01-01

    Full Text Available Igneous intrusions in sedimentary basins may have a profound effect on the thermal structure and physical properties of the hosting sedimentary rocks. These include mechanical effects such as deformation and uplift of sedimentary layers, generation of overpressure, mineral reactions and porosity evolution, and fracturing and vent formation following devolatilization reactions and the generation of CO2 and CH4. The gas generation and subsequent migration and venting may have contributed to several of the past climatic changes such as the end-Permian event and the Paleocene–Eocene Thermal Maximum. Additionally, the generation and expulsion of hydrocarbons and cracking of pre-existing oil reservoirs around a hot magmatic intrusion are of significant interest to the energy industry. In this paper, we present a user-friendly 1-D finite element method (FEM-based tool, SILLi, which calculates the thermal effects of sill intrusions on the enclosing sedimentary stratigraphy. The model is accompanied by three case studies of sills emplaced in two different sedimentary basins, the Karoo Basin in South Africa and the Vøring Basin off the shore of Norway. An additional example includes emplacement of a dyke in a cooling pluton which forgoes sedimentation within a basin. Input data for the model are the present-day well log or sedimentary column with an Excel input file and include rock parameters such as thermal conductivity, total organic carbon (TOC content, porosity and latent heats. The model accounts for sedimentation and burial based on a rate calculated by the sedimentary layer thickness and age. Erosion of the sedimentary column is also included to account for realistic basin evolution. Multiple sills can be emplaced within the system with varying ages. The emplacement of a sill occurs instantaneously. The model can be applied to volcanic sedimentary basins occurring globally. The model output includes the thermal evolution of the sedimentary

  2. SILLi 1.0: a 1-D numerical tool quantifying the thermal effects of sill intrusions

    Science.gov (United States)

    Iyer, Karthik; Svensen, Henrik; Schmid, Daniel W.

    2018-01-01

    Igneous intrusions in sedimentary basins may have a profound effect on the thermal structure and physical properties of the hosting sedimentary rocks. These include mechanical effects such as deformation and uplift of sedimentary layers, generation of overpressure, mineral reactions and porosity evolution, and fracturing and vent formation following devolatilization reactions and the generation of CO2 and CH4. The gas generation and subsequent migration and venting may have contributed to several of the past climatic changes such as the end-Permian event and the Paleocene-Eocene Thermal Maximum. Additionally, the generation and expulsion of hydrocarbons and cracking of pre-existing oil reservoirs around a hot magmatic intrusion are of significant interest to the energy industry. In this paper, we present a user-friendly 1-D finite element method (FEM)-based tool, SILLi, which calculates the thermal effects of sill intrusions on the enclosing sedimentary stratigraphy. The model is accompanied by three case studies of sills emplaced in two different sedimentary basins, the Karoo Basin in South Africa and the Vøring Basin off the shore of Norway. An additional example includes emplacement of a dyke in a cooling pluton which forgoes sedimentation within a basin. Input data for the model are the present-day well log or sedimentary column with an Excel input file and include rock parameters such as thermal conductivity, total organic carbon (TOC) content, porosity and latent heats. The model accounts for sedimentation and burial based on a rate calculated by the sedimentary layer thickness and age. Erosion of the sedimentary column is also included to account for realistic basin evolution. Multiple sills can be emplaced within the system with varying ages. The emplacement of a sill occurs instantaneously. The model can be applied to volcanic sedimentary basins occurring globally. The model output includes the thermal evolution of the sedimentary column through time and

  3. Boride ceramics covalent functionalization and its effect on the thermal conductivity of epoxy composites

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Zhi-Qiang, E-mail: yuzhiqiang@fudan.edu.cn [Department of Materials Science, Fudan University, 200433 Shanghai (China); Wu, Yicheng [Department of Materials Science, Fudan University, 200433 Shanghai (China); Wei, Bin; Baier, Horst [Institute of Lightweight Structures, Technical University Munich (TUM), Boltzmannstr. 15, D-85747 Garching (Germany)

    2015-08-15

    Zirconium diboride/aluminium oxide (ZrB{sub 2}/Al{sub 2}O{sub 3}) composite particles were functionalized with epoxide functionalized γ-glycidoxypropyltrimethoxysilane by the covalent bonding approach to improve the interfacial compatibility of composite particles in epoxy matrix. The composites of epoxy resin filled with functionalized ZrB{sub 2}/Al{sub 2}O{sub 3} were prepared by in situ bulk condensation polymerization of bisphenol A and epichlorohydrin in the presence of ZrB{sub 2}/Al{sub 2}O{sub 3}. The heat-conducting properties of composites were investigated by the finite element method (FEM) and the thermal conductivity test. The finite-element program ANSYS was used for this numerical analysis, and three-dimensional spheres-in-cube lattice array models were built to simulate the microstructure of composite materials for different filler contents. The thermal conductivity of composites was determined by laser flash method (LFA447 Nanoflash), using the measured heat capacity and thermal diffusivity, with separately entered density data. The results show that the effective chemical bonds are formed between ZrB{sub 2}/Al{sub 2}O{sub 3} and γ-glycidoxypropyltrimethoxysilane after the surface functionalization. The interfacial compatibility and bonding of modified particles with the epoxy matrix are improved. The thermal conductivities of functionalized composites with 3 vol% and 5 vol% loading are increased by 8.3% and 12.5% relative to the unmodified composites, respectively. Comparison of experimental values and calculated values of the thermal conductivity, the average relative differences are under 5%. The predictive values of thermal conductivity of epoxy composites are in reasonable agreement with the experimental values. - Highlights: • The surfaces of ZrB{sub 2}/Al{sub 2}O{sub 3} were functionalized by silane coupling agents. • The thermal conductivity (TC) of modified epoxy composites is improved significantly. • The FEM values of TC are in

  4. Estimation of effective thermal conductivity enhancement using foam in heat exchangers based on a new analytical model

    Directory of Open Access Journals (Sweden)

    Maryam Haghighi

    2010-03-01

    Full Text Available Thermal performance of open-cell metal foam has been investigated under low Reynolds number by comparing the heat transfer coefficient and thermal conductivity for the flow through a packed channel of high porosity metal foam to that of an open channel. In the case of Al-Air at porosity 0.971, the ratio of heat transfer coefficients is estimated to be 18.5 when the thermal conductivity ratio of foam matrix to fluid conductivity is 130. This demonstrates that the useusing of foam in the structure of conventional air coolers increases effective thermal conductivity, heat transfer coefficient and thermal performance considerably. To overcome the drawbacks of previous models, a new model to describe the effective thermal conductivity of foam was developed. The model estimates effective thermal conductivity based on a non-isotropic tetrakaidecahedron unit-cell and is not confined only to isotropic cases as in previous models. Effective thermal conductivity is a function of foam geometrical characteristics, including ligament length (L, length of the sides of horizontal square faces (b, inclination angle that defines the orientation of the hexagonal faces with respect to the rise direction (θ, porosity, size, shape of metal lump at ligament intersections and heat transfer direction. Changing dimensionless foam ligament radius or height (d from 0.1655 to 0.2126 for Reticulated vitreous foam -air (RVC-aAir at θ=π/4 and dimensionless spherical node diameter (e equal to 0.339, raises effective thermal conductivity by 31%. Moreover, increasing θ from π/4 to 0.4π for RVC-aAir at d=0.1655 and e=0.339 enhances effective thermal conductivity by 33%.

  5. Effects of acepromazine, butorphanol and buprenorphine on thermal and mechanical nociceptive thresholds in horses.

    Science.gov (United States)

    Love, E J; Taylor, P M; Murrell, J; Whay, H R

    2012-03-01

    To investigate the antinociceptive effects of buprenorphine administered in combination with acepromazine in horses and to establish an effective dose for use in a clinical environment. To evaluate the responses to thermal and mechanical stimulation following administration of 3 doses of buprenorphine compared to positive (butorphanol) and negative (glucose) controls. Observer blinded, randomised, crossover design using 6 Thoroughbred geldings (3-10 years, 500-560 kg). Thermal and mechanical nociceptive thresholds were measured 3 times at 15 min intervals. Horses then received acepromazine 0.05 mg/kg bwt with one of 5 treatments i.v.: 5% glucose (Glu), butorphanol 100 µg/kg bwt (But) buprenorphine 5 µg/kg bwt (Bup5), buprenorphine 7.5 µg/kg bwt (Bup7.5) and buprenorphine 10 µg/kg bwt (Bup10). Thresholds were measured 15, 30, 45, 60, 90, 120, 150, 180, 230 min, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 24 h post treatment administration. The 95% confidence intervals for threshold temperature (ΔT) for each horse were calculated and an antinociceptive effect defined as ΔT, which was higher than the upper limit of the confidence interval. Duration of thermal antinociception was analysed using a within-subjects ANOVA and peak mechanical thresholds with a general linear model with post hoc Tukey tests. Significance was set at Pbuprenorphine produced antinociception to a thermal stimulus for significantly longer than acepromazine and either butorphanol or glucose. This study suggests that buprenorphine has considerable potential as an analgesic in horses and should be examined further under clinical conditions and by investigation of the pharmacokinetic/pharmacodynamic profile. © 2011 EVJ Ltd.

  6. Effect of fish collagen modification on its thermal and rheological properties.

    Science.gov (United States)

    Safandowska, Marta; Pietrucha, Krystyna

    2013-02-01

    This report describes the effects of different methods of silver carp collagen crosslinking on its properties, particularly their thermal, mechanical viscoelastic and biological behavior. Enzymatic analyses and determination of the degree of crosslinking showed the stabilizing effect of both dehydrothermal (DHT) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)/N-hydroxysuccinimide (NHS) treatments on fish collagen. The results of the thermal (DSC) measurements demonstrated that collagen crosslinked by EDC/NHS ensured a high thermal stability compared with collagen crosslinked dehydrothermally. The denaturation temperature (T(d)) of unmodified collagen samples increased from 77 to 80°C and 88°C for DHT- and EDC/NHS-treated collagen, respectively. The influence of DHT or EDC/NHS crosslinking on the viscoelastic behavior of fish collagen was elaborated by a shift of the tan δ(max) peak toward higher temperatures resulting in higher thermostability of the modified collagen samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Can we use thermal imaging to evaluate the effects of carpal tunnel syndrome surgical decompression?

    Science.gov (United States)

    Baic, Agnieszka; Kasprzyk, Teresa; Rżany, Michał; Stanek, Agata; Sieroń, Karolina; Suszyński, Krzysztof; Marcol, Wiesław; Cholewka, Armand

    2017-01-01

    Abstract Research is intended to verify if thermal imaging can be used in diagnosing and monitoring the carpal tunnel syndrome (CTS). This disease is not easy to diagnose using traditional methods. Also, the difficulties in monitoring carpal tunnel surgery effects necessitate new, noninvasive method, which gives more information. The research group consists of 15 patients with CTS and control group of healthy people. All patients who were examined before surgery were also tested 4 weeks after surgery, to check the effects of treatment. In addition a lot of our patients had or will have open carpel tunnel release surgery. Diagnosis of CTS was performed by thermal imaging in both hands from phalanges to the area of the wrist on the external and palmar side of the palm. Using infrared (IR) camera one can observe high temperature gradient on hand-tested areas and these differences prove the diagnosis. Moreover patients after surgery have better temperature distribution and it was closer to control group. Results prove that surgery is the best, and currently, the only method to treat CTS. Thermal imaging may be helpful in diagnosing CTS. PMID:28953619

  8. Laser radiation induced thermal effects on the interactions between the tangential airflow and aluminum alloy

    Science.gov (United States)

    Lai, Shengying; Han, Bing; Ni, Xiaowu; Shen, Zhonghua; Lu, Jian

    2017-05-01

    The laser radiation induced thermal effects on the interactions between the tangential airflow and aluminum alloy are investigated numerically in this paper. A two dimensional model is developed for analysis of the evolutions of the temperature, stress and displacement of the flow and the aluminum alloy sheet at different flow speed through finite element method (FEM). It is found that in order to reach the same temperature in the aluminum alloy sheet, the input laser fluence needs to increase 4W/cm2 approximately, while the airflow speed increases one meter per second. Furthermore, in the situation of a thin aluminum alloy sheet irradiated by a large laser spot, the laser-induced thermal stress plays a leading role in the rupture of the sheet below the melting temperature. The airflow-induced shear stress and the pressure difference between the front and the rear surfaces of the sheet are minor effects compared to the thermal stress mentioned above. In addition, the bulge of the sheet induced by the laser heating would interact with the tangential airflow and lead to the formation of the downwind vortices, which may lead to a stronger shear stress. A vortex-induced oscillation appears when the Reynolds number of the airflow changes caused by the increase of the bulge height. And this vortex-induced oscillation would contribute to the damage of the aluminum sheet.

  9. Investigating the thermal environment effects on geometrically nonlinear vibration of smart functionally graded plates

    Energy Technology Data Exchange (ETDEWEB)

    Ebrahimi, Farzad; Rastgoo, Abbas; Bahrami, Mansoor Nikkhah [University of Tehran, Tehran (Iran, Islamic Republic of)

    2010-03-15

    An analytical solution for a sandwich circular FGM plate coupled with piezoelectric layers under one-dimensional heat conduction is presented. All materials of the device may be of any functional gradients in the direction of thickness. The solution exactly satisfies all the equilibrium conditions and continuity conditions for the stress, displacement and electric displacement as well as electric potential on the interfaces between adjacency layers. A nonlinear static problem is solved first to determine the initial stress state and pre-vibration deformations of the FG plate that is subjected to in-plane forces and applied actuator voltage in thermal environment in the case of simply supported boundary conditions. By adding an incremental dynamic state to the pre-vibration state, the differential equations that govern the nonlinear vibration behavior of pre-stressed piezoelectric coupled FGM plates are derived. The role of thermal environment as well as control effects on nonlinear static deflections and natural frequencies imposed by the piezoelectric actuators using high input voltages are investigated. Numerical examples are provided and simulation results are discussed. Numerical results for FGM plates with a mixture of metal and ceramic are presented in dimensionless forms. The good agreement between the results of this paper and those of the finite element (FE) analyses validated the presented approach. In a parametric study the emphasis is placed on investigating the effect of varying the applied actuator voltage and thermal environment as well as gradient index of FG plate on the dynamics and control characteristics of the structure

  10. Study on effectiveness of continuous solar dryer integrated with desiccant thermal storage for drying cocoa beans

    Directory of Open Access Journals (Sweden)

    Sari Farah Dina

    2015-03-01

    Full Text Available The main objective is to assess effectiveness of continuous solar dryer integrated with desiccant thermal storage for drying cocoa beans. Two type of desiccants were tested, molecular sieve 13× (Na86 [(AlO286·(SiO2106]·264H2O as an adsorbent type and CaCl2 as an absorbent type. The results revealed that during sunshine hours, the maximum temperature within the drying chamber varied from 40 °C to 54 °C. In average, it was 9–12 °C higher than ambient temperature. These temperatures are very suitable for drying cocoa beans. During off-sunshine hours, humidity of air inside the drying chamber was lower than ambient because of the desiccant thermal storage. Drying times for intermittent directs sun drying, solar dryer integrated with adsorbent, and solar dryer integrated with absorbent were 55 h, 41 h, and 30 h, respectively. Specific energy consumptions for direct sun drying, solar dryer integrated with adsorbent, and solar dryer integrated with absorber were 60.4 MJ/kg moist, 18.94 MJ/kg moist, and 13.29 MJ/kg moist, respectively. The main conclusion can be drawn here is that a solar dryer integrated with desiccant thermal storage makes drying using solar energy more effective in term of drying time and specific energy consumption.

  11. Numerical studies using FDM for viscous dissipation and thermal radiation effects...

    Directory of Open Access Journals (Sweden)

    Dr. Ali Eid

    2016-01-01

    Full Text Available The aim of the present paper is to study a numerical solution for the slip flow and heat transfer of a Newtonian fluid due to an impermeable stretching sheet which embedded in a porous medium with a power law surface velocity and variable thickness in the presence of thermal radiation, viscous dissipation and slip velocity effects. The flow is caused by a non-linear stretching of a sheet. Thermal conductivity of the fluid is assumed to vary linearly with temperature. The governing PDEs are transformed into a set of coupled non-linear ODEs which are using appropriate boundary conditions for various physical parameters. The remaining set of ODEs is solved numerically using finite difference method (FDM. The effects of the porous parameter, the wall thickness parameter, the radiation parameter, the Eckert number, the slip velocity parameter, the thermal conductivity parameter and the Prandtl number on the flow and temperature profiles are presented. Moreover, the local skin-friction and Nusselt numbers are presented. Comparison of obtained numerical results is made with previously published results in some special cases, and excellent agreement is noted. The results attained in this paper confirm the idea that FDM is powerful mathematical tool and it can be applied to a large class of linear and nonlinear problems arising in different fields of science and engineering.

  12. Effects of crowding on the thermal stability of heterogeneous protein solutions.

    Science.gov (United States)

    Despa, Florin; Orgill, Dennis P; Lee, Raphael C

    2005-08-01

    Crowding can substantially affect the transition of a protein between its native (N) and unfolded (U) states via volume exclusion effects. Also, it influences considerably the aggregation (A) of unfolded proteins. To examine the details, we developed an approach for computing the kinetic rates of the process N U --> A in which the concentration of the protein is explicitly taken into account. We then compute the relative change with temperature of the protein denaturation for various fractional volume occupancies and partition of proteins in solution. The analysis indicates that, in protein solutions in which the average distance between proteins is comparable with the radius of gyration of an unfolded protein, steric effects increase the stability of the proteins which are in compact, native states. In heterogeneous protein solutions containing various types of proteins with different thermal stabilities, the unfolding of the most thermolabile proteins will increase the stability of the other proteins. The results shed light on the way proteins change the thermal stability of a cell as they unfold and aggregate. This study may be valuable in questions related to the dynamics of thermal injuries.

  13. Permanent water swelling effect in low temperature thermally reduced graphene oxide

    Science.gov (United States)

    Papamatthaiou, S.; Argyropoulos, D.-P.; Masurkar, A.; Cavallari, M. R.; Farmakis, F.; Kymissis, I.; Georgoulas, N.

    2017-06-01

    We demonstrate permanent water trapping in reduced graphene oxide after high relative humidity exposure. For this purpose, we grew graphene oxide films via spin-coating on glass substrates followed by thermal reduction. The electrical resistance of the planar device was then measured. We observed that resistance is significantly increased after water vapor exposure and remains stable even after 250 days in ambient conditions. Various techniques were applied to desorb the water and decrease (recover) the material's resistance, but it was achieved only with low temperature thermal annealing (180 °C) under forming gas (H2/N2 mixture). The permanent effect of water absorption was also detected by x-ray photoelectron spectroscopy.

  14. Measure the effects of thermal discomfort on the performance of office work

    DEFF Research Database (Denmark)

    Lan, L.; Wargocki, P.; Lian, Z.W.

    2011-01-01

    Accuracy and speed are the two distinct aspects of human performance. A method was proposed by which the speed and accuracy were integrated into one measure by designing the tasks in such a way that the participants can only proceed to the next test when the task was performed without errors....... The method was examined through a subjective experiment with thermal environment as the prototypical example. The experimental results indicate that the negative effects of thermal discomfort on human performance were evaluated well by the tasks designed with the proposed method. It provides a useful tool...... for better measurement of human performance and helps to facilitate the development of quantitative relationship between IEQ and productivity....

  15. Effect of Different Photovoltaic Materials on Energetic and Exergetic Performance of Photovoltaic Thermal Arrays

    Directory of Open Access Journals (Sweden)

    Rajoria C.S.

    2017-01-01

    Full Text Available The study presents the effect of packing factor of Photovoltaic (PV module on the room temperature, cell temperature and efficiency of a proposed Building Integrated Semi-transparent Photovoltaic Thermal (BiSPVT and Building Integrated Opaque Photovoltaic Thermal (BiOPVT systems with duct mounted on the roof of the building. Different PV materials like mono-crystalline silicon (m-Si, amorphous silicon (a-Si, poly-crystalline silicon (p-Si, cadmium telluride (CdTe, copper indium selenide (CIS and hetero-junction with intrinsic thin layer (HIT have been considered in the analysis under the cold climatic condition of India. Since Srinagar (India has the cold climatic condition, therefore, its climatic data has been considered in the present analysis.

  16. RESOLUTION STRATEGY FOR GEOMECHANICALLY-RELATED REPOSITORY DESIGN FOR THERMAL-MECHANICAL EFFECTS (RDTME)

    Energy Technology Data Exchange (ETDEWEB)

    M. Board

    2003-04-01

    In September of 2000, the U.S. Nuclear Regulatory Commission (NRC) issued an Issue Resolution Status Report (NRC 2000). The Key Technical Issue (KTI) agreements on Repository Design and Thermal-Mechanical Effects (RDTME) were jointly developed at the Technical Exchange and Management Meeting held on February 6-8, 2001 in Las Vegas, Nevada. In that report, a number of geomechanically-related issues were raised regarding the determination of rock properties, the estimation of the impacts of geologic variability, the use of numerical models, and the examination of drift degradation and design approach to the ground support system for the emplacement drifts. Ultimately, the primary end products of the KTI agreement resolution processes are an assessment of the preclosure stability of emplacement drifts and the associated ground support requirements. There is also an assessment of the postclosure degradation of the excavations when subjected to thermal and seismic-related stresses as well as in situ loading over time.

  17. Effects study on the thermal stresses in a LEU metal foil annular target.

    Science.gov (United States)

    Govindarajan, Srisharan G; Solbrekken, Gary L

    2015-09-01

    The effects of fission gas pressure, uranium swelling and thermal contact conductance on the thermal-mechanical behavior of an annular target containing a low-enriched uranium foil (LEU) encapsulated in a nickel foil have been presented in this paper. The draw-plug assembly method is simulated to obtain the residual stresses, which are applied to the irradiation model as initial inputs, and the integrated assembly-irradiation process is simulated as an axisymmetric problem using the commercial finite element code Abaqus FEA. Parametric studies were performed on the LEU heat generation rate and the results indicate satisfactory irradiation performance of the annular target. The temperature and stress margins have been provided along with a discussion of the results. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Mori-Tanaka Based Estimates of Effective Thermal Conductivity of Various Engineering Materials

    Directory of Open Access Journals (Sweden)

    Michal Šejnoha

    2011-04-01

    Full Text Available The purpose of this paper is to present a simple micromechanics-based model to estimate the effective thermal conductivity of macroscopically isotropic materials of matrix-inclusion type. The methodology is based on the well-established Mori-Tanaka method for composite media reinforced with ellipsoidal inclusions, extended to account for imperfect thermal contact at the matrix-inclusion interface, random orientation of particles and particle size distribution. Using simple ensemble averaging arguments, we show that the Mori-Tanaka relations are still applicable for these complex systems, provided that the inclusion conductivity is appropriately modified. Such conclusion is supported by the verification of the model against a detailed finite-element study as well as its validation against experimental data for a wide range of engineering material systems.

  19. Effects of thermal fluctuations on non-minimal regular magnetic black hole

    Science.gov (United States)

    Jawad, Abdul; Shahzad, M. Umair

    2017-05-01

    We analyze the effects of thermal fluctuations on a regular black hole (RBH) of the non-minimal Einstein-Yang-Mill theory with gauge field of magnetic Wu-Yang type and a cosmological constant. We consider the logarithmic corrected entropy in order to analyze the thermal fluctuations corresponding to non-minimal RBH thermodynamics. In this scenario, we develop various important thermodynamical quantities, such as entropy, pressure, specific heats, Gibb's free energy and Helmholtz free energy. We investigate the first law of thermodynamics in the presence of logarithmic corrected entropy and non-minimal RBH. We also discuss the stability of this RBH using various frameworks such as the γ factor (the ratio of heat capacities), phase transition, grand canonical ensemble and canonical ensemble. It is observed that the non-minimal RBH becomes globally and locally more stable if we increase the value of the cosmological constant.

  20. Effects of thermal fluctuations on non-minimal regular magnetic black hole

    Energy Technology Data Exchange (ETDEWEB)

    Jawad, Abdul [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan); Shahzad, M.U. [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan); University of Central Punjab, CAMS, UCP Business School, Lahore (Pakistan)

    2017-05-15

    We analyze the effects of thermal fluctuations on a regular black hole (RBH) of the non-minimal Einstein-Yang-Mill theory with gauge field of magnetic Wu-Yang type and a cosmological constant. We consider the logarithmic corrected entropy in order to analyze the thermal fluctuations corresponding to non-minimal RBH thermodynamics. In this scenario, we develop various important thermodynamical quantities, such as entropy, pressure, specific heats, Gibb's free energy and Helmholtz free energy. We investigate the first law of thermodynamics in the presence of logarithmic corrected entropy and non-minimal RBH. We also discuss the stability of this RBH using various frameworks such as the γ factor (the ratio of heat capacities), phase transition, grand canonical ensemble and canonical ensemble. It is observed that the non-minimal RBH becomes globally and locally more stable if we increase the value of the cosmological constant. (orig.)