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Sample records for high average heat

  1. Investigation of laser diode face-pumped high average power heat capacity laser

    Institute of Scientific and Technical Information of China (English)

    Shenjin Zhang; Shouhuan Zhou; Xiaojun Tang; Guojiang Bi; Huachang LV

    2006-01-01

    The three-dimensional (3D) pump intensity distribution in medium of the laser diode (LD) pumped highaverage power heat capacity laser is simulated by the ray tracing method, and the divergence characteristicsof fast axis and slow axis of LD are simultaneously considered. The transient 3D temperature and stressdistributions are also simulated by the finite element method (FEM) with considering the uneven heatsource distribution in medium. A LD face-pumped Nd:GGG heat capacity laser is designed. The averageoutput power is 1.49 kW with an optical-optical efficiency of 24.1%.

  2. High average power supercontinuum sources

    Indian Academy of Sciences (India)

    J C Travers

    2010-11-01

    The physical mechanisms and basic experimental techniques for the creation of high average spectral power supercontinuum sources is briefly reviewed. We focus on the use of high-power ytterbium-doped fibre lasers as pump sources, and the use of highly nonlinear photonic crystal fibres as the nonlinear medium. The most common experimental arrangements are described, including both continuous wave fibre laser systems with over 100 W pump power, and picosecond mode-locked, master oscillator power fibre amplifier systems, with over 10 kW peak pump power. These systems can produce broadband supercontinua with over 50 and 1 mW/nm average spectral power, respectively. Techniques for numerical modelling of the supercontinuum sources are presented and used to illustrate some supercontinuum dynamics. Some recent experimental results are presented.

  3. High-Average Power Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, David H.; /SLAC; Power, John G.; /Argonne

    2012-09-05

    There has been significant progress in the development of high-power facilities in recent years yet major challenges remain. The task of WG4 was to identify which facilities were capable of addressing the outstanding R&D issues presently preventing high-power operation. To this end, information from each of the facilities represented at the workshop was tabulated and the results are presented herein. A brief description of the major challenges is given, but the detailed elaboration can be found in the other three working group summaries.

  4. High Average Power Yb:YAG Laser

    Energy Technology Data Exchange (ETDEWEB)

    Zapata, L E; Beach, R J; Payne, S A

    2001-05-23

    We are working on a composite thin-disk laser design that can be scaled as a source of high brightness laser power for tactical engagement and other high average power applications. The key component is a diffusion-bonded composite comprising a thin gain-medium and thicker cladding that is strikingly robust and resolves prior difficulties with high average power pumping/cooling and the rejection of amplified spontaneous emission (ASE). In contrast to high power rods or slabs, the one-dimensional nature of the cooling geometry and the edge-pump geometry scale gracefully to very high average power. The crucial design ideas have been verified experimentally. Progress this last year included: extraction with high beam quality using a telescopic resonator, a heterogeneous thin film coating prescription that meets the unusual requirements demanded by this laser architecture, thermal management with our first generation cooler. Progress was also made in design of a second-generation laser.

  5. High Average Power Optical FEL Amplifiers

    CERN Document Server

    Ben-Zvi, I; Litvinenko, V

    2005-01-01

    Historically, the first demonstration of the FEL was in an amplifier configuration at Stanford University. There were other notable instances of amplifying a seed laser, such as the LLNL amplifier and the BNL ATF High-Gain Harmonic Generation FEL. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance a 100 kW average power FEL. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting energy recovery linacs combine well with the high-gain FEL amplifier to produce unprecedented average power FELs with some advantages. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Li...

  6. High average-power induction linacs

    Energy Technology Data Exchange (ETDEWEB)

    Prono, D.S.; Barrett, D.; Bowles, E.; Caporaso, G.J.; Chen, Yu-Jiuan; Clark, J.C.; Coffield, F.; Newton, M.A.; Nexsen, W.; Ravenscroft, D.

    1989-03-15

    Induction linear accelerators (LIAs) are inherently capable of accelerating several thousand amperes of /approximately/ 50-ns duration pulses to > 100 MeV. In this paper we report progress and status in the areas of duty factor and stray power management. These technologies are vital if LIAs are to attain high average power operation. 13 figs.

  7. Materials for high average power lasers

    Energy Technology Data Exchange (ETDEWEB)

    Marion, J.E.; Pertica, A.J.

    1989-01-01

    Unique materials properties requirements for solid state high average power (HAP) lasers dictate a materials development research program. A review of the desirable laser, optical and thermo-mechanical properties for HAP lasers precedes an assessment of the development status for crystalline and glass hosts optimized for HAP lasers. 24 refs., 7 figs., 1 tab.

  8. MACHINE PROTECTION FOR HIGH AVERAGE CURRENT LINACS

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Kevin; Allison, Trent; Evans, Richard; Coleman, James; Grippo, Albert

    2003-05-01

    A fully integrated Machine Protection System (MPS) is critical to efficient commissioning and safe operation of all high current accelerators. The Jefferson Lab FEL [1,2] has multiple electron beam paths and many different types of diagnostic insertion devices. The MPS [3] needs to monitor both the status of these devices and the magnet settings which define the beam path. The matrix of these devices and beam paths are programmed into gate arrays, the output of the matrix is an allowable maximum average power limit. This power limit is enforced by the drive laser for the photocathode gun. The Beam Loss Monitors (BLMs), RF status, and laser safety system status are also inputs to the control matrix. There are 8 Machine Modes (electron path) and 8 Beam Modes (average power limits) that define the safe operating limits for the FEL. Combinations outside of this matrix are unsafe and the beam is inhibited. The power limits range from no beam to 2 megawatts of electron beam power.

  9. Industrial Applications of High Average Power FELS

    CERN Document Server

    Shinn, Michelle D

    2005-01-01

    The use of lasers for material processing continues to expand, and the annual sales of such lasers exceeds $1 B (US). Large scale (many m2) processing of materials require the economical production of laser powers of the tens of kilowatts, and therefore are not yet commercial processes, although they have been demonstrated. The development of FELs based on superconducting RF (SRF) linac technology provides a scaleable path to laser outputs above 50 kW in the IR, rendering these applications economically viable, since the cost/photon drops as the output power increases. This approach also enables high average power ~ 1 kW output in the UV spectrum. Such FELs will provide quasi-cw (PRFs in the tens of MHz), of ultrafast (pulsewidth ~ 1 ps) output with very high beam quality. This talk will provide an overview of applications tests by our facility's users such as pulsed laser deposition, laser ablation, and laser surface modification, as well as present plans that will be tested with our upgraded FELs. These upg...

  10. 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.

  11. Potential of high-average-power solid state lasers

    Energy Technology Data Exchange (ETDEWEB)

    Emmett, J.L.; Krupke, W.F.; Sooy, W.R.

    1984-09-25

    We discuss the possibility of extending solid state laser technology to high average power and of improving the efficiency of such lasers sufficiently to make them reasonable candidates for a number of demanding applications. A variety of new design concepts, materials, and techniques have emerged over the past decade that, collectively, suggest that the traditional technical limitations on power (a few hundred watts or less) and efficiency (less than 1%) can be removed. The core idea is configuring the laser medium in relatively thin, large-area plates, rather than using the traditional low-aspect-ratio rods or blocks. This presents a large surface area for cooling, and assures that deposited heat is relatively close to a cooled surface. It also minimizes the laser volume distorted by edge effects. The feasibility of such configurations is supported by recent developments in materials, fabrication processes, and optical pumps. Two types of lasers can, in principle, utilize this sheet-like gain configuration in such a way that phase and gain profiles are uniformly sampled and, to first order, yield high-quality (undistorted) beams. The zig-zag laser does this with a single plate, and should be capable of power levels up to several kilowatts. The disk laser is designed around a large number of plates, and should be capable of scaling to arbitrarily high power levels.

  12. Average Rate of Heat-Related Hospitalizations in 23 States, 2001-2010

    Data.gov (United States)

    U.S. Environmental Protection Agency — This map shows the 2001–2010 average rate of hospitalizations classified as “heat-related” by medical professionals in 23 states that participate in CDC’s...

  13. On the averaging of ratios of specific heats in a multicomponent planetary atmosphere

    Science.gov (United States)

    Dubisch, R.

    1974-01-01

    The use of adiabatic relations in the calculation of planetary atmospheres requires knowledge of the ratio of specific heats of a mixture of gases under various pressure and temperature conditions. It is shown that errors introduced by simple averaging of the ratio of specific heats in a multicomponent atmosphere can be roughly 0.4%. Therefore, the gamma-averaging error can become important when integrating through the atmosphere to a large depth.

  14. High Brightness, High Average Current Injector Development at Cornell

    CERN Document Server

    Sinclair, C K

    2005-01-01

    Cornell University is constructing a 100 mA average current, high brightness electron injector for a planned Energy Recovery Linac (ERL) hard X-ray synchrotron radiation source. This injector will employ a very high voltage DC gun with a negative electron affinity photoemission cathode. Relatively long duration electron pulses from the photocathode will be drift bunched, and accelerated to 5-15 MeV with five two-cell, 1300 MHz superconducting cavities. The total beam power will be limited to 575 kW by the DC and RF power sources. A genetic algorithm based computational optimization of this injector has resulted in simulated rms normalized emittances of 0.1 mm-mrad at 80 pC/bunch, and 0.7 mm-mrad at 1 nC/bunch. The many technical issues and their design solutions will be discussed. Construction of the gun and the SRF cavities is well underway. The schedule for completion, and the planned measurements, will be presented.

  15. Active cooling of pulse compression diffraction gratings for high energy, high average power ultrafast lasers.

    Science.gov (United States)

    Alessi, David A; Rosso, Paul A; Nguyen, Hoang T; Aasen, Michael D; Britten, Jerald A; Haefner, Constantin

    2016-12-26

    Laser energy absorption and subsequent heat removal from diffraction gratings in chirped pulse compressors poses a significant challenge in high repetition rate, high peak power laser development. In order to understand the average power limitations, we have modeled the time-resolved thermo-mechanical properties of current and advanced diffraction gratings. We have also developed and demonstrated a technique of actively cooling Petawatt scale, gold compressor gratings to operate at 600W of average power - a 15x increase over the highest average power petawatt laser currently in operation. Combining this technique with low absorption multilayer dielectric gratings developed in our group would enable pulse compressors for petawatt peak power lasers operating at average powers well above 40kW.

  16. Study of the average heat transfer coefficient at different distances between wind tunnel models

    Science.gov (United States)

    Gnyrya, A.; Korobkov, S.; Mokshin, D.; Koshin, A.

    2015-01-01

    The paper presents investigations of physical and climatic factors with regard to design and process variables having effect on heat transfer in the building model system at different distances between them in the airflow direction. The aim of this work is to improve energy efficiency of exterior walls of buildings. A method of physical simulation was used in experiments. Experimental results on the average values of the heat transfer coefficient in the building model system are presented herein. A series of experiments was carried out on a specific aerodynamic test bench including a subsonic wind tunnel, heat models and devices for giving thermal boundary conditions, transducers, and the record system equipment. The paper contains diagrams of the average heat transfer distribution at fixed Reynolds number and the airflow angle of attack; the average values of the heat transfer coefficient for each face and wind tunnel models as a whole at maximum, medium, and large distances between them. Intensification of the average heat transfer was observed on the downstream model faces depending on the distance between models.

  17. High heat flux loop heat pipes

    Science.gov (United States)

    North, Mark T.; Sarraf, David B.; Rosenfeld, John H.; Maidanik, Yuri F.; Vershinin, Sergey

    1997-01-01

    Loop Heat Pipes (LHPs) can transport very large thermal power loads, over long distances, through flexible, small diameter tubes and against high gravitational heads. While recent LHPs have transported as much as 1500 W, the peak heat flux through a LHP's evaporator has been limited to about 0.07 MW/m2. This limitation is due to the arrangement of vapor passages next to the heat load which is one of the conditions necessary to ensure self priming of the device. This paper describes work aimed at raising this limit by threefold to tenfold. Two approaches were pursued. One optimized the vapor passage geometry for the high heat flux conditions. The geometry improved the heat flow into the wick and working fluid. This approach also employed a finer pored wick to support higher vapor flow losses. The second approach used a bidisperse wick material within the circumferential vapor passages. The bidisperse material increased the thermal conductivity and the evaporative surface area in the region of highest heat flux, while providing a flow path for the vapor. Proof-of-concept devices were fabricated and tested for each approach. Both devices operated as designed and both demonstrated operation at a heat flux of 0.70 MW/m2. This performance exceeded the known state of the art by a factor of more than six for both conventional heat pipes and for loop heat pipes using ammonia. In addition, the bidisperse-wick device demonstrated boiling heat transfer coefficients up to 100,000 W/m2.K, and the fine pored device demonstrated an orientation independence with its performance essentially unaffected by whether its evaporator was positioned above, below or level with the condenser.

  18. Exponential approximation for daily average solar heating or photolysis. [of stratospheric ozone layer

    Science.gov (United States)

    Cogley, A. C.; Borucki, W. J.

    1976-01-01

    When incorporating formulations of instantaneous solar heating or photolytic rates as functions of altitude and sun angle into long range forecasting models, it may be desirable to replace the time integrals by daily average rates that are simple functions of latitude and season. This replacement is accomplished by approximating the integral over the solar day by a pure exponential. This gives a daily average rate as a multiplication factor times the instantaneous rate evaluated at an appropriate sun angle. The accuracy of the exponential approximation is investigated by a sample calculation using an instantaneous ozone heating formulation available in the literature.

  19. Average Natural Convective Heat Transfer of Air-cooled Condensing Heat Exchanger of Emergency Cooldown Tank - Effect of Tube Banks

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Seon Jeong; Lee, Hee Joon [Kookmin University, Seoul (Korea, Republic of); Kim, Myoung Jun; Moon, Joo Hyung; Bae, Youngmin; Kim, Young-In [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Recently emergency cooldown tank(ECT) is a great concern of passive cooling system for the safety of nuclear reactor. After the operation of a conventional passive cooling system for an extended period, however, the water level falls as a result of the evaporation from the ECT, as steam is emitted from the open top of the tank. In this study, the effect of heat transfer area at the air cooled condensing heat exchanger was investigated by changing 5×5 tube banks into 4×4 and 3×3. Moreover, each of air-side natural convective heat transfer coefficient of tube banks was compared to existing correlations. This study presents the effect of heat transfer area at air-cooled condensing heat exchanger. As heat transfer area decreased, the temperature of outlet increased. In other words, the cooling performance got lower with the decrease of heat transfer area. In addition, the average natural convective heat transfer coefficient was 15.3 W/m{sup 2}/K from the 4×4 tube banks, and 4.92 W/m{sup 2}/K from the 3×3 tube banks, which had quite a large error more than 46% especially with the value of 4×4 tube banks compared to the value from correlation equation. Therefore, according to this result, it is needed to measure the local heat transfer coefficient of vertical cylinder more elaborately in further study.

  20. High Average Current Electron Guns for High-Power FELs

    Science.gov (United States)

    2009-12-09

    FELs 10 Appendix B: Thermionic Injectors 11 Appendix C: Grid Fields and Bunch Emittance 13 Appendix D: PARMELA Simulation of an IOT Gun 16...Inductive Output Tube ( IOT ) amplifiers [32-34] and can generate average currents of ~1 A, peak currents of ~ 5-10 A, cathode-anode voltages of ~ 35...of grid wires, centered at z = zG and x = ±a, ±3a, ±5a, ..., is given by <D(JC,Z) = - X n = ±l.±3. Fa(x,z) Gn(x,z) ( C3 ) where *0 = (1 / 2

  1. Large Eddy/Reynolds-Averaged Navier-Stokes Simulations of CUBRC Base Heating Experiments

    Science.gov (United States)

    Salazar, Giovanni; Edwards, Jack R.; Amar, Adam J.

    2012-01-01

    ven with great advances in computational techniques and computing power during recent decades, the modeling of unsteady separated flows, such as those encountered in the wake of a re-entry vehicle, continues to be one of the most challenging problems in CFD. Of most interest to the aerothermodynamics community is accurately predicting transient heating loads on the base of a blunt body, which would result in reduced uncertainties and safety margins when designing a re-entry vehicle. However, the prediction of heat transfer can vary widely depending on the turbulence model employed. Therefore, selecting a turbulence model which realistically captures as much of the flow physics as possible will result in improved results. Reynolds Averaged Navier Stokes (RANS) models have become increasingly popular due to their good performance with attached flows, and the relatively quick turnaround time to obtain results. However, RANS methods cannot accurately simulate unsteady separated wake flows, and running direct numerical simulation (DNS) on such complex flows is currently too computationally expensive. Large Eddy Simulation (LES) techniques allow for the computation of the large eddies, which contain most of the Reynolds stress, while modeling the smaller (subgrid) eddies. This results in models which are more computationally expensive than RANS methods, but not as prohibitive as DNS. By complimenting an LES approach with a RANS model, a hybrid LES/RANS method resolves the larger turbulent scales away from surfaces with LES, and switches to a RANS model inside boundary layers. As pointed out by Bertin et al., this type of hybrid approach has shown a lot of promise for predicting turbulent flows, but work is needed to verify that these models work well in hypersonic flows. The very limited amounts of flight and experimental data available presents an additional challenge for researchers. Recently, a joint study by NASA and CUBRC has focused on collecting heat transfer data

  2. Volume Averaging Theory (VAT) based modeling and closure evaluation for fin-and-tube heat exchangers

    Science.gov (United States)

    Zhou, Feng; Catton, Ivan

    2012-10-01

    A fin-and-tube heat exchanger was modeled based on Volume Averaging Theory (VAT) in such a way that the details of the original structure was replaced by their averaged counterparts, so that the VAT based governing equations can be efficiently solved for a wide range of parameters. To complete the VAT based model, proper closure is needed, which is related to a local friction factor and a heat transfer coefficient of a Representative Elementary Volume (REV). The terms in the closure expressions are complex and sometimes relating experimental data to the closure terms is difficult. In this work we use CFD to evaluate the rigorously derived closure terms over one of the selected REVs. The objective is to show how heat exchangers can be modeled as a porous media and how CFD can be used in place of a detailed, often formidable, experimental effort to obtain closure for the model.

  3. High-average-power diode-pumped Yb: YAG lasers

    Energy Technology Data Exchange (ETDEWEB)

    Avizonis, P V; Beach, R; Bibeau, C M; Emanuel, M A; Harris, D G; Honea, E C; Monroe, R S; Payne, S A; Skidmore, J A; Sutton, S B

    1999-10-01

    A scaleable diode end-pumping technology for high-average-power slab and rod lasers has been under development for the past several years at Lawrence Livermore National Laboratory (LLNL). This technology has particular application to high average power Yb:YAG lasers that utilize a rod configured gain element. Previously, this rod configured approach has achieved average output powers in a single 5 cm long by 2 mm diameter Yb:YAG rod of 430 W cw and 280 W q-switched. High beam quality (M{sup 2} = 2.4) q-switched operation has also been demonstrated at over 180 W of average output power. More recently, using a dual rod configuration consisting of two, 5 cm long by 2 mm diameter laser rods with birefringence compensation, we have achieved 1080 W of cw output with an M{sup 2} value of 13.5 at an optical-to-optical conversion efficiency of 27.5%. With the same dual rod laser operated in a q-switched mode, we have also demonstrated 532 W of average power with an M{sup 2} < 2.5 at 17% optical-to-optical conversion efficiency. These q-switched results were obtained at a 10 kHz repetition rate and resulted in 77 nsec pulse durations. These improved levels of operational performance have been achieved as a result of technology advancements made in several areas that will be covered in this manuscript. These enhancements to our architecture include: (1) Hollow lens ducts that enable the use of advanced cavity architectures permitting birefringence compensation and the ability to run in large aperture-filling near-diffraction-limited modes. (2) Compound laser rods with flanged-nonabsorbing-endcaps fabricated by diffusion bonding. (3) Techniques for suppressing amplified spontaneous emission (ASE) and parasitics in the polished barrel rods.

  4. Eighth CW and High Average Power RF Workshop

    CERN Document Server

    2014-01-01

    We are pleased to announce the next Continuous Wave and High Average RF Power Workshop, CWRF2014, to take place at Hotel NH Trieste, Trieste, Italy from 13 to 16 May, 2014. This is the eighth in the CWRF workshop series and will be hosted by Elettra - Sincrotrone Trieste S.C.p.A. (www.elettra.eu). CWRF2014 will provide an opportunity for designers and users of CW and high average power RF systems to meet and interact in a convivial environment to share experiences and ideas on applications which utilize high-power klystrons, gridded tubes, combined solid-state architectures, high-voltage power supplies, high-voltage modulators, high-power combiners, circulators, cavities, power couplers and tuners. New ideas for high-power RF system upgrades and novel ways of RF power generation and distribution will also be discussed. CWRF2014 sessions will start on Tuesday morning and will conclude on Friday lunchtime. A visit to Elettra and FERMI will be organized during the workshop. ORGANIZING COMMITTEE (OC): Al...

  5. Average density and porosity of high-strength lightweight concrete

    Directory of Open Access Journals (Sweden)

    A.S. Inozemtcev

    2014-11-01

    Full Text Available The analysis results of high-strength lightweight concrete (HSLWC structure are presented in this paper. The X-ray tomography, optical microscopy and other methods are used for researching of average density and porosity. It has been revealed that mixtures of HSLWC with density 1300…1500 kg/m3 have a homogeneous structure. The developed concrete has a uniform distribution of the hollow filler and a uniform layer of cement-mineral matrix. The highly saturated gas phase which is divided by denser large particles of quartz sand and products of cement hydration in the contact area allow forming a composite material with low average density, big porosity (up to 40% and high strength (compressive strength is more than 40 MPa. Special modifiers increase adhesion, compacts structure in the contact area, decrease water absorption of high-strength lightweight concrete (up to 1 % and ensure its high water resistance (water resistance coefficient is more than 0.95.

  6. A high average power electro-optic switch using KTP

    Energy Technology Data Exchange (ETDEWEB)

    Ebbers, C.A.; Cook, W.M.; Velsko, S.P.

    1994-04-01

    High damage threshold, high thermal conductivity, and small thermo-optic coefficients make KTiOPO{sub 4} (KTP) an attractive material for use in a high average power Q-switch. However, electro-chromic damage and refractive index homogeneity have prevented the utilization of KTP in such a device in the past. This work shows that electro-chromic damage is effectively suppressed using capacitive coupling, and a KTP crystal can be Q-switched for 1.5 {times} 10{sup 9} shots without any detectable electro-chromic damage. In addition, KTP with the high uniformity and large aperture size needed for a KTP electro-optic Q-switch can be obtained from flux crystals grown at constant temperature. A thermally compensated, dual crystal KTP Q-switch, which successfully produced 50 mJ pulses with a pulse width of 8 ns (FWHM), has been constructed. In addition, in off-line testing the Q-switch showed less than 7% depolarization at an average power loading of 3.2 kW/cm{sup 2}.

  7. Heat equation inversion framework for average SAR calculation from magnetic resonance thermal imaging.

    Science.gov (United States)

    Alon, Leeor; Sodickson, Daniel K; Deniz, Cem M

    2016-10-01

    Deposition of radiofrequency (RF) energy can be quantified via electric field or temperature change measurements. Magnetic resonance imaging has been used as a tool to measure three dimensional small temperature changes associated with RF radiation exposure. When duration of RF exposure is long, conversion from temperature change to specific absorption rate (SAR) is nontrivial due to prominent heat-diffusion and conduction effects. In this work, we demonstrated a method for calculation of SAR via an inversion of the heat equation including heat-diffusion and conduction effects. This method utilizes high-resolution three dimensional magnetic resonance temperature images and measured thermal properties of the phantom to achieve accurate calculation of SAR. Accuracy of the proposed method was analyzed with respect to operating frequency of a dipole antenna and parameters used in heat equation inversion. Bioelectromagnetics. 37:493-503, 2016. © 2016 Wiley Periodicals, Inc.

  8. Average Heating Rate of Hot Atmospheres in Distant Galaxy Clusters by Radio AGN: Evidence for Continuous AGN Heating

    Science.gov (United States)

    Ma, Cheng-Jiun; McNamara, B.; Nulsen, P.; Schaffer, R.

    2011-09-01

    X-ray observations of nearby clusters and galaxies have shown that energetic feedback from AGN is heating hot atmospheres and is probably the principal agent that is offsetting cooling flows. Here we examine AGN heating in distant X-ray clusters by cross correlating clusters selected from the 400 Square Degree X-ray Cluster survey with radio sources in the NRAO VLA Sky Survey. The jet power for each radio source was determined using scaling relations between radio power and cavity power determined for nearby clusters, groups, and galaxies with atmospheres containing X-ray cavities. Roughly 30% of the clusters show radio emission above a flux threshold of 3 mJy within the central 250 kpc that is presumably associated with the brightest cluster galaxy. We find no significant correlation between radio power, hence jet power, and the X-ray luminosities of clusters in redshift range 0.1 -- 0.6. The detection frequency of radio AGN is inconsistent with the presence of strong cooling flows in 400SD, but cannot rule out the presence of weak cooling flows. The average jet power of central radio AGN is approximately 2 10^{44} erg/s. The jet power corresponds to an average heating of approximately 0.2 keV/particle for gas within R_500. Assuming the current AGN heating rate remained constant out to redshifts of about 2, these figures would rise by a factor of two. Our results show that the integrated energy injected from radio AGN outbursts in clusters is statistically significant compared to the excess entropy in hot atmospheres that is required for the breaking of self-similarity in cluster scaling relations. It is not clear that central AGN in 400SD clusters are maintained by a self-regulated feedback loop at the base of a cooling flow. However, they may play a significant role in preventing the development of strong cooling flows at early epochs.

  9. Estimation of catchment averaged sensible heat fluxes using a large aperture scintillometer

    Directory of Open Access Journals (Sweden)

    Samain Bruno

    2012-05-01

    Full Text Available Evapotranspiration rates at the catchment scale are very difficult to quantify. One possible manner to continuously observe this variable could be the estimation of sensible heat fluxes (H across large distances (in the order of kilometers using a large aperture scintillometer (LAS, and inverting these observations into evapotranspiration rates, under the assumption that the LAS observations are representative for the entire catchment. The objective of this paper is to assess whether measured sensible heat fluxes from a LAS over a long distance (9.5 km can be assumed to be valid for a 102.3 km2 heterogeneous catchment. Therefore, a fully process-based water and energy balance model with a spatial resolution of 50 m has been thoroughly calibrated and validated for the Bellebeek catchmentin Belgium. A footprint analysis has been performed. In general, the sensible heat fluxes from the LAS compared well with the modeled sensible heat fluxes within the footprint. Moreover, as the modeled Hwithin the footprint has been found to be almost equal to the modeled catchment averaged H, it can be concluded that the scintillometer measurements over a distance of 9.5 km and an effective heightof 68 m are representative for the entire catchment.

  10. Estimation of heat load in waste tanks using average vapor space temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Crowe, R.D.; Kummerer, M.; Postma, A.K.

    1993-12-01

    This report describes a method for estimating the total heat load in a high-level waste tank with passive ventilation. This method relates the total heat load in the tank to the vapor space temperature and the depth of waste in the tank. Q{sub total} = C{sub f} (T{sub vapor space {minus}} T{sub air}) where: C{sub f} = Conversion factor = (R{sub o}k{sub soil}{sup *}area)/(z{sub tank} {minus} z{sub surface}); R{sub o} = Ratio of total heat load to heat out the top of the tank (function of waste height); Area = cross sectional area of the tank; k{sub soil} = thermal conductivity of soil; (z{sub tank} {minus} z{sub surface}) = effective depth of soil covering the top of tank; and (T{sub vapor space} {minus} T{sub air}) = mean temperature difference between vapor space and the ambient air at the surface. Three terms -- depth, area and ratio -- can be developed from geometrical considerations. The temperature difference is measured for each individual tank. The remaining term, the thermal conductivity, is estimated from the time-dependent component of the temperature signals coming from the periodic oscillations in the vapor space temperatures. Finally, using this equation, the total heat load for each of the ferrocyanide Watch List tanks is estimated. This provides a consistent way to rank ferrocyanide tanks according to heat load.

  11. High Temperature Heat Exchanger Project

    Energy Technology Data Exchange (ETDEWEB)

    Anthony E. Hechanova, Ph.D.

    2008-09-30

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

  12. High-gain Yb:YAG amplifier for ultrashort pulse laser at high-average power

    Science.gov (United States)

    Vetrovec, John; Copeland, Drew A.; Litt, Amardeep S.; Du, Detao

    2016-03-01

    We report on a Yb:YAG laser amplifier for ultrashort pulse applications at kW-class average power. The laser uses two large-aperture, disk-type gain elements fabricated from composite ceramic YAG material, and a multi-pass extraction architecture to obtain high gain in a chirped-pulse amplification system. The disks are edge-pumped, thus allowing for reduced doping of host material with laser ions, which translates to lower lasing threshold and lower heat dissipation in the Yb:YAG material. The latter makes it possible to amplify a near diffraction-limited seed without significant thermo-optical distortions. This work presents results of testing the laser amplifier with relay optics configured for energy extraction with up to 40 passes through the disks. Applications for the ultrashort pulse laser amplifier include producing laser-induced plasma channel, laser material ablation, and laser acceleration of atomic particles.

  13. A high-average-power FEL for industrial applications

    Energy Technology Data Exchange (ETDEWEB)

    Dylla, H.F.; Benson, S.; Bisognano, J.

    1995-12-31

    CEBAF has developed a comprehensive conceptual design of an industrial user facility based on a kilowatt UV (150-1000 nm) and IR (2-25 micron) FEL driven by a recirculating, energy-recovering 200 MeV superconducting radio-frequency (SRF) accelerator. FEL users{endash}CEBAF`s partners in the Laser Processing Consortium, including AT&T, DuPont, IBM, Northrop-Grumman, 3M, and Xerox{endash}plan to develop applications such as polymer surface processing, metals and ceramics micromachining, and metal surface processing, with the overall effort leading to later scale-up to industrial systems at 50-100 kW. Representative applications are described. The proposed high-average-power FEL overcomes limitations of conventional laser sources in available power, cost-effectiveness, tunability and pulse structure. 4 refs., 3 figs., 2 tabs.

  14. High speed laser drilling of metals using a high repetition rate, high average power ultrafast fiber CPA system.

    Science.gov (United States)

    Ancona, A; Röser, F; Rademaker, K; Limpert, J; Nolte, S; Tünnermann, A

    2008-06-09

    We present an experimental study on the drilling of metal targets with ultrashort laser pulses at high repetition rates (from 50 kHz up to 975 kHz) and high average powers (up to 68 Watts), using an ytterbium-doped fiber CPA system. The number of pulses to drill through steel and copper sheets with thicknesses up to 1 mm have been measured as a function of the repetition rate and the pulse energy. Two distinctive effects, influencing the drilling efficiency at high repetition rates, have been experimentally found and studied: particle shielding and heat accumulation. While the shielding of subsequent pulses due to the ejected particles leads to a reduced ablation efficiency, this effect is counteracted by heat accumulation. The experimental data are in good qualitative agreement with simulations of the heat accumulation effect and previous studies on the particle emission. However, for materials with a high thermal conductivity as copper, both effects are negligible for the investigated processing parameters. Therefore, the full power of the fiber CPA system can be exploited, which allows to trepan high-quality holes in 0.5mm-thick copper samples with breakthrough times as low as 75 ms.

  15. HIGH AVERAGE POWER UV FREE ELECTRON LASER EXPERIMENTS AT JLAB

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, David; Evtushenko, Pavel; Gubeli, Joseph; Hernandez-Garcia, Carlos; Legg, Robert; Neil, George; Powers, Thomas; Shinn, Michelle D; Tennant, Christopher

    2012-07-01

    Having produced 14 kW of average power at {approx}2 microns, JLAB has shifted its focus to the ultraviolet portion of the spectrum. This presentation will describe the JLab UV Demo FEL, present specifics of its driver ERL, and discuss the latest experimental results from FEL experiments and machine operations.

  16. Picosecond mid-infrared amplifier for high average power.

    CSIR Research Space (South Africa)

    Botha, LR

    2007-04-01

    Full Text Available are similar. The saturation fluence for a multi level system can be written as z PhEsat σ υ 2 = With σ the stimulated emission cross section and P the pressure of the laser. 1/z... is essentially the average number of populated rotational levels. For our case z=0.07 and 181054.1 −×=σ cm2. Thus for a 10 atm laser the saturation fluence is: 2 18 1334 /1173 07.01017/12 10109.210626.6 cmmJxEsat = ××× ××× = − − The maximum...

  17. A Comparative Study of the Harmonic and Arithmetic Averaging of Diffusion Coefficients for Non-linear Heat Conduction Problems

    Energy Technology Data Exchange (ETDEWEB)

    Samet Y. Kadioglu; Robert R. Nourgaliev; Vincent A. Mousseau

    2008-03-01

    We perform a comparative study for the harmonic versus arithmetic averaging of the heat conduction coefficient when solving non-linear heat transfer problems. In literature, the harmonic average is the method of choice, because it is widely believed that the harmonic average is more accurate model. However, our analysis reveals that this is not necessarily true. For instance, we show a case in which the harmonic average is less accurate when a coarser mesh is used. More importantly, we demonstrated that if the boundary layers are finely resolved, then the harmonic and arithmetic averaging techniques are identical in the truncation error sense. Our analysis further reveals that the accuracy of these two techniques depends on how the physical problem is modeled.

  18. Compact High Efficiency Adsorption Heat Pump

    OpenAIRE

    TeGrotenhuis, Ward E; Humble, Paul H; Sweeney, Josh B

    2012-01-01

    An innovative adsorption cycle heat pump technology is presented that is compact and capable of achieving high energy efficiency for integrated space heating, air conditioning, and water heating. High energy efficiency is accomplished by effectively recuperating heat within the system to minimize energy consumption. This substantially reduces the thermodynamic losses that occur when the sorbent beds are thermally cycled without effective heat recuperation. Furthermore, equipment cost is reduc...

  19. Occupational exposure assessment of magnetic fields generated by induction heating equipment-the role of spatial averaging.

    Science.gov (United States)

    Kos, Bor; Valič, Blaž; Kotnik, Tadej; Gajšek, Peter

    2012-10-07

    Induction heating equipment is a source of strong and nonhomogeneous magnetic fields, which can exceed occupational reference levels. We investigated a case of an induction tempering tunnel furnace. Measurements of the emitted magnetic flux density (B) were performed during its operation and used to validate a numerical model of the furnace. This model was used to compute the values of B and the induced in situ electric field (E) for 15 different body positions relative to the source. For each body position, the computed B values were used to determine their maximum and average values, using six spatial averaging schemes (9-285 averaging points) and two averaging algorithms (arithmetic mean and quadratic mean). Maximum and average B values were compared to the ICNIRP reference level, and E values to the ICNIRP basic restriction. Our results show that in nonhomogeneous fields, the maximum B is an overly conservative predictor of overexposure, as it yields many false positives. The average B yielded fewer false positives, but as the number of averaging points increased, false negatives emerged. The most reliable averaging schemes were obtained for averaging over the torso with quadratic averaging, with no false negatives even for the maximum number of averaging points investigated.

  20. Absorption heat pump with an average efficiency of 140%. Absorptiewarmtepomp haalt gemiddeld rendement van 140%

    Energy Technology Data Exchange (ETDEWEB)

    Langreck, J. (Colibri BV, Landgraaf (Netherlands))

    1994-09-01

    A description is given of a new type of absorption heat pump in which ammonia/water is applied as the working fluid. With the first sample in the provincial government building in Maastricht, Netherlands, and efficiency of 140% has been realized. A brief overview is given of the costs of and the market for this new type of heat pump. 2 figs., 1 ill., 3 tabs., 1 ref.

  1. Heat transfer interface between a high temperature heat source and a heat sink

    Energy Technology Data Exchange (ETDEWEB)

    du Pre, F.K.; Jaspers, H.A.

    1977-10-11

    A heat-transfer interface between and separating a high temperature heat source and a heat sink is formed by the adjacent walls of the heat source and heat sink with a thin gap between these walls and helium gas sealed in the gap, the walls preferably defining concentric hemispheres; this interface being particularly feasible as separable walls of the heater portion of a Stirling engine and a heat source.

  2. Cesium telluride cathodes for the next generation of high-average current high-brightness photoinjectors

    Energy Technology Data Exchange (ETDEWEB)

    Filippetto, D., E-mail: dfilippetto@lbl.gov; Qian, H.; Sannibale, F. [Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720 (United States)

    2015-07-27

    We report on the performances of a Cs{sub 2}Te photocathode under extreme conditions of high peak time-dependent accelerating fields, continuous wave operations, and MHz pulse extraction with up to 0.3 mA average current. The measurements, performed in a normal conducting cavity, show extended lifetime and robustness, elucidate the main mechanisms for cathode degradation, and set the required system vacuum performance for compatibility with the operations of a high average power X-ray free electron laser user facility, opening the doors to the next generation of MHz-scale ultrafast scientific instruments.

  3. Diode-Pumped High Energy and High Average Power All-Solid-State Picosecond Amplifier Systems

    OpenAIRE

    Jiaxing Liu; Wei Wang; Zhaohua Wang; Zhiguo Lv; Zhiyuan Zhang; Zhiyi Wei

    2015-01-01

    We present our research on the high energy picosecond laser operating at a repetition rate of 1 kHz and the high average power picosecond laser running at 100 kHz based on bulk Nd-doped crystals. With diode-pumped solid state (DPSS) hybrid amplifiers consisting of a picosecond oscillator, a regenerative amplifier, end-pumped single-pass amplifiers, and a side-pumped amplifier, an output energy of 64.8 mJ at a repetition rate of 1 kHz was achieved. An average power of 37.5 W at a repetition ra...

  4. Diode-Pumped High Energy and High Average Power All-Solid-State Picosecond Amplifier Systems

    Directory of Open Access Journals (Sweden)

    Jiaxing Liu

    2015-12-01

    Full Text Available We present our research on the high energy picosecond laser operating at a repetition rate of 1 kHz and the high average power picosecond laser running at 100 kHz based on bulk Nd-doped crystals. With diode-pumped solid state (DPSS hybrid amplifiers consisting of a picosecond oscillator, a regenerative amplifier, end-pumped single-pass amplifiers, and a side-pumped amplifier, an output energy of 64.8 mJ at a repetition rate of 1 kHz was achieved. An average power of 37.5 W at a repetition rate of 100 kHz pumped by continuous wave laser diodes was obtained. Compact, stable and high power DPSS laser amplifier systems with good beam qualities are excellent picosecond sources for high power optical parametric chirped pulse amplification (OPCPA and high-efficiency laser processing.

  5. High Temperature Thermoacoustic Heat Pump

    Energy Technology Data Exchange (ETDEWEB)

    Tijani, H.; Spoelstra, S. [ECN Biomass and Energy Efficiency, Petten (Netherlands)

    2012-07-15

    Thermoacoustic technology can provide new types of heat pumps that can be deployed in different applications. Thermoacoustic heat pumps can for example be applied in dwellings to generate cooling or heating. Typically, space and water heating makes up about 60% of domestic and office energy consumption. The application of heat pumps can contribute to achieve energy savings and environmental benefits by reducing CO2 and NOx emissions. This paper presents the study of a laboratory scale thermoacoustic-Stirling heat pump operating between 10C and 80C which can be applied in domestics and offices. The heat pump is driven by a thermoacoustic-Stirling engine. The experimental results show that the heat pump pumps 250 W of heat at 60C at a drive ratio of 3.6 % and 200 W at 80C at a drive ratio of 3.5 %. The performance for both cases is about 40% of the Carnot performance. The design, construction, and performance measurements of the heat pump will be presented and discussed.

  6. Average Heating Rate of Hot Atmospheres in Distant Clusters by Radio AGN: Evidence for Continuous AGN Heating

    CERN Document Server

    Ma, C -J; Nulsen, P E J; Schaffer, R; Vikhlinin, A

    2011-01-01

    X-ray observations of nearby clusters and galaxies have shown that energetic feedback from active galactic nuclei (AGN) is heating hot atmospheres and is probably the principal agent that is offsetting cooling flows. Here we examine AGN heating in distant X-ray clusters by cross correlating clusters selected from the 400 Square Degree X-ray Cluster survey with radio sources in the NRAO VLA Sky Survey. The jet power for each radio source was determined using scaling relations between radio power and cavity power determined for nearby clusters, groups, and galaxies with atmospheres containing X-ray cavities. Roughly 30% of the clusters show radio emission above a flux threshold of 3 mJy within the central 250 kpc that is presumably associated with the brightest cluster galaxy. We find no significant correlation between radio power, hence jet power, and the X-ray luminosities of clusters in redshift range 0.1 - 0.6. The detection frequency of radio AGN is inconsistent with the presence of strong cooling flows in...

  7. APS high heat load monochromator

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W.K.; Mills, D.

    1993-02-01

    This document contains the design specifications of the APS high heat load (HHL) monochromator and associated accessories as of February 1993. It should be noted that work is continuing on many parts of the monochromator including the mechanical design, crystal cooling designs, etc. Where appropriate, we have tried to add supporting documentation, references to published papers, and calculations from which we based our decisions. The underlying philosophy behind performance specifications of this monochromator was to fabricate a device that would be useful to as many APS users as possible, that is, the design should be as generic as possible. In other words, we believe that this design will be capable of operating on both bending magnet and ID beamlines (with the appropriate changes to the cooling and crystals) with both flat and inclined crystal geometries and with a variety of coolants. It was strongly felt that this monochromator should have good energy scanning capabilities over the classical energy range of about 4 to 20 keywith Si (111) crystals. For this reason, a design incorporating one rotation stage to drive both the first and second crystals was considered most promising. Separate rotary stages for the first and second crystals can sometimes provide more flexibility in their capacities to carry heavy loads (for heavily cooled first crystals or sagittal benders of second crystals), but their tuning capabilities were considered inferior to the single axis approach.

  8. Development of high effectiveness droplet heat exchangers

    Science.gov (United States)

    Thayer, W. J., III; Sekins, K. M.; Bruckner, A. P.

    1985-04-01

    An experimental and analytical investigation has been carried out to assess the feasibility of developing high effectiveness, high temperature droplet heat exchangers and to identify practical applications for this type of direct contact heat exchanger. The droplet heat exchanger (DHX) concept studies uses a counterflowing gas and droplet configuration, uniformly sized droplets or particles, and a uniform dispersion of droplets in gas to achieve high heat exchanger effectiveness. Direct contact between the heat transfer media eliminates the solid heat transfer surfaces that are used in conventional heat exchangers and is expected to make very high temperature heat transfer practical. Low temperature simulation tests and analysis have been used to demonstrate that uniformly sized droplets can be generated over a wide range of fluid properties and operating conditions appropriate for high temperature droplet heat exchanger applications. One- and two-dimensional, two-phase flow and heat transfer computer models have been developed and used to characterize both individual component configurations and overall DHX heat transfer rates and effectiveness. The computer model and test data began to diverge as the operating pressure was increased, indicating a need for more general transport rate correlations and a better understanding of the two-phase flows that govern DHX operation.

  9. High average power coherent vuv generation at 10 MHz repetition frequency by intracavity high harmonic generation.

    Science.gov (United States)

    Ozawa, Akira; Zhao, Zhigang; Kuwata-Gonokami, Makoto; Kobayashi, Yohei

    2015-06-15

    Intracavity high harmonic generation was utilized to generate high average-power coherent radiation at vacuum ultraviolet (vuv) wavelengths. A ytterbium-doped fiber-laser based master-oscillator power-amplifier (MOPA) system with a 10 MHz repetition frequency was developed and used as a driving laser for an external cavity. A series of odd-order harmonic radiations was generated extending down to ∼ 30 nm (41 eV in photon energy). The 7th harmonic radiation generated was centered at 149 nm and had an average output power of up to 0.5 mW. In this way, we developed a sub-mW coherent vuv-laser with a 10 MHz repetition frequency, which, if used as an excitation laser source for photo-electron spectroscopy, could improve the signal count-rate without deterioration of the spectral-resolution caused by space-charge effects.

  10. Crossatron switch as thyratron replacement in high repetition rate, high average power modulators

    Science.gov (United States)

    Sullivan, J. S.

    1988-06-01

    The Crossatron is a cold cathode, low pressure, gas discharge switch with opening and closing capabilities. Due to its cold cathode operation, the Crossatron may offer lifetime advantages compared to the hydrogen thyratron. Unfortunately, little information regarding Crossatron lifetime and performance in high repetition rate, high average power, pulse modulators exists. Four prototype Crossatron devices, fabricated by Hughes Aircraft, were obtained to evaluate their performance and lifetime in high repetition rate, high average power, pulse modulators that had previously been equipped with hydrogen thyratrons. The prototype Crossatrons were evaluated over a range of operating parameters. Various grid drive, keep alive power levels and triggering schemes were employed in the tests. Switch parameters such as trigger time, anode fall time, jitter, recovery time, peak di/dt, switch efficiency, and the gas pumping effect of the discharge were observed. One Crossatron prototype was also subjected to lifetime tests that accumulated tens of billions of pulses. Lifetime data will be compared to various thyratron models tested similarly.

  11. High-throughput machining using high average power ultrashort pulse lasers and ultrafast polygon scanner

    Science.gov (United States)

    Schille, Joerg; Schneider, Lutz; Streek, André; Kloetzer, Sascha; Loeschner, Udo

    2016-03-01

    In this paper, high-throughput ultrashort pulse laser machining is investigated on various industrial grade metals (Aluminium, Copper, Stainless steel) and Al2O3 ceramic at unprecedented processing speeds. This is achieved by using a high pulse repetition frequency picosecond laser with maximum average output power of 270 W in conjunction with a unique, in-house developed two-axis polygon scanner. Initially, different concepts of polygon scanners are engineered and tested to find out the optimal architecture for ultrafast and precision laser beam scanning. Remarkable 1,000 m/s scan speed is achieved on the substrate, and thanks to the resulting low pulse overlap, thermal accumulation and plasma absorption effects are avoided at up to 20 MHz pulse repetition frequencies. In order to identify optimum processing conditions for efficient high-average power laser machining, the depths of cavities produced under varied parameter settings are analyzed and, from the results obtained, the characteristic removal values are specified. The maximum removal rate is achieved as high as 27.8 mm3/min for Aluminium, 21.4 mm3/min for Copper, 15.3 mm3/min for Stainless steel and 129.1 mm3/min for Al2O3 when full available laser power is irradiated at optimum pulse repetition frequency.

  12. Sensitivity of Displaced-Beam Scintillometer Measurements of Area-Average Heat Fluxes to Uncertainties in Topographic Heights

    CERN Document Server

    Gruber, Matthew; Hartogensis, Oscar

    2014-01-01

    Displaced-beam scintillometer measurements of the turbulence inner-scale length $l_o$ and refractive index structure function $C_n^2$ resolve area-average turbulent fluxes of heat and momentum through the Monin-Obukhov similarity equations. Sensitivity studies have been produced for the use of displaced-beam scintillometers over flat terrain. Many real field sites feature variable topography. We develop here an analysis of the sensitivity of displaced-beam scintillometer derived sensible heat fluxes to uncertainties in spacially distributed topographic measurements. Sensitivity is shown to be concentrated in areas near the center of the beam and where the underlying topography is closest to the beam height. Uncertainty may be decreased by taking precise topographic measurements in these areas.

  13. Femtosecond and picosecond laser drilling of metals at high repetition rates and average powers.

    Science.gov (United States)

    Ancona, A; Döring, S; Jauregui, C; Röser, F; Limpert, J; Nolte, S; Tünnermann, A

    2009-11-01

    The influence of pulse duration on the laser drilling of metals at repetition rates of up to 1 MHz and average powers of up to 70 W has been experimentally investigated using an ytterbium-doped-fiber chirped-pulse amplification system with pulses from 800 fs to 19 ps. At a few hundred kilohertz particle shielding causes an increase in the number of pulses for breakthrough, depending on the pulse energy and duration. At higher repetition rates, the heat accumulation effect overbalances particle shielding, but significant melt ejection affects the hole quality. Using femtosecond pulses, heat accumulation starts at higher repetition rates, and the ablation efficiency is higher compared with picosecond pulses.

  14. Numerical Investigation of Thermal Effect in Plasma Electrode Pockels Cell for High Average Power

    Institute of Scientific and Technical Information of China (English)

    CAO Ding-Xiang; ZHANG Xiong-Jun; ZHENG Wan-Guo; HE Shao-Bo; SUI Zhan

    2006-01-01

    @@ The average power of a Pockels cell is limited by thermal effects arising from the optical absorption of the laser pulse. These thermal effects can be managed by configuring the switch as a plasma-electrode thin plate Pockels cell, which works under heat-capacity operation. Simulation results show that, based on KD*P (in thickness 0.5cm) at an average power loading of 1 kW, the aperture integrated depolarization loss at 1.06 um is less than 10% in 5min working time.

  15. Thermal distortion and birefringence in repetition-rate plasma electrode Pockels cell for high average power

    Institute of Scientific and Technical Information of China (English)

    Dingxiang Cao; Xiongjun Zhang; Wanguo Zheng; Shaobo He; Zhan Sui

    2007-01-01

    We numerically study thermally induced birefringence and distortion in plasma electrode Pockels cell based on KD*P as the electro-optic material. This device can repetitively operate under the heat capacity mode.Simulation results indicate that the excellent switching performances and low wave-front distortion are achieved within several tens seconds working time at average power in excess of 1 kW.

  16. Modeling of a heat sink and high heat flux vapor chamber

    Science.gov (United States)

    Vadnjal, Aleksander

    An increasing demand for a higher heat flux removal capability within a smaller volume for high power electronics led us to focus on a novel cold plate design. A high heat flux evaporator and micro channel heat sink are the main components of a cold plate which is capable of removing couple of 100 W/cm2. In order to describe performance of such porous media device a proper modeling has to be addressed. A universal approach based on the volume average theory (VAT) to transport phenomena in porous media is shown. An approach on how to treat the closure for momentum and energy equations is addressed and a proper definition for friction factors and heat transfer coefficients are discussed. A numerical scheme using a solution to Navier-Stokes equations over a representative elementary volume (REV) and the use of VAT is developed to show how to compute friction factors and heat transfer coefficients. The calculation show good agreement with the experimental data. For the heat transfer coefficient closure, a proper average for both fluid and solid is investigated. Different types of heating are also investigated in order to determine how it influences the heat transfer coefficient. A higher heat fluxes in small area condensers led us to the micro channels in contrast to the classical heat fin design. A micro channel can have various shapes to enhance heat transfer, but the shape that will lead to a higher heat flux removal with a moderate pumping power needs to be determined. The standard micro-channel terminology is usually used for channels with a simple cross section, e.g. square, round, triangle, etc., but here the micro channel cross section is going to be expanded to describe more complicated and interconnected micro scale channel cross sections. The micro channel geometries explored are pin fins (in-line and staggered) and sintered porous micro channels. The problem solved here is a conjugate problem involving two heat transfer mechanisms; (1) porous media

  17. The Effect of Cumulus Cloud Field Anisotropy on Domain-Averaged Solar Fluxes and Atmospheric Heating Rates

    Science.gov (United States)

    Hinkelman, Laura M.; Evans, K. Franklin; Clothiaux, Eugene E.; Ackerman, Thomas P.; Stackhouse, Paul W., Jr.

    2006-01-01

    Cumulus clouds can become tilted or elongated in the presence of wind shear. Nevertheless, most studies of the interaction of cumulus clouds and radiation have assumed these clouds to be isotropic. This paper describes an investigation of the effect of fair-weather cumulus cloud field anisotropy on domain-averaged solar fluxes and atmospheric heating rate profiles. A stochastic field generation algorithm was used to produce twenty three-dimensional liquid water content fields based on the statistical properties of cloud scenes from a large eddy simulation. Progressively greater degrees of x-z plane tilting and horizontal stretching were imposed on each of these scenes, so that an ensemble of scenes was produced for each level of distortion. The resulting scenes were used as input to a three-dimensional Monte Carlo radiative transfer model. Domain-average transmission, reflection, and absorption of broadband solar radiation were computed for each scene along with the average heating rate profile. Both tilt and horizontal stretching were found to significantly affect calculated fluxes, with the amount and sign of flux differences depending strongly on sun position relative to cloud distortion geometry. The mechanisms by which anisotropy interacts with solar fluxes were investigated by comparisons to independent pixel approximation and tilted independent pixel approximation computations for the same scenes. Cumulus anisotropy was found to most strongly impact solar radiative transfer by changing the effective cloud fraction, i.e., the cloud fraction when the field is projected on a surface perpendicular to the direction of the incident solar beam.

  18. Icodextrin improves metabolic and fluid management in high and high-average transport diabetic patients.

    Science.gov (United States)

    Paniagua, Ramón; Ventura, María-de-Jesús; Avila-Díaz, Marcela; Cisneros, Alejandra; Vicenté-Martínez, Marlén; Furlong, María-Del-Carmen; García-González, Zuzel; Villanueva, Diana; Orihuela, Oscar; Prado-Uribe, María-Del-Carmen; Alcántara, Guadalupe; Amato, Dante

    2009-01-01

    Icodextrin-based solutions (ICO) have clinical and theoretical advantages over glucose-based solutions (GLU) in fluid and metabolic management of diabetic peritoneal dialysis (PD) patients; however, these advantages have not yet been tested in a randomized fashion. To analyze the effects of ICO on metabolic and fluid control in high and high-average transport diabetic patients on continuous ambulatory PD (CAPD). A 12-month, multicenter, open-label, randomized controlled trial was conducted to compare ICO (n = 30) versus GLU (n = 29) in diabetic CAPD patients with high-average and high peritoneal transport characteristics. The basic daily schedule was 3 x 2 L GLU (1.5%) and either 1 x 2 L ICO (7.5%) or 1 x 2 L GLU (2.5%) for the long-dwell exchange, with substitution of 2.5% or 4.25% for 1.5% GLU being allowed when clinically necessary. Variables related to metabolic and fluid control were measured each month. Groups were similar at baseline in all measured variables. More than 66% of the patients using GLU, but only 9% using ICO, needed prescriptions of higher glucose concentration solutions. Ultrafiltration (UF) was higher (198 +/- 101 mL/day, p ICO group than in the GLU group over time. Changes from baseline were more pronounced in the ICO group than in the GLU group for extracellular fluid volume (0.23 +/- 1.38 vs -1.0 +/- 1.48 L, p ICO group had better metabolic control than those in the GLU group: glucose absorption was more reduced (-17 +/- 44 vs -64 +/- 35 g/day) as were insulin needs (3.6 +/- 3.4 vs - 9.1 +/- 4.7 U/day, p ICO group had fewer adverse events related to fluid and glucose control than patients in the GLU group. Icodextrin represents a significant advantage in the management of high transport diabetic patients on PD, improving peritoneal UF and fluid control and reducing the burden of glucose overexposure, thereby facilitating metabolic control.

  19. Average Transient Lifetime and Lyapunov Dimension for Transient Chaos in a High-Dimensional System

    Institute of Scientific and Technical Information of China (English)

    陈洪; 汤建新; 唐少炎; 向红; 陈新

    2001-01-01

    The average transient lifetime of a chaotic transient versus the Lyapunov dimension of a chaotic saddle is studied for high-dimensional nonlinear dynamical systems. Typically the average lifetime depends upon not only the system parameter but also the Lyapunov dimension of the chaotic saddle. The numerical example uses the delayed feedback differential equation.

  20. High performance heat pump absorption cycles

    Energy Technology Data Exchange (ETDEWEB)

    Lazzarin, R.; Longo, G.; Rossetto, L.

    1988-10-01

    Absorption heat pumps can provide high performances when operating in suitable cycles with multiple effects. This report describes some multistage cycles and evaluates the coefficient of performance realistically obtainable both in winter and summer working conditions.

  1. Design of a high average-power FEL driven by an existing 20 MV electrostatic-accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kimel, I.; Elias, L.R. [Univ. of Central Florida, Orlando, FL (United States)

    1995-12-31

    There are some important applications where high average-power radiation is required. Two examples are industrial machining and space power-beaming. Unfortunately, up to date no FEL has been able to show more than 10 Watts of average power. To remedy this situation we started a program geared towards the development of high average-power FELs. As a first step we are building in our CREOL laboratory, a compact FEL which will generate close to 1 kW in CW operation. As the next step we are also engaged in the design of a much higher average-power system based on a 20 MV electrostatic accelerator. This FEL will be capable of operating CW with a power output of 60 kW. The idea is to perform a high power demonstration using the existing 20 MV electrostatic accelerator at the Tandar facility in Buenos Aires. This machine has been dedicated to accelerate heavy ions for experiments and applications in nuclear and atomic physics. The necessary adaptations required to utilize the machine to accelerate electrons will be described. An important aspect of the design of the 20 MV system, is the electron beam optics through almost 30 meters of accelerating and decelerating tubes as well as the undulator. Of equal importance is a careful design of the long resonator with mirrors able to withstand high power loading with proper heat dissipation features.

  2. Cyclic high temperature heat storage using borehole heat exchangers

    Science.gov (United States)

    Boockmeyer, Anke; Delfs, Jens-Olaf; Bauer, Sebastian

    2016-04-01

    The transition of the German energy supply towards mainly renewable energy sources like wind or solar power, termed "Energiewende", makes energy storage a requirement in order to compensate their fluctuating production and to ensure a reliable energy and power supply. One option is to store heat in the subsurface using borehole heat exchangers (BHEs). Efficiency of thermal storage is increasing with increasing temperatures, as heat at high temperatures is more easily injected and extracted than at temperatures at ambient levels. This work aims at quantifying achievable storage capacities, storage cycle times, injection and extraction rates as well as thermal and hydraulic effects induced in the subsurface for a BHE storage site in the shallow subsurface. To achieve these aims, simulation of these highly dynamic storage sites is performed. A detailed, high-resolution numerical simulation model was developed, that accounts for all BHE components in geometrical detail and incorporates the governing processes. This model was verified using high quality experimental data and is shown to achieve accurate simulation results with excellent fit to the available experimental data, but also leads to large computational times due to the large numerical meshes required for discretizing the highly transient effects. An approximate numerical model for each type of BHE (single U, double U and coaxial) that reduces the number of elements and the simulation time significantly was therefore developed for use in larger scale simulations. The approximate numerical model still includes all BHE components and represents the temporal and spatial temperature distribution with a deviation of less than 2% from the fully discretized model. Simulation times are reduced by a factor of ~10 for single U-tube BHEs, ~20 for double U-tube BHEs and ~150 for coaxial BHEs. This model is then used to investigate achievable storage capacity, injection and extraction rates as well as induced effects for

  3. Determining Adequate Averaging Periods and Reference Coordinates for Eddy Covariance Measurements of Surface Heat and Water Vapor Fluxes over Mountainous Terrain

    Directory of Open Access Journals (Sweden)

    Yi-Ying Chen Ming-Hsu Li

    2012-01-01

    Full Text Available Two coordinate rotation approaches (double and planar-fit rotations and no rotation, in association with averaging periods of 15 - 480 min, were applied to compute surface heat and water vapor fluxes using the eddy covariance approach. Measurements were conducted in an experimental watershed, the Lien-Hua-Chih (LHC watershed, located in central Taiwan. For no rotation and double rotation approaches, an adequate averaging period of 15 or 30 min was suggested for better energy closure and small variations on energy closure fractions. For the planar-fit rotation approach, an adequate averaging period of 60 or 120 min was recommended, and a typical averaging period of 30 min is not superior to that of 60 or 120 min in terms of better energy closure and small variations on energy closure fractions. The Ogive function analysis revealed that the energy closure was improved with the increase of averaging time by capturing sensible heat fluxes at low-frequency ranges during certain midday hours at LHC site. Seasonal variations of daily energy closure fractions, high in dry season and low in wet season, were found to be associated with the surface dryness and strength of turbulent development. The mismatching of flux footprint areas among flux sensors was suggested as the cause of larger CF variations during the dry seasons as that indicated by the footprint analysis showing scattered source areas. During the wet season, the underestimation of turbulent fluxes by EC observations at the LHC site was attributed to weak turbulence developments as the source area identified by the footprint analysis was closer to the flux tower than those scattered in dry season.

  4. High thermal power density heat transfer apparatus providing electrical isolation at high temperature using heat pipes

    Science.gov (United States)

    Morris, J. F. (Inventor)

    1985-01-01

    This invention is directed to transferring heat from an extremely high temperature source to an electrically isolated lower temperature receiver. The invention is particularly concerned with supplying thermal power to a thermionic converter from a nuclear reactor with electric isolation. Heat from a high temperature heat pipe is transferred through a vacuum or a gap filled with electrically nonconducting gas to a cooler heat pipe. If the receiver requires gratr thermal power density, geometries are used with larger heat pipe areas for transmitting and receiving energy than the area for conducting the heat to the thermionic converter. In this way the heat pipe capability for increasing thermal power densities compensates for the comparative low thermal power densities through the electrically nonconducting gap between the two heat pipes.

  5. Vibrational resonance: a study with high-order word-series averaging

    CERN Document Server

    Murua, Ander

    2016-01-01

    We study a model problem describing vibrational resonance by means of a high-order averaging technique based on so-called word series. With the tech- nique applied here, the tasks of constructing the averaged system and the associ- ated change of variables are divided into two parts. It is first necessary to build recursively a set of so-called word basis functions and, after that, all the required manipulations involve only scalar coefficients that are computed by means of sim- ple recursions. As distinct from the situation with other approaches, with word- series, high-order averaged systems may be derived without having to compute the associated change of variables. In the system considered here, the construction of high-order averaged systems makes it possible to obtain very precise approxima- tions to the true dynamics.

  6. Improved performance of high average power semiconductor arrays for applications in diode pumped solid state lasers

    Energy Technology Data Exchange (ETDEWEB)

    Beach, R.; Emanuel, M.; Benett, W.; Freitas, B.; Ciarlo, D.; Carlson, N.; Sutton, S.; Skidmore, J.; Solarz, R.

    1994-01-01

    The average power performance capability of semiconductor diode laser arrays has improved dramatically over the past several years. These performance improvements, combined with cost reductions pursued by LLNL and others in the fabrication and packaging of diode lasers, have continued to reduce the price per average watt of laser diode radiation. Presently, we are at the point where the manufacturers of commercial high average power solid state laser systems used in material processing applications can now seriously consider the replacement of their flashlamp pumps with laser diode pump sources. Additionally, a low cost technique developed and demonstrated at LLNL for optically conditioning the output radiation of diode laser arrays has enabled a new and scalable average power diode-end-pumping architecture that can be simply implemented in diode pumped solid state laser systems (DPSSL`s). This development allows the high average power DPSSL designer to look beyond the Nd ion for the first time. Along with high average power DPSSL`s which are appropriate for material processing applications, low and intermediate average power DPSSL`s are now realizable at low enough costs to be attractive for use in many medical, electronic, and lithographic applications.

  7. Validity of a Wearable Accelerometer Device to Measure Average Acceleration Values During High-Speed Running.

    Science.gov (United States)

    Alexander, Jeremy P; Hopkinson, Trent L; Wundersitz, Daniel W T; Serpell, Benjamin G; Mara, Jocelyn K; Ball, Nick B

    2016-11-01

    Alexander, JP, Hopkinson, TL, Wundersitz, DWT, Serpell, BG, Mara, JK, and Ball, NB. Validity of a wearable accelerometer device to measure average acceleration values during high-speed running. J Strength Cond Res 30(11): 3007-3013, 2016-The aim of this study was to determine the validity of an accelerometer to measure average acceleration values during high-speed running. Thirteen subjects performed three sprint efforts over a 40-m distance (n = 39). Acceleration was measured using a 100-Hz triaxial accelerometer integrated within a wearable tracking device (SPI-HPU; GPSports). To provide a concurrent measure of acceleration, timing gates were positioned at 10-m intervals (0-40 m). Accelerometer data collected during 0-10 m and 10-20 m provided a measure of average acceleration values. Accelerometer data was recorded as the raw output and filtered by applying a 3-point moving average and a 10-point moving average. The accelerometer could not measure average acceleration values during high-speed running. The accelerometer significantly overestimated average acceleration values during both 0-10 m and 10-20 m, regardless of the data filtering technique (p < 0.001). Body mass significantly affected all accelerometer variables (p < 0.10, partial η = 0.091-0.219). Body mass and the absence of a gravity compensation formula affect the accuracy and practicality of accelerometers. Until GPSports-integrated accelerometers incorporate a gravity compensation formula, the usefulness of any accelerometer-derived algorithms is questionable.

  8. TECATE - a code for anisotropic thermoelasticity in high-average-power laser technology. Phase 1 final report

    Energy Technology Data Exchange (ETDEWEB)

    Gelinas, R.J.; Doss, S.K.; Carlson, N.N.

    1985-01-01

    This report describes a totally Eulerian code for anisotropic thermoelasticity (code name TECATE) which may be used in evaluations of prospective crystal media for high-average-power lasers. The present TECATE code version computes steady-state distributions of material temperatures, stresses, strains, and displacement fields in 2-D slab geometry. Numerous heat source and coolant boundary condition options are available in the TECATE code for laser design considerations. Anisotropic analogues of plane stress and plane strain evaluations can be executed for any and all crystal symmetry classes. As with all new and/or large physics codes, it is likely that some code imperfections will emerge at some point in time.

  9. Preparation of high viscosity average molecular mass poly-L-lactide

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhi-hua; RUAN Jian-ming; ZOU Jian-peng; ZHOU Zhong-cheng; SHEN Xiong-jun

    2006-01-01

    Poly-L-lactide(PLLA) was synthesized by ring-opening polymerization from high purity L-lactide with tin octoate as initiator, and characterized by means of infrared, and 1H-nuclear magnetic resonance. The influences of initiator concentration,polymerization temperature and polymerization time on the viscosity average molecular mass of PLLA were investigated. The effects of different purification methods on the concentration of initiator and viscosity average molecular mass were also studied. PLLA with a viscosity average molecular mass of about 50.5×104 was obtained when polymerization was conducted for 24 h at 140 ℃ with the molar ratio of monomer to purification initator being 12 000. After purification, the concentration of tin octoate decreases; however,the effect of different purification methods on the viscosity average molecular mass of PLLA is different, and the obtained PLLA is a typical amorphous polymeric material. The crystallinity of PLLA decreases with the increase of viscosity average molecular mass.

  10. Performance and production requirements for the optical components in a high-average-power laser system

    Energy Technology Data Exchange (ETDEWEB)

    Chow, R.; Doss, F.W.; Taylor, J.R.; Wong, J.N.

    1999-07-02

    Optical components needed for high-average-power lasers, such as those developed for Atomic Vapor Laser Isotope Separation (AVLIS), require high levels of performance and reliability. Over the past two decades, optical component requirements for this purpose have been optimized and performance and reliability have been demonstrated. Many of the optical components that are exposed to the high power laser light affect the quality of the beam as it is transported through the system. The specifications for these optics are described including a few parameters not previously reported and some component manufacturing and testing experience. Key words: High-average-power laser, coating efficiency, absorption, optical components

  11. Radiatively heated high voltage pyroelectric crystal pulser

    Energy Technology Data Exchange (ETDEWEB)

    Antolak, A.J., E-mail: antolak@sandia.gov [Sandia National Laboratories, Livermore, CA 94550 (United States); Chen, A.X. [Sandia National Laboratories, Livermore, CA 94550 (United States); Leung, K.-N. [Sandia National Laboratories, Livermore, CA 94550 (United States); Nuclear Engineering Department, University of California, Berkeley (United States); Morse, D.H.; Raber, T.N. [Sandia National Laboratories, Livermore, CA 94550 (United States)

    2014-01-21

    Thin lithium tantalate pyroelectric crystals in a multi-stage pulser were heated by quartz lamps during their charging phase to generate high voltage pulses. The charging voltage was determined empirically based on the measured breakdown voltage in air and verified by the induced breakdown voltage of an external high voltage power supply. A four-stage pyroelectric crystal device generated pulse discharges of up to 86 kV using both quartz lamps (radiative) and thermoelectric (conductive) heating. Approximately 50 mJ of electrical energy was harvested from the crystals when radiatively heated in air, and up to 720 mJ was produced when the crystals were submerged in a dielectric fluid. It is anticipated that joule-level pulse discharges could be obtained by employing additional stages and optimizing the heating configuration.

  12. High-throughput machining using a high-average power ultrashort pulse laser and high-speed polygon scanner

    Science.gov (United States)

    Schille, Joerg; Schneider, Lutz; Streek, André; Kloetzer, Sascha; Loeschner, Udo

    2016-09-01

    High-throughput ultrashort pulse laser machining is investigated on various industrial grade metals (aluminum, copper, and stainless steel) and Al2O3 ceramic at unprecedented processing speeds. This is achieved by using a high-average power picosecond laser in conjunction with a unique, in-house developed polygon mirror-based biaxial scanning system. Therefore, different concepts of polygon scanners are engineered and tested to find the best architecture for high-speed and precision laser beam scanning. In order to identify the optimum conditions for efficient processing when using high-average laser powers, the depths of cavities made in the samples by varying the processing parameter settings are analyzed and, from the results obtained, the characteristic removal values are specified. For overlapping pulses of optimum fluence, the removal rate is as high as 27.8 mm3/min for aluminum, 21.4 mm3/min for copper, 15.3 mm3/min for stainless steel, and 129.1 mm3/min for Al2O3, when a laser beam of 187 W average laser powers irradiates. On stainless steel, it is demonstrated that the removal rate increases to 23.3 mm3/min when the laser beam is very fast moving. This is thanks to the low pulse overlap as achieved with 800 m/s beam deflection speed; thus, laser beam shielding can be avoided even when irradiating high-repetitive 20-MHz pulses.

  13. Crimes and the Bell Curve: The Role of People with High, Average, and Low Intelligence

    OpenAIRE

    Burhan, Nik Ahmad Sufian; Kurniawan, Yohan; Sidek, Abdul Halim; Mohamad, Mohd Rosli

    2014-01-01

    The present study examines whether crime rates can be reduced by increasing the IQ of people with high, average, and low IQ. Previous studies have shown that as a determinant of the national level of income per capita growth and technological achievement, the IQ of the intellectual class (those at the 95th percentile of the Bell curve distribution of population intelligence) is more important than the IQ of those with average ability at the 50th percentile. Extending these findings, our study...

  14. High pressure ceramic heat exchanger

    Science.gov (United States)

    Harkins, Bruce D.; Ward, Michael E.

    1998-01-01

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present header assembly when used with recuperators reduces the brittle effect of a portion of the ceramic components. Thus, the present header assembly used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present header assembly is comprised of a first ceramic member, a second ceramic member, a strengthening reinforcing member being in spaced relationship to the first ceramic member and the second ceramic member. The header assembly is further comprised of a refractory material disposed in contacting relationship with the first ceramic member, the second ceramic member and the strengthening reinforcing member. The present header assembly provides a high strength load bearing header assembly having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

  15. Reducing Heating In High-Speed Cinematography

    Science.gov (United States)

    Slater, Howard A.

    1989-01-01

    Infrared-absorbing and infrared-reflecting glass filters simple and effective means for reducing rise in temperature during high-speed motion-picture photography. "Hot-mirror" and "cold-mirror" configurations, employed in projection of images, helps prevent excessive heating of scenes by powerful lamps used in high-speed photography.

  16. Spatialization of instantaneous and daily average net radiation and soil heat flux in the territory of Itaparica, Northeast Brazil

    Science.gov (United States)

    Lopes, Helio L.; Silva, Bernardo B.; Teixeira, Antônio H. C.; Accioly, Luciano J. O.

    2012-09-01

    This work has as aim to quantify the energy changes between atmosphere and surface by modeling both net radiation and soil heat flux related to land use and cover. The methodology took into account modeling and mapping of physical and biophysical parameters using MODIS images and SEBAL algorithm in an area of native vegetation and irrigated crops. The results showed that there are variations in the values of the estimated parameters for different land cover types and mainly in caatinga cover. The dense caatinga presents mean values of soil heat flux (Go) of 124.9 Wm-2 while sparse caatinga with incidence of erosion, present average value of 132.6 Wm-2. For irrigated plots cultivated with banana, coconut, and papaya the mean Go values were 103.8, 98.6, 113.9 Wm-2, respectively. With regard to the instantaneous net radiation (Rn), dense caatinga presented mean value of 626.1 Wm-2, while sparse caatinga a mean value of 575.2 Wm-2. Irrigated areas cultivated with banana, coconut, and papaya presented Rn of 658.1, 647.4 and 617.9 W m-2 respectively. Applying daily mean net radiation (RnDAve) it was found that dense caatinga had a mean value of 417.1 W m-2, while sparse caatinga had a mean value of 379.9 W m-2. For the irrigated crops of banana, coconut and papaya the RnDAve values were 430.9, 431.3 and 411.6 W m-2, respectively. Sinusoidal model can be applied to determine the maximum and RnDAve considering the diverse classes of LULC; however, there is a need to compare the results with field data for validation of this model.

  17. Development of a high average current polarized electron source with long cathode operational lifetime

    Energy Technology Data Exchange (ETDEWEB)

    C. K. Sinclair; P. A. Adderley; B. M. Dunham; J. C. Hansknecht; P. Hartmann; M. Poelker; J. S. Price; P. M. Rutt; W. J. Schneider; M. Steigerwald

    2007-02-01

    Substantially more than half of the electromagnetic nuclear physics experiments conducted at the Continuous Electron Beam Accelerator Facility of the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory) require highly polarized electron beams, often at high average current. Spin-polarized electrons are produced by photoemission from various GaAs-based semiconductor photocathodes, using circularly polarized laser light with photon energy slightly larger than the semiconductor band gap. The photocathodes are prepared by activation of the clean semiconductor surface to negative electron affinity using cesium and oxidation. Historically, in many laboratories worldwide, these photocathodes have had short operational lifetimes at high average current, and have often deteriorated fairly quickly in ultrahigh vacuum even without electron beam delivery. At Jefferson Lab, we have developed a polarized electron source in which the photocathodes degrade exceptionally slowly without electron emission, and in which ion back bombardment is the predominant mechanism limiting the operational lifetime of the cathodes during electron emission. We have reproducibly obtained cathode 1/e dark lifetimes over two years, and 1/e charge density and charge lifetimes during electron beam delivery of over 2?105???C/cm2 and 200 C, respectively. This source is able to support uninterrupted high average current polarized beam delivery to three experimental halls simultaneously for many months at a time. Many of the techniques we report here are directly applicable to the development of GaAs photoemission electron guns to deliver high average current, high brightness unpolarized beams.

  18. High-Average-Power Diffraction Pulse-Compression Gratings Enabling Next-Generation Ultrafast Laser Systems

    Energy Technology Data Exchange (ETDEWEB)

    Alessi, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-11-01

    Pulse compressors for ultrafast lasers have been identified as a technology gap in the push towards high peak power systems with high average powers for industrial and scientific applications. Gratings for ultrashort (sub-150fs) pulse compressors are metallic and can absorb a significant percentage of laser energy resulting in up to 40% loss as well as thermal issues which degrade on-target performance. We have developed a next generation gold grating technology which we have scaled to the petawatt-size. This resulted in improvements in efficiency, uniformity and processing as compared to previous substrate etched gratings for high average power. This new design has a deposited dielectric material for the grating ridge rather than etching directly into the glass substrate. It has been observed that average powers as low as 1W in a compressor can cause distortions in the on-target beam. We have developed and tested a method of actively cooling diffraction gratings which, in the case of gold gratings, can support a petawatt peak power laser with up to 600W average power. We demonstrated thermo-mechanical modeling of a grating in its use environment and benchmarked with experimental measurement. Multilayer dielectric (MLD) gratings are not yet used for these high peak power, ultrashort pulse durations due to their design challenges. We have designed and fabricated broad bandwidth, low dispersion MLD gratings suitable for delivering 30 fs pulses at high average power. This new grating design requires the use of a novel Out Of Plane (OOP) compressor, which we have modeled, designed, built and tested. This prototype compressor yielded a transmission of 90% for a pulse with 45 nm bandwidth, and free of spatial and angular chirp. In order to evaluate gratings and compressors built in this project we have commissioned a joule-class ultrafast Ti:Sapphire laser system. Combining the grating cooling and MLD technologies developed here could enable petawatt laser systems to

  19. Free-space optical communications with peak and average constraints: High SNR capacity approximation

    KAUST Repository

    Chaaban, Anas

    2015-09-07

    The capacity of the intensity-modulation direct-detection (IM-DD) free-space optical channel with both average and peak intensity constraints is studied. A new capacity lower bound is derived by using a truncated-Gaussian input distribution. Numerical evaluation shows that this capacity lower bound is nearly tight at high signal-to-noise ratio (SNR), while it is shown analytically that the gap to capacity upper bounds is a small constant at high SNR. In particular, the gap to the high-SNR asymptotic capacity of the channel under either a peak or an average constraint is small. This leads to a simple approximation of the high SNR capacity. Additionally, a new capacity upper bound is derived using sphere-packing arguments. This bound is tight at high SNR for a channel with a dominant peak constraint.

  20. Problem-Solving Processes of High and Average Performers in Physics.

    Science.gov (United States)

    Coleman, Elaine B.; Shore, Bruce

    1991-01-01

    This study examined the problem-solving protocols of 21 students in a grade 11 enriched physics course as well as 3 adult "experts" in physics. Experts and high performing students made more correct metastatements and more references to prior knowledge than did average performing students. (DB)

  1. Total Quality Management (TQM) Practices and School Climate amongst High, Average and Low Performance Secondary Schools

    Science.gov (United States)

    Ismail, Siti Noor

    2014-01-01

    Purpose: This study attempted to determine whether the dimensions of TQM practices are predictors of school climate. It aimed to identify the level of TQM practices and school climate in three different categories of schools, namely high, average and low performance schools. The study also sought to examine which dimensions of TQM practices…

  2. Industrial Heat Pump for a High Temperature District Heating Application

    DEFF Research Database (Denmark)

    Poulsen, Claus Nørgaard

    2013-01-01

    by excess thermal energy from thermal solar panels. An industrial heat pump system using the natural refrigerant ammonia, is extracting the thermal energy from the storage when needed, and produce hot water at 85°C, for the district heating grid. The heat pump also acts as contributor to electricity grid...

  3. High-frequency averaging in semi-classical Hartree-type equations

    CERN Document Server

    Giannoulis, Johannes; Sparber, Christof

    2009-01-01

    We investigate the asymptotic behavior of solutions to semi-classical Schroedinger equations with nonlinearities of Hartree type. For a weakly nonlinear scaling, we show the validity of an asymptotic superposition principle for slowly modulated highly oscillatory pulses. The result is based on a high-frequency averaging effect due to the nonlocal nature of the Hartree potential, which inhibits the creation of new resonant waves. In the proof we make use of the framework of Wiener algebras.

  4. Ionospheric modifications in high frequency heating experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, Spencer P. [Department of Electrical and Computer Engineering, Polytechnic School of Engineering, New York University, 5 MetroTech Center, Brooklyn, New York 11201 (United States)

    2015-01-15

    Featured observations in high-frequency (HF) heating experiments conducted at Arecibo, EISCAT, and high frequency active auroral research program are discussed. These phenomena appearing in the F region of the ionosphere include high-frequency heater enhanced plasma lines, airglow enhancement, energetic electron flux, artificial ionization layers, artificial spread-F, ionization enhancement, artificial cusp, wideband absorption, short-scale (meters) density irregularities, and stimulated electromagnetic emissions, which were observed when the O-mode HF heater waves with frequencies below foF2 were applied. The implication and associated physical mechanism of each observation are discussed and explained. It is shown that these phenomena caused by the HF heating are all ascribed directly or indirectly to the excitation of parametric instabilities which instigate anomalous heating. Formulation and analysis of parametric instabilities are presented. The results show that oscillating two stream instability and parametric decay instability can be excited by the O-mode HF heater waves, transmitted from all three heating facilities, in the regions near the HF reflection height and near the upper hybrid resonance layer. The excited Langmuir waves, upper hybrid waves, ion acoustic waves, lower hybrid waves, and field-aligned density irregularities set off subsequent wave-wave and wave-electron interactions, giving rise to the observed phenomena.

  5. High temperature absorption compression heat pump for industrial waste heat

    DEFF Research Database (Denmark)

    Reinholdt, Lars; Horntvedt, B.; Nordtvedt, S. R.

    2016-01-01

    Heat pumps are currently receiving extensive interest because they may be able to support the integration of large shares of fluctuating electricity production based on renewable sources, and they have the potential for the utilization of low temperature waste heat from industry. In most industries......, the needed temperature levels often range from 100°C and up, but until now, it has been quite difficult to find heat pump technologies that reach this level, and thereby opening up the large-scale heat recovery in the industry. Absorption compression heat pumps can reach temperatures above 100°C......, and they have proved themselves a very efficient and reliable technology for applications that have large temperature changes on the heat sink and/or heat source. The concept of Carnot and Lorenz efficiency and its use in the analysis of system integration is shown. A 1.25 MW system having a Carnot efficiency...

  6. Method for optical pumping of thin laser media at high average power

    Energy Technology Data Exchange (ETDEWEB)

    Zapata, Luis E. (Livermore, CA); Beach, Raymond J. (Livermore, CA); Honea, Eric C. (Sunol, CA); Payne, Stephen A. (Castro Valley, CA)

    2004-07-13

    A thin, planar laser material is bonded to a light guide of an index-matched material forming a composite disk. Diode array or other pump light is introduced into the composite disk through the edges of the disk. Pump light trapped within the composite disk depletes as it multi-passes the laser medium before reaching an opposing edge of the disk. The resulting compound optical structure efficiently delivers concentrated pump light and to a laser medium of minimum thickness. The external face of the laser medium is used for cooling. A high performance cooler attached to the external face of the laser medium rejects heat. Laser beam extraction is parallel to the heat flux to minimize optical distortions.

  7. Development of a high average current polarized electron source with long cathode operational lifetime

    Directory of Open Access Journals (Sweden)

    C. K. Sinclair

    2007-02-01

    Full Text Available Substantially more than half of the electromagnetic nuclear physics experiments conducted at the Continuous Electron Beam Accelerator Facility of the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory require highly polarized electron beams, often at high average current. Spin-polarized electrons are produced by photoemission from various GaAs-based semiconductor photocathodes, using circularly polarized laser light with photon energy slightly larger than the semiconductor band gap. The photocathodes are prepared by activation of the clean semiconductor surface to negative electron affinity using cesium and oxidation. Historically, in many laboratories worldwide, these photocathodes have had short operational lifetimes at high average current, and have often deteriorated fairly quickly in ultrahigh vacuum even without electron beam delivery. At Jefferson Lab, we have developed a polarized electron source in which the photocathodes degrade exceptionally slowly without electron emission, and in which ion back bombardment is the predominant mechanism limiting the operational lifetime of the cathodes during electron emission. We have reproducibly obtained cathode 1/e dark lifetimes over two years, and 1/e charge density and charge lifetimes during electron beam delivery of over 2×10^{5}   C/cm^{2} and 200 C, respectively. This source is able to support uninterrupted high average current polarized beam delivery to three experimental halls simultaneously for many months at a time. Many of the techniques we report here are directly applicable to the development of GaAs photoemission electron guns to deliver high average current, high brightness unpolarized beams.

  8. Hybrid Heat Pipes for High Heat Flux Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The thermal transport requirements for future spacecraft missions continue to increase, approaching several kilowatts. At the same time the heat acquisition areas...

  9. Kilowatt high average power narrow-linewidth nanosecond all-fiber laser

    Institute of Scientific and Technical Information of China (English)

    Rongtao; Su; Pu; Zhou; Xiaolin; Wang; Rumao; Tao; Xiaojun; Xu

    2014-01-01

    A high power narrow-linewidth nanosecond all-fiber laser based on the master oscillator power amplifier(MOPA)configuration is demonstrated. A pulsed seed with high repetition rate of 10 MHz was generated by modulating a continuous-wave(CW) single-frequency fiber laser at ~1064 nm by using an electro-optic intensity modulator(EOIM).After multi-stage cascaded power amplification, the average power was boosted to be kilowatt level. The pulses from the main amplifier had a pulse width of ~3 ns and an average/peak power of 913 W/28.6 kW. Further power scaling of the pulses was limited by stimulated Raman scattering(SRS) for the moment, method for SRS suppression and further power scaling was briefly discussed.

  10. Temperature-insensitive frequency tripling for generating high-average power UV lasers.

    Science.gov (United States)

    Zhong, Haizhe; Yuan, Peng; Wen, Shuangchun; Qian, Liejia

    2014-02-24

    Aimed for generating high-average power ultraviolet (UV) lasers via third-harmonic generation (THG) consisting of frequency doubling and tripling stages, we numerically and experimentally demonstrate a novel frequency tripling scheme capable of supporting temperature-insensitive phase-matching (PM). Two cascaded tripling crystals, with opposite signs of the temperature derivation of phase-mismatch, are proposed and theoretically studied for improving the temperature-acceptance of PM. The proof-of-principle tripling experiment using two crystals of LBO and BBO shows that the temperature acceptance can be ~1.5 times larger than that of using a single tripling crystal. In addition, the phase shift caused by air dispersion, along with its influence on the temperature-insensitive PM, are also discussed. To illustrate the potential applications of proposed two-crystal tripling design in the high-average-power regime, full numerical simulations for the tripling process, are implemented based on the realistic crystals. The demonstrated two-crystal tripling scheme may provide a promising route to high-average-power THG in the UV region.

  11. High energy, high average power solid state green or UV laser

    Science.gov (United States)

    Hackel, Lloyd A.; Norton, Mary; Dane, C. Brent

    2004-03-02

    A system for producing a green or UV output beam for illuminating a large area with relatively high beam fluence. A Nd:glass laser produces a near-infrared output by means of an oscillator that generates a high quality but low power output and then multi-pass through and amplification in a zig-zag slab amplifier and wavefront correction in a phase conjugator at the midway point of the multi-pass amplification. The green or UV output is generated by means of conversion crystals that follow final propagation through the zig-zag slab amplifier.

  12. Global anthropogenic heat flux database with high spatial resolution

    Science.gov (United States)

    Dong, Y.; Varquez, A. C. G.; Kanda, M.

    2017-02-01

    This study developed a top-down method for estimating global anthropogenic heat emission (AHE), with a high spatial resolution of 30 arc-seconds and temporal resolution of 1 h. Annual average AHE was derived from human metabolic heating and primary energy consumption, which was further divided into three components based on consumer sector. The first and second components were heat loss and heat emissions from industrial sectors equally distributed throughout the country and populated areas, respectively. The third component comprised the sum of emissions from commercial, residential, and transportation sectors (CRT). Bulk AHE from the CRT was proportionally distributed using a global population dataset, with a radiance-calibrated nighttime lights adjustment. An empirical function to estimate monthly fluctuations of AHE based on gridded monthly temperatures was derived from various Japanese and American city measurements. Finally, an AHE database with a global coverage was constructed for the year 2013. Comparisons between our proposed AHE and other existing datasets revealed that the problem of overestimation of AHE intensity in previous top-down models was mitigated by the separation of energy consumption sectors; furthermore, the problem of AHE underestimation at central urban areas was solved by the nighttime lights adjustment. A strong agreement in the monthly profiles of AHE between our database and other bottom-up datasets further proved the validity of the current methodology. Investigations of AHE for the 29 largest urban agglomerations globally highlighted that the share of heat emissions from CRT sectors to the total AHE at the city level was 40-95%; whereas that of metabolic heating varied with the city's level of development by a range of 2-60%. A negative correlation between gross domestic product (GDP) and the share of metabolic heating to a city's total AHE was found. Globally, peak AHE values were found to occur between December and February, while

  13. High average power picosecond pulse generation from a thulium-doped all-fiber MOPA system.

    Science.gov (United States)

    Liu, Jiang; Wang, Qian; Wang, Pu

    2012-09-24

    We report a stable highly-integrated high power picosecond thulium-doped all-fiber MOPA system without using conventional chirped pulse amplification technique. The master oscillator was passively mode-locked by a SESAM to generate average power of 15 mW at a fundamental repetition rate of 103 MHz in a short linear cavity, and a uniform narrow bandwidth FBG is employed to stabilize the passively mode-locked laser operation. Two-stage double-clad thulium-doped all-fiber amplifiers were used directly to boost average power to 20.7 W. The laser center wavelength was 1962.8 nm and the pulse width was 18 ps. The single pulse energy and peak-power after the amplication were 200 nJ and 11.2 kW respectively. To the best of our knowledge, this is the highest average power ever reported for a picosecond thulium-doped all-fiber MOPA system.

  14. Stagnation Region Heat Transfer Augmentation at Very High Turbulence Levels

    Energy Technology Data Exchange (ETDEWEB)

    Ames, Forrest [University of North Dakota; Kingery, Joseph E. [University of North Dakota

    2015-06-17

    A database for stagnation region heat transfer has been extended to include heat transfer measurements acquired downstream from a new high intensity turbulence generator. This work was motivated by gas turbine industry heat transfer designers who deal with heat transfer environments with increasing Reynolds numbers and very high turbulence levels. The new mock aero-combustor turbulence generator produces turbulence levels which average 17.4%, which is 37% higher than the older turbulence generator. The increased level of turbulence is caused by the reduced contraction ratio from the liner to the exit. Heat transfer measurements were acquired on two large cylindrical leading edge test surfaces having a four to one range in leading edge diameter (40.64 cm and 10.16 cm). Gandvarapu and Ames [1] previously acquired heat transfer measurements for six turbulence conditions including three grid conditions, two lower turbulence aero-combustor conditions, and a low turbulence condition. The data are documented and tabulated for an eight to one range in Reynolds numbers for each test surface with Reynolds numbers ranging from 62,500 to 500,000 for the large leading edge and 15,625 to 125,000 for the smaller leading edge. The data show augmentation levels of up to 136% in the stagnation region for the large leading edge. This heat transfer rate is an increase over the previous aero-combustor turbulence generator which had augmentation levels up to 110%. Note, the rate of increase in heat transfer augmentation decreases for the large cylindrical leading edge inferring only a limited level of turbulence intensification in the stagnation region. The smaller cylindrical leading edge shows more consistency with earlier stagnation region heat transfer results correlated on the TRL (Turbulence, Reynolds number, Length scale) parameter. The downstream regions of both test surfaces continue to accelerate the flow but at a much lower rate than the leading edge. Bypass transition occurs

  15. High-average-power 2 μm few-cycle optical parametric chirped pulse amplifier at 100 kHz repetition rate.

    Science.gov (United States)

    Shamir, Yariv; Rothhardt, Jan; Hädrich, Steffen; Demmler, Stefan; Tschernajew, Maxim; Limpert, Jens; Tünnermann, Andreas

    2015-12-01

    Sources of long wavelengths few-cycle high repetition rate pulses are becoming increasingly important for a plethora of applications, e.g., in high-field physics. Here, we report on the realization of a tunable optical parametric chirped pulse amplifier at 100 kHz repetition rate. At a central wavelength of 2 μm, the system delivered 33 fs pulses and a 6 W average power corresponding to 60 μJ pulse energy with gigawatt-level peak powers. Idler absorption and its crystal heating is experimentally investigated for a BBO. Strategies for further power scaling to several tens of watts of average power are discussed.

  16. Incidence Rates of Clinical Mastitis among Canadian Holsteins Classified as High, Average, or Low Immune Responders

    Science.gov (United States)

    Miglior, Filippo; Mallard, Bonnie A.

    2013-01-01

    The objective of this study was to compare the incidence rate of clinical mastitis (IRCM) between cows classified as high, average, or low for antibody-mediated immune responses (AMIR) and cell-mediated immune responses (CMIR). In collaboration with the Canadian Bovine Mastitis Research Network, 458 lactating Holsteins from 41 herds were immunized with a type 1 and a type 2 test antigen to stimulate adaptive immune responses. A delayed-type hypersensitivity test to the type 1 test antigen was used as an indicator of CMIR, and serum antibody of the IgG1 isotype to the type 2 test antigen was used for AMIR determination. By using estimated breeding values for these traits, cows were classified as high, average, or low responders. The IRCM was calculated as the number of cases of mastitis experienced over the total time at risk throughout the 2-year study period. High-AMIR cows had an IRCM of 17.1 cases per 100 cow-years, which was significantly lower than average and low responders, with 27.9 and 30.7 cases per 100 cow-years, respectively. Low-AMIR cows tended to have the most severe mastitis. No differences in the IRCM were noted when cows were classified based on CMIR, likely due to the extracellular nature of mastitis-causing pathogens. The results of this study demonstrate the desirability of breeding dairy cattle for enhanced immune responses to decrease the incidence and severity of mastitis in the Canadian dairy industry. PMID:23175290

  17. Low temperature heating and high temperature cooling embedded water based surface heating and cooling systems

    CERN Document Server

    Babiak, Jan; Petras, Dusan

    2009-01-01

    This Guidebook describes the systems that use water as heat-carrier and when the heat exchange within the conditioned space is more than 50% radiant. Embedded systems insulated from the main building structure (floor, wall and ceiling) are used in all types of buildings and work with heat carriers at low temperatures for heating and relatively high temperature for cooling.

  18. New generation of high average power industry grade ultrafast ytterbium fiber lasers

    Science.gov (United States)

    Yusim, Alex; Samartsev, Igor; Shkurikhin, Oleg; Myasnikov, Daniil; Bordenyuk, Andrey; Platonov, Nikolai; Kancharla, Vijay; Gapontsev, Valentin

    2016-03-01

    We report an industrial grade picosecond and femtosecond pulse Yb fiber lasers with >100 μJ pulse energy and hundreds of Watts of average power for improved laser machining speed of sapphire and glass. This highly efficient laser offers >25% wall plug efficiency within a compact 3U rack-mountable configuration plus a long >2m fiber delivery cable. Reconfigurable features such as controllable repetition rate, fine pulse duration control, burst mode operation and adjustable pulse energy permit the customer to tailor the laser to their application.

  19. Dual-scale turbulence in filamenting laser beams at high average power

    CERN Document Server

    Schubert, Elise; Mongin, Denis; Kasparian, Jérôme; Wolf, Jean-Pierre; Klingebiel, Sandro; Schultze, Marcel; Metzger, Thomas; Michel, Knut

    2016-01-01

    We investigate the self-induced turbulence of high repetition rate laser filaments over a wide range of average powers (1 mW to 100 W) and its sensitivity to external atmospheric turbulence. Although both externally-imposed and self-generated turbulences can have comparable magnitudes, they act on different temporal and spatial scales. While the former drives the shot-to-shot motion at the millisecond time scale, the latter acts on the 0.5 s scale. As a consequence, their effects are decoupled, preventing beam stabilization by the thermally-induced low-density channel produced by the laser filaments.

  20. Electronically controlled heat sink for high-power laser diodes

    Science.gov (United States)

    Vetrovec, John

    2009-05-01

    We report on a novel electronically controlled active heat sink for high-power laser diodes offering unparalleled capacity in high-heat flux handling and temperature control. The heat sink receives diode waste heat at high flux and transfers it at reduced flux to environment, coolant fluid, heat pipe, or structure. Thermal conductance of the heat sink is electronically adjustable, allowing for precise control of diode temperature and the diode light wavelength. When pumping solid-state or alkaline vapor lasers, diode wavelength can be precisely temperature-tuned to the gain medium absorption features. This paper presents the heat sink physics, engineering design, and performance modeling.

  1. Is sexual reproduction of high-mountain plants endangered by heat?

    Science.gov (United States)

    Ladinig, Ursula; Pramsohler, Manuel; Bauer, Ines; Zimmermann, Sonja; Neuner, Gilbert; Wagner, Johanna

    2015-04-01

    Strong solar irradiation in combination with still air and dry soil can cause prostrate high-mountain plants to heat up considerably and ultimately suffer heat damage. Such heat damage has been repeatedly shown for vegetative structures, but not for reproductive structures, which we expected to be particularly vulnerable to heat. Heat effects on cold-adapted plants may increase with rising global temperatures and the predicted increase in heat waves. We have tested the heat tolerance of reproductive versus vegetative shoots at different reproductive stages, comparing ten common plant species from different elevation belts in the European Alps. Plant samples were exposed to temperatures in 2-K steps of 30 min each between 42 and 56 °C. Heat damage was assessed by visual rating and vital staining. Reproductive shoots were on average 2.5 K less heat tolerant (LT50, i.e. the mean temperature causing 50 % heat damage, 47.2 °C) than vegetative shoots (mean LT50 49.7 °C). Initial heat injuries (mean LT10) were observed at 43-45 °C in heat-susceptible species and at 45-47 °C in more heat-tolerant species, in at least one reproductive stage. Generally, heat tolerance was significantly higher during fruiting than during the bud stages and anthesis. Prostrate species with acaulescent buds and flowers tolerated heat better than those with caulescent buds and flowers. Petals were the most heat-susceptible plant structure and mature pollen the most heat tolerant. Based on these data, heat tolerance of reproductive structures appears to be adapted to the prevailing maximum temperatures which the plants experience during different reproductive stages in their environment. During hot spells, however, heat tolerance thresholds may be exceeded. More frequent heat waves would decrease the reproductive output and, consequently, the competitiveness of heat-susceptible species.

  2. Commercial Integrated Heat Pump with Thermal Storage --Demonstrate Greater than 50% Average Annual Energy Savings, Compared with Baseline Heat Pump and Water Heater (Go/No-Go) FY16 4th Quarter Milestone Report

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Bo [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Baxter, Van D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Rice, C. Keith [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Abu-Heiba, Ahmad [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-03-01

    For this study, we authored a new air source integrated heat pump (AS-IHP) model in EnergyPlus, and conducted building energy simulations to demonstrate greater than 50% average energy savings, in comparison to a baseline heat pump with electric water heater, over 10 US cities, based on the EnergyPlus quick-service restaurant template building. We also assessed water heating energy saving potentials using ASIHP versus gas heating, and pointed out climate zones where AS-IHPs are promising.

  3. Sensitivity of Large-Aperture Scintillometer Measurements of Area-Average Heat Fluxes to Uncertainties in Topographic Heights

    CERN Document Server

    Gruber, Matthew A; Hartogensis, Oscar K

    2013-01-01

    Scintillometers measure $C_n^2$ over large areas of turbulence in the atmospheric surface layer. Turbulent fluxes of heat and momentum are inferred through coupled sets of equations derived from the Monin-Obukhov similarity hypothesis. One-dimensional sensitivity functions have been produced which relate the sensitivity of heat fluxes to uncertainties in single values of beam height over homogeneous and flat terrain. Real field sites include variable topography and heterogeneous surface properties such as roughness length. We develop here the first analysis of the sensitivity of scintillometer derived sensible heat fluxes to uncertainties in spacially distributed topographic measurements. For large-aperture scintillometers and independent $u_\\star$ measurements, sensitivity is shown to be concentrated in areas near the center of the beam and where the underlying topography is closest to the beam height. Uncertainty may be greatly reduced by focusing precise topographic measurements in these areas. The new two...

  4. Development and significance of a fetal electrocardiogram recorded by signal-averaged high-amplification electrocardiography.

    Science.gov (United States)

    Hayashi, Risa; Nakai, Kenji; Fukushima, Akimune; Itoh, Manabu; Sugiyama, Toru

    2009-03-01

    Although ultrasonic diagnostic imaging and fetal heart monitors have undergone great technological improvements, the development and use of fetal electrocardiograms to evaluate fetal arrhythmias and autonomic nervous activity have not been fully established. We verified the clinical significance of the novel signal-averaged vector-projected high amplification ECG (SAVP-ECG) method in fetuses from 48 gravidas at 32-41 weeks of gestation and in 34 neonates. SAVP-ECGs from fetuses and newborns were recorded using a modified XYZ-leads system. Once noise and maternal QRS waves were removed, the P, QRS, and T wave intervals were measured from the signal-averaged fetal ECGs. We also compared fetal and neonatal heart rates (HRs), coefficients of variation of heart rate variability (CV) as a parasympathetic nervous activity, and the ratio of low to high frequency (LF/HF ratio) as a sympathetic nervous activity. The rate of detection of a fetal ECG by SAVP-ECG was 72.9%, and the fetal and neonatal QRS and QTc intervals were not significantly different. The neonatal CVs and LF/HF ratios were significantly increased compared with those in the fetus. In conclusion, we have developed a fetal ECG recording method using the SAVP-ECG system, which we used to evaluate autonomic nervous system development.

  5. Status of HiLASE project: High average power pulsed DPSSL systems for research and industry

    Directory of Open Access Journals (Sweden)

    Mocek T.

    2013-11-01

    Full Text Available We introduce the Czech national R&D project HiLASE which focuses on strategic development of advanced high-repetition rate, diode pumped solid state laser (DPSSL systems that may find use in research, high-tech industry and in the future European large-scale facilities such as HiPER and ELI. Within HiLASE we explore two major concepts: thin-disk and cryogenically cooled multislab amplifiers capable of delivering average output powers above 1 kW level in picosecond-to-nanosecond pulsed regime. In particular, we have started a programme of technology development to demonstrate the scalability of multislab concept up to the kJ level at repetition rate of 1–10 Hz.

  6. Status of HiLASE project: High average power pulsed DPSSL systems for research and industry

    Science.gov (United States)

    Mocek, T.; Divoky, M.; Smrz, M.; Sawicka, M.; Chyla, M.; Sikocinski, P.; Vohnikova, H.; Severova, P.; Lucianetti, A.; Novak, J.; Rus, B.

    2013-11-01

    We introduce the Czech national R&D project HiLASE which focuses on strategic development of advanced high-repetition rate, diode pumped solid state laser (DPSSL) systems that may find use in research, high-tech industry and in the future European large-scale facilities such as HiPER and ELI. Within HiLASE we explore two major concepts: thin-disk and cryogenically cooled multislab amplifiers capable of delivering average output powers above 1 kW level in picosecond-to-nanosecond pulsed regime. In particular, we have started a programme of technology development to demonstrate the scalability of multislab concept up to the kJ level at repetition rate of 1-10 Hz.

  7. High average power CO II laser MOPA system for Tin target LPP EUV light source

    Science.gov (United States)

    Ariga, Tatsuya; Hoshino, Hideo; Endo, Akira

    2007-02-01

    Extreme ultraviolet lithography (EUVL) is the candidate for next generation lithography to be introduced by the semiconductor industry to HVM (high volume manufacturing) in 2013. The power of the EUVL light source has to be at least 115W at a wavelength of 13.5nm. A laser produced plasma (LPP) is the main candidate for this light source but a cost effective laser driver is the key requirement for the realization of this concept. We are currently developing a high power and high repetition rate CO II laser system to achieve 50 W intermediate focus EUV power with a Tin droplet target. We have achieved CE of 2.8% with solid Tin wire target by a transversely excited atmospheric (TEA) CO II laser MOPA system with pulse width, pulse energy and pulse repetition rate as 10~15 ns, 30 mJ and 10 Hz, respectively. A CO II laser system with a short pulse length less than 15 ns, a nominal average power of a few kW, and a repetition rate of 100 kHz, based on RF-excited, fast axial flow CO II laser amplifiers is under development. Output power of about 3 kW has been achieved with a pulse length of 15 ns at 130 kHz repletion rate in a small signal amplification condition with P(20) single line. The phase distortion of the laser beam after amplification is negligible and the beam can be focused to about 150μm diameter in 1/e2. The CO II laser system is reported on short pulse amplification performance using RF-excited fast axial flow lasers as amplifiers. And the CO II laser average output power scaling is shown towards 5~10 kW with pulse width of 15 ns from a MOPA system.

  8. Average Anisotropy Characteristics of High Energy Cosmic Ray Particles and Geomagnetic Disturbance Index Ap

    Indian Academy of Sciences (India)

    C. M. Tiwari; D. P. Tiwari; Ajay K. Pandey; Pankaj K. Shrivastava

    2005-12-01

    The average characteristics of the diurnal and semi-diurnal anisotropy of cosmic ray intensity at relativistic energies have been obtained by using data from the worldwide grid of neutron monitor for the period 1989 to 1996. The complex behaviour of the diurnal amplitudes and time of maxima (phase) and its association with the Ap index on a long-term and day-to-day basis have been studied. Even though the general characteristics, on a yearly average basis, have not changed significantly during this period, both the diurnal and semi-diurnal amplitudes and phases vary significantly, besides significant changes being observed for different interplanetary conditions on a short-term basis. It is found that the relationship between the Ap index and the diurnal vector is out of phase during the period 1991 to 1995. On a long-term basis, the correlation of diurnal variation with Ap index has been found to vary during the solar cycle. On a short-term basis, it has been observed that the high Ap days are usually associated with higher amplitudes with phase shifted to earlier hours.

  9. A high-sensitivity 2x2 multi-aperture color camera based on selective averaging

    Science.gov (United States)

    Zhang, Bo; Kagawa, Keiichiro; Takasawa, Taishi; Seo, Min-Woong; Yasutomi, Keita; Kawahito, Shoji

    2015-03-01

    To demonstrate the low-noise performance of the multi-aperture imaging system using a selective averaging method, an ultra-high-sensitivity multi-aperture color camera with 2×2 apertures is being developed. In low-light conditions, random telegraph signal (RTS) noise and dark current white defects become visible, which greatly degrades the quality of the image. To reduce these kinds of noise as well as to increase the number of incident photons, the multi-aperture imaging system composed of an array of lens and CMOS image sensor (CIS), and the selective averaging for minimizing the synthetic sensor noise at every pixel is utilized. It is verified by simulation that the effective noise at the peak of noise histogram is reduced from 1.44 e- to 0.73 e- in a 2×2-aperture system, where RTS noise and dark current white defects have been successfully removed. In this work, a prototype based on low-noise color sensors with 1280×1024 pixels fabricated in 0.18um CIS technology is considered. The pixel pitch is 7.1μm×7.1μm. The noise of the sensor is around 1e- based on the folding-integration and cyclic column ADCs, and the low voltage differential signaling (LVDS) is used to improve the noise immunity. The synthetic F-number of the prototype is 0.6.

  10. Comparison of the high temperature heat flux sensor to traditional heat flux gages under high heat flux conditions.

    Energy Technology Data Exchange (ETDEWEB)

    Blanchat, Thomas K.; Hanks, Charles R.

    2013-04-01

    Four types of heat flux gages (Gardon, Schmidt-Boelter, Directional Flame Temperature, and High Temperature Heat Flux Sensor) were assessed and compared under flux conditions ranging between 100-1000 kW/m2, such as those seen in hydrocarbon fire or propellant fire conditions. Short duration step and pulse boundary conditions were imposed using a six-panel cylindrical array of high-temperature tungsten lamps. Overall, agreement between all gages was acceptable for the pulse tests and also for the step tests. However, repeated tests with the HTHFS with relatively long durations at temperatures approaching 1000ÀC showed a substantial decrease (10-25%) in heat flux subsequent to the initial test, likely due to the mounting technique. New HTHFS gages have been ordered to allow additional tests to determine the cause of the flux reduction.

  11. Analysis of heat transfer of loop heat pipe used to cool high power LED

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A novel loop heat pipe(LHP)cooling device for high power LED is developed.The thermal capabilities, including startup performance,temperature uniformity and thermal resistance of the loop heat pipe under different heat loads and incline angles have been investigated experimentally.The obtained results indicate that the thermal resistance of the heat pipe heat sink is in the range of 0.19―3.1 K/W,the temperature uniformity in the evaporator is controlled within 1.5℃,and the junction temperature of high power LED can be controlled steadily under 100℃for a heat load of 100 W.

  12. Sensitivity of large-aperture scintillometer measurements of area-average heat fluxes to uncertainties in topographic heights

    Directory of Open Access Journals (Sweden)

    M. A. Gruber

    2014-01-01

    Full Text Available Scintillometer measurements allow for estimations of the refractive index structure parameter Cn2 over large areas in the atmospheric surface layer. Turbulent fluxes of heat and momentum are inferred through coupled sets of equations derived from the Monin–Obukhov similarity hypothesis. One-dimensional sensitivity functions have been produced that relate the sensitivity of heat fluxes to uncertainties in single values of beam height over homogeneous and flat terrain. However, real field sites include variable topography and heterogeneous surfaces. We develop here the first analysis of the sensitivity of scintillometer derived sensible heat fluxes to uncertainties in spatially distributed topographic measurements. For large-aperture scintillometers and independent friction velocity u* measurements, sensitivity is shown to be concentrated in areas near the center of the beam path and where the underlying topography is closest to the beam height. Uncertainty may be greatly reduced by focusing precise topographic measurements in these areas. A new two-dimensional variable terrain sensitivity function is developed for quantitative error analysis. This function is compared with the previous one-dimensional sensitivity function for the same measurement strategy over flat and homogeneous terrain. Additionally, a new method of solution to the set of coupled equations is produced that eliminates computational error. The results are produced using a new methodology for error analysis involving distributed parameters that may be applied in other disciplines.

  13. Optimisation of high average power optical parametric generation using a photonic crystal fiber.

    Science.gov (United States)

    Sloanes, Trefor; McEwan, Ken; Lowans, Brian; Michaille, Laurent

    2008-11-24

    In this paper the length of a photonic crystal fiber is optimised to perform high average output power parametric generation with maximum efficiency. It is shown that the fiber length has to be increased up to 150 m, well beyond the walk-off distance between the pump and signal/idler, to optimize the generation efficiency. In this regime, the Raman process can take over from four-wave mixing and lead to supercontinuum generation. It is shown that the parametric wavelength conversion is directional; probably due to small variations in the core dimensions along the fiber length. The fiber exhibits up to 40% conversion efficiency, with the idler (0.9 microm) and the signal (1.3 microm) having a combined output power of over 1.5 W.

  14. The Mercury Project: A High Average Power, Gas-Cooled Laser For Inertial Fusion Energy Development

    Energy Technology Data Exchange (ETDEWEB)

    Bayramian, A; Armstrong, P; Ault, E; Beach, R; Bibeau, C; Caird, J; Campbell, R; Chai, B; Dawson, J; Ebbers, C; Erlandson, A; Fei, Y; Freitas, B; Kent, R; Liao, Z; Ladran, T; Menapace, J; Molander, B; Payne, S; Peterson, N; Randles, M; Schaffers, K; Sutton, S; Tassano, J; Telford, S; Utterback, E

    2006-11-03

    Hundred-joule, kilowatt-class lasers based on diode-pumped solid-state technologies, are being developed worldwide for laser-plasma interactions and as prototypes for fusion energy drivers. The goal of the Mercury Laser Project is to develop key technologies within an architectural framework that demonstrates basic building blocks for scaling to larger multi-kilojoule systems for inertial fusion energy (IFE) applications. Mercury has requirements that include: scalability to IFE beamlines, 10 Hz repetition rate, high efficiency, and 10{sup 9} shot reliability. The Mercury laser has operated continuously for several hours at 55 J and 10 Hz with fourteen 4 x 6 cm{sup 2} ytterbium doped strontium fluoroapatite (Yb:S-FAP) amplifier slabs pumped by eight 100 kW diode arrays. The 1047 nm fundamental wavelength was converted to 523 nm at 160 W average power with 73% conversion efficiency using yttrium calcium oxy-borate (YCOB).

  15. On the XFEL Schrödinger Equation: Highly Oscillatory Magnetic Potentials and Time Averaging

    KAUST Repository

    Antonelli, Paolo

    2014-01-14

    We analyse a nonlinear Schrödinger equation for the time-evolution of the wave function of an electron beam, interacting selfconsistently through a Hartree-Fock nonlinearity and through the repulsive Coulomb interaction of an atomic nucleus. The electrons are supposed to move under the action of a time dependent, rapidly periodically oscillating electromagnetic potential. This can be considered a simplified effective single particle model for an X-ray free electron laser. We prove the existence and uniqueness for the Cauchy problem and the convergence of wave-functions to corresponding solutions of a Schrödinger equation with a time-averaged Coulomb potential in the high frequency limit for the oscillations of the electromagnetic potential. © 2014 Springer-Verlag Berlin Heidelberg.

  16. Average Neutron Total Cross Sections in the Unresolved Energy Range From ORELA High Resolutio Transmission Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Derrien, H

    2004-05-27

    Average values of the neutron total cross sections of {sup 233}U, {sup 235}U, {sup 238}U, and {sup 239}Pu have been obtained in the unresolved resonance energy range from high-resolution transmission measurements performed at ORELA in the past two decades. The cross sections were generated by correcting the effective total cross sections for the self-shielding effects due to the resonance structure of the data. The self-shielding factors were found by calculating the effective and true cross sections with the computer code SAMMY for the same Doppler and resolution conditions as for the transmission measurements, using an appropriate set of resonance parameters. Our results are compared to results of previous measurements and to the current ENDF/B-VI data.

  17. Cryogenic nanosecond and picosecond high average and peak power(HAPP) pump lasers for ultrafast applications

    Institute of Scientific and Technical Information of China (English)

    David C.Brown; Sten Tornegrd; Joseph Kolis

    2016-01-01

    Using cryogenic laser technology, it is now possible to design and demonstrate lasers that have concomitant high average and peak powers, with near-diffraction-limited beam quality. We refer to these new laser systems as HAPP lasers. In this paper, we review important laser crystal materials properties at cryogenic temperature, with an emphasis on Yb lasers, and discuss the important design considerations, including the laser-induced damage threshold, nonlinear effects and thermal effects. A comprehensive model is presented to describe diode pulsed pumping with arbitrary duration and repetition rate, and is used with the Frantz–Nodvik equation to describe, to first order, the performance of HAPP laser systems. A computer code with representative results is also described.

  18. Comparative Study of Reynolds Averaged and Embedded Large Eddy Simulations of a High Pressure Turbine Stage

    Science.gov (United States)

    Jones, Sam; Jemcov, Aleksandar; Corke, Thomas

    2016-11-01

    An Embedded Large Eddy Simulation (ELES) approach is used to simulate the flow path through a high pressure turbine stage that includes the entry duct, stationary inlet and exit guide vanes, and a rotor. The flowfield around the rotor is simulated using LES. A Reynolds Averaged Simulation (RAS) is used for the rest of the flow domain. The interface between RAS and LES domains uses the RAS turbulence quantities as a means of obtaining length scales that are used in computing the vorticity required to trigger a proper energy cascade within the LES part of the flow field. The objective is to resolve the unsteady vortical motions that eminate from the gap between the rotor tip and duct walls that are presumably under-resolved in a RAS approach. A comparative analysis between RAS and ELES approaches for this turbomachinery problem is then presented. APS Fellow.

  19. High average power Q-switched 1314 nm two-crystal Nd:YLF laser

    CSIR Research Space (South Africa)

    Botha, RC

    2015-02-01

    Full Text Available . 40, No. 4 / OPTICS LETTERS High average power Q-switched 1314 nm two-crystal Nd:YLF laser R. C. Botha,1,2,* W. Koen,3 M. J. D. Esser,3,4 C. Bollig,3,5 W. L. Combrinck,1,6 H. M. von Bergmann,2 and H. J. Strauss3 1HartRAO, P.O. Box 443..., Krugersdorp, 1740 South Africa 2Stellenbosch University, P/Bag X1, Matieland, 7602 South Africa 3National Laser Centre, CSIR, PO Box 395, Pretoria, 0001 South Africa 4Formerly at CSIR, now at Heriot-Watt University, EH14 4AS Edinburgh, UK 5Formerly at CSIR...

  20. Selling students short: Racial differences in teachers' evaluations of high, average, and low performing students.

    Science.gov (United States)

    Irizarry, Yasmiyn

    2015-07-01

    Education scholars document notable racial differences in teachers' perceptions of students' academic skills. Using data from the Early Childhood Longitudinal Study-Kindergarten Cohort, this study advances research on teacher perceptions by investigating whether racial differences in teachers' evaluations of first grade students' overall literacy skills vary for high, average, and low performing students. Results highlight both the overall accuracy of teachers' perceptions, and the extent and nature of possible inaccuracies, as demonstrated by remaining racial gaps net literacy test performance. Racial differences in teachers' perceptions of Black, non-White Latino, and Asian students (compared to White students) exist net teacher and school characteristics and vary considerably across literacy skill levels. Skill specific literacy assessments appear to explain the remaining racial gap for Asian students, but not for Black and non-White Latino students. Implications of these findings for education scholarship, gifted education, and the achievement gap are discussed.

  1. Efficient Pumping Schemes for High Average Brightness Collisional X-ray Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Keenan, R; Dunn, J; Shlyaptsev, V N; Smith, R F; Patel, P K; Price, D F

    2003-10-07

    Advances in transient collisional x-ray lasers have been demonstrated over the last 5 years as a technique for achieving tabletop soft x-ray lasers using 2-10 J of laser pump energy. The high peak brightness of these sources operating in the high output saturation regime, in the range of 10{sup 24}-10{sup 25} ph. mm{sup -2} mrad{sup -2} s-1 (0.1% BW){sup -1}, is ideal for many applications requiring high photon fluence in a single short burst. However, the pump energy required for these x-ray lasers is still relatively high and limits the x-ray laser repetition rate to 1 shot every few minutes. Higher repetition rate collisional schemes have been reported and show some promise for high output in the future. We report a novel technique for enhancing the coupling efficiency of the laser pump into the gain medium that could lead to enhanced x-ray inversion with a factor of ten reduction in the drive energy. This has been applied to the collisional excitation scheme for Ni-like Mo at 18.9 nm and x-ray laser output has been demonstrated. Preliminary results show lasing on a single shot of the optical laser operating at 10 Hz and with 70 mJ in the short pulse. Such a proposed source would have higher average brightness, {approx}10{sup 14} ph. mm{sup -2} mrad{sup -2} s{sup -1} (0.1% BW){sup -1}, than present bending magnet 3rd generation synchrotron sources operating at the same spectral range.

  2. Intraindividual neuropsychological test variability in healthy individuals with high average intelligence and educational attainment.

    Science.gov (United States)

    Heyanka, Daniel J; Holster, Jessica L; Golden, Charles J

    2013-08-01

    Knowledge of patterns of neuropsychological performance among normal, healthy individuals is integral to the practice of clinical neuropsychology, because clinicians may not always account for intraindividual variability (IIV) before coming to diagnostic conclusions. The IIV was assessed among a sample of 46 healthy individuals with high average intelligence and educational attainment, utilizing a battery of neuropsychological tests, including the Wechsler Adult Intelligence Scale, Fourth Edition (WAIS-IV) and Wechsler Memory Scale, Fourth Edition (WMS-IV). The data indicated substantial variability in neurocognitive abilities. All participants were found to demonstrate scores considered impaired by at least 2 standard deviations (SDs). Despite adjusting for outliers, no participant produced a "normal" testing profile with an intraindividual maximum discrepancy (MD) of less than 1 SD in either direction. When WAIS-IV Full Scale IQ (FSIQ) was considered, participants generally demonstrated cognitive test scores ranging from 2 SDs less than to 1.5 SDs greater than their FSIQ. Furthermore, after demographic corrections, the majority (59%) of participants demonstrated at least 1 impaired cognitive test score, as defined by being 1 to 1.5 SDs below the mean. Overall, results substantiate the need for clinicians to consider FSIQ and educational attainment in interpretation of neuropsychological testing results, given the relevant commonality of "abnormal" test scores within this population. This may ultimately reduce the likelihood of making false-positive conclusions of impairment when educational attainment and intelligence are high, thus improving diagnostic accuracy.

  3. A Comparison of Strategic Development for Multiplication Problem Solving in Low-, Average-, and High-Achieving Students

    Science.gov (United States)

    Zhang, Dake; Ding, Yi; Barrett, Dave E.; Xin, Yan Ping; Liu, Ru-de

    2014-01-01

    The present study investigated the differences of strategy use between low-, average-, and high-achieving students when solving different multiplication problems. Nineteen high-, 48 average-, and 17 low-achieving students participated in this study. All participants were asked to complete three different multiplication tests and to explain how…

  4. Efficient air-water heat pumps for high temperature lift residential heating, including oil migration aspects

    OpenAIRE

    Zehnder, Michele; Favrat, Daniel

    2005-01-01

    This thesis presents a system approach with the aim to develop improved concepts for small capacity, high temperature lift air-water heat pumps. These are intended to replace fuel fired heating systems in the residential sector, which leads to a major reduction of the local greenhouse gas emissions. Unfavorable temperature conditions set by the existing heat distribution systems and by the use of atmospheric air, as the only accessible heat source, have to be overcome. The proposed concepts a...

  5. A study of the motion and aerodynamic heating of ballistic missiles entering the earth's atmosphere at high supersonic speeds

    Science.gov (United States)

    Allen, H Julian; Eggers, A J , Jr

    1958-01-01

    A simplified analysis of the velocity and deceleration history of ballistic missiles entering the earth's atmosphere at high supersonic speeds is presented. The results of this motion analysis are employed to indicate means available to the designer for minimizing aerodynamic heating. The heating problem considered involves not only the total heat transferred to a missile by convection, but also the maximum average and local time rates of convective heat transfer.

  6. Heat transfer capability simulation of high-temperature heat pipe in supersonic vehicle leading edge applications

    Directory of Open Access Journals (Sweden)

    Donghuan Liu

    2016-04-01

    Full Text Available A numerical method is proposed to determine the heat transfer capability of the high-temperature heat pipe and the stagnation temperature with supersonic vehicle leading edge applications. The finite element method is employed here to perform the temperature field simulation. Without considering the heat transfer limitations of the heat pipe, such as capillary limit and sonic limit, both numerical and experimental results indicate that equivalent high thermal conductivity method is a reasonable way to simulate the heat transfer capability of the high-temperature heat pipe in preliminary design of a heat-pipe-cooled leading edge. Several important parameters’ effects on the thermal protection performance are also numerically investigated.

  7. Rapid heating of matter using high power lasers

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Woosuk [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-04-08

    This slide presentation describes motivation (uniform and rapid heating of a target, opportunity to study warm dense matter, study of nuclear fusion reactions), rapid heating of matter with intense laser-driven ion beams, visualization of the expanding warm dense gold and diamond, and nuclear fusion experiments using high power lasers (direct heating of deuterium spheres (radius ~ 10nm) with an intense laser pulse.

  8. A thermosyphon heat pipe cooler for high power LEDs cooling

    Science.gov (United States)

    Li, Ji; Tian, Wenkai; Lv, Lucang

    2016-08-01

    Light emitting diode (LED) cooling is facing the challenge of high heat flux more seriously with the increase of input power and diode density. The proposed unique thermosyphon heat pipe heat sink is particularly suitable for cooling of high power density LED chips and other electronics, which has a heat dissipation potential of up to 280 W within an area of 20 mm × 22 mm (>60 W/cm2) under natural air convection. Meanwhile, a thorough visualization investigation was carried out to explore the two phase flow characteristics in the proposed thermosyphon heat pipe. Implementing this novel thermosyphon heat pipe heat sink in the cooling of a commercial 100 W LED integrated chip, a very low apparent thermal resistance of 0.34 K/W was obtained under natural air convection with the aid of the enhanced boiling heat transfer at the evaporation side and the enhanced natural air convection at the condensation side.

  9. Numerical investigation of fluid flow and heat transfer under high heat flux using rectangular micro-channels

    KAUST Repository

    Mansoor, Mohammad M.

    2012-02-01

    A 3D-conjugate numerical investigation was conducted to predict heat transfer characteristics in a rectangular cross-sectional micro-channel employing simultaneously developing single-phase flows. The numerical code was validated by comparison with previous experimental and numerical results for the same micro-channel dimensions and classical correlations based on conventional sized channels. High heat fluxes up to 130W/cm 2 were applied to investigate micro-channel thermal characteristics. The entire computational domain was discretized using a 120×160×100 grid for the micro-channel with an aspect ratio of (α=4.56) and examined for Reynolds numbers in the laminar range (Re 500-2000) using FLUENT. De-ionized water served as the cooling fluid while the micro-channel substrate used was made of copper. Validation results were found to be in good agreement with previous experimental and numerical data [1] with an average deviation of less than 4.2%. As the applied heat flux increased, an increase in heat transfer coefficient values was observed. Also, the Reynolds number required for transition from single-phase fluid to two-phase was found to increase. A correlation is proposed for the results of average Nusselt numbers for the heat transfer characteristics in micro-channels with simultaneously developing, single-phase flows. © 2011 Elsevier Ltd.

  10. THE CALCULATION OF THE PROFILE-LINEAR AVERAGE VELOCITY IN THE TRANSITION REGION FOR ULTRASONIC HEAT METER BASED ON THE METHOD OF LES*

    Institute of Scientific and Technical Information of China (English)

    LIU Yong-hui; DU Guang-sheng; TAO Li-li; SHEN Fang

    2011-01-01

    The measurement accuracy of an ultrasonic heat meter depends on the relationship of the profile-linear average velocity.There are various methods for the calculation of the laminar and turbulence flow regions, but few methods for the transition region.At present, the traditional method to deal with the transition region is to adopt the relationship for the turbulent flow region. In this article, a simplified model of the pipe is used to study the characteristics of the transition flow with specific Reynolds number. The k-ε model and the Large Eddy Simulation (LES) model are, respectively, used to calculate the flow field of the transition region,and a comparison with the experiment results shows that the LES model is more effective than the k- ε model, it is also shown that there will be a large error if the relationship based on the turbulence flow is used to calculate the profile-linear average velocity relationship of the transition flow. The profile-linear average velocity for the Reynolds number ranging from 5 300 to 10 000 are calculated, and the relationship curve is obtained. The results of this article can be used to improve the measurement accuracy of ultrasonic heat meter and provide a theoretical basis for the research of the whole transition flow.

  11. Information Entropy- and Average-Based High-Resolution Digital Storage Oscilloscope

    Directory of Open Access Journals (Sweden)

    Jun Jiang

    2014-01-01

    Full Text Available Vertical resolution is an essential indicator of digital storage oscilloscope (DSO and the key to improving resolution is to increase digitalizing bits and lower noise. Averaging is a typical method to improve signal to noise ratio (SNR and the effective number of bits (ENOB. The existing averaging algorithm is apt to be restricted by the repetitiveness of signal and be influenced by gross error in quantization, and therefore its effect on restricting noise and improving resolution is limited. An information entropy-based data fusion and average-based decimation filtering algorithm, proceeding from improving average algorithm and in combination with relevant theories of information entropy, are proposed in this paper to improve the resolution of oscilloscope. For single acquiring signal, resolution is improved through eliminating gross error in quantization by utilizing the maximum entropy of sample data with further noise filtering via average-based decimation after data fusion of efficient sample data under the premise of oversampling. No subjective assumptions and constraints are added to the signal under test in the whole process without any impact on the analog bandwidth of oscilloscope under actual sampling rate.

  12. High Efficiency Microchannel Diamond Heat Sinks Project

    Data.gov (United States)

    National Aeronautics and Space Administration — While absolute power levels in microelectronic devices are relatively modest (a few tens to a few hundred watts), heat fluxes can be significant (~50 W/cm2 in...

  13. Average gene length is highly conserved in prokaryotes and eukaryotes and diverges only between the two kingdoms.

    Science.gov (United States)

    Xu, Lin; Chen, Hong; Hu, Xiaohua; Zhang, Rongmei; Zhang, Ze; Luo, Z W

    2006-06-01

    The average length of genes in a eukaryote is larger than in a prokaryote, implying that evolution of complexity is related to change of gene lengths. Here, we show that although the average lengths of genes in prokaryotes and eukaryotes are much different, the average lengths of genes are highly conserved within either of the two kingdoms. This suggests that natural selection has clearly set a strong limitation on gene elongation within the kingdom. Furthermore, the average gene size adds another distinct characteristic for the discrimination between the two kingdoms of organisms.

  14. Measuring Specific Heats at High Temperatures

    Science.gov (United States)

    Vandersande, Jan W.; Zoltan, Andrew; Wood, Charles

    1987-01-01

    Flash apparatus for measuring thermal diffusivities at temperatures from 300 to 1,000 degrees C modified; measures specific heats of samples to accuracy of 4 to 5 percent. Specific heat and thermal diffusivity of sample measured. Xenon flash emits pulse of radiation, absorbed by sputtered graphite coating on sample. Sample temperature measured with thermocouple, and temperature rise due to pulse measured by InSb detector.

  15. Constructs of highly effective heat transport paths by bionic optimization

    Institute of Scientific and Technical Information of China (English)

    CHENG; Xinguang; (程新广); LI; Zhixin; (李志信); GUO; Zengyuan; (过增元)

    2003-01-01

    The optimization approach based on the biological evolution principle is used to construct the heat transport paths for volume-to-point problem. The transport paths are constructed by inserting high conductivity materials in the heat conduction domain where uniform or nonuniform heat sources exist. In the bionic optimization process, the optimal constructs of the high conductivity material are obtained by numerically simulating the evolution and degeneration process according to the uniformity principle of the temperature gradient. Finally, preserving the features of the optimal constructs, the constructs are regularized for the convenience of engineering manufacture. The results show that the construct obtained by bionic optimization is approximate to that obtained by the tree-network constructal theory when the heat conduction is enhanced for the domain with a uniform heat source and high conductivity ratio of the inserting material to the substrate, the high conductivity materials are mainly concentrated on the heat outlet for the case with a uniform heat source and low thermal conductivity ratio, and for the case with nonuniform heat sources, the high conductivity material is concentrated in the heat source regions and construacts several highly effective heat transport paths to connect the regions to the outlet.

  16. The development of early numeracy skills in kindergarten in low-, average- and high-performance groups

    NARCIS (Netherlands)

    Aunio, P.; Heiskari, P.; van Luit, J.E.H.; Vuorio, J.-M.

    2015-01-01

    In this study, we investigated how early numeracy skills develop in kindergarten-age children. The participants were 235 Finnish children (111 girls and 124 boys). At the time of the first measurement, the average age of the children was 6 years. The measurements were conducted three times during 1

  17. Generation and applications of high average power Mid-IR supercontinuum in chalcogenide fibres

    DEFF Research Database (Denmark)

    Petersen, Christian Rosenberg

    2016-01-01

    Mid-infrared supercontinuum with up to 54.8 mW average power, and maximum bandwidth of 1.77-8.66 μm is demonstrated as a result of pumping tapered chalcogenide photonic crystal fibers with a MHz parametric source at 4 μm....

  18. Charge and fluence lifetime measurements of a dc high voltage GaAs photogun at high average current

    Energy Technology Data Exchange (ETDEWEB)

    J. Grames, R. Suleiman, P.A. Adderley, J. Clark, J. Hansknecht, D. Machie, M. Poelker, M.L. Stutzman

    2011-04-01

    GaAs-based dc high voltage photoguns used at accelerators with extensive user programs must exhibit long photocathode operating lifetime. Achieving this goal represents a significant challenge for proposed high average current facilities that must operate at tens of milliamperes or more. This paper describes techniques to maintain good vacuum while delivering beam, and techniques that minimize the ill effects of ion bombardment, the dominant mechanism that reduces photocathode yield of a GaAs-based dc high voltage photogun. Experimental results presented here demonstrate enhanced lifetime at high beam currents by: (a) operating with the drive laser beam positioned away from the electrostatic center of the photocathode, (b) limiting the photocathode active area to eliminate photoemission from regions of the photocathode that do not support efficient beam delivery, (c) using a large drive laser beam to distribute ion damage over a larger area, and (d) by applying a relatively low bias voltage to the anode to repel ions created within the downstream beam line. A combination of these techniques provided the best total charge extracted lifetimes in excess of 1000 C at dc beam currents up to 9.5 mA, using green light illumination of bulk GaAs inside a 100 kV photogun.

  19. Heat transfer in high density electronics packaging

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In order to get an insight into the thermal characteristic and to evaluate the thermal reliability of the "System in Packaging"(SIP), a new solution of electronics packaging, a heat transfer model of SIP was developed to predict the heat dissipation capacity and to investigate the effect of different factors on the temperature distribution in the electronics. The affecting parameters under consideration include the thermophysical properties of the substrates, the coefficient of convection heat transfer, the thickness of the chip, and the density of power dissipation. ALGOR, a kind of finite element analysis software,was used to do the model simulation. Based on the sinulation and analysis of the heat conduction and convection resistance, criteria for the thermal design were established and possible measurement for enhancing power dissipation was provided, The results show that the heat transfer model provides a new and effective way to the thermal design and thermal analysis of SIP and to the mechanical analysis for the further investigation of SIP.

  20. Loop heat pipes - highly efficient heat-transfer devices for systems of sun heat supply

    Energy Technology Data Exchange (ETDEWEB)

    Maydanik, Yu. [Ural Branch of the Russian Academy of Sciences, Ekaterinburg (Russian Federation). Inst. of Thermophysics

    2004-07-01

    Loop heat pipes (LHPs) are hermetic heat-transfer devices operating on a closed evaporation-condensation cycle with the use of capillary pressure for pumping the working fluid [1]. In accordance with this, they possess all the main advantages of conventional heat pipes, but, as distinct from the latter, have a considerably higher heat-transfer capacity, especially when operating in the ''antigravity'' regime, when heat is transferred from above downwards. Besides, LHPs possess a higher functional versatility, are adaptable to different operating conditions and provide great scope for various design embodiments. This is achieved at the expense of both the original design of the device and the properties of the wick - a special capillary structure used for the creation of capillary pressure. The LHP schematic diagram is given in Fig. 1. The device contains an evaporator and a condenser - heat exchanger connected by means of smooth-walled pipe-lines with a relatively small diameter intended for separate motion of vapor and liquid. At present loop heat pipes are most extensively employed in thermoregulation systems of spacecrafts. Miniature LHPs are used for cooling electronics and computers. At the same time there exists a considerable potential of using these devices for the recovery of low-grade (waste) heat from different sources, and also in systems of sun heat supply. In the latter case LHPs may serve as an efficient heat-transfer link between a sun collector and a heat accumulator, which has a low thermal resistance and does not consume any additional energy for pumping the working fluid between them. (orig.)

  1. High heat flux transport by microbubble emission boiling

    Science.gov (United States)

    Suzuki, Koichi

    2007-10-01

    In highly subcooled flow boiling, coalescing bubbles on the heating surface collapse to many microbubbles in the beginning of transition boiling and the heat flux increases higher than the ordinary critical heat flux. This phenomenon is called Microbubble Emission Boiling, MEB. It is generated in subcooled flow boiling and the maximum heat flux reaches about 1 kW/cm2(10 MW/m2) at liquid subcooling of 40 K and liquid velocity of 0.5 m/s for a small heating surface of 10 mm×10 mm which is placed at the bottom surface of horizontal rectangular channel. The high pressure in the channel is observed at collapse of the coalescing bubbles and it is closely related the size of coalescing bubbles. Periodic pressure waves are observed in MEB and the heat flux increases linearly in proportion to the pressure frequency. The frequency is considered the frequency of liquid-solid exchange on the heating surface. For the large sized heating surface of 50 mm length×20 mm width, the maximum heat flux obtained is 500 W/cm2 (5 MW/m2) at liquid subcooling of 40 K and liquid velocity of 0.5 m/s. This is considerably higher heat flux than the conventional cooling limit in power electronics. It is difficult to remove the high heat flux by MEB for a longer heating surface than 50 mm by single channel type. A model of advanced cooling device is introduced for power electronics by subcooled flow boiling with impinging jets. Themaxumum cooling heat flux is 500 W/cm2 (5 MW/m2). Microbubble emission boiling is useful for a high heat flux transport technology in future power electronics used in a fuel-cell power plant and a space facility.

  2. State Averages

    Data.gov (United States)

    U.S. Department of Health & Human Services — A list of a variety of averages for each state or territory as well as the national average, including each quality measure, staffing, fine amount and number of...

  3. A comment on the average foil-hit number for a high-intensity proton ring

    CERN Document Server

    Yamane, I

    2002-01-01

    The minimum value of the average foil-hit number is derived for H sup - charge-exchange injection using a stripping foil, in which the H sup - beam is injected at a corner of the stripper foil and the cross-sectional area of the ring beam is increased as a function of time, kt sup 1 sup / sup n , where k and n are constants.

  4. Specific heat of pristine and brominated graphite fibers, composites and HOPG. [Highly Oriented Pyrolytic Graphite

    Science.gov (United States)

    Hung, Ching-Chen; Maciag, Carolyn

    1987-01-01

    Differential scanning calorimetry was used to obtain specific heat values of pristine and brominated P-100 graphite fibers and brominated P-100/epoxy composite as well as pristine and brominated highly oriented pyrolytic graphite (HOPG) for comparison. Based on the experimental results obtained, specific heat values are calculated for several different temperatures, with a standard deviation estimated at 1.4 percent of the average values. The data presented here are useful in designing heat transfer devices (such as airplane de-icing heaters) from bromine fibers.

  5. Heat transparent high intensity high efficiency solar cell

    Science.gov (United States)

    Evans, J. C., Jr. (Inventor)

    1982-01-01

    An improved solar cell design is described. A surface of each solar cell has a plurality of grooves. Each groove has a vertical face and a slanted face that is covered by a reflecting metal. Light rays are reflected from the slanted face through the vertical face where they traverse a photovoltaic junction. As the light rays travel to the slanted face of an adjacent groove, they again traverse the junction. The underside of the reflecting coating directs the light rays toward the opposite surface of solar cell as they traverse the junction again. When the light rays travel through the solar cell and reach the saw toothed grooves on the under side, the process of reflection and repeatedly traversing the junction again takes place. The light rays ultimately emerge from the solar cell. These solar cells are particularly useful at very high levels of insolation because the infrared or heat radiation passes through the cells without being appreciably absorbed to heat the cell.

  6. Numerical prediction of nucleate pool boiling heat transfer coefficient under high heat fluxes

    OpenAIRE

    Pezo Milada L.; Stevanović Vladimir D.

    2016-01-01

    This paper presents CFD (Computational Fluid Dynamics) approach to prediction of the heat transfer coefficient for nucleate pool boiling under high heat fluxes. Three-dimensional numerical simulations of the atmospheric saturated pool boiling are performed. Mathematical modelling of pool boiling requires a treatment of vapor-liquid two-phase mixture on the macro level, as well as on the micro level, such as bubble growth and departure from the heating surfa...

  7. In-volume heating using high-power laser diodes

    NARCIS (Netherlands)

    Denisenkov, V.S.; Kiyko, V.V.; Vdovin, G.V.

    2015-01-01

    High-power lasers are useful instruments suitable for applications in various fields; the most common industrial applications include cutting and welding. We propose a new application of high-power laser diodes as in-bulk heating source for food industry. Current heating processes use surface

  8. In-volume heating using high-power laser diodes

    NARCIS (Netherlands)

    Denisenkov, V.S.; Kiyko, V.V.; Vdovin, G.V.

    2015-01-01

    High-power lasers are useful instruments suitable for applications in various fields; the most common industrial applications include cutting and welding. We propose a new application of high-power laser diodes as in-bulk heating source for food industry. Current heating processes use surface heatin

  9. Low Temperature Heating and High Temperature Cooling in Buildings

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk

    , a single-family house designed for plus-energy targets and equipped with a radiant water-based floor heating and cooling system was studied by means of full-scale measurements, dynamic building simulations and thermodynamic evaluation tools. Thermal indoor environment and energy performance of the house...... performance of heating and cooling systems for achieving the same thermal indoor environment. The results show that it is crucial to minimize the heating and cooling demands in the design phase since these demands determine the terminal units and heat sources and sinks that could be used. Low temperature...... heating and high temperature cooling systems (a radiant water-based floor heating and cooling system in this study) proved to be superior to compared systems, evaluated with different system analysis tools; energy, exergy, and entransy. Radiant systems should be coupled to appropriate heating and cooling...

  10. Multi-session complex averaging for high resolution high SNR 3T MR visualization of ex vivo hippocampus and insula

    Science.gov (United States)

    Stamm, Aymeric; Singh, Jolene M.; Scherrer, Benoit; Afacan, Onur; Warfield, Simon K.

    2015-03-01

    The hippocampus and the insula are responsible for episodic memory formation and retrieval. Hence, visualization of the cytoarchitecture of such structures is of primary importance to understand the underpinnings of conscious experience. Magnetic Resonance Imaging (MRI) offers an opportunity to non-invasively image these crucial structures. However, current clinical MR imaging operates at the millimeter scale while these anatomical landmarks are organized into sub-millimeter structures. For instance, the hippocampus contains several layers, including the CA3-dentate network responsible for encoding events and experiences. To investigate whether memory loss is a result of injury or degradation of CA3/dentate, spatial resolution must exceed one hundred micron, isotropic, voxel size. Going from one millimeter voxels to one hundred micron voxels results in a 1000× signal loss, making the measured signal close to or even way below the precision of the receiving coils. Consequently, the signal magnitude that forms the structural images will be biased and noisy, which results in inaccurate contrast and less than optimal signal-to-noise ratio (SNR). In this paper, we propose a strategy to perform high spatial resolution MR imaging of the hippocampus and insula with 3T scanners that enables accurate contrast (no systematic bias) and arbitrarily high SNR. This requires the collection of additional repeated measurements of the same image and a proper averaging of the k-space data in the complex domain. This comes at the cost of additional scan time, but long single-session scan times are not practical for obvious reasons. Hence, we also develop an approach to combine k-space data from multiple sessions, which enables the total scan time to be split into arbitrarily short sessions, where the patient is allowed to move and rest in-between. For validation, we hereby illustrate our multi-session complex averaging strategy by providing high spatial resolution 3T MR visualization

  11. Active latent heat storage with a screw heat exchanger - experimental results for heat transfer and concept for high pressure steam

    Science.gov (United States)

    Zipf, Verena; Willert, Daniel; Neuhäuser, Anton

    2016-05-01

    An innovative active latent heat storage concept was invented and developed at Fraunhofer ISE. It uses a screw heat exchanger (SHE) for the phase change during the transport of a phase change material (PCM) from a cold to a hot tank or vice versa. This separates heat transfer and storage tank in comparison to existing concepts. A test rig has been built in order to investigate the heat transfer coefficients of the SHE during melting and crystallization of the PCM. The knowledge of these characteristics is crucial in order to assess the performance of the latent heat storage in a thermal system. The test rig contains a double shafted SHE, which is heated or cooled with thermal oil. The overall heat transfer coefficient U and the convective heat transfer coefficient on the PCM side hPCM both for charging and discharging have been calculated based on the measured data. For charging, the overall heat transfer coefficient in the tested SHE was Uch = 308 W/m2K and for discharging Udis = 210 W/m2K. Based on the values for hPCM the overall heat transfer coefficients for a larger SHE with steam as heat transfer fluid and an optimized geometry were calculated with Uch = 320 W/m2K for charging and Udis = 243 W/m2K for discharging. For pressures as high as p = 100 bar, an SHE concept has been developed, which uses an organic fluid inside the flight of the SHE as working media. With this concept, the SHE can also be deployed for very high pressure, e.g. as storage in solar thermal power plants.

  12. Development of a Two-Dimensional Zonally Averaged Statistical-Dynamical Model. Part III: The Parameterization of the Eddy Fluxes of Heat and Moisture.

    Science.gov (United States)

    Stone, Peter H.; Yao, Mao-Sung

    1990-07-01

    A number of perpetual January simulations are carried out with a two-dimensional (2-D) zonally averaged model employing various parameterizations of the eddy fluxes of heat (potential temperature) and moisture. The parameterizations are evaluated by comparing these results with the eddy fluxes calculated in a parallel simulation using a three-dimensional (3-D) general circulation model with zonally symmetric forcing. The 3-D model's performance in turn is evaluated by comparing its results using realistic (nonsymmetric) boundary conditions with observations.Branscome's parameterization of the meridional eddy flux of heat and Leovy's parameterization of the meridional eddy flux of moisture simulate the seasonal and latitudinal variations of these fluxes reasonably well, while somewhat underestimating their magnitudes. In particular, Branscome's parameterization underestimates the vertically integrated flux of heat by about 30%, mainly because it misses out the secondary peak in this flux near the tropopause; and Leovy's parameterization of the meridional eddy flux of moisture underestimates the magnitude of this flux by about 20%. The analogous parameterizations of the vertical eddy fluxes of heat and moisture are found to perform much more poorly, i.e., they give fluxes only one quarter to one half as strong as those calculated in the 3-D model. New parameterizations of the vertical eddy fluxes are developed that take into account the enhancement of the eddy mixing slope in a growing baroclinic wave due to condensation, and also the effect of eddy fluctuations in relative humidity. The new parameterizations, when tested in the 2-D model, simulate the seasonal, latitudinal, and vertical variations of the vertical eddy fluxes quite well, when compared with the 3-D model, and only underestimate the magnitude of the fluxes by 10% to 20%.

  13. Multi-Repeated Projection Lithography for High-Precision Linear Scale Based on Average Homogenization Effect

    Directory of Open Access Journals (Sweden)

    Dongxu Ren

    2016-04-01

    Full Text Available A multi-repeated photolithography method for manufacturing an incremental linear scale using projection lithography is presented. The method is based on the average homogenization effect that periodically superposes the light intensity of different locations of pitches in the mask to make a consistent energy distribution at a specific wavelength, from which the accuracy of a linear scale can be improved precisely using the average pitch with different step distances. The method’s theoretical error is within 0.01 µm for a periodic mask with a 2-µm sine-wave error. The intensity error models in the focal plane include the rectangular grating error on the mask, static positioning error, and lithography lens focal plane alignment error, which affect pitch uniformity less than in the common linear scale projection lithography splicing process. It was analyzed and confirmed that increasing the repeat exposure number of a single stripe could improve accuracy, as could adjusting the exposure spacing to achieve a set proportion of black and white stripes. According to the experimental results, the effectiveness of the multi-repeated photolithography method is confirmed to easily realize a pitch accuracy of 43 nm in any 10 locations of 1 m, and the whole length accuracy of the linear scale is less than 1 µm/m.

  14. Multi-Repeated Projection Lithography for High-Precision Linear Scale Based on Average Homogenization Effect.

    Science.gov (United States)

    Ren, Dongxu; Zhao, Huiying; Zhang, Chupeng; Yuan, Daocheng; Xi, Jianpu; Zhu, Xueliang; Ban, Xinxing; Dong, Longchao; Gu, Yawen; Jiang, Chunye

    2016-04-14

    A multi-repeated photolithography method for manufacturing an incremental linear scale using projection lithography is presented. The method is based on the average homogenization effect that periodically superposes the light intensity of different locations of pitches in the mask to make a consistent energy distribution at a specific wavelength, from which the accuracy of a linear scale can be improved precisely using the average pitch with different step distances. The method's theoretical error is within 0.01 µm for a periodic mask with a 2-µm sine-wave error. The intensity error models in the focal plane include the rectangular grating error on the mask, static positioning error, and lithography lens focal plane alignment error, which affect pitch uniformity less than in the common linear scale projection lithography splicing process. It was analyzed and confirmed that increasing the repeat exposure number of a single stripe could improve accuracy, as could adjusting the exposure spacing to achieve a set proportion of black and white stripes. According to the experimental results, the effectiveness of the multi-repeated photolithography method is confirmed to easily realize a pitch accuracy of 43 nm in any 10 locations of 1 m, and the whole length accuracy of the linear scale is less than 1 µm/m.

  15. Highly efficient sparse-matrix inversion techniques and average procedures applied to collisional-radiative codes

    CERN Document Server

    Poirier, M

    2009-01-01

    The behavior of non-local thermal-equilibrium (NLTE) plasmas plays a central role in many fields of modern-day physics, such as laser-produced plasmas, astrophysics, inertial or magnetic confinement fusion devices, or X-ray sources. The proper description of these media in stationary cases requires to solve linear systems of thousands or more rate equations. A possible simplification for this arduous numerical task may lie in some type of statistical average, such as configuration or superconfiguration average. However to assess the validity of this procedure and to handle cases where isolated lines play an important role, it may be important to deal with detailed levels systems. This involves matrices with sometimes billions of elements, which are rather sparse but still involve thousands of diagonals. We propose here a numerical algorithm based on the LU decomposition for such linear systems. This method turns out to be orders of magnitude faster than the traditional Gauss elimination. And at variance with ...

  16. Heat Pipe Embedded AlSiC Plates for High Conductivity - Low CTE Heat Spreaders

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Matthew (DOE/NNSA Kansas City Plant (United States)); Weyant, J.; Garner, S. (Advanced Cooling Technologies, Inc. (Lancaster, PA (United States)); Occhionero, M. (CPS Technologies Corporation, Norton, MA (United States))

    2010-01-07

    Heat pipe embedded aluminum silicon carbide (AlSiC) plates are innovative heat spreaders that provide high thermal conductivity and low coefficient of thermal expansion (CTE). Since heat pipes are two phase devices, they demonstrate effective thermal conductivities ranging between 50,000 and 200,000 W/m-K, depending on the heat pipe length. Installing heat pipes into an AlSiC plate dramatically increases the plate’s effective thermal conductivity. AlSiC plates alone have a thermal conductivity of roughly 200 W/m-K and a CTE ranging from 7-12 ppm/ deg C, similar to that of silicon. An equivalent sized heat pipe embedded AlSiC plate has effective thermal conductivity ranging from 400 to 500 W/m-K and retains the CTE of AlSiC.

  17. High Heat Load Properties of Ultra Fine Grain Tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Z.; Du, J.; Ge, C. [Lab. of Special Ceramic and P/M, University of Science and Technology, 100083 Beijing (China); Linke, J.; Pintsuk, G. [FZJ-Forschungszentrum Juelich GmbH, Association Euratom-FZJ, Institut fur Plasmaphysik, Postfach 1913, D-52425 Juelich (Germany); Song, S.X. [Research Center on Fusion Materials (RCFM), University of Science and Technology Beijing (USTB), 100083 Beijing (China)

    2007-07-01

    Full text of publication follows: Tungsten is increasingly considered as a promising candidate armour materials facing the plasma in tokamaks for medium to high heat flux components (EAST, ASDEX, ITER). Fabrication tungsten with ultra fine grain size is considered as an effective way to ameliorate some disadvantages of tungsten, such as its brittleness at room temperature. But the research data on the performance of ultra fine grain tungsten is still very limit. In this work, high heat load properties of pure ultra-fine grain tungsten have been studied. The ultra fine grain tungsten samples with average grain size of 0.2 {mu}m, 1 {mu}m and 3 {mu}m were fabricated by resistance sintering under ultra high pressure. The annealing experiments for the investigation of the material resistance against grain growth have been done by annealing samples in a vacuum furnace at different temperature holding for 2 hours respectively. It is found that recrystallization and grain growth occur at heating temperature of 1250 deg. c. The finer the initial grain sizes of tungsten, the smaller its grain growth grain. The effects of transient high thermal loads (off normal events like disruptions) on tungsten surface morphology have been performed in electron beam test facility JUDITH. The thermal loads tests have been carried out with 4 ms pulses at different power density of 0.22, 0.33, 0.44, 0.55 and 0.88 GW/m{sup 2} respectively. Horizontal cracks formed for all tungsten samples at 0.44 GW/m{sup 2}. Particle erosions occurred for tungsten with 3 {mu}m size at 0.33 GW/m{sup 2} and for tungsten with 0.2 and 1 {mu}m size at 0.55 GW/m{sup 2}. The weight loss of tungsten with 0.2, 1 and 3 {mu}m size are 2,0.1,0.6 mg respectively at 0.88 GW/m{sup 2}. The effects of a large number of very short transient repetitive thermal loads (ELM-like) on tungsten surface morphology also have been performed by using a fundamental wave of a YAG laser. It is found that tungsten with 0.2 {mu}m size has

  18. High-average-power high-beam-quality vis-UV sources based on kinetically enhanced copper vapor lasers

    Science.gov (United States)

    Brown, Daniel J. W.; Withford, Michael J.; Carman, Robert J.; Mildren, Richard P.; Piper, James A.

    2000-04-01

    Investigations of the factors that limit average power scaling of elemental copper vapor lasers (CVLs) have demonstrated that decay of the electron density in the interpulse period is critical in restricting pulse repetition rate and laser aperture scaling. We have recently developed the 'kinetic enhancement' (or KE) technique to overcome these limitations, whereby optimal plasma conditions are engineered using low concentrations of HCl/H2 additive gases in the Ne buffer. Dissociative electron attachment of HCl and subsequent mutual neutralization of Cl- and Cu+ promote rapid plasma relaxation and fast recovery of Cu densities, permitting operation at elevated Cu densities and pulse rates for given apertures. Using this approach, we have demonstrated increases in output power and efficiency of a factor of 2 or higher over conventional CVLs of the same size. For a 38 mm- bore KE-CVL, output powers up to 150 W have been achieved at 22 kHz, corresponding to record specific powers (80 mW/cm3) for such a 'small/medium-scale' device. In addition, kinetic enhancement significantly extends the gain duration and restores gain on-axis, even for high pulse rates, thereby promoting substantial increases (5 - 10x) in high- beam-quality power levels when operating with unstable resonators. This has enabled us to achieve much higher powers in second-harmonic generation from the visible copper laser output to the ultraviolet (e.g. 5 W at 255 nm from a small- scale KE-CVL). Our approach to developing KE-CVLs including computer modeling and experimental studies will be reviewed, and most recent results in pulse rate scaling and scaling of high-beam-quality power using oscillator-amplifier configurations, will be presented.

  19. Baseline high heat flux and plasma facing materials for fusion

    Science.gov (United States)

    Ueda, Y.; Schmid, K.; Balden, M.; Coenen, J. W.; Loewenhoff, Th.; Ito, A.; Hasegawa, A.; Hardie, C.; Porton, M.; Gilbert, M.

    2017-09-01

    In fusion reactors, surfaces of plasma facing components (PFCs) are exposed to high heat and particle flux. Tungsten and Copper alloys are primary candidates for plasma facing materials (PFMs) and coolant tube materials, respectively, mainly due to high thermal conductivity and, in the case of tungsten, its high melting point. In this paper, recent understandings and future issues on responses of tungsten and Cu alloys to fusion environments (high particle flux (including T and He), high heat flux, and high neutron doses) are reviewed. This review paper includes; Tritium retention in tungsten (K. Schmid and M. Balden), Impact of stationary and transient heat loads on tungsten (J.W. Coenen and Th. Loewenhoff), Helium effects on surface morphology of tungsten (Y. Ueda and A. Ito), Neutron radiation effects in tungsten (A. Hasegawa), and Copper and copper alloys development for high heat flux components (C. Hardie, M. Porton, and M. Gilbert).

  20. 家用太阳能热水系统平均热损因数数值的探讨%Probe into Numerical Value of Domestic Solar Water Heating Systems Average Heat Loss Factor

    Institute of Scientific and Technical Information of China (English)

    肖红升

    2012-01-01

    GB/T 19141-2011家用太阳能热水系统技术条件国家标准已于2012年8月1日起实施.该标准规定平均热损因数数值保留至个位数.这一要求对开展实验室间比对、实施GB 26969-2011等带来一些困惑.本文通过对就平均热损因数开展实验室间比对和能效系数计算、能效等级判定等展开探讨,找出了不合理的原因,得出了将平均热损因数数值保留一位小数可以提高该标准的严谨性,有效化解一些矛盾的研究结论.%The national standard named as GB/T19141-2011 specification of domestic solar water heating systems has already been put into effect since August 1, 2012, which stipulates that numerical value of average heat loss factor is accurate to the digit. This demand brings some confusion to doing comparison between laboratories as well as carrying out GB26969-2011. This paper conducts a series of discussions about carrying out comparison between laboratories on average heat loss factor, calculating the coefficient of thermal performance and judging the grade of thermal performance, finding out the reason of its irrationality. The conclusion is reached that numerical value of average heat loss factor being accurate to the first decimal place can enhance the conscientiousness of the this standard and thus solve some contradictions.

  1. High-temperature waste-heat-stream selection and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Wikoff, P.M.; Wiggins, D.J.; Tallman, R.L.; Forkel, C.E.

    1983-08-01

    Four types of industrial high-temperature, corrosive waste heat streams are selected that could yield significant energy savings if improved heat recovery systems were available. These waste heat streams are the flue gases from steel soaking pits, steel reheat furnaces, aluminum remelt furnaces, and glass melting furnaces. Available information on the temperature, pressure, flow, and composition of these flue gases is given. Also reviewed are analyses of corrosion products and fouling deposits resulting from the interaction of these flue gases with materials in flues and heat recovery systems.

  2. Heat pumps; Synergy of high efficiency and low carbon electricity

    Energy Technology Data Exchange (ETDEWEB)

    Koike, Akio

    2010-09-15

    Heat pump is attracting wide attention for its high efficiency to utilize inexhaustible and renewable ambient heat in the environment. With its rapid innovation and efficiency improvement, this technology has a huge potential to reduce CO2 emissions by replacing currently widespread fossil fuel combustion systems to meet various heat demands from the residential, commercial and industrial sectors. Barriers to deployment such as low public awareness and a relatively long pay-back period do exist, so it is strongly recommended that each country implement policies to promote heat pumps as a renewable energy option and an effective method to combat global warming.

  3. NEO-LISP: Deflecting near-Earth objects using high average power, repetitively pulsed lasers

    Science.gov (United States)

    Phipps, C. R.; Michaelis, M. M.

    Several kinds of Near-Earth objects exist for which one would like to cause modest orbit perturbations, but which are inaccessible to normal means of interception because of their number, distance or the lack of early warning. For these objects, LISP (Laser Impulse Space Propulsion) is an appropriate technique for rapidly applying the required mechanical impulse from a ground-based station. In order of increasing laser energy required, examples are: (1) repositioning specially prepared geosynchronous satellites for an enhanced lifetime; (2) causing selected items of space junk to re-enter and burn up in the atmosphere on a computed trajectory; and (3) safely deflecting Earth-directed comet nuclei and earth-crossing asteroids (ECA's) a few tens of meters in size (the most hazardous size). They will discuss each of these problems in turn and show that each application is best matched by its own matrix of LISP laser pulse width, pulse repetition rate, wavelength and average power. The latter ranges from 100W to 3GW for the cases considered. They will also discuss means of achieving the active beam phase error correction during passage through the atmosphere and very large exit pupil in the optical system which are required in each of these cases.

  4. In-volume heating using high-power laser diodes

    Science.gov (United States)

    Denisenkov, Valentin S.; Kiyko, Vadim V.; Vdovin, Gleb V.

    2015-03-01

    High-power lasers are useful instruments suitable for applications in various fields; the most common industrial applications include cutting and welding. We propose a new application of high-power laser diodes as in-bulk heating source for food industry. Current heating processes use surface heating with different approaches to make the heat distribution more uniform and the process more efficient. High-power lasers can in theory provide in-bulk heating which can sufficiently increase the uniformity of heat distribution thus making the process more efficient. We chose two media (vegetable fat and glucose) for feasibility experiments. First, we checked if the media have necessary absorption coefficients on the wavelengths of commercially available laser diodes (940-980 nm). This was done using spectrophotometer at 700-1100 nm which provided the dependences of transmission from the wavelength. The results indicate that vegetable fat has noticeable transmission dip around 925 nm and glucose has sufficient dip at 990 nm. Then, after the feasibility check, we did numerical simulation of the heat distribution in bulk using finite elements method. Based on the results, optimal laser wavelength and illuminator configuration were selected. Finally, we carried out several pilot experiments with high-power diodes heating the chosen media.

  5. Microbial Carbon Substrate Utilization Differences among High- and Average-Yield Soybean Areas

    National Research Council Canada - National Science Library

    Taylor C. Adams; Kristofor R. Brye; Mary C. Savin; Jung Ae Lee; Edward E. Gbur

    2017-01-01

    Since soybean (Glycine max L. (Merr.)) yields greater than 6719 kg ha−1 have only recently and infrequently been achieved, little is known about the soil microbiological environment related to high-yield soybean production...

  6. Development of a two-dimensional zonally averaged statistical-dynamical model. III - The parameterization of the eddy fluxes of heat and moisture

    Science.gov (United States)

    Stone, Peter H.; Yao, Mao-Sung

    1990-01-01

    A number of perpetual January simulations are carried out with a two-dimensional zonally averaged model employing various parameterizations of the eddy fluxes of heat (potential temperature) and moisture. The parameterizations are evaluated by comparing these results with the eddy fluxes calculated in a parallel simulation using a three-dimensional general circulation model with zonally symmetric forcing. The three-dimensional model's performance in turn is evaluated by comparing its results using realistic (nonsymmetric) boundary conditions with observations. Branscome's parameterization of the meridional eddy flux of heat and Leovy's parameterization of the meridional eddy flux of moisture simulate the seasonal and latitudinal variations of these fluxes reasonably well, while somewhat underestimating their magnitudes. New parameterizations of the vertical eddy fluxes are developed that take into account the enhancement of the eddy mixing slope in a growing baroclinic wave due to condensation, and also the effect of eddy fluctuations in relative humidity. The new parameterizations, when tested in the two-dimensional model, simulate the seasonal, latitudinal, and vertical variations of the vertical eddy fluxes quite well, when compared with the three-dimensional model, and only underestimate the magnitude of the fluxes by 10 to 20 percent.

  7. Thermal performance of a flat polymer heat pipe heat spreader under high acceleration

    Science.gov (United States)

    Oshman, Christopher; Li, Qian; Liew, Li-Anne; Yang, Ronggui; Lee, Y. C.; Bright, Victor M.; Sharar, Darin J.; Jankowski, Nicholas R.; Morgan, Brian C.

    2012-04-01

    This paper presents the fabrication and application of a micro-scale hybrid wicking structure in a flat polymer-based heat pipe heat spreader, which improves the heat transfer performance under high adverse acceleration. The hybrid wicking structure which enhances evaporation and condensation heat transfer under adverse acceleration consists of 100 µm high, 200 µm wide square electroplated copper micro-pillars with 31 µm wide grooves for liquid flow and a woven copper mesh with 51 µm diameter wires and 76 µm spacing. The interior vapor chamber of the heat pipe heat spreader was 30×30×1.0 mm3. The casing of the heat spreader is a 100 µm thick liquid crystal polymer which contains a two-dimensional array of copper-filled vias to reduce the overall thermal resistance. The device performance was assessed under 0-10 g acceleration with 20, 30 and 40 W power input on an evaporator area of 8×8 mm2. The effective thermal conductivity of the device was determined to range from 1653 W (m K)-1 at 0 g to 541 W (m K)-1 at 10 g using finite element analysis in conjunction with a copper reference sample. In all cases, the effective thermal conductivity remained higher than that of the copper reference sample. This work illustrates the possibility of fabricating flexible, polymer-based heat pipe heat spreaders compatible with standardized printed circuit board technologies that are capable of efficiently extracting heat at relatively high dynamic acceleration levels.

  8. Thermal evaluation of uranium silicide miniplates irradiated at high heat flux

    Energy Technology Data Exchange (ETDEWEB)

    Post Guillen, Donna, E-mail: Donna.Guillen@inl.gov [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415-3710 (United States)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Best estimate of thermal conditions during irradiation experiment. Black-Right-Pointing-Pointer Thermal evaluation of 25% enriched, high-density U{sub 3}Si{sub 2}/Al dispersion fuel miniplates. Black-Right-Pointing-Pointer Predictions of heat flux and temperature for as-run, high heat flux conditions. Black-Right-Pointing-Pointer Finite-element analysis uses measured values of hydroxide layer thickness. - Abstract: The Gas Test Loop (GTL)-1 irradiation experiment was conducted in the Advanced Test Reactor (ATR) to assess corrosion performance of proposed booster fuel at heat flux levels {approx}30% above the design operating condition. Sixteen miniplates fabricated from 25% enriched, high-density (4.8 g U/cm{sup 3}) U{sub 3}Si{sub 2}/Al dispersion fuel with 6061 aluminum cladding were subjected to peak beginning of cycle (BOC) heat fluxes ranging from 411 to 593 W/cm{sup 2}. No adverse impacts to the miniplates were observed at these high heat flux levels. A detailed finite element model was constructed to calculate temperatures and heat flux for an as-run cycle average effective ATR south lobe power of 25.4 MW(t). Miniplate heat flux levels and fuel, cladding, hydroxide, and coolant-hydroxide interface temperatures were calculated using the average hydroxide thickness on each miniplate measured during post-irradiation examination. The purpose of this study was to obtain a best estimate of the as-run experiment temperatures to aid in establishing acceptable heat flux levels and designing fuel qualification experiments for this fuel type.

  9. Experimental Study on the Impact of External Geometrical Shape on Free and Forced Convection Time Dependent Average Heat Transfer Coefficient during Cooling Process

    Directory of Open Access Journals (Sweden)

    Sundus Hussein Abd

    2012-01-01

    Full Text Available In this research, an experimental study was conducted to high light the impact of the exterior shape of a cylindrical body on the forced and free convection heat transfer coefficients when the body is hold in the entrance of an air duct. The impact of changing the body location within the air duct and the air speed are also demonstrated. The cylinders were manufactured with circular, triangular and square sections of copper for its high thermal conductivity with appropriate dimensions, while maintaining the surface area of all shapes to be the same. Each cylinder was heated to a certain temperature and put inside the duct at certain locations. The temperature of the cylinder was then monitored. The heat transfer coefficient were then calculated for forced convection for several Reynolds number (4555-18222.The study covered free convection impact for values of Rayleigh number ranging between (1069-3321. Imperical relationships were obtained for all cases of forced and free convection and compared with equations of circular cylindrical shapes found in literature. These imperical equations were found to be in good comparison with that of other sources.

  10. Visualization Study on High Heat Flux Boiling and Critical Heat Flux

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Satbyoul; Kim, Hyungdae [Kyung Hee University, Yongin (Korea, Republic of)

    2015-10-15

    In this study, an integrated visible and infrared-based experimental method is introduced to simultaneously measure the details of high-resolution liquid-vapor phase and heat transfer distributions on a heated wall. The dynamics and heat transfer at high heat flux boiling and critical heat flux were observed. The experiment was conducted in pool of saturated water under atmospheric pressure. There have been many studies to examine the physical mechanisms of nucleation boiling and critical heat flux over several decades. Several visible and infrared-based optical techniques for time-resolved high resolution measurements for liquid-vapor phase and heater surface temperature during boiling have been introduced to understand the characteristics and mechanisms of them. Liquid-vapor phase, temperature, and heat flux distributions on the heated surface were measured during pool boiling of water using the integrated total reflection and infrared thermometry technique. Qualitative examination of the data for high heat flux boiling and CHF was performed. The main contributions of this work are summarized below. The existence and behavior of dry patches lead the way toward CHF condition. Therefore, the mechanistic modeling of the CHF phenomenon necessarily needs to include the physical parameters related to dynamics of the large dry patch such as life time and size. In addition to the dynamic behavior of the dry patch, the thermal behavior of the hot patch is also important. Even though the dry area was rewetted, the stored thermal energy in the hot patch can be remained if the rewetting time is short and the subsequent dry patch is regenerated quickly.

  11. Is it better to be average? High and low performance as predictors of employee victimization.

    Science.gov (United States)

    Jensen, Jaclyn M; Patel, Pankaj C; Raver, Jana L

    2014-03-01

    Given increased interest in whether targets' behaviors at work are related to their victimization, we investigated employees' job performance level as a precipitating factor for being victimized by peers in one's work group. Drawing on rational choice theory and the victim precipitation model, we argue that perpetrators take into consideration the risks of aggressing against particular targets, such that high performers tend to experience covert forms of victimization from peers, whereas low performers tend to experience overt forms of victimization. We further contend that the motivation to punish performance deviants will be higher when performance differentials are salient, such that the effects of job performance on covert and overt victimization will be exacerbated by group performance polarization, yet mitigated when the target has high equity sensitivity (benevolence). Finally, we investigate whether victimization is associated with future performance impairments. Results from data collected at 3 time points from 576 individuals in 62 work groups largely support the proposed model. The findings suggest that job performance is a precipitating factor to covert victimization for high performers and overt victimization for low performers in the workplace with implications for subsequent performance.

  12. Space qualification of high capacity grooved heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, M.; Mullender, B.; Druart, J. [SABCA, Societe Anomyme Belgel de Construction Aeronautique (Belgium); Supper, W.; Beddows, A. [ESTEC-The (Netherlands)

    1996-12-31

    Based on the thermal requirements of the future telecommunication satellites, the development of a High Capacity Grooved Heat Pipe (HPG), was contracted by ESA to SABCA leading to an aluminium extruded heat pipe (outer diameter of 25 mm) based on a multi re-entrant grooves design. After an intensive acceptance test campaign whose results showed a good confidence in the design and the fulfillment of the required specifications of heat transport and on tilt capability (experimental maximum heat transport capability of 1500 Watt metres for a vapour temperature of 20 deg C), similar heat pipes have been developed with various outer diameters (11 mm, 15 mm and 20 mm) and with various shapes (circular outer shapes, integrated saddles). Several of these heat pipes were tested during two parabolic flight campaigns, by varying the heat loads during the micro-gravity periods. This HGP heat pipe family is now being submitted to a space qualification program according to ESA standards (ESA PSS-49), both in straight and bent configuration. Within this qualification, the heat pipes are submitted to an extended test campaign including environmental (random/sinus vibration, constant acceleration) and thermal tests (thermal performance, thermal cycle, thermal soak, ageing). (authors) 9 refs.

  13. A laser-induced heat flux technique for convective heat transfer measurements in high speed flows

    Science.gov (United States)

    Porro, A. R.; Keith, T. G., Jr.; Hingst, W. R.

    1991-01-01

    A technique is developed to measure the local convective heat transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local heat flux at the model test surface, and an infrared camera system determines the local temperature distribution due to the heating. From this temperature distribution and an analysis of the heating process, a local convective heat transfer coefficient is determined. The technique was used to measure the local surface convective heat transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimentally determined convective heat transfer coefficients were generally higher than the theoretical predictions for flat plate laminar boundary layers. However, the results indicate that this nonintrusive optical measurement technique has the potential to measure surface convective heat transfer coefficients in high-speed flowfields.

  14. AVERAGE GEOMETRICAL FEATURES OF THE ELECTRON WAVE PACKAGES DISTRIBUTION IN METALLIC CONDUCTORS WITH PULSED AXIAL CURRENT OF HIGH DENSITY

    Directory of Open Access Journals (Sweden)

    M. I. Baranov

    2016-11-01

    Full Text Available Purpose. Calculation and experimental determination of average geometrical features of distributing of macroscopic electron wave packages (EWP in round cylindrical metallic conductors with the pulsed axial current of high density. Methodology. Theoretical bases of the electrical engineering, bases of atomic and quantum physics, electrophysics bases of technique of high voltage and high pulsed currents. Results. The results of the conducted calculation and experimental researches are resulted on close determination of average geometrical features of distribution of longitudinal and radial EWP of macroscopic sizes in the indicated conductors. These descriptions are included by the average widths of «hot» and «cold» longitudinal and radial areas of conductor, and also average steps of division into the periods of similar areas. Results of the executed calculations and high temperature experiments for average geometrical features of longitudinal EWP in the zincked steel wire of diameter of 1.6 mm and length of 320 mm with the aperiodic impulse of current of temporal form 9 ms/160 ms and by amplitude 745 A coincide within the limits of 19 %. Originality. First with the use of methods of atomic and quantum physics the features of the stochastic distributing and mean values of basic geometrical sizes are analysed macroscopic longitudinal and radial EWP in round cylindrical metallic conductors with the pulsed axial current of high density. Practical value. Drawing on the got results in practice will allow more reliably to forecast geometrical sizes and places of localization of arising up in the probed metallic conductors with pulsed axial current of high density longitudinal and radial EWP.

  15. High Effectiveness Heat Exchanger for Cryogenic Refrigerators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose an innovative high performance cryogenic heat exchanger manufactured of titanium by photo-etching and diffusion bonding. This is a parallel plate design...

  16. Solid State Raman Materials Characterization for High Average Power 1.3 micrometer Laser Frequency Shift

    Science.gov (United States)

    1999-01-01

    reflectivity at 1067 rim wavelength. Solid state phototrop filter based on gallium -scandium- gadolinium garnet doped with chromium was used as a passive Q-switch... gadolinium tungstate, KGd(W0 4)2 exhibited efficient Raman properties . In spite of the fact that its Raman gain coefficient at 1064 nm (6 cm/GW) is twice less...studied by high- temperature Raman scattering (HTRS) technique. According to [1], the lattice cell of KGd(W04) 2 low - temperature modification is a base

  17. The Effect of Computer Based Instructional Technique for the Learning of Elementary Level Mathematics among High, Average and Low Achievers

    Science.gov (United States)

    Afzal, Muhammad Tanveer; Gondal, Bashir; Fatima, Nuzhat

    2014-01-01

    The major objective of the study was to elicit the effect of three instructional methods for teaching of mathematics on low, average and high achiever elementary school students. Three methods: traditional instructional method, computer assisted instruction (CAI) and teacher facilitated mathematics learning software were employed for the teaching…

  18. Are Confidence Ratings Test- or Trait-Driven? Individual Differences among High, Average, and Low Comprehenders in Fourth Grade

    Science.gov (United States)

    Kasperski, Ronen; Katzir, Tami

    2013-01-01

    The aim of this study was to examine whether low, average, and high comprehenders (LC, AC, and HC, respectively) differed in their reading self-confidence and bias ratings, and whether confidence ratings were driven by reading ability or distributed evenly among diverse readers. Seventy fourth-graders with good decoding abilities were administered…

  19. Are Confidence Ratings Test- or Trait-Driven? Individual Differences among High, Average, and Low Comprehenders in Fourth Grade

    Science.gov (United States)

    Kasperski, Ronen; Katzir, Tami

    2013-01-01

    The aim of this study was to examine whether low, average, and high comprehenders (LC, AC, and HC, respectively) differed in their reading self-confidence and bias ratings, and whether confidence ratings were driven by reading ability or distributed evenly among diverse readers. Seventy fourth-graders with good decoding abilities were administered…

  20. Sliding Mode Pulsed Averaging IC Drivers for High Brightness Light Emitting Diodes

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Anatoly Shteynberg, PhD

    2006-08-17

    This project developed new Light Emitting Diode (LED) driver ICs associated with specific (uniquely operated) switching power supplies that optimize performance for High Brightness LEDs (HB-LEDs). The drivers utilize a digital control core with a newly developed nonlinear, hysteretic/sliding mode controller with mixed-signal processing. The drivers are flexible enough to allow both traditional microprocessor interface as well as other options such as “on the fly” adjustment of color and brightness. Some other unique features of the newly developed drivers include • AC Power Factor Correction; • High power efficiency; • Substantially fewer external components should be required, leading to substantial reduction of Bill of Materials (BOM). Thus, the LED drivers developed in this research : optimize LED performance by increasing power efficiency and power factor. Perhaps more remarkably, the LED drivers provide this improved performance at substantially reduced costs compared to the present LED power electronic driver circuits. Since one of the barriers to market penetration for HB-LEDs (in particular “white” light LEDs) is cost/lumen, this research makes important contributions in helping the advancement of SSL consumer acceptance and usage.

  1. Process heat cogeneration using a high temperature reactor

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, Gustavo, E-mail: gustavoalonso3@gmail.com [Instituto Nacional de Investigaciones Nucleares, Carretera Mexico-Toluca s/n, Ocoyoacac, Edo. De Mexico 52750 (Mexico); Instituto Politécnico Nacional, Unidad Profesional Adolfo Lopez Mateos, Ed. 9, Lindavista, D.F. 07300 (Mexico); Ramirez, Ramon [Instituto Nacional de Investigaciones Nucleares, Carretera Mexico-Toluca s/n, Ocoyoacac, Edo. De Mexico 52750 (Mexico); Valle, Edmundo del [Instituto Politécnico Nacional, Unidad Profesional Adolfo Lopez Mateos, Ed. 9, Lindavista, D.F. 07300 (Mexico); Castillo, Rogelio [Instituto Nacional de Investigaciones Nucleares, Carretera Mexico-Toluca s/n, Ocoyoacac, Edo. De Mexico 52750 (Mexico)

    2014-12-15

    Highlights: • HTR feasibility for process heat cogeneration is assessed. • A cogeneration coupling for HTR is proposed and process heat cost is evaluated. • A CCGT process heat cogeneration set up is also assessed. • Technical comparison between both sources of cogeneration is performed. • Economical competitiveness of the HTR for process heat cogeneration is analyzed. - Abstract: High temperature nuclear reactors offer the possibility to generate process heat that could be used in the oil industry, particularly in refineries for gasoline production. These technologies are still under development and none of them has shown how this can be possible and what will be the penalty in electricity generation to have this additional product and if the cost of this subproduct will be competitive with other alternatives. The current study assesses the likeliness of generating process heat from Pebble Bed Modular Reactor to be used for a refinery showing different plant balances and alternatives to produce and use that process heat. An actual practical example is presented to demonstrate the cogeneration viability using the fact that the PBMR is a modular small reactor where the cycle configuration to transport the heat of the reactor to the process plant plays an important role in the cycle efficiency and in the plant economics. The results of this study show that the PBMR would be most competitive when capital discount rates are low (5%), carbon prices are high (>30 US$/ton), and competing natural gas prices are at least 8 US$/mmBTU.

  2. Improvements of high-temperature drying heat pumps

    Energy Technology Data Exchange (ETDEWEB)

    Minea, V. [Hydro-Quebec Research Institute, Laboratoire des technologies de l' energie (LTE), 600, avenue de la Montagne, Shawinigan G9N 7N5 (Canada)

    2010-01-15

    Inadequate integration and/or inappropriate operating parameters of heat pump dryers may lead to troubles as too high/low discharge/suction pressures, low dehumidification efficiency and even mechanical damage to the compressor. This paper will help fix a number of common design errors and/or omissions, and suggests original control methods to avoid undesirable operational incidents and improve overall energy performance of high-temperature drying heat pumps. The scope is to provide normal and safe operating conditions, and thus accelerate the implementation of industrial drying heat pumps. (author)

  3. Analysis of heat transfer under high heat flux nucleate boiling conditions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y.; Dinh, N. [3145 Burlington Laboratories, Raleigh, NC (United States)

    2016-07-15

    Analysis was performed for a heater infrared thermometric imaging temperature data obtained from high heat flux pool boiling and liquid film boiling experiments BETA. With the OpenFOAM solver, heat flux distribution towards the coolant was obtained by solving transient heat conduction of heater substrate given the heater surface temperature data as boundary condition. The so-obtained heat flux data was used to validate them against the state-of-art wall boiling model developed by D. R. Shaver (2015) with the assumption of micro-layer hydrodynamics. Good agreement was found between the model prediction and data for conditions away from the critical heat flux (CHF). However, the data indicate a different heat transfer pattern under CHF, which is not captured by the current model. Experimental data strengthen the notion of burnout caused by the irreversible hot spot due to failure of rewetting. The observation forms a basis for a detailed modeling of micro-layer hydrodynamics under high heat flux.

  4. Analysis of Interrupted Rectangular Microchannel Heat Sink with High Aspect Ratio

    Directory of Open Access Journals (Sweden)

    Harshin Kamal

    2017-01-01

    Full Text Available A computational modelling of microchannel heat sinks with high aspect ratio has been performed to compare the geometrical features in the plane parallel to the heating surface and to determine the optimum configuration for the best heat transfer characteristics. A periodic thermal development of flow can cause significant heat transfer enhancement. A consensus on a particular geometrical configuration that provides the best heat transfer characteristics has not been reached in the literature, although many novel ideas have been proposed recently. Firstly the validity and applicability of microchannel sink modelling is presented followed by an optimization of parameters of interrupted microchannel heat sink. Consequences of the multichannel effect due to the introduction of transverse microchamber are also presented. It has been shown that the average Nusselt number of the microchannel heat sink increases by the introduction of a transverse microchamber with the additional advantage of a lower pressure drop. There exists an optimum width for the transverse microchamber for which the interrupted microchannel heat sink shows optimum characteristics.

  5. Overview of the HiLASE project: high average power pulsed DPSSL systems for research and industry

    Institute of Scientific and Technical Information of China (English)

    M.Divoky; M.Smrz; M.Chyla; P.Sikocinski; P.Severova; O.Novak; J.Huynh; S.S.Nagisetty; T.Miura; J.Pila; O.Slezak; M.Sawicka; V.Jambunathan; J.Vanda; A.Endo; A.Lucianetti; D.Rostohar; P.D.Mason; P.J.Phillips; K.Ertel; S.Banerjee; C.Hernandez-Gomez; J.L.Collier; T.Mocek

    2014-01-01

    An overview of the Czech national R&D project HiLASE(High average power pulsed laser) is presented. The project focuses on the development of advanced high repetition rate, diode pumped solid state laser(DPSSL) systems with energies in the range from mJ to 100 J and repetition rates in the range from 10 Hz to 100 kHz. Some applications of these lasers in research and hi-tech industry are also presented.

  6. Optical Fibre Beam Delivery of High Average Power NEODYMIUM:YAG Laser Radiation

    Science.gov (United States)

    Boechat, Alvaro A. P.

    Available from UMI in association with The British Library. This thesis presents a study of the waveguiding properties of large core (200-1000mum core diameter), relatively short length (5-50m) multimode optical fibres used for delivery of Nd:YAG laser radiation at a wavelength of 1.06mum. A major objective of the study was to provide design information for beam delivery systems used in high power materials processing application. Experimental and theoretical investigation of the optical losses produced by bending the fibre lead to a model which can be used to predict the magnitude of the bend loss as a function of launching conditions, bend geometry and fibre parameters. The study confirms the importance of using large numerical aperture, small core diameter fibres to minimise losses. It has been shown that the beam output near field profile from a fibre is a function of the launching conditions. Theoretical and experimental study of the effect for both step and graded index fibres is presented. Geometric optics and phase space theory was used to develop a model in which a relationship between input and output beam quality from a graded index fibre was established. The results showed that there is an optimum launching condition for which the beam quality may be preserved for fibres with quadratic index profiles. The effect of curvature induced mode coupling on beam quality has been studied experimentally, and compared with intrinsic mode coupling effects. The study was supported by the development of a simple theoretical mode coupling model. Finally, a new monitoring technique for beam delivery systems was developed, based on detection of power in the fibre cladding. Applications include determining laser -fibre coupling efficiency, fibre integrity monitoring, and providing real time process information.

  7. High-frequency supersonic heating of hydrogen for propulsion

    Energy Technology Data Exchange (ETDEWEB)

    Bonneville, Jacques M.

    1963-03-15

    The possibility of increasing the specific impulse of hydrogen by supersonic heating is shown on the basis of thermodynamics. The application of high-frequency electric fields to heat the gas permits a control over the heating rates in the nozzle, and results in a reduction in energy losses to walls, electrodes, etc. The efficiencies of the various energy transfer processes are considered in some detail. A simple process of expansion and heating is presented. Results of calculations of heat transfer rates to the nozzle wall are given. A consistent set of electron densities and electric fields are also calculated and presented. Some qualitative results of experimental work previously carried out are included. It is concluded that the process should increase the specific impulse of hydrogen appreciably, in a reasonably efficient manner, and that further experimental work is indicated. (auth)

  8. High average power and energy microsecond pulse generation from an erbium-doped fluoride fiber MOPA system.

    Science.gov (United States)

    Luo, Hongyu; Li, Jianfneg; Xie, Jitao; Zhai, Bo; Wei, Chen; Liu, Yong

    2016-12-12

    We reported a high average power and energy microsecond pulse erbium-doped fluoride fiber MOPA system centered at 2786.8 nm. The master oscillator was a passively Q-switched erbium-doped fluoride fiber laser based on SESAM in a linear cavity. Then a one-stage erbium-doped fluoride fiber amplifier was used to boost its average output power to 4.2 W and pulse energy to 58.87 μJ. The pulse duration and repetition rate were 2.29 µs and 71.73 kHz, respectively. To the best of our knowledge, the achieved average output power and pulse energy are the recorded levels for the passively Q-switched fiber lasers at 3 μm wavelength region.

  9. The Effect of High School Socioeconomic Status on the Predictive Validity of SAT Scores and High School Grade-Point Average

    Science.gov (United States)

    Zwick, Rebecca; Himelfarb, Igor

    2011-01-01

    Research has often found that, when high school grades and SAT scores are used to predict first-year college grade-point average (FGPA) via regression analysis, African-American and Latino students, are, on average, predicted to earn higher FGPAs than they actually do. Under various plausible models, this phenomenon can be explained in terms of…

  10. Numerical prediction of nucleate pool boiling heat transfer coefficient under high heat fluxes

    Directory of Open Access Journals (Sweden)

    Pezo Milada L.

    2016-01-01

    Full Text Available This paper presents CFD (Computational Fluid Dynamics approach to prediction of the heat transfer coefficient for nucleate pool boiling under high heat fluxes. Three-dimensional numerical simulations of the atmospheric saturated pool boiling are performed. Mathematical modelling of pool boiling requires a treatment of vapor-liquid two-phase mixture on the macro level, as well as on the micro level, such as bubble growth and departure from the heating surface. Two-phase flow is modelled by the two-fluid model, which consists of the mass, momentum and energy conservation equations for each phase. Interface transfer processes are calculated by the closure laws. Micro level phenomena on the heating surface are modelled with the bubble nucleation site density, the bubble resistance time on the heating wall and with the certain level of randomness in the location of bubble nucleation sites. The developed model was used to determine the heat transfer coefficient and results of numerical simulations are compared with available experimental results and several empirical correlations. A considerable scattering of the predictions of the pool boiling heat transfer coefficient by experimental correlations is observed, while the numerically predicted values are within the range of results calculated by well-known Kutateladze, Mostinski, Kruzhilin and Rohsenow correlations. The presented numerical modeling approach is original regarding both the application of the two-fluid two-phase model for the determination of heat transfer coefficient in pool boiling and the defined boundary conditions at the heated wall surface. [Projekat Ministarstva nauke Republike Srbije, br. 174014

  11. High heat transfer oxidizer heat exchanger design and analysis. [RL10-2B engine

    Science.gov (United States)

    Kmiec, Thomas D.; Kanic, Paul G.; Peckham, Richard J.

    1987-01-01

    The RL10-2B engine, a derivative of the RL10, is capable of multimode thrust operation. This engine operates at two low thrust levels: tank head idle (THI), which is approximately 1 to 2% of full thrust, and pumped idle (PI), which is 10% of full thrust. Operation at THI provides vehicle propellant settling thrust and efficient engine thermal conditioning; PI operation provides vehicle tank pre-pressurization and maneuver thrust for low-g deployment. Stable combustion of the RL10-2B engine during the low thrust operating modes can be accomplished by using a heat exchanger to supply gaseous oxygen to the propellant injector. The oxidizer heat exchanger (OHE) vaporizes the liquid oxygen using hydrogen as the energy source. The design, concept verification testing and analysis for such a heat exchanger is discussed. The design presented uses a high efficiency compact core to vaporize the oxygen, and in the self-contained unit, attenuates any pressure and flow oscillations which result from unstable boiling in the core. This approach is referred to as the high heat transfer design. An alternative approach which prevents unstable boiling of the oxygen by limiting the heat transfer is referred to as the low heat transfer design and is reported in Pratt & Whitney report FR-19135-2.

  12. Heat capacity measurements on high T sub c superconductors

    CERN Document Server

    Oezcan, S

    1998-01-01

    temperature interval. The phase transition jump increases with the increasing of oxygen amount in the CuO sub 2 layers. The hight of the jump is varying from 1.5% to 3.5% of the total specific heat which is the nature of the bulk superconductivity. The small coherence length increases fluctuation effects and also causes the dependence of superconducting properties on structural defects. The fluctuation effects on the heat capacity of YBCO is investigated on the sample that shows clear superconducting properties. In this work, a heat capacity measurement system which has high sensitivity and reproducibility designed and constructed. The investigation of the effect of oxygen stoichiometry on the superconducting properties of high T sub c superconductors was aimed. For this purpose electrical resistivity, magnetic susceptibility and heat capacity experiment were performed. The constructed system is a computerized adiabatic calorimeter which has temperature resolution of about 0.1 mk and operates in the temperatu...

  13. Process Simulating of Heat Transfer in High-temperature Thermocouples

    OpenAIRE

    Atroshenko Yuliana K.; Bychkova Alena A.

    2015-01-01

    Numerical research of integral characteristics of process of heattransfer in sensitive elements of R, A and B types thermocouples in case of measurement of high temperatures (more than 900 K) is executed. Theoretical dependences of minimum necessary duration of heating up of the thermocouple on value of temperature on boundary of a sensitive element are received. It is shown the thermocouple of R type requires bigger time of heating for obtaining satisfactory accuracy of measurements. Tempera...

  14. High heat flux engineering in solar energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Cameron, C.P.

    1993-07-01

    Solar thermal energy systems can produce heat fluxes in excess of 10,000 kW/m{sup 2}. This paper provides an introduction to the solar concentrators that produce high heat flux, the receivers that convert the flux into usable thermal energy, and the instrumentation systems used to measure flux in the solar environment. References are incorporated to direct the reader to detailed technical information.

  15. Computations of longitudinal electron dynamics in the recirculating cw RF accelerator-recuperator for the high average power FEL

    Science.gov (United States)

    Sokolov, A. S.; Vinokurov, N. A.

    1994-03-01

    The use of optimal longitudinal phase-energy motion conditions for bunched electrons in a recirculating RF accelerator gives the possibility to increase the final electron peak current and, correspondingly, the FEL gain. The computer code RECFEL, developed for simulations of the longitudinal compression of electron bunches with high average current, essentially loading the cw RF cavities of the recirculator-recuperator, is briefly described and illustrated by some computational results.

  16. High average power picosecond pulse and supercontinuum generation from a thulium-doped, all-fiber amplifier.

    Science.gov (United States)

    Liu, Jiang; Xu, Jia; Liu, Kun; Tan, Fangzhou; Wang, Pu

    2013-10-15

    We demonstrate a high-power, picosecond, thulium-doped, all-fiber master oscillator power amplifier with average power of 120.4 W. The compact fiber oscillator is carefully designed with high repetition rate for the purpose of overcoming the detrimental effects of fiber nonlinearity in the later fiber amplifiers. The pulse duration of 16 ps at 333.75 MHz repetition rate results in a peak power of 22.5 kW in the final fiber power amplifier. To the best of our knowledge, this is the first demonstration of average power exceeding 100 W from an ultrashort pulse laser at 2 μm wavelength. On the other hand, by decreasing the fiber oscillator repetition rate and pulse duration for enhancing the fiber nonlinearity effects, we also demonstrate a high-power supercontinuum source with average power of 36 W from 1.95 μm to beyond 2.4 μm in the final fiber power amplifier.

  17. Effects of Visible and Invisible Hyperlinks on Vocabulary Acquisition and Reading Comprehension for High- and Average-Foreign Language Achievers

    Directory of Open Access Journals (Sweden)

    Ofelia R. Nikolova

    2004-12-01

    Full Text Available This study investigated the effects of visible and invisible links for annotated words in a computer module for learning French on the vocabulary acquisition and reading comprehension of two types of students – high – and average-achievers. Two hundred and sixty four second-semester students of French were identified as high- or average-achievers. Each type of students was then randomly assigned to two groups – with visible or invisible hyperlinks. All students were instructed to read a short passage in French (181 words for general comprehension and allowed to consult the annotated words (made visible by bold face for the visible links group as much as they needed. The students took a vocabulary pretest and an immediate and delayed (two weeks vocabulary and reading comprehension posttest. The results of the study showed that average- achievers benefited more from the visible links for vocabulary acquisition and reading comprehension than high-achievers. The results are discussed in light of second language acquisition and gifted-student theories and suggestions for future research are made.

  18. Pressurized Recuperator For Heat Recovery In Industrial High Temperature Processes

    Directory of Open Access Journals (Sweden)

    Gil S.

    2015-09-01

    Full Text Available Recuperators and regenerators are important devices for heat recovery systems in technological lines of industrial processes and should have high air preheating temperature, low flow resistance and a long service life. The use of heat recovery systems is particularly important in high-temperature industrial processes (especially in metallurgy where large amounts of thermal energy are lost to the environment. The article presents the process design for a high efficiency recuperator intended to work at high operating parameters: air pressure up to 1.2 MPa and temperature of heating up to 900°C. The results of thermal and gas-dynamic calculations were based on an algorithm developed for determination of the recuperation process parameters. The proposed technical solution of the recuperator and determined recuperation parameters ensure its operation under maximum temperature conditions.

  19. Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers

    Science.gov (United States)

    Tu, Y. D.; Wang, R. Z.; Ge, T. S.; Zheng, X.

    2017-01-01

    Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8-3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump’s efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications.

  20. Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers

    Science.gov (United States)

    Tu, Y. D.; Wang, R. Z.; Ge, T. S.; Zheng, X.

    2017-01-01

    Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8–3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump’s efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications. PMID:28079171

  1. Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers.

    Science.gov (United States)

    Tu, Y D; Wang, R Z; Ge, T S; Zheng, X

    2017-01-12

    Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8-3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump's efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications.

  2. High-repetition rate industrial TEA CO2 laser with average output power of 1.5 kW

    Science.gov (United States)

    Wan, Chongyi; Liu, Shiming; Zhou, Jinwen; Qi, Jilan; Yang, Xiaola; Wu, Jin; Tan, Rongqing; Wang, Lichun; Mei, Qichu

    1995-03-01

    High power high repetition rate TEA CO2 laser has potential importance in material processing such as shock hardening, glazing, drilling, welding, and cutting for high damage threshold materials, as well as in chemical reaction and isotope separation. This paper describes a transverse-flow closed-cycle UV-preionized TEA CO2 laser with peak pulse power of 20 MW, maximum average power of 1.5 KW at repetition rate of 300 HZ. The laser has compact constructure of gas flow circulation system using tangential fans. With addition of small amounts of H2 and CO to the normal CO2-N2-He gas mixture, one filling sealed operating lifetime is up to millions of pulses. A novel spark gap switch has been developed for very high repetition rate laser discharge in the condition of high pulse power.

  3. Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation

    Science.gov (United States)

    Daryabeigi, Kamran; Cunnington, George R.; Knutson, Jeffrey R.

    2012-01-01

    Combined radiation and conduction heat transfer through a high-temperature, high-porosity, rigid multiple-fiber fibrous insulation was modeled using a thermal model previously used to model heat transfer in flexible single-fiber fibrous insulation. The rigid insulation studied was alumina enhanced thermal barrier (AETB) at densities between 130 and 260 kilograms per cubic meter. The model consists of using the diffusion approximation for radiation heat transfer, a semi-empirical solid conduction model, and a standard gas conduction model. The relevant parameters needed for the heat transfer model were estimated from steady-state thermal measurements in nitrogen gas at various temperatures and environmental pressures. The heat transfer modeling methodology was evaluated by comparison with standard thermal conductivity measurements, and steady-state thermal measurements in helium and carbon dioxide gases. The heat transfer model is applicable over the temperature range of 300 to 1360 K, pressure range of 0.133 to 101.3 x 10(exp 3) Pa, and over the insulation density range of 130 to 260 kilograms per cubic meter in various gaseous environments.

  4. Analysis of frozen startup of high-temperature heat pipes and three-dimensional modeling of block-heated heat pipes

    Science.gov (United States)

    Faghri, Amir

    1991-11-01

    The use of high-temperature heat pipes has been proposed for cooling the leading edges and nose cones of re-entry vehicles, rail guns, and laser mirrors, as well as for the thermal management of future hypersonic vehicle structures. The startup behavior of high temperature heat pipes from the frozen state was investigated both numerically and experimentally for various heat loads and input locations. A high temperature sodium/stainless steel heat pipe with multiple heat sources and sinks was fabricated, processed, and tested. A numerical simulation of the transient heat pipe performance including the vapor region, wick structure, and the heat pipe wall is given. Furthermore, experimental and numerical analyses of several operating parameters of a low-temperature copper-water heat pipe under uniform circumferential heating and block heating has been performed. Finally, a numerical analysis of transient heat pipe performance including nonconventional heat pipes with nonuniform heat distributions is presented. Numerical calculations were then made for a leading edge heat pipe with localized high heat fluxes.

  5. Theoretical and Numerical Study of Heat Transfer Deterioration in High Performance Light Water Reactor

    Directory of Open Access Journals (Sweden)

    David Palko

    2008-01-01

    Full Text Available A numerical investigation of the heat transfer deterioration (HTD phenomena is performed using the low-Re k-ω turbulence model. Steady-state Reynolds-averaged Navier-Stokes equations are solved together with equations for the transport of enthalpy and turbulence. Equations are solved for the supercritical water flow at different pressures, using water properties from the standard IAPWS (International Association for the Properties of Water and Steam tables. All cases are extensively validated against experimental data. The influence of buoyancy on the HTD is demonstrated for different mass flow rates in the heated pipes. Numerical results prove that the RANS low-Re turbulence modeling approach is fully capable of simulating the heat transfer in pipes with the water flow at supercritical pressures. A study of buoyancy influence shows that for the low-mass flow rates of coolant, the influence of buoyancy forces on the heat transfer in heated pipes is significant. For the high flow rates, buoyancy influence could be neglected and there are clearly other mechanisms causing the decrease in heat transfer at high coolant flow rates.

  6. High-Thermal Conductive Coating Used on Metal Heat Exchanger

    Institute of Scientific and Technical Information of China (English)

    李静; 梁剧; 刘业明

    2014-01-01

    Based on modified silicon polyester resin in addition to several functional fillers such as corro-sion-resistant fillers, heat-resistant fillers and thermal conductive fillers, a high thermal conductive coating can be made. On the basis of boronnitride (BN) and aluminum nitride (AIN) used as thermal conductive fillers and by means of the testing system of hot disk and heat transfer experiment, researches on the varieties of thermal conduc-tive fillers and the effects of the contents of high-thermal conductive coating have been done, which shows that the thermal conductivity of coating increases with the increase of the quality fraction and the coefficient of thermal conductivity of the thermal conductive fillers of coating. With guaranteeing better heat resistance, stronger corro-sion resistance and adhesive force, the coefficient of coating can reach a level as high as 3 W·m-1·K-1.

  7. High Harmonic Fast Wave heating and current drive for NSTX

    Science.gov (United States)

    Robinson, J. A.; Majeski, R.; Hosea, J.; Menard, J.; Ono, M.; Phillips, C. K.; Wilson, J. R.; Wright, J.; Batchelor, D. B.; Carter, M. D.; Jaeger, E. F.; Ryan, P.; Swain, D.; Mau, T. K.; Chiu, S. C.; Smithe, D.

    1997-11-01

    Heating and noninductive current drive in NSTX will initially use 6 MW of rf power in the high harmonic fast wave (HHFW) regime. We present numerical modelling of HHFW heating and current drive in NSTX using the PICES, CURRAY, FISIC, and METS95 codes. High electron β during the discharge flattop in NSTX is predicted to result in off-axis power deposition and current drive. However, reductions in the trapped electron fraction (due also to high β effects) are predicted to result in adequate current drive efficiency, with ~ 400 - 500 kA of noninductive current driven. Sufficient per-pass absorption (>10%) to ensure effective electron heating is also expected for the startup plasma. Present plans call for a single twelve strap antenna driven by six FMIT transmitters operating at 30 MHz. The design for the antenna and matching system will also be discussed.

  8. Liquid metal heat sink for high-power laser diodes

    Science.gov (United States)

    Vetrovec, John; Litt, Amardeep S.; Copeland, Drew A.; Junghans, Jeremy; Durkee, Roger

    2013-02-01

    We report on the development of a novel, ultra-low thermal resistance active heat sink (AHS) for thermal management of high-power laser diodes (HPLD) and other electronic and photonic components. AHS uses a liquid metal coolant flowing at high speed in a miniature closed and sealed loop. The liquid metal coolant receives waste heat from an HPLD at high flux and transfers it at much reduced flux to environment, primary coolant fluid, heat pipe, or structure. Liquid metal flow is maintained electromagnetically without any moving parts. Velocity of liquid metal flow can be controlled electronically, thus allowing for temperature control of HPLD wavelength. This feature also enables operation at a stable wavelength over a broad range of ambient conditions. Results from testing an HPLD cooled by AHS are presented.

  9. Edge-facet pumped, multi-aperture, thin-disk laser geometry for very high average power output scaling

    Energy Technology Data Exchange (ETDEWEB)

    Zapata, Luis E.

    2004-12-21

    The average power output of a laser is scaled, to first order, by increasing the transverse dimension of the gain medium while increasing the thickness of an index matched light guide proportionately. Strategic facets cut at the edges of the laminated gain medium provide a method by which the pump light introduced through edges of the composite structure is trapped and passes through the gain medium repeatedly. Spontaneous emission escapes the laser volume via these facets. A multi-faceted disk geometry with grooves cut into the thickness of the gain medium is optimized to passively reject spontaneous emission generated within the laser material, which would otherwise be trapped and amplified within the high index composite disk. Such geometry allows the useful size of the laser aperture to be increased, enabling the average laser output power to be scaled.

  10. Screening for hepatitis C in average and high-risk populations of Qatar using rapid point-of-care testing

    Science.gov (United States)

    Al Kaabi, Saad; John, Anil K; Al Dweik, Nazeeh; Ullah Wani, Hameed; Babu Thandassary, Ragesh; Derbala, Moutaz F; Al Ejji, Khalid; Sultan, Khaleel; Pasic, Fuad; Al Mohannadi, Munnera; Yacoub, Rafae; Butt, Mohd Tariq; Singh, Rajvir

    2015-01-01

    Background Screening for hepatitis C has been found to be beneficial in high-risk individuals and ‘baby boomers’. Objective Our aim was to screen for hepatitis C in average and high-risk individuals and compare the disease characteristics and response to treatment among the screened group (SG) and non-screened group (NSG). Method Community-based screening for hepatitis C was done in the average and high-risk populations of Qatar. Screening was done using rapid point-of-care testing. All patients with stage 1 fibrosis on liver biopsy were treated with pegylated interferon and ribavirin. Results In total, 13,704 people were screened and 272 (2%, 95% CI (1.8–2.2%) had positive antibodies to hepatitis C. During the same period, 237 non-screened patients (NSG) with hepatitis C were referred for treatment. Alanine and aspartate aminotransferases (ALT, AST) and overall fibrosis were significantly lower in the SG as compared with the NSG (p = 0.04, 0.04 and 0.01, respectively). The response to treatment was similar in the SG as compared with the NSG (sustained viral response 61.7 % versus 69.1%, p = 0.55). Average-risk patients had significantly lower ALT levels (p = 0.04) but had similar response to treatment as the high-risk individuals (sustained viral response 63.2 % versus 61%, p = 0.87). Conclusion Screening detects hepatitis C with lesser fibrosis but does not result in better response to pegylated interferon and ribavirin as compared with non-screened patients. PMID:26279845

  11. Transient pool boiling heat transfer due to increasing heat inputs in subcooled water at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, K. [Kobe Univ. of Mercantile Marine (Japan); Shiotsu, M.; Sakurai, A. [Kyoto Univ. (Japan)

    1995-09-01

    Understanding of transient boiling phenomenon caused by increasing heat inputs in subcooled water at high pressures is necessary to predict correctly a severe accident due to a power burst in a water-cooled nuclear reactor. Transient maximum heat fluxes, q{sub max}, on a 1.2 mm diameter horizontal cylinder in a pool of saturated and subcooled water for exponential heat inputs, q{sub o}e{sup t/T}, with periods, {tau}, ranging from about 2 ms to 20 s at pressures from atmospheric up to 2063 kPa for water subcoolings from 0 to about 80 K were measured to obtain the extended data base to investigate the effect of high subcoolings on steady-state and transient maximum heat fluxes, q{sub max}. Two main mechanisms of q{sub max} exist depending on the exponential periods at low subcoolings. One is due to the time lag of the hydrodynamic instability which starts at steady-state maximum heat flux on fully developed nucleate boiling (FDNB), and the other is due to the heterogenous spontaneous nucleations (HSN) in flooded cavities which coexist with vapor bubbles growing up from active cavities. The shortest period corresponding to the maximum q{sub max} for long period range belonging to the former mechanism becomes longer and the q{sub max}mechanism for long period range shifts to that due the HSN on FDNB with the increase of subcooling and pressure. The longest period corresponding to the minimum q{sub max} for the short period range belonging to the latter mechanism becomes shorter with the increase in saturated pressure. On the contrary, the longest period becomes longer with the increase in subcooling at high pressures. Correlations for steady-state and transient maximum heat fluxes were presented for a wide range of pressure and subcooling.

  12. A satellite snow depth multi-year average derived from SSM/I for the high latitude regions

    Science.gov (United States)

    Biancamaria, S.; Mognard, N.M.; Boone, A.; Grippa, M.; Josberger, E.G.

    2008-01-01

    The hydrological cycle for high latitude regions is inherently linked with the seasonal snowpack. Thus, accurately monitoring the snow depth and the associated aerial coverage are critical issues for monitoring the global climate system. Passive microwave satellite measurements provide an optimal means to monitor the snowpack over the arctic region. While the temporal evolution of snow extent can be observed globally from microwave radiometers, the determination of the corresponding snow depth is more difficult. A dynamic algorithm that accounts for the dependence of the microwave scattering on the snow grain size has been developed to estimate snow depth from Special Sensor Microwave/Imager (SSM/I) brightness temperatures and was validated over the U.S. Great Plains and Western Siberia. The purpose of this study is to assess the dynamic algorithm performance over the entire high latitude (land) region by computing a snow depth multi-year field for the time period 1987-1995. This multi-year average is compared to the Global Soil Wetness Project-Phase2 (GSWP2) snow depth computed from several state-of-the-art land surface schemes and averaged over the same time period. The multi-year average obtained by the dynamic algorithm is in good agreement with the GSWP2 snow depth field (the correlation coefficient for January is 0.55). The static algorithm, which assumes a constant snow grain size in space and time does not correlate with the GSWP2 snow depth field (the correlation coefficient with GSWP2 data for January is - 0.03), but exhibits a very high anti-correlation with the NCEP average January air temperature field (correlation coefficient - 0.77), the deepest satellite snow pack being located in the coldest regions, where the snow grain size may be significantly larger than the average value used in the static algorithm. The dynamic algorithm performs better over Eurasia (with a correlation coefficient with GSWP2 snow depth equal to 0.65) than over North America

  13. Optimal configuration for a finite high-temperature source heat engine cycle with the complex heat transfer law

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The optimal configuration of a heat engine operating between a finite high-temperature source and an infinite low-temperature reservoir is derived by using finite time thermodynamics based on a complex heat transfer law,including Newtonian heat transfer law,linear phenomenological heat transfer law,radiative heat transfer law,Dulong-Petit heat transfer law,generalized convective heat transfer law and generalized radiative heat transfer law,q ∝(△T n). In the engine model the only irreversibility of finite rate heat transfer is considered. The optimal relation between the power output and efficiency of the heat engine is also derived by using an equivalent temperature of the hot reservoir. The obtained results include those obtained in recent literature and can provide some theoretical guidance for the designs of practical engines.

  14. Optimal configuration for a finite high-temperature source heat engine cycle with the complex heat transfer law

    Institute of Scientific and Technical Information of China (English)

    LI Jun; CHEN LinGen; SUN FengRui

    2009-01-01

    The optimal configuration of a heat engine operating between a finite high-temperature source and an infinite low-temperature reservoir is derived by using finite time thermodynamics based on a complex heat transfer law, including Newtonian heat transfer law, linear phenomenological heat transfer law, radiative heat transfer law, Dulong-Petit heat transfer law, generalized convective heat transfer law and generalized radiative heat transfer law, q∝ (△Tn). In the engine model the only irreversibility of finite rate heat transfer is considered. The optimal relation between the power output and efficiency of the heat engine is also derived by using an equivalent temperature of the hot reservoir. The obtained re-sults include those obtained in recent literature and can provide some theoretical guidance for the de-signs of practical engines.

  15. Scaling of high-field transport and localized heating in graphene transistors.

    Science.gov (United States)

    Bae, Myung-Ho; Islam, Sharnali; Dorgan, Vincent E; Pop, Eric

    2011-10-25

    We use infrared thermal imaging and electrothermal simulations to find that localized Joule heating in graphene field-effect transistors on SiO(2) is primarily governed by device electrostatics. Hot spots become more localized (i.e., sharper) as the underlying oxide thickness is reduced, such that the average and peak device temperatures scale differently, with significant long-term reliability implications. The average temperature is proportional to oxide thickness, but the peak temperature is minimized at an oxide thickness of ∼90 nm due to competing electrostatic and thermal effects. We also find that careful comparison of high-field transport models with thermal imaging can be used to shed light on velocity saturation effects. The results shed light on optimizing heat dissipation and reliability of graphene devices and interconnects.

  16. Development activities of the high heat flux scraper element

    Energy Technology Data Exchange (ETDEWEB)

    Boscary, J., E-mail: jean.boscary@ipp.mpg.de [Max Planck Institute for Plasma Physics, Garching (Germany); Lore, J.; Lumsdaine, A. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Maier, M. [Max Planck Institute for Plasma Physics, Garching (Germany); McGinnis, D. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Peacock, A.; Tretter, J. [Max Planck Institute for Plasma Physics, Garching (Germany)

    2015-10-15

    The function of the high heat flux scraper element is to reduce the heat loads on the element ends of the actively cooled divertor of Wendelstein 7-X. The scraper element is actively water cooled to remove up to 550 kW steady state power load, with localized heat fluxes as high as 20 MW/m{sup 2}. Its surface area, 0.17 m{sup 2}, is contoured to optimally intercept both upstream and downstream particle fluxes. The plasma facing surface is made of 24 individual scraper fingers based on the monoblock technology. Each scraper finger is 247 mm long and 28 mm wide and has 13 monoblocks made of CFC NB31 bonded by hot isostatic pressing onto a CuCrZr cooling tube equipped with a copper twisted tape. Development activities, described here, include the design and fabrication of prototypes to validate the different technologies selected for the scraper element design to prepare a possible production.

  17. High-temperature industrial heat pump. Management plan

    Energy Technology Data Exchange (ETDEWEB)

    Deckman, G

    1979-03-12

    The management plan for the development and demonstration of a high-temperature industrial heat pump for milk drying is presented. Section 2 describes the overall objective, technical approach, and program scope for development and demonstration of a heat pump system for use in an existing milk drying operation. The high temperature industrial heat pump program organization, its relationships to higher-level AiResearch organizations, subcontractor relationships, and personnel responsibilities are discussed in Section 3. The program management and control functions and data management techniques are described in Section 4. The activity for each work breakdown structure is described in Section 5. The program schedule is schematically shown in Section 6 and cost management reports are described in Section 7.

  18. Predicting freeboard heat transfer by using empirical correlations in high temperature fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Biyikli, Suleyman [Okan University Tuzla Kampusu, Faculty of Engineering and Architecture (Turkey)], email: suleyman.biyikli@okan.edu.tr

    2011-07-01

    This article investigates the heat transfer characteristics for horizontal tubes in a freeboard region of high temperature fluidized beds. The freeboard entrainment heights are calculated by using empirical correlations described in detail and used in estimating the heat transfer coefficients from a horizontal tube occurring by radiation, gas convection, and particle contact mechanisms in high temperature a fluidized bed combustor. The total average of these coefficients around a horizontal tube carrying water in high temperature fluidized beds can be written as the sum of convective, radiative, and fluidized-particle contact heat transfer coefficients and these correlations are tested against certain published experimental measurements. In full agreement with this data, it was observed that the calculated heat transfer coefficients increased with increasing gas velocity at a given tube elevation and they decreased and approached the values of single-phase gas convection and radiation with increasing tube elevation in the freeboard region while the relative contribution of radiation increases and approaches a constant fraction of total heat transfer.

  19. Design of an L-band normally conducting RF gun cavity for high peak and average RF power

    Science.gov (United States)

    Paramonov, V.; Philipp, S.; Rybakov, I.; Skassyrskaya, A.; Stephan, F.

    2017-05-01

    To provide high quality electron bunches for linear accelerators used in free electron lasers and particle colliders, RF gun cavities operate with extreme electric fields, resulting in a high pulsed RF power. The main L-band superconducting linacs of such facilities also require a long RF pulse length, resulting in a high average dissipated RF power in the gun cavity. The newly developed cavity based on the proven advantages of the existing DESY RF gun cavities, underwent significant changes. The shape of the cells is optimized to reduce the maximal surface electric field and RF loss power. Furthermore, the cavity is equipped with an RF probe to measure the field amplitude and phase. The elaborated cooling circuit design results in a lower temperature rise on the cavity RF surface and permits higher dissipated RF power. The paper presents the main solutions and results of the cavity design.

  20. Plasma wakefield excitation by incoherent laser pulses: a path towards high-average power laser-plasma accelerators

    CERN Document Server

    Benedetti, C; Esarey, E; Leemans, W P

    2014-01-01

    In a laser plasma accelerator (LPA), a short and intense laser pulse propagating in a plasma drives a wakefield (a plasma wave with a relativistic phase velocity) that can sustain extremely large electric fields, enabling compact accelerating structures. Potential LPA applications include compact radiation sources and high energy linear colliders. We propose and study plasma wave excitation by an incoherent combination of a large number of low energy laser pulses (i.e., without constraining the pulse phases). We show that, in spite of the incoherent nature of electromagnetic fields within the volume occupied by the pulses, the excited wakefield is regular and its amplitude is comparable or equal to that obtained using a single, coherent pulse with the same energy. These results provide a path to the next generation of LPA-based applications, where incoherently combined multiple pulses may enable high repetition rate, high average power LPAs.

  1. Heat shock response and mammal adaptation to high elevation (hypoxia)

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaolin; XU Cunshuan; WANG Xiujie; WANG Dongjie; WANG Qingshang; ZHANG Baochen

    2006-01-01

    The mammal's high elevation (hypoxia) adaptation was studied by using the immunological and the molecular biological methods to understand the significance of Hsp (hypoxia) adaptation in the organic high elevation, through the mammal heat shock response. (1) From high elevation to low elevation (natural hypoxia): Western blot and conventional RT-PCR and real-time fluorescence quota PCR were adopted. Expression difference of heat shock protein of 70 (Hsp70) and natural expression of brain tissue of Hsp70 gene was determined in the cardiac muscle tissue among the different elevation mammals (yak). (2)From low elevation to high elevation (hypoxia induction):The mammals (domestic rabbits) from the low elevation were sent directly to the areas with different high elevations like 2300, 3300 and 5000 m above sea level to be raised for a period of 3 weeks before being slaughtered and the genetic inductive expression of the brain tissue of Hsp70 was determined with RT-PCR. The result indicated that all of the mammals at different elevations possessed their heat shock response gene. Hsp70 of the high elevation mammal rose abruptly under stress and might be induced to come into being by high elevation (hypoxia). The speedy synthesis of Hsp70 in the process of heat shock response is suitable to maintain the cells' normal physiological functions under stress. The Hsp70 has its threshold value. The altitude of 5000 m above sea level is the best condition for the heat shock response, and it starts to reduce when the altitude is over 6000 m above sea level. The Hsp70 production quantity and the cell hypoxia bearing capacity have their direct ratio.

  2. Surfaces for high heat dissipation with no Leidenfrost limit

    Science.gov (United States)

    Sajadi, Seyed Mohammad; Irajizad, Peyman; Kashyap, Varun; Farokhnia, Nazanin; Ghasemi, Hadi

    2017-07-01

    Heat dissipation from hot surfaces through cooling droplets is limited by the Leidenfrost point (LFP), in which an insulating vapor film prevents direct contact between the cooling droplet and the hot surface. A range of approaches have been developed to raise this limit to higher temperatures, but the limit still exists. Recently, a surface architecture, decoupled hierarchical structure, was developed that allows the suppression of LFP completely. However, heat dissipation by the structure in the low superheat region was inferior to other surfaces and the structure required an extensive micro/nano fabrication procedure. Here, we present a metallic surface structure with no LFP and high heat dissipation capacity in all temperature ranges. The surface features the nucleate boiling phenomenon independent of the temperature with an approximate heat transfer coefficient of 20 kW m-2 K-1. This surface is developed in a one-step process with no micro/nano fabrication. We envision that this metallic surface provides a unique platform for high heat dissipation in power generation, photonics/electronics, and aviation systems.

  3. High geothermal heat flux measured below the West Antarctic Ice Sheet.

    Science.gov (United States)

    Fisher, Andrew T; Mankoff, Kenneth D; Tulaczyk, Slawek M; Tyler, Scott W; Foley, Neil

    2015-07-01

    The geothermal heat flux is a critical thermal boundary condition that influences the melting, flow, and mass balance of ice sheets, but measurements of this parameter are difficult to make in ice-covered regions. We report the first direct measurement of geothermal heat flux into the base of the West Antarctic Ice Sheet (WAIS), below Subglacial Lake Whillans, determined from the thermal gradient and the thermal conductivity of sediment under the lake. The heat flux at this site is 285 ± 80 mW/m(2), significantly higher than the continental and regional averages estimated for this site using regional geophysical and glaciological models. Independent temperature measurements in the ice indicate an upward heat flux through the WAIS of 105 ± 13 mW/m(2). The difference between these heat flux values could contribute to basal melting and/or be advected from Subglacial Lake Whillans by flowing water. The high geothermal heat flux may help to explain why ice streams and subglacial lakes are so abundant and dynamic in this region.

  4. High-Throughput Laser Peening of Metals Using a High-Average-Power Nd: Glass Laser System

    Energy Technology Data Exchange (ETDEWEB)

    Dane, C.B.; Hackel, L.A.; Halpin, J.; Daly, J.; Harrisson, J.; Harris, J.

    1999-11-01

    Laser shot peening, a surface treatment for metals, is known to induce residual compressive stresses to depths of over 1 mm providing improved component resistance to various forms of failure. Recent information also suggests that thermal relaxation of the laser induced stress is significantly less than that experienced by other forms of surface stressing that involve significantly higher levels of cold work. We have developed a unique solid state laser technology employing Nd:glass amplifier slabs and SBS phase conjugation that enables this process to move into high throughput production processing.

  5. Process Simulating of Heat Transfer in High-temperature Thermocouples

    Directory of Open Access Journals (Sweden)

    Atroshenko Yuliana K.

    2015-01-01

    Full Text Available Numerical research of integral characteristics of process of heattransfer in sensitive elements of R, A and B types thermocouples in case of measurement of high temperatures (more than 900 K is executed. Theoretical dependences of minimum necessary duration of heating up of the thermocouple on value of temperature on boundary of a sensitive element are received. It is shown the thermocouple of R type requires bigger time of heating for obtaining satisfactory accuracy of measurements. Temperature fields in sensitive elements of the specified thermocouples are received. It is shown that distribution of temperature on the thermocouple not linearly and has similar character for the researched thermocouples.

  6. Optical levitation of high purity nanodiamonds in vacuum without heating

    CERN Document Server

    Frangeskou, A C; Gines, L; Mandal, S; Williams, O A; Barker, P F; Morley, G W

    2016-01-01

    Levitated nanodiamonds containing nitrogen vacancy centres in high vacuum are a potential test bed for numerous phenomena in fundamental physics. However, experiments so far have been limited to low vacuum due to heating arising from optical absorption of the trapping laser. We show that milling pure diamond creates nanodiamonds that do not heat up as the optical intensity is raised above 700 GW/m$^2$ below 5 mbar of pressure. This advance now means that the level of attainable vacuum for nanodiamonds in optical dipole traps is no longer temperature limited.

  7. Resistive Wall Heating of the Undulator in High Repetition Rate

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, J; Corlett, J; Emma, P; Wu, J

    2012-05-20

    In next generation high repetition rate FELs, beam energy loss due to resistive wall wakefields will produce significant amount of heat. The heat load for a superconducting undulator (operating at low temperature), must be removed and will be expensive to remove. In this paper, we study this effect in an undulator proposed for a Next Generation Light Source (NGLS) at LBNL. We benchmark our calculations with measurements at the LCLS and carry out detailed parameter studies using beam from a start-to-end simulation. Our preliminarym results suggest that the heat load in the undulator is about 2 W/m or lower with an aperture size of 6 mm for nominal NGLS preliminary design parameters.

  8. Geothermal concept for energy efficient improvement of space heating and cooling in highly urbanized area

    Directory of Open Access Journals (Sweden)

    Vranjes Ana

    2015-01-01

    Full Text Available New Belgrade is a highly urbanized commercial and residential district of Belgrade lying on the alluvial plane of the Sava and the Danube rivers. The groundwater of the area is a geothermal resource that is usable through geothermal heat pumps (GHP. The research has shown that the “heat island effect” affects part of the alluvial groundwater with the average groundwater temperature of about 15.5°C, i.e. 2°C higher than the one in less urbanized surroundings. Based on the measured groundwater temperatures as well as the appraisal of the sustainable aquifer yield, the available thermal power of the resource is estimated to about 29MWt. The increasing urbanization trend of the New Belgrade district implies the growing energy demands that may partly be met by the available groundwater thermal power. Taking into consideration the average apartment consumption of 80 Wm-2, it is possible to heat about 360,000 m2 and with the consumption efficiency of 50 Wm-2, it would be possible to heat over 570,000 m2. Environmental and financial aspects were considered through the substitution of conventional fuels and the reduction of greenhouse gas emission as well as through the optimization of the resource use.

  9. Enhanced flat adenoma detection rate with high definition colonoscopy plus i-scan for average-risk colorectal cancer screening

    Directory of Open Access Journals (Sweden)

    Antonio Rodríguez-D'Jesús

    Full Text Available Background and aim: The usefulness of high definition colonoscopy plus i-scan (HD+i-SCAN for average-risk colorectal cancer screening has not been fully assessed. The detection rate of adenomas and other measurements such as the number of adenomas per colonoscopy and the flat adenoma detection rate have been recognized as markers of colonoscopy quality. The aim of the present study was to compare the diagnostic performance of an HD+i-SCAN with that of standard resolution white-light colonoscope. Methods: This is a retrospective analysis of a prospectively collected screening colonoscopy database. A comparative analysis of the diagnostic yield of an HD+i-SCAN or standard resolution colonoscopy for average-risk colorectal screening was conducted. Results: During the period of study, 155/163 (95.1% patients met the inclusion criteria. The mean age was 56.9 years. Sixty of 155 (39% colonoscopies were performed using a HD+i-SCAN. Adenoma-detection-rates during the withdrawal of the standard resolution versus HD+i-SCAN colonoscopies were 29.5% and 30% (p = n.s.. Adenoma/colonoscopy values for standard resolution versus HD+i-SCAN colonoscopies were 0.46 (SD = 0.9 and 0.72 (SD = 1.3 (p = n.s.. A greater number of flat adenomas were detected in the HD+i-SCAN group (6/60 vs. 2/95 (p < .05. Likewise, serrated adenomas/polyps per colonoscopy were also higher in the HD+i-SCAN group. Conclusions: A HD+i-SCAN colonoscopy increases the flat adenoma detection rate and serrated adenomas/polyps per colonoscopy compared to a standard colonoscopy in average-risk screening population. HD+i-SCAN is a simple, available procedure that can be helpful, even for experienced providers. The performance of HD+i-SCAN and substantial prevalence of flat lesions in our average-risk screening cohort support its usefulness in improving the efficacy of screening colonoscopies.

  10. Mechanical Properties of Heat Affected Zone of High Strength Steels

    Science.gov (United States)

    Sefcikova, K.; Brtnik, T.; Dolejs, J.; Keltamaki, K.; Topilla, R.

    2015-11-01

    High Strength Steels became more popular as a construction material during last decade because of their increased availability and affordability. On the other hand, even though general use of Advanced High Strength Steels (AHSS) is expanding, the wide utilization is limited because of insufficient information about their behaviour in structures. The most widely used technique for joining steels is fusion welding. The welding process has an influence not only on the welded connection but on the area near this connection, the so-called heat affected zone, as well. For that reason it is very important to be able to determine the properties in the heat affected zone (HAZ). This area of investigation is being continuously developed in dependence on significant progress in material production, especially regarding new types of steels available. There are currently several types of AHSS on the world market. Two most widely used processes for AHSS production are Thermo-Mechanically Controlled Processing (TMCP) and Quenching in connection with Tempering. In the presented study, TMCP and QC steels grade S960 were investigated. The study is focused on the changes of strength, ductility, hardness and impact strength in heat affected zone based on the used amount of heat input.

  11. Heating and Life Problem of High Power Density Induction Motor

    Institute of Scientific and Technical Information of China (English)

    李立毅; 崔淑梅; 宋立伟; 胡余生

    2004-01-01

    An induction motor with its speed modulated by frequency features wide transfer speed range, high systematic efficiency, simple structure and long life, and it therefore becomes one of the best driving motors used in electrical vehicles. The present research trend of it is high power, high speed, high efficiency and long life. How to meet the above requirements by using the electromagnetic design, structure design and heat design, becomes a matter that needs to be resolved now. In this paper, the characters of the motor in operation are analyzed, all kinds of factors that relate to life are laid out, its heating and loss are discussed and analyzed.The key reasons affecting the motor life are presented, and different characters of a high induction motor are compared with these of a general induction motor. A design idea is described, that is: we should consider how to improve the efficiency and reliability as well as how to reduce the heating by changing the electromagnet,structure, dissipation and operation of the motor. How to reduce its losses and to improve its dissipation has been presented in the paper.

  12. Iterative Bayesian Model Averaging: a method for the application of survival analysis to high-dimensional microarray data

    Directory of Open Access Journals (Sweden)

    Raftery Adrian E

    2009-02-01

    Full Text Available Abstract Background Microarray technology is increasingly used to identify potential biomarkers for cancer prognostics and diagnostics. Previously, we have developed the iterative Bayesian Model Averaging (BMA algorithm for use in classification. Here, we extend the iterative BMA algorithm for application to survival analysis on high-dimensional microarray data. The main goal in applying survival analysis to microarray data is to determine a highly predictive model of patients' time to event (such as death, relapse, or metastasis using a small number of selected genes. Our multivariate procedure combines the effectiveness of multiple contending models by calculating the weighted average of their posterior probability distributions. Our results demonstrate that our iterative BMA algorithm for survival analysis achieves high prediction accuracy while consistently selecting a small and cost-effective number of predictor genes. Results We applied the iterative BMA algorithm to two cancer datasets: breast cancer and diffuse large B-cell lymphoma (DLBCL data. On the breast cancer data, the algorithm selected a total of 15 predictor genes across 84 contending models from the training data. The maximum likelihood estimates of the selected genes and the posterior probabilities of the selected models from the training data were used to divide patients in the test (or validation dataset into high- and low-risk categories. Using the genes and models determined from the training data, we assigned patients from the test data into highly distinct risk groups (as indicated by a p-value of 7.26e-05 from the log-rank test. Moreover, we achieved comparable results using only the 5 top selected genes with 100% posterior probabilities. On the DLBCL data, our iterative BMA procedure selected a total of 25 genes across 3 contending models from the training data. Once again, we assigned the patients in the validation set to significantly distinct risk groups (p

  13. An Intercomparison of Techniques to Determine the Area-Averaged Latent Heat Flux from Individual in Situ Observations: A remote Sensing Approach Using the European Field Experiment in a Desertification-Threatened Area Data

    Science.gov (United States)

    Pelgrum, H.; Bastiaanssen, W. G. M.

    1996-04-01

    A knowledge of the area-averaged latent heat flux is necessary to validate large-scale model predictions of heat fluxes over heterogeneous land surfaces. This paper describes different procedures to obtain as a weighted average of ground-based observations. The weighting coefficients are obtained from remote sensing measurements. The remote sensing data used in this study consist of a Landsat thematic mapper image of the European Field Experiment in a Desertification-Threatened Area (EFEDA) grid box in central Spain, acquired on June 12, 1991. A newly developed remote sensing algorithm, the surface energy balance for land algorithm (SEBAL), solves the energy budget on a pixel-by-pixel basis. From the resulting frequency distribution of the latent heat flux, the area-averaged latent heat flux was calculated as = 164 W m-2. This method was validated with field measurements of latent heat flux, sensible heat flux, and soil moisture. In general, the SEBAL-derived output compared well with field measurements. Two other methods for retrieval of weighting coefficients were tested against SEBAL. The second method combines satellite images of surface temperature, surface albedo, and normalized difference vegetation index (NDVI) into an index on a pixel-by-pixel basis. After inclusion of ground-based measurements of the latent heat flux, a linear relationship between the index and the latent heat flux was established. This relationship was used to map the latent heat flux on a pixel-by-pixel basis, resulting in = 194 W m-2. The third method makes use of a supervised classification of the thematic mapper image into eight land use classes. An average latent heat flux was assigned to each class by using field measurements of the latent heat flux. According to the percentage of occurrence of each class in the image, was calculated as 110 W m-2. A weighting scheme was produced to make an estimation of possible from in situ observations. The weighting scheme contained a

  14. Investigation of cognitive abilities related to reading and spelling in Korean: readers with high, average, and low skill levels.

    Science.gov (United States)

    Park, Hyun-Rin; Uno, Akira

    2012-11-01

    In this study, we investigated the characteristics of cognitive abilities as predictors of Korean reading and spelling ability, and the characteristics of the cognition of reading difficulty in Korean. In 103 Korean third-grade children, we tested ability to read and spell, nonverbal intelligence, vocabulary size, phonological cognitive processing, visual cognitive processing, and naming speed. Our results indicated that receptive vocabulary, phoneme awareness, and naming speed served as factors for predicting reading test score; receptive vocabulary served as a factor for predicting spelling test score. We found that low reading-level groups had significantly slower performance on the naming speed task and lower scores on the receptive vocabulary test, as compared with the other groups (average and high reading-level groups). The present results have implications concerning useful tasks for screening for Korean poor readers. Copyright © 2012 John Wiley & Sons, Ltd.

  15. Status of the High Average Power Diode-Pumped Solid State Laser Development at HiLASE

    Directory of Open Access Journals (Sweden)

    Ondřej Novák

    2015-09-01

    Full Text Available An overview of the latest developments of kilowatt-level diode pumped solid state lasers for advanced applications at the HiLASE Centre is presented. An overview of subcontracted and in-house-developed laser beamlines is presented. The aim of development is to build kW-class beamlines delivering picosecond pulses between 1- and 100-kHz repetition rates and high-energy nanosecond pulses at 10 Hz. The picosecond beamlines are based on Yb:YAG thin-disk amplifiers and chirped pulse amplification. The current status of the beamlines’ performance is reported. The advantages of zero-phonon line and pulsed pumping are demonstrated with respect to efficiency, thin disk temperature and beam quality. New diagnostics methods supporting the high average power lasers’ development, such as the high-resolution spectroscopy of Yb-doped materials, in situ thin disk deformation measurements, single-shot M2 measurement, realization of wavefront correction by a deformable mirror and the laser performance of a new mixed garnet ceramics, are described. The energetic, thermal and fluid-mechanical numerical modeling for the optimization of the multi-slab amplifiers is also described.

  16. Combined Heat Transfer in High-Porosity High-Temperature Fibrous Insulations: Theory and Experimental Validation

    Science.gov (United States)

    Daryabeigi, Kamran; Cunnington, George R.; Miller, Steve D.; Knutson, Jeffry R.

    2010-01-01

    Combined radiation and conduction heat transfer through various high-temperature, high-porosity, unbonded (loose) fibrous insulations was modeled based on first principles. The diffusion approximation was used for modeling the radiation component of heat transfer in the optically thick insulations. The relevant parameters needed for the heat transfer model were derived from experimental data. Semi-empirical formulations were used to model the solid conduction contribution of heat transfer in fibrous insulations with the relevant parameters inferred from thermal conductivity measurements at cryogenic temperatures in a vacuum. The specific extinction coefficient for radiation heat transfer was obtained from high-temperature steady-state thermal measurements with large temperature gradients maintained across the sample thickness in a vacuum. Standard gas conduction modeling was used in the heat transfer formulation. This heat transfer modeling methodology was applied to silica, two types of alumina, and a zirconia-based fibrous insulation, and to a variation of opacified fibrous insulation (OFI). OFI is a class of insulations manufactured by embedding efficient ceramic opacifiers in various unbonded fibrous insulations to significantly attenuate the radiation component of heat transfer. The heat transfer modeling methodology was validated by comparison with more rigorous analytical solutions and with standard thermal conductivity measurements. The validated heat transfer model is applicable to various densities of these high-porosity insulations as long as the fiber properties are the same (index of refraction, size distribution, orientation, and length). Furthermore, the heat transfer data for these insulations can be obtained at any static pressure in any working gas environment without the need to perform tests in various gases at various pressures.

  17. SINGLE PHASE HIGH FREQUENCY AC CONVERTER FOR INDUCTION HEATING APPLICATION

    Directory of Open Access Journals (Sweden)

    M.A INAYATHULLAAH,

    2010-12-01

    Full Text Available The proposed topology reduces the total harmonic distortion (THD of a high frequency AC/AC Converter well below the acceptable limit. This paper deals with a novel single phase AC/DC/AC soft switching utility frequency AC to high frequency AC converter. In this paper a single phase full bridge inverter with Vienna rectifier as front end is used instead of conventional diode bridge rectifier to provide continuous sinusoidal input current with nearly unity power factor at the source side with extremely low distortion.. This power converter is more suitable and acceptable for cost effective high frequency (HF consumer induction heating applications.

  18. High pressure ratio cryocooler with integral expander and heat exchanger

    Science.gov (United States)

    Crunkleton, J. A.; Smith, J. L., Jr.; Iwasa, Y.

    A new 1 W, 4.2 K cryocooler is under development that is intended to miniaturize helium temperature refrigeration systems using a high-pressure-ratio Collins-type cycle. The configuration resulted from optimization studies of a saturated vapor compression (SCV) cycle that employs miniature parallel-plate heat exchangers. The basic configuration is a long displacer in a close-fitting, thin-walled cylinder. The displacer-to-cylinder gap is the high-pressure passage of the heat exchanger, and the low-pressure passage is formed by a thin tube over the OD of the cylinder. A solenoid-operated inlet valve admits 40 atm helium to the displacer-to-cylinder gap at room temperature, while the solenoid-operated exhaust valve operates at 4 atm. The single-stage cryocooler produces 1 W of refrigeration at 40 K without precooling and at 20 K with liquid nitrogen precooling.

  19. Theoretical Prediction and Experimental Determination of Heating Time During High-Temperature Heat Treatment of Wood

    Directory of Open Access Journals (Sweden)

    LIU Xin-you

    2011-06-01

    Full Text Available Theoretical prediction provides basic understanding and guidance to correctly implement a certaintechnology in the production process. The present study uses a differential equation to predict the heattransfer time between the surface and core layer of wood during the heat treatment, with applicability inestimating the duration of heat treatments at high temperatures. The obtained prediction was compared withthe result of an experimental study performed on Chinese poplar wood with various thicknesses (20, 40 and60mm. During this experiment, the time necessary for the core of wood to reach a temperature of 100°C,130°C and finally 180°C was monitored and the recorded values were compared with the predicted ones.The result of this comparison proved that the experimental values matched the theoretically predicted times,validating thus the applicability of the proposed equation as prediction tool.

  20. High Recharge Areas in the Choushui River Alluvial Fan (Taiwan Assessed from Recharge Potential Analysis and Average Storage Variation Indexes

    Directory of Open Access Journals (Sweden)

    Jui-Pin Tsai

    2015-03-01

    Full Text Available High recharge areas significantly influence the groundwater quality and quantity in regional groundwater systems. Many studies have applied recharge potential analysis (RPA to estimate groundwater recharge potential (GRP and have delineated high recharge areas based on the estimated GRP. However, most of these studies define the RPA parameters with supposition, and this represents a major source of uncertainty for applying RPA. To objectively define the RPA parameter values without supposition, this study proposes a systematic method based on the theory of parameter identification. A surrogate variable, namely the average storage variation (ASV index, is developed to calibrate the RPA parameters, because of the lack of direct GRP observations. The study results show that the correlations between the ASV indexes and computed GRP values improved from 0.67 before calibration to 0.85 after calibration, thus indicating that the calibrated RPA parameters represent the recharge characteristics of the study area well; these data also highlight how defining the RPA parameters with ASV indexes can help to improve the accuracy. The calibrated RPA parameters were used to estimate the GRP distribution of the study area, and the GRP values were graded into five levels. High and excellent level areas are defined as high recharge areas, which composed 7.92% of the study area. Overall, this study demonstrates that the developed approach can objectively define the RPA parameters and high recharge areas of the Choushui River alluvial fan, and the results should serve as valuable references for the Taiwanese government in their efforts to conserve the groundwater quality and quantity of the study area.

  1. High power laser heating of low absorption materials

    Energy Technology Data Exchange (ETDEWEB)

    Olson, K.; Talghader, J., E-mail: joey@umn.edu [Electrical Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Ogloza, A. [Naval Postgraduate School, 1 University Cir, Monterey, California 93943 (United States); Thomas, J. [Electro Optics Center, Pennsylvania State University, 222 Northpointe Blvd., Freeport, Pennsylvania 16229 (United States)

    2014-09-28

    A model is presented and confirmed experimentally that explains the anomalous behavior observed in continuous wave (CW) excitation of thermally isolated optics. Distributed Bragg Reflector (DBR) high reflective optical thin film coatings of HfO₂ and SiO₂were prepared with a very low absorption, about 7 ppm, measured by photothermal common-path interferometry. When illuminated with a 17 kW CW laser for 30 s, the coatings survived peak irradiances of 13 MW/cm², on 500 μm diameter spot cross sections. The temperature profile of the optical surfaces was measured using a calibrated thermal imaging camera for illuminated spot sizes ranging from 500 μm to 5 mm; about the same peak temperatures were recorded regardless of spot size. This phenomenon is explained by solving the heat equation for an optic of finite dimensions and taking into account the non-idealities of the experiment. An analytical result is also derived showing the relationship between millisecond pulse to CW laser operation where (1) the heating is proportional to the laser irradiance (W/m²) for millisecond pulses, (2) the heating is proportional to the beam radius (W/m) for CW, and (3) the heating is proportional to W/m∙ tan⁻¹(√(t)/m) in the transition region between the two.

  2. Effect of High Pressure and Heat on Bacterial Toxins

    Directory of Open Access Journals (Sweden)

    Dirk Margosch

    2005-01-01

    Full Text Available Even though the inactivation of microorganisms by high pressure treatment is a subject of intense investigations, the effect of high pressure on bacterial toxins has not been studied so far. In this study, the influence of combined pressure/temperature treatment (0.1 to 800 MPa and 5 to 121 °C on bacterial enterotoxins was determined. Therefore, heat-stable enterotoxin (STa of cholera toxin (CT from Vibrio cholerae, staphylococcal enterotoxins A-E, haemolysin BL (HBL from Bacillus cereus, and Escherichia coli (STa were subjected to different treatment schemes. Structural alterations were monitored in enzyme immunoassays (EIAs. Cytotoxicity of the pressure treated supernatant of toxigenic B. cereus DSM 4384 was investigated with Vero cells. High pressure of 200 to 800 MPa at 5 °C leads to a slight increase of the reactivity of the STa of E. coli. However, reactivity decreased at 800 MPa and 80 °C to (66±21 % after 30 min and to (44±0.3 % after 128 min. At ambient pressure no decrease in EIA reactivity could be observed after 128 min. Pressurization (0.1 to 800 MPa of heat stable monomeric staphylococcal toxins at 5 and 20 °C showed no effect. A combined heat (80 °C and pressure (0.1 to 800 MPa treatment lead to a decrease in the immuno-reactivity to 20 % of its maximum. For cholera toxin a significant loss in latex agglutination was observable only at 80 °C and 800 MPa for holding times higher than 20 min. Interestingly, the immuno-reactivity of B. cereus HBL toxin increased with the increase of pressure (182 % at 800 MPa, 30 °C, and high pressure showed only minor effects on cytotoxicity to Vero cells. Our results indicate that pressurization can increase inactivation observed by heat treatment, and combined treatments may be effective at lower temperatures and/or shorter incubation time.

  3. Analysis of Unsteady Tip and Endwall Heat Transfer in a Highly Loaded Transonic Turbine Stage

    Science.gov (United States)

    Shyam, Vikram; Ameri, Ali; Chen, Jen-Ping

    2010-01-01

    In a previous study, vane-rotor shock interactions and heat transfer on the rotor blade of a highly loaded transonic turbine stage were simulated. The geometry consists of a high pressure turbine vane and downstream rotor blade. This study focuses on the physics of flow and heat transfer in the rotor tip, casing and hub regions. The simulation was performed using the Unsteady Reynolds-Averaged Navier-Stokes (URANS) code MSU-TURBO. A low Reynolds number k-epsilon model was utilized to model turbulence. The rotor blade in question has a tip gap height of 2.1 percent of the blade height. The Reynolds number of the flow is approximately 3x10(exp 6) per meter. Unsteadiness was observed at the tip surface that results in intermittent "hot spots". It is demonstrated that unsteadiness in the tip gap is governed by inviscid effects due to high speed flow and is not strongly dependent on pressure ratio across the tip gap contrary to published observations that have primarily dealt with subsonic tip flows. The high relative Mach numbers in the tip gap lead to a choking of the leakage flow that translates to a relative attenuation of losses at higher loading. The efficacy of new tip geometry is discussed to minimize heat flux at the tip while maintaining choked conditions. In addition, an explanation is provided that shows the mechanism behind the rise in stagnation temperature on the casing to values above the absolute total temperature at the inlet. It is concluded that even in steady mode, work transfer to the near tip fluid occurs due to relative shearing by the casing. This is believed to be the first such explanation of the work transfer phenomenon in the open literature. The difference in pattern between steady and time-averaged heat flux at the hub is also explained.

  4. High Heat-Load Slits for the PLS Multipole Wiggler

    CERN Document Server

    Gil, Kyehwan; Kim, Young-Chan; Lee, Heung-Soo; Wha Chung, Chin

    2005-01-01

    The HFMX (High Flux Macromolecular X-ray crystallography) beamline under commissioning at Pohang Accelerator Laboratory uses beam from a multipole wiggler for MAD experiment. Two horizontal and vertical slits relevant to high heat load are installed at its front-end. In order to treat high heat load and to reduce beam scattering, the horizontal slit has two glidcop blocks with 10° of vertical inclination and its tungsten blades defining beam size are bolted on backsides of both blocks. The blocks of the slit are adjusted on fixed slides by two actuating bars, respectively. Water through channels machined along the actuating bars cool down the heat load of both blocks. The vertical slit has the same structure as the horizontal slit except its installation direction and angle of vertical inclination. The installed slits show stable operation performance and no alignment for the blocks is required by virtue of a pair of blocks translating on slides. The cooling performance of two slits is also shown to ...

  5. High Power, Solid-State RF Generation for Plasma Heating

    Science.gov (United States)

    Prager, James; Ziemba, Timothy; Miller, Kenneth; Pierren, Chris

    2016-10-01

    Radio Frequency heating systems are rarely used by the small-scale validation platform experiments due to the high cost and complexity of these systems. Eagle Harbor Technologies (EHT), Inc. is developing an all-solid-state RF plasma heating system that uses EHT's nanosecond pulser technology in an inductive adder configuration to drive nonlinear transmission lines (NLTL). The system under development does not require the use of vacuum tube technology, is inherently lower cost, and is more robust than traditional high power RF heating schemes. The inductive adder can produce 0 to20 kV pulses into 50 Ohms with sub-10 ns rise times. The inductive adder has been used to drive NLTLs near 2 GHz with other frequencies to be tested in the future. EHT will present experimental results, including RF measurements with D-dot probes and capacitve voltage probes. During this program, EHT will test the system on Helicity Injected Torus at the University of Washington and the High Beta Tokamak at Columbia University.

  6. The Baryon Cycle at High Redshifts: Effects of Galactic Winds on Galaxy Evolution in Overdense and Average Regions

    Science.gov (United States)

    Sadoun, Raphael; Shlosman, Isaac; Choi, Jun-Hwan; Romano-Díaz, Emilio

    2016-10-01

    We employ high-resolution cosmological zoom-in simulations focusing on a high-sigma peak and an average cosmological field at z ˜ 6-12 in order to investigate the influence of environment and baryonic feedback on galaxy evolution in the reionization epoch. Strong feedback, e.g., galactic winds, caused by elevated star formation rates (SFRs) is expected to play an important role in this evolution. We compare different outflow prescriptions: (i) constant wind velocity (CW), (ii) variable wind scaling with galaxy properties (VW), and (iii) no outflows (NW). The overdensity leads to accelerated evolution of dark matter and baryonic structures, absent from the “normal” region, and to shallow galaxy stellar mass functions at the low-mass end. Although CW shows little dependence on the environment, the more physically motivated VW model does exhibit this effect. In addition, VW can reproduce the observed specific SFR (sSFR) and the sSFR-stellar mass relation, which CW and NW fail to satisfy simultaneously. Winds also differ substantially in affecting the state of the intergalactic medium (IGM). The difference lies in the volume-filling factor of hot, high-metallicity gas, which is near unity for CW, while such gas remains confined in massive filaments for VW, and locked up in galaxies for NW. Such gas is nearly absent from the normal region. Although all wind models suffer from deficiencies, the VW model seems to be promising in correlating the outflow properties with those of host galaxies. Further constraints on the state of the IGM at high z are needed to separate different wind models.

  7. Process optimization in high-average-power ultrashort pulse laser microfabrication: how laser process parameters influence efficiency, throughput and quality

    Science.gov (United States)

    Schille, Joerg; Schneider, Lutz; Loeschner, Udo

    2015-09-01

    In this paper, laser processing of technical grade stainless steel and copper using high-average-power ultrashort pulse lasers is studied in order to gain deeper insight into material removal for microfabrication. A high-pulse repetition frequency picosecond and femtosecond laser is used in conjunction with high-performance galvanometer scanners and an in-house developed two-axis polygon scanner system. By varying the processing parameters such as wavelength, pulse length, fluence and repetition rate, cavities of standardized geometry are fabricated and analyzed. From the depths of the cavities produced, the ablation rate and removal efficiency are estimated. In addition, the quality of the cavities is evaluated by means of scanning electron microscope micrographs or rather surface roughness measurements. From the results obtained, the influence of the machining parameters on material removal and machining quality is discussed. In addition, it is shown that both material removal rate and quality increase by using femtosecond compared to picosecond laser pulses. On stainless steel, a maximum throughput of 6.81 mm3/min is achieved with 32 W femtosecond laser powers; if using 187 W picosecond laser powers, the maximum is 15.04 mm3/min, respectively. On copper, the maximum throughputs are 6.1 mm3/min and 21.4 mm3/min, obtained with 32 W femtosecond and 187 W picosecond laser powers. The findings indicate that ultrashort pulses in the mid-fluence regime yield most efficient material removal. In conclusion, from the results of this analysis, a range of optimum processing parameters are derived feasible to enhance machining efficiency, throughput and quality in high-rate micromachining. The work carried out here clearly opens the way to significant industrial applications.

  8. The Baryon Cycle at High Redshifts: Effects of Galactic Winds on Galaxy Evolution in Overdense and Average Regions

    CERN Document Server

    Sadoun, Raphael; Choi, Jun-Hwan; Romano-Díaz, Emilio

    2015-01-01

    We use high-resolution cosmological zoom-in simulations in order to analyze galaxy evolution at redshifts z~6-12 in highly-overdense 5 sigma density peaks. Strong stellar feedback, in the form of galactic winds, is expected to play an important role in the evolution of these regions. We investigate the effects of these winds by comparing different galactic outflow prescriptions, including (i) a constant velocity model (CW), (ii) a variable velocity model scaling with galaxy properties (VW), and (iii) a model with no outflows (NW). The CW model is also applied to a simulation of an average density region to study the impact of environment on galaxy evolution. A direct consequence of the overdensity is a shallow galaxy mass function slope at the low-mass end and an accelerated evolution of dark matter and baryonic structures. The overdensity hosts massive haloes, up to ~10^{12} Msun, with embedded galaxies up to ~10^{11} Msun in stellar mass by z~6, which are absent in the "normal" region. The CW model leads to...

  9. Analysis of high-frequency energy in long-term average spectra of singing, speech, and voiceless fricatives.

    Science.gov (United States)

    Monson, Brian B; Lotto, Andrew J; Story, Brad H

    2012-09-01

    The human singing and speech spectrum includes energy above 5 kHz. To begin an in-depth exploration of this high-frequency energy (HFE), a database of anechoic high-fidelity recordings of singers and talkers was created and analyzed. Third-octave band analysis from the long-term average spectra showed that production level (soft vs normal vs loud), production mode (singing vs speech), and phoneme (for voiceless fricatives) all significantly affected HFE characteristics. Specifically, increased production level caused an increase in absolute HFE level, but a decrease in relative HFE level. Singing exhibited higher levels of HFE than speech in the soft and normal conditions, but not in the loud condition. Third-octave band levels distinguished phoneme class of voiceless fricatives. Female HFE levels were significantly greater than male levels only above 11 kHz. This information is pertinent to various areas of acoustics, including vocal tract modeling, voice synthesis, augmentative hearing technology (hearing aids and cochlear implants), and training/therapy for singing and speech.

  10. Performance study of highly efficient 520 W average power long pulse ceramic Nd:YAG rod laser

    Science.gov (United States)

    Choubey, Ambar; Vishwakarma, S. C.; Ali, Sabir; Jain, R. K.; Upadhyaya, B. N.; Oak, S. M.

    2013-10-01

    We report the performance study of a 2% atomic doped ceramic Nd:YAG rod for long pulse laser operation in the millisecond regime with pulse duration in the range of 0.5-20 ms. A maximum average output power of 520 W with 180 J maximum pulse energy has been achieved with a slope efficiency of 5.4% using a dual rod configuration, which is the highest for typical lamp pumped ceramic Nd:YAG lasers. The laser output characteristics of the ceramic Nd:YAG rod were revealed to be nearly equivalent or superior to those of high-quality single crystal Nd:YAG rod. The laser pump chamber and resonator were designed and optimized to achieve a high efficiency and good beam quality with a beam parameter product of 16 mm mrad (M2˜47). The laser output beam was efficiently coupled through a 400 μm core diameter optical fiber with 90% overall transmission efficiency. This ceramic Nd:YAG laser will be useful for various material processing applications in industry.

  11. High resolution heat atlases for demand and supply mapping

    Directory of Open Access Journals (Sweden)

    Bernd Möller

    2014-02-01

    Full Text Available Significant reductions of heat demand, low-carbon and renewable energy sources, and district heating are key elements in 100% renewable energy systems. Appraisal of district heating along with energy efficient buildings and individual heat supply requires a geographical representation of heat demand, energy efficiency and energy supply. The present paper describes a Heat Atlas built around a spatial database using geographical information systems (GIS. The present atlas allows for per-building calculations of potentials and costs of energy savings, connectivity to existing district heat, and current heat supply and demand. For the entire building mass a conclusive link is established between the built environment and its heat supply. The expansion of district heating; the interconnection of distributed district heating systems; or the question whether to invest in ultra-efficient buildings with individual supply, or in collective heating using renewable energy for heating the current building stock, can be based on improved data.

  12. High resolution heat atlases for demand and supply mapping

    DEFF Research Database (Denmark)

    Möller, Bernd; Nielsen, Steffen

    2014-01-01

    Significant reductions of heat demand, low-carbon and renewable energy sources, and district heating are key elements in 100% renewable energy systems. Appraisal of district heating along with energy efficient buildings and individual heat supply requires a geographical representation of heat dem...

  13. Effect of droplet heat content distribution on humping formation in high speed GMAW

    Institute of Scientific and Technical Information of China (English)

    Ji CHEN; Chuansong WU

    2011-01-01

    The momentum of strong backward flowing melt jet and the thermal action from transferred droplets are two dominating factors affecting the formation of humping bead in high speed gas metal arc welding (GMAW).Appropriate describing the influence of the distribution mode of droplet heat content in the weld pool is essential to understand the physical mechanism of humping bead formation.Based on the experimental results,four kinds of droplet heat content distribution modes are proposed and employed to calculate the transient evolution of the temperature field and weld pool during high speed GMAW process.Through making comparison of predicted and measured weld bead dimensions,a suitable and adaptive distribution mode of droplet heat content is found,i.e.,droplet heat content is distributed in bottom layer of gouging region at the front of weld pool,and is averagely distributed in the whole layer at the rear of weld pool.The proposed mode is also validated by experimental observation of the weld pool images and measured by geometric dimensions of the weld bead.

  14. Workshop on high heat load x-ray optics

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    A workshop on High Heat Load X-Ray Optics'' was held at Argonne National Laboratory on August 3--5, 1989. The object of this workshop was to discuss recent advances in the art of cooling x-ray optics subject to high heat loads from synchrotron beams. The cooling of the first optical element in the intense photon beams that will be produced in the next generation of synchrotron sources is recognized as one of the major challenges that must be faced before one will be able to use these very intense beams in future synchrotron experiments. Considerable advances have been made in this art during the last few years, but much work remains to be done before the heating problem can be said to be completely solved. Special emphasis was placed on recent cooling experiments and detailed finite element'' and finite difference'' calculations comparing experiment with theory and extending theory to optimize performance.

  15. High-efficiency Commercial Cold Climate Heat Pump

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoud, Ahmad M. [United Technologies Research Center, East Hartford, CT (United States); Cogswell, F. [United Technologies Research Center, East Hartford, CT (United States); Verma, P. [United Technologies Research Center, East Hartford, CT (United States)

    2015-08-28

    United Technologies Research Center (UTRC) proposed in 2012 to design, develop and demonstrate an air-source 10TR high-efficiency commercial cold climate heat pump (CCCHP). The proposed heat pump would be scalable beyond 40TR, cost effective with a simple payback of < 3 years upon commercialization and would reduce annual electricity use for building space heating in cold climates by at least 20%. This would represent an annual savings of $2.3 billion and a 20% displacement of total greenhouse gases generated upon full commercialization. The primary objective was to develop a highly integrated system that shall meet or exceed DOE capacity and efficiency targets at key conditions and is scalable, cost-effective and simple relative to the state-of-the-art. Specifically, the goal of the project was to design, develop and demonstrate a CCCHP that exceeds DOE capacity degradation requirements at +17F and -13F conditions (0 and <15% degradation vs. 10 and 25% DOE requirements, respectively) while meeting or exceeding DOE capacity and system efficiency requirements at all other conditions.

  16. Laser heating challenges of high yield MagLIF targets

    Science.gov (United States)

    Slutz, Stephen; Sefkow, Adam; Vesey, Roger

    2014-10-01

    The MagLIF (Magnetized Liner Inertial Fusion) concept is predicted by numerical simulation to produce fusion yields of about 100 kJ, when driven by 25 MA from the existing Z accelerator [S. A. Slutz et al. Phys. Plasmas 17, 056303 (2010)] and much higher yields with future accelerators delivering higher currents [Slutz and Vesey PRL 108, 025003 (2012)]. The fuel must be heated before compression to obtain significant fusion yields due to the relatively slow implosion velocities (~ 100 km/s) of magnetically driven liners. Lasers provide a convenient means to accomplish this pre-compressional heating of the fusion fuel, but there are challenges. The laser must penetrate a foil covering the laser entrance hole and deposit 20-30 kJ within the ~1 cm length of the liner in fuel at 6-12 mg/cc. Such high densities could result in beam scattering due to refraction and laser plasma interactions. Numerical simulations of the laser heating process are presented, which indicate that energies as high as 30 kJ could be deposited in the fuel by using two laser pulses of different wavelengths. Simulations of this process will be presented as well of results for a MagLIF design for a potential new machine delivering 50 MA of current. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  17. Development of High-Field ST Merging Experiment: TS-U for High Power Reconnection Heating

    Science.gov (United States)

    Ono, Y.; Koike, H.; Tanabe, H.; Himeno, S.; Ishida, S.; Kimura, K.; Kawanami, M.; Narita, M.; Takahata, Y.; Yokoyama, T.; Inomoto, M.; Cheng, C. Z.

    2016-10-01

    We are developing high-magnetic field ST merging/ reconnection experiment TS-U with Brec = 0.3-0.5T, based on our scaling law of reconnection heating energy proportional to square of the reconnecting (poloidal) magnetic field Brec. This scaling law indicates that the high-Brec ST merging will heat ions to the burning plasma regime without using any additional heating facility. Its mechanism is that the reconnection outflow accelerates mainly ions up to the poloidal Alfven speed like the Sweet-Parker model. The shock-like density pileups thermalize the accelerated ions in the down-streams in agreement with recent solar satellite observations and PIC simulation results. We already documented significant ion heating of spheromak and ST mergings up to 0.25keV in TS-3 and 1.2keV in MAST, leading us to the high-Brec merging experiment TS-U. It is noted that high-resolution (>500 channel) 2D measurements of ion and electron temperatures is being developed for the purpose of solving all acceleration and heating effects of magnetic reconnection, such as the huge outflow heating of ions in the downstream and electron heating localized at the X-point.

  18. High-quality Critical Heat Flux in Horizontally Coiled Tubes

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    An investigation on the high-quality dryout in two electrically heated coiled tubes with horizontally helix axes is reported.The temperature profiles both along the tube and around the circumference are measured.and it is found that the temperature profiles around the circumference are not identical for the corss-sections at different parts of the coil.The “local condition hypothesis” seems applicable under present conditions,and the critical heat flux qcr decreases with increasing critical quality xcr.The CHF increases as mass velocity and ratio of tube diameter to coil diameter(d/D) increases,and it seems not to be affected hby the system pressure.The CHF is larger with coils than that with straight tubes,and the difference increases with increasing mass velocity and d/D.

  19. Effects of very high turbulence on convective heat transfer

    Science.gov (United States)

    Moffat, R. J.; Maciejewski, P. K.

    1984-01-01

    The effects of high-intensity, large-scale turbulence on turbulent boundary-layer heat transfer are studied. Flow fields were produced with turbulence intensities up to 40% and length scales up to several times the boundary layer thickness. In addition, three different types of turbulence will be compared to see whether they have the same effect on the boundary layer. The three are: the far field of a free jet, flow downstream of a grid, and flow downstream of a simulated gas turbine combustor. Each turbulence field will be characterized by several measures: intensity (by component), scale, and spectrum. Heat transfer will be measured on a 2.5 m long, 0.5 m wide flat plate using the energy-balance technique. The same plate will be used in each of the four flow fields; a low-turbulence tunnel for baseline data, and the three flow situations mentioned.

  20. Maxwell-Cattaneo Heat Convection and Thermal Stresses Responses of a Semi-Infinite Medium to High-Speed Laser Heating due to High Speed Laser Heating

    Directory of Open Access Journals (Sweden)

    Abdallah I. A.

    2009-07-01

    Full Text Available Based on Maxwell-Cattaneo convection equation, the thermoelasticity problem is in- vestigated in this paper. The analytic solution of a boundary value problem for a semi- infinite medium with traction free surface heated by a high-speed laser-pulses have Dirac temporal profile is solved. The temperature, the displacement and the stresses distributions are obtained analytically using the Laplace transformation, and discussed at small time duration of the laser pulses. A numerical study for Cu as a target is performed. The results are presented graphically. The obtained results indicate that the small time duration of the laser pulses has no e ect on the finite velocity of the heat con- ductivity, but the behavior of the stress and the displacement distribution are affected due to the pulsed heating process and due to the structure of the governing equations.

  1. High resolution temperature measurement technique for measuring marine heat flow

    Institute of Scientific and Technical Information of China (English)

    QIN; YangYang; YANG; XiaoQiu; WU; BaoZhen; SUN; ZhaoHua; SHI; XiaoBin

    2013-01-01

    High resolution temperature measurement technique is one of the key techniques for measuring marine heat flow. Basing on Pt1000 platinum resistance which has the characteristics of high accuracy and good stability, we designed a bridge reversal excitation circuit for high resolution temperature measurement. And the deep ocean floor in-situ test results show that: (1) temperature deviation and peak-to-peak resolution of the first version circuit board (V1) are 1.960-1.990 mK and 0.980-0.995 m Kat 1.2-2.7°C, respectively; and temperature deviation and peak-to-peak resolution of the second circuit board (V2) are 2.260mK and 1.130 mK at 1.2-1.3°C, respectively; (2) During the 2012NSFC-IndOcean cruise, seafloor geothermal gradient at Ind2012HF03,-07 and-12 stations (water depth ranges from 3841 to 4541 m) were successfully measured, the values are 59.1,75.1 and 71.6°C/km, respectively. And the measurement errors of geothermal gradient at these three stations are less than 3.0% in terms of the peak-to-peak resolution. These indicate that the high resolution temperature measurement technique based on Pt1000 platinum resistance in this paper can be applied to marine heat flow measurement to obtain high precision geothermal parameters.

  2. Average exceptional Lie and Coxeter group hierarchies with special reference to the standard model of high energy particle physics

    Energy Technology Data Exchange (ETDEWEB)

    El Naschie, M.S. [King Abdullah Al Saud Institute of Nano and Advanced Technologies, Riyadh (Saudi Arabia)], E-mail: Chaossf@aol.com

    2008-08-15

    The notions of the order of a symmetry group may be extended to that of an average, non-integer order. Building on this extension, it can be shown that the five classical exceptional Lie symmetry groups could be extended to a hierarchy, the total sum of which is four times {alpha}-bar{sub 0}=137+k{sub 0} of the electromagnetic field. Subsequently it can be shown that all known and conjectured physical fields may be derived by E-infinity transfinite scaling transformation. Consequently E{sub 8}E{sub 8} exceptional Lie symmetry groups manifold, the SL(2,7){sub c} holographic modular curve boundary {gamma}(7), Einstein-Kaluza gravity R{sup (n=4)} and R{sup (n=5)} as well as the electromagnetic field are all topological transformations of each other. It is largely a matter of mathematical taste to choose E{sub 8} or the electromagnetic field associated with {alpha}-bar{sub 0} as derived or as fundamental. However since E{sub 8} has been extensively studied by the founding father of group theory and has recently been mapped completely, it seems beneficial to discuss at least high energy physics starting from the largest of the exceptional groups.

  3. Production Planning with Respect to Uncertainties. Simulator Based Production Planning of Average Sized Combined Heat and Power Production Plants; Produktionsplanering under osaekerhet. Simulatorbaserad produktionsplanering av medelstora kraftvaermeanlaeggningar

    Energy Technology Data Exchange (ETDEWEB)

    Haeggstaahl, Daniel [Maelardalen Univ., Vaesteraas (Sweden); Dotzauer, Erik [AB Fortum, Stockholm (Sweden)

    2004-12-01

    Production planning in Combined Heat and Power (CHP) systems is considered. The focus is on development and use of mathematical models and methods. Different aspects on production planning are discussed, including weather and load predictions. Questions relevant on the different planning horizons are illuminated. The main purpose with short-term (one week) planning is to decide when to start and stop the production units, and to decide how to use the heat storage. The main conclusion from the outline of pros and cons of commercial planning software are that several are using Mixed Integer Programming (MIP). In that sense they are similar. Building a production planning model means that the planning problem is formulated as a mathematical optimization problem. The accuracy of the input data determines the practical detail level of the model. Two alternatives to the methods used in today's commercial programs are proposed: stochastic optimization and simulator-based optimization. The basic concepts of mathematical optimization are outlined. A simulator-based model for short-term planning is developed. The purpose is to minimize the production costs, depending on the heat demand in the district heating system, prices of electricity and fuels, emission taxes and fees, etc. The problem is simplified by not including any time-linking conditions. The process model is developed in IPSEpro, a heat and mass-balance software from SimTech Simulation Technology. TOMLAB, an optimization toolbox in MATLAB, is used as optimizer. Three different solvers are applied: glcFast, glcCluster and SNOPT. The link between TOMLAB and IPSEpro is accomplished using the Microsoft COM technology. MATLAB is the automation client and contains the control of IPSEpro and TOMLAB. The simulator-based model is applied to the CHP plant in Eskilstuna. Two days are chosen and analyzed. The optimized production is compared to the measured. A sensitivity analysis on how variations in outdoor

  4. High Magnetic Field Processing - A Heat-Free Heat Treating Method

    Energy Technology Data Exchange (ETDEWEB)

    Ludtka, Gerard Michael [ORNL; Ludtka, Gail Mackiewicz- [ORNL; Wilgen, John B [ORNL; Kenik, Edward A [ORNL; Parish, Chad M [ORNL; Rios, Orlando [ORNL; Rogers, Hiram [ORNL; Manuel, Michele [University of Florida, Gainesville; Kisner, Roger A [ORNL; Watkins, Thomas R [ORNL; Murphy, Bart L [ORNL

    2012-08-01

    The High and Thermal Magnetic Processing/Electro-magnetic Acoustic Transducer (HTMP/EMAT) technology has been shown to be an enabling disruptive materials processing technology, that can achieve significant improvements in microstructure and consequently material performance beyond that achievable through conventional processing, and will lead to the next generation of advanced performance structural and functional materials. HTMP exposure increased the reaction kinetics enabling refinement of microstructural features such as finer martensite lath size, and finer, more copious, homogeneous dispersions of strengthening carbides leading to combined strength and toughness improvements in bainitic steels. When induction heating is applied in a high magnetic field environment, the induction heating coil is configured so that high intensity acoustic/ultrasonic treatment occurs naturally. The configuration results in a highly effective electromagnetic acoustical transducer (EMAT). HTMP combined with applying high-field EMAT, produce a non-contact ultrasonic treatment that can be used to process metal alloys in either the liquid state resulting in significant microstructural changes over conventional processing. Proof-of-principle experiments on cast irons resulted in homogeneous microstructures in small castings along with improved casting surface appearance. The experiment showed that by exposing liquid metal to the non-contact acoustic/ultrasonic processing technology developed using HMFP/EMAT wrought-like microstructures were developed in cast components. This Energy Intensive Processes (EIP) project sponsored by the DOE EERE Advanced Manufacturing Office (AMO) demonstrated the following: (1) The reduction of retained austenite in high carbon/high alloy steels with an ambient temperature HTMP process, replacing either a cryogenic or double tempering thermal process normally employed to accomplish retained austenite transformation. HTMP can be described as a 'heat

  5. Predicting high harmonic ion cyclotron heating efficiency in Tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Green, David L [ORNL; Jaeger, E. F. [XCEL; Berry, Lee A [ORNL; Chen, Guangye [ORNL; Ryan, Philip Michael [ORNL; Canik, John [ORNL

    2011-01-01

    Observations of improved radio frequency (RF) heating efficiency in high-confinement (H-) mode plasmas on the National Spherical Tokamak Experiment (NSTX) are investigated by whole-device linear simulation. We present the first full-wave simulation to couple kinetic physics of the well confined core plasma to the poorly confined scrape-off plasma. The new simulation is used to scan the launched fast-wave spectrum and examine the steady-state electric wave field structure for experimental scenarios corresponding to both reduced, and improved RF heating efficiency. We find that launching toroidal wave-numbers that required for fast-wave propagation excites large amplitude (kVm 1 ) coaxial standing modes in the wave electric field between the confined plasma density pedestal and conducting vessel wall. Qualitative comparison with measurements of the stored plasma energy suggest these modes are a probable cause of degraded heating efficiency. Also, the H-mode density pedestal and fast-wave cutoff within the confined plasma allow for the excitation of whispering gallery type eigenmodes localised to the plasma edge.

  6. Pyrolysis kinetics of bagasse at high heating rates

    Energy Technology Data Exchange (ETDEWEB)

    Stubington, J.F.; Aiman, S. (University of New South Wales, Kensington, NSW (Australia). Dept. of Fuel Technology)

    The rate of pyrolysis of bagasse was studied at high heating rates (200-10,000 [degree]C/s) to obtain engineering data for incorporation into computational fluid dynamic models of bagasse ignition and combustion in suspension-fired and swirl burners. Experiments were performed using an electrically-heated grid under a nitrogen atmosphere at atmosphere pressure. Yields of char, tar, individual gas components, and water were measured as a function of peak temperature, for ranges of heating rate, residence time at peak temperature, and particle size. At higher peak temperatures, significant tar cracking occurred so that tar yields passed through a maximum as peak temperature increased. For dry bagasse, this tar cracking produced gases with no change in char yield, suggesting that it occurred external to the particle. Moisture in the atmosphere increased the tar cracking in the vapor phase outside the bagasse particle producing more gases but did not affect the char yield. However, moisture in the bagasse reduced the char yield and further enhanced the tar cracking reactions, producing even more gases (predominantly carbon monoxide). These results suggested an interaction between water vapor and the tar cracking reactions. For the short residence times appropriate to such burners, a single, first-order reaction model gave the best fit to the total weight loss for the ranges of heating rate and particle sizes studied. However, the first-order kinetic parameters fitted to primary tar production were recommended for modeling purposes because the total weight loss included significant yields of noncombustible water and carbon dioxide. Different ultimate primary tar yields were recommended to fit the dry and wet bagasse pyrolysis results. No chemical significance should be attributed to the kinetic parameters, which were determined to provide the simplest and best fit to the pyrolysis data. 19 refs., 15 figs., 5 tabs.

  7. Design and Calibration of a Novel High Temperature Heat Flux Sensor

    OpenAIRE

    Raphael-Mabel, Sujay Anand

    2005-01-01

    Heat flux gages are important in applications where measurement of the transfer of energy is more important than measurement of the temperature itself. There is a need for a heat flux sensor that can perform reliably for long periods of time in high temperature and high heat flux environment. The primary objective is to design and build a heat flux sensor that is capable of operating for extended periods of time in a high heat flux and high temperature environment. A High Temperature Heat F...

  8. Method for calculating Average Temperature of Tubesheet in Heat Exchanger with Dual Tubesheets%双管板换热器管板平均金属温度的一种计算方法

    Institute of Scientific and Technical Information of China (English)

    袁博; 许学斌; 陈仓社

    2016-01-01

    Numerical simulation of heat transfer performance for the tubesheet and its adjacent fluid area in dual tubesheet heat exchanger was carried out in this article by using software Fluent. With heat transfer model established, the heat transfer mechanism was studied. The heat transfer equation was then provided and the method for calculating average metal temperature of tubesheet was proposed. It was shown that the simulation result was coincident with theoretical solution. Thus the correctness of heat transfer equation has been verified by simulation result.%利用FLUENT软件对双管板换热器管板及其邻近流体区域的传热特性进行了数值模拟研究,通过建立传热模型,对其传热机理进行了研究,给出了描述其传热过程的传热方程,提出了管板平均金属温度的计算方法。结果表明:管板平均金属温度的模拟结果与理论解相符,模拟结果验证了传热方程的正确性。

  9. Study of Volumetrically Heated Ultra-High Energy Density Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Rocca, Jorge J. [Colorado State Univ., Fort Collins, CO (United States)

    2016-10-27

    Heating dense matter to millions of degrees is important for applications, but requires complex and expensive methods. The major goal of the project was to demonstrate using a compact laser the creation of a new ultra-high energy density plasma regime characterized by simultaneous extremely high temperature and high density, and to study it combining experimental measurements and advanced simulations. We have demonstrated that trapping of intense femtosecond laser pulses deep within ordered nanowire arrays can heat near solid density matter into a new ultra hot plasma regime. Extreme electron densities, and temperatures of several tens of million degrees were achieved using laser pulses of only 0.5 J energy from a compact laser. Our x-ray spectra and simulations showed that extremely highly ionized plasma volumes several micrometers in depth are generated by irradiation of gold and Nickel nanowire arrays with femtosecond laser pulses of relativistic intensities. We obtained extraordinarily high degrees of ionization (e.g. we peeled 52 electrons from gold atoms, and up to 26 electrons from nickel atoms). In the process we generated Gigabar pressures only exceeded in the central hot spot of highly compressed thermonuclear fusion plasmas.. The plasma created after the dissolved wires expand, collide, and thermalize, is computed to have a thermal energy density of 0.3 GJ cm-3 and a pressure of 1-2 Gigabar. These are pressures only exceeded in highly compressed thermonuclear fusion plasmas. Scaling these results to higher laser intensities promises to create plasmas with temperatures and pressures exceeding those in the center of the sun.

  10. High temperature polymer fuel cells. Heat utilization and co tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Jens, Oluf Jensen; Qingfeng, Li; Ronghuan, He; Gang, Xiao; Ji-An, Gao; Bjerrum, N.J. [Denmark Technical Univ., Department of Chemistry, Lyngby (Denmark)

    2003-09-01

    This paper will report recent results from our group on polymer fuel cells (PEMFC) based on the temperature resistant polymer poly-benzimidazole (PBI), which allow working temperatures up to 200 C. The membrane has a water drag number near zero and need no water management at all. The high working temperature allows for utilization of the excess heat for fuel processing. Moreover, it provides an excellent CO tolerance of several percent, and the system needs no purification of hydrogen from a reformer. Continuous service for over 6 months at 150 C has been demonstrated. (authors)

  11. Performances of the High Strength Low Heat Pump Concrete (HLPC)

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The effects of mineral admixtures on fluidity,mechanical and hydrational exothermic behavior were studied.The results show that,double-adding ways,i e,fly ash and slag were added at the same time,not only improves the fluidity of fresh concrete with low W/B and compensates the lower early compressive strength of harden concrete caused by high adding amount of fly ash, but also greatly reduces the highest temperature rise, exothermic rate and total heat liberation of 3 day of binder pastes in HLPC, and postponed the arrival time of the highest temperature rise. HLPC was prepared and applied to project practice successfully.

  12. ECE diagnostic of high temperature ECRH heated plasmas on FTU

    Energy Technology Data Exchange (ETDEWEB)

    Zerbini, M; Buratti, P; Tudisco, O; Giruzzi, G; Bruschi, A; Cirant, S; Granucci, G; Simonetto, A; Sozzi, C; Gandini, F; Pacella, D; Fournier, K B; Finkenthal, M

    2000-01-31

    The Electron Cyclotron Emission (ECE) diagnostic on FTU tokamak is routinely performed with a Michelson interferometer with spectral range extending up to 1300 GHz. The diagnostic allowed accurate electron temperature measurements during the recent 140 Ghz Electron Cyclotron Resonance Heating (ECRH) experiments on FTU. Very accurate measurements have been performed on a wide range of electron temperatures and profile peaking. The ECE measurements have been compared with Thomson Scattering and with observations of X-ray spectra from highly stripped molybdenum ions. The suprathermal emission in these conditions has been studied.

  13. DEVELOPMENT OF A HIGH PERFORMANCE COLD CLIMATE HEAT PUMP

    Energy Technology Data Exchange (ETDEWEB)

    Horton, W. Travis [Purdue University; Groll, Eckhard A. [Purdue University; Braun, James E. [Purdue University

    2014-06-01

    The primary goals of the proposed project were to develop, test, and evaluate a high performance and cost-effective vapor compression air-source heat pump for use in cold climate regions. Vapor compression heat pumps are a proven technology, and have been used for many years to meet heating requirements for buildings in residential, commercial, and industrial applications. However, in climate regions that experience very low outdoor ambient temperatures both the heating capacity and coefficient of performance (COP) of traditional air-source vapor compression heat pumps drops dramatically with a decrease in the outdoor air temperature. The efficiency of heat pumping equipment has improved substantially over the past 20 years; however, the efficiencies of the highest rated equipment on the market are approaching practical limits that cannot be surpassed without modifications to the basic cycle and possibly the use of additional hardware. In this report, three technologies to improve the efficiency of vapor compression systems are described. These are a) vapor injected compression, b) oil flooded compression and c) hybrid flow control of the evaporator. Compressor prototypes for both, oil flooded and vapor injected compression were developed by Emerson Climate Technologies. For the oil flooded compressor, the oil injection port location was optimized and an internal oil separator was added using several design iterations. After initial testing at Emerson Climate Technologies, further testing was done at Purdue University, and compressor models were developed. These models were then integrated into a system model to determine the achievable improvement of seasonal energy efficiency (SEER) for Minneapolis (Minnesota) climate. For the oil flooded compression, a 34% improvement in seasonal energy efficiency was found while a 21% improvement in seasonal energy efficiency ratio was found for the vapor injected compression. It was found that one benefit of both tested

  14. High heat flow and ocean acidification at a nascent rift in the northern Gulf of California

    Science.gov (United States)

    Prol-Ledesma, Rosa Ma; Torres-Vera, Marco-Antonio; Rodolfo-Metalpa, Riccardo; Ángeles, Catalina; Lechuga Deveze, Carlos H.; Villanueva-Estrada, Ruth Esther; Shumilin, Evgueni; Robinson, Carlos

    2013-01-01

    The prevailing tectonic setting in the Gulf California suggests the presence of an undetermined number of short spreading centres with associated hydrothermal systems. However, to date, active seafloor spreading phenomena have been documented in only three of the eight tectonically active basins. Here we report heat flow values as high as 15,436 mW m−2 in two of the northernmost basins of the Gulf of California, providing evidence of intense hydrothermal activity associated with the transition from continental rifting to seafloor spreading. The mean heat flow for the Wagner and Consag basins area is 1,875 mW m−2, more than 15 times higher than the mean value for oceanic crust (105.4 mW m−2). Additional evidence for vigorous hydrothermal circulation and a shallow heat source includes intense gas discharge (CO2 and CH4), widespread low pH (average 7.7), locally high 222Rn concentrations in the bottom water and a high extent of organic matter maturation in the sediments. PMID:23340428

  15. Reproducibility of High-Q SRF Cavities by High Temperature Heat Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Dhakal, Pashupati [JLAB; Ciovati, Gianluigi [JLAB; Kneisel, Peter [JLAB; Myneni, Ganapati Rao [JLAB

    2014-07-01

    Recent work on high-temperature (> 600 °C) heat treatment of ingot Nb cavities in a customized vacuum furnace for several hours showed the possibility of achieving Q0-values of up to ~5×1010 at 2.0 K, 1.5 GHz and accelerating gradients of ~20 MV/m. This contribution presents results on further studies of the heat treatment process to produce cavities with high Q0 values for continuous-wave accelerator application. Single-cell cavities of different Nb purity have been processed through few cycles of heat-treatments and chemical etching. Measurements of Q0 as a function of temperature at low RF field and of Q0 as a function of the RF field at or below 2.0 K have been made after each treatment. Measurements by TOF-SIMS of the impurities depth profiles were made on samples heat treated with the cavities.

  16. Electric heating provides a high level of home comfort - economically

    Energy Technology Data Exchange (ETDEWEB)

    Haapakoski, M.

    1997-11-01

    Research and development at IVO in the area of electric heating boasts a tradition going back almost thirty years. Research aimed at further progress is continuing. IVO and power companies launched the `Electrically heated houses of the century` project four years ago. The first results show that electric heating continues to be very competitive with other heating systems. It is an economical way of heating the home and it also increases the comfort of those living there

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

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.

    2003-01-01

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

  18. Modeling conductive heat transfer during high-pressure thawing processes: determination of latent heat as a function of pressure.

    Science.gov (United States)

    Denys, S; Van Loey, A M; Hendrickx, M E

    2000-01-01

    A numerical heat transfer model for predicting product temperature profiles during high-pressure thawing processes was recently proposed by the authors. In the present work, the predictive capacity of the model was considerably improved by taking into account the pressure dependence of the latent heat of the product that was used (Tylose). The effect of pressure on the latent heat of Tylose was experimentally determined by a series of freezing experiments conducted at different pressure levels. By combining a numerical heat transfer model for freezing processes with a least sum of squares optimization procedure, the corresponding latent heat at each pressure level was estimated, and the obtained pressure relation was incorporated in the original high-pressure thawing model. Excellent agreement with the experimental temperature profiles for both high-pressure freezing and thawing was observed.

  19. Mathematical Simulation of Heat Impact of Heated Up to High Temperatures Particle on Human Skin: Simple One-Dimensional Statement

    Directory of Open Access Journals (Sweden)

    Solodkin Andrey S.

    2014-01-01

    Full Text Available It is developed physical and mathematical models of process of a heat transfer between skin and a heating source - single heated up to high temperatures particle. Temperature distribution in system “particle-skin” for heated wooden particle is obtained. The data obtained during work can be used for addition of already available materials on the given subjects and comparisons of influences on a skin of various factors, and also can be useful to development of new systems of protection against the influences damaging factors in the conditions of fire.

  20. Quasi-passive heat sink for high-power laser diodes

    Science.gov (United States)

    Vetrovec, John

    2009-02-01

    We report on a novel heat sink for high-power laser diodes offering unparalleled capacity in high-heat flux handling and temperature control. The heat sink uses a liquid coolant flowing at high speed in a miniature closed and sealed loop. Diode waste heat is received at high flux and transferred to environment, coolant fluid, heat pipe, or structure at a reduced flux. When pumping solid-state or alkali vapor lasers, diode wavelength can be electronically tuned to the absorption features of the laser gain medium. This paper presents the heat sink physics, engineering design, performance modeling, and configurations.

  1. Reflectance-Based Estimation of Soil Heat Fluxes in the Texas High Plains

    Science.gov (United States)

    Gowda, P. H.; Colaizzi, P. D.; O'Shaughnessy, S.; Ha, W.; Howell, T. A.

    2010-12-01

    Soil heat flux (G) is one of the terms required for estimating evapotranspiration rates using an energy balance. Numerous reflectance-based models are available in the literature for estimating G fluxes. However, these models have shown wide variation in their performance. Therefore, operational ET remote sensing programs may require locally developed/calibrated models for accurately estimating G. The objective of this study was to develop and evaluate reflectance-based empirical G models for the semi-arid Texas High Plains. Soil heat flux was measured at 0.15 hz interval and averaged every 15 minutes at five different locations within a 4.7 ha lysimeter field with Pullman clay loam soil during the 2010 summer growing season. The field was planted to soybean and managed under dryland conditions. In each location, G was measured at 8 cm depth with two Campbell Scientific HFT3 soil heat flux plates. Soil temperature was measured at 2 and 6 cm above the soil heat flux plates. Soil moisture was measured in the 2-8 cm layer using Acclima SDI-12 sensors. Hourly G fluxes at the surface were calculated by adding the measured G fluxes at 8 cm to the energy stored above the heat flux plates. A multispectral radiometer (MSR, CROPSCAN, Inc.) and hand-held thermometer (EVEREST Interscience Inc.) measured surface reflectance in red and near infrared bandwidths and surface temperature (ST), respectively, daily at 11:30 AM CST to be consistent with the Landsat 5 overpass time. Fraction crop cover (FC) was measured by digital photographs taken twice a week. A set of G models was developed for estimating hourly fluxes based on measured reflectance, net radiation, ST, NDVI, and FC,. Resulting models were compared for performance with existing models available in the literature. In this presentation, we will discuss our G models for the Texas High Plains and the statistical results.

  2. Intensification of heat transfer in high-power laser diode bars by means of porous metal heat-sink

    Science.gov (United States)

    Apollonov, V. V.; Derzhavin, S. I.; Kuzminov, V. V.; Mashkovskiy, D. A.; Timoshkin, V. N.; Philonenko, V.

    1999-01-01

    To intensify a heat transfer in high-power emitters based on laser diode bars we propose the use of a heat sink from a porous permeable material cooled by a fluid flow [1-3]. The main advantage of this class of materials is the possibility of removing significant heat flows with compact heat sink. An analysis of the characteristic values of the thermal loads and their relations with the material and liquid parameters drawn from an one-dimensional model of stationary one-sided heat exchange shows the possibility of heat flow removal of more than 1.5 kW/cm 2 at room temperature in a liquid. Methods for improving the effectiveness of the strategy are considered.

  3. Highly turbulent solutions of the Lagrangian-averaged Navier-Stokes alpha model and their large-eddy-simulation potential.

    Science.gov (United States)

    Pietarila Graham, Jonathan; Holm, Darryl D; Mininni, Pablo D; Pouquet, Annick

    2007-11-01

    We compute solutions of the Lagrangian-averaged Navier-Stokes alpha - (LANS alpha ) model for significantly higher Reynolds numbers (up to Re approximately 8300 ) than have previously been accomplished. This allows sufficient separation of scales to observe a Navier-Stokes inertial range followed by a second inertial range specific to the LANS alpha model. Both fully helical and nonhelical flows are examined, up to Reynolds numbers of approximately 1300. Analysis of the third-order structure function scaling supports the predicted l3 scaling; it corresponds to a k-1 scaling of the energy spectrum for scales smaller than alpha. The energy spectrum itself shows a different scaling, which goes as k1. This latter spectrum is consistent with the absence of stretching in the subfilter scales due to the Taylor frozen-in hypothesis employed as a closure in the derivation of the LANS alpha model. These two scalings are conjectured to coexist in different spatial portions of the flow. The l3 [E(k) approximately k-1] scaling is subdominant to k1 in the energy spectrum, but the l3 scaling is responsible for the direct energy cascade, as no cascade can result from motions with no internal degrees of freedom. We demonstrate verification of the prediction for the size of the LANS alpha attractor resulting from this scaling. From this, we give a methodology either for arriving at grid-independent solutions for the LANS alpha model, or for obtaining a formulation of the large eddy simulation optimal in the context of the alpha models. The fully converged grid-independent LANS alpha model may not be the best approximation to a direct numerical simulation of the Navier-Stokes equations, since the minimum error is a balance between truncation errors and the approximation error due to using the LANS alpha instead of the primitive equations. Furthermore, the small-scale behavior of the LANS alpha model contributes to a reduction of flux at constant energy, leading to a shallower energy

  4. Progress in the development of active heat sink for high-power laser diodes

    Science.gov (United States)

    Vetrovec, John; Feeler, Ryan; Bonham, Steve

    2010-02-01

    We report on the development of a novel active heat sink for high-power laser diodes offering unparalleled capacity in high-heat flux handling and temperature control. The heat sink receives diode waste heat at high flux and transfers it at reduced flux to environment, coolant fluid, heat pipe, or structure. Thermal conductance of the heat sink is electronically adjustable, allowing for precise control of diode temperature and the output light wavelength. When pumping solid-state lasers, diode wavelength can be precisely tuned to the absorption features of the laser gain medium. This paper presents the AHS concept, scaling laws, model predictions, and data from initial testing.

  5. Process Heat Exchanger Options for the Advanced High Temperature Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Piyush Sabharwall; Eung Soo Kim; Michael McKellar; Nolan Anderson

    2011-06-01

    The work reported herein is a significant intermediate step in reaching the final goal of commercial-scale deployment and usage of molten salt as the heat transport medium for process heat applications. The primary purpose of this study is to aid in the development and selection of the required heat exchanger for power production and process heat application, which would support large-scale deployment.

  6. Process Heat Exchanger Options for Fluoride Salt High Temperature Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Piyush Sabharwall; Eung Soo Kim; Michael McKellar; Nolan Anderson

    2011-04-01

    The work reported herein is a significant intermediate step in reaching the final goal of commercial-scale deployment and usage of molten salt as the heat transport medium for process heat applications. The primary purpose of this study is to aid in the development and selection of the required heat exchanger for power production and process heat application, which would support large-scale deployment.

  7. High Heat Flux Burnout in Subcooled Flow Boiling

    Institute of Scientific and Technical Information of China (English)

    G.P.Celata; M.Cumo; 等

    1995-01-01

    The paper reports the results of an experimental research carried out at the Heat transfer divison of the Energy Department,C.R.Casaccia,on the thermal hydraulic characterization of subcooled flow boiling CHF under typical conditions of thermonuclear fusion reactors.I.e.high liquid velocity and subcooling.The experiment was carried out exploring the following parameters:channel diameter(from 2.5to 8.0 mm),heated length(10 and 15cm) ,liquid velocity (from 2 to 40m/s),exit pressure(from atmospheric to 5.0 MPa),inlet temperature(from 30 to 80℃),channel orientation (vertical and horizontal),A maximum CHF value of 60.6MW/m2 has been obtained under the following conditions:Tin-30°,p=2.5MPa,u=40m/s,D=2.5mm(smooth channel) Turbulence promoters(helically coiled wires)have been employed to further enhance the CHF attainable with subcooled flow boiling.Helically coiled wires allow an increase of 50% of the maximum CHF obtained with smooth channels.

  8. RECUPERATOR FOR HIGH-TEMPERATURE HEATING OF BLOWING

    Directory of Open Access Journals (Sweden)

    S. L. Rovin

    2011-01-01

    Full Text Available Heat recovery is an effective method of shortening specific energy consumption. New constructions of recuperators for heating and cupola furnaces have been designed and successfully introduced. Two-stage recuperator with computer control providing blast heating up to 600 °C and reducing fuel consumption by 30% is of special interest.

  9. Rapid heating of matter using high power lasers

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Woosuk [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-05

    This report describes rapid heating technology with ion sources. LANL calculated the expected heating per atom and temperatures of the target materials, used alumium ion beams to heat gold and diamond, produced deuterium fusion plasmas and then measured the ion temperature at the time of the fusion reactions.

  10. Optimization analysis of high temperature heat pump coupling to desiccant wheel air conditioning system

    DEFF Research Database (Denmark)

    Sheng, Ying; Zhang, Yufeng; Fang, Lei

    2014-01-01

    The high temperature heat pump and desiccant wheel (HTHP&DW) system can make full use of heat released from the condenser of heat pump for DW regeneration without additional heat. In this study, DW operation in the HTHP&DW system was investigated experimentally, and the optimization analysis....... Compared to the isosteric heat, heat accumulation in the desiccant and matrix material and heat leakage from regeneration side to process side have greater influence on the adiabatic effectiveness. Higher regeneration temperature leads to lower adiabatic effectiveness that increases more cooling load...

  11. Heat transfer and flow in high-temperature alkali-metal heat pipes

    Science.gov (United States)

    Nosach, N. A.; Gontarev, Iu. K.; Prisniakov, V. F.; Iakovenko, A. G.; Kostornov, A. G.

    1982-06-01

    An experimental study of the dynamics of heat pipes with steel wool and metal fiber wicks, in particular of startup and transition from one operating mode to another, is presented. The dynamics effect of the initial heat flux in the evaporator when NaK is the working fluid is determined. The effect of interaction between the liquid and vapor phases on the heat and mass transfer from the vapor condensing on the pipe wall is analyzed.

  12. High Magnetic Field Processing - A Heat-Free Heat Treating Method

    Energy Technology Data Exchange (ETDEWEB)

    Ludtka, Gerard Michael [ORNL; Ludtka, Gail Mackiewicz- [ORNL; Wilgen, John B [ORNL; Kenik, Edward A [ORNL; Parish, Chad M [ORNL; Rios, Orlando [ORNL; Rogers, Hiram [ORNL; Manuel, Michele [University of Florida, Gainesville; Kisner, Roger A [ORNL; Watkins, Thomas R [ORNL; Murphy, Bart L [ORNL

    2012-08-01

    The High and Thermal Magnetic Processing/Electro-magnetic Acoustic Transducer (HTMP/EMAT) technology has been shown to be an enabling disruptive materials processing technology, that can achieve significant improvements in microstructure and consequently material performance beyond that achievable through conventional processing, and will lead to the next generation of advanced performance structural and functional materials. HTMP exposure increased the reaction kinetics enabling refinement of microstructural features such as finer martensite lath size, and finer, more copious, homogeneous dispersions of strengthening carbides leading to combined strength and toughness improvements in bainitic steels. When induction heating is applied in a high magnetic field environment, the induction heating coil is configured so that high intensity acoustic/ultrasonic treatment occurs naturally. The configuration results in a highly effective electromagnetic acoustical transducer (EMAT). HTMP combined with applying high-field EMAT, produce a non-contact ultrasonic treatment that can be used to process metal alloys in either the liquid state resulting in significant microstructural changes over conventional processing. Proof-of-principle experiments on cast irons resulted in homogeneous microstructures in small castings along with improved casting surface appearance. The experiment showed that by exposing liquid metal to the non-contact acoustic/ultrasonic processing technology developed using HMFP/EMAT wrought-like microstructures were developed in cast components. This Energy Intensive Processes (EIP) project sponsored by the DOE EERE Advanced Manufacturing Office (AMO) demonstrated the following: (1) The reduction of retained austenite in high carbon/high alloy steels with an ambient temperature HTMP process, replacing either a cryogenic or double tempering thermal process normally employed to accomplish retained austenite transformation. HTMP can be described as a 'heat

  13. Impingement heat sinks for air cooled high power electronic modules

    Energy Technology Data Exchange (ETDEWEB)

    Kang, S.S.; Holahan, M.F. [IBM Corp., Rochester, MN (United States)

    1995-12-31

    The subject of the present work is a parallel plate heat sink that is designed so that the air flow impinges at the fin tips and exhausts over the two open side faces. This type of design attempts to achieve an air flow direction that is substantially opposite to the heat flow direction within the fins so as to exploit the greater heat transfer effectiveness of counterflow heat exchange. A one dimensional model of the heat sink was developed with the assumption of air flow from the fin tips to the fin base. This simplified model was used to identify an initial heat sink geometry to cool a specific multichip module. Computational Fluid Dynamics models that account for the actual flow pattern within the heat sink were used to study a range of variations to the initial geometry and to identify the best geometry over the range examined. Experimental heat transfer and pressure drop data is reported for two heat sink prototypes. The test data is in good agreement with CFD predictions. Suitable correlations for the heat sink thermal resistance and pressure drop versus the air flow rate are developed. The developed heat sink demonstrated an area specific thermal resistance better than 8.7 C (W/cm{sup 2}).

  14. Plasma–Surface Interactions Under High Heat and Particle Fluxes

    Directory of Open Access Journals (Sweden)

    Gregory De Temmerman

    2013-01-01

    Full Text Available The plasma-surface interactions expected in the divertor of a future fusion reactor are characterized by extreme heat and particle fluxes interacting with the plasma-facing surfaces. Powerful linear plasma generators are used to reproduce the expected plasma conditions and allow plasma-surface interactions studies under those very harsh conditions. While the ion energies on the divertor surfaces of a fusion device are comparable to those used in various plasma-assited deposition and etching techniques, the ion (and energy fluxes are up to four orders of magnitude higher. This large upscale in particle flux maintains the surface under highly non-equilibrium conditions and bring new effects to light, some of which will be described in this paper.

  15. Performance of water source heat pump system using high-density polyethylene tube heat exchanger wound with square copper wire

    Directory of Open Access Journals (Sweden)

    Xin Wen Zhang

    2015-07-01

    Full Text Available Surface water source heat pump system is an energy-efficient heat pump system. Surface water heat exchanger is an important part of heat pump system that can affect the performance of the system. In order to enhance the performance of the system, the overall heat transfer coefficient (U value of the water exchanger using a 32A square copper coiled high-density polyethylene tube was researched. Comparative experiments were conducted between the performance of the coiled high-density polyethylene tube and the 32A smooth high-density polyethylene tube. At the same time, the coefficient of performance of the heat pump was investigated. According to the result, the U value of the coiled tube was 18% higher than that of the smooth tube in natural convection and 19% higher in forced convection. The coefficient of performance of the heat pump with the coiled tube is higher than that with the smooth tube. The economic evaluation of the coiled tube was also investigated.

  16. Area-averaged evapotranspiration over a heterogeneous land surface: aggregation of multi-point EC flux measurements with a high-resolution land-cover map and footprint analysis

    Science.gov (United States)

    Xu, Feinan; Wang, Weizhen; Wang, Jiemin; Xu, Ziwei; Qi, Yuan; Wu, Yueru

    2017-08-01

    The determination of area-averaged evapotranspiration (ET) at the satellite pixel scale/model grid scale over a heterogeneous land surface plays a significant role in developing and improving the parameterization schemes of the remote sensing based ET estimation models and general hydro-meteorological models. The Heihe Watershed Allied Telemetry Experimental Research (HiWATER) flux matrix provided a unique opportunity to build an aggregation scheme for area-averaged fluxes. On the basis of the HiWATER flux matrix dataset and high-resolution land-cover map, this study focused on estimating the area-averaged ET over a heterogeneous landscape with footprint analysis and multivariate regression. The procedure is as follows. Firstly, quality control and uncertainty estimation for the data of the flux matrix, including 17 eddy-covariance (EC) sites and four groups of large-aperture scintillometers (LASs), were carefully done. Secondly, the representativeness of each EC site was quantitatively evaluated; footprint analysis was also performed for each LAS path. Thirdly, based on the high-resolution land-cover map derived from aircraft remote sensing, a flux aggregation method was established combining footprint analysis and multiple-linear regression. Then, the area-averaged sensible heat fluxes obtained from the EC flux matrix were validated by the LAS measurements. Finally, the area-averaged ET of the kernel experimental area of HiWATER was estimated. Compared with the formerly used and rather simple approaches, such as the arithmetic average and area-weighted methods, the present scheme is not only with a much better database, but also has a solid grounding in physics and mathematics in the integration of area-averaged fluxes over a heterogeneous surface. Results from this study, both instantaneous and daily ET at the satellite pixel scale, can be used for the validation of relevant remote sensing models and land surface process models. Furthermore, this work will be

  17. High Temperature Metal Hydrides as Heat Storage Materials for Solar and Related Applications

    Directory of Open Access Journals (Sweden)

    Borislav Bogdanović

    2009-01-01

    Full Text Available For the continuous production of electricity with solar heat power plants the storage of heat at a temperature level around 400 °C is essential. High temperature metal hydrides offer high heat storage capacities around this temperature. Based on Mg-compounds, these hydrides are in principle low-cost materials with excellent cycling stability. Relevant properties of these hydrides and their possible applications as heat storage materials are described.

  18. High temperature metal hydrides as heat storage materials for solar and related applications.

    Science.gov (United States)

    Felderhoff, Michael; Bogdanović, Borislav

    2009-01-01

    For the continuous production of electricity with solar heat power plants the storage of heat at a temperature level around 400 degrees C is essential. High temperature metal hydrides offer high heat storage capacities around this temperature. Based on Mg-compounds, these hydrides are in principle low-cost materials with excellent cycling stability. Relevant properties of these hydrides and their possible applications as heat storage materials are described.

  19. Mitochondrial DNA Marker EST00083 Is Not Associated with High vs. Average IQ in a German Sample.

    Science.gov (United States)

    Moises, Hans W.; Yang, Liu; Kohnke, Michael; Vetter, Peter; Neppert, Jurgen; Petrill, Stephen A.; Plomin, Robert

    1998-01-01

    Tested the association of a mitochondrial DNA marker (EST00083) with high IQ in a sample of 47 German adults with high IQ scores and 77 adults with IQs estimated at lower than 110. Results do not support the hypothesis that high IQ is associated with this marker. (SLD)

  20. Commercial high efficiency dehumidification systems using heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    1993-09-01

    An improved heat pipe design using separately connected two-section one-way flow heat pipes with internal microgrooves instead of wicks is described. This design is now commercially available for use to increase the dehumidification capacity of air conditioning systems. The design also includes a method of introducing fresh air into buildings while recovering heat and controlling the humidity of the incoming air. Included are applications and case studies, load calculations and technical data, and installation, operation, and maintenance information.

  1. High temperature heat exchanger studies for applications to gas turbines

    Science.gov (United States)

    Min, June Kee; Jeong, Ji Hwan; Ha, Man Yeong; Kim, Kui Soon

    2009-12-01

    Growing demand for environmentally friendly aero gas-turbine engines with lower emissions and improved specific fuel consumption can be met by incorporating heat exchangers into gas turbines. Relevant researches in such areas as the design of a heat exchanger matrix, materials selection, manufacturing technology, and optimization by a variety of researchers have been reviewed in this paper. Based on results reported in previous studies, potential heat exchanger designs for an aero gas turbine recuperator, intercooler, and cooling-air cooler are suggested.

  2. Mathematical Simulation of Heat Transfer in Heterogenous Forest Fuel Layer Influenced by Heated Up to High Temperatures Steel Particle

    Directory of Open Access Journals (Sweden)

    Baranovskiy Nikolay V.

    2014-01-01

    Full Text Available Heterogeneity of forest fuel layer renders the important influence on forest fire occurrence processes. One of sources of the raised temperature on forested territories is metal particles heated up to high temperatures. Such particles can be formed as a result of welding of metals on forested territories. The present paper represents the heat transfer research in forest fuel at the influence of metal particle heated up to high temperatures. The heterogonous forest fuel layer with inclusions of small wooden branches and chips is considered. Such object research is urgent especially at fire forecasting on forest cutting. The technology of mathematical simulation is used. The two-dimensional problem of heat transfer in forest fuel layer structure with wood inclusions is solved.

  3. Industrial heat pumps for high temperature process applications

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær

    Industrial processes often consume large quantities of heat, while of-ten dissipating large quantities of waste heat to the ambient. The main energy source for industrial heat supply is fossil fuels, either oil or nat-ural gas. Thus, the heat consumption of industrial processes often entail large...... is determined. This is know as an exergoeconomic analysis. Further, a life cycle assessment is performed and combined with the exergy analysis to associate environmental impact to all streams of exergy and thereby determine the environmental impact of exergy destruction. This is known as an exergoenvironmental...

  4. Thermal metamaterial for convergent transfer of conductive heat with high efficiency

    Science.gov (United States)

    Shen, Xiangying; Jiang, Chaoran; Li, Ying; Huang, Jiping

    2016-11-01

    It is crucially important to focus conductive heat in an efficient way, which has received much attention in energy science (say, solar cells), but is still far from being satisfactory due to the diffusive (divergent) nature of the heat. By developing a theory with hybrid transformations (rotation and stretch-compression), here we provide theoretical and experimental evidences for a type of thermal metamaterial called thermal converger. The converger is capable of convergently conducting heat in contrast to the known divergent behavior of heat diffusion, thus yielding a large heating region with high temperatures close to the heat source (high efficiency). The thermal converger further allows us to design a thermal grating—a thermal counterpart of optical grating. This work has relevance to heat focus with high efficiency, and it offers guidance both for efficient heat transfer and for designing thermal-converger-like metamaterials in other fields, such as electrics/magnetics, electromagnetics/optics, acoustics, and particle diffusion.

  5. An Analysis of Java Programming Behaviors, Affect, Perceptions, and Syntax Errors among Low-Achieving, Average, and High-Achieving Novice Programmers

    Science.gov (United States)

    Rodrigo, Ma. Mercedes T.; Andallaza, Thor Collin S.; Castro, Francisco Enrique Vicente G.; Armenta, Marc Lester V.; Dy, Thomas T.; Jadud, Matthew C.

    2013-01-01

    In this article we quantitatively and qualitatively analyze a sample of novice programmer compilation log data, exploring whether (or how) low-achieving, average, and high-achieving students vary in their grasp of these introductory concepts. High-achieving students self-reported having the easiest time learning the introductory programming…

  6. An Analysis of Java Programming Behaviors, Affect, Perceptions, and Syntax Errors among Low-Achieving, Average, and High-Achieving Novice Programmers

    Science.gov (United States)

    Rodrigo, Ma. Mercedes T.; Andallaza, Thor Collin S.; Castro, Francisco Enrique Vicente G.; Armenta, Marc Lester V.; Dy, Thomas T.; Jadud, Matthew C.

    2013-01-01

    In this article we quantitatively and qualitatively analyze a sample of novice programmer compilation log data, exploring whether (or how) low-achieving, average, and high-achieving students vary in their grasp of these introductory concepts. High-achieving students self-reported having the easiest time learning the introductory programming…

  7. Growth of a dry spot under a vapor bubble at high heat flux and high pressure

    CERN Document Server

    Nikolayev, Vadim; Lagier, G -L; Hegseth, J

    2016-01-01

    We report a 2D modeling of the thermal diffusion-controlled growth of a vapor bubble attached to a heating surface during saturated boiling. The heat conduction problem is solved in a liquid that surrounds a bubble with a free boundary and in a semi-infinite solid heater by the boundary element method. At high system pressure the bubble is assumed to grow slowly, its shape being defined by the surface tension and the vapor recoil force, a force coming from the liquid evaporating into the bubble. It is shown that at some typical time the dry spot under the bubble begins to grow rapidly under the action of the vapor recoil. Such a bubble can eventually spread into a vapor film that can separate the liquid from the heater thus triggering the boiling crisis (critical heat flux).

  8. Development of a high-performance boiling heat exchanger by improved liquid supply to narrow channels.

    Science.gov (United States)

    Ohta, Haruhiko; Ohno, Toshiyuki; Hioki, Fumiaki; Shinmoto, Yasuhisa

    2004-11-01

    A two-phase flow loop is a promising method for application to thermal management systems for large-scale space platforms handling large amounts of energy. Boiling heat transfer reduces the size and weight of cold plates. The transportation of latent heat reduces the mass flow rate of working fluid and pump power. To develop compact heat exchangers for the removal of waste heat from electronic devices with high heat generation density, experiments on a method to increase the critical heat flux for a narrow heated channel between parallel heated and unheated plates were conducted. Fine grooves are machined on the heating surface in a transverse direction to the flow and liquid is supplied underneath flattened bubbles by the capillary pressure difference from auxiliary liquid channels separated by porous metal plates from the main heated channel. The critical heat flux values for the present heated channel structure are more than twice those for a flat surface at gap sizes 2 mm and 0.7 mm. The validity of the present structure with auxiliary liquid channels is confirmed by experiments in which the liquid supply to the grooves is interrupted. The increment in the critical heat flux compared to those for a flat surface takes a maximum value at a certain flow rate of liquid supply to the heated channel. The increment is expected to become larger when the length of the heated channel is increased and/or the gravity level is reduced.

  9. An Automated Laboratory Laser Heating Arrangement for Materials Synthesis at High Temperatures and High Pressures

    CERN Document Server

    Subramanian, N; Bindu, R; Kumar, N R Sanjay; Sekar, M; Shekar, N V Chandra; Sahu, P Ch

    2008-01-01

    This paper describes the automation of a laser heating arrangement for synthesizing and studying materials at high pressures (up to ~ 1 Mbar) and high temperatures (up to ~ 5000 K). In this arrangement, a diamond anvil high-pressure cell (DAC) containing a microscopic sample of typical diameter ~50-100 micrometer, is mounted on a precision X-Y nanomotor stage that forms part of an IR laser heating optical assembly. Automation of this stage has been accomplished using a LabVIEW virtual instrument program to manipulate the X and Y stages using nanopositioning systems. This has a major feature of enabling a rastered heating of the sample over a user-defined circular area, without any operator intervention in addition to a virtual joystick to position the sample with respect to the laser spot. This auto-rastering feature has the advantage of offering uniform exposure of a circular area of the sample to the incident heating laser beam apart from drastic reduction in scan time compared to a manual scan. The diamete...

  10. Differential heating: A versatile method for thermal conductivity measurements in high-energy-density matter

    Energy Technology Data Exchange (ETDEWEB)

    Ping, Y.; Fernandez-Panella, A.; Correa, A.; Shepherd, R.; Landen, O.; London, R. A.; Sterne, P. A.; Whitley, H. D.; Fratanduono, D.; Collins, G. W. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Sio, H. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Boehly, T. R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

    2015-09-15

    We propose a method for thermal conductivity measurements of high energy density matter based on differential heating. A temperature gradient is created either by surface heating of one material or at an interface between two materials by different energy deposition. The subsequent heat conduction across the temperature gradient is observed by various time-resolved probing techniques. Conceptual designs of such measurements using laser heating, proton heating, and x-ray heating are presented. The sensitivity of the measurements to thermal conductivity is confirmed by simulations.

  11. Hybrid Heat Pipes for High Heat Flux Spacecraft Thermal Control Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Grooved aluminum/ammonia Constant Conductance Heat Pipes (CCHPs) are the standard for thermal control in zero-gravity. Unfortunately, they are limited in terms of...

  12. Hybrid Heat Pipes for Lunar and Martian Surface and High Heat Flux Space Applications

    Science.gov (United States)

    Ababneh, Mohammed T.; Tarau, Calin; Anderson, William G.; Farmer, Jeffery T.; Alvarez-Hernandez, Angel R.

    2016-01-01

    Novel hybrid wick heat pipes are developed to operate against gravity on planetary surfaces, operate in space carrying power over long distances and act as thermosyphons on the planetary surface for Lunar and Martian landers and rovers. These hybrid heat pipes will be capable of operating at the higher heat flux requirements expected in NASA's future spacecraft and on the next generation of polar rovers and equatorial landers. In addition, the sintered evaporator wicks mitigate the start-up problems in vertical gravity aided heat pipes because of large number of nucleation sites in wicks which will allow easy boiling initiation. ACT, NASA Marshall Space Flight Center, and NASA Johnson Space Center, are working together on the Advanced Passive Thermal experiment (APTx) to test and validate the operation of a hybrid wick VCHP with warm reservoir and HiK"TM" plates in microgravity environment on the ISS.

  13. Low, medium and high heat tolerant strains of Listeria monocytogenes and increased heat stress resistance after exposure to sublethal heat

    Science.gov (United States)

    Listeria monocytogenes exhibits sophisticated adaptive mechanisms to counteract higher levels of lethal acid, heat, salt or oxidative stresses after pre-exposure to sublethal concentrations of homogenous stress. A group of 37 strains representing all 13 serotypes of Listeria monocytogenes with initi...

  14. HIGH HEATING RATES AFFECTS GREATLY THE INACTIVATION RATE OF ESCHERICHIA COLI

    Directory of Open Access Journals (Sweden)

    Juan Pablo Huertas

    2016-08-01

    Full Text Available Heat resistance of microorganisms can be affected by different influencing factors. Although the effect of heating rates has been scarcely explored by the scientific community, recent researches have unraveled its important effect on the thermal resistance of different species of vegetative bacteria. Typically heating rates described in the literature ranged from 1 to 20ºC/min but the impact of much higher heating rates is unclear. The aim of this research was to explore the effect of different heating rates, such as those currently achieved in the heat exchangers used in the food industry, on the heat resistance of Escherichia coli. A pilot plant tubular heat exchanger and a thermoresistometer Mastia were used for this purpose. Results showed that fast heating rates had a deep impact on the thermal resistance of E. coli. Heating rates between 20 and 50ºC/min were achieved in the heat exchanger, which were much slower than those around 20ºC/s achieved in the thermoresistometer. In all cases, these high heating rates led to higher inactivation than expected: in the heat exchanger, for all the experiments performed, when the observed inactivation had reached about seven log cycles, the predictions estimates about 1 log cycle of inactivation; in the thermoresistometer these differences between observed and predicted values were even more than ten times higher, from 4.07 log cycles observed to 0.34 predicted at a flow rate of 70 mL/min and a maximum heating rate of 14.7ºC/s. A quantification of the impact of the heating rates on the level of inactivation achieved was established. These results point out the important effect that the heating rate has on the thermal resistance of E. coli, with high heating rates resulting in an additional sensitization to heat and therefore an effective food safety strategy in terms of food processing.

  15. High Heating Rates Affect Greatly the Inactivation Rate of Escherichia coli

    Science.gov (United States)

    Huertas, Juan-Pablo; Aznar, Arantxa; Esnoz, Arturo; Fernández, Pablo S.; Iguaz, Asunción; Periago, Paula M.; Palop, Alfredo

    2016-01-01

    Heat resistance of microorganisms can be affected by different influencing factors. Although, the effect of heating rates has been scarcely explored by the scientific community, recent researches have unraveled its important effect on the thermal resistance of different species of vegetative bacteria. Typically heating rates described in the literature ranged from 1 to 20°C/min but the impact of much higher heating rates is unclear. The aim of this research was to explore the effect of different heating rates, such as those currently achieved in the heat exchangers used in the food industry, on the heat resistance of Escherichia coli. A pilot plant tubular heat exchanger and a thermoresistometer Mastia were used for this purpose. Results showed that fast heating rates had a deep impact on the thermal resistance of E. coli. Heating rates between 20 and 50°C/min were achieved in the heat exchanger, which were much slower than those around 20°C/s achieved in the thermoresistometer. In all cases, these high heating rates led to higher inactivation than expected: in the heat exchanger, for all the experiments performed, when the observed inactivation had reached about seven log cycles, the predictions estimated about 1 log cycle of inactivation; in the thermoresistometer these differences between observed and predicted values were even more than 10 times higher, from 4.07 log cycles observed to 0.34 predicted at a flow rate of 70 mL/min and a maximum heating rate of 14.7°C/s. A quantification of the impact of the heating rates on the level of inactivation achieved was established. These results point out the important effect that the heating rate has on the thermal resistance of E. coli, with high heating rates resulting in an additional sensitization to heat and therefore an effective food safety strategy in terms of food processing. PMID:27563300

  16. Assessing the feasibility of high-density subsurface heat extraction in urban areas

    Science.gov (United States)

    Abesser, Corinna; Busby, Jonathan

    2017-04-01

    The subsurface is increasingly utilized as a heat source (sink) for use in heating (and cooling) applications. This is driven by the need to increase the amount of heat generated from renewable sources to meet the EU renewable energy target of 12% by 2020. This study explores the feasibility, performance and long-term sustainability of high density, closed-loop GSHP installations in urban areas. Specifically, it employs a 2D, finite element, heat transport model to assess the impact of high density heat extraction in a residential area in Reading. A block of semi-detached houses is modelled, assuming that separate GSHP systems are installed in every property. The model considers conductive and advective heat transport. Uncertainties are explored through varying thermal properties and groundwater gradients across the site. Different heat demand scenarios are evaluated and the impact on the subsurface temperature distribution and on heat pump efficiency is assessed. The scenarios are selected to represent variations in inter-annual weather pattern, heating pattern and building insulation standards. Results indicate that high density heat extraction for domestic heating can be sustainable over the lifespan expected for GSHP systems (of around 20 years), in particular where heat demand is reduced by home improvement measures. Based on the results, recommendations are being presented for the sustainable deployment of high density GSHP installation in urban areas.

  17. Implementation of a reference-scaled average bioequivalence approach for highly variable generic drug products of agomelatine in Chinese subjects

    Directory of Open Access Journals (Sweden)

    Fang Tang

    2016-01-01

    Full Text Available The aim of this study was to apply the reference-scaled average bioequivalence (RSABE approach to evaluate the bioequivalence of 2 formulations of agomelatine, and to investigate the pharmacokinetic properties of agomelatine in Chinese healthy male subjects. This was performed in a single-dose, randomized-sequence, open-label, four-way crossover study with a one-day washout period between doses. Healthy Chinese males were randomly assigned to receive 25 mg of either the test or reference formulation. The formulations were considered bioequivalent if 90% confidence intervals (CIs for the log-transformed ratios and ratio of geometric means (GMR of AUC and Cmax of agomelatine were within the predetermined bioequivalence range based on RSABE method. Results showed that both of the 90% CIs for the log-transformed ratios of AUC and Cmax of 7-desmethyl-agomelatine and 3-hydroxy-agomelatine were within the predetermined bioequivalence range. The 90% CIs for natural log-transformed ratios of Cmax, AUC0–t and AUC0–∞ of agomelatine (104.42–139.86, 101.33–123.83 and 97.90–117.94 were within the RSABE acceptance limits, and 3-hydroxy-agomelatine (105.55–123.03, 101.95–109.10 and 101.72–108.70 and 7-desmethyl-agomelatine (104.50–125.23, 102.36–111.50 and 101.62–110.64 were within the FDA bioequivalence definition intervals (0.80–1.25 for AUC and 0.75–1.33 for Cmax. The RSABE approach was successful in evaluating the bioequivalence of these two formulations.

  18. Influence of the Thomson effect on the pulse heating of high-current electrical contacts

    Science.gov (United States)

    Merkushev, A. G.; Pavleino, M. A.; Pavleino, O. M.; Pavlov, V. A.

    2014-09-01

    Pulse heating of high-current contacts is notable for the presence of considerable temperature gradients in the contact area, which cause the Thomson effect—the appearance of thermoelectric currents. The amount of this effect against conventional Joule heat release is quantitatively estimated. Pulse heating of electrical contacts is numerically simulated with the use of the Comsol program package. It is demonstrated that thermoelectric currents make a negligible contribution to heating in the case of copper contacts.

  19. Experimental Research On Gas Injection High Temperature Heat Pump With An Economizer

    OpenAIRE

    He, Yongning; Lei JIN; Cao, Feng; Chen, Shengkun

    2014-01-01

    Gas injection technology is often used in cold regions to solve heat pump’s low heating capacity and high discharge temperature at low ambient temperature. Injecting gas into port opened at specific position of compressor could increase mass flow rate of compressor and total heating capacity of heat pump. Gas injection also changes compression ratio of compressor and decreases discharge temperature. An optimal gas injection pressure is got when the coefficient of performance reached to peak v...

  20. High Efficiency R-744 Commercial Heat Pump Water Heaters

    Energy Technology Data Exchange (ETDEWEB)

    Elbel, Dr. Stefan W.; Petersen, Michael

    2013-04-25

    The project investigated the development and improvement process of a R744 (CO2) commercial heat pump water heater (HPWH) package of approximately 35 kW. The improvement process covered all main components of the system. More specific the heat exchangers (Internal heat exchanger, Evaporator, Gas cooler) as well as the expansion device and the compressor were investigated. In addition, a comparison to a commercially available baseline R134a unit of the same capacity and footprint was made in order to compare performance as well as package size reduction potential.

  1. Non-Fourier Heat Conduction Effects During High-Energy Beam Metalworking

    Institute of Scientific and Technical Information of China (English)

    张海泉; 张彦华; 赵海燕

    2004-01-01

    Non-Fourier heat conduction induced by ultrafast heating of metals with a high-energy density beam was analyzed. The non-Fourier effects during high heat flux heating were illustrated by comparing the transient temperature response to different heat flux and material relaxation times. Based on the hyperbolic heat conduction equation for the non-Fourier heat conduction law, the equation was solved using a hybrid method combining an analytical solution and numerical inversion of the Laplace transforms for a semi-infinite body with the heat flux boundary. Analysis of the temperature response and distribution led to a criterion for the applicability of the non-Fourier heat conduction law. The results show that at a relatively large heat flux, such as greater than 108 W/cm2, the heat-affected zone in the metal material experiences a strong thermal shock as the non-Fourier effects cause a large step increase in the surface temperature. The results provide a method for analyzing transient heat conduction problems using a high-energy density beam, such as electron beam deep penetration welding.

  2. Development of high-aspect-ratio microchannel heat exchanger based on multi-tool milling process

    Institute of Scientific and Technical Information of China (English)

    潘敏强; 李金恒; 汤勇

    2008-01-01

    A high-aspect-ratio microchannel heat exchanger based on multi-tool milling process was developed. Several slotting cutters were stacked together for simultaneously machining several high-aspect-ratio microchannels with manifold structures. On the basis of multi-tool milling process, the structural design of the manifold side height, microchannel length, width, number, and interval were analyzed. The heat transfer performances of high-aspect-ratio microchannel heat exchangers with two different manifolds were investigated by experiments, and the influencing factors were analyzed. The results indicate that the magnitude of heat transfer area per unit volume dominates the heat transfer performances of plate-type micro heat exchanger, while the velocity distribution between microchannels has little effects on the heat transfer performances.

  3. Apparatus for measuring high-flux heat transfer in radiatively heated compact exchangers

    Science.gov (United States)

    Olson, Douglas A.

    1989-01-01

    An apparatus is described which can deliver uniform heat flux densities of up to 80 W/sq cm over an area 7.8 cm x 15.2 cm for use in measuring the heat transfer and pressure drop in thin (6 mm or less), compact heat exchangers. Helium gas at flow rates of 0 to 40 kg/h and pressures to 6.9 MPa (1000 psi) is the working fluid. The instrumentation used in the apparatus and the methods for analyzing the data is described. The apparatus will be used initially to test the performance of prototype cooling jackets for the engine struts of the National Aerospace Plane (NASP).

  4. Heat Transfer Characteristics in High Power LED Packaging

    OpenAIRE

    Chi-Hung Chung; Kai-Shing Yang; Kuo-Hsiang Chien; Ming-Shan Jeng; Ming-Tsang Lee

    2014-01-01

    This study uses the T3Ster transient thermal resistance measuring device to investigate the effects to heat transfer performances from different LED crystal grains, packaging methods and heat-sink substrates through the experimental method. The experimental parameters are six different types of LED modules that are made alternatively with the crystal grain structure, the die attach method and the carrying substrate. The crystal grain structure includes the lateral type, flip chip type and ver...

  5. Effect of Heat Treatment on Mechanical Property of High Cr-W Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Liu Jianping; Li Lixia

    2007-01-01

    The microstructure of high Cr-W cast iron after heat treatment were analyzed, and the effect of various heat treatment temperature and time on mechanical properties of high Cr-W cast iron were studied, and the best process parameter of heat treatment was provided in this paper. The results show that the heat treatment can improve the mechanical property of high Cr-W cast iron, and higher synthetic mechanical property of high Cr-W cast iron can be obtained when treated with normalization at 980℃ for 2h and tempered at 400℃ for 2h.

  6. The value of time-averaged serum high-sensitivity C-reactive protein in prediction of mortality and dropout in peritoneal dialysis patients.

    Science.gov (United States)

    Liu, Shou-Hsuan; Chen, Chao-Yu; Li, Yi-Jung; Wu, Hsin-Hsu; Lin, Chan-Yu; Chen, Yung-Chang; Chang, Ming-Yang; Hsu, Hsiang-Hao; Ku, Cheng-Lung; Tian, Ya-Chung

    2017-01-01

    C-reactive protein (CRP) is a useful biomarker for prediction of long-term outcomes in patients undergoing chronic dialysis. This observational cohort study evaluated whether the time-averaged serum high-sensitivity CRP (HS-CRP) level was a better predictor of clinical outcomes than a single HS-CRP level in patients undergoing peritoneal dialysis (PD). We classified 335 patients into three tertiles according to the time-averaged serum HS-CRP level and followed up regularly from January 2010 to December 2014. Clinical outcomes such as cardiovascular events, infection episodes, newly developed malignancy, encapsulating peritoneal sclerosis (EPS), dropout (death plus conversion to hemodialysis), and mortality were assessed. During a 5-year follow-up, 164 patients (49.0%) ceased PD; this included 52 patient deaths (15.5%), 100 patients (29.9%) who converted to hemodialysis, and 12 patients (3.6%) who received a kidney transplantation. The Kaplan-Meier survival analysis and log-rank test revealed a significantly worse survival accumulation in patients with high time-average HS-CRP levels. A multivariate Cox regression analysis revealed that a higher time-averaged serum HS-CRP level, older age, and the occurrence of cardiovascular events were independent mortality predictors. A higher time-averaged serum HS-CRP level, the occurrence of cardiovascular events, infection episodes, and EPS were important predictors of dropout. The receiver operating characteristic analysis verified that the value of the time-average HS-CRP level in predicting the 5-year mortality and dropout was superior to a single serum baseline HS-CRP level. This study shows that the time-averaged serum HS-CRP level is a better marker than a single baseline measurement in predicting the 5-year mortality and dropout in PD patients.

  7. Heat and fuel coupled operation of a high temperature polymer electrolyte fuel cell with a heat exchanger methanol steam reformer

    Science.gov (United States)

    Schuller, G.; Vázquez, F. Vidal; Waiblinger, W.; Auvinen, S.; Ribeirinha, P.

    2017-04-01

    In this work a methanol steam reforming (MSR) reactor has been operated thermally coupled to a high temperature polymer electrolyte fuel cell stack (HT-PEMFC) utilizing its waste heat. The operating temperature of the coupled system was 180 °C which is significantly lower than the conventional operating temperature of the MSR process which is around 250 °C. A newly designed heat exchanger reformer has been developed by VTT (Technical Research Center of Finland LTD) and was equipped with commercially available CuO/ZnO/Al2O3 (BASF RP-60) catalyst. The liquid cooled, 165 cm2, 12-cell stack used for the measurements was supplied by Serenergy A/S. The off-heat from the electrochemical fuel cell reaction was transferred to the reforming reactor using triethylene glycol (TEG) as heat transfer fluid. The system was operated up to 0.4 A cm-2 generating an electrical power output of 427 Wel. A total stack waste heat utilization of 86.4% was achieved. It has been shown that it is possible to transfer sufficient heat from the fuel cell stack to the liquid circuit in order to provide the needed amount for vaporizing and reforming of the methanol-water-mixture. Furthermore a set of recommendations is given for future system design considerations.

  8. High average power 1314 nm Nd:YLF laser, passively Q-switched with V:YAG

    CSIR Research Space (South Africa)

    Botha, RC

    2013-03-01

    Full Text Available Stellenbosch University, P/Bag X1, Matieland 7602, South Africa 3National Laser Centre, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001, South Africa 4Physics Department, Carl von Ossietzky University, Oldenburg 26111, Germany 5...-shifted to the 1.5 μm region, which is useful for applications requiring eye-safe operation at high powers, such as Lidar and free-space optical com- munication [1]. Furthermore, 1314.0 nm (specifically the 657.0 nm harmonic) is required to probe the relevant...

  9. Interpreting Changes over Time in High School Average ACT® College Readiness Assessment Composite Scores and ACT College Readiness Benchmark Attainment Rates. ACT Research Report Series, 2013 (9)

    Science.gov (United States)

    Sawyer, Richard

    2013-01-01

    Education officials and journalists frequently track changes over time in the average ACT® College Readiness Assessment Composite scores and ACT College Readiness Benchmark attainment rates of individual high schools. Using standard statistical methods, I examined how often changes in these statistics are unambiguously positive or negative, rather…

  10. Boiling Heat Transfer in High Temperature Generator of Absorption Chiller/Heater

    Science.gov (United States)

    Furukawa, Masahiro; Enomoto, Eiichi; Sekoguchi, Kotohiko

    The heat transfer performance of forced convective boiling was tested using a high temperature generator of absorption chiller/heater, the rear furnace wall of which was composed of two different surfaces; i. e., plain and sprayed heated surfaces. These two surfaces were bisymmetrically set. Wall surface temperatures of both the fire and fluid sides were measured at three locations along the upward flow direction in each heated surface for determining the heat flux and heat transfer coefficient. Nickel-chromium and alumina were employed as the spray materials. The test results show that the sprayed surface can yield a marked elevation in the heat transfer performance due to boiling on the plain surface. Therefore the level of heated surface temperature is largely reduced by means of the spraying surface treatment. This implies that the spraying would much improve a corrosive condition of the heated surface.

  11. Radiant heat transfer network in the simulated protective clothing ; System under high heat flux

    NARCIS (Netherlands)

    Fukazawa, T.; Hartog, E.A. den; Daanen, H.A.M.; Penders-van Elk, N.; Tochihara, Y.; Havenith, G.

    2005-01-01

    A radiant network model was developed for design of the protective clothing system against solar and infrared radiative heat flux. A one-dimensional model was employed in the present study, because the aim of this study was to obtain precise temperature distribution through the system with use of a

  12. 2D Chaos in the Interaction of Inflation and Unemployment: Moving Averages and the Modeling of High Frequency Macrodynamics

    Directory of Open Access Journals (Sweden)

    Peter Flaschel

    2014-01-01

    Full Text Available The paper argues that applicable macro is high frequency macro and the data generating process is therefore to be modeled in continuous time. It exemplifies this with a misuse of a 2D period model of monetarist type which becomes extremely overshooting, allowing for routes to “chaos,” when iterated at low frequencies. Instead of such low frequency procedures, we augment the model by a Keynesian feedback chain (the real rate of interest channel to introduce local instability into the model. We also introduce heterogeneous opinion dynamics into it. The implied 4D dynamics are made bounded thereby, but seem to allow only complex limit cycles, with no transition towards strange attractors anymore.

  13. Institute for High Heat Flux Removal (IHHFR). Phases I, II, and III

    Energy Technology Data Exchange (ETDEWEB)

    Boyd, Ronald D. [Prairie View A& M Univ., TX (United States)

    2014-08-31

    The IHHFR focused on interdisciplinary applications as it relates to high heat flux engineering issues and problems which arise due to engineering systems being miniaturized, optimized, or requiring increased high heat flux performance. The work in the IHHFR focused on water as a coolant and includes: (1) the development, design, and construction of the high heat flux flow loop and facility; (2) test section development, design, and fabrication; and, (3) single-side heat flux experiments to produce 2-D boiling curves and 3-D conjugate heat transfer measurements for single-side heated test sections. This work provides data for comparisons with previously developed and new single-side heated correlations and approaches that address the single-side heated effect on heat transfer. In addition, this work includes the addition of single-side heated circular TS and a monoblock test section with a helical wire insert. Finally, the present work includes: (1) data base expansion for the monoblock with a helical wire insert (only for the latter geometry), (2) prediction and verification using finite element, (3) monoblock model and methodology development analyses, and (4) an alternate model development for a hypervapotron and related conjugate heat transfer controlling parameters.

  14. Electricity demand profile with high penetration of heat pumps in Nordic area

    DEFF Research Database (Denmark)

    Liu, Zhaoxi; Wu, Qiuwei; Nielsen, Arne Hejde

    2013-01-01

    This paper presents the heat pump (HP) demand profile with high HP penetration in the Nordic area in order to achieve the carbon neutrality power system. The calculation method in the European Standard EN14825 was used to estimate the HP electricity demand profile. The study results show there wi......This paper presents the heat pump (HP) demand profile with high HP penetration in the Nordic area in order to achieve the carbon neutrality power system. The calculation method in the European Standard EN14825 was used to estimate the HP electricity demand profile. The study results show...... there will be high power demand from HPs and the selection of supplemental heating for heat pumps has a big impact on the peak electrical power load of heating. The study in this paper gives an estimate of the scale of the electricity demand with high penetration of heat pumps in the Nordic area....

  15. Urban physiology: city ants possess high heat tolerance.

    Directory of Open Access Journals (Sweden)

    Michael J Angilletta

    Full Text Available Urbanization has caused regional increases in temperature that exceed those measured on a global scale, leading to urban heat islands as much as 12 degrees C hotter than their surroundings. Optimality models predict ectotherms in urban areas should tolerate heat better and cold worse than ectotherms in rural areas. We tested these predications by measuring heat and cold tolerances of leaf-cutter ants from South America's largest city (São Paulo, Brazil. Specifically, we compared thermal tolerances of ants from inside and outside of the city. Knock-down resistance and chill-coma recovery were used as indicators of heat and cold tolerances, respectively. Ants from within the city took 20% longer to lose mobility at 42 degrees C than ants from outside the city. Interestingly, greater heat tolerance came at no obvious expense of cold tolerance; hence, our observations only partially support current theory. Our results indicate that thermal tolerances of some organisms can respond to rapid changes in climate. Predictive models should account for acclimatory and evolutionary responses during climate change.

  16. Determination of the fission-neutron averaged cross sections of some high-energy threshold reactions of interest for reactor dosimetry

    CERN Document Server

    Arribere, M A; Ribeiro-Guevara, S; Korochinsky, S; Blostein, J J

    2003-01-01

    For three high threshold reactions, we have measured the cross sections averaged over a sup 2 sup 3 sup 5 U fission neutron spectrum. The measured reactions, and corresponding averaged cross sections found, are: sup 1 sup 2 sup 7 I(n,2n) sup 1 sup 2 sup 6 I, (1.36+-0.12) mb; sup 9 sup 0 Zr(n,2n) sup 8 sup 9 sup m Zr, (13.86+-0.83) mu b; and sup 5 sup 8 Ni(n,d+np+pn) sup 5 sup 7 Co, (274+-15) mu b; all referred to the well known standard of (111+-3) mb for the sup 5 sup 8 Ni(n,p) sup 5 sup 8 sup m sup + sup g Co averaged cross section. The measured cross sections are of interest in nuclear engineering for the characterization of the fast neutron component in the energy distribution of reactor neutrons. (author)

  17. Heat-transfer correlations for high-finned tubes in staggered arrangements

    Energy Technology Data Exchange (ETDEWEB)

    Hashizume, Kenichi [Hiroshima Inst. of Tech. (Japan). Dept. of Mechanical Engineering

    1995-12-31

    Existing correlations are reviewed for heat transfer of high-finned tubes in staggered arrangements and compared with published experimental data. These data include those using tubes for air-coolers (AC) and for heat-recovery heat exchangers in the high-temperature region (HRHX). Comparisons showed that none of the correlations can predict experimental data for both AC and for HRHX. Therefore a new correlation is proposed which can predict almost all data within 10 percent.

  18. COMPARISON OF COOLING SCHEMES FOR HIGH HEAT FLUX COMPONENTS COOLING IN FUSION REACTORS

    Directory of Open Access Journals (Sweden)

    Phani Kumar Domalapally

    2015-04-01

    Full Text Available Some components of the fusion reactor receives high heat fluxes either during the startup and shutdown or during the operation of the machine. This paper analyzes different ways of enhancing heat transfer using helium and water for cooling of these high heat flux components and then conclusions are drawn to decide the best choice of coolant, for usage in near and long term applications.

  19. Thermal barrier coatings (TBC's) for high heat flux thrust chambers

    Science.gov (United States)

    Bradley, Christopher M.

    -section components has become critical, but at the same time the service conditions have put our best alloy systems to their limits. As a result, implementation of cooling holes and thermal barrier coatings are new advances in hot-section technologies now looked at for modifications to reach higher temperature applications. Current thermal barrier coatings used in today's turbine applications is known as 8%yttria-stabilized zirconia (YSZ) and there are no coatings for current thrust chambers. Current research is looking at the applicability of 8%yttria-stabilized hafnia (YSH) for turbine applications and the implementation of 8%YSZ onto thrust chambers. This study intends to determine if the use of thermal barrier coatings are applicable for high heat flux thrust chambers using industrial YSZ will be advantageous for improvements in efficiency, thrust and longer service life by allowing the thrust chambers to be used more than once.

  20. A Geographic Method for High Resolution Spatial Heat Planning

    DEFF Research Database (Denmark)

    Nielsen, Steffen

    2014-01-01

    In many countries, district heating (DH) covers a large share of the heat market. In these countries, the best locations for DH systems have already been found. Therefore, the challenge for these countries is to find expansion potentials for existing DH. The expansion to less ideal areas requires...... more detailed modelling that takes the geographic placement of buildings and the differences among DH systems into account. In the present article, a method for assessing the costs of DH expansions has been developed. The method was applied in a geographic information system (GIS) model that consists...... of three parts and assesses the costs of heat production, distribution, and transmission. The model was also applied to an actual case in order to show how it can be used. The model shows many improvements in the method for the assessment of distribution costs and transmission costs. Most notable...

  1. Heat treatment of colostrum increases immunoglobulin G absorption efficiency in high-, medium-, and low-quality colostrum.

    Science.gov (United States)

    Gelsinger, S L; Gray, S M; Jones, C M; Heinrichs, A J

    2014-01-01

    Previous studies with heat-treated colostrum fed to neonatal calves have consistently used average-quality colostrum. Studies have not compared colostrum across a range of immunoglobulin levels. This study was conducted to investigate IgG absorption in neonatal dairy calves using colostrum of various qualities. Colostrum from the Pennsylvania State University dairy was collected over 2 yr and sorted into high, medium, and low quality based on colostrometer measurement. Colostrum within each category was pooled to create 3 unique, uniform batches. Half of each batch was frozen to be fed without heat treatment. The second half of each batch was heat treated at 60°C for 30min. This process was conducted in September 2011, and repeated in June 2012. Colostrum treatments were analyzed for standard plate count, coliforms, noncoliform gram-negative bacteria, and total IgG concentration. Plasma samples were collected from 145 calves 48h after birth and analyzed for IgG1, IgG2, total protein, and hematocrit. Colostrum quality (high, medium, or low), treatment (unheated or heat treated), and their interactions were analyzed as fixed effects, with year included as a random effect. Heat treatment significantly reduced all types of bacteria and IgG concentration. Plasma IgG concentration at 48h increased linearly with the concentration of IgG in the colostrum that was consumed. Heat treatment of colostrum increased plasma IgG concentration by 18.4% and apparent efficiency of absorption by 21.0%. Results of this study suggest that heat treatment of colostrum containing approximately 50 to 100mg IgG/mL increases absorption of IgG from colostrum.

  2. Solar wind effect on Joule heating in the high-latitude ionosphere

    Science.gov (United States)

    Cai, L.; Aikio, A. T.; Nygrén, T.

    2014-12-01

    The effect of solar wind on several electrodynamic parameters, measured simultaneously by the European Incoherent Scatter (EISCAT) radars in Tromsø (TRO, 66.6° cgmLat) and on Svalbard (ESR, 75.4° cgmLat), has been evaluated statistically. The main emphasis is on Joule heating rate QJ, which has been estimated by taking into account the neutral wind. In addition, a generally used proxy QE, which is the Pedersen conductance times the electric field squared, has been calculated. The most important findings are as follows. (i) The decrease in Joule heating in the afternoon-evening sector due to winds reported by Aikio et al. (2012) requires southward interplanetary magnetic field (IMF) conditions and a sufficiently high solar wind electric field. The increase in the morning sector takes place for all IMF directions within a region where the upper E neutral wind has a large equatorward component and the F region plasma flow is directed eastward. (ii) At ESR, an afternoon hot spot of Joule heating centered typically at 14-15 magnetic local time (MLT) is observed during all IMF conditions. Enhanced Pedersen conductances within the hot spot region are observed only for the IMF Bz + /By- conditions, and the corresponding convection electric field values within the hot spot are smaller than during the other IMF conditions. Hence, the hot spot represents a region of persistent magnetospheric electromagnetic energy input, and the median value is about 3 mW/m2. (iii) For the southward IMF conditions, the MLT-integrated QE for By- is twice the value for By+ at TRO. This can plausibly be explained by the higher average solar wind electric field values for By-.

  3. High spatial- and temporal-resolution anthropogenic heat discharge estimation in Los Angeles County, California.

    Science.gov (United States)

    Zheng, Yuanfan; Weng, Qihao

    2017-07-22

    Anthropogenic heat flux (Qf), which originates through energy consumption from buildings, industrial plants, vehicle exhausts, and human metabolism releases, is an important component in the urban Surface Energy Balance (SEB) system, and is key to understanding of many urban environmental issues. The present study provided a hybrid Qf modeling approach, which combined the inventory and GIS approach to create a 365-day hourly Qf profile at 120 m spatial resolution in Los Angeles County, California, USA. Qf was estimated by separate calculation of heat release from buildings, traffics, and human metabolism, respectively. The results indicated that Qf showed different magnitudes and diurnal patterns between workdays (dual-peak shape) and weekends/holidays, and also varied with seasons, and land use types. Qf yielded the highest values in the summer workdays, with its maximum value of 7.76 w/m(2). Qf in hot summer workdays was obviously higher than that in the average summer workdays, which caused by higher demands for space cooling in buildings, and can reach 8.14 w/m(2) at maximum. Building energy consumption was identified as the dominant contributor to the Qf in Downtown Los Angeles, which was found to have the largest mean Qf throughout the year among all neighborhoods. It can be concluded that Qf in the downtown was more significant in workdays than that in non-workdays, and its maximum value can reach 100 w/m(2). It is suggested that our approach may have wider applicability for Qf estimation in large areas compared with the existing studies, as all the data used were available to the public. A high spatial and temporal Qf profile, which can readily be incorporated into urban energy balance and Urban Heat Island (UHI) studies, provides valuable data and information for pertinent government agencies and researchers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. The features of steel surface hardening with high energy heating by high frequency currents and shower cooling

    Science.gov (United States)

    Ivancivsky, V. V.; Skeeba, V. Yu; Bataev, I. A.; Lobanov, D. V.; Martyushev, N. V.; Sakha, O. V.; Khlebova, I. V.

    2016-11-01

    The paper examines the process of surface hardening of steel 45 with the help of high energy heating by high frequency currents with simultaneous shower water cooling. We theoretically justified and experimentally proved a possibility of liquid phase forming in the course of heating not on the surface, but in the depth of the surface layer.

  5. Development of laser diode-pumped high average power solid-state laser for the pumping of Ti:sapphire CPA system

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, Yoichiro; Tei, Kazuyoku; Kato, Masaaki; Niwa, Yoshito; Harayama, Sayaka; Oba, Masaki; Matoba, Tohru; Arisawa, Takashi; Takuma, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    Laser diode pumped all solid state, high repetition frequency (PRF) and high energy Nd:YAG laser using zigzag slab crystals has been developed for the pumping source of Ti:sapphire CPA system. The pumping laser installs two main amplifiers which compose ring type amplifier configuration. The maximum amplification gain of the amplifier system is 140 and the condition of saturated amplification is achieved with this high gain. The average power of fundamental laser radiation is 250 W at the PRF of 200 Hz and the pulse duration is around 20 ns. The average power of second harmonic is 105 W at the PRF of 170 Hz and the pulse duration is about 16 ns. The beam profile of the second harmonic is near top hat and will be suitable for the pumping of Ti:sapphire laser crystal. The wall plug efficiency of the laser is 2.0 %. (author)

  6. Heat Transfer Characteristics in High Power LED Packaging

    Directory of Open Access Journals (Sweden)

    Chi-Hung Chung

    2014-03-01

    Full Text Available This study uses the T3Ster transient thermal resistance measuring device to investigate the effects to heat transfer performances from different LED crystal grains, packaging methods and heat-sink substrates through the experimental method. The experimental parameters are six different types of LED modules that are made alternatively with the crystal grain structure, the die attach method and the carrying substrate. The crystal grain structure includes the lateral type, flip chip type and vertical type. The die attach method includes silver paste and the eutectic structure. The carrying substrates are aluminum oxide (Alumina and aluminum nitride (AIN ceramic substrates and metal core PCB (MCPCB. The experimental results show that, under the conditions of the same crystal grain and die attach method, the thermal resistance values for the AIN substrate and the Alumina substrate are 2.1K/W and 5.1K/W, respectively and the total thermal resistance values are 7.3K/W and 10.8K/W. Compared to the Alumina substrate, the AIN substrate can effectively lower the total thermal resistance value by 32.4%. This is because the heat transfer coefficient of the AIN substrate is higher than that of the Alumina substrate, thus effectively increasing its thermal conductivity. In addition, under the conditions of the same crystal grain and the same substrate, the packaging methods are using silver paste and the eutectic structure for die attach. Their thermal resistance values are 5.7K/W and 2.7K/W, respectively, with a variance of 3K/W. Comparisons of the crystal grain structure show that the thermal resistance for the flip chip type is lower than that of the traditional lateral type by 0.9K/W. This is because the light emitting layer of the flip chip crystal grain is closer to the heat-sink substrate, shortening the heat dissipation route, and thus lowering the thermal resistance value. For the total thermal resistance, the crystal grain structure has a lesser

  7. Thermal analysis of heat and power plant with high temperature reactor and intermediate steam cycle

    Directory of Open Access Journals (Sweden)

    Fic Adam

    2015-03-01

    Full Text Available Thermal analysis of a heat and power plant with a high temperature gas cooled nuclear reactor is presented. The main aim of the considered system is to supply a technological process with the heat at suitably high temperature level. The considered unit is also used to produce electricity. The high temperature helium cooled nuclear reactor is the primary heat source in the system, which consists of: the reactor cooling cycle, the steam cycle and the gas heat pump cycle. Helium used as a carrier in the first cycle (classic Brayton cycle, which includes the reactor, delivers heat in a steam generator to produce superheated steam with required parameters of the intermediate cycle. The intermediate cycle is provided to transport energy from the reactor installation to the process installation requiring a high temperature heat. The distance between reactor and the process installation is assumed short and negligable, or alternatively equal to 1 km in the analysis. The system is also equipped with a high temperature argon heat pump to obtain the temperature level of a heat carrier required by a high temperature process. Thus, the steam of the intermediate cycle supplies a lower heat exchanger of the heat pump, a process heat exchanger at the medium temperature level and a classical steam turbine system (Rankine cycle. The main purpose of the research was to evaluate the effectiveness of the system considered and to assess whether such a three cycle cogeneration system is reasonable. Multivariant calculations have been carried out employing the developed mathematical model. The results have been presented in a form of the energy efficiency and exergy efficiency of the system as a function of the temperature drop in the high temperature process heat exchanger and the reactor pressure.

  8. Alternatives Generation and Analysis for Heat Removal from High Level Waste Tanks

    Energy Technology Data Exchange (ETDEWEB)

    WILLIS, W.L.

    2000-06-15

    This document addresses the preferred combination of design and operational configurations to provide heat removal from high-level waste tanks during Phase 1 waste feed delivery to prevent the waste temperature from exceeding tank safety requirement limits. An interim decision for the preferred method to remove the heat from the high-level waste tanks during waste feed delivery operations is presented herein.

  9. Homogeneous heating of a sample space by a modified heating assembly in a belt-type high-pressure apparatus.

    Science.gov (United States)

    Miyakawa, M; Taniguchi, T

    2015-02-01

    To create homogeneous heating in the sample space in a belt-type high-pressure apparatus, modified heating assemblies under pressure of 2.5 GPa and temperature up to 1700 °C were examined. Counterbores (with several diameters) were made at both ends of a cylindrical graphite heater to suppress the temperature gradient along the cylindrical axis of the heater. Temperature distributions within the heaters were measured by thermocouples and geothermometers. Both sets of measurements revealed that the temperature distribution in the sample space (6.9 mm outside diameter/12 mm length) was homogenized (i.e., variation of less than 10 °C under heating at 1700 °C) by optimizing the heater shape.

  10. Electron Cyclotron Resonance Heating of a High-Density Plasma

    DEFF Research Database (Denmark)

    Hansen, F. Ramskov

    1986-01-01

    Various schemes for electron cyclotron resonance heating of tokamak plasmas with the ratio of electron plasma frequency to electron cyclotron frequency, "»pe/^ce* larger than 1 on axis, are investigated. In particular, a mode conversion scheme is investigated using ordinary waves at the fundamental...

  11. High temperature thermographic measurements of laser heated silica

    Energy Technology Data Exchange (ETDEWEB)

    Elhadj, S; Yang, S T; Matthews, M J; Cooke, D J; Bude, J D; Johnson, M; Feit, M; Draggoo, V; Bisson, S E

    2009-11-02

    In situ spatial and temporal surface temperature profiles of CO{sub 2} laser-heated silica were obtained using a long wave infrared (LWIR) HgCdTe camera. Solutions to the linear diffusion equation with volumetric and surface heating are shown to describe the temperature evolution for a range of beam powers, over which the peak surface temperature scales linearly with power. These solutions were used with on-axis steady state and transient experimental temperatures to extract thermal diffusivity and conductivity for a variety of materials, including silica, spinel, sapphire, and lithium fluoride. Experimentally-derived thermal properties agreed well with reported values and, for silica, thermal conductivity and diffusivity are shown to be approximately independent of temperature between 300 and 2800K. While for silica our analysis based on a temperature independent thermal conductivity is shown to be accurate, for other materials studied this treatment yields effective thermal properties that represent reasonable approximations for laser heating. Implementation of a single-wavelength radiation measurement in the semi-transparent regime is generally discussed, and estimates of the apparent temperature deviation from the actual outer surface temperature are also presented. The experimental approach and the simple analysis presented yield surface temperature measurements that can be used to validate more complex physical models, help discriminate dominant heat transport mechanisms, and to predict temperature distribution and evolution during laser-based material processing.

  12. Geothermal Heat Pumps Score High Marks in Schools.

    Science.gov (United States)

    National Renewable Energy Lab (DOE).

    Geothermal heat pumps (GHPs) are showing their value in providing lower operating and maintenance costs, energy efficiency, and superior classroom comfort. This document describes what GHPs are and the benefits a school can garner after installing a GHP system. Three case studies are provided that illustrate these benefits. Finally, the Department…

  13. High temperature thermographic measurements of laser heated silica

    Science.gov (United States)

    Elhadj, Selim; Yang, Steven T.; Matthews, Manyalibo J.; Cooke, Diane J.; Bude, Jeffrey D.; Johnson, Michael; Feit, Michael; Draggoo, Vaughn; Bisson, Scott E.

    2009-10-01

    In situ spatial and temporal surface temperature profiles of CO2 laser-heated silica were obtained using a long wave infrared (LWIR) HgCdTe camera. Solutions to the linear diffusion equation with volumetric and surface heating are shown to describe the temperature evolution for a range of beam powers, over which the peak surface temperature scales linearly with power. These solutions were used with on-axis steady state and transient experimental temperatures to extract thermal diffusivity and conductivity for a variety of materials, including silica, spinel, sapphire, and lithium fluoride. Experimentally-derived thermal properties agreed well with reported values and, for silica, thermal conductivity and diffusivity are shown to be approximately independent of temperature between 300 and 2800K. While for silica our analysis based on a temperature independent thermal conductivity is shown to be accurate, for other materials studied this treatment yields effective thermal properties that represent reasonable approximations for laser heating. Implementation of a single-wavelength radiation measurement in the semi-transparent regime is generally discussed, and estimates of the apparent temperature deviation from the actual outer surface temperature are also presented. The experimental approach and the simple analysis presented yield surface temperature measurements that can be used to validate more complex physical models, help discriminate dominant heat transport mechanisms, and to predict temperature distribution and evolution during laser-based material processing.

  14. A dynamic aerodynamic resistance approach to calculate high resolution sensible heat fluxes in urban areas

    Science.gov (United States)

    Crawford, Ben; Grimmond, Sue; Kent, Christoph; Gabey, Andrew; Ward, Helen; Sun, Ting; Morrison, William

    2017-04-01

    Remotely sensed data from satellites have potential to enable high-resolution, automated calculation of urban surface energy balance terms and inform decisions about urban adaptations to environmental change. However, aerodynamic resistance methods to estimate sensible heat flux (QH) in cities using satellite-derived observations of surface temperature are difficult in part due to spatial and temporal variability of the thermal aerodynamic resistance term (rah). In this work, we extend an empirical function to estimate rah using observational data from several cities with a broad range of surface vegetation land cover properties. We then use this function to calculate spatially and temporally variable rah in London based on high-resolution (100 m) land cover datasets and in situ meteorological observations. In order to calculate high-resolution QH based on satellite-observed land surface temperatures, we also develop and employ novel methods to i) apply source area-weighted averaging of surface and meteorological variables across the study spatial domain, ii) calculate spatially variable, high-resolution meteorological variables (wind speed, friction velocity, and Obukhov length), iii) incorporate spatially interpolated urban air temperatures from a distributed sensor network, and iv) apply a modified Monte Carlo approach to assess uncertainties with our results, methods, and input variables. Modeled QH using the aerodynamic resistance method is then compared to in situ observations in central London from a unique network of scintillometers and eddy-covariance measurements.

  15. High-power ELF radiation generated by modulated HF heating of the ionosphere can cause Earthquakes, Cyclones and localized heating

    OpenAIRE

    De Aquino, Fran

    2011-01-01

    The High Frequency Active Auroral Research Program (HAARP) is currently the most important facility used to generate extremely low frequency (ELF) electromagnetic radiation in the ionosphere. In order to produce this ELF radiation the HAARP transmitter radiates a strong beam of high-frequency (HF) waves modulated at ELF. This HF heating modulates the electrons' temperature in the D region ionosphere and leads to modulated conductivity and a time-varying current which then radiates at the modu...

  16. High-power ELF radiation generated by modulated HF heating of the ionosphere can cause Earthquakes, Cyclones and localized heating

    OpenAIRE

    De Aquino, Fran

    2011-01-01

    The High Frequency Active Auroral Research Program (HAARP) is currently the most important facility used to generate extremely low frequency (ELF) electromagnetic radiation in the ionosphere. In order to produce this ELF radiation the HAARP transmitter radiates a strong beam of high-frequency (HF) waves modulated at ELF. This HF heating modulates the electrons' temperature in the D region ionosphere and leads to modulated conductivity and a time-varying current which then radiates at the modu...

  17. Experimental study on heat transfer augmentation for high heat flux removal in rib-roughened narrow channels

    Energy Technology Data Exchange (ETDEWEB)

    Islam, M.S.; Monde, Masanori [Saga Univ. (Japan); Hino, Ryutaro; Haga, Katsuhiro; Sudo, Yukio

    1997-07-01

    Frictional pressure drop and heat transfer performance in a very narrow rectangular channel having one-sided constant heat flux and repeated-ribs for turbulent flow have been investigated experimentally, and their experimental correlations were obtained using the least square method. The rib pitch-to-height ratios(p/k) were 10 and 20 while holding the rib height constant at 0.2mm, the Reynolds number(Re) from 2,414 to 98,458 under different channel heights of 1.2mm, 2.97mm, and 3.24mm, the rib height-to-channel equivalent diameter(k/De) of 0.03, 0.04, and 0.09 respectively. The results show that the rib-roughened surface augments heat transfer 2-3 times higher than that of the smooth surface with the expense of 2.8-4 times higher frictional pressure drop under Re=5000-10{sup 5}, p/k=10, and H=1.2mm. Experimental results obtained by channel height, H=1.2mm shows a little bit higher heat transfer and friction factor performance than the higher channel height, H=3.24mm. The effect of fin and consequently higher turbulence intensity are responsible for producing higher heat transfer rates. The obtained correlations could be used to design the cooling passages between the target plates to remove high heat flux up to 12MW/m{sup 2} generated at target plates in a high-intensity proton accelerator system. (author). 54 refs.

  18. High-frequency Heating Behavior of Veneer-based Composites: Modelling and Validation

    Directory of Open Access Journals (Sweden)

    Peixing Wei

    2014-04-01

    Full Text Available A one-dimensional theoretical heat and mass transfer model was developed for high-frequency (HF heating of veneer-based composites, such as laminated veneer lumber (LVL and plywood. This model was based on the basic principles of energy and mass conservation, momentum conservation of gas flow, and gas thermodynamic relations. The response variables, including temperature, gas pressure, and moisture content (MC, were linked to basic material properties, such as veneer density, thermal conductivity, permeability, and dielectric properties. Initial and boundary conditions for solving the governing equations were also considered. The model was further validated by experiments with veneer HF heating and LVL HF heating. The model predictions agreed well with the experimental results. During veneer HF heating, the inner veneer core layers had lower MC than the outer surface layers. Compared to conventional hot platen heating, HF heating was proven to be an efficient and robust method for manufacturing veneer-based composites.

  19. The value of time-averaged serum high-sensitivity C-reactive protein in prediction of mortality and dropout in peritoneal dialysis patients

    Directory of Open Access Journals (Sweden)

    Liu SH

    2017-08-01

    Full Text Available Shou-Hsuan Liu,1–3,* Chao-Yu Chen,1,* Yi-Jung Li,1,2 Hsin-Hsu Wu,1,2 Chan-Yu Lin,1 Yung-Chang Chen,1 Ming-Yang Chang,1 Hsiang-Hao Hsu,1 Cheng-Lung Ku,2,3 Ya-Chung Tian1 1Kidney Research Center, Department of Nephrology, Lin-Kou Chang Gung Memorial Hospital and Department of Medicine, 2Graduate Institute of Clinical Medical Sciences, 3Laboratory of Human Immunology and Infectious Diseases, Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taoyuan, Taiwan *These authors contributed equally to this work Purpose: C-reactive protein (CRP is a useful biomarker for prediction of long-term outcomes in patients undergoing chronic dialysis. This observational cohort study evaluated whether the time-averaged serum high-sensitivity CRP (HS-CRP level was a better predictor of clinical outcomes than a single HS-CRP level in patients undergoing peritoneal dialysis (PD. Patients and methods: We classified 335 patients into three tertiles according to the time-averaged serum HS-CRP level and followed up regularly from January 2010 to December 2014. Clinical outcomes such as cardiovascular events, infection episodes, newly developed malignancy, encapsulating peritoneal sclerosis (EPS, dropout (death plus conversion to hemodialysis, and mortality were assessed. Results: During a 5-year follow-up, 164 patients (49.0% ceased PD; this included 52 patient deaths (15.5%, 100 patients (29.9% who converted to hemodialysis, and 12 patients (3.6% who received a kidney transplantation. The Kaplan–Meier survival analysis and log-rank test revealed a significantly worse survival accumulation in patients with high time-average HS-CRP levels. A multivariate Cox regression analysis revealed that a higher time-averaged serum HS-CRP level, older age, and the occurrence of cardiovascular events were independent mortality predictors. A higher time-averaged serum HS-CRP level, the occurrence of cardiovascular events, infection episodes, and EPS were

  20. The impact of including children with intellectual disability in general education classrooms on the academic achievement of their low-, average-, and high-achieving peers.

    Science.gov (United States)

    Sermier Dessemontet, Rachel; Bless, Gérard

    2013-03-01

    This study aimed at assessing the impact of including children with intellectual disability (ID) in general education classrooms with support on the academic achievement of their low-, average-, and high-achieving peers without disability. A quasi-experimental study was conducted with an experimental group of 202 pupils from classrooms with an included child with mild or moderate ID, and a control group of 202 pupils from classrooms with no included children with special educational needs (matched pairs sample). The progress of these 2 groups in their academic achievement was compared over a period of 1 school year. No significant difference was found in the progress of the low-, average-, or high-achieving pupils from classrooms with or without inclusion. The results suggest that including children with ID in primary general education classrooms with support does not have a negative impact on the progress of pupils without disability.

  1. A study on multifunction heat pipe type high efficient adsorption refrigerator using compound adsorbent-ammonia

    Institute of Scientific and Technical Information of China (English)

    LU Zisheng; WANG Ruzhu; WANG Liwei; CHEN Chuanjuan

    2006-01-01

    A multifunction heat pipe adsorption refrigerator is designed, which uses solidified compound adsorbent of CaCl2 and activated carbon as adsorbent. Two work conditions, ice-maker driven by the exhaust heat from diesel engine and air-condi- tioning powered by solar energy, are studied. SCP (specific cooling power) and COP (coefficient of per- formance) for different conditions are analyzed. The optimum average SCP and COP for the refrigerator powered by waste heat of diesel engine are 770.4 W/kg and 0.39 at about -20℃ evaporating tem- perature. The optimum average SCP and COP for the refrigerator powered by solar energy are 524.2 W/kg and 0.27 at about 5.6℃ evaporating tempera- ture.

  2. Investigation on repetition rate and pulse duration influences on ablation efficiency of metals using a high average power Yb-doped ultrafast laser

    Directory of Open Access Journals (Sweden)

    Lopez J.

    2013-11-01

    Full Text Available Ultrafast lasers provide an outstanding processing quality but their main drawback is the low removal rate per pulse compared to longer pulses. This limitation could be overcome by increasing both average power and repetition rate. In this paper, we report on the influence of high repetition rate and pulse duration on both ablation efficiency and processing quality on metals. All trials have been performed with a single tunable ultrafast laser (350 fs to 10ps.

  3. Highly efficient heat recovery system for phosphoric acid fuel cells used for cooling telecommunication equipment

    Science.gov (United States)

    Ishizawa, Maki; Okada, Shigeru; Yamashita, Takashi

    To protect the global environment by using energy more efficiently, NTT is developing a phosphoric acid fuel cell (PAFC) energy system for telecommunication cogeneration systems. Fuel cells are used to provide electrical power to telecommunication equipment and the heat energy is used by absorption refrigerators to cool the telecommunication rooms throughout the year. We have recently developed a highly efficient system for recovering heat and water from the exhaust gases of a 200-kW (rated power) fuel cell. It is composed of a shell-and-tube type heat exchanger to recover high-temperature heat and a direct-contact cooler to recover the water efficiently and simply. The reformer and cathode exhaust gases from the fuel cell are first supplied to the heat exchanger and then to the cooler. The high-temperature (85-60°C) heat can be recovered, and the total efficiency including the heat recovered from the fuel-cell stack coolant can be improved by supplying the recovered heat to the dual-heat-input absorption refrigerator. The water needed for operating the fuel cell is also recovered from the exhaust gases. We are currently applying this heat and water recovery system to the PC25C-type fuel cell. Maximum total efficiency including electrical power efficiency is estimated to be 78% at the rated power of 200 kW: composed of 17% heat recovery for the fuel-cell stack coolant, 21% from the exhaust gas by improving the heat exchanger, and 40% from electrical conversion. Next, we plan to evaluate the usefulness of this heat recovery system for cooling telecommunication equipment.

  4. High effectiveness liquid droplet/gas heat exchanger for space power applications

    Science.gov (United States)

    Bruckner, A. P.; Mattick, A. T.

    A high-effectiveness liquid droplet/gas heat exchanger (LDHX) concept for thermal management in space is described. Heat is transferred by direct contact between fine droplets (≈ 100-300 μm dia.) of a suitable low vapor pressure liquid and an inert working gas. Complete separation of the droplet and gas media in the zero-g environment is accomplished by configuring the LDHX as a vortex chamber. The large heat transfer area presented by the small droplets permits heat exchanger effectiveness of 0.9-0.95 in a compact, lightweight geometry which avoids many of the limitations of conventional plate and fin or tube and shell heat exchangers, such as their tendency toward single point failure. The application of the LDHX in a high temperature Brayton cycle is discussed to illustrate the performance and operational characteristics of this new heat exchanger concept.

  5. Investigations on the heating effect of PE-LD induced by high-intensity focused ultrasound.

    Science.gov (United States)

    Oehm, Lukas; Bach, Sascha; Majschak, Jens-Peter

    2016-08-01

    High-intensity focused ultrasound is widely applied in tissue treatment as well as for heating of solid polymer materials. Previous studies investigating the heating effect in polymer materials utilized sound transmission through water or other fluids at low HIFU power. In this study, the ultrasonic transducer possesses a solid sound conductor made of aluminum and a high HIFU power of above 100W was applied to heat solid PE-LD samples. Temperature measurements were performed by calibrated non-invasive infrared thermal imaging. A strong heating effect with heating above melting temperature and evaporation temperature within less than 1s of irradiation was observed. Furthermore, the acoustic coupling defined by the force applied by the ultrasonic applicator to the polymer material was found to be fundamental to induce the heating effect. This investigation reveals HIFU for new applications in the field of polymer processing.

  6. High effectiveness liquid droplet/gas heat exchanger for space power applications

    Science.gov (United States)

    Bruckner, A. P.; Mattick, A. T.

    1983-01-01

    A high-effectiveness liquid droplet/gas heat exchanger (LDHX) concept for thermal management in space is described. Heat is transferred by direct contact between fine droplets (approximately 100-300 microns in diameter) of a suitable low vapor pressure liquid and an inert working gas. Complete separation of the droplet and gas media in the zero-g environment is accomplished by configuring the LDHX as a vortex chamber.The large heat transfer area presented by the small droplets permits heat exchanger effectiveness of 0.9-0.95 in a compact, lightweight geometry which avoids many of the limitations of conventional plate and fin or tube and shell heat exchangers, such as their tendency toward single point failure. The application of the LDHX in a high temperature Brayton cycle is discussed to illustrate the performance and operational characteristics of this new heat exchanger concept.

  7. High Performance Cascading Adsorption Refrigeration Cycle with Internal Heat Recovery Driven by a Low Grade Heat Source Temperature

    Directory of Open Access Journals (Sweden)

    Yuki Ueda

    2009-11-01

    Full Text Available This paper presents the performance of an advanced cascading adsorption cycle that utilizes a driven heat source temperature between 90–130 ºC. The cycle consists of four beds that contain silica gel as an adsorber fill. Two of the beds work in a single stage cycle that is driven by an external heat source, while the other two beds work in a mass recovery cycle that is driven by waste heat of sensible and adsorption heat of the high temperature cycle. The performances, in terms of the coefficient of performance (COP and the specific cooling power (SCP, are compared with conventional cascading-without-mass-recovery and single-stage cycles. The paper also presents the effect of the adsorbent mass on performance. The results show that the proposed cycle with mass recovery produces as high of a COP as the COP that is produced by the conventional cascading cycle. However, it produces a lower SCP than that of the single-stage cycle.

  8. Microwave heating of arginine yields highly fluorescent nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Philippidis, Aggelos [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser (Greece); Stefanakis, Dimitrios [University of Crete, Department of Chemistry (Greece); Anglos, Demetrios, E-mail: anglos@iesl.forth.gr [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser (Greece); Ghanotakis, Demetrios, E-mail: ghanotakis@chemistry.uoc.gr [University of Crete, Department of Chemistry (Greece)

    2013-01-15

    Brightly fluorescent nanoparticles were produced via a single-step, single-precursor procedure based on microwave heating of an aqueous solution of the amino acid arginine. Key structural and optical properties of the resulting Arg nanoparticles, Arg-dots, are reported and discussed with emphasis on the pH dependence of their fluorescence emission. The surface of the Arg-dots was functionalised through coupling to folic acid, opening up ways for connecting fluorescent nanoparticles to cancer cells. The generality and versatility of the microwave heating procedure was further demonstrated by the synthesis of different types of carbon nanoparticles, such as CE-dots, that were produced by use of citric acid and ethanolamine as precursors and compared to the Arg-dots.

  9. Applications of High-Resolution Electrospray Ionization Mass Spectrometry to Measurements of Average Oxygen to Carbon Ratios in Secondary Organic Aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Bateman, Adam P.; Laskin, Julia; Laskin, Alexander; Nizkorodov, Sergey

    2012-07-02

    The applicability of high resolution electrospray ionization mass spectrometry (HR ESI-MS) to measurements of the average oxygen to carbon ratio (O/C) in organic aerosols was investigated. Solutions with known average O/C containing up to 10 standard compounds representative of secondary organic aerosol (SOA) were analyzed and corresponding electrospray ionization efficiencies were quantified. The assumption of equal ionization efficiency commonly used in estimating O/C ratios of organic aerosols was found to be reasonably accurate. We found that the accuracy of the measured O/C ratios increases by averaging the values obtained from both (+) and (-) modes. A correlation was found between the ratio of the ionization efficiencies in the positive and negative ESI modes with the octanol-water partition constant, and more importantly, with the compound's O/C. To demonstrate the utility of this correlation for estimating average O/C values of unknown mixtures, we analyzed the ESI (+) and ESI (-) data for SOA produced by oxidation of limonene and isoprene and compared to online O/C measurements using an aerosol mass spectrometer (AMS). This work demonstrates that the accuracy of the HR ESI-MS methods is comparable to that of the AMS, with the added benefit of molecular identification of the aerosol constituents.

  10. High average daily intake of PCDD/Fs and serum levels in residents living near a deserted factory producing pentachlorophenol (PCP) in Taiwan: Influence of contaminated fish consumption

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C.C. [Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, Tainan, Taiwan (China); Research Center of Environmental Trace Toxic Substances, Medical College, National Cheng Kung University, Tainan, Taiwan (China); Lin, W.T. [Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, Tainan, Taiwan (China); Liao, P.C. [Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, Tainan, Taiwan (China); Research Center of Environmental Trace Toxic Substances, Medical College, National Cheng Kung University, Tainan, Taiwan (China); Su, H.J. [Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, Tainan, Taiwan (China); Research Center of Environmental Trace Toxic Substances, Medical College, National Cheng Kung University, Tainan, Taiwan (China); Chen, H.L. [Department of Industrial Safety and Health, Hung Kuang University, Taichung, 34 Chung Chie Rd. Sha Lu, Taichung 433, Taiwan (China)]. E-mail: hsiulin@sunrise.hk.edu.tw

    2006-05-15

    An abandoned pentachlorophenol plant and nearby area in southern Taiwan was heavily contaminated by dioxins, impurities formed in the PCP production process. The investigation showed that the average serum PCDD/Fs of residents living nearby area (62.5 pg WHO-TEQ/g lipid) was higher than those living in the non-polluted area (22.5 and 18.2 pg WHO-TEQ/g lipid) (P < 0.05). In biota samples, average PCDD/F of milkfish in sea reservoir (28.3 pg WHO-TEQ/g) was higher than those in the nearby fish farm (0.15 pg WHO-TEQ/g), and Tilapia and shrimp showed the similar trend. The average daily PCDD/Fs intake of 38% participants was higher than 4 pg WHO-TEQ/kg/day suggested by the world health organization. Serum PCDD/F was positively associated with average daily intake (ADI) after adjustment for age, sex, BMI, and smoking status. In addition, a prospective cohort study is suggested to determine the long-term health effects on the people living near factory. - Inhabitants living near a deserted PCP factory are exposed to high PCDD/F levels.

  11. Heat Waves

    Science.gov (United States)

    Heat Waves Dangers we face during periods of very high temperatures include: Heat cramps: These are muscular pains and ... having trouble with the heat. If a heat wave is predicted or happening… - Slow down. Avoid strenuous ...

  12. Response of NSTX liquid lithium divertor to high heat loads

    Energy Technology Data Exchange (ETDEWEB)

    Abrams, T., E-mail: tabrams@pppl.gov [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Jaworski, M.A. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Kallman, J. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Kaita, R. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Foley, E.L. [Nova Photonics, Inc., Princeton, NJ 08543 (United States); Gray, T.K. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Kugel, H. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Levinton, F. [Nova Photonics, Inc., Princeton, NJ 08543 (United States); McLean, A.G. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Skinner, C.H. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States)

    2013-07-15

    Samples of the NSTX Liquid Lithium Divertor (LLD) with and without an evaporative Li coating were directly exposed to a neutral beam ex-situ at a power of ∼1.5 MW/m{sup 2} for 1–3 s. Measurements of front face and bulk sample temperature were obtained. Predictions of temperature evolution were derived from a 1D heat flux model. No macroscopic damage occurred when the “bare” sample was exposed to the beam but microscopic changes to the surface were observed. The Li-coated sample developed a lithium hydroxide (LiOH) coating, which did not change even when the front face temperature exceeded the pure Li melting point. These results are consistent with the lack of damage to the LLD surface and imply that heating alone may not expose pure liquid Li if the melting point of surface impurities is not exceeded. This suggests that flow and heat are needed for future PFCs requiring a liquid Li surface.

  13. Transient modeling of the thermohydraulic behavior of high temperature heat pipes for space reactor applications

    Science.gov (United States)

    Hall, Michael L.; Doster, Joseph M.

    1986-01-01

    Many proposed space reactor designs employ heat pipes as a means of conveying heat. Previous researchers have been concerned with steady state operation, but the transient operation is of interest in space reactor applications due to the necessity of remote startup and shutdown. A model is being developed to study the dynamic behavior of high temperature heat pipes during startup, shutdown and normal operation under space environments. Model development and preliminary results for a hypothetical design of the system are presented.

  14. Improving the Performance of a Semitransparent BIPV by Using High-Reflectivity Heat Insulation Film

    OpenAIRE

    Huei-Mei Liu; Chin-Huai Young; Der-Juinn Horng; Yih-Chearng Shiue; Shin-Ku Lee

    2016-01-01

    Currently, standard semitransparent photovoltaic (PV) modules can largely replace architectural glass installed in the windows, skylights, and facade of a building. Their main features are power generation and transparency, as well as possessing a heat insulating effect. Through heat insulation solar glass (HISG) encapsulation technology, this study improved the structure of a typical semitransparent PV module and explored the use of three types of high-reflectivity heat insulation films to f...

  15. Characteristic features of the operation of high-temperature heat pipes with a noncondesable gas

    Science.gov (United States)

    Tolubinskiy, V. I.; Shevchuk, Ye. N.

    1987-01-01

    The principal concepts related to the nature of the processes occurring in high-temperature heat pipes with a noncondensable gas are examined, and guidelines for the development of such heat pipes are presented. The discussion is illustrated by experimental results obtained for a horizontal sodium heat pipe (diameter, 18/1 mm; length, 710 mm). In particular, attention is given to the starting dynamics and mechanisms, the shape of the vapor-gas front, and the vapor-gas front velocity.

  16. Influence of Heat-radiating on Multi-photon Compton Scattering High-energy Electron

    Institute of Scientific and Technical Information of China (English)

    HAO Dong-shan; WANG Xin-min

    2007-01-01

    Using the model of the inverse Compton scattering between high-energy electrons and heat-radiation photons, the influence of heat-radiating photons on multi-photon Compton scattering high-energy electrons is studied . The results show that the energy loss, power loss, light resistance and light pressure of the high-energy electron formed by heat radiating are all proportional to the temperature T4 of the vacuum cavity of the electron,the Lorentz factor γ2 of the high-energy electrons, the scattering section of the electron and the number of photons acting at the same time with high-energy electrons. A good method for lessening the energy loss of the high-energy electron by using the one-photon Compton scattering between high-energy electrons and heat radiation photons is proposed.

  17. Development of a kilowatt-class, joule-level ultrafast laser for driving compact high average power coherent EUV/soft x-ray sources

    Science.gov (United States)

    Reagan, Brendan A.; Baumgarten, Cory M.; Pedicone, Michael A.; Bravo, Herman; Yin, Liang; Woolston, Mark; Wang, Hanchen; Menoni, Carmen S.; Rocca, Jorge J.

    2016-03-01

    Our recent progress in the development of high energy / high average power, chirped pulse amplification laser systems based on diode-pumped, cryogenically-cooled Yb:YAG amplifiers is discussed, including the demonstration of a laser that produces 1 Joule, sub-10 picosecond duration, λ = 1.03μm pulses at 500 Hz repetition rate. This compact, all-diodepumped laser combines a mode-locked Yb:KYW oscillator and a water-cooled Yb:YAG preamplifer with two cryogenic power amplification stages to produce 1.5 Joule pulses with high beam quality which are subsequently compressed. This laser system occupies an optical table area of less than 1.5x3m2. This laser was employed to pump plasma-based soft x-ray lasers at λ = 10-20nm at repetition rates >=100 Hz. To accomplish this, temporally-shaped pulses were focused at grazing incidence into a high aspect ratio line focus using cylindrical optics on a high shot capacity rotating metal target. This results in an elongated plasma amplifier that produces microjoule pulses at several narrow-linewidth EUV wavelengths between λ = 109Å and 189Å. The resulting fraction of a milliwatt average powers are the highest reported to date for a compact, coherent source operating at these wavelengths, to the best of our knowledge.

  18. Preliminary study on heat load using calorimetric measurement during long-pulse high-performance discharges on EAST

    Science.gov (United States)

    Liu, Y. K.; Hamada, N.; Hanada, K.; Gao, X.; Liu, H. Q.; Yu, Y. W.; Qian, J. P.; Yang, L.; Xu, T. J.; Jie, Y. X.; Yao, Y.; Wang, S. S.; Xu, J. C.; Yang, Z. D.; Li, G. S.; EAST Team

    2017-04-01

    Experimental Advanced Superconducting Tokamak (EAST) aims to demonstrate steady-state advanced high-performance H-mode plasmas with an ITER-like configuration, plasma control and heating schemes. The plasma-facing components in EAST are actively cooled, providing good conditions for researching long-pulse and high-energy discharges. A long-pulse high-performance plasma discharge (#59892 discharge) of up to 103 s with a core electron temperature of up to 4.5 keV was sustained with an injected energy exceeding 0.22 GJ in the 2015–2016 experimental campaign. A calorimetric measurement utilizing the temperature increment of cooling water is carried out to calculate the heat load on the strike point region of the lower divertor during long-pulse discharges in EAST. For the long-pulse and high-energy discharges, the comparison of the measurement results for the heat load measured by divertor Langmuir probes and the calorimetry diagnostic indicates that most of the heat load is delivered to the divertor panels as plasma, not radiation, and charge exchange neutrals. The ratio of the heat load on the strike point region of the lower divertor to the total injected energy is on average 42.5% per discharge with the lower single null divertor configuration. If the radiated energy loss measured by the fast bolometer diagnostic is taken into consideration, the ratio is found to be 61.6%. The experimental results and the analysis of the physics involved in these discharges are reported and discussed.

  19. GRCop-84: A High Temperature Copper-based Alloy For High Heat Flux Applications

    Science.gov (United States)

    Ellis, David L.

    2005-01-01

    While designed for rocket engine main combustion chamber liners, GRCop-84 (Cu-8 at.% Cr-4 at.% Nb) offers potential for high heat flux applications in industrial applications requiring a temperature capability up to approximately 700 C (1292 F). GRCop-84 is a copper-based alloy with excellent elevated temperature strength, good creep resistance, long LCF lives and enhanced oxidation resistance. It also has a lower thermal expansion than copper and many other low alloy copper-based alloys. GRCop-84 can be manufactured into a variety of shapes such as tubing, bar, plate and sheet using standard production techniques and requires no special production techniques. GRCop-84 forms well, so conventional fabrication methods including stamping and bending can be used. GRCop-84 has demonstrated an ability to be friction stir welded, brazed, inertia welded, diffusion bonded and electron beam welded for joining to itself and other materials. Potential applications include plastic injection molds, resistance welding electrodes and holders, permanent metal casting molds, vacuum plasma spray nozzles and high temperature heat exchanger applications.

  20. High current multicharged metal ion source using high power gyrotron heating of vacuum arc plasma.

    Science.gov (United States)

    Vodopyanov, A V; Golubev, S V; Khizhnyak, V I; Mansfeld, D A; Nikolaev, A G; Oks, E M; Savkin, K P; Vizir, A V; Yushkov, G Yu

    2008-02-01

    A high current, multi charged, metal ion source using electron heating of vacuum arc plasma by high power gyrotron radiation has been developed. The plasma is confined in a simple mirror trap with peak magnetic field in the plug up to 2.5 T, mirror ratio of 3-5, and length variable from 15 to 20 cm. Plasma formed by a cathodic vacuum arc is injected into the trap either (i) axially using a compact vacuum arc plasma gun located on axis outside the mirror trap region or (ii) radially using four plasma guns surrounding the trap at midplane. Microwave heating of the mirror-confined, vacuum arc plasma is accomplished by gyrotron microwave radiation of frequency 75 GHz, power up to 200 kW, and pulse duration up to 150 micros, leading to additional stripping of metal ions by electron impact. Pulsed beams of platinum ions with charge state up to 10+, a mean charge state over 6+, and total (all charge states) beam current of a few hundred milliamperes have been formed.

  1. Experimental analysis on performance of high temperature heat pump and desiccant wheel system

    DEFF Research Database (Denmark)

    Sheng, Ying; Zhang, Yufeng; Deng, Na

    2013-01-01

    In order to solve the problem of high energy consumption for regeneration of desiccant wheel in the rotary desiccant system, high temperature heat pump and desiccant wheel (HTHP&DW) system and corresponding air conditioning unit is built and tested in the extensive thermal hygrometric environment....... When the mixture refrigerant BY-3 is involved in the air source heat pump, the supply air temperatures are in the range as expected except that when in the extreme hot environment (above 36°C), dehumidification capability are satisfied and the regeneration temperatures can satisfy the regeneration...... requirement of desiccant without additional heat. It is also found that outdoor air temperature, humidity ratio and regeneration air flow rate have great impact on the performance of heat pump based on the coefficient of performance (COP) evaluated. COP is not quite high, as the maximum value is 2.26 for heat...

  2. Synthesis of Polyheteroarylenes for Highly Heat-Resistant Materials,

    Science.gov (United States)

    1984-04-04

    conditions selected. Thus, fiber glass plastics based on the fabric TS-8/3-2500 and polymer POD-2 retained their ultimate strength during bending (d6S" at...oxolone, which is in the class of polybenzoxazoles . The most thermostable struc- .ure of oxolone is formed not in one stage, as that in POD-2, but in two...during the first stage, which transforms into polybenzoxazole during the second stage as a result of heat treatment under vacuum or in an inert medium

  3. CONJUGATE MODEL FOR HEAT AND MASS TRANSFER OF POROUS WALL IN THE HIGH TEMPERATURE GAS FLOW

    Institute of Scientific and Technical Information of China (English)

    A.F. Polyakov; D.L.Reviznikov; 沈青; 魏叔如

    2001-01-01

    Heat and mass transfer of a porous permeable wall in a high temperature gas dynamical flow is considered. Numerical simulation is conducted on the ground of the conjugate mathematical model which includes filtration and heat transfer equations in a porous body and boundary layer equations on its surface. Such an approach enables one to take into account complex interaction between heat and mass transfer in the gasdynamical flow and in the structure subjected to this flow.The main attention is given to the impact of the intraporous heat transfer intensity on the transpiration cooling efficiency.

  4. Liquid fuel film ignition delay times on the substrate heated up to high temperatures

    Directory of Open Access Journals (Sweden)

    Antonov D.V.

    2015-01-01

    Full Text Available Heat and mass transfer processes under the conditions of unsteady evaporation and boiling of the liquid fuel film in coordination with the substrate heated up to high temperatures were investigated. The film thickness values and the substrate temperature (whereby the ignition conditions are not implemented were determined. The film thickness values and the substrate temperature (whereby as low as practicable ignition delay times are provided were found. The differences of liquid fuel film ignition condition under the local heating and the interoperating with the massive heating source were analyzed.

  5. Study on Heat Dissipater for High-Power Thyristors in Explosion-Proof Shell

    Institute of Scientific and Technical Information of China (English)

    SONG Zheng-chang; LI Chuan-tong

    2003-01-01

    A new type water-cooled heat dissipater for multiple high-power thyristors in explosion-proof shell used in coal mine was designed, and then, the numerical computation of the three-dimensional steady-state temperature distributions under different working conditions for cooling core was conducted in order to understand in detail the heat transfer performance. Based on the computation results, the temperature differences and the maximum heat transfer rates were given. These results of the study on the heat dissipater lay a basis for optimising its structure design and guiding its operation.

  6. From urban to national heat island: The effect of anthropogenic heat output on climate change in high population industrial countries

    Science.gov (United States)

    Murray, John; Heggie, Douglas

    2016-06-01

    The project presented here sought to determine whether changes in anthropogenic thermal emission can have a measurable effect on temperature at the national level, taking Japan and Great Britain as type examples. Using energy consumption as a proxy for thermal emission, strong correlations (mean r2 = 0.90 and 0.89, respectively) are found between national equivalent heat output (HO) and temperature above background levels Δt averaged over 5- to 8-yr periods between 1965 and 2013, as opposed to weaker correlations for CMIP5 model temperatures above background levels Δmt (mean r2 = 0.52 and 0.10). It is clear that the fluctuations in Δt are better explained by energy consumption than by present climate models, and that energy consumption can contribute to climate change at the national level on these timescales.

  7. On the development of high temperature ammonia-water hybrid absorption-compression heat pumps

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Markussen, Wiebke Brix; Reinholdt, Lars

    2015-01-01

    Ammonia-water hybrid absorption-compression heat pumps (HACHP) are a promising technology for development of ecient high temperature industrial heat pumps. Using 28 bar components HACHPs up to 100 °C are commercially available. Components developed for 50 bar and 140 bar show that these pressure...

  8. HEAT TRANSFER EVALUATION OF HFC-236EA WITH HIGH PERFORMANCE ENHANCED TUBES IN CONDENSATION AND EVAPORATION

    Science.gov (United States)

    The report gives results of an evaluation of the heat transfer performance of pure hydrofluorocarbon (HFC)-236ea for high performance enhanced tubes which had not been previously used in Navy shipboard chillers. Shell-side heat transfer coefficient data are presented for condensa...

  9. High pressure versus heat treatments for pasteurisation and sterilisation of model emulsions

    NARCIS (Netherlands)

    Ven, van der C.; Courvoisier, C.; Matser, A.M.

    2007-01-01

    Heat treatments can have considerable influence on the droplet size distribution of oil-in-water emulsions. In the present study, high-pressure (HP) pasteurisation and sterilisation were evaluated as alternatives for heat preservation of emulsions. HP conditions used were 600 MPa, 5 min, room temper

  10. Optimization of a thermoelectric generator subsystem for high temperature PEM fuel cell exhaust heat recovery

    DEFF Research Database (Denmark)

    Gao, Xin; Andreasen, Søren Juhl; Kær, Søren Knudsen

    2014-01-01

    In previous work, a thermoelectric (TE) exhaust heat recovery subsystem for a high temperature polymer electrolyte membrane (HT-PEM) fuel cell stack was developed and modeled. Numerical simulations were conducted and have identified an optimized subsystem configuration and 4 types of compact heat...

  11. Using a Potassium Acetate Solution for Cooling High Pressure Hydrogen in a Prototype Heat Exchanger

    DEFF Research Database (Denmark)

    Rothuizen, Erasmus Damgaard; Abel, M.; Rokni, Masoud;

    2011-01-01

    is to be delivered at high pressure a heat exchanger was designed and constructed. The paper presents a detailed study of construction of the heat exchanger which has been tested and compared to theory to predict and verify its performance. The method presented by Nellis and Klein for laminar flow in annulus tubes...

  12. Using a Potassium Acetate Solution for Cooling High Pressure Hydrogen in a Prototype Heat Exchanger

    DEFF Research Database (Denmark)

    Rothuizen, Erasmus Damgaard; Abel, M.; Rokni, Masoud

    2011-01-01

    is to be delivered at high pressure a heat exchanger was designed and constructed. The paper presents a detailed study of construction of the heat exchanger which has been tested and compared to theory to predict and verify its performance. The method presented by Nellis and Klein for laminar flow in annulus tubes...

  13. High-resolution hot-film measurement of surface heat flux to an impinging jet

    Science.gov (United States)

    O'Donovan, T. S.; Persoons, T.; Murray, D. B.

    2011-10-01

    To investigate the complex coupling between surface heat transfer and local fluid velocity in convective heat transfer, advanced techniques are required to measure the surface heat flux at high spatial and temporal resolution. Several established flow velocity techniques such as laser Doppler anemometry, particle image velocimetry and hot wire anemometry can measure fluid velocities at high spatial resolution (µm) and have a high-frequency response (up to 100 kHz) characteristic. Equivalent advanced surface heat transfer measurement techniques, however, are not available; even the latest advances in high speed thermal imaging do not offer equivalent data capture rates. The current research presents a method of measuring point surface heat flux with a hot film that is flush mounted on a heated flat surface. The film works in conjunction with a constant temperature anemometer which has a bandwidth of 100 kHz. The bandwidth of this technique therefore is likely to be in excess of more established surface heat flux measurement techniques. Although the frequency response of the sensor is not reported here, it is expected to be significantly less than 100 kHz due to its physical size and capacitance. To demonstrate the efficacy of the technique, a cooling impinging air jet is directed at the heated surface, and the power required to maintain the hot-film temperature is related to the local heat flux to the fluid air flow. The technique is validated experimentally using a more established surface heat flux measurement technique. The thermal performance of the sensor is also investigated numerically. It has been shown that, with some limitations, the measurement technique accurately measures the surface heat transfer to an impinging air jet with improved spatial resolution for a wide range of experimental parameters.

  14. Heat accumulation during high repetition rate ultrafast laser interaction: Waveguide writing in borosilicate glass

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haibin; Eaton, Shane M; Li, Jianzhao; Herman, Peter R [The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Toronto, ON, M5S 3G4 (Canada)

    2007-04-15

    During high repetition rate (>200 kHz) ultrafast laser waveguide writing, visible heat modified zones surrounding the formed waveguide occur as a result of heat accumulation. The radii of the heat-modified zones increase with the laser net fluence, and were found to correlate with the formation of low-loss and cylindrically symmetric optical waveguides. A numerical thermal model based on the finite difference method is applied here to account for cumulative heating and diffusion effects. The model successfully shows that heat propagation and accumulation accurately predict the radius of the 'heat modified' zones observed in borosilicate glass waveguides formed across a wide range of laser exposure conditions. Such modelling promises better control of thermal effects for optimizing the fabrication and performance of three-dimensional optical devices in transparent materials.

  15. High temperature superconducting current lead test facility with heat pipe intercepts

    Energy Technology Data Exchange (ETDEWEB)

    Blumenfeld, P.E.; Prenger, C.; Roth, E.W.; Stewart, J.A.

    1998-12-31

    A high temperature superconducting (HTS) current lead test facility using heat pipe thermal intercepts is under development at the Superconducting Technology Center at Los Alamos National Laboratory. The facility can be configured for tests at currents up to 1,000 A. Mechanical cryocoolers provide refrigeration to the leads. Electrical isolation is maintained by intercepting thermal energy from the leads through cryogenic heat pipes. HST lead warm end temperature is variable from 65 K to over 90 K by controlling heat pipe evaporator temperature. Cold end temperature is variable up to 30 K. Performance predictions in terms of heat pipe evaporator temperature as a function of lead current are presented for the initial facility configuration, which supports testing up to 200 A. Measurements are to include temperature and voltage gradient in the conventional and HTS lead sections, temperature and heat transfer rate in the heat pipes. as well as optimum and off-optimum performance of the conventional lead sections.

  16. High Temperature Heat Pump Integration using Zeotropic Working Fluids for Spray Drying Facilities

    DEFF Research Database (Denmark)

    Zühlsdorf, Benjamin; Bühler, Fabian; Mancini, Roberta

    2017-01-01

    This paper presents an analysis of high temperature heat pumps in the industrial sector and demonstrates the approach of using zeotropic mixtures to enhance the overall efficiency. Many energy intensive processes in industry, such as drying processes, require heat at a temperature above 100 °C...... and show a large potential to reuse the excess heat from exhaust gases. This study analyses a heat pump application with an improved integration by choosing the working fluid as a mixture in such a way, that the temperature glide during evaporation and condensation matches the temperature glide of the heat...... that the utilization of mixtures allows a heat pump application to preheat the drying air to 120 °C with a COP of 3.04 and a NPV of 0.997 Mio. €, which could reduce the natural gas consumption by 36 %....

  17. High efficient ammonia heat pump system for industrial process water using the ISEC concept. Part 1

    DEFF Research Database (Denmark)

    Rothuizen, Erasmus Damgaard; Madsen, C.; Elmegaard, Brian

    2014-01-01

    The purpose of the Isolated System Energy Charging (ISEC) is to provide a high-efficient ammonia heat pump system for hot water production. The ISEC concept uses two storage tanks for the water, one discharged and one charged. The charged tank is used for the industrial process while the discharged...... to investigate the performance of the ISEC system. The ISEC concept approaches the efficiency of a number of heat pumps in series and the COP of the system may reach 6.8, which is up to 25 % higher than a conventional heat pump heating water in one step....... tank, is charging. Charging is done by circulating the water in the tank through the condenser several times and thereby gradually heats the water. This result in a lower condensing temperature than if the water was heated in one step. A dynamic model of the system, implemented in Dymola, is used...

  18. High strength microstructural forms developed in titanium alloys by rapid heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Ivasishin, O.M. [Institute of Metal Physics, Kiev (Ukraine)

    2001-09-01

    It is shown that rapid heat treatment of alpha+beta and beta titanium alloys, which includes rapid heating of alloys with initial equiaxed microstructure into single-phase beta field is able to produce microstructural forms in which high strength can be well balanced with other mechanical properties. Main advantage of rapid heating approach comes from the possibility to extend the level of ''useful'' strength. Desirably high strength is provided by intragranular morphology and microchemistry while beta-grain refinement permits a reliability of such high strength conditions. (orig.)

  19. Operational demonstration of a field of high performance flat plate collectors with isothermal heat transport

    Science.gov (United States)

    Merges, V.; Klippel, E.

    1983-12-01

    A solar plant with 21 sq m of highly efficient flat plate collectors and which requires no electricity is described. Heat transport is provided by saturated steam that condenses in a four cubic meter storage tank. The operation temperature is set by the buffer gas pressure between 100 and 140 C, and an absorption chiller is simulated as a heat consumer. The solar collectors were observed to exhibit high performance. Heat transport and temperature control offered high reliability and the thermal stratification in the tank was satisfactory. The positive result permits the design and construction of larger solar plants following the same technical principles.

  20. High-Speed Visual Analysis of Fluid Flow and Heat Transfer in Oscillating Heat Pipes with Different Diameters

    Directory of Open Access Journals (Sweden)

    Xiangdong Liu

    2016-10-01

    Full Text Available The oscillating heat pipe (OHP is a new member in the family of heat pipes, and it has great potential applications in energy conservation. However, the fluid flow and heat transfer in the OHP as well as the fundamental effects of inner diameter on them have not been fully understood, which are essential to the design and optimization of the OHP in real applications. Therefore, by combining the high-speed visualization method and infrared thermal imaging technique, the fluid flow and thermal performance in the OHPs with inner diameters of 1, 2 and 3 mm are presented and analyzed. The results indicate that three fluid flow motions, including small oscillation, bulk oscillation and circulation, coexist or, respectively, exist alone with the increasing heating load under different inner diameters, with three flow patterns occurring in the OHPs, viz. bubbly flow, slug flow and annular flow. These fluid flow motions are closely correlated with the heat and mass transfer performance in the OHPs, which can be reflected by the characteristics of infrared thermal images of condensers. The decrease in the inner diameter increases the frictional flow resistance and capillary instability while restricting the nucleate boiling in OHPs, which leads to a smaller proportion of bubbly flow, a larger proportion of short slug flow, a poorer thermal performance, and easier dry-out of working fluid. In addition, when compared with the 2 mm OHP, the increasing role of gravity induces the thermosyphon effect and weakens the ‘bubble pumping’ action, which results in a little smaller and bigger thermal resistances of 3 mm OHP under small and bulk oscillation of working fluid, respectively.

  1. R&D on Resistive Heat Exchangers for HTS High Rated Current Leads%R&D on Resistive Heat Exchangers for HTS High Rated Current Leads

    Institute of Scientific and Technical Information of China (English)

    毕延芳

    2011-01-01

    The HTS current leads of superconducting magnets for large scale fusion devices and high energy particle colliders can reduce the power consumption for cooling by 2/3 compared with conventional leads. The resistive sections of high-rated current leads are usually made of a heat exchanger cooled by gas flow. The supply of the cooling mass flow incurs more than 90% of the cooling cost for the HTS leads. The mass flow rate requirement depends not only on the length and material of the resistive heat exchanger, but also on the heat transfer coefficient and HEX surface, the joint resistance at the cold end of a sheet-stack HEX with a larger specific presented in the paper. The test results of efficiency can be achieved. and its cooling approach. The design and operation surface and a much smaller hydraulic diameter are an HTS lead optimized for 8 kA show that a 98.4%

  2. Boiling Heat-Transfer Processes and Their Application in the Cooling of High Heat Flux Devices

    Science.gov (United States)

    1993-06-01

    large for very smooth surfaces or highly wettable fluids (e.g., refrigerants or liquid metals) which can lead to explosive boiling (known as bumping) that...of the high wettability of liquid metals, high superheats are normally required to initiate boiling, in some cases having an explosive transition that...About the same time, Staub and Walmet (Ref. 175) identified the two regions before and after the point of significant vapor generation (SNVG) where the

  3. Cutting heat dissipation in high-speed machining of carbon steel based on the calorimetric method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The cutting heat dissipation in chips,workpiece,tool and surroundings during the high-speed machining of carbon steel is quantitatively investigated based on the calorimetric method.Water is used as the medium to absorb the cutting heat;a self-designed container suitable for the high-speed lathe is used to collect the chips,and two other containers are adopted to absorb the cutting heat dissipated in the workpiece and tool,respectively.The temperature variations of the water,chips,workpiece,tool and surroundings during the closed high-speed machining are then measured.Thus,the cutting heat dissipated in each component of the cutting system,total cutting heat and heat flux are calculated.Moreover,the power resulting from the main cutting force is obtained according to the measured cutting force and predetermined cutting speed.The accuracy of cutting heat measurement by the calorimetric method is finally evaluated by comparing the total cutting heat flux with the power resulting from the main cutting force.

  4. High temperature heat pumps for industrial cooling; Hoejtemperatur varmepumper til industriel koeling

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, Lars; Nielsen, Jacob [Advansor A/S, Aarhus (Denmark); Kronborg, H. [Cronborg, Holstebro (Denmark); Skouenborg, K. [Jensens Koekken, Struer (Denmark)

    2013-03-15

    This report deals with theoretical analysis of various types of integration of heat pumps in the industry, as well as a demonstration plant that serves the project's practical execution. The report describes the system integration between heat pumps and existing industrial cooling systems. Ammonia plants in industry are estimated to have an allocation of 85%, which is why only an analysis of this type of installation as surplus heat supplier is included in this report. In contrast, heat pumps with both CO{sub 2} and Isobutane as the refrigerant are analysed, since these are the interesting coolants for generating high temperature heat. It can be seen through the project that the combination of heat pump with existing cooling installations may produce favorable situations where the efficiency of the heat pump is extremely high while at the same time electricity and water consumption for the cooling system is reduced. The analysis reflects that CO{sub 2} is preferred over Isobutane in the cases where a high level of temperature boost is desired, whereas Isobutane is preferable at low level of temperature boost. In the demonstration project, the report shows that the heat pump alone has a COP of 4.1, while the achieved COP is 5.5 when by considering the system as a whole. In addition to increased performance the solution profits by having a reduction in CO{sub 2} emissions of 81 tons/year and a saving of 470,000 DKK/year. (LN)

  5. Recrystallization and grain growth behavior of rolled tungsten under VDE-like short pulse high heat flux loads

    Science.gov (United States)

    Yuan, Y.; Greuner, H.; Böswirth, B.; Krieger, K.; Luo, G.-N.; Xu, H. Y.; Fu, B. Q.; Li, M.; Liu, W.

    2013-02-01

    Short pulse heat loads expected for vertical displacement events (VDEs) in ITER were applied in the high heat flux (HHF) test facility GLADIS at IPP-Garching onto samples of rolled W. Pulsed neutral beams with the central heat flux of 23 MW/m2 were applied for 0.5, 1.0 and 1.5 s, respectively. Rapid recrystallization of the adiabatically loaded 3 mm thick samples was observed when the pulse duration was up to 1.0 s. Grains grew markedly following recrystallization with increasing pulse length. The recrystallization temperature and temperature dependence of the recrystallized grain size were also investigated. The results showed that the recrystallization temperature of the W grade was around 2480 °C under the applied heat loading condition, which was nearly 1150 °C higher than the conventional recrystallization temperature, and the grains were much finer. A linear relationship between the logarithm of average grain size (ln d) and the inverse of maximum surface temperature (1/Tmax) was found and accordingly the activation energy for grain growth in temperature evolution up to Tmax in 1.5 s of the short pulse HHF load was deduced to be 4.1 eV. This provided an effective clue to predict the structure evolution under short pulse HHF loads.

  6. Turbulent fluxes of momentum and heat over land in the High-Arctic summer: the influence of observation techniques

    Directory of Open Access Journals (Sweden)

    Anna Sjöblom

    2014-06-01

    Full Text Available Different observation techniques for atmospheric turbulent fluxes of momentum and sensible heat were tested in a High-Arctic valley in Svalbard during two consecutive summers (June–August in 2010 and 2011. The gradient method (GM and the bulk method (BM have been compared to the more direct eddy covariance method (ECM in order to evaluate if relatively robust and cheap instrumentation with low power consumption can be used as a means to increase the number of observations, especially at remote locations where instruments need to be left unattended for extended periods. Such campaigns increase knowledge about the snow-free surface exchange processes, an area which is relatively little investigated compared to snow-covered ground. The GM agreed closely to the ECM, especially for momentum flux where the two methods agree within 5%. For sensible heat flux, the GM produces, on average, approximately 40% lower values for unstable stratification and 67% lower for stable stratification. However, this corresponds to only 20 and 12 W m−2, respectively. The BM, however, shows a greater scatter and larger differences for both parameters. In addition to testing these methods, radiation properties were measured and the surface albedo was found to increase through the summer, from approximately 0.1 to 0.2. The surface energy budget shows that the sensible heat flux is usually directed upwards for the whole summer, while the latent heat flux is upwards in June, but becomes downward in July and August.

  7. Dynamo: a flexible, user-friendly development tool for subtomogram averaging of cryo-EM data in high-performance computing environments.

    Science.gov (United States)

    Castaño-Díez, Daniel; Kudryashev, Mikhail; Arheit, Marcel; Stahlberg, Henning

    2012-05-01

    Dynamo is a new software package for subtomogram averaging of cryo Electron Tomography (cryo-ET) data with three main goals: first, Dynamo allows user-transparent adaptation to a variety of high-performance computing platforms such as GPUs or CPU clusters. Second, Dynamo implements user-friendliness through GUI interfaces and scripting resources. Third, Dynamo offers user-flexibility through a plugin API. Besides the alignment and averaging procedures, Dynamo includes native tools for visualization and analysis of results and data, as well as support for third party visualization software, such as Chimera UCSF or EMAN2. As a demonstration of these functionalities, we studied bacterial flagellar motors and showed automatically detected classes with absent and present C-rings. Subtomogram averaging is a common task in current cryo-ET pipelines, which requires extensive computational resources and follows a well-established workflow. However, due to the data diversity, many existing packages offer slight variations of the same algorithm to improve results. One of the main purposes behind Dynamo is to provide explicit tools to allow the user the insertion of custom designed procedures - or plugins - to replace or complement the native algorithms in the different steps of the processing pipeline for subtomogram averaging without the burden of handling parallelization. Custom scripts that implement new approaches devised by the user are integrated into the Dynamo data management system, so that they can be controlled by the GUI or the scripting capacities. Dynamo executables do not require licenses for third party commercial software. Sources, executables and documentation are freely distributed on http://www.dynamo-em.org.

  8. Signal-to-noise ratio improvements in laser flow diagnostics using time-resolved image averaging and high dynamic range imaging

    Science.gov (United States)

    Giassi, Davide; Long, Marshall B.

    2016-08-01

    Two alternative image readout approaches are demonstrated to improve the signal-to-noise ratio (SNR) in temporally resolved laser-based imaging experiments of turbulent phenomena. The first method exploits the temporal decay characteristics of the phosphor screens of image intensifiers when coupled to an interline-transfer CCD camera operated in double-frame mode. Specifically, the light emitted by the phosphor screen, which has a finite decay constant, is equally distributed and recorded over the two sequential frames of the detector so that an averaged image can be reconstructed. The characterization of both detector and image intensifier showed that the technique preserves the correct quantitative information, and its applicability to reactive flows was verified using planar Rayleigh scattering and tested with the acquisition of images of both steady and turbulent partially premixed methane/air flames. The comparison between conventional Rayleigh results and the averaged ones showed that the SNR of the averaged image is higher than the conventional one; with the setup used in this work, the gain in SNR was seen to approach 30 %, for both the steady and turbulent cases. The second technique uses the two-frame readout of an interline-transfer CCD to increase the image SNR based on high dynamic range imaging, and it was tested in an unsteady non-reactive flow of Freon-12 injected in air. The result showed a 15 % increase in the SNR of the low-pixel-count regions of an image, when compared to the pixels of a conventionally averaged one.

  9. Heat treated 9 Cr-1 Mo steel material for high temperature application

    Science.gov (United States)

    Jablonski, Paul D.; Alman, David; Dogan, Omer; Holcomb, Gordon; Cowen, Christopher

    2012-08-21

    The invention relates to a composition and heat treatment for a high-temperature, titanium alloyed, 9 Cr-1 Mo steel exhibiting improved creep strength and oxidation resistance at service temperatures up to 650.degree. C. The novel combination of composition and heat treatment produces a heat treated material containing both large primary titanium carbides and small secondary titanium carbides. The primary titanium carbides contribute to creep strength while the secondary titanium carbides act to maintain a higher level of chromium in the finished steel for increased oxidation resistance, and strengthen the steel by impeding the movement of dislocations through the crystal structure. The heat treated material provides improved performance at comparable cost to commonly used high-temperature steels such as ASTM P91 and ASTM P92, and requires heat treatment consisting solely of austenization, rapid cooling, tempering, and final cooling, avoiding the need for any hot-working in the austenite temperature range.

  10. On the heat capacity of liquids at high temperatures

    CERN Document Server

    Stishov, S M

    2016-01-01

    Making use of a simple approximation for the evolution of the radial distribution function, we calculate the temperature dependence of the heat capacity $C_v$ of Ar at constant density. $C_v$ decreases with temperature roughly according to the law $\\sim T^{-1/4}$, slowly approaching the hard sphere asymptotic value $C_v=\\frac{3}{2}R$. However, the asymptotic value of $C_v$ is not reachable at reasonable temperatures , but stays close to 1.7--1.8 $R$ over a wide range of temperatures after passing a " magic " $2R$ value at about 2000 K. Nevertheless these values has nothing to do with loss of vibrational degrees of freedom, but arises as a result of a temperature variation of the collision diameter $\\sigma$. \\end{abstract}

  11. Computer simulation of metal wire explosion under high rate heating

    Science.gov (United States)

    Zolnikov, K. P.; Kryzhevich, D. S.; Korchuganov, A. V.

    2017-05-01

    Synchronous electric explosion of metal wires and synthesis of bicomponent nanoparticles were investigated on the base of molecular dynamics method. Copper and nickel nanosized crystallites of cylindrical shape were chosen as conductors for explosion. The embedded atom approximation was used for calculation of the interatomic interactions. The agglomeration process after explosion metal wires was the main mechanism for particle synthesis. The distribution of chemical elements was non-uniform over the cross section of the bicomponent particles. The copper concentration in the surface region was higher than in the bulk of the synthesized particle. By varying the loading parameters (heating temperature, the distance between the wires) one can control the size and internal structure of the synthesized bicomponent nanoparticles. The obtained results showed that the method of molecular dynamics can be effectively used to determine the optimal technological mode of nanoparticle synthesis on the base of electric explosion of metal wires.

  12. High-power and steady-state operation of ICRF heating in the large helical device

    Energy Technology Data Exchange (ETDEWEB)

    Mutoh, T., E-mail: mutoh@nifs.ac.jp; Seki, T.; Saito, K.; Kasahara, H.; Seki, R.; Kamio, S.; Kumazawa, R.; Kubo, S.; Shimozuma, T.; Yoshimura, Y.; Igami, H.; Takahashi, H.; Ii, T.; Makino, R.; Nagaoka, K.; Nomura, G. [National Institute for Fusion Science, 322-6, Oroshi-cho, Toki, Gifu, 509-5292 (Japan); Shinya, T. [The University of Tokyo, Kashiwa 2777-8561 (Japan)

    2015-12-10

    Recent progress in an ion cyclotron range of frequencies (ICRF) heating system and experiment results in a Large Helical Device (LHD) are reported. Three kinds of ICRF antenna pairs were installed in the LHD, and the operation power regimes were extended up to 4.5 MW; also, the steady-state operation was extended for more than 45 min in LHD at a MW power level. We studied ICRF heating physics in heliotron configuration using a Hand Shake type (HAS) antenna, Field Aligned Impedance Transforming (FAIT) antenna, and Poloidal Array (PA) antenna, and established the optimum minority-ion heating scenario in an LHD. The FAIT antenna having a novel impedance transformer inside the vacuum chamber could reduce the VSWR and successfully injected a higher power to plasma. We tested the PA antennas completely removing the Faraday-shield pipes to avoid breakdown and to increase the plasma coupling. The heating performance was almost the same as other antennas; however, the heating efficiency was degraded when the gap between the antenna and plasma surface was large. Using these three kinds of antennas, ICRF heating could contribute to raising the plasma beta with the second- and third-harmonic cyclotron heating mode, and also to raising the ion temperature as discharge cleaning tools. In 2014, steady-state operation plasma with a line-averaged electron density of 1.2 × 10{sup 19} m{sup −3}, ion and electron temperature of 2 keV, and plasma sustainment time of 48 min was achieved with ICH and ECH heating power of 1.2 MW for majority helium with minority hydrogen. In 2015, the higher-power steady-state operation with a heating power of up to 3 MW was tested with higher density of 3 × 10{sup 19} m{sup −3}.

  13. Fatty acids composition as a means to estimate the high heating value (HHV) of vegetable oils and biodiesel fuels

    Energy Technology Data Exchange (ETDEWEB)

    Fassinou, Wanignon Ferdinand; Koua, Kamenan Blaise; Toure, Siaka [Laboratoire d' Energie Solaire, UFR-SSMT, Universite de Cocody (Cote d' Ivoire), 22BP582 Abidjan 22 (Ivory Coast); Sako, Aboubakar; Fofana, Alhassane [Laboratoire de Physique de l' Atmosphere et de Mecanique des Fluides, UFR-SSMT, Universite de Cocody (Cote d' Ivoire), 22BP582 Abidjan 22 (Ivory Coast)

    2010-12-15

    High heating value (HHV) is an important property which characterises the energy content of a fuel such as solid, liquid and gaseous fuels. The previous assertion is particularly important for vegetable oils and biodiesels fuels which are expected to replace fossil oils. Estimation of the HHV of vegetable oils and biodiesels by using their fatty acid composition is the aim of this paper. The comparison between the HHVs predicted by the method and those obtained experimentally gives an average bias error of -0.84% and an average absolute error of 1.71%. These values show the utility, the validity and the applicability of the method to vegetable oils and their derivatives. (author)

  14. Effects of Hot Streak Shape on Rotor Heating in a High-Subsonic Single-Stage Turbine

    Science.gov (United States)

    Dorney, Daniel J.; Gundy-Burlet, Karen L.; Norvig, Peter (Technical Monitor)

    1999-01-01

    Experimental data have shown that combustor temperature non-uniformities can lead to the excessive heating of first-stage rotor blades in turbines. This heating of the rotor blades can lead to thermal fatigue and degrade turbine performance. The results of recent studies have shown that variations in the circumferential location (clocking) of the hot streak relative to the first-stage vane airfoils can be used to minimize the adverse effects of the hot streak. The effects of the hot streak/airfoil count ratio on the heating patterns of turbine airfoils have also been evaluated. In the present investigation, three-dimensional unsteady Navier-Stokes simulations have been performed for a single-stage high-pressure turbine operating in high subsonic flow. In addition to a simulation of the baseline turbine, simulations have been performed for circular and elliptical hot streaks of varying sizes in an effort to represent different combustor designs. The predicted results for the baseline simulation show good agreement with the available experimental data. The results of the hot streak simulations indicate: that a) elliptical hot streaks mix more rapidly than circular hot streaks, b) for small hot streak surface area the average rotor temperature is not a strong function of hot streak temperature ratio or shape, and c) hot streaks with larger surface area interact with the secondary flows at the rotor hub endwall, generating an additional high temperature region.

  15. Demonstration of a Low-Lift Heat Pump for High-Power Spacecraft Thermal Control

    Science.gov (United States)

    Grzyll, Lawrence R.

    2006-01-01

    This paper describes the development and demonstration of a prototype low-lift heat pump for high-power spacecraft thermal control The low-lift heat pump was designed to provide 25 kW of cooling at 303 K and transport this waste heat to a radiator for heat rejection. To accomplish this, a demonstration heat pump with an evaporation temperature of 298 K and a condensing temperature of 301 K was designed and built. HFC-227ea was the working fluid. This effort resulted in optimization of the centrifugal compressor impeller, diffuser, and shroud designs through extensive experimental testing. The detailed design of a magnetic bearing centrifugal compressor was completed. A prototype heat pump thermal control system was designed and fabricated which contained prototypical cold plate and condenser designs. This prototype system was extensively tested and demonstrated to measure performance parameters such as power consumption, cooling capacity, system size and mass, and other key parameters. Finally, the experimental performance was input into the theoretical trade study allowing for a comparison of the actual performance of the low-lift heat pump to a single-phase pumped loop. Inputting the experimental low-lift heat pump performance into the trade study showed that the low-lift heat pump still has lower system mass than the single-phase pumped loop for all space temperatures considered. The experimental results very closely match the theoretical results used in the trade study.

  16. Hybrid Cooling Loop Technology for Robust High Heat Flux Cooling Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced Cooling Technologies, Inc. proposes to develop a hybrid cooling loop technology for space thermal control. The proposed technology combines the high heat...

  17. CTE-Matched, Liquid-Cooled, High Thermal Conductivity Heat Sink Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose the development of a CTE-matched, liquid-cooled, high thermal conductivity heat sink for use in spacecraft thermal management applications. The material...

  18. High heat flux capabilities of the Magnum-PSI linear plasma device

    Energy Technology Data Exchange (ETDEWEB)

    De Temmerman, G., E-mail: g.c.detemmerman@differ.nl; Berg, M.A. van den; Scholten, J.; Lof, A.; Meiden, H.J. van der; Eck, H.J.N. van; Morgan, T.W.; Kruijf, T.M. de; Zeijlmans van Emmichoven, P.A.; Zielinski, J.J.

    2013-10-15

    Magnum-PSI is an advanced linear plasma device uniquely capable of producing plasma conditions similar to those expected in the divertor of ITER both steady-state and transients. The machine is designed both for fundamental studies of plasma–surface interactions under high heat and particle fluxes, and as a high-heat flux facility for the tests of plasma-facing components under realistic plasma conditions. To study the effects of transient heat loads on a plasma-facing surface, a novel pulsed plasma source system as well as a high power laser is available. In this article, we will describe the capabilities of Magnum-PSI for high-heat flux tests of plasma-facing materials.

  19. High performance felt-metal-wick heat pipe for solar receivers

    Science.gov (United States)

    Andraka, Charles E.; Moss, Timothy A.; Baturkin, Volodymyr; Zaripov, Vladlen; Nishchyk, Oleksandr

    2016-05-01

    Sodium heat pipes have been identified as a potentially effective heat transport approach for CSP systems that require near-isothermal input to power cycles or storage, such as dish Stirling and highly recuperated reheat-cycle supercritical CO2 turbines. Heat pipes offer high heat flux capabilities, leading to small receivers, as well as low exergetic losses through isothermal coupling with the engine. Sandia developed a felt metal wick approach in the 1990's, and demonstrated very high performance1. However, multiple durability issues arose, primarily the structural collapse of the wick at temperature over short time periods. NTUU developed several methods of improving robustness of the wick2, but the resulting wick had limited performance capabilities. For application to CSP systems, the wick structures must retain high heat pipe performance with robustness for long term operation. In this paper we present our findings in developing an optimal balance between performance and ruggedness, including operation of a laboratory-scale heat pipe for over 5500 hours so far. Application of heat pipes to dish-Stirling systems has been shown to increase performance as much as 20%3, and application to supercritical CO2 systems has been proposed.

  20. High performance heat pipes. Final technical report, June 1, 1978--June 30, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Eastman, G.Y.

    1979-06-30

    The report describes a program to develop and demonstrate in the 600 to 1600 C temperature range the heat transfer potential of heat pipes using a novel, high performance wick structure. The tunnel wick as conceived at Thermacore makes use of the high capillary pressure provided by the sinterng of finely divided metal powders. Low resistance liquid flow passages, or tunnels, are formed within the sintered powder. Theoretical analysis predicts higher performance for these structures than any demonstrated in the world to date.

  1. A high-temperature high-pressure calorimeter for determining heats of solution up to 623 K.

    Science.gov (United States)

    Djamali, Essmaiil; Turner, Peter J; Murray, Richard C; Cobble, James W

    2010-07-01

    A high-temperature high-pressure isoperibol calorimeter for determining the heats of solution and reaction of very dilute substances in water (10(-4) m) at temperatures up to 623 K is described. The energies of vaporization of water at steam saturation pressure were measured as a function of temperature and the results agree with the corresponding values from steam tables to better than 0.08+/-0.18%. The novelties of the present instrument relative to flow type heat capacity calorimeters are that measurements can be made at orders of magnitude lower concentrations and that measurement of heat of reaction involving solids or gases or in the presence of high concentrations of supporting electrolytes, acids, and bases is possible. Furthermore, the advantage of using enthalpy data over heat capacity data for calculations of the standard state Gibbs free energies of electrolytes is that the experimental heat data of this research need only be integrated once to derive higher temperature free energy data from lower temperatures. The derived heat capacities can be used mathematically to obtain free energies by double integration. However, the resulting errors are much smaller than if experimental aqueous heat capacities were used for the integrations.

  2. Performance of MgO:PPLN, KTA, and KNbO₃ for mid-wave infrared broadband parametric amplification at high average power.

    Science.gov (United States)

    Baudisch, M; Hemmer, M; Pires, H; Biegert, J

    2014-10-15

    The performance of potassium niobate (KNbO₃), MgO-doped periodically poled lithium niobate (MgO:PPLN), and potassium titanyl arsenate (KTA) were experimentally compared for broadband mid-wave infrared parametric amplification at a high repetition rate. The seed pulses, with an energy of 6.5 μJ, were amplified using 410 μJ pump energy at 1064 nm to a maximum pulse energy of 28.9 μJ at 3 μm wavelength and at a 160 kHz repetition rate in MgO:PPLN while supporting a transform limited duration of 73 fs. The high average powers of the interacting beams used in this study revealed average power-induced processes that limit the scaling of optical parametric amplification in MgO:PPLN; the pump peak intensity was limited to 3.8  GW/cm² due to nonpermanent beam reshaping, whereas in KNbO₃ an absorption-induced temperature gradient in the crystal led to permanent internal distortions in the crystal structure when operated above a pump peak intensity of 14.4  GW/cm².

  3. A highly detailed FEM volume conductor model based on the ICBM152 average head template for EEG source imaging and TCS targeting.

    Science.gov (United States)

    Haufe, Stefan; Huang, Yu; Parra, Lucas C

    2015-08-01

    In electroencephalographic (EEG) source imaging as well as in transcranial current stimulation (TCS), it is common to model the head using either three-shell boundary element (BEM) or more accurate finite element (FEM) volume conductor models. Since building FEMs is computationally demanding and labor intensive, they are often extensively reused as templates even for subjects with mismatching anatomies. BEMs can in principle be used to efficiently build individual volume conductor models; however, the limiting factor for such individualization are the high acquisition costs of structural magnetic resonance images. Here, we build a highly detailed (0.5mm(3) resolution, 6 tissue type segmentation, 231 electrodes) FEM based on the ICBM152 template, a nonlinear average of 152 adult human heads, which we call ICBM-NY. We show that, through more realistic electrical modeling, our model is similarly accurate as individual BEMs. Moreover, through using an unbiased population average, our model is also more accurate than FEMs built from mismatching individual anatomies. Our model is made available in Matlab format.

  4. The Influence of Non-Uniform High Heat Flux on Thermal Stress of Thermoelectric Power Generator

    Directory of Open Access Journals (Sweden)

    Tingzhen Ming

    2015-11-01

    Full Text Available A thermoelectric generator (TEG device which uses solar energy as heat source would achieve higher efficiency if there is a higher temperature difference between the hot-cold ends. However, higher temperature or higher heat flux being imposed upon the hot end will cause strong thermal stress, which will have a negative influence on the life cycle of the thermoelectric module. Meanwhile, in order to get high heat flux, a Fresnel lens is required to concentrate solar energy, which will cause non-uniformity of heat flux on the hot end of the TEG and further influence the thermal stress of the device. This phenomenon is very common in solar TEG devices but seldom research work has been reported. In this paper, numerical analysis on the heat transfer and thermal stress performance of a TEG module has been performed considering the variation on the power of the heat flux being imposed upon the hot-end; the influence of non-uniform high heat flux on thermal stress has also been analyzed. It is found that non-uniformity of high heat flux being imposed upon the hot end has a significant effect on the thermal stress of TEG and life expectation of the device. Taking the uniformity of 100% as standard, when the heating uniformity is 70%, 50%, 30%, and 10%, respectively, the maximum thermal stress of TEG module increased by 3%, 6%, 12%, and 22% respectively. If we increase the heat flux on the hot end, the influence of non-uniformity on the thermal stress will be more remarkable.

  5. Terbium gallium garnet ceramic-based Faraday isolator with compensation of thermally induced depolarization for high-energy pulsed lasers with kilowatt average power

    Science.gov (United States)

    Yasuhara, Ryo; Snetkov, Ilya; Starobor, Alexey; Palashov, Oleg

    2014-12-01

    A scalable aperture Faraday isolator for high-energy pulsed lasers with kW-level average power was demonstrated using terbium gallium garnet ceramics with water cooling and compensation of thermally induced depolarization in a magnetic field. An isolation ratio of 35 dB (depolarization ratio γ of 3.4 × 10-4) was experimentally observed at a maximum laser power of 740 W. By using this result, we estimated that this isolator maintains an isolation ratio of 30 dB for laser powers of up to 2.7 kW. Our results provide the solution for achieving optical isolation in high-energy (100 J to kJ) laser systems with a repetition rate greater than 10 Hz.

  6. Implementation of a reference-scaled average bioequivalence approach for highly variable generic drug products by the US Food and Drug Administration.

    Science.gov (United States)

    Davit, Barbara M; Chen, Mei-Ling; Conner, Dale P; Haidar, Sam H; Kim, Stephanie; Lee, Christina H; Lionberger, Robert A; Makhlouf, Fairouz T; Nwakama, Patrick E; Patel, Devvrat T; Schuirmann, Donald J; Yu, Lawrence X

    2012-12-01

    Highly variable (HV) drugs are defined as those for which within-subject variability (%CV) in bioequivalence (BE) measures is 30% or greater. Because of this high variability, studies designed to show whether generic HV drugs are bioequivalent to their corresponding HV reference drugs may need to enroll large numbers of subjects even when the products have no significant mean differences. To avoid unnecessary human testing, the US Food and Drug Administration's Office of Generic Drugs developed a reference-scaled average bioequivalence (RSABE) approach, whereby the BE acceptance limits are scaled to the variability of the reference product. For an acceptable RSABE study, an HV generic drug product must meet the scaled BE limit and a point estimate constraint. The approach has been implemented successfully. To date, the RSABE approach has supported four full approvals and one tentative approval of HV generic drug products.

  7. Residual thermal stress of a mounted KDP crystal after cooling and its effects on second harmonic generation of a high-average-power laser

    Science.gov (United States)

    Su, Ruifeng; Liu, Haitao; Liang, Yingchun; Yu, Fuli

    2017-01-01

    Thermal problems are huge challenges for solid state lasers that are interested in high output power, cooling of the nonlinear optics is insufficient to completely solve the problem of thermally induced stress, as residual thermal stress remains after cooling, which is first proposed, to the best of our knowledge. In this paper a comprehensive model incorporating principles of thermodynamics, mechanics and optics is proposed, and it is used to study the residual thermal stress of a mounted KDP crystal after cooling process from mechanical perspective, along with the effects of the residual thermal stress on the second harmonic generation (SHG) efficiency of a high-average-power laser. Effects of the structural parameters of the mounting configuration of the KDP crystal on the residual thermal stress are characterized, as well as the SHG efficiency. The numerical results demonstrate the feasibility of solving the problems of residual thermal stress from the perspective on structural design of mounting configuration.

  8. Effect of low and high heating rates on reaction path of Ni(V)/Al multilayer

    Energy Technology Data Exchange (ETDEWEB)

    Maj, Łukasz, E-mail: l.maj@imim.pl [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta St., 30-059 Kraków (Poland); Morgiel, Jerzy; Szlezynger, Maciej [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta St., 30-059 Kraków (Poland); Bała, Piotr; Cios, Grzegorz [AGH University of Science and Technology, Academic Centre for Materials and Nanotechnology, 30 Kawiory St., 30-055 Kraków (Poland)

    2017-06-01

    The effect of heating rates of Ni(V)/Al NanoFoils{sup ®} was investigated with transmission electron microscopy (TEM). The Ni(V)/Al were subjected to heating by using differential scanning calorimetry (DSC), in-situ TEM or electric pulse. Local chemical analysis was carried out using energy dispersive X-ray spectroscopy (EDS). Phase analysis was done with X-ray diffractions (XRD) and selected area electron diffractions (SAED). The experiments showed that slow heating in DSC results in development of separate exothermic effects at ∼230 °C, ∼280 °C and ∼390 °C, corresponding to precipitation of Al{sub 3}Ni, Al{sub 3}Ni{sub 2} and NiAl phases, respectively, i.e. like in vanadium free Ni/Al multilayers. Further heating to 700 °C allowed to obtain a single phase NiAl foil. The average grain size (g.s.) of NiAl phase produced in the DSC heat treated foil was comparable with the Ni(V)/Al multilayer period (∼50 nm), whereas in the case of reaction initiated with electric pulse the g.s. was in the micrometer range. Upon slow heating vanadium tends to segregate to zones parallel to the original multilayer internal interfaces, while in SHS process vanadium-rich phases precipitates at grain boundaries of the NiAl phase. - Highlights: • Peaks in DSC heating of Ni(V)/Al were explained by in-situ TEM observations. • Nucleation of Al{sub 3}Ni, Al{sub 3}Ni{sub 2} and NiAl at slow heating of Ni(V)/Al was documented. • Near surface NiAl obtained from NanoFoil show Ag precipitates at grain boundaries.

  9. On-Line Life Monitoring Technique for Tube Bundles of Boiler High-Temperature Heating Surface

    Institute of Scientific and Technical Information of China (English)

    Yang Dong; Wang Zhongyuan

    2005-01-01

    High-temperature heating surface such as superheater and reheater of large-sized utility boiler all experiences a relatively severe working conditions. The failure of boiler tubes will directly impact the safe and economic operation of boiler. An on-line life monitoring model of high-temperature heating surface was set up according to the well-known L-M formula of the creep damages. The tube wall metal temperature and working stress was measured by on-line monitoring, and with this model, the real-time calculation of the life expenditure of the heating surface tube bundles were realized. Based on the technique the on-line life monitoring and management system of high-temperature heating surface was developed for a 300 MW utility boiler. An effective device was thus suggested for the implementation of the safe operation and the condition-based maintenance of utility boilers.

  10. [Can microorganisms survive upon high-temperature heating during the interplanetary transfer by meteorites?].

    Science.gov (United States)

    Pavlov, A K; Shelegedin, V N; Kogan, V T; Pavlov, A A; Vdovina, M A; Tret'iakov, A V

    2007-01-01

    One of the most important aspects of the problem of life transfer in the cosmic space is the resistance of microorganisms to high-temperature heating during the launch and entry into the atmosphere. The high-temperature limits of the survival of microorganisms were studied under conditions modeling the laungh from the Mars and the landing on the Earth. Two strain of E. coli K12 exposed to short heating pulse were studied in order to tind out if they could resist high temperature while being in the desiccated state. The procedure was performed in vacuum. It was found that a fraction of bacteria survive heating pulses up to 250 degrees C in vacuum, while similar heating at normal atmospheric pressure leads to the total sterilization of samples.

  11. Thermal Performance of a Large Low Flow Solar Heating System with a Highly Thermally Stratified Tank

    DEFF Research Database (Denmark)

    Furbo, Simon; Vejen, Niels Kristian; Shah, Louise Jivan

    2005-01-01

    are facing west. The collector tilt is 15° from horizontal for all collectors. Both the east-facing and the west-facing collectors have their own solar collector loop, circulation pump, external heat exchanger and control system. The external heat exchangers are used to transfer the heat from the solar...... collector fluid to the domestic water. The domestic water is pumped from the bottom of the hot-water tank to the heat exchanger and back to the hot-water tank through stratification inlet pipes. The return flow from the DHW circulation pipe also enters the tank through stratification inlet pipes. The tank...... performance and for the excellent utilization of the solar radiation is the high hot-water consumption and the good system design making use of external heat exchangers and stratification inlet pipes....

  12. Influence of low- and high-frequency heating on biodegrading microorganisms in soil: microbial degradation.

    Science.gov (United States)

    Roland, Ulf; Holzer, Frank; Kopinke, Frank-Dieter

    2013-01-01

    The influence of low-frequency (50 Hz) resistive and high-frequency (13.56 MHz, radio-frequency) dielectric heating in comparison to conventional heating on the microbial degradation of pollutants in soil was studied. The investigation of the biodegradation of model substances (benzoic acid, acetic acid, glucose, sodium acetate) added to a standard soil showed no significant influence of the electrical heating methods when compared with samples heated to the same temperature in a water bath. Therefore, a hindrance of the microbial degradation could be excluded as it was done for soil respiration in a previous study. This finding is especially relevant for the application of these electrical heating methods for thermally enhanced soil bioremediation as an option for making in situ or ex situ clean-up processes more efficient.

  13. Heat-stop structure design with high cooling efficiency for large ground-based solar telescope.

    Science.gov (United States)

    Liu, Yangyi; Gu, Naiting; Rao, Changhui; Li, Cheng

    2015-07-20

    A heat-stop is one of the most important thermal control devices for a large ground-based solar telescope. For controlling the internal seeing effect, the temperature difference between the heat-stop and the ambient environment needs to be reduced, and a heat-stop with high cooling efficiency is required. In this paper, a novel design concept for the heat-stop, in which a multichannel loop cooling system is utilized to obtain higher cooling efficiency, is proposed. To validate the design, we analyze and compare the cooling efficiency for the multichannel and existing single-channel loop cooling system under the same conditions. Comparative results show that the new design obviously enhances the cooling efficiency of the heat-stop, and the novel design based on the multichannel loop cooling system is obviously better than the existing design by increasing the thermal transfer coefficient.

  14. An assessment of high school students' conceptual structures of heat and temperature through concept maps

    Science.gov (United States)

    Aykutlu, Isil; Bezen, Sevim; Bayrak, Celal

    2017-02-01

    This study is a qualitative one conducted in order to determine 9th, 10th, and 11th grade high school students' conceptual structures of heat and temperature through concept maps. The study was realized with the participation of a total of 80 students. As data gathering tool, a concept map developed by the researchers, which includes such items as heat, temperature, and matter, was used. Students were asked to form a concept map by using the concepts in the form and the concepts they thought were related with these. Data obtained from the research was analyzed via content analysis. As a result of the study, it was determined that students have misconceptions and lack of knowledge of heat and temperature. Lastly, the following can be given as examples of students' misconceptions or lack of knowledge: they think temperature comes into being as a result of heat and that heat is a kind of energy.

  15. Empirical Method for the Prediction of Heat of Formation of Organic High Energy Molecules

    Directory of Open Access Journals (Sweden)

    Sushanta Das

    2006-04-01

    Full Text Available An empirical method based on additive procedures is proposed for estimating the heats offormation of aliphatic, aromatic, and ring molecules containing nitro and other energetic groupsat standard state. The method uses only molecular structural information. Calculation of heatof formation is carried out in three stages, first the heat of formation for gaseous state is calculated,followed by incorporation of heat of vapourisation/sublimation, and finally, corrections are donefor interactions. Some interaction terms, based on hydrogen bonding strength for variouscompounds and experimental heat of formation of isomeric compounds, are also proposed. Theresults are in good agreement with the experimentally determined values. The method providesquick and sufficiently accurate values of heat of formation of organic high energy molecules.

  16. High-Temperature Heat Treatment Study on a Large-Grain Nb Cavity

    Energy Technology Data Exchange (ETDEWEB)

    G. Ciovati, P. Dhakal, R. Myneni, P. Maheshwari, F.A. Stevie

    2011-07-01

    Improvement of the cavity performance by a high-temperature heat-treatment without subsequent chemical etching have been reported for large-grain Nb cavities treated by buffered chemical polishing, as well as for a fine-grain cavity treated by vertical electropolishing. Changes in the quality factor, Q{sub 0}, and maximum peak surface magnetic field achieved in a large-grain Nb single-cell cavity have been determined as a function of the heat treatment temperature, between 600 °C and 1200 °C. The highest Q{sub 0} improvement of about 30% was obtained after heat-treatment at 800 °C-1000 °C. Measurements by secondary ion mass spectrometry on large-grain samples heat-treated with the cavity showed large reduction of hydrogen concentration after heat treatment.

  17. Waste Heat Recovery from High Temperature Off-Gases from Electric Arc Furnace

    Energy Technology Data Exchange (ETDEWEB)

    Nimbalkar, Sachin U [ORNL; Thekdi, Arvind [E3M Inc; Keiser, James R [ORNL; Storey, John Morse [ORNL

    2014-01-01

    This article presents a study and review of available waste heat in high temperature Electric Arc Furnace (EAF) off gases and heat recovery techniques/methods from these gases. It gives details of the quality and quantity of the sensible and chemical waste heat in typical EAF off gases, energy savings potential by recovering part of this heat, a comprehensive review of currently used waste heat recovery methods and potential for use of advanced designs to achieve a much higher level of heat recovery including scrap preheating, steam production and electric power generation. Based on our preliminary analysis, currently, for all electric arc furnaces used in the US steel industry, the energy savings potential is equivalent to approximately 31 trillion Btu per year or 32.7 peta Joules per year (approximately $182 million US dollars/year). This article describes the EAF off-gas enthalpy model developed at Oak Ridge National Laboratory (ORNL) to calculate available and recoverable heat energy for a given stream of exhaust gases coming out of one or multiple EAF furnaces. This Excel based model calculates sensible and chemical enthalpy of the EAF off-gases during tap to tap time accounting for variation in quantity and quality of off gases. The model can be used to estimate energy saved through scrap preheating and other possible uses such as steam generation and electric power generation using off gas waste heat. This article includes a review of the historical development of existing waste heat recovery methods, their operations, and advantages/limitations of these methods. This paper also describes a program to develop and test advanced concepts for scrap preheating, steam production and electricity generation through use of waste heat recovery from the chemical and sensible heat contained in the EAF off gases with addition of minimum amount of dilution or cooling air upstream of pollution control equipment such as bag houses.

  18. Manufacturing and High Heat Flux Testing of Brazed Flat-Type W/CuCrZr Plasma Facing Components

    Science.gov (United States)

    Lian, Youyun; Liu, Xiang; Feng, Fan; Chen, Lei; Cheng, Zhengkui; Wang, Jin; Chen, Jiming

    2016-02-01

    Water-cooled flat-type W/CuCrZr plasma facing components with an interlayer of oxygen-free copper (OFC) have been developed by using vacuum brazing route. The OFC layer for the accommodation of thermal stresses was cast onto the surface of W at a temperature range of 1150 °C-1200 °C in a vacuum furnace. The W/OFC cast tiles were vacuum brazed to a CuCrZr heat sink at 940 °C using the silver-free filler material CuMnSiCr. The microstructure, bonding strength, and high heat flux properties of the brazed W/CuCrZr joint samples were investigated. The W/Cu joint exhibits an average tensile strength of 134 MPa, which is about the same strength as pure annealed copper. High heat flux tests were performed in the electron beam facility EMS-60. Experimental results indicated that the brazed W/CuCrZr mock-up experienced screening tests of up to 15 MW/m2 and cyclic tests of 9 MW/m2 for 1000 cycles without visible damage. supported by National Natural Science Foundation of China (No. 11205049) and the National Magnetic Confinement Fusion Science Program of China (No. 2011GB110004)

  19. A high power, Coated Particle Fuel Compact Radioisotope Heat Unit

    Science.gov (United States)

    King, Jeffrey C.; El-Genk, Mohamed S.

    2001-02-01

    A Coated Particle Fuel Compact, Radioisotope Heater Unit (CPFC-RHU) is proposed, which is capable of generating thermal power in excess of 27 W. This power output is more than four times that of a Hexa-RHU, which generates only six watts of thermal power. The design of the CPFC-RHU is identical to that of the Hexa-RHU, except that the six Pt-30Rh clad fuel pellets and the POCO graphite support in the latter are replaced with single-sized, ZrC coated, 238PuO2 fuel particles ~500 μm in diameter. In addition to fully retaining the helium gas generated by the radioactive decay of the fuel, the CPFC offers promise for enhanced safety. Thermal analyses of the CPFC-RHU show that while the Hexa-RHU is suitable for use in a radioisotope power system (RPS) operating at a converter hot-side temperature of 473 K, the CPFC-RHU could also be used at higher temperatures of 773 K and 973 K with a thermal efficiency >60%. Even at a 473 K converter hot-side temperature, the CPFC-RHU offers higher thermal efficiency (>90%) than the Hexa-RHU (~75%). The CPFC-RHU final design provides constant temperature, with almost uniform radial heat flux to the converter, for enhanced performance, better integration, and higher overall efficiency of the RPS. The present CPFC-RHU fills a gap in the power needs for future space missions requiring electric power of 1-15 W, from a single RPS. .

  20. Very High Temperature Test of Alloy617 Compact Heat Exchanger in Helium Experimental Loop

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chan Soo; Park, Byung-Ha; Kim, Eung-Seon [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    The Intermediate Heat eXchanger (IHX) is a key-challenged high temperature component which determines the efficiency and the economy of VHTR system. Heat generated in the VHTR fuel block is transferred from the VHTR to the intermediate loop through IHX. In the present, the shell-helical tube heat exchanger is generally used as IHX of the helium cooled reactor. Recently, a Printed Circuit Heat Exchanger (PCHE) is one of the candidates for the IHX in a VHTR because its operation temperature and pressure are larger than any other compact heat exchanger types. These test results show that there is no problem in operation of HELP at the very high temperature experimental condition and the alloy617 compact heat exchanger can be operated in the very high temperature condition above 850℃. In the future, the high temperature structural analysis will be studied to estimate the thermal stress during transient and thermal shock condition. The conditions and evaluation standard for the alloy 617 diffusion bonding will be minutely studied to fabricate the large-scale PCHE for the high temperature condition.

  1. Analysis for Heat Transfer in a High Current-Passing Carbon Nanosphere Using Nontraditional Thermal Transport Model.

    Science.gov (United States)

    Hol C Y; Chen, B C; Tsai, Y H; Ma, C; Wen, M Y

    2015-11-01

    This paper investigates the thermal transport in hollow microscale and nanoscale spheres subject to electrical heat source using nontraditional thermal transport model. Working as supercapacitor electrodes, carbon hollow micrometer- and nanometer-sized spheres needs excellent heat transfer characteristics to maintain high specific capacitance, long cycle life, and high power density. In the nanoscale regime, the prediction of heat transfer from the traditional heat conduction equation based on Fourier's law deviates from the measured data. Consequently, the electrical heat source-induced heat transfer characteristics in hollow micrometer- and nanometer-sized spheres are studied using nontraditional thermal transport model. The effects of parameters on heat transfer in the hollow micrometer- and nanometer-sized spheres are discussed in this study. The results reveal that the heat transferred into the spherical interior, temperature and heat flux in the hollow sphere decrease with the increasing Knudsen number when the radius of sphere is comparable to the mean free path of heat carriers.

  2. Final Report for Project titled High Thermal Conductivity Polymer Composites for Low-Cost Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Thibaud-Erkey, Catherine [United Technologies reserach Center, East Hartford, CT (United States); Alahyari, Abbas [United Technologies reserach Center, East Hartford, CT (United States)

    2016-12-28

    Heat exchangers (HXs) are critical components in a wide range of heat transfer applications, from HVAC (Heating Ventilation and Cooling) to automobiles to manufacturing plants. They require materials capable of transferring heat at high rates while also minimizing thermal expansion over the usage temperature range. Conventionally, metals are used for applications where effective and efficient heat exchange is required, since many metals exhibit thermal conductivity over 100 W/m K. While metal HXs are constantly being improved, they still have some inherent drawbacks due to their metal construction, in particular corrosion. Polymeric material can offer solution to such durability issues and allow designs that cannot be afforded by metal construction either due to complexity or cost. A major drawback of polymeric material is their low thermal conductivity (0.1-0.5? W/mK) that would lead to large system size. Recent improvements in the area of filled polymers have highlighted the possibility to greatly improve the thermal conductivity of polymeric materials while retaining their inherent manufacturing advantage, and have been applied to heat sink applications. Therefore, the objective of this project was to develop a robust review of materials for the manufacturing of industrial and commercial non-metallic heat exchangers. This review consisted of material identification, literature evaluation, as well as empirical and model characterization, resulting in a database of relevant material properties and characteristics to provide guidance for future heat exchanger development.

  3. Temporal Changes in Extreme High Temerature, Heat Waves in Istanbul Between 1960-2014

    Science.gov (United States)

    Yürük, C.; Ünal, Y. S.; Bilgen, S. I.; Menteş, Ş. S.; İncecik, S.

    2015-12-01

    Climate change has crucial effects on cities and especially for informal settlements, urban poor and other vulnerable groups by influencing human health, assets and livelihoods. These impacts directly result from the variations in temperature and precipitation, and emergence of heat waves, droughts, floods and fires (IPCC, 2014). Summertime episodes with extremely high air temperatures which last for several days or longer are addressed to as heat waves and affect the weather and climate in the globe. The aim of this study is to analyze the occurrence of heat waves in terms of quantity, duration and frequency and also to evaluate the accuracy of the COSMO-CLM (CCLM) model in reproducing the characteristics of heat waves in Istanbul. The summer maximum temperatures of six Turkish State Meteorological Service (TSMS) stations are selected between 1960 and 2014 to estimate the characteristics of heat waves in Istanbul. We define the heat wave if the maximum temperatures exceed a threshold value for at least three consecutive days. The threshold value is determined as 30.5 from the 90th percentile of all six station's observations. Then it is used in the detection of the hot days, heat waves and their durations. The results show that not only the number of heat waves but also duration of heat waves increase towards the end of the study period. Especially, a significant increase in heat wave events is evident after 1990s. In 2012, the number of hot days reaches the maximum value in all stations and Kartal station located southern part of city, has the highest value of 60 hot days. Furthermore, Kartal as an urban area in the Asian side of the city, exhibits highest heat wave duration with 18 consecutive days in 1998. To estimate the relationship between urban heat island intensity and the heat waves, we examined data at 43 stations collected by Disaster Coordination Center and TSMS between 2007 and 2012. Urban heat island phenomenon is found to be related to higher

  4. Differences of hormones involved in adipose metabolism and lactation between high and low producing Holstein cows during heat stress

    Directory of Open Access Journals (Sweden)

    Mingzi Qu

    2015-12-01

    Full Text Available The experiment was conducted to evaluate hormonal involvement in the adipose metabolism and lactation between high and low producing dairy cows in a hot environment. Forty Holstein healthy cows with a similar parity were used and assigned into high producing group (average production 41.44 ± 2.25 kg/d and low producing group (average production 29.92 ± 1.02 kg/d with 20 cows in each group. Blood samples were collected from caudal vein to determine the difference of hormones related to adipose metabolism and lactation. The highest, lowest, and average temperature humidity index (THI, recorded as 84.02, 79.35 and 81.89, respectively, indicated that cows were at the state of high heat stress. No significant differences between high and low producing groups were observed in the levels of nonestesterified fatty acid (NEFA, β-hydroxybutyrate (β-OHB, total cholesterol (TCHO, and insulin (INS (P > 0.05. However, the very low density lipoprotein (VLDL, apolipoprotein B100 (apoB-100, high-density lipoprotein (HDL-C and estrogen (E2 concentrations in high producing group were significantly higher than those of low producing group (P  0.05, whereas high producing group had a rise in the insulin-like growth factor-1 (IGF-1 level compared with low producing group (P < 0.05. These results indicated that, during summer, high and low producing dairy cows have similar levels of lipid catabolism, but high producing dairy cows have advantages in outputting hepatic triglyceride (TG.

  5. Highly Reproducible Perovskite Solar Cells with Average Efficiency of 18.3% and Best Efficiency of 19.7% Fabricated via Lewis Base Adduct of Lead(II) Iodide.

    Science.gov (United States)

    Ahn, Namyoung; Son, Dae-Yong; Jang, In-Hyuk; Kang, Seong Min; Choi, Mansoo; Park, Nam-Gyu

    2015-07-15

    High efficiency perovskite solar cells were fabricated reproducibly via Lewis base adduct of lead(II) iodide. PbI2 was dissolved in N,N-dimethyformamide with equimolar N,N-dimethyl sulfoxide (DMSO) and CH3NH3I. Stretching vibration of S═O appeared at 1045 cm(-1) for bare DMSO, which was shifted to 1020 and 1015 cm(-1) upon reacting DMSO with PbI2 and PbI2 + CH3NH3I, respectively, indicative of forming the adduct of PbI2·DMSO and CH3NH3I·PbI2·DMSO due to interaction between Lewis base DMSO and/or iodide (I(-)) and Lewis acid PbI2. Spin-coating of a DMF solution containing PbI2, CH3NH3I, and DMSO (1:1:1 mol %) formed a transparent adduct film, which was converted to a dark brown film upon heating at low temperature of 65 °C for 1 min due to removal of the volatile DMSO from the adduct. The adduct-induced CH3NH3PbI3 exhibited high charge extraction characteristics with hole mobility as high as 3.9 × 10(-3) cm(2)/(V s) and slow recombination rate. Average power conversion efficiency (PCE) of 18.3% was achieved from 41 cells and the best PCE of 19.7% was attained via adduct approach.

  6. Small-scale fluctuations in barium drifts at high latitudes and associated Joule heating effects

    Science.gov (United States)

    Hurd, L. D.; Larsen, M. F.

    2016-01-01

    Most previous estimates of Joule heating rates, especially the contribution of small-scale structure in the high-latitude ionosphere, have been based on incoherent scatter or coherent scatter radar measurements. An alternative estimate can be found from the plasma drifts obtained from ionized barium clouds released from sounding rockets. We have used barium drift data from three experiments to estimate Joule heating rates in the high-latitude E region for different magnetic activity levels. In particular, we are interested in the contribution of small-scale plasma drift fluctuations, corresponding to equivalent electric field fluctuations, to the local Joule heating rate on scales smaller than those typically resolved by radar or other measurements. Since Joule heating is a Lagrangian quantity, the inherently Lagrangian estimates provided by the chemical tracer measurements are a full description of the effects of electric field variance and neutral winds on the heating, differing from the Eulerian estimates of the type provided by ground-based measurements. Results suggest that the small-scale contributions to the heating can be more than a factor of 2 greater than the mean field contribution regardless of geomagnetic conditions, and at times the small-scale contribution is even larger. The high-resolution barium drift measurements, moreover, show that the fine structure in the electric field can be more variable than previous studies have reported for similar conditions. The neutral winds also affect the heating, altering the height-integrated Joule heating rates by as much as 12%, for the cases studied here, and modifying the height distribution of the heating profile as well.

  7. High Concentration of Heat Pumps in Suburban Areas and Reduction of Their Impact on the Electricity Network

    OpenAIRE

    Pruissen, O.P. van; Kamphuis, I.G.

    2011-01-01

    One of the challenges of the near future for a more renewable Dutch electricity infrastructure is the embedding of high concentrations of heat pumps in currently built domestic residences. In the Dutch situation demand of electricity occurs simultaneously with demand of heat, high electricity peak loads in the low voltage network are expected. This study focuses on domestic residences with high peak loads at substations when heating is provided merely by heat pumps with additional electric re...

  8. Formation of high-carbon abrasion-resistant surface layers when high-energy heating by high-frequency currents

    Science.gov (United States)

    Plotnikova, N. V.; Skeeba, V. Yu; Martyushev, N. V.; Miller, R. A.; Rubtsova, N. S.

    2016-11-01

    The paper shows the possibility of carburization of low-carbon steel surface layers using high-frequency currents. The mathematical modeling of carburization using high-energy heating by high-frequency currents (HEH HFC) has been carried out, the temperature fields formed during the given processing have been calculated, as well as the structural changes in the surface layers have been simulated. The features of the structure formation in the surface layers of low-carbon steel after carburizing via HEH HFC have been determined by optical and scanning microscopy, which is confirmed by the computational models. The rational mode of fusion via HEH HFC has also been determined (power density of the source qs = (1.5 ... 4.0) • 108 W m-2, (the relative travel speed of parts Vp = 5 ... 100 mm / sec), with forming the compressive retained stresses in the surface layer (σRS ≈ -300 ... -400 MPa).

  9. ITER-W monoblocks under high pulse number transient heat loads at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Loewenhoff, Th., E-mail: T.Loewenhoff@fz-juelich.de [Forschungszentrum Jülich, 52428 Jülich (Germany); Linke, J., E-mail: J.Linke@fz-juelich.de [Forschungszentrum Jülich, 52428 Jülich (Germany); Pintsuk, G., E-mail: G.Pintsuk@fz-juelich.de [Forschungszentrum Jülich, 52428 Jülich (Germany); Pitts, R.A., E-mail: Richard.Pitts@iter.org [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul-Lez-Durance (France); Riccardi, B., E-mail: Bruno.Riccardi@f4e.europa.eu [Fusion for Energy Joint Undertaking, Josep Pla No. 2 – T B3 7/01, Barcelona 08019 (Spain)

    2015-08-15

    In the context of using a full-tungsten (W) divertor for ITER, thermal shock resistance has become even more important as an issue that may potentially influence the long term performance. To address this issue a unique series of experiments has been performed on ITER-W monoblock mock ups in three EU high heat flux facilities: GLADIS (neutral beam), JUDITH 2 (electron beam) and Magnum-PSI (plasma beam). This paper discusses the JUDITH 2 experiments. Two different base temperatures, 1200 °C and 1500 °C, were chosen superimposed by ∼18,000/100,000 transient events (Δt = 0.48 ms) of 0.2 and 0.6 GW/m{sup 2}. Results showed a stronger surface deterioration at higher base temperature, quantified by an increase in roughening. This is intensified if the same test is done after preloading (exposure to high temperature without transients), especially at higher base temperature when the material recrystallizes.

  10. High thermally conductive and electrically insulating 2D boron nitride nanosheet for efficient heat dissipation of high-power transistors

    Science.gov (United States)

    Lin, Ziyuan; Liu, Chunru; Chai, Yang

    2016-12-01

    High-power transistors suffer greatly from inefficient heat dissipation of the hotspots, which elevate the local temperature and significantly degrade the performance and reliability of the high-power devices. Although various thermal management methods at package-level have been demonstrated, the heat dissipation from non-uniform hotspots at micro/nanoscale still persist in the high power transistors. Here, we develop a method for local thermal management using thermally conductive and electrical insulating few-layer hexagonal boron nitride (h-BN) as heat spreaders and thick counterpart as heat sinks. The electrically insulating characteristic of h-BN nanosheet allows it to be intimately contacted with the hotspot region that is located at the gate electrode edge near the drain side of a high-electron-mobility transistor (HEMT). The high thermal conductivity of h-BN nanosheet, which is quantitatively measured by Raman thermography, reduces the temperature of the hotspot by introducing an additional heat transporting pathway. Our DC and radio-frequency characterizations of the HEMT show the improvement of saturation current, cut-off frequency and maximum oscillation frequency. The finite element simulations show a temperature decrease of ∼32 °C at the hotspot with the use of h-BN nanosheet. This method can be further extended for the micro/nanoscale thermal management of other high-power devices.

  11. Survey of literature on convective heat transfer coefficients and recovery factors for high atmosphere thermometry

    Science.gov (United States)

    Chung, S.

    1973-01-01

    Heat transfer phenomena of rarefied gas flows is discussed based on a literature survey of analytical and experimental rarefied gas dynamics. Subsonic flows are emphasized for the purposes of meteorological thermometry in the high atmosphere. The heat transfer coefficients for three basic geometries are given in the regimes of free molecular flow, transition flow, slip flow, and continuum flow. Different types of heat phenomena, and the analysis of theoretical and experimental data are presented. The uncertainties calculated from the interpolation rule compared with the available experimental data are discussed. The recovery factor for each geometry in subsonic rarefied flows is also given.

  12. DEAP actuator and its high voltage driver for heating valve application

    DEFF Research Database (Denmark)

    Huang, Lina; Nørmølle, L. F.; Sarban, R.;

    2014-01-01

    Due to the advantages of DEAP (Dielectric Electro Active Polymer) material, such as light weight, noise free operation, high energy and power density and fast response speed, it can be applied in a variety of applications to replace the conventional transducers or actuators. This paper introduces...... DEAP actuator to the heating valve system and conducts a case study to discuss the feasible solution in designing DEAP actuator and its driver for heating valve application. First of all, the heating valves under study are briefly introduced. Then the design and the development for DEAP actuator...

  13. High temperature thermocouple and heat flux gauge using a unique thin film-hardware hot juncture

    Science.gov (United States)

    Liebert, C. H.; Holanda, R.; Hippensteele, S. A.; Andracchio, C. A.

    1984-01-01

    A special thin film-hardware material thermocouple (TC) and heat flux gauge concept for a reasonably high temperature and high flux flat plate heat transfer experiment was fabricated and tested to gauge temperatures of 911 K. This concept was developed for minimal disturbance of boundary layer temperature and flow over the plates and minimal disturbance of heat flux through the plates. Comparison of special heat flux gauge Stanton number output at steady-state conditions with benchmark literature data was good and agreement was within a calculated uncertainty of the measurement system. Also, good agreement of special TC and standard TC outputs was obtained and the results are encouraging. Oxidation of thin film thermoelements was a primary failure mode after about 5 of operation.

  14. Kinetic Hydration Heat Modeling for High-Performance Concrete Containing Limestone Powder

    Directory of Open Access Journals (Sweden)

    Xiao-Yong Wang

    2017-01-01

    Full Text Available Limestone powder is increasingly used in producing high-performance concrete in the modern concrete industry. Limestone powder blended concrete has many advantages, such as increasing the early-age strength, reducing the setting time, improving the workability, and reducing the heat of hydration. This study presents a kinetic model for modeling the hydration heat of limestone blended concrete. First, an improved hydration model is proposed which considers the dilution effect and nucleation effect due to limestone powder addition. A degree of hydration is calculated using this improved hydration model. Second, hydration heat is calculated using the degree of hydration. The effects of water to binder ratio and limestone replacement ratio on hydration heat are clarified. Third, the temperature history and temperature distribution of hardening limestone blended concrete are calculated by combining hydration model with finite element method. The analysis results generally agree with experimental results of high-performance concrete with various mixing proportions.

  15. Heat transfer and structure stress analysis of micro packaging component of high power light emitting diode

    Directory of Open Access Journals (Sweden)

    Hsu Chih-Neng

    2013-01-01

    Full Text Available This paper focuses on the heat transfer and structural stress analysis of the micro- scale packaging structure of a high-power light emitting diode. The thermal-effect and thermal-stress of light emitting diode are determined numerically. Light emitting diode is attached to the silicon substrate through the wire bonding process by using epoxy as die bond material. The silicon substrate is etched with holes at the bottom and filled with high conductivity copper material. The chip temperature and structure stress increase with input power consumption. The micro light emitting diode is mounted on the heat sink to increase the heat dissipation performance, to decrease chip temperature, to enhance the material structure reliability and safety, and to avoid structure failure as well. This paper has successfully used the finite element method to the micro-scale light emitting diode heat transfer and stress concentration at the edges through etched holes.

  16. High-efficiency gas heat pump air-conditioner equipped with absorption refrigerator

    Science.gov (United States)

    Imai, Yosuke; Ohashi, Toshinori; Okamoto, Hiroaki; Hihara, Eiji; Kawakami, Ryuichiro

    On conventional gas heat pump(GHP), waste heat from gas engine that uses as driving source is emitted into outside. So from the standpoint of efficient use of waste heat, it is assumed that waste heat from gas engine is used as driving source of absorption chiller, and high temperature condensate refrigerant in GHP is subcooled to middle temperature by cold source from absorption cycle, and as a result, GHP makes more efficiency. However, in equipping GHP with absorption cycle, downsizing and high-efficiency of absorption cycle is required. In this study, air-cooled subcooled adiabatic absorber is focused and physical phenomenon in it is analyzed, and finally one perception of the optimized designing is shown.

  17. Investigation of arterial gas occlusions. [effect of noncondensable gases on high performance heat pipes

    Science.gov (United States)

    Saaski, E. W.

    1974-01-01

    The effect of noncondensable gases on high-performance arterial heat pipes was investigated both analytically and experimentally. Models have been generated which characterize the dissolution of gases in condensate, and the diffusional loss of dissolved gases from condensate in arterial flow. These processes, and others, were used to postulate stability criteria for arterial heat pipes under isothermal and non-isothermal condensate flow conditions. A rigorous second-order gas-loaded heat pipe model, incorporating axial conduction and one-dimensional vapor transport, was produced and used for thermal and gas studies. A Freon-22 (CHCIF2) heat pipe was used with helium and xenon to validate modeling. With helium, experimental data compared well with theory. Unusual gas-control effects with xenon were attributed to high solubility.

  18. Self-heated silicon nanowires for high performance hydrogen gas detection

    Science.gov (United States)

    Ahn, Jae-Hyuk; Yun, Jeonghoon; Moon, Dong-Il; Choi, Yang-Kyu; Park, Inkyu

    2015-03-01

    Self-heated silicon nanowire sensors for high-performance, ultralow-power hydrogen detection have been developed. A top-down nanofabrication method based on well-established semiconductor manufacturing technology was utilized to fabricate silicon nanowires in wafer scale with high reproducibility and excellent compatibility with electronic readout circuits. Decoration of palladium nanoparticles onto the silicon nanowires enables sensitive and selective detection of hydrogen gas at room temperature. Self-heating of silicon nanowire sensors allows us to enhance response and recovery performances to hydrogen gas, and to reduce the influence of interfering gases such as water vapor and carbon monoxide. A short-pulsed heating during recovery was found to be effective for additional reduction of operation power as well as recovery characteristics. This self-heated silicon nanowire gas sensor will be suitable for ultralow-power applications such as mobile telecommunication devices and wireless sensing nodes.

  19. Relative Contributions of Heating and Momentum Forcing to High-Latitude Lower Thermospheric Winds

    Science.gov (United States)

    Kwak, Y. S.; Richmond, A. D.

    2015-12-01

    At high latitudes the thermospheric dynamics are gov­erned by various heat and momentum sources. Recently several modeling studies have been attempt­ed to understand the physical process that control the high-latitude lower thermospheric dynamics. Kwak and Richmond [2007] and Kwak et al. [2007] studied the momentum forcing bal­ance that are mainly responsible for maintaining the high-latitude lower thermospheric wind system by using the National Center for Atmospheric Research Thermo­sphere Ionosphere Electrodynamics General Circulation Model (NCAR TIE-GCM). Kwak and Richmond [2014] analyzed the divergence and vorticity of the high-latitude neutral wind field in the lower thermosphere during the south­ern summertime. In this study, we extend previous works by Kwak and Rich­mond [2007, 2014] and Kwak et al. [2007], which helped to better understand the physical processes maintaining thermospheric dynamics at high latitudes, and here perform a "term analysis of the potential vorticity equation" for the high-latitude neu­tral wind field in the lower thermosphere, on the basis of numerical simulations using the NCAR TIE-GCM. These analyses can provide insight into the relative strength of the heating and the momentum forcing responsible for driving rotational winds at the high-latitude lower thermosphere. The heating is the net heat including the heat transfer by downward molecular and eddy heat conduction, the absorption of solar ultraviolet (UV) and extreme ultraviolet (EUV) ra­diation, auroral heating by particles, Joule dissipation of ionospheric currents, release of chemical energy by the atomic oxygen recombination, and radiative CO2, NO and O infrared emissions. The momentum forcing is associated with the viscous force and the frictional drag force from convecting ions.

  20. Effects of Autumn and Spring Heat Waves on Seed Germination of High Mountain Plants.

    Science.gov (United States)

    Orsenigo, Simone; Abeli, Thomas; Rossi, Graziano; Bonasoni, Paolo; Pasquaretta, Cristian; Gandini, Maurizia; Mondoni, Andrea

    2015-01-01

    Alpine plants are considered to be particularly vulnerable to climate change and related extreme episodes, such as heat waves. Despite growing interest in the impact of heat waves on alpine plants, knowledge about their effects on regeneration is still fragmentary. Recruitment from seeds will be crucial for the successful migration and survival of these species and will play a key role in their future adaptation to climate change. In this study, we assessed the impacts of heat waves on the seed germination of 53 high mountain plants from the Northern Apennines (Italy). The seeds were exposed to laboratory simulations of three seasonal temperature treatments, derived from real data recorded at a meteorological station near the species growing site, which included two heat wave episodes that occurred both in spring 2003 and in autumn 2011. Moreover, to consider the effect of increasing drought conditions related to heat waves, seed germination was also investigated under four different water potentials. In the absence of heat waves, seed germination mainly occurred in spring, after seeds had experienced autumn and winter seasons. However, heat waves resulted in a significant increase of spring germination in c. 30% of the species and elicited autumn germination in 50%. When heat waves were coupled with drought, seed germination decreased in all species, but did not stop completely. Our results suggest that in the future, heat waves will affect the germination phenology of alpine plants, especially conditionally dormant and strictly cold-adapted chorotypes, by shifting the emergence time from spring to autumn and by increasing the proportion of emerged seedlings. The detrimental effects of heat waves on recruitment success is less likely to be due to the inhibition of seed germination per se, but rather due to seedling survival in seasons, and temperature and water conditions that they are not used to experiencing. Changes in the proportion and timing of emergence

  1. Review of current status of high flux heat transfer techniques. Volume I. Text + Appendix A

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, W.H.; Gordon, H.S.; Lackner, H.; Mettling, J.R.; Miller, J.E.

    1980-09-01

    The scope of this work comprised two tasks. The first was to review high heat flux technology with consideration given to heat transfer panel configuration, diagnostics techniques and coolant supply. The second task was to prepare a report describing the findings of the review, to recommend the technology offering the least uncertainty for scale-up for the MFTF-B requirement and to recommend any new or perceived requirements for R and D effort.

  2. Investigation of heat transfer in high-capacity power transformers having modifications preventing explosions

    Science.gov (United States)

    Aksenov, A. A.; Zhluktov, S. V.; Kudimov, N. F.; Son, E. E.; Savitskii, D. V.; Tretiyakova, O. N.; Shishaeva, A. S.

    2014-12-01

    Results of numerical simulation of complex conjugate heat transfer in a high power electric transformer are presented. Simulation of the flow and heat transfer inside a transformer with static blast protection was carried out. Analysis of test calculations performed in the FlowVision software suit was carried out. Comparison of the performance of created numerical model against the real experimental data from the thermal tests of the transformer was made.

  3. A dynamic model of an innovative high-temperature solar heating and cooling system

    OpenAIRE

    Buonomano Annamaria; Calise Francesco; Vicidomini Maria

    2016-01-01

    In this paper a new simulation model of a novel solar heating and cooling system based on innovative high temperature flat plate evacuated solar thermal collector is presented. The system configuration includes: flat-plate evacuated solar collectors, a double-stage LiBr-H2O absorption chiller, gas-fired auxiliary heater, a closed loop cooling tower, pumps, heat exchangers, storage tanks, valves, mixers and controllers. The novelty of this study lies in the ...

  4. Fundamental studies on enhancing heat transfer in contact zone during high efficiency grinding

    Institute of Scientific and Technical Information of China (English)

    XU; Hongjun(徐鸿钧); FU; Yucan(傅玉灿); XU; Xipeng(徐西鹏); XU; Xipeng

    2002-01-01

    On the basis of research on the thermal effect in grinding contact zone during high effi-ciency grinding, an idea of enhancing heat transfer in contact zone using high pressure water jetimpinging is advanced. Fundamental heat transfer experiments on enhancing heat transfer withhigh pressure water jet impinging were completed. The maximum speed of jet impinging reaches110m/s. The experimental results of transient and steady-state experiment prove that the criticalheat flux and the heat-transfer coefficient of water jet impinging are 70 and 30 times those of thepool boiling, respectively. Furthermore, a new grinding fluid supply system was employed to en-hance heat transfer in grinding zone by high-pressure water jet impingement during creep feedgrinding. The experimental results show that high-pressure water jet impinging has remarkablecooling effect. The temperature of the workpiece surface can be steadily kept below 100℃, whilethe workpiece is badly burnt with conventional coolant supply. The study will exploit an importantresearch orientation that has great potentialities in the high efficiency grinding. Further perfectionof this study will not only enable us to increase the available material removal rate to a new levelbut also solve the workpiece burn problem of the difficult-to-machining materials in high efficiencygrinding,

  5. Trehalose in hair care: heat styling benefits at high humidity.

    Science.gov (United States)

    Pye, Susan; Paul, Prem K C

    2012-01-01

    Human hair switches that have been treated with trehalose solution and straightened using hot irons show longevity of the straight style even in high-humidity conditions. This anti-humidity benefit is especially noticeable if the straight style has been created at low relative humidity. It is proposed that hot-iron straightening of trehalose-treated switches produces in situ glassy forms of the sugar that act as water sinks at high humidity to provide anti-humidity benefits. Adsorption isotherms and powder x-ray studies of different forms of trehalose and moisture uptake of hair treated with the sugar suggest that the ability of a glassy form of trehalose to regulate moisture in the fiber and consequently affect its viscoelastic properties is a major factor in providing long-lasting straight style in humid conditions.

  6. Potential for improvement in high heat flux HyperVapotron element performance using nanofluids

    Science.gov (United States)

    Sergis, A.; Hardalupas, Y.; Barrett, T. R.

    2013-11-01

    HyperVapotron (HV) elements have been used extensively as high heat flux beam stopping components in nuclear fusion research facilities. These water-cooled heat exchangers use a boiling heat transfer mechanism and so are inherently limited by their critical heat flux (CHF). The use of a nanofluid as the coolant, instead of water, promises to enhance the heat transfer performance of the HV and increase the CHF by a factor of 2 or 3, which would lead to a step-change improvement in the power handling capability. This paper reports on computational and experimental analyses which have indicated mechanisms for the enhanced thermal performance of nanofluids. A molecular dynamics simulation code has been developed which has identified heat transfer augmentation mechanisms that depart from classical thermodynamics associated with the presence of nanoparticles. In addition, an experiment has been conducted which uses particle image velocimetry to measure the flow field in a full-scale HV. Past studies have yielded qualitative experimental results, but the measurements reported here provide quantitative data to aid the understanding of the initial flow field inside the HV (i.e., before a heat flux is applied). Further, the experiment is conducted using both water and Al2O3-water nanofluid as the flow medium. Thus, these velocity measurements offer a first indication for potentially enhanced heat transfer in HV devices when nanofluids are used as the coolant. The improved understanding of the HV flow regime and the cooling advantage of nanofluids could assist the design of advanced high heat flux components for future fusion machines.

  7. High flux inductors for the rapid heating of steel products

    Energy Technology Data Exchange (ETDEWEB)

    Pierret, R.; Griffay, G.; Galbrun, F. [Institut de Recherches de la Siderurgie Francaise (IRSID), 78 - Saint-Germain-en-Laye (France); Hellegouaec`h, J.; Prost, G.

    1995-03-01

    To reduce investment and operating costs of electroheating processes of long products by induction, we developed a new multilayed inductor with high flux density which represents a real technological step in regard of conventional technics: 4 MV/m{sup 2} instead of 1MW/m{sup 2}, efficiency of 85% instead of 55%, compacity and low costs of maintenance. The new technology can also be used with success in flat products plants. (authors). 10 figs., 1 tab.

  8. Prototyping phase of the high heat flux scraper element of Wendelstein 7-X

    Energy Technology Data Exchange (ETDEWEB)

    Boscary, J., E-mail: jean.boscary@ipp.mpg.de [Max Planck Institute for Plasma Physics, Garching (Germany); Greuner, H. [Max Planck Institute for Plasma Physics, Garching (Germany); Ehrke, G. [Max Planck Institute for Plasma Physics, Greifswald (Germany); Böswirth, B.; Wang, Z. [Max Planck Institute for Plasma Physics, Garching (Germany); Clark, E. [University of Tennessee, Knoxville (United States); Lumsdaine, A. [Oak Ridge National Laboratory, USA National Laboratory, Oak Ridge, Tennessee (United States); Tretter, J. [Max Planck Institute for Plasma Physics, Garching (Germany); McGinnis, D.; Lore, J. [Oak Ridge National Laboratory, USA National Laboratory, Oak Ridge, Tennessee (United States); Ekici, K. [University of Tennessee, Knoxville (United States)

    2016-11-01

    Highlights: • Aim of scraper element: reduction of heat loads on high heat flux divertor ends. • Design: actively water-cooled for 20 MW/m{sup 2} local heat loads. • Technology: CFC NB31 monoblocks bonded by HIP to CuCrZr cooling tube. • Successful high heat flux testing up to 20 MW/m{sup 2}. - Abstract: The water-cooled high heat flux scraper element aims to reduce excessive heat loads on the target element ends of the actively cooled divertor of Wendelstein 7-X. Its purpose is to intercept some of the plasma fluxes both upstream and downstream before they reach the divertor surface. The scraper element has 24 identical plasma facing components (PFCs) divided into 6 modules. One module has 4 PFCs hydraulically connected in series by 2 water boxes. A PFC, 247 mm long and 28 mm wide, has 13 monoblocks made of CFC NB31 bonded by hot isostatic pressing onto a CuCrZr cooling tube equipped with a copper twisted tape. 4 full-scale prototypes of PFCs have been successfully tested in the GLADIS facility up to 20 MW/m{sup 2}. The difference observed between measured and calculated surface temperatures is probably due to the inhomogeneity of CFC properties. The design of the water box prototypes has been detailed to allow the junction between the cooling pipe of the PFCs and the water boxes by internal orbital welding. The prototypes are presently under fabrication.

  9. Effect of high-temperature heat treatment duration on the purity and microstructure of MWCNTs

    Indian Academy of Sciences (India)

    I Srikanth; N Padmavathi; P S R Prasad; P Ghosal; R K Jain; Ch Subrahmanyam

    2016-02-01

    The effect of high-temperature heat treatment on purity and structural changes of multiwalled carbon nanotubes (MWCNTs) were studied by subjecting the raw MWCNTs (pristine MWCNTs) to 2600°C for 60 and 120 min. Thermogravimetric analysis (TGA), X-ray diffraction, Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to study the effect of heat-treatment duration on the purity and structural changes of MWCNTs. Results show that high-temperature heat treatment can be used to purify MWCNTs with proper optimization of treatment time. It was observed that 60 min heat treatment of raw MWCNTs imparts high purity and structural perfection to MWCNTs, while 120 min heat treatment imparts structural degradation to MWCNTs with collapse of the innermost shells. The present study indicates that metal impurities act as moderators in controlling the degradation of MWCNTs up to certain duration, and once the metal impurities escape completely, further heat treatment degrades the structure of MWCNTs.

  10. Heat Recovery from High Temperature Slags: A Review of Chemical Methods

    Directory of Open Access Journals (Sweden)

    Yongqi Sun

    2015-03-01

    Full Text Available Waste heat recovery from high temperature slags represents the latest potential way to remarkably reduce the energy consumption and CO2 emissions of the steel industry. The molten slags, in the temperature range of 1723–1923 K, carry large amounts of high quality energy. However, the heat recovery from slags faces several fundamental challenges, including their low thermal conductivity, inside crystallization, and discontinuous availability. During past decades, various chemical methods have been exploited and performed including methane reforming, coal and biomass gasification, and direct compositional modification and utilization of slags. These methods effectively meet the challenges mentioned before and help integrate the steel industry with other industrial sectors. During the heat recovery using chemical methods, slags can act as not only heat carriers but also as catalysts and reactants, which expands the field of utilization of slags. Fuel gas production using the waste heat accounts for the main R&D trend, through which the thermal heat in the slag could be transformed into high quality chemical energy in the fuel gas. Moreover, these chemical methods should be extended to an industrial scale to realize their commercial application, which is the only way by which the substantial energy in the slags could be extracted, i.e., amounting to 16 million tons of standard coal in China.

  11. NGNP/HTE full-power operation at reduced high-temperature heat exchanger temperatures.

    Energy Technology Data Exchange (ETDEWEB)

    VIlim, R.; Nuclear Engineering Division

    2009-03-12

    Operation of the Next Generation Nuclear Plant (NGNP) with reduced reactor outlet temperature at full power was investigated for the High Temperature Electrolysis (HTE) hydrogen-production application. The foremost challenge for operation at design temperature is achieving an acceptably long service life for heat exchangers. In both the Intermediate Heat Exchanger (IHX) and the Process Heat Exchanger (PHX) (referred to collectively as high temperature heat exchangers) a pressure differential of several MPa exists with temperatures at or above 850 C. Thermal creep of the heat exchanger channel wall may severely limit heat exchanger life depending on the alloy selected. This report investigates plant performance with IHX temperatures reduced by lowering reactor outlet temperature. The objective is to lower the temperature in heat transfer channels to the point where existing materials can meet the 40 year lifetime needed for this component. A conservative estimate for this temperature is believed to be about 700 C. The reactor outlet temperature was reduced from 850 C to 700 C while maintaining reactor power at 600 MWt and high pressure compressor outlet at 7 MPa. We included a previously reported design option for reducing temperature at the PHX. Heat exchanger lengths were adjusted to reflect the change in performance resulting from coolant property changes and from resizing related to operating-point change. Turbomachine parameters were also optimized for the new operating condition. An integrated optimization of the complete system including heat transfer equipment was not performed. It is estimated, however, that by performing a pinch analysis the combined plant efficiency can be increased from 35.5 percent obtained in this report to a value between 38.5 and 40.1 percent. Then after normalizing for a more than three percent decrease in commodities inventory compared to the reference plant, the commodities-normalized efficiency lies between 40.0 and 41.3. This

  12. Gas-Assisted Heating Technology for High Aspect Ratio Microstructure Injection Molding

    Directory of Open Access Journals (Sweden)

    Shia-Chung Chen

    2013-01-01

    Full Text Available A hot gas is used for heating the cavity surface of a mold. Different mold gap sizes were designed. The mold surface temperature was heated to above the glass transition temperature of the plastic material, and the mold then closed for melt filling. The cavity surface can be heated to 130°C to assist the melt filling of the microfeatures. Results show that hot gas heating can improve the filling process and achieve 91% of the high aspect ratio microgrooves (about 640.38 μm of the maximum of 700 μm. The mold gap size strongly affects the heating speed and heating uniformity. Without surface preheating, the center rib is the highest. When the heating target temperature is 90°C or 100°C, the three microribs have a good uniformity of height. However, when the target temperature exceeds 100°C, the left side rib is higher than the other ribs.

  13. Low energy, high power hydrogen neutral beam for plasma heating

    Energy Technology Data Exchange (ETDEWEB)

    Deichuli, P.; Davydenko, V.; Ivanov, A., E-mail: ivanov@inp.nsk.su; Mishagin, V.; Sorokin, A.; Stupishin, N. [Budker Institute of Nuclear Physics, Prospect Lavrentieva 11, 630090 Novosibirsk (Russian Federation); Korepanov, S.; Smirnov, A. [Tri Alpha Energy, Inc., Foothill Ranch, California 92610 (United States)

    2015-11-15

    A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase the efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.

  14. Low energy, high power hydrogen neutral beam for plasma heating

    Science.gov (United States)

    Deichuli, P.; Davydenko, V.; Ivanov, A.; Korepanov, S.; Mishagin, V.; Smirnov, A.; Sorokin, A.; Stupishin, N.

    2015-11-01

    A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase the efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.

  15. Abnormal high surface heat flow caused by the Emeishan mantle plume

    Science.gov (United States)

    Jiang, Qiang; Qiu, Nansheng; Zhu, Chuanqing

    2016-04-01

    It is commonly believed that increase of heat flow caused by a mantle plume is small and transient. Seafloor heat flow data near the Hawaiian hotspot and the Iceland are comparable to that for oceanic lithosphere elsewhere. Numerical modeling of the thermal effect of the Parana large igneous province shows that the added heat flow at the surface caused by the magmatic underplating is less than 5mW/m2. However, the thermal effect of Emeishan mantle plume (EMP) may cause the surface hear-flow abnormally high. The Middle-Late Emeishan mantle plume is located in the western Yangtze Craton. The Sichuan basin, to the northeast of the EMP, is a superimposed basin composed of Paleozoic marine carbonate rocks and Mesozoic-Cenozoic terrestrial clastic rocks. The vitrinite reflectance (Ro) data as a paleogeothermal indicator records an apparent change of thermal regime of the Sichuan basin. The Ro profiles from boreholes and outcrops which are close to the center of the basalt province exhibit a 'dog-leg' style at the unconformity between the Middle and Upper Permian, and they show significantly higher gradients in the lower subsection (pre-Middle Permian) than the Upper subsection (Upper Permian to Mesozoic). Thermal history inversion based on these Ro data shows that the lower subsection experienced a heat flow peak much higher than that of the upper subsection. The abnormal heat flow in the Sichuan basin is consistent with the EMP in temporal and spatial distribution. The high-temperature magmas from deep mantle brought heat to the base of the lithosphere, and then large amount of heat was conducted upwards, resulting in the abnormal high surface heat flow.

  16. Dilatometric investigations of phase transformations at heating and cooling of hardened, unalloyed, high-carbon steels

    Directory of Open Access Journals (Sweden)

    J. Pacyna

    2011-05-01

    Full Text Available Purpose: The reason for writing this paper was to describe the kinetics of phase transformations during continuous heating from hardened state and subsequent cooling of unalloyed high carbon steel.Design/methodology/approach: Dilatometric investigations were performed using a DT 1000 dilatometer of a French company Adamel. Samples after quenching and quenching and sub-quenching in liquid nitrogen (-196 °C were heated up 700 °C at the rate of 0.05 °C/s and subsequent cooled to room temperature at the rate of 0.05 °C/s.Findings: Regardless of heating the hardened high-carbon steel to 700 °C, a small fraction of the retained austenite remained in its structure, and was changing into fresh martensite only during cooling in the temperature range: 280°C-170°C.Research limitations/implications: Schematic presentation of the differential curve of tempering of the hardened high-carbon, unalloyed steel illustrating the phase transformations occurring during heating from hardened state.Practical implications: An observation, that a small fraction of the retained austenite remained in the structure of tempered high-carbon steel, indicates that even unalloyed steel should be tempered two times.Originality/value: Detailed descriptions of kinetics phase transformations during heating from hardened state of unalloyed high carbon steel.

  17. High-temperature industrial process heat: technology assessment and introduction rationale

    Energy Technology Data Exchange (ETDEWEB)

    1978-03-03

    Three specific topics of interest to DOE are addressed: to establish the significance and identify the role of high-temperature process heat in the nation's energy economy; to identify the role of solar thermal power in these high-temperature industrial applications in terms of possible markets and economic potential; and to recommend programmatic approaches for these solar thermal high-temperature process heat activities, including proposed content for initial Request for Proposals (RFPs) to accomplish such activities. The scope of the work required to accomplish these three purposes included the following: review of US industrial energy requirements, survey of current DOE low-temperature Agricultural and Industrial Process Heat Program, examination of high-temperature solar thermal electric systems already developed or under development by DOE and industry, and coordination with the high-energy user segments of industry (i.e., cement, chemical and petroleum) to find additional markets for some or all of the systems or components being developed in the DOE solar thermal electric program. Statistical data are presented identifying energy allocations to process heat and defining DOE's involvement. Three current fossil fuel process heat system examples are provided and the corresponding solar potential is identified.

  18. Arrange and average algorithm for the retrieval of aerosol parameters from multiwavelength high-spectral-resolution lidar/Raman lidar data.

    Science.gov (United States)

    Chemyakin, Eduard; Müller, Detlef; Burton, Sharon; Kolgotin, Alexei; Hostetler, Chris; Ferrare, Richard

    2014-11-01

    We present the results of a feasibility study in which a simple, automated, and unsupervised algorithm, which we call the arrange and average algorithm, is used to infer microphysical parameters (complex refractive index, effective radius, total number, surface area, and volume concentrations) of atmospheric aerosol particles. The algorithm uses backscatter coefficients at 355, 532, and 1064 nm and extinction coefficients at 355 and 532 nm as input information. Testing of the algorithm is based on synthetic optical data that are computed from prescribed monomodal particle size distributions and complex refractive indices that describe spherical, primarily fine mode pollution particles. We tested the performance of the algorithm for the "3 backscatter (β)+2 extinction (α)" configuration of a multiwavelength aerosol high-spectral-resolution lidar (HSRL) or Raman lidar. We investigated the degree to which the microphysical results retrieved by this algorithm depends on the number of input backscatter and extinction coefficients. For example, we tested "3β+1α," "2β+1α," and "3β" lidar configurations. This arrange and average algorithm can be used in two ways. First, it can be applied for quick data processing of experimental data acquired with lidar. Fast automated retrievals of microphysical particle properties are needed in view of the enormous amount of data that can be acquired by the NASA Langley Research Center's airborne "3β+2α" High-Spectral-Resolution Lidar (HSRL-2). It would prove useful for the growing number of ground-based multiwavelength lidar networks, and it would provide an option for analyzing the vast amount of optical data acquired with a future spaceborne multiwavelength lidar. The second potential application is to improve the microphysical particle characterization with our existing inversion algorithm that uses Tikhonov's inversion with regularization. This advanced algorithm has recently undergone development to allow automated and

  19. Effect of Heat Treatment on Mechanical Properties and Microstructure Morphology of Low-Alloy High-Strength Steel

    Directory of Open Access Journals (Sweden)

    Bolanowski K.

    2016-06-01

    Full Text Available The paper analyzes the influence of different heat treatment processes on the mechanical properties of low-alloy high-strength steel denoted by Polish Standard (PN as 10MnVNb6. One of the findings is that, after aging, the mechanical properties of rolled steel are high: the yield strength may reach > 600 MPa, and the ultimate tensile strength is > 700 MPa. These properties are largely dependent on the grain size and dispersion of the strengthening phase in the ferrite matrix. Aging applied after hot rolling contributes to a considerable rise in the yield strength and ultimate tensile strength. The process of normalization causes a decrease in the average grain size and coalescence (reduction of dispersion of the strengthening phase. When 10MnVNb6 steel was aged after normalization, there was not a complete recovery in its strength properties.

  20. Development and Demonstration of a High Efficiency, Rapid Heating, Low NOx Alternative to Conventional Heating of Round Steel Shapes, Steel Substrate (Strip) and Coil Box Transfer Bars

    Energy Technology Data Exchange (ETDEWEB)

    Kurek, Harry; Wagner, John

    2010-01-25

    Direct Flame Impingement involves the use of an array of very high-velocity flame jets impinging on a work piece to rapidly heat the work piece. The predominant mode of heat transfer is convection. Because of the locally high rate of heat transfer at the surface of the work piece, the refractory walls and exhaust gases of a DFI furnace are significantly cooler than in conventional radiant heating furnaces, resulting in high thermal efficiency and low NOx emissions. A DFI furnace is composed of a successive arrangement of heating modules through or by which the work piece is conveyed, and can be configured for square, round, flat, and curved metal shapes (e.g., billets, tubes, flat bars, and coiled bars) in single- or multi-stranded applications.

  1. Glucose concentration and blood acid-basis status in high-yielding dairy cows during heat stress

    Directory of Open Access Journals (Sweden)

    Vujanac Ivan

    2011-01-01

    Full Text Available The objective of this work was to examine the effect of heat stress on glucose and pH values in blood of high-yielding dairy cows in the early stage of lactation, as well as to determine whether the changes in these parameters are interdependent under such conditions. An experiment was performed on high-yielding dairy cows during the summer and the spring periods. Forty cows were selected, twenty each for the two periods under investigation. In the course of the experiment, the temperature humidity index (THI was determined for the entire period of investigations, and then also the average daily THI, nightmorning THI (average value of hourly THI measured from 22h on the previous day until 10h of the current day, as well as the day-night THI (average value of hourly THI measured during the period from 10h to 22h of the current day. The pH and glucose concentration were determined in blood samples taken in the morning and afternoon of days 30, 60, and 90 of lactation during the spring and summer periods of the investigations. Based on the results for the THI, it was established that the animals were not exposed to the effect of extreme heat stress during the spring period of investigations, while they were periodically exposed to moderate but also extreme heat stress during the summer, in particular in the afternoon hours. It can be concluded from the results obtained for the blood pH that the cows were in respiratory alkalosis during the summer in the morning and afternoon hours on day 30, in the afternoon hours of days 60 and 90 of lactation, as well as in the afternoon on day 90 of lactation during the spring period of investigations. During the summer period, there were no statistically significant differences between the pH value determined in the morning and afternoon hours on day 30 of lactation, while the pH value was significantly higher in the afternoon hours than in the morning hours on days 60 and 90 of lactation. There were no

  2. Solar heating and domestic hot water system installed at North Dallas High School

    Science.gov (United States)

    1980-01-01

    The solar energy system located at the North Dallas High School, Dallas, Texas is discussed. The system is designed as a retrofit in a three story with basement, concrete frame high school building. Extracts from the site files, specification references for solar modification to existing building heating and domestic hot water systems, drawings, installation, operation and maintenance instructions are included.

  3. Plasma wakefields driven by an incoherent combination of laser pulses: a path towards high-average power laser-plasma accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Benedetti, C.; Schroeder, C.B.; Esarey, E.; Leemans, W.P.

    2014-05-01

    he wakefield generated in a plasma by incoherently combining a large number of low energy laser pulses (i.e.,without constraining the pulse phases) is studied analytically and by means of fully-self-consistent particle-in-cell simulations. The structure of the wakefield has been characterized and its amplitude compared with the amplitude of the wake generated by a single (coherent) laser pulse. We show that, in spite of the incoherent nature of the wakefield within the volume occupied by the laser pulses, behind this region the structure of the wakefield can be regular with an amplitude comparable or equal to that obtained from a single pulse with the same energy. Wake generation requires that the incoherent structure in the laser energy density produced by the combined pulses exists on a time scale short compared to the plasma period. Incoherent combination of multiple laser pulses may enable a technologically simpler path to high-repetition rate, high-average power laser-plasma accelerators and associated applications.

  4. Aggregation and Averaging.

    Science.gov (United States)

    Siegel, Irving H.

    The arithmetic processes of aggregation and averaging are basic to quantitative investigations of employment, unemployment, and related concepts. In explaining these concepts, this report stresses need for accuracy and consistency in measurements, and describes tools for analyzing alternative measures. (BH)

  5. Concept for support and heating of plate-like samples in the ultra-high vacuum

    Science.gov (United States)

    Tröger, L.; Pieper, H. H.; Reichling, M.

    2013-01-01

    We present the concept for a sample holder designed for mounting and heating of plate-like samples that is based on a clamping mechanism for easy handling. The clamping mechanism consists of a U-shaped bracket encompassing the sample support plate from the rear. Two spring wires are fixed in the walls of the bracket spanning the sample to secure it with only two point contacts. This enables the sample to freely expand or contract during heating and cooling. To accommodate for a large variety in sample size, shape, and quality, we introduce two designs differing in the generation of the clamping force: One pressing the sample against the spring wires, the other one pulling the spring wires onto the sample. Both designs yield an automatically even alignment of the sample during the mounting process to achieve an even load distribution and reliable fixation specifically for brittle samples. For high temperature treatment, the sample holders are enhanced by a resistive heating plate. As only the sample and a small fraction of the sample holder are heated, temperatures of 1300 °C are reached with only 8 W heating power. The sample support and heating components are mounted on a 11 mm × 13 mm base plate with a handle that can be transferred between the sample entry stage, the preparation stage, and surface science experiments in the ultra-high vacuum system.

  6. Heat transport in the high-pressure ice mantle of large icy moons

    Science.gov (United States)

    Choblet, G.; Tobie, G.; Sotin, C.; Kalousová, K.; Grasset, O.

    2017-03-01

    While the existence of a buried ocean sandwiched between surface ice and high-pressure (HP) polymorphs of ice emerges as the most plausible structure for the hundreds-of-kilometers thick hydrospheres within large icy moons of the Solar System (Ganymede, Callisto, Titan), little is known about the thermal structure of the deep HP ice mantle and its dynamics, possibly involving melt production and extraction. This has major implications for the thermal history of these objects as well as on the habitability of their ocean as the HP ice mantle is presumed to limit chemical transport from the rock component to the ocean. Here, we describe 3D spherical simulations of subsolidus thermal convection tailored to the specific structure of the HP ice mantle of large icy moons. Melt production is monitored and melt transport is simplified by assuming instantaneous extraction to the ocean above. The two controlling parameters for these models are the rheology of ice VI and the heat flux from the rock core. Reasonable end-members are considered for both parameters as disagreement remains on the former (especially the pressure effect on viscosity) and as the latter is expected to vary significantly during the moon's history. We show that the heat power produced by radioactive decay within the rock core is mainly transported through the HP ice mantle by melt extraction to the ocean, with most of the melt produced directly above the rock/water interface. While the average temperature in the bulk of the HP ice mantle is always relatively cool when compared to the value at the interface with the rock core (∼ 5 K above the value at the surface of the HP ice mantle), maximum temperatures at all depths are close to the melting point, often leading to the interconnection of a melt path via hot convective plume conduits throughout the HP ice mantle. Overall, we predict long periods of time during these moons' history where water generated in contact with the rock core is transported to

  7. 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...

  8. Evaluation the microwave heating of spinel crystals in high-level waste glass

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J. H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Washington, A. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL)

    2015-08-18

    In this report, the microwave heating of a crystal-free and a partially (24 wt%) trevorite-crystallized waste glass simulant were evaluated. The results show that a 500 mg piece of partially crystallized waste glass can be heated from room-temperature to above 1600 °C (as measured by infrared radiometry) within 2 minutes using a single mode, highly focused, 2.45 GHz microwave, operating at 300 W. X-ray diffraction measurements show that the partially crystallized glass experiences an 87 % reduction in trevorite following irradiation and thermal quenching. When a crystal-free analogue of the same waste glass simulant composition is exposed to the same microwave radiation it could not be heated above 450 °C regardless of the heating time.

  9. Natural Heat-Sinking Control Method for High-Speed Actuation of the SMA

    Directory of Open Access Journals (Sweden)

    Tamio Arai

    2008-11-01

    Full Text Available This paper describes two methodologies for increasing the actuation speed of the shape memory alloy (SMA actuator in ambient environment. The first method involves the implementation of a simple, light-weight heat sink, which consists only of a combination of an outer metal tube with the silicone grease, but able to cool the heated alloy effectively. The second method describes a high current pulse actuation that actuates the alloy fastly using pulses in the milliseconds order. We hypothesize that a fast actuation of the SMA results in small increase in temperature, due to energy transformation from heat energy to the kinetic energy in the SMA. This new heating method revolutionizes the actuation of the alloy for a significantly faster response.

  10. Multiwalled carbon nanotube/polydimethylsiloxane composite films as high performance flexible electric heating elements

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Jing; Jeong, Young Gyu, E-mail: ygjeong@cnu.ac.kr [Department of Advanced Organic Materials and Textile System Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

    2014-08-04

    High performance elastomeric electric heating elements were prepared by incorporating various contents of pristine multiwalled carbon nanotube (MWCNT) in polydimethylsiloxane (PDMS) matrix by using an efficient solution-casting and curing technique. The pristine MWCNTs were identified to be uniformly dispersed in the PDMS matrix and the electrical percolation of MWCNTs was evaluated to be at ∼0.27 wt. %, where the electrical resistivity of the MWCNT/PDMS composite films dropped remarkably. Accordingly, the composite films with higher MWCNT contents above 0.3 wt. % exhibit excellent electric heating performance in terms of temperature response rapidity and electric energy efficiency at constant applied voltages. In addition, the composite films, which were thermally stable up to 250 °C, showed excellent heating-cooling cyclic performance, which was associated with operational stability in actual electric heating applications.

  11. Relationship between the exposure dose of high intensity focused ultrasound and the heated necrosis element

    Institute of Scientific and Technical Information of China (English)

    FENG Ruo; ZHANG Qiang; LI Faqi; ZHENG Xiaozheng; BAI Jin; XU Jianyi; WANG Yaojun; WANG Zhibiao

    2004-01-01

    Heated necrosis element of tissues is the basis for treating tumor by high intensity focused ultrasound (HIFU), so study on the relationship between the HIFU exposure dose and the heated necrosis element of tissues is of great significance for both HIFU clinical applications and basic research. Using Pennes and Rayleigh formulae the relationship between the exposure dose of an annular focused transducer and the heated necrosis element (I.e. Biological focused region) in a bovine liver in vitro at a depth of 2 cm is simulated in an exposure dose range with radiation sound intensity of 7000~25400 W/cm2 and exposure time of 0~20 s. The theoretical results appear to be in quite good agreement with the experimental ones. It is shown that on the basis of existing theories the heated necrosis element produced by HIFU exposure can be predicted. The deviation of the theory from the experiments under higher exposure dose has also been discussed.

  12. Melting of troilite at high pressure in a diamond cell by laser heating

    Science.gov (United States)

    Bassett, William A.; Weathers, Maura S.

    1987-01-01

    A system for measuring melting temperatures at high pressures is described. The sample is heated with radiation from a YAG laser. The beam is reflected downward through a microscope objective, through the upper diamond anvil, and focused onto the sample. Hense, intense heating is produced only at the sample and not within the diamond anvils. A vidicon system is used to observe the sample during heating. Incandescent light from the heated sample passes back through the objective lens into a grating spectrometer. The spectrum of the incandescent light is received by the photodiode array and stored in the multichannel analyzer. These data can then be transferred to floppy disk for analysis. A curve fitting program is used to compare the spectra with standard blackbody curves and to determine the temperature. Pressure is measured by the ruby fluorescence method. The system was used to study the melting behavior of natural troilite (FeS).

  13. On Averaging Rotations

    DEFF Research Database (Denmark)

    Gramkow, Claus

    1999-01-01

    In this article two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very offten the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belong...... approximations to the Riemannian metric, and that the subsequent corrections are inherient in the least squares estimation. Keywords: averaging rotations, Riemannian metric, matrix, quaternion...

  14. Reassembling and testing of a high-precision heat capacity drop calorimeter. Heat capacity of some polyphenyls at T = 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Luis M.N.B.F., E-mail: lbsantos@fc.up.pt [Centro de Investigacao em Quimica, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Rocha, Marisa A.A.; Rodrigues, Ana S.M.C. [Centro de Investigacao em Quimica, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Stejfa, Vojtech; Fulem, Michal [Department of Physical Chemistry, Institute of Chemical Technology, Technicka 5, CZ-166 28 Prague 6 (Czech Republic); Bastos, Margarida [Centro de Investigacao em Quimica, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal)

    2011-12-15

    Graphical abstract: Highlights: > We present the reassembling, improvement and testing of a high-precision C{sub p} drop calorimeter. > The apparatus was tested, using benzoic acid and hexafluorobenzene. > The high sensitivity of the apparatus is comparable to the one obtained in adiabatic calorimetry. > Heat capacities at T = 298.15 K of some polyphenyls were measured. > Subtle heat capacity differences among position isomers (ortho, meta, para) were detected. - Abstract: The description of the reassembling and testing of a twin heat conduction, high-precision, drop microcalorimeter for the measurement of heat capacities of small samples are presented. The apparatus, originally developed and used at the Thermochemistry Laboratory, Lund, Sweden, has now been reassembled and modernized, with changes being made as regarding temperature sensors, electronics and data acquisition system. The apparatus was thereafter thoroughly tested, using benzoic acid and hexafluorobenzene as test substances. The accuracy of the C{sub p,m}{sup 0} (298.15 K) data obtained with this apparatus is comparable to that achieved by high-precision adiabatic calorimetry. Here we also present the results of heat capacity measurements on of some polyphenyls (1,2,3-triphenylbenzene, 1,3,5-triphenylbenzene, p-terphenyl, m-terphenyl, o-terphenyl, p-quaterphenyl) at T = 298.15 K, measured with the renewed high precision heat capacity drop calorimeter system. The high resolution and accuracy of the obtained heat capacity data enabled differentiation among the ortho-, meta-, and para-phenyl isomers.

  15. High-frequency radar observations of PMSE modulation by radio heating

    Science.gov (United States)

    Senior, Andrew; Rietveld, Michael; Mahmoudian, Alireza; La Hoz, Cesar; Kosch, Michael; Scales, Wayne; Pinedo, Henry

    The first observations using high-frequency (8 MHz) radar of modulation of polar mesospheric summer echoes (PMSE) by radio heating of the ionosphere are presented. The experiment was performed at the EISCAT facility near Tromsø, Norway. The observations are compared with simultaneous radar measurements at 224 MHz and with a model of the dusty plasma response to electron heating. Agreement between the model and observations is good considering technical limitations on the 8 MHz radar measurements. Predictions made about the response of high-frequency PMSE to heating where dust charging dominates over diffusion, opposite to the situation at very high-frequencies are confirmed. Suggestions are made about improving the 8 MHz observations to overcome the current limitations.

  16. Coupled thermochemical, isotopic evolution and heat transfer simulations in highly irradiated UO2 nuclear fuel

    Science.gov (United States)

    Piro, M. H. A.; Banfield, J.; Clarno, K. T.; Simunovic, S.; Besmann, T. M.; Lewis, B. J.; Thompson, W. T.

    2013-10-01

    Predictive capabilities for simulating irradiated nuclear fuel behavior are enhanced in the current work by coupling thermochemistry, isotopic evolution and heat transfer. Thermodynamic models that are incorporated into this framework not only predict the departure from stoichiometry of UO2, but also consider dissolved fission and activation products in the fluorite oxide phase, noble metal inclusions, secondary oxides including uranates, zirconates, molybdates and the gas phase. Thermochemical computations utilize the spatial and temporal evolution of the fission and activation product inventory in the pellet, which is typically neglected in nuclear fuel performance simulations. Isotopic computations encompass the depletion, decay and transmutation of more than 2000 isotopes that are calculated at every point in space and time. These computations take into consideration neutron flux depression and the increased production of fissile plutonium near the fuel pellet periphery (i.e., the so-called “rim effect”). Thermochemical and isotopic predictions are in very good agreement with reported experimental measurements of highly irradiated UO2 fuel with an average burnup of 102 GW d t(U)-1. Simulation results demonstrate that predictions are considerably enhanced when coupling thermochemical and isotopic computations in comparison to empirical correlations. Notice: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.

  17. Reynolds-averaged Navier-Stokes investigation of high-lift low-pressure turbine blade aerodynamics at low Reynolds number

    Science.gov (United States)

    Arko, Bryan M.

    Design trends for the low-pressure turbine (LPT) section of modern gas turbine engines include increasing the loading per airfoil, which promises a decreased airfoil count resulting in reduced manufacturing and operating costs. Accurate Reynolds-Averaged Navier-Stokes predictions of separated boundary layers and transition to turbulence are needed, as the lack of an economical and reliable computational model has contributed to this high-lift concept not reaching its full potential. Presented here for what is believed to be the first time applied to low-Re computations of high-lift linear cascade simulations is the Abe-Kondoh-Nagano (AKN) linear low-Re two-equation turbulence model which utilizes the Kolmogorov velocity scale for improved predictions of separated boundary layers. A second turbulence model investigated is the Kato-Launder modified version of the AKN, denoted MPAKN, which damps turbulent production in highly strained regions of flow. Fully Laminar solutions have also been calculated in an effort to elucidate the transitional quality of the turbulence model solutions. Time accurate simulations of three modern high-lift blades at a Reynolds number of 25,000 are compared to experimental data and higher-order computations in order to judge the accuracy of the results, where it is shown that the RANS simulations with highly refined grids can produce both quantitatively and qualitatively similar separation behavior as found in experiments. In particular, the MPAKN model is shown to predict the correct boundary layer behavior for all three blades, and evidence of transition is found through inspection of the components of the Reynolds Stress Tensor, spectral analysis, and the turbulence production parameter. Unfortunately, definitively stating that transition is occurring becomes an uncertain task, as similar evidence of the transition process is found in the Laminar predictions. This reveals that boundary layer reattachment may be a result of laminar

  18. High-definition color image in dye thermal transfer printing by laser heating

    Science.gov (United States)

    Kitamura, Takashi

    1999-12-01

    In laser thermal transfer printing using dye sublimation type medium, a high definition and continuous tone image can be obtained easily because the laser beam is focused to small spot and heat energy can be controlled by the pulse width modulation of laser light. The donor ink sheet is composed of the laser absorbing layer and sublimation dye layer. The tone reproduction was depend on the mixture ratio of dye to binder and thickness of ink layer. The four color ink sheets such as cyan, magenta, yellow and black were prepared for color printing image which have a high resolution and good continuous tone reproduction using sublimation dye transfer printing by laser heating.

  19. Surprisingly high stability of barley lipid transfer protein, LTP1, towards denaturant, heat and proteases

    DEFF Research Database (Denmark)

    Lindorff-Larsen, Kresten; Winther, J R

    2001-01-01

    Barley LTP1 belongs to a large family of plant proteins termed non-specific lipid transfer proteins. The in vivo function of these proteins is unknown, but it has been suggested that they are involved in responses towards stresses such as pathogens, drought, heat, cold and salt. Also, the proteins...... have been suggested as transporters of monomers for cutin synthesis. We have analysed the stability of LTP1 towards denaturant, heat and proteases and found it to be a highly stable protein, which apparently does not denature at temperatures up to 100 degrees C. This high stability may be important...

  20. Development Of An Industrial High Temperature Heat Pump With Twin Screw Compressor

    OpenAIRE

    He, Yongning; Yang, Dongfang; Cao, Feng; Li, Gang

    2014-01-01

    In industrial applications, 90-150? hot water needed during production processes is traditionally provided by fuel-fired boilers. The usage of fuel-fired boiler has a low efficiency of energy use and potential danger of explosion. 30-60?waste water with large amount of energy is rejected to environment directly, which causes a great energy loss and thermal pollution. Seeking for a much high efficiency and safe heating pattern is essential to replace the boilers used now. High temperature heat...